Recommendations for the Avoidance of Delayed-Onset Muscle Soreness

National Strength & Conditioning Association Volume 23, Number 4, pages 7 13 Recommendations for the Avoidance of Delayed-Onset Muscle Soreness David J. Szymanski, MEd, CSCS Department of Health and Human Performance Auburn University Keywords: delayed onset muscle soreness; eccentric exercise; eccentric muscle action; muscle damage; repeatedbout effect; warm-up. TO INCREASE STRENGTH OR enhance aerobic performance, individuals need to place greater demands on their bodies by overloading their muscles or cardiovascular system with progressive exercise. When the intensity of the exercise is more than the body is accustomed to, muscle pain and stiffness can occur. Many novice and well-trained athletes adopt the "no-pain, no-gain" mentality to increase their strength or aerobic performance. However, when this pain is associated with injury, it may lead to a decrease in performance and impede strength gains for as long as 3 weeks (6). Everyone, regardless of his or her fitness level, has experienced sore and stiff muscles after moderate to strenuous exercise or at the beginning of a new exercise program. These symptoms of muscle soreness and stiffness occur after eccentric or unaccustomed exercise (1, 4, 6, 16, 19). Eccentric muscle actions, such as performed in downhill running, plyometrics, and the high-force downward phase of the bench press, occur when the tension in the muscle is less than the resistive force. As a result, the muscle lengthens despite tension being produced (1, 4, 6, 16, 19). Greater tension in the muscle is generated eccentrically as compared with the case of either concentric or isometric exercise (8). Also, fewer muscle fibers are recruited to produce a greater force during eccentric actions. Thus, muscle fibers are more susceptible to ultrastructure damage (1, 6, 16). This damage can lead to muscle soreness, loss of strength, decreased range of motion (ROM), and a temporary decrease in neuromuscular function (1, 2, 4, 6, 16, 19). All of these symptoms together are generally referred to as delayed onset muscle soreness, or DOMS. The cause of DOMS was investigated as early as 1902 by Hough (14). Since then, a number of possible explanations have been proposed, including the buildup of lactic acid in muscle, increased intracellular calcium concentration, increased intramuscular inflammation, and muscle fiber and connective-tissue damage (1, 3, 6, 16, 19, 31). DOMS is the pain, tenderness, deep muscle aching, and stiffness that begins 8 12 hours after eccentric or unaccustomed exercise. It peaks from 24 72 hours after exercise and dissipates 5 7 days after exercise (1, 4, 6, 7, 10, 16, 19). The magnitude of DOMS is related to both the intensity of the muscular actions and the duration of the exercise. Of the two, intensity appears to cause a more pronounced effect (1, 6, 34). Although the precise cause of DOMS remains unknown, this paper will describe possible causes of DOMS and suggest methods to reduce it. Possible Causes of DOMS The most commonly believed cause of DOMS in the lay community is lactic acid accumulation in the muscles. Although this explanation is popular, the soreness that results from intense eccentric exercise is not related to lactic August 2001 Strength and Conditioning Journal 7

Figure 1. Time course for the effects of recovery on blood lactate removal after intense exercise (24). Note that lactic acid can be removed from the blood much more quickly if the subject performs continuous light exercise instead of no exercise. Legend: solid line, no exercise; dashed line, light exercise (35% VO 2 max); dotted line, resting baseline. acid (1). Blood and muscle lactate levels typically return to normal values 30 60 minutes after exercise (12). Eccentric exercise, which produces the largest amount of muscle soreness, requires a relatively low energy expenditure. Eccentric exercise utilizes about one-third less oxygen and forms less lactate than concentric exercises at the same power (1). Also, the energy used (per unit area of active muscle) is less in eccentric exercise than in concentric exercise (1). Thus, if lactic acid were the cause of DOMS, then muscle soreness would be expected to be greater after exercise with a higher metabolic cost (concentric exercise). Schwane et al. (29) reported that downhill running (a form of eccentric exercise), compared with level running at the same speed, produced less lactic acid and greater severity of the symptoms related to DOMS. Furthermore, Fitzgerald et al. (12) stated that the time course for changes in lactate concentration and the perception of muscle soreness do not coincide. Blood and muscle lactate levels usually return to baseline values 30 60 minutes after exercise, whereas DOMS is not perceived until 8 12 hours after exercise and peaks from 24 72 hours after exercise (12). Figure 1 shows the effects of recovery on blood lactate removal after intense exercise. If a subject performs continuous light exercise (35% V o 2 max) during recovery as compared with engaging in a resting recovery (no exercise), lactic acid removal from blood occurs within 40 minutes instead of 60 minutes (24). Figure 2 illustrates the time course of muscle soreness following eccentric exercise. Because peak DOMS is experienced 24 72 hours after eccentric exercise and because lactate concentrations return to pre-exercise levels within 40 60 minutes (Figure 1), the two are unlikely to be associated with one another. Early research investigating the causes of DOMS (1, 3) suggested that muscle ultrastructure damage and connective tissue damage resulted from eccentric or unaccustomed exercise. This causes calcium to leak out of the sarcoplasmic reticulum and accumulate in the mitochondria, which restricts oxidative phosphorylation (ATP production is stopped). The increased calcium activates enzymes (protease and phospholipase) that lead to myofibril and membrane breakdown. This breakdown of muscle protein results in cell inflammation and in an increase in local muscle temperature due to an accumulation of prostaglandins, histamines, and potassium. As a result, pain receptors (group IV free nerve endings) are activated. All of these events result in the sensation of DOMS (refer to Figure 3). In contrast, Smith (31) suggested that tissue damage alone may not be the best explanation for the cause of DOMS. It was stated that there is a similar sequence of events between DOMS and acute inflammation and that the acute inflammatory response appears to be the mechanism underlying DOMS (refer to Figure 4). This response is caused by increased muscle swelling, increased large white blood cells (macrophages) that assist in the repair of damaged tissue, and increased prostaglandin E2, which sensitizes pain receptors (type III and IV afferent neurons). The primary symptoms of inflammation that occur during DOMS are increased intramuscular pressure, decreased ROM, and pain. Clarkson and Newham (6) suggested that high mechanical tension, muscle strain, and elevated muscle temperature contribute to the development of 8 Strength and Conditioning Journal August 2001

Figure 2. Figure 3. Time course of delayed onset muscle soreness (DOMS) from pre-exercise until 96 hours after eccentric exercise. Note that in Figure 1, blood lactate concentrations return to pre-exercise levels within 40 60 minutes, whereas peak DOMS does not occur until 24 72 hours after exercise. This illustrates that the two do not coincide and that the two are unlikely to be associated with one another. Proposed sequence for the occurrence of DOMS based on muscle ultrastructure damage and the influx of calcium. Adapted from Armstrong et al. (3). DOMS. They observed progressive damage in muscle ultrastructure (Z-line streaming, sarcolemma disruption, and swollen mitochondria) for several days after the eccentric activity. They stated that muscle soreness peaked from 24 48 hours after exercise and that complete recovery and regeneration of muscle fibers takes approximately 3 weeks. Additionally, they reported that inflammation and swelling must be considered major components of DOMS because damaged cells release bradykinin, histamines, prostaglandins, and potassium ions, which activate and sensitize pain receptors surrounding muscle fibers. To date, no research has been able to attribute any one mechanism to the sensation of DOMS or to muscle fiber damage. Current literature suggests that DOMS is not from a single cause but rather from a sequence of events. Generally, the symptoms of DOMS (muscle soreness, decreased ROM, and loss of strength) are associated with damage to muscle ultrastructure, accumulation of calcium, release of intracellular proteins, and inflammation that activates pain receptors. Thus, it is important to understand the biochemical mechanisms behind DOMS in order to make recommendations about ways to avoid and alleviate it. Proposed Methods to Reduce DOMS Use of anti-inflammatory drugs, antioxidant supplementation, cold application, postexercise massage, postexercise stretching, topical ointments and creams, and warm-ups have been studied experimentally (1, 18). Although the results are conflicting, to date, no treatment has consistently reduced DOMS or markers of muscle damage (1, 6, 10, 16, 19). Of all these treatments, warm-up appears to be the most promising way to decrease DOMS. Warm-Up Warming up before an exercise has generally been suggested as a method to prepare the body for exercise, to improve performance, and to reduce DOMS and muscle damage (18, 23, 25 28, 32, 33). Experimental data investigating warm-up before eccentric exercise suggests that it may be a sound approach to minimize DOMS. The physiological results of increasing muscle temperature in- August 2001 Strength and Conditioning Journal 9

fluence the behavior of a muscle. According to Safran et al. (28), proper muscle warm-up can lead to more relaxed muscles; to increased extensibility of the connective tissue within muscle; to decreased muscle viscosity, making contractions smoother; and to increased speed and force of contractions. Collectively, these effects improve muscle function. In 1985, Shellock and Prentice (30) reviewed the effects of warm-up and stretching on physical performance and on prevention of sports-related injuries. They stated that specific warm-up (increasing temperature using the same body parts that will be used in the subsequent, more strenuous activity) is the best approach to improve physical performance because this method provides a rehearsal of the activity or event. Also, they stated that a proper warm-up appears to decrease the incidence and likelihood of sportsrelated musculoskeletal injuries. Recently, Nosaka and Clarkson (23) investigated the effects of performing a fatiguing concentric exercise (100 repetitions of isokinetic concentric contractions of the elbow flexors) immediately before performing eccentric exercise (12 maximal eccentric actions of the elbow flexors). They hypothesized that the concentric exercise would increase DOMS. However, their findings showed that DOMS was decreased after performing the concentric exercise, compared with the case of the eccentric exercise. There was less soreness, faster recovery of maximal isometric force generation, smaller decrease in relaxed elbow joint angle, smaller increase in upperarm circumference, and less creatine kinase activity compared with the case of the eccentric protocol. It was stated that the fatiguing exercise probably served as a warmup and prepared the muscle for the stress of the eccentric exercise. Additionally, Nosaka and Clarkson (23) performed another experiment using a different group of subjects to evaluate the effect of warm-up on eccentric exercise. The subjects moved their elbow joint from an extended to a flexed position by generating minimal force to move the lever arm of the isokinetic device. The velocity of the movement was set at 6.3 rad/s to minimize the load. The subjects were instructed to flex and extend the elbow joint smoothly throughout an entire ROM in 2 seconds. The torque produced during the movements was less than 7 Nm. Then subjects performed 12 eccentric actions of the elbow flexors. The results indicated that warmup exercise before the eccentric exercise also decreased DOMS and muscle damage. There was less soreness, significantly faster recovery of force, a smaller decrease in relaxed elbow joint angle, a smaller increase in upper-arm circumference, and less creatine kinase activity compared with the case of the eccentric condition. There are 3 other studies that have suggested that the symptoms associated with DOMS can be reduced by warm-up. However, these studies used direct muscle temperature measurements to quantify the effect of warm-up on DOMS and/or muscle fiber damage. According to Safran et al. (27), muscle temperature that was increased (isometric contraction lasting 15 seconds) by an average of 1ºC required more force to fail and stretched to greater Figure 4. Proposed sequence for the occurrence of DOMS based on the acute inflammatory response. Adapted from Smith (31). lengths from rest before failing. Warmed muscles also exhibited greater elasticity because less force was generated at given lengths. This evidence suggests that a warm-up will provide benefits in reducing muscle injury (27). Noonan et al. (21) examined the effect of temperature on the mechanical failure properties of rabbit skeletal muscle. For all tests, 1 leg was maintained at 25ºC (cold) and the contralateral leg maintained at 40ºC (warm). Load to failure occurred sooner in the cold muscle for all groups tested. Stiffness was higher in cold muscles for all muscles except one. This would support the theory that warming muscles can aid in injury prevention and improvement in athletic performance (21). 10 Strength and Conditioning Journal August 2001

Finally, an unpublished dissertation by McCluskey (18) investigated the effect of concentric exercise performed immediately before resistive eccentric exercise on DOMS and markers of muscle damage. The warm-up consisted of cycling for 30 minutes at 70 rpm against resistance, eliciting 70% of the age-predicted maximum heart rate. The eccentric exercise protocol consisted of 6 sets of 8 repetitions of eccentric knee extensions, with a resistance of 70% of the 1-RM using the nondominant leg. The results indicated that DOMS was significantly reduced when subjects performed 30 minutes of cycling (warm-up) before resistive eccentric exercise. The average increase in muscle temperature of the treatment groups were elevated by 1.6ºC, and the average increase in core temperature was elevated by 0.5ºC before resistive eccentric exercise. On the basis of the research cited, it appears that a proper warm-up is beneficial before training. However, because each study cited used a different warm-up protocol to evaluate its effect on DOMS and/or muscle damage, the question to be asked is, "What activities should be included in a proper warm-up?" According to McArdle et al. (17), warm-up involves 2 categories, general and specific. General warm-up refers to light calisthenics, running, and nonspecific movements requiring large muscle groups that are not related to the precise neuromuscular actions of the sport. The goal of this type of warm-up is to increase core body temperature. Specific warm-up includes skill applications that are directly related to the sport or activity played (multijoint movements). The desired outcome here is to increase local muscle temperature. Thus, starting with general warm-up and then proceeding to specific warmup exercises is recommended. Proper warm-up may last from 10 25 minutes, depending on the intensity at which it is performed, the athlete's activity, and the environmental conditions. Stewart and Sleivert (33) examined the effect of warm-up intensity on ROM and anaerobic performance. Subjects either did no warm-up or completed a 15- minute running warm-up at 60, 70, or 80% V o 2 max, followed by 3 minutes of lower limb PNF stretching. After 5 minutes of stretching, subjects performed a high-intensity treadmill test (maximal run until exhaustion at 20% grade and 13 km/h velocity). Their results indicated that anaerobic performance significantly improves after warm-up. Therefore, they recommend that a specific warm-up (running at 60 to 70% V o 2 max) be performed for 15 minutes before high-intensity anaerobic activity because in their study, doing so improved ROM and increased time to exhaustion. Finally, when considering strength training, LaChance (15) states that warm-up should entail enough submaximal sets to prepare the neuromuscular system for a limited number of high-intensity sets for selected core exercises involving large muscle groups. Repeated-Bout Effect In addition to warm-up, repeated bouts of eccentric exercise, performed within 1 6 weeks after the initial bout, have been reported in the literature to consistently reduce DOMS and muscle ultrastructure damage (1, 2, 4 7, 9, 11, 16, 19, 20, 22). Further bouts of eccentric exercises will allow faster recovery of strength and ROM and make the muscle more resistant to damage after the first bout (1, 6, 9, 11, 13, 19, 20, 22). If DOMS occurred because of eccentric exercise while weight training, it can be alleviated by further eccentric weight training. If DOMS was sustained during downhill running, additional downhill running or level training can remedy the soreness because both actions use eccentric muscle actions (1, 4, 32). The repeated-bout effect occurs because of the adaptive and protective function against highforce generation being produced among muscle fibers (2, 13, 22). Also, there may be better recruitment of motor units (a motor neuron and all the muscle fibers it innervates) when engaging in the same or similar movements (2, 13, 23). Furthermore, it is thought that during the healing process, muscle and connective tissue are strengthened, making them resistant to further damage (7, 9, 20). This allows the muscle to better withstand the large, potentially damaging forces created by eccentric actions. Recommendations On the basis of the evidence described in this paper, concentric exercise (warm-up) performed before eccentric activity may better prepare the body for the stress caused by the eccentric, damageinducing exercise. Increased muscle temperature results in a reduction in muscle or connective tissue viscosity, a higher resistance of muscle tissue to tearing, and increased muscle elasticity (18, 27, 30). Furthermore, increased blood circulation in muscles or increased muscle temperature may change the environment of the surrounding connective tissue or the sarcolemma surrounding muscle fibers (28). These effects possibly result in the ability of the August 2001 Strength and Conditioning Journal 11

muscle to handle greater loads and therefore in a lower initial mechanical overload due to the eccentric exercise (25). Therefore, to avoid DOMS one should do the following: Perform a general warm-up (jogging, cycling, stairstepper) for 5 minutes. Perform specific dynamic flexibility exercises (butt kicks, carioca, lunges, straight-leg march, leg cradle, drop lunge, lateral lunge, backward-reach run) in a "down-and-back" fashion over 15 yards for 15 20 minutes. When beginning an exercise program, avoid movements that entail strenuous eccentric muscle action (downhill running, plyometrics, heavy downward phase of a weighttraining exercise). Gradually increase intensity and duration for at least 2 weeks by incorporating a modest quantity of eccentric multijoint exercises into the training protocol (32). This pattern of consistent progression allows the exercised muscles to adapt to the exercise stress and therefore reduces the incidence or severity of DOMS (7, 19, 32). References 1. Armstrong, R.B. Mechanics of exercise-induced delayed onset of muscle soreness: A brief review. Med. Sci. Sports Exerc. 16:529 538. 1984. 2. Armstrong, R.B., R.W. Ogilvie, and J.A. Schwane. Eccentric exercise-induced injury to rat skeletal muscle. J. Appl. Physiol. 54:80 93. 1983. 3. Armstrong, R.B., G.L. Warren, and J.A. Warren. Mechanisms of exercise-induced muscle fibre injury. Sports Med. 12:184 207. 1991. 4. Balnave, C.D., and M.W. Thompson. Effects of training on eccentric exercise-induced muscle damage. J. Appl. Physiol. 75:1545 1551. 1993. 5. Byrnes, W.C., P.M. Clarkson, J.S. White, S.S. Hsieh, P.N. Frykman, and R.J. Maughan. Delayed onset muscle soreness following repeated bouts of downhill running. J. Appl. Physiol. 59:710 715. 1985. 6. Clarkson, P.M., and D.J. Newham. Associations between muscle soreness, damage, and fatigue. In: Fatigue: Neural and Muscular Mechanisms. S.C. Gandovia, R. Enoka, A. McComas, D. Stuart, and C. Thomas, eds. New York: Plenum, 1995. pp. 457 469. 7. Clarkson, P., and I. Tremblay. Exercise-induced muscle damage, repair and adaptations in humans. J. Appl. Physiol. 65:1 6. 1988. 8. Colliander, E.B., and P.A. Tesch. Effects of eccentric and concentric muscle actions in resistance training. Acta Physiol. Scand. 140:31 39. 1990. 9. Ebbeling, C.B., and P.M. Clarkson. Muscle adaptation prior to recovery following eccentric exercise. Eur. J. Appl. Physiol. 60:26 31. 1990. 10. Ernst, E. Does post-exercise massage treatment reduce delayed onset muscle soreness? A systematic review. Br. J. Sports Med. 32:212 214. 1998. 11. Eston, R.G., S. Finney, S. Baker, and V. Baltzopoulos. Muscle tenderness and peak torque changes after downhill running following a prior bout of isokinetic eccentric exercise. J. Sports Sci. 14: 291 299. 1996. 12. Fitzgerald, G.K., J.M. Rothstein, T.P. Mayhew, and R.L. Lamb. Exercise-induced muscle soreness after concentric and eccentric isokinetic contractions. Phys. Ther. 71:505 513. 1991. 13. Golden, C.L., and G.A. Dudley. Strength after bouts of eccentric or concentric actions. Med. Sci. Sports Exerc. 24:926 933. 1992. 14. Hough, T. Ergographic studies in muscular soreness. Am. J. Physiol. 7:76 92. 1902. 15. LaChance, P. Rationale for baseline and advanced exercise prescriptions for muscular fitness. Strength Cond. 20(5):45 53. 1998. 16. MacIntyre, D.L., W.D. Reid, and D.C. McKenzie. Delayed muscle soreness: The inflammatory response to muscle injury and its clinical implications. Sports Med. 20:24 40. 1995. 17. McArdle, W., F. Katch, and V. Katch. Exercise Physiology (3rd ed.). Philadelphia, PA: Lea and Febiger, 1991. 18. McCluskey, B.S. The effect of concentric exercise performed immediately before resistive eccentric exercise on delayed-onset muscle soreness and markers of muscle damage. Doctoral dissertation, Auburn University. 1994. 19. Miles, M.P., and P.M. Clarkson. Exercise-induced muscle pain, soreness, and cramps. J. Sports Med. Phys. Fitn. 34:203 216. 1994. 20. Newham, D.J., D.A. Jones, and P.M. Clarkson. Repeated high-force eccentric exercise: Effects on muscle pain and damage. J. Appl. Physiol. 63:1381 1386. 1987. 21. Noonan, T.J., T.M. Best, A.V. 12 Strength and Conditioning Journal August 2001

Seaber, and W.E. Garret, Jr. Thermal effects on skeletal muscle tensile behavior. Am. J. Sports Med. 21:517 522. 1993. 22. Nosaka, K., and P.M. Clarkson. Influence of previous concentric exercise on eccentric exercise-induced muscle damage. J. Sports Sci. 15: 477 483. 1997. 23. Nosaka, K., and P.M. Clarkson. Muscle damage following repeated bouts of high force eccentric exercise. Med. Sci. Sports Exerc. 27:1263 1269. 1995. 24. Powers, S.K., and E.T. Howley. Exercise metabolism. In: Exercise Physiology: Theory and Application to Fitness and Performance (3rd ed.). Dubuque, IA: Brown and Benchmark Publishers, 1997. pp. 45 61. 25. Rodenburg, J.B., H. Thomas, M.A.V. Nieuwenhoven, P. Schiereck, and P.R. Bar. Effects of warm-up, stretching and massage on muscle protein efflux due to eccentric exercise. Med. Sci. Sports Exerc. 25(Suppl.):S158. 1993. 26. Rodenburg, J.B., D. Steenbeek, P. Schiereck, and P.R. Bar. Warm-up, stretching and massage diminish harmful effects of eccentric exercise. Int. J. Sports Med. 15(7): 414 419. 1994. 27. Safran, M.R., W.E. Garrett, A.V. Seaber, R.R. Glisson, and B.M. Ribbeck. The role of warmup in muscular injury prevention. Am. J. Sports Med. 16:123 128. 1988. 28. Safran, M R., A.V. Seaber, and W.E. Garrett. Warm-up and muscular injury prevention. An update. Sports Med. 8:239 249. 1989. 29. Schwane, J.A., B.G. Watrous, S.R. Johnson, and R.B. Armstrong. Is lactic acid related to delayed-onset muscle soreness? Phys. Sportsmed. 11:124 131. 1983. 30. Shellock, F.G., and W.E. Prentice. Warming-up and stretching for improved physical performance and prevention of sports-related injuries. Sports Med. 2:267 278. 1985. 31. Smith, L.L. Acute inflammation: The underlying mechanism in delayed onset muscle soreness? Med. Sci. Sports Exerc. 23:542 551. 1991. 32. Smith, L.L. Causes of delayed onset muscle soreness and the impact on athletic performance: A review. J. Appl. Sport Sci. Res. 6(3):135 141. 1992. 33. Stewart, I.B., and G.G. The New Definitive Source for Strength Training & Conditioning Information The NSCA s second edition of Essentials of Strength Training and Conditioning offers 664 pages of the most current and comprehensive strength training and conditioning information available. Written and edited by some of the world s leading exercise science professionals, this text is a must for strength and conditioning professionals, athletic trainers, physical therapists, educators, sport coaches, personal trainers, other sports medicine specialists and anyone who is preparing for the CSCS examination. Each of the book s 26 chapters provides an overview of an important aspect of strength and conditioning and includes: chapter objectives, key points, application boxes, key terms, study questions as well as questions requiring practical application of key concepts. The second edition includes more than 300 full-color photographs, which are designed to provide a clear visual depiction of proper flexibility, plyometric and resistance training exercise techniques. With the addition of full-color enhancements, this text is destined to become the preferred resource for preparing for the CSCS exam and a valuable addition to the library of the serious professional. B1000 $57.00 M $59.00 NM PLUS SHIPPING AND HANDLING To Order Call 800-815-6826 Sleivert. The effect of warmup intensity on range of motion and anaerobic performance. J. Orthop. Sports Phys. Ther. 27(2):154 161. 1998. 34. Tiidus, P.M., and C.D. Ianuzzo. Effects of intensity and duration of muscular exercise on delayed soreness and serum enzyme activities. Med. Sci. Sports Exerc.15: 461 465. 1983. Szymanski David J. Szymanski, MEd, CSCS, is the exercise physiologist for the Auburn University Baseball Team and a doctoral candidate in the Department of Health and Human Performance at Auburn University. He has a masters degree in Physical Education from Southwest Texas State University and previously was the assistant baseball coach and conditioning coordinator at Texas Lutheran University. August 2001 Strength and Conditioning Journal 13