In Patients with Acute Muscle Strain is Cold Therapy or Heat Therapy More Effective for Initial Relief of Symptoms?
Acute muscle strain is a common injury among athletes, members of the workforce and the general population. Conflicting advice regarding the application of cold or heat for initial therapy is given across medical disciplines. This research was undertaken in an attempt to obtain evidence of which approach is more beneficial to patients.
Using computer based searches of the on-line libraries at University of Texas Rio Grande Valley and Yale University, numerous data bases were accessed. Key word searches were, for the most part, straightforward but then branched out using information obtained in the primary search. Two articles reviewing the pathophysiology of muscle strain were deemed important for background understanding of muscle strain. The studies on this topic are limited and current research is sparse. Thirty two articles were originally obtained and reviewed with ten being selected for use in this paper.
Results show that each modality has benefits in the acute phase of treatment. Benefits of both cold and heat application were shown by outcomes and conclusions of the various studies. Understanding the mechanisms of cold and heat applications in acute muscle strain injury substantiate the conflicting results.
There is no conclusive evidence in favor of cold over heat therapy in the initial treatment of acute muscle strain for relief of acute symptoms. It is shown through these limited studies that in acute muscle strain, both cold and heat therapy can be beneficial. Both are inexpensive, easy to obtain and use. Some patients have strong feelings about what works best for them and with effective patient education either can be recommended. The ultimate decision and favorable outcomes rely on clinician judgment on a case by case basis combined with patient education and patient choice.
Acute muscle strains are common injuries across the general population. Members of the workforce, professional athletes and weekend warriors may have a higher incidence, but at some time in most peoples’ lives, they will suffer from this type of injury. The longstanding confusion regarding the use of ice or heat for acute muscle strain persists to this day. In an attempt to research this question and understand the theory behind each treatment option, background of the cause of such injuries is traced down to the cellular level.
Acute muscle strains start with muscle fibers being torn as the result of overstretching of the fibers and rupture of the myofibers. This tearing causes hematoma between the ruptured fibers and an inflammatory cell reaction.1 The inflammation leads to increased intramuscular pressure which compresses the muscle, limiting the size of the hematoma.1 The use of ice is thought to further decrease the size of the hematoma which in turn causes less inflammation which promotes with earlier cell regeneration.1 Ice application in acute muscle strain is shown to decrease pain by various means including decreasing blood flow to the injured tissues thereby decreasing edema, inducing a “local anesthetic effect” and also decreasing spasm.2 On the other hand, the application of heat is found to cause vasodilatation which assists in decreasing pain by increasing blood flow to the fibers.2 This also increases the elasticity of the fibers, increases the delivery of oxygen and nutrients to the cells and increases the rate of healing by increasing cell metabolism.2
This knowledge of the mechanisms by which both cold and heat therapy work helps to form an understanding of the conflicting evidence gathered. The respective studies for each modality are few in number and limited in scope. The evidence gathered substantiates the perpetuation of conflicting advice among healthcare providers
On-line libraries at University of Texas Rio Grande Valley and Yale University, as well as Google Scholar sites were reviewed using search terms including the entire PICO question “In Patients with Acute Muscle Strain is Cold Therapy of Heat Therapy More Effective for Initial Relief of Symptoms”, “acute muscle strain”, “heat therapy” and “cold therapy”. Two articles reviewing the pathophysiology of muscle strain were used for background understanding of pathophysiology muscle strain. Only one study dealt with a study of muscle strain and the effects of heat and cold at a cellular level. Two studies were randomized controls using medication, heat and cold therapies. A Cochrane Review article referenced most other articles found. Three articles found were sponsored by a company that manufactures portable heat wraps and were eliminated from this group. Thirty two articles were originally obtained and reviewed with ten being used for this paper.
Results show that each modality has benefits in the acute phase of treatment. Ice is shown to decrease pain by various means including decreasing swelling and providing a numbing effect.2 The mechanisms for pain relief with heat are attributed to increasing elasticity of the muscle fibers and decreasing spasm among others.2
With conflicting evidence and limited studies, there is no clear answer to the question posed. One study found concluded “cryotherapy is better than heat for treating acute muscle strain” noting “significant reduction in pain at rest, pain with movement, and functional disability at intervals of 7, 14, and 28 days postinjury”3. While another notes that the favorable results of ice application stem from decreased metabolism in the tissues which results in decreased hypoxic injury to the cells.4 Another study finds that “moderate-quality evidence showed that a heat wrap moderately improved pain relief (at 5 days)”.5
One randomized clinical trial used two cohorts, a patient education only group compared with a patient education combined with continuous low-level heat application. The study evaluated relief of pain and decrease in disability in workers with acute low back pain. Data collected included pain intensity, pain relief and disability scores. The conclusion was that “topical heat therapy had significantly reduced pain intensity, increased pain relief, and improved disability scores during and after treatment”.6 Of note, no sponsorship of conflict of interest was disclosed in this article, but a name brand heat wrap was utilized in this study.
Two studies were found that combined randomized trials of heat and cold combined with a non-steroidal anti-inflammatory medication. In one randomized controlled trial sixty patients with acute neck or back strain were given 400 mg. of ibuprofen and then randomized to 30 minute application of heating pad or cold pack. The conclusion was that both modalities resulted in “a mild yet similar improvement in the pain severity” but also noted the benefit could have been from the ibuprofen.7 It was noted that “Choice of heat or cold therapy should be based on patient and practitioner preferences and availability”.7 The other study was a randomized control trial with three groups. Group one utilized heat application and naproxen, group two used cold application and naproxen and group three only took naproxen. Expanding on the study where only two groups were compared, this gave the extra control of a purely non-steroidal anti-inflammatory group in order to see if the additional topical therapies were more effective than just the medication. Data gathered included examination and pain questionnaires. Results were tracked at 0, 3, 8 and 15 days. The conclusion of this study was that both “thermotherapy and cryotherapy caused low back pain to be relieved” and both groups had slightly better results that the medication only group.8
The one study that looked at cellular changes in acute muscle strain identified oxidative damage to the cells immediately following muscle strain.9 The findings concluded that “Although heat and cold alone and in combination decreased the muscle and blood oxidative damage, the therapeutic cold treatment seems to be more effective in preventing the damage induced by a strain injury. We believe that the greater beneficial effects of the cold treatment are possibly related to its capacity to control the impairment of muscle cell structure and also to modulate the intensity of the inflammatory response that follows a muscle strain injury”.9 As noted, this was a scientific study on the cellular level and an assumption was made as to the correlation of therapeutic effect and pain relief in actual human injuries.
Most studies pointed out the fact that there is limited data regarding the use of either modality in treating acute muscle strain2,10 and that need for more randomized control trials of high-quality along with studies of treatment and utilization of cold and heat for acute muscle strains are necessary. 2,4
There is limited evidence for either heat or cold therapy for acute muscle strain. Studies investigating heat alone showed favorable results as did studies only looking at the effects of cold. In two trials where heat and cold were investigated side by side, both were found to be beneficial. Many more high quality trials are needed to provide evidence based guidelines in the initial treatment of acute muscle strains.
The continual question of heat versus cold is perpetuated with good reason. There is no compelling evidence that one treatment is more helpful than the other. In acute muscle strain, both cold and heat therapy can be beneficial. Both are inexpensive therapies, easy to obtain and use. For cold therapy application of ice with a towel between the ice and skin is the most common modality but if none is available, a cool compress will be of some benefit. For heat therapy, some patients prefer heating pads or special packs that can be heated in the microwave, but no special equipment is needed. Patients can be advised to use a hot pack by soaking a towel in warm water and applying to the affected area. If they chose to use a heating pad, they should be cautioned regarding the risk of burns to the skin if used for a prolonged period. Applications of either cold or heat should be for no more than 15 to 20 minutes at a time.
The persuasive yet limited research on both modalities leaves the ultimate decision up to the individual patient as to what works best for them. Some patients have strong objections to certain treatments. There are patients that will not use ice stating that the cold makes their muscles feel stiff while other patient object to the use of heat noting that the application of heat makes the area burn more. In garnering the evidence that exists, either modality can be recommended based on patient choice along with clinician judgment and thorough patient education of the options. It is up to the clinician to provide the patient with the relevant information to make an informed decision. It only takes a few minutes to explain the technique for application of either cold or heat, the theory behind each modality and the pros and cons of each treatment. Explain that they may try both and continue with whichever treatment gives them the most relief. This gives them sound medical advice and options which will help the patient be an active participant in the treatment plan for their acute muscle strain injury.
1. Järvinen TAH, Järvinen TLN, Kääriäinen M, Kalimo H, Järvinen M. Muscle Injuries:Biology and Treatment. 2005;33(5):745-764.
2. Malanga GA, Yan N, Stark J. Mechanisms and efficacy of heat and cold therapies for musculoskeletal injury. Postgraduate Medicine. 2015;127(1):57-65.
3. Martin SN, Paulson CP, Nichols W. Does heat or cold work better for acute muscle strain? In. Journal of Family Practice. Vol 572008:820+.
4. Scott A, Khan KM, Roberts CR, Cook JL, Duronio V. What do we mean by the term “inflammation”? A contemporary basic science update for sports medicine. 2004;38(3):372-380.
5. Qaseem A, Wilt TJ, McLean RM, Forciea M, for the Clinical Guidelines Committee of the American College of P. Noninvasive treatments for acute, subacute, and chronic low back pain: A clinical practice guideline from the american college of physicians. Annals of Internal Medicine. 2017;166(7):514-530.
6. Tao XG. A randomized clinical trial of continuous low-level heat therapy for acute muscular low back pain in the workplace. Journal of occupational and environmental medicine.47(12):1298-1306.
7. Garra G, Singer AJ, Leno R, et al. Heat or Cold Packs for Neck and Back Strain: A Randomized Controlled Trial of Efficacy. 2010;17(5):484-489.
8. Dehghan M, Farahbod F. The Efficacy of Thermotherapy and Cryotherapy on Pain Relief in Patients with Acute Low Back Pain, A Clinical Trial Study. Journal of Clinical and Diagnostic Research : JCDR. 2014;8(9):Lc01-04.
9. Carvalho N, Puntel G, Correa P, et al. Protective effects of therapeutic cold and heat against the oxidative damage induced by a muscle strain injury in rats. Journal of Sports Sciences. 2010;28(9):923-935.
10. French SD, Cameron M, Clarke RB, Esterman A, Reggars J, Walker B. Superficial heat or cold for low‐back pain. Cochrane Database of Systematic Reviews. 2004(2).
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