Abstract

Background

Injuries in athletes are becoming more of a daunting factor for the coaches, parents and athlete. Researchers are currently investigating what the most effective preventative strategy is to try and reduce the number of hamstring strain injuries.

Objective

This study was done to compare, analyse and discuss the effects that a 6-week Nordic hamstring curl treatment plan had on eccentric hamstring strength and flexibility in netballers.

Participants

14 female amateur University netball players (age SD = 19.7 ± 1.12, height SD = 1.65 ± 0.04 and weight SD 67.9 ± 6.5).

Method

Participants were randomly selected to be in the treatment or control group. An Isokinetic dynamometer was used to measure eccentric hamstring strength in all participants pre- and post-treatment plan. A manual goniometer was used to measure their hamstring flexibility pre- and post-intervention. The treatment group undertook a 6-week treatment plan consisting of Nordic hamstring curls with the dose and frequency changing every week.

Results

There was a significant difference in eccentric hamstring strength and flexibility in the treatment group once the 6-week treatment plan had been completed.

Conclusion

Results from the study agree with previous literature that Nordic hamstring curls are an effective strategy to strengthen the hamstrings and so reduce the number of hamstring strain injuries.

Key words: Nordic Hamstring curls, eccentric hamstring strength, flexibility, netball

Contents

		Page
Abstract		ii
Acknowledgements		iii
Contents		iv
List of Figures		v
List of Tables		vi
1. Introduction		1
2. Review of Literature		12
2.1	Gender differences	12
2.2	Common injuries in sport	14
2.3	Common injuries in netball	15
2.4	Preventative strategy	18
3. Methods		21
4. Results		26
5. Discussion		30
5.1	Limitations	33
5.2	Future Research	34
6. Conclusion		36
6.1	Practical Implications	36
References		37
Appendices		51
	Appendix A	52
	Appendix B	53
	Appendix C	54
	Appendix D	56
	Appendix E	58
	Appendix F	60
	Appendix G	62

List of Figures

		Page
Figure 1 – Dynamic valgus collapse		18
Figure 2 – SLR		25
Figure 3 – NHC		26
Figure 4 – 4 corners		26
Figure 5 – Graph showing average strength for both 60o and 180o/sec pre- and post-treatment plan		29
Figure 6 – Graph showing average flexibility in the TG both pre- and post-treatment plan		31

List of Tables

		Page
Table 1 – NHC training regime		25
Table 2 – Descriptive statistics showing strength averages and standard deviations pre-treatment plan		26
Table 3 – Descriptive statistics showing strength averages and standard deviations post-treatment plan		26
Table 4 – Results from paired T-test for strength data pre- and post-treatment plan		27
Table 5 – Descriptive statistics showing the averages and standard deviations of the flexibility readings pre-treatment plan		28
Table 6 – Descriptive statistics showing the averages and standard deviations of the flexibility readings post-treatment plan		28
Table 7 – Results from paired T-test for flexibility data pre- and post-treatment plan		28

1. Introduction

Over the past 20 years, there has been a steady increase in the number of people participating in sport, whether it be competitively or recreationally, who do not think about the possible negative consequences associated with injury, and the implications it could have on their day to day lives. A sports injury can be defined as one that has occurred while participating in sport and which has led to either: a reduction in the amount or level of sports activity; need for medical advice or treatment; and/or adverse economic or social effects for the person (Stevenson et al., 2000). Rhodes (2016) showed that 15.8 million people play sport or take part in exercise at least once a week, and that participation has risen by 1.7 billion since 2005. This growth has proven to be very valuable for those females that wish to develop, practice and demonstrate athletic abilities. England Netball (2016) released their latest Active People Survey (APS) in 2016 and proved to be positive for netball, as the number of people playing has increased by 16.4% in the last year. The APS is a survey used to measure the number of adults that take part in sports across England.

Netball is a team sport that has one of the largest participation rates within the Commonwealth, in particular the United Kingdom, Australia and New Zealand (Chandler et al. 2014), with more than 20 million athletes participating in the sport (Delextrat and Goss-Sampson, 2010).  Netball is a fast, skilful game requiring a high level of anaerobic and aerobic fitness (McManus, Stevenson and Finch, 2006). It is also physically demanding as it requires a high degree of speed, strength, fitness and flexibility. However, because of the physical demands there is a high risk of injury to the athlete. A netball team consists of 7 players on the court at one time, and each position has different court roles and restrictions which affects the physical demands on each individual player (appendix A). Fox, et al. (2013) found that the centre (C) was more active than any other position, which causes them to have greater physical demands. The goal keeper (GK) and goal shooter (GS) positions were least active. These findings agree with a study by Davidson and Trewartha (2008) which also showed that the ‘C’ has the greatest physical demands.

In comparison, GK’s and GS’s tend to demonstrate few repetitions of movement activities, and demonstrated the least time walking, jogging or running, and the greatest amount of time standing. In contrast, C’s spent the least time walking and standing, and the greatest amount of time jogging or sprinting (Davidson and Trewartha, 2008). In terms of the mean percentage of time spent active (± s), the positional rankings from highest to lowest were C (82.7 ± 4.1), Wing attack (WA) (76.2 ± 7.6), Goal Defence (GD) (75.9 ± 10.2), Goal Attack (GA) (75.3 ± 5.8), Wing Defence (WD) (71.6 ± 8.2), GK (53.7 ± 9.0) and GS (53.5 ± 14.3) (Fox, et al. 2013). Research by Steele (1990) monitored heart rate (HR) to investigate the physiological responses to netball training and match play. Almost 50% of match time was found to be at intensities between 75 and 85% of maximal HR, whereas the majority of training time was spent at a HR below 75% of maximal HR. McManus, Stevenson and Finch (2006) have stated that 81% of these netballers compete at a club or association level at least once a week and are aged between 18 and 34. Fox et al. (2013) have stated that the most frequently performed activity by all positions is shuffling and walking.

Jogging, running and sprinting are the most frequently performed by the players involved in mid-court play (GD, WD, C, WA and GA). Offensive based activities (i.e. catching and passing) were more frequently performed by the attacking court positions (C, WA, GA and GS); whereas defensive based activities (i.e. guarding and off-ball guarding) are more frequently performed by the defensive players (GK, GD, WD and C). The frequency of jumping was relatively consistent across all positions, apart from the GS performing far fewer jumps than all other positions. The GK and GS performed more shooting circle based activities (goal, rebound and defend) than the GD and GA (Fox et al., 2013).

Gamble (2011) has stated that netball being a sport that is exclusively played by females at elite level, netball carries a level of intrinsic injury risk equal to that of other female team sports. However, in the case of netball, there are additional extrinsic risk factors because of the rules and nature of the sport. A defining factor is the rule that players must come to a stop within one and a half steps of receiving the ball, decelerating and stopping (Otago, 2004). The various landing strategies in the act of catching the ball represents a key movement skill set for the netball player.

This is done to avoid rule infringements and to be more effective and efficient on court, but most importantly, it is done to guard against lower limb injuries. Otago (2004) has also researched that the ‘pivot and turn’ movement when receiving the ball appears to impose the greatest lower limb loading, and so the greatest chance of suffering from an injury. A systematic review by Goldman and Jones (2011) gave evidence that the hamstring muscles are most vulnerable to injury in the late phase of running, where there is a rapid change from eccentric to concentric function, when the leg is decelerating to strike the ground. Walden et al., (2017) have stated that netball injuries can be a mix of both upper and lower limb injuries, as well as impact, acute injuries and gradual, overuse injuries. Injuries to the shoulders (rotator cuff) are the most common in the upper limbs. This is due to the repeated throwing done whilst playing netball. Finger and hand injuries may occur because of impacts from the ball or an opponent grasping for the ball at the same time. Injuries suffered in the lower limbs mostly occur when pivoting and because of the quick changes in direction, as well as repeated jumping. The most common injuries in the lower limbs are: ankle sprains, Achilles tendonitis, jumpers knee, patellofemoral pain, hamstring strains and shin splints.

Hamstring muscle strains and injuries are common among high school, college, and professional athletes, especially in sports with sprinting demands, kicking and sudden accelerations (Sebelien et al. 2014). Hamstring injuries are typically characterised by the acute onset of posterior thigh pain, and are usually accompanied by a partial-to-complete disruption of muscle fibres in the hamstring muscle group (Bourne, 2016).Mendiguchia, Alentorn-Gell and Brughelli (2012) stated that hamstring strains can be predicted by strength and flexibility. Miller (2015, p1) has defined an eccentric muscle action as ‘the overall lengthening of the muscle whilst it develops tension and contracts to control the motion performed by an outside force.’ Flexibility has been defined as ‘the ability of a muscle to lengthen and allow one joint (or more than one joint in a series) to move through a range of motion’ (Zachezewski, 1989, p. 698).

Injury prevention has become a major issue, because of the lack of data collected on sports injuries, particularly at a non-elite level and is a concern both nationally and internationally. There are several strategies which have been researched to try and prevent and/or reduce the number of hamstring strain injuries suffered by athletes. Some of the exercises used to try and prevent said injuries are those such as: Nordic hamstring curls, stiff-leg/Romanian deadlift, bilateral drop landing, bilateral depth jumps, hang power clean/hang power stretch, squat clean/squat snatch (emphasising a deep catch) and single leg, multiplanar variations of these exercises. These are found in Turner et al. (2014). 

However, one of the most common preventative strategies to reduce the number of hamstring strain injuries is the use of Nordic Hamstring Curls (NHCs). NHCs are used to improve eccentric hamstring strength, and hence reduce the chance of injury (Opar et al., 2015). Schmitt, Tim and McHugh (2012) have stated that most hamstring strains occur because of insufficient eccentric hamstring strength. A number of studies (Woods et al., 2004; Clanton and Coupe, 1998; and Kujala, Orava and Jarvinen, 1997) have suggested that hamstring strain injuries occur during the latter part of the swing phase of running when the hamstrings are working to decelerate knee extension. This means that the muscle is developing tension while lengthening. The hamstrings must change from functioning eccentrically to decelerate knee extension in the late swing, to concentrically where it becomes an active extensor of the hip joint (Woods et al., 2004; Clanton and Coupe, 1998; Drezner, 2003).

A study by Verrall et al. (2001) suggested that the muscle is most vulnerable to injury during the rapid change from eccentric to concentric strength. There are several proposed benefits of enhanced flexibility and they are: reduced risk of injury (Bandy, Irion and Briggler, 1997; Halbertsma, van Bolhuis and Goeken, 1999; and Hurtig and Henderson, 1999) pain relief (Henricson and Fredriksson, 1984), and improved athletic performance (Anderson and Burke, 1991; and Worrell, Smith and Winegardner, 1994).

The aim of the study is to compare, analyse and discuss the effects that a 6-week Nordic hamstring curl training programme has on eccentric hamstring strength and flexibility in amateur netball players. The aim is underpinned by the research question:

‘Do Nordic Hamstring Curls have an effect on eccentric hamstring strength and flexibility in amateur netball players?’

The null hypothesis is that there will be no significant difference in eccentric hamstring strength and flexibility in the treatment group.

The alternative hypothesis is that there will be a significant difference in eccentric hamstring strength and flexibility in the netballers carrying out the NHCs when comparing them to the control group, which are not carrying out any kind of treatment plan or preventative strategy.

2. Review of Literature

2.1 Gender differences

When looking at the risk of injury between females and their male counterparts, females have been statistically proven to be more prone to injuries (Arendt and Dick, 1995). There are several reasons as to why females are more likely to suffer from some injuries than their male counterparts. Martineau (2004) proposed that hormonal factors and fluctuating levels of oestrogen before ovulation can affect the laxity of ligaments/joints and hence affect injury rates. Joint laxity has been described as looseness or increased mobility of the joints (Wolf, Cameron and Owens, 2011).

Female and male joint-laxity patterns diverge during and after puberty, whilst boys generally demonstrated a decrease in joint flexibility and ligament laxity with chronological age and maturation, girls demonstrate an increase (Quatmann, Quatmann and Hewett. 2007. Excessive knee laxity results in decreased dynamic knee stability during athletic manoeuvres and can be related to anterior cruciate ligament (ACL) injury risk (Hewett, Zazulak and Myer, 2006). The use of oral contraceptives (OC) has also been shown to affect the laxity of ligaments and therefore affect injury rates.

Progestins are the active components in OCs. Their supplementation disrupts the normal menstrual cycle and prevents ovulation to occur as it suppresses follicular development and rupture (Gray, Gugala and Baillargeon, 2015). Oestrogen levels drop due to halting the follicular development, and so, decreased oestrogen levels can equate to stronger ligaments and soft tissues. It has been stated that the use of OCs can decrease the number of traumatic ACL injuries (Moller-Nielsen and Hammar, 1991). A review by Smith, et al. (2012) found that the female sex hormone concentrations change over the course of the menstrual cycle, and the pattern of change may not be consistent from cycle to cycle. Female sex hormones influence the metabolism, biomechanical properties of the ACL and the composition.

Studies by Beynnon et al (2006) and Ruedl et al. (2009) found that there is a greater chance of injury of the ACL when in the preovulatory phase, as opposed to studies by Slauterback et al. (2002) and Myklebust et al. (2003) who stated that ACL injury is a bigger risk when in the follicular phase or the menstrual phase. However, more research is needed to develop in order to characterise the menstrual cycle phase status at the time of the injury, and see whether or not there are links between cycle phase and risk of suffering from ACL injury. A systematic review by Hewett, Zazulak and Myer (2007) found that more ACL injuries in women occurred during the follicular and ovulatory phases of the menstrual cycle, when the oestrogen levels are high.

Progestins are the active compounds in OC’s, and their supplementation disrupts the normal menstrual cycle and prevents ovulation by suppressing follicular development and rupture. Decreased serum oestrogen levels equate to stronger ligaments and soft tissues, including the ACL. It has been suggested that OC use among athletes decreases the number of traumatic injuries and prevents a premenstrual fall in physical fitness (Gray, Gugala and Baillargeon, 2016). The 6-week treatment plan covers the whole menstrual cycle, and so covers all phases.

Lower-extremity morphology or the alignment of the bone structure has also been shown to affect the rate of injury in females (Murphy, Connolly and Beynnon, 2003), however, not a lot of research has been done and the findings are not in agreement. There is a general consensus that the incidence of injuries is greater in competition than training sessions. It has been proved that the width of the bony crevice at the distal end of the thigh bone (femoral intercondylar notch) can affect ligament stability and injury rate (Kakarlapudi and Bickerstaff, 2001), the Q angle of the knee can also affect injury rates and ligament stability.

The Q angle is a measurement of the angle between the quadriceps muscles and the patella tendon, it provides information about the alignment of the knee joint (Walden et al., 2017). Souryal and Freeman (1993, p. 535) defined the notch width index as ‘the ratio of the width of the intercondylar notch to the width of the distal femur at the level of the popliteal groove.’ Two prospective studies (LaPrade and Burnett, 1994; Souryal and Freeman, 1993) in large groups of athletes have shown that athletes with smaller notch widths are at higher risk of suffering from an ACL injury. For practitioners, this is not always convenient as the notch width is non-modifiable.

Certain anatomical differences exist between genders; however more relevant – on the basis that they are modifiable – are the neuromuscular factors. Deficits in neuromuscular control of the lower limb kinetic chain are implicated in the injury mechanism for ACL rupture, which appears to be the case for female athletes particularly. Females often exhibit ligament dominance i.e. rely on passive joint stability rather than active muscular joint stabilisation (Ford, Myer and Hewett, 2003). Furthermore, there is a tendency for female athletes to demonstrate quadriceps dominance; which is potentially detrimental as the action of the quadriceps can increase anterior shear forces at the knee joint. This puts pressure on the knees and hamstrings, resulting in a greater chance of injury. The ACL is also particularly prone to injury when landing and change of direction movements are executed in an upright stance, which is again a characteristic of female athletes.

The change of direction and landing mechanics from jumping are essential in netball, so netballers are particularly prone to injury. Female athletes also demonstrate different motor patterns during landing and change of direction movements, such as reduced hamstring activity and asymmetric gastrocnemius activation, in comparison to male athletes.

There is a tendency for females to demonstrate quadriceps dominance; which is potentially detrimental as the action of the quadriceps can increase anterior shear forces at the knee joint (Silvers and Mandelbaum, 2007)

2.2 Common injuries in sport

Hoffmann (2017) has shown that the most common sporting injuries are: ankle sprains, groin pulls, hamstring strains, medial tibial stress syndrome (MTSS or shin splints), knee injury – ACL tear, patellofemoral syndrome; injury resulting from the repetitive movement of the kneecap against the thigh bone and tennis elbow (epicondylitis).

A systematic review and meta-analysis by Doherty et al. (2013) stated that there was a higher incidence of ankle sprains in females when comparing them to their male counterparts. Females suffered from 13.6 ankle sprains per 1000 hours of exposure, and males suffered 6.94/1000 (Doherty et al., 2013). Groin injuries have been shown to be responsible for 6% of all athletic injuries, with the prelevance in sports such as football as high as 12-16% (Alomar, 2015). Medial tibial stress syndrome (MTSS) or shin splints, account for 6 – 16% of all running injuries and have been responsible for as much as 50% of all lower leg injuries reported in athletic populations (Craig, 2008). Female team players suffer a considerably higher rate of ACL injury – reportedly 2-10 times higher than male athletes in the same sports (Silvers and Mandelbaum, 2007), this is particularly the case in sports which involve pivoting movements and jumping.

Muscle injuries of the lower limbs are common in most team sports. Hamstring strains are very common in sports characterized by maximal sprinting, kicking and sudden accelerations (Arnason et al. 2008 and Sconce et al. 2015). Sconce et al. (2015) have stated that hamstring injuries were the second most common injury while in training, however, they were the most frequent. The two main non-contact mechanisms which are responsible for hamstring strains are: high-speed running and deceleration, as in football and track and field events, and the other is during stretching movements carried out to extreme range of motion, both resulting in high-velocity eccentric loading.

Hamstring strain injury has been defined as ‘the increase of muscle length from the muscle resting length divided by the muscle resting length,’ (Liu et al. 2012). Sebelien et al. (2014) have stated that most hamstring strains are thought to occur during eccentric activity of the muscles. These injuries are also most likely to occur during two points of running: the take-off segment of the support phase and the late forward swing phase. When in the late swing-phase, the hamstrings are at the greatest length, contracting eccentrically to decelerate flexion of the thigh at the hip and extension of the lower leg at the knee. During sprinting, the deceleration phase shortens, requiring the hamstrings to work even harder to compensate for the forward momentum.

2.3 Common injuries in netball

The most common injury site in netballers is the lower leg (including the ankle and the knee) (Murphy, Connolly and Beynnon, 2003). Ankle injuries account for 31%-42% of injuries sustained in netball (Hutson and Speed, 2011). Injury to the knee is the second most common injury in netball, and is the most serious in terms of cost and disability (McManus, Stevenson and Finch, 2006), can also limit the capacity of individuals to return to their pre-injury level of sport participation (Ardern et al. 2011), and can also lead to the early development of osteoarthritis (Keays, 2010). It has been estimated that the incidence rate of knee injuries in netball is 2.82/1000 players (including a rate for severe injuries of 1.2/1000 players) (McManus, Stevenson & Finch, 2006). The most daunting injury which female athletes can suffer from is an anterior cruciate ligament (ACL) tear, as it can take six to eight months to recover from before the athlete returns to sport.

Most ACL injuries occur because of non-contact or indirect contact. This has been shown in a study by Arendt and Dick (1995) where they stated that the primary mechanism of ACL injuries is non-contact. Hewett et al., (1999) reported that 78% of all ACL injuries were noncontact in nature, and the most common injuries occurred when landing from a jump, while cutting, or with sudden deceleration. Stuelcken et al. (2016) reported that 81% of injuries occurred when the player was landing from a jump using predominantly either a split (symmetrical two-foot) or leap (single-leg) landing technique, given that players land in either of these two ways. It would seem logical that there must be something atypical about the landings in which injuries occur.

A study by Quatman and Hewett (2009) have stated that there is strong evidence that non-contact ACL injuries are likely to occur because of excess motion in the sagittal, frontal and/or transverse planes of motion. Many of the female athletes that suffered from ACL injuries were prone to having their legs fall into a ‘dynamic valgus collapse’ (DVC). This is when the femur (thigh bone) falls and rotates in towards the opposite leg – adduction and internal rotation, and the tibia and fibula rotate out – external rotation. During basketball events, Krosshaug et al., (2007) found that females were more than five times more prone to DVC than males, this is because of the anatomical position of the hips in females. As women have wider hips than males, their femurs are likely to collapse inwards. This valgus collapse, has been seen during cutting manoeuvres, deceleration manoeuvres, initial contact from jumping, semi-squat positions and push-off type movements in lateral manoeuvres.

Lack of active neuromuscular control, as evidenced by increased knee abduction motion and torque, and passive stability of the joint, as evidenced by increased joint laxity, may destabilise the knee and are predictive of increased ACL injury risk in female athletes (Myer et al., 2009). ACL injury likely occurs under conditions of high dynamic loading of the knee joint, when active muscular restraints do not adequately compensate for and adequately dampen joint loads (Myer et al., 2009). Decreased neuromuscular control of the joint may place stress on the passive ligament structures that exceed the failure strength of the ligament (Hewett et al., 2005).

Neuromuscular control of high-load movements is required to maintain dynamic knee stability during landing and pivoting. Hamstrings and quadriceps co-contraction may provide dynamic joint stabilisation and potentially protect the knee during sports-related tasks. Ford et al., (2011) reported that female athletes use increased quadriceps activation without matched increases in hamstrings activation when they performed drop landings with incrementally increased drop height intensity. Decreased hamstrings relative to quadriceps strength and recruitment is implicated as a potential mechanism for increased lower extremity injuries. Deficits in relative hamstring strength and recruitment may also contribute to increased ACL injury risk in female athletes (Myer et al. 2009). Hamstrings and increased hamstring strength is necessary because they produce high forces during both the stance phase and the late swing phases of running (Morin et al., 2015).

Various authors have suggested that the rate of force production in the hamstrings during the early stance phase was a limiting factor for maximal sprinting speed (Weyand et al., 2010; and Clark and Weyand, 2014), while another has suggested that the ability of the knee flexors to reduce the kinetic energy of the lower limb while lengthening during the late swing phase, and thus increasing the stride frequency was essential (Dorn, Schache and Pandy., 2012).

Figure 1: Dynamic Valgus Collapse

2.4 Preventative strategy

One of the most common strategies to implement into a training programme to try and reduce the chance of injury is the use of Nordic Hamstring Curls (NHCs). Opar et al., (2015) have stated that the NHC is the best supported exercise in the literature for the prevention of hamstring strain injury. The inclusion of hamstring exercises such as NHCs in a training program has been shown to improve hamstring strength by 11% and dynamic-control ratios in soccer players (Mjolsnes et al. 2004), The dosage of NHCs that Mjolsnes et al. (2004) was: – week 1: 1 session, 2 sets of 5 repetitions; week 2: 2 sessions, 2 sets of 6 repetitions; week 3: 3 sessions per week, 3 sets of 6-8 repetitions; week 4: 3 sessions, 3 sets of 8-10 repetitions; and weeks 5-10: 3 sessions, 3 sets of 12-10-8 repetitions.

NHCs also reduce the angle of peak torque (closer to full knee extension) (Clark and Weyand, 2014) for the hamstrings in athletic males, and reduce the incidence of hamstring injuries in various team-sport athletes during the season (Gabbe et al. 2006; Brooks et al. 2006 and Arnason et al. 2008). However, these studies have not been done with female athletes, so the results may differ slightly because of the lower-extremity morphology in females.

Another preventative strategy used to try and reduce the number of hamstring strain injuries is the FIFA 11+. This is a complete warm-up programme and can be used by players aged 14+. The programme was developed by FIFA Medical Group F-MARC, and its effectiveness has been proven in a scientific study (Bizzini and Dvorak, 2015). Teams that performed the FIFA 11+ at least twice a week had 30-50% fewer injured players (Soligard, et al. 2010). The programme should be performed as a standard warm-up, at the start of each training session at least twice a week and it takes around 20 minutes to complete.

The FIFA 11+ has three parts with a total of 15 exercises, these should be performed in the specified sequence at the start of each training session. The right technique should be used during all exercises to reduce the chance of injury. Full attention should be put on the correct posture and good body control, including straight leg alignment, knee-over-toe position and soft landings. The FIFA 11+ is broken down into 3 sections: part 1 – running exercises at a slow speed combined with active stretching and controlled partner contacts; part 2 – six sets of exercises, focusing on core and legs strength, balance, and plyometrics/agility, each with three levels of increasing difficulty; and part 3 – running exercises at moderate/high speed combined with planting/cutting movements (all sections of the FIFA 11+ can be found in appendix B) (FIFA 11+, 2011).

Another way to improve eccentric hamstring strength and try to reduce the number of hamstring strain injuries, the exercises should include as many of the following characteristics as possible: high forces, maximal muscle elongation, high velocities, multiple joint movements, closed-chain exercises, unilateral exercises and cost-effective and easily implemented exercises (Brughelli and Cronin, 2008). The exercises listed below are designed to implement as many of these characteristics as possible:

• Eccentric box drops: the athlete begins by stepping up onto a box (12 to 36 inches). He/she then steps off the box and lands in a squat position.
• Eccentric loaded lunge drops: the athlete rises onto his or her toes while taking a lunge stance, with or without a resistance. He or she then drops onto the ground with his/her feet landing flat and balanced. He or she will then resist the downward forces into a deep lunge position while maintaining good posture.
• Eccentric stiff leg deadlifts and concentric Romanian deadlifts: the athlete would perform a Romanian deadlift (RDL) with a barbell to get into the starting position. Then he/she performs a straight leg deadlift (SLD) during the eccentric phase (to the ground and reset for the RDL) and an RDL during the concentric phase (Brughelli and Cronin, 2008).

Rationale

This study is being carried out because a lot of previous literature is based specifically on male athletes, and so on football, basketball and rugby. There is not a lot of research done on female athletes, and evidently not on netball. Prevention strategies need to be developed to test the most effective training programs for netball and the optimum training periods required to provide the best protection against injury in netball. Also, eccentric hamstring weakness has been associated with a history of hamstring strains, and many studies have shown that eccentric hamstring training can reduce the incidence of hamstring strains. Most studies and research projects have been performed with professional athletes, and so the results may not be accurate for amateur athletes during training and the beginning of a netball season, when most injuries are likely to occur.

3. Method

The study is underpinned by a positivist paradigm and has adopted a quantitative approach. The positivist paradigm enabled a nomothetic approach to be endorsed. Kaboub (2008) has said that a positivist paradigm asserts that real events can be observed empirically and explained with logical analysis. A nomothetic approach was used because this research project attempted to establish general laws and generalisations. Nichols (2012) has said that the focus of a nomothetic approach is to obtain knowledge through scientific methods, therefore quantitative methods of investigation are used. They are used to try and produce statistically significant results.

14 female amateur University netball players, varying in ability (n=14, age SD = 19.7 ± 1.12, height SD =1.65 ± 0.04 and weight SD = 67.9 ± 6.5) were used for this study. In order to take part in the study, inclusion/exclusion criteria were enforced which included; the participants will have been free from hamstring injury for the past year, must be a member of the York St. John University netball club and must be physically active at least 2-3 times a week. Each participant would have also filled in a physical activity readiness questionnaire (PAR-Q) form (appendix C) and an informed consent form (appendix D). These were handed out before a training session. A gatekeeper consent form was also filled in by the netball coach (appendix E). The consent form included the research projects procedure, objective, an outline of the risks and benefits of the treatment plan, and would have offered the chance to ask any questions. All participants had the right to withdraw from the study at any point.

Before starting the treatment plan, all participants’ eccentric hamstring strength and flexibility were measured using an Isokinetic Dynamometer (IKD) and goniometer. This was done a week prior to starting the intervention, and was carried out in the morning, so all participants had not carried out any exercise or activity that could affect their final strength and flexibility readings.

Their strength was measured using an Isokinetic Dynamometer (IKD), and was done at two different speeds, 60 degrees per second and 180 degrees per second. The strength tests were done at these speeds because of the nature of the sport, in this case netball. The 60 degrees per second represents the strength aspect of the sport needed when going for a sprint, or when having to change direction quickly. The 180 degrees per second was used as this represented the power aspect of the sport. It replicated the muscle action when having to jump for the ball. Biodex (2017) stated that choosing angular velocities are important. Slow speeds are considered to be ‘strength speeds’ (60_­­⁰/sec to 120⁰/sec) and fast speeds (180⁰/sec to 300⁰/sec) are considered to be ‘endurance speeds.’

As netball is comprised of strength and endurance, the two assigned speeds can be compared with the demands of the sport. An IKD was used to collect each participants’ eccentric hamstring strength because the results obtained would be reliable and a valid measure. Drouin, et al. (2004) stated that the use of the IKD is very reliable, and that changes observed between measurements are due to differences in performance, instead of because of inconsistencies in the measuring capacity of the device.

Various studies demonstrated that there is a high test-retest reliability score performed when using an IKD (Almosnino, et al., 2012;Ayala, et al., 2012; Bandy and McLaughlin, 1993;Drouin, et al., 2004; Dirnberger, Kosters and Muller, 2012; Emery, Maitland and Meeuwisse, 1999;Impellizzeri, et al., 2008;Li, et al., 1996;Sole, et al., 2007). The findings in these articles suggest that you can rely on the readings produced from the IKD.

The data was then stored and saved using pseudonyms. Each participant sat on the IKD with a seat angle of 85 degrees. Once the participant was sat on the chair, it would be adjusted to their height, making sure that the axis of the IKD was in line with the lateral epicondyle of the knee, on the leg that was being tested. The leg that was not being tested was placed behind the contra limb stabiliser. The ankle and thigh straps were tightened, and the strength test commenced.

The flexibility of all the participants was measured by using a goniometer and by carrying out a straight leg raise (SLR). The goniometer gave an accurate reading of the participant’s flexibility. Nussbaumer, et al. (2010) have stated that manual goniometers can be used with confidence, they also found that the goniometers give a strong construct validity. It gave a reliable and valid reading because the SLR was done three times and an average was taken. Whilst carrying out the SLR, the participant was lying supine on the floor, the goniometer was placed on their greater trochanter, and their leg was raised as far as they could go, in full active extension. Their flexibility was written down and again kept stored using pseudonyms. The SLR is shown in figure 2.

Figure 2: SLR

Once their strength and flexibility was recorded, a familiarisation session of the NHC protocol was conducted. This provided an opportunity for the movements to be coached effectively, observed and any questions from participants to be answered.

The protocol for the NHCs was as follows, and can be seen in figure 3. It can be found in Sebelien, et al. (2014) and Potter, (2013):

1. the participants would kneel on a soft surface (i.e. a mat), and another netballer would hold down their ankles firmly, just above the ankle.

2. the body (torso) had to be completely straight from the shoulder to the knee whilst carrying out the exercise.

3. they would then have to lean as far forward as they could, controlling the movement with the hamstrings and gluteal muscles.

4. once the position could no longer be held, the weight would gently be taken onto the hands when falling into a push-up position.

Figure 3: NHC

The NHCs were carried out after a standard netball warm-up which consisted of: pulse raisers (i.e. 5 court jogs), dynamic stretches (focussing mainly on legs (i.e. quadriceps, hamstrings and calves), and some sport specific drills (i.e. four corners, chest passes, bounce passes and overhead passes).

In figure 4., four corners is illustrated. 20 passes receiving from the right side are done, followed by 20 passes receiving from the left. After four corners, 30 chest passes, 30 bounce passes and 30 overhead passes were done.

Figure 4: 4 corners

On a difficulty scale of 1-10, the NHCs should be between 7-9 (Syatt, 2015). In table. 1, the training regime used is shown, this has been adapted from Potter (2013);Turner, et al. (2014); Mjolsnes, et al., (2004)and Anastasi and Hamzeh (2011). Potter (2013) has proved that this dose of training is enough and has been very effective. 6-weeks is classified as a mesocycle, this has been widely acknowledged as crucial to optimising training responses (Gamble, 2006). The sets and repetitions changed every week to prevent plateaus and adaptation (Pelon, et al., 2009).

Table 1: NHC training regime

Week:	Repetitions:	Sets:	Frequency:
1	5	2	1
2	5	3	2
3	6	3	2
4	7	3	2
5	8	3	2
6	8	2	2

At the end of the 6-week programme, all participants had their eccentric strength and flexibility tested again, using the same protocol as prior to the treatment plan.

Data was analysed using Statistical Package for Social Sciences (SPSS). This allowed a dependent t-test (paired t-test) to be carried out. A paired t-test was used because it allowed the means of both groups (i.e. treatment group and the control group) to be compared, and so determined if there was a statistical significant difference between them both. Cohens-D was also done to determine whether or not the effect size could affect the results.  It is used to indicate the standardised difference between two means. If there is a difference (d) of 1, it means the two groups means differ by 1 standard deviation; a d of 0.5 means that the means differ by half of a standard deviation. Cohen suggested that when d=0.2 it is considered to be a ‘small’ effect size, 0.5 represents a ‘medium’ effect size and a 0.8 represents a ‘large’ effect size. This means that if two groups’ means don’t differ by 0.2 standard deviations or more, the difference is trivial, even if it is statistically significant. The equation used to work out the effect size is: Cohen’s D = (Mean₂ – Mean₁) / Standard deviation _pooled. Standard deviation pooled = √ [(S. D₁² + S. D₂²)/2].

4. Results

Tables 2 and 3 show the averages and standard deviations of both the treatment group and control groups strength data pre- and post-treatment plan. The raw data collected can be seen in appendix F.

Table 2: Descriptive statistics showing strength averages and standard deviations pre-treatment plan.

	TG60o/sec – pre-treatment plan	TG180o/sec – pre-treatment plan	CG60o/sec – pre-treatment plan	CG180o/sec – pre-treatment plan
Average	64	70.5	75	73.83
St. Dev.	± 12.88	± 12.61	± 14.95	± 7.98

Key:
TG – Treatment group, CG – Control group, 601 – 60^o/sec 1^st strength test, 602 – 2^nd strength test, 1801 – 180^o/sec, 1^st strength test, 1802 – 180^o/sec 2^nd strength test, F – flexibility, 1 – 1^st flexibility readings, 2 – 2^nd flexibility readings.

Table 3: Descriptive statistics showing strength averages and standard deviations post-treatment plan.

	TG60o/sec – post-treatment plan	TG180o/sec – post-treatment plan	CG60o/sec – post-treatment plan	CG180o/sec – post-treatment plan
Average	74.42	80.83	71	73.08
St. Dev.	± 14.41	± 16.33	± 14.17	± 11.54

Table 4: Results from paired T-test for strength data.

		Sig. (2- tailed), (P value)	Std. Deviation
Pair 1	TG601 – TG602	0.001	8.0955
Pair 2	TG1801 – TG1802	0	6.81353
Pair 3	CG601 – CG602	0.3	12.7422
Pair 4	CG1801 – 1802	0.82	11.13655

Table 4., shows the results from the paired T-test. It states that there was a significant difference in the treatment group before and after the 6-week intervention, as P (0.001 and 0.000) < 0.05 in both the 60^o/sec and 180^o/sec. There was no significant difference in the strength data in the control group when looking at their results before the 6-week treatment plan and after as P (0.300 and 0.820) > 0.05.

Figure 5: Graph showing average strength for both 60^o and 180^o/sec pre- and post-treatment plan.

Figure 5 is a bar graph showing the average strength of all participants before and after the treatment plan, at both degrees of speed (i.e. 60^o/sec and 180^o/sec).

Tables 5 and 6 show the descriptive statistics of both the treatment group and control groups first flexibility readings (before treatment plan) and second flexibility readings (after treatment plan).

Table 5: Descriptive statistics showing the averages and standard deviations of the flexibility readings pre-treatment plan.

	TG – Right leg flexibility – pre-treatment plan	TG – Left leg flexibility – pre-treatment plan	CG – Right leg flexibility – pre-treatment plan	CG – Left leg flexibility – pre-treatment plan
Average	116.5o	108.83o	112.67o	116.17o
St. Dev	± 11.06	± 8.99	± 15.56	± 22.10

Table 6: Descriptive statistics showing the averages and standard deviations of the flexibility readings post-treatment plan.

	TG – Right leg flexibility – post-treatment plan	TG – Left leg flexibility – post-treatment plan	CG – Right leg flexibility – post-treatment plan	CG – Left leg flexibility – post-treatment plan
Average	110o	105.33o	122o	118.83o
St. Dev	± 14.07	± 17.15	± 10.71	± 9.97

Table 7: Results from paired T-test for flexibility data.

		Sig. (2- tailed), (P value)	Std. Deviation
Pair 1	FTG1 – FTG2	0.008	7.16208
Pair 2	FCG1 – FCG2	0.015	9.3042

In table 7, the paired T-test for the flexibility data is shown. The results show that there was a significant difference in the treatment group, between the first set of flexibility readings (before treatment plan) and the second (after the 6-week treatment plan), as P (0.008) < 0.05. There was no significant difference in the flexibility of the control group as P (0.15) > 0.05.

Figure 6: Graph showing average flexibility in the TG both pre – and post – treatment plan.

Figure 6 is a bar graph showing the average flexibility in the treatment group in both the pre- and post-treatment plan. It shows that the flexibility in both legs improved after the NHCs were carried out.

Cohen’s D for the strength variable is 0.39. This means that there is a ‘small’ effect size.

Cohen’s D for the flexibility variable is 0.99. This means that there is a ‘large’ effect size.

5. Discussion

The aim of the study was to compare, discuss and analyse whether or not a 6-week intervention programme consisting of NHCs had a positive effect on eccentric hamstring strength and flexibility in amateur netball players.

The main finding of the study was that the 6-week Nordic hamstring curl treatment plan did increase the eccentric hamstring strength and flexibility, proving that the intervention did work. So, the answer to the research question is, yes, Nordic curls do have an influence on eccentric hamstring strength and flexibility. The results from carrying out the T-test showed that there was a significant difference in eccentric hamstring strength and flexibility in the treatment group after the 6-week treatment plan which consisted of NHCs. They are significant because P (0.001 and 0.000) < 0.05, in both the 60 degrees per second and 180 degrees per second speeds on the IKD. Figure 5 clearly shows the difference in eccentric hamstring strength pre- and post-treatment plan in the treatment group, in both 60^o/sec and 180^o/sec.

However, as the control group was not receiving any treatment or preventative strategy, their results were not significant. This is shown because P (0.30 and 0.82) > 0.05. The results in the flexibility variable in the treatment group were also seen as significant because P (0.008) < 0.05, whereas, the control group did not have a significant difference as P (0.015) > 0.05. The bar graph in figure 6 shows the drastic change in flexibility in both the right and left leg pre- and post-treatment plan.

Cohen’s D showed that there was a ‘small’ effect size (0.39) in the strength variable, this means that although there was a significant difference, the magnitude of change was evidently small. Cohen’s D effect size for the flexibility variable was 0.9, which has been shown to be a ‘large’ effect size. This shows that the magnitude of change was large, even if the sample size was relatively small.

As there was a significant difference in both the eccentric strength and flexibility in the treatment group, the alternative hypothesis can be accepted, and the null hypothesis would be rejected.

The results of the study agree with previous literature that Nordic Hamstring Curl training has a positive effect on eccentric hamstring strength. Studies by Arnason et al., (2008); Askling, Karlsson and Thorstensson (2003); Petersen et al., (2011); and Van der Horst et al., (2015) have proved that eccentric hamstring strength training is an effective way to decrease the number of hamstring strain injuries. The causes of hamstring strains are multifactorial in nature, and it has been stated that most hamstring strain injuries result from the interaction of several risk factors (Opar, Williams and Shield, 2012). These risk factors can be divided into non-modifiable (i.e. those that cannot be altered): prior injury, age and ethnicity; and modifiable risk factors (i.e. those that can be altered): strength, strength imbalances, muscle fascicle length, fatigue and load management.

Strengthening the hamstrings is important as injuries normally occur in the latter part of the swing phase during sprinting, running or jogging. This is when the hamstrings are (sub)-maximally stretched. This is because of hip flexion and knee extension. The hamstring muscles must decelerate knee extension (i.e. performing an eccentric contraction in a lengthened position) (Chumanov, Heiderscheit and Thelen, 2011; and Chumanov, Heiderscheit and Thelen, 2011). Various studies (Croisier et al., 2002; Croisier et al., 2011; and Opar, Williams and Shield, 2012) have shown that the risk of suffering from a hamstring strain during high-speed running is linked to inadequate eccentric hamstring strength. Koulouris et al. (2007) stated that high rates of hamstring injury recurrence is arguably the most concerning aspect of hamstring strain injuries. This is because re-injuries tend to be more severe, and so, result in more time-loss than the original injury.

Bourne (2016) has stated that increasing knee flexor strength by performing eccentric hamstring strength lowers (NHCs) will improve the ability of the hamstrings to withstand high loads, such as those experienced in the injurious late-swing phase of running. Beyond simply improving strength, eccentric strength training can also provide benefits in the form of improved damage resistance of the hamstrings. Bourne (2016) has also proved that repeated bouts of eccentric training have been shown to increase the length of muscle fascicles, which can significantly reduce the risk of hamstring strain injuries. Timmins et al., (2015) found that professional soccer players with short hamstring fascicles were, on average, four times more likely to tear their hamstring than those with longer fascicles.

The study by Timmins et al. (2015) proved that a 0.5cm increase in fascicle length was sufficient to reduce injury by 74%. Despite significant research being done on hamstring injury rates and the effort to try and reduce the burden of these injuries in sport, longitudinal data from the elite Australian football league (Orchard and Seward, 2002), elite level soccer (Ekstrand, Hagglund and Walden, 2009; Ekstrand, Hagglund and Walden 2016) and athletics (Opar et al. 2013), suggest that hamstring injury rates are not on the decline. A recent survey of the UEFA Premier League suggests that hamstring injuries have increased by 4% over the past 13 years (Ekstrand, Hagglund and Walden, 2016). The time lost from training and competition is not only challenging for the athlete and the team, but it can also impart a large financial burden on clubs. Hamstring strain injuries have been estimated to cost English Premier League clubs £74.4 million each season.

Because of the acceleration/deceleration nature of netball as a sport, the results in the above-mentioned studies can be transferable. This means that hamstring strain injuries suffered by netballers can potentially result in them missing games and having to pay a substantial amount of money to rehabilitate the injured muscle.

Flexibility has been stated to be a factor in determining whether or not an athlete is likely to suffer from a hamstring strain injury (Mendiguchia, Alentorn-Gell and Brughelli (2012). Athletes with poor hamstring flexibility may have shorter optimum hamstring muscle lengths in comparison to athletes with normal hamstring flexibility. Liu et al., (2012) have proved that shorter optimum muscle length may result in higher muscle strain for the same range of motion, and so, increase the risk of hamstring strain injury. However, results from previous studies have been shown to be inconsistent.

Studies by (Yeung, Suen and Yeung, 2009; Rhea et al., 2003; Bahr et al., 2010; and Orchard et al., 1997) have shown that there is no significant difference in different hamstring flexibilities prior to hamstring muscle strain injuries between injured and non-injured athletes. On the other hand, a study by Gabbe, Branson and Bennell, (2006) showed that elite Australian football players who had recurring hamstring strain injuries appeared to have better hamstring flexibility in comparison to their counterparts without recurrence of the injury. The inconsistency among these studies could be because of differences in sample sizes, and injury risk measures in study designs.

5.1 Limitations

Whilst carrying out the research project several setbacks were met. A limitation which was met whilst carrying out the study was the lack of adherence to the study. Because of the length of the intervention (i.e. 6-weeks) many of the participants did not carry out the whole treatment plan. Various participants did not carry out the whole treatment plan because they were complaining about ‘delayed onset of muscle soreness’ (DOMS). Many of them thought that it would affect their performance in midweek matches. In order to collate, collect and try to get an accurate representation of the results from the treatment plan, the participants which had taken part in 80% or more of the sessions were used; this resulted in the sample size being even smaller.

Leaving a sample size of only 12 participants; six of these carrying out the treatment plan and the other six being in the control group. As the sample size was so small, the results obtained can be seen as unreliable, and may lack validity. This could also mean that the results may lack statistical representation. Although the results were significant, as the effect size was so small in the strength variable and in the flexibility component of the study, the difference is unimportant.

The use of the isokinetic dynamometer also affected the study. Although it is the gold standard tool for assessing eccentric hamstring strength, its widespread application is limited. This is because the device is largely inaccessible and expensive to purchase (Opar et al., 2015). This affected the study because the participants were not used to the movements and demands put on them by the machine. As it is a very uncomfortable, and an unnatural movement and a strenuous process, the results may not be representable. This could have affected the effort the participants put into the NHC’s as they could be suffering from ‘delayed onset of muscle soreness’ (DOMS).

Another setback is the fact that any extra exercise done by both the treatment group and the control group could not be controlled. This could mean that the participants strength data could have changed because of individual training they could have done throughout the intervention. This means that the NHCs may not have been the only factor that had an influence on eccentric hamstring strength and flexibility in the participants.

The fifth limitation of the study was the fact that only one level of netball was looked at (i.e. amateur). Research by Chandler et al., (2014) has stated that there are differences in physical demands between playing standards. Cormack et al., (2013) found that there is a greater play load across all playing positions in netball of higher standards. The findings from this study suggest that the movement demands of netball are greater at the elite level than at the sub elite level, meaning that the results from this research project may not be transferable to other sporting populations.

5.2 Future research

There is a lack of research on netball and the demands and implications suffering from an injury can have on an athlete. The lack of studies pertaining to netball poses challenges for evidence-based training prescriptions. The data that exists at this point points directly to the importance of appropriate physical preparation for netball players from the point of view of guarding the athletes against injury. Due to the fact that only 14 amateur netballers were used in this study, future researchers could use a larger sample size to increase validity of the results obtained.

The treatment plan could also be used with different levels of netball players, as this would enable the researchers to see whether or not the Nordic hamstring curls would have a positive effect on them. Also, there may be another method to measure eccentric hamstring strength other than the IKD, as this instrument is likely to put the athlete under unnecessary stress, and can potentially hinder the amount of effort they put on the actual treatment plan. Further research should also be carried out with a follow-up, in order to enable the long-term effects of the NHCs to be analysed and the effectiveness they have on recurrent hamstring injuries in amateur sporting populations.

Further studies with improved research designs are needed to determine the effects that flexibility can have on the risk of hamstring muscle strain injury. As stated by Klugl et al., (2010), there is a lack of research on the implementation and effectiveness of injury preventative strategies in a real-world context. This is essential as positive study outcomes do not always directly translate into injury prevention.

6. Conclusion

The results from the study agree with previous literature which state that Nordic hamstring curls are an effective strategy to reduce the number of hamstring strain injuries in sport. The 6-week treatment plan of Nordic hamstring curls evidently has a positive effect on eccentric hamstring strength and flexibility in amateur netballers. However, because of the nature of the sport, the results could be transferable with other sports with similar demands, such as football or basketball. As they have had a positive effect on eccentric hamstring strength and flexibility the alternative hypothesis can be accepted and the null hypothesis rejected. The answer to the research question is yes, Nordic hamstring curls do have a positive influence on eccentric hamstring strength and flexibility in amateur netballers.

6.1 Practical implications

• This study is the first to look at the effect that a 6-week Nordic hamstring curl treatment plan has on eccentric hamstring strength and flexibility in amateur netball players.
• Amateur netball players would be able to implement the treatment plan into their training programmes as the exercise does not need any equipment and can be done simultaneously.

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Appendices

		Page
Appendix A	Netball court	52
Appendix B	FIFA 11+	53
Appendix C	PAR-Q form	54
Appendix D	Informed consent form	56
Appendix E	Gatekeepers consent form	58
Appendix F	Raw data collected for strength data and flexibility	60
Appendix G	Meetings with Supervisor	62

Appendix A

GK

WD

GD

C

WA

GA

GS

Appendix B

Appendix C

Name			Sex
Risk Factors: Two or more risk factors places the client at moderate risk
Have any parents, brothers or sisters had a heart attack, bypass surgery, angioplasty, or sudden death prior to 55 years (male relatives) or 65 years (female relatives)				Yes	No
Have you smoked cigarettes within the past 6 months?				Yes	No
Do you take blood pressure medication				Yes	No
Do you get at least 30 minutes of moderate physical activity or equivalent per day?				No	Yes
R   Resting blood pressure; SBP = _______ mmHg, DBP = _______ mmHg				 140/90	< 140/90
Total cholesterol   = _______ mmol.l-1				 5.2	< 5.2
Fasting glucose = _______ mmol.l-1				 5.6	< 5.6
Body mass index = _______ kg.m-2				 30	< 30
Waist girth = _______ cm Males				 102	< 102
Females				 88	< 88
TOTAL NUMBER OF RISK FACTORS
Symptoms: One or more places the client at high risk
Do you ever have pain or discomfort in your chest or surrounding areas?				Yes	No
Do you ever feel faint or dizzy (other than when sitting up rapidly)?				Yes	No
Do you find it difficult to breathe when you are lying down or sleeping?				Yes	No
Do your ankles ever become swollen (other than after a long period of standing)?				Yes	No
Do you ever have heart palpations, or an unusual period of rapid heart rate?				Yes	No
Do you ever experience pain in your legs				Yes	No
Has a doctor ever said you have a heart murmur? (If yes has he/she said it is ok for you to exercise?)				Yes	No
Do you feel unusually fatigued or find it difficult to breathe with usual activities?				Yes	No
TOTAL NUMBER OF SYMPTOMS
Other

Age = _______ years (Males  45, females  55 are at moderate risk)	Male	 45	< 45
	Female	 55	< 55
History of disease or current disease (yes to any places client at high risk)
Heart disease		Yes	No
Peripheral vascular disease		Yes	No
Cerebrovascular disease		Yes	No
Chronic obstructive pulmonary disease (emphysema/chronic bronchitis)		Yes	No
Asthma		Yes	No
Interstitial lung disease		Yes	No
Cystic fibrosis		Yes	No
Diabetes mellitus		Yes	No
Thyroid disorder		Yes	No
Renal disease		Yes	No
Liver disease		Yes	No
Do you have any bone or joint problems such as arthritis or a past injury that might get worse with exercise? (Exercise testing may need delaying or modifying)		Yes	No
Do you have a cold or flu, or any other infection? (Exercise testing must be delayed)		Yes	No
Are you pregnant? (Exercise testing may need delaying or modifying)		Yes	No
Do you have any other problem that might make it difficult for you to do strenuous exercise? Details:		Yes	No
Have you consumed alcohol in the last 24hours			No
Confidential Comments
Risk Analysis
Low risk: Young and no more than one risk factor can do maximal exercise testing or enter a vigorous programme Moderate risk: Older and 2 or more risk factors can do submaximal testing or enter a moderate programme High risk: One or more symptoms of disease or disease cannot do any testing without physician clearance
Client Signature:	Date:
Assessors Signature:	Date:

Appendix D

Information Sheet

Invitation to Participate

You have been invited to take part in a research project on the effect that Nordic Hamstring Curls have on eccentric hamstring strength and flexibility in Netballers. Before you decide whether or not to take part, it is important that you understand why the research is being done and what it will involve. Please take time to read this information carefully and discuss it with others if you wish.

How does the study involve me?

Part of this study involves taking part in a 6-week treatment plan consisting of Nordic Hamstring Curls. This will only be carried out twice a week and will be done during the netball training sessions.  Eccentric hamstring strength and flexibility will be measured once at the beginning of the plan and once at the end to see if there has been an increase or not.

Section 1: Will have a taster session to go through the protocol of a Nordic Hamstring Curl and to get used to the isokinetic dynamometer.

Section 2: The treatment plan would commence and data would be collected.

Do I have to take part?

No. It is up to you whether or not you take part in this study, although your contribution would be extremely appreciated. If you decide to take part, you may withdraw at any time without giving a reason. If you withdraw from the research any words used by you will be removed from the data analysis.

Will my taking part in this study be kept confidential?

All data collected will be confidential and kept safe on SPSS, in order for the researcher to analyse it. Pseudonyms will be used for you and people you mention in order to maintain anonymity.

Informed Consent Form

Please tick () all boxes and date and sign where indicated below (X):

A. I confirm that I have read and understood the information sheet for the above study and understand what is expected of me   ☐

B. I confirm that I have been given the opportunity to ask questions regarding the study and, if asked, my questions were answered to my full satisfaction ☐

C. I understand that my participation is voluntary.  I also understand that I may withdraw at any time without giving a reason for my withdrawal and without penalty ☐

D. I understand that all information about me will be treated in strict confidence and that, I will not be named in any written work arising from this study ☐

Your name (PRINT)		Date		Signature X
Researcher’s name (PRINT)		Date		Signature

Data Protection Act

I understand that data collected about me during my participation in this study will be stored on a password-protected computer and that any files containing information about me will be made anonymous.

Signature: ____________________________ Date: ______________

Appendix E

Dear ,

As part of my undergraduate dissertation module I am completing a research project on The effect 6-week Nordic Hamstring Curls have on eccentric hamstring strength and flexibility in netballers. I request your permission to use the York St. John Netball club to complete my research study.

What does the study involve?

My study will involve 20 netballers completing a 6-week treatment plan consisting of Nordic Hamstring Curls. The netballers I will be using will be in the 3^rd, 4^th and 5^th team. I will be testing their eccentric hamstring strength by using an isokinetic dynamometer and their flexibility by using a goniometer. I am going to be doing this research project as hamstring strains are one of the most common injuries suffered by netballers.

What happens with the study findings?

Only myself and my dissertation supervisor will have access to the information from this study. Pseudonyms will be used for all participants and named people and organisations in the study.

Who can I contact if I have any questions?

My details are at the top of the page. Alternatively, contact my supervisor.

I have read and understand the above information and do give my consent to this study taking place.

Print Name: ………………………………………………   Date: ……………………………….

Signature: ………………………………………………………………

Appendix F

Data for first strength test:

CG:	60o/sec (right leg)	60o/sec (left leg)	180o/sec (right leg)	180o/sec (left leg)
1	81	83	79	85
2	75	85	79	76
3	80	61	68	75
4	60	54	72	57
5	103	87	85	73
6	77	54	71	66
TG:
7	61	56	65	64
8	89	64	88	68
9	43	49	47	53
10	68	62	79	71
11	68	83	73	85
12	57	68	68	85

Data for second strength test:

CG:	60o/sec (right leg)	60o/sec (left leg)	180o/sec (right leg)	180o/sec (left leg)
1	77	76	73	79
2	72	85	67	68
3	79	60	68	85
4	61	47	75	56
5	77	61	75	71
6	99	58	100	60
TG:
7	71	66	79	81
8	92	75	110	72
9	45	53	57	54
10	84	91	85	88
11	80	87	73	99
12	77	72	76	96

Data for first flexibility test:

	Right leg (o)	Left leg (o)
CG:
1	98	102
2	105	95
3	124	135
4	98	99
5	137	150
6	114	116
TG:
7	103	99
8	113	101
9	123	115
10	127	114
11	128	121
12	105	103

Data for second flexibility test:

	Right leg (o)	Left leg (o)
CG:
1	97	88
2	101	95
3	124	124
4	98	89
5	130	126
6	110	110
TG:
7	122	126
8	117	105
9	133	133
10	124	115
11	132	121
12	104	113

Appendix G

Date/ Time of Meeting	Purpose of the Meeting	Description of Meeting	Outcomes of the Meeting	Agreed Action Plan and Next meeting Time Frame
23rd Sept 2016 @ 14:30	To propose and confirm whether my idea/title is good enough as a dissertation.	Showed poster proposal.	Agreed on action plan and what I will have done for the next meeting.	Look for articles to start off my literature review.   Will arrange another meeting for two weeks’ time.
14th Oct 2016 @ 16:00	To confirm and adjust my dissertation idea and see if anything should be changed	Spoke about the equipment that is going to be used and who the participants are going to be. Also, decided to add to the variables being tested and worked on i.e. flexibility.	Decided to add flexibility as the Nordic Hamstring Curls are likely to affect this too. It will also make the time in the lab more efficient as I could be measuring participants’ flexibility using the FMS whilst measuring peoples eccentric hamstring strength using the IKD.	Find articles and literature that will help me when I need to write my review of literature.
29th Nov 2016 @ 13:50	To go over what needs to be included in my literature review, and come up with a plan.	Wrote down all that needs to be included in review of lit.	Came out with a structured plan and a clear idea as to what I should include.	Have a draft of my literature review for the next time I meet Jamie.
6th Feb 2017 @ 13:25	Check if literature review is on the right tracks.	Read over the first half of lit review, to check structure and what I have included already.	Set myself deadlines for intro, method and lit review.	Literature review finished, introduction and method draft for 20th February.
20th Feb 2017 @ 14:15	Check if introduction, literature review and method are on the right tracks.	Read over the first draft of introduction, literature review and method.	Jamie gave me a couple of corrections to make.	Make amendments and finish the 3 sections.
27th March 2017 @ 13:50	Ask questions on corrections given on 1st draft.	Jamie explained what he meant by the comments given. Also, explained how to carry out statistical tests.	Clear understanding of what is needed in introduction, lit. review and method. Also know what and how to run the statistical tests.	To have completed all corrections and get results and discussion done as soon as possible.
24th April 2017 @ 13:20	Final guidance on results and discussion.	Jamie explained what he expected/wanted in the results and discussion.	Clear understanding of what was expected.	Completed and submitted dissertation!