Research Review Part One (Reviews 1-5) by (Dr) Paul Batman
Up Front
Many beginning clients complain of the acute muscle soreness that sometimes accompanies exercise participation. In some cases it can be so severe as to discourage them from continuing with their exercise program. The pain associated with exercise is referred to as “Delayed Onset Muscle Soreness” or DOMS. Psychologists have termed this initial exercise period as the “Initial Discomfort Stage”. As participation continues, the Delayed Onset Muscle Soreness becomes less acute, with the client adjusting to the exercise demands. The fitness instructor should be aware of the implication of DOMS and structure fitness activities according to how their clients adapt to these changes. Delayed onset of muscle soreness peaks at 48 hours post exercise and appears to be affected more by eccentric exercise. The characteristics of DOMS are varied and debatable, as are the causes. This research review examines the causes of DOMS and the many symptoms of muscle damage.
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(Dr) Paul Batman
Research Review 1
Acute Inflammation: The Underlying Mechanism in Delayed Onset Muscle Soreness Smith, L.L. (1991)
Medicine and Science in Sports and Exercise. 23 (5). 542-551.
Introduction
A common phenomenon experienced by many clients, is the delayed onset of muscle soreness (DOMS) following unaccustomed exercise. The muscle soreness is usually felt from one to three days following the exercise, which typically has a significant eccentric component to it. The muscle soreness is associated with a loss of function.
Unaccustomed eccentric exercise can cause disruption of both contractile tissue and connective tissue within the muscle. What has not been well established is the mechanism underlying DOMS. There is considerable evidence that DOMS is due to acute inflammation. However, this has not been universally accepted as the mechanism.
Acute Inflammation
Acute inflammation is the body’s healing response to any form of tissue injury. Inflammation involves a biphasic vascular response, with an initial vasoconstriction period followed several hours later by vasodilation and increased vascular permeability. Inflammation also involves a cellular response, with both neutrophils and monocytes (white blood cells) concentrating at the injured tissue site. Their function is to remove dead or necrotic tissue and foreign bodies and to promote the healing process.
No Association between Acute Inflammation and DOMS
A number of studies examining DOMS reported no sign of neutrophils or macrophages following bouts of eccentric exercise. Other studies have used anti-inflammatory drugs following eccentric exercise to control the impact of DOMS. However, DOMS was still experienced, suggesting that muscle soreness was not attributed to inflammation, but rather to some other mechanism.
Links between Acute Inflammation and DOMS
Signs and symptoms associated with acute inflammation that are linked to DOMS include:
Pain is an important symptom associated with inflammation. Pain receptors, sensitised by prostaglandins of the E series (PGE) are activated by previously benign chemical, mechanical and thermal stimuli.
Several studies have shown an increase in PGE coinciding with the onset of DOMS. It is thought that macrophages (white blood cells), present in large numbers at the injury site 24 to 48 hours after unaccustomed eccentric exercise and are responsible for producing the PGE.
Swelling is always present in acute inflammation. Increased permeability of small blood vessels allows protein-rich fluid to move into the affected tissue. Several studies have reported increased swelling 24 to 48 hours after unaccustomed eccentric exercise, coinciding with the presence of DOMS.
Loss of function occurs as a result of inflammation. The loss of functionor the inability to generate force is thought to be due to mechanical interference by the swelling and/or a reflex inhibition of the affected muscles. Following unaccustomed eccentric exercise, loss of function has been reported from immediately after exercise to 14 days after exercise.
This phenomenon has not been observed following isometric or concentric exercise. The reduced force generation appears not to be related to DOMS. It is thought that the pain associated with DOMS is to encourage immobilisation during a critical period of tissue healing.
Heat and redness are both associated with acute inflammation and are due to increased blood flow through the affected tissue. While heat and redness are not typically found on the skin surface where DOMS is felt, this could be due to the damaged tissue being deep within the muscle or in a deeply located muscle.
Proposed Sequence of Events Associated with DOMS
1. Tissue disruption follows unaccustomed eccentric exercise.
2. There is a significant elevation in circulating neutrophils, which migrate to the affected area.
3. This is followed by the arrival of a large numbers of monocytes (macrophages) to the affected area (24 to 48 hours after exercise).
4. Macrophages produce PGE, which sensitises pain receptors. While DOMS is not felt at rest, exercise or touch increases intramuscular pressure, mechanically stimulating sensitised pain receptors.
Application for the Fitness Instructor
1. Pain, swelling and loss of function are elements that are associated with inflammation that also occur with DOMS.
2. DOMS is most prominent 24 to 48 hours after unaccustomed eccentric exercise. Associated with DOMS is a large increase in macrophages, fibroblasts and lysosomal activity.
3. Signs of healing tend to occur at approximately 72 hours, however this time line and the severity of DOMS depends on the amount of tissue damage, which is influenced by the form of eccentric exercise, intensity and duration of exercise and the level of training of the subject.
Research Review 2
Hyperbaric Oxygen Therapy does not Affect Recovery from Delayed Onset Muscle Soreness.
Mekjavic, I.B., Exner, J.A., Tesch, P.A. & Eiken, O. (1999)
Medicine and Science in Sports and Exercise. 32 (3). 558-563.
Introduction
Delayed onset muscle soreness (DOMS) can result from acute bouts of
high-force eccentric exercise. This exercise stimulus results in muscle damage as reflected by raised levels of circulating muscle proteins, muscle stiffness, reduced force production, and edema. Suggested treatments for DOMS include anti-inflammatory drugs, massage and light exercise.
Hyperbaric oxygen therapy (HBOT) has been used reportedly successful in treating a variety of muscle injuries.
The purpose of this study was to examine the effects of HBOT on the recovery of muscle strength, muscle soreness and edema in subjects following a bout of high-force eccentric exercise.
Method
Subjects for this study were 24 healthy young males. The group was divided into an experimental group and a placebo group. The subjects were tested for right arm maximal isometric forearm flexion strength over 3 trials. The subjects were re-tested 10 minutes after the eccentric exercise and once daily for the next 10 days. The subjects also gave a subjective rating of muscle soreness each day and arm girth was measured daily for indications of edema.
After the initial strength test, the subjects performed 6 sets of 12 maximal effort eccentric forearm contractions involving the biceps brachii and brachialis muscles.
Each day for 7 days, the experimental group breathed 100% oxygen in a hyperbaric chamber. The placebo group breathed air of normal oxygen content in the same chamber. Transcutaneous oxygen content (TcPO2) was measured in each subject’s arm on one occasion while in the chamber. This was completed by placing an electrode on the skin over the biceps muscle.
Results
Each group experienced similar reductions in strength over the 10 days post-exercise. Muscle strength recovery was similar for each group. There was no difference in perceived muscle soreness or arm girth between the two groups. In this experiment, hyperbaric oxygen therapy was not an effective treatment for DOMS.
Application for the Fitness Instructor
1. Whereas hyperbaric oxygen therapy may be a useful mode of treatment for some soft tissue injuries, it does not appear to be an effective treatment for delayed onset of muscle soreness. It does not significantly reduce the soreness or assist in the recovery of lost strength as a result of high-force eccentric exercise.
2. Other treatments such as gentle massage and rest may the best way to manage DOMS. The best plan is to avoid exercise sessions that
result in moderate to severe DOMS. That is, ensure that muscles are well conditioned before subjecting clients to eccentric exercise and then gradually incorporate this form of exercise into their strength program.
Research Review 3
Muscle Damage Induced by Stretch Shortening Cycle Exercise.
Kyrolainen, H., Takala, T. & Komi. P. (1998)
Medicine and Science in Sports and Exercise. 30 (3) : 415-420.
Introduction
It is well known that muscle soreness or damage can result from exercise participation. Indicators of muscle damage have included elevated creatine kinase (CK) levels. Creatine kinase is perhaps the most widely measured protein after intense exercise. It indicates there has possibly been a rupture of the muscle cell membrane, as it is found almost exclusively in the muscle.
Other proteins measured include carbonic anhydrase found mostly in slow twitch fibres and myoglobin found in both fibres. These protein levels are affected by fibre distribution, type and intensity of exercise and the training age of the client.
The purpose of this study was to investigate changes in proteins following a series of repetitive and strenuous stretch shortening cycle exercises performed by endurance and power athletes.
Methods
Eleven power trained athletes and 10 endurance trained athletes volunteered for this study. Subjects were tested with drop jumps and a sledge apparatus. Blood samples were tested for creatine kinase, carbonic anhydrase and myoglobin at the completion and two hours post exercise.
Results
Subjects in both the power and endurance groups increased in all protein levels immediately after the exercise. Protein levels in the endurance group increased in the two hours following exercise. This was not the case in the power group.
Application for the Fitness Instructor
- There was an increase in creatine kinase, carbonic anhydrase and myoglobin in both the endurance and power groups immediately following exercise. The endurance group continued to increase all protein levels in the two hours following the exercise. This indicated that the higher the oxygen uptake, the higher the protein levels.
- The increased creatine kinase activity following exercise indicated that there was some disruption of the muscle cell membrane following the exercise. Again this was greater in the endurance group in the two hours following exercise.
- The difference in muscle damage between the endurance and power groups is difficult to explain. It is perhaps best explained by the difference in fibre distribution between both groups. Creatine kinase and myoglobin may be leaked from type 1 fibres for an extended period of time (two hours). In the power exercise there appeared a more efficient recruitment of muscle fibres.
Research Review 4
Anti-inflammatory Treatment of Muscle Injuries in Sport Almekinders, L.C. (1999).
Sports Medicine. 28 (6). 383-388
Introduction
Muscle injuries in sports include partial or complete tears, contusions
(bruises) and damage due to eccentric exercise resulting in delayed onset of muscle soreness (DOMS). Muscle injuries ranging from moderate to severe can prevent participation for several weeks and even then weakness, inflexibility and re-injury can pose problems. A mode of treatment for these injuries has been the use of anti-inflammatory drugs and other modalities aimed at treating inflammation.
Pathology of Muscle Injuries
An acute muscle tear / strain or contusion results in the rupture of muscle and connective tissue. Muscle cell death occurs and signs of haematoma are obvious. Intense inflammation follows over two or three days, with macrophages clearing out dead tissue. Muscle regeneration and scar tissue formation is apparent one week after the time of injury. It is thought that smaller and fewer muscle fibres are the final result of the healing process plus additional connective tissue.
DOMS results in focal damage within fibres, rather than cell destruction. There is an inflammatory response, but this does not coincide with the symptoms of DOMS. Regeneration results in fully restored muscle fibres with no additional connective tissue.
Stretched-Induced Muscle Injuries
These are most common in muscles which cross two joints, such as the hamstrings. Tears tend to occur at the muscle-tendon junction and are followed by an intense inflammatory response, which is accompanied by pain and disability. It is debatable whether the inflammatory response should be reduced, as this would delay the clearing away of cell debris and necrotic muscle fibres. This phagocytic function (cell eating) is necessary for the healing process and tissue regeneration. To reduce inflammation, non-steroidal anti-inflammatory drugs (NSAIDs), as well as physical modalities have been used.
Non-steroidal Anti-inflammatory Drugs (NSAIDs)
NSTAIDs have been found to delay and possibly reduce the inflammatory response to injury. They also appear to slow the regeneration process. One study reported more pain seven days after injury when using NSTAIDs. If used at all, it is recommended that it be used soon after injury and stopped when inflammation peaks.
Physical Modalities
The traditional treatment for strain injuries has been rest, ice,
compression and elevation (RICE), to be later followed by stretching and strengthening. Studies have yet to confirm whether this is an effective approach to the treatment of acute strain injuries.
Muscle Contusion
In the treatment of muscle contusion injuries, there is no evidence for or against the use of NSAIDs. Animal studies have shown some positive and negative effects. Experimental use of anti-inflammatory steroids such as hydrocortisone have shown some early muscle sparing effects, but also appear to have retarded the healing and muscle regeneration process.
At the moment, it would appear that corticosteroids do not have a place in the treatment of contusions. Some recent studies have found positive effects in the use of anabolic steroids, with more rapid healing and restoration of force generating capacity. There has been little study into the use of physical modalities in the treatment of contusions. One study showed no benefits in the use of compression for the treatment of muscle contusion. Similarly, hyperbaric oxygenation showed no beneficial effects.
The use of strengthening and stretching would seem logical in the treatment of such injuries, in order to restore lost strength as a result of disuse, and regain lost flexibility due to scar tissue formation.
Delayed Onset of Muscle Soreness (DOMS)
DOMS, resulting from eccentric exercise, usually peaks about 48 hours after exercise. Anti-inflammatory drugs have been used in an attempt to reduce the symptoms. NSAIDs have been used in several studies for the treatment of DOMS and results have been conflicting. It has generally been concluded that these drugs have no significant beneficial effect in the treatment of DOMS, the symptoms of which appear to be due to mechanical damage rather than inflammation. Massage therapy and other modalities have produced conflicting results in the treatment of the symptoms of DOMS. Some studies have shown benefits from massage, other studies have not. Other modalities such as ultra-sound, electrical stimulation and intermittent pneumatic compression have not shown significant beneficial effects.
Application for the Fitness Instructor
1. It would appear that the early benefits of anti-inflammatory drugs (reduced inflammation) on muscle injuries, are outweighed by the later negative effects (delayed removal of debris and delayed regenerative process). Perhaps their use should be limited to the very early period only, to allow the healing process to proceed normally.
2. Anabolic steroids research looks promising, but their use raises ethical problems for athletes. Their use for medical purposes would have to be cleared by a particular sport’s governing body.
3. Until research can come up with more effective treatment procedures for muscle injuries, RICE followed by massage, strengthening and stretching seem to be the way to go, with a conservative return to sport activities.
Research Review 5
Structural and Mechanical Basis of Exercise-Induced Muscle Injury. Friden, J. & Lieber, R.L. (1992)
Medicine and Science in Sports and Exercise. 24 (5). 521-530
Introduction
Any form of vigorous or prolonged exercise disturbs the muscle cells
homeostasis. Eccentric exercise has the most damaging effect on the muscle’s sarcolemma, internal structure and extracellular connective tissue. The Z-band or disk is considered to be an integral component of the cell’s cytoskeleton. Its structure is not well understood but is closely linked to the actin filaments and possibly to the myosin filaments.
Myofibrillar Disruption following Eccentric Contractions
Such disruptions include mal-alignment of the Z-bands between adjacent myofibrils, total disruption at the level of the Z-bands, total disruption of the A-bands (myosin filaments) and extensive disruptions of whole sarcomeres with a disappearance of the striated pattern.
Cytoskeletal Reactions
In order to maintain the structural integrity of the sarcomeres and adjacent myofibrils, intermediate filament bridges link adjacent myofibrils at the Z-bands or disks. These intermediate filament bridges help maintain myofibrillar alignment during muscle contraction. Also identified are intermediate filaments attached longitudinally to the periphery of the Z-bands. These peripheral longitudinal intermediate filaments could help prevent overstretching of the sarcomeres. These filaments, composed of the protein desmin, could play a role in the repair of damaged sarcomeres and the formation of new sarcomeres (sarcomerogenesis). Evidence of this has been shown in the laboratory using human vastus lateralis biopsies taken hree days after eccentric exercise. There was also evidence of lysomal degradation, due possibly to the release of hydrolytic enzymes, further degrading contractile and cytoskeletal elements.
Time Course of Myofibrillar Changes
Myofibrillar damage increases from immediately after exercise, up to three days post-exercise. One study showed focal disturbances to the bands of fibre striations to increase from 32% of fibres one hour post-exercise, to 52% after three days, reducing to 12% by day six. The reason for this increase in fibre damage is thought to be due to excess Calcium ions in the cytoplasm, which activate proteolytic (protein destroying) enzyme activity.
Mechanical Imbalance between Adjacent Sarcomeres
When a muscle fibre is contracting concentrically, the differences in forces generated by adjacent sarcomeres varies by only 1-2% of max. When the fibre is performing eccentric contractions, the differences in forces generated by adjacent sarcomeres may vary by more than 50% of max. This variation in forces puts undue directional stress on the Z-disks leading to fibre damage.
It would appear that the damage is due to the imbalance in forces rather that the absolute tension developed. Often high forces are developed in passive stretching of muscles without fibre damage.
Fibre Type and Specificity and the Mechanism of Damage
Human studies have shown that following eccentric exercise, three times as many fast twitch (FT) fibres were damaged compared to slow twitch (ST) fibres. ST fibres have broader more robust Z-disks than FT fibres allowing them to withstand high stress levels. The FT fibres that sustained most damage were the fast glycolytic (FG) or type 11B fibres and not the fast oxidative glycolytic or type 11A fibres. It would appear that the oxidative capacity of the fibres is an important factor in eccentric exercise muscle damage.
Apparently, a period of endurance training prior to eccentric exercise training, greatly lessens the muscle damage from eccentric training. Endurance training would cause some conversion of type 11 B, types 11A fibres as well as enhance the oxidative capacity of the remaining type 11B fibres. Type 11B fibres would be the first to fatigue as exercise continues. Their reduced ability to generate ATP would cause it to stiffen and be more resistive to the lengthening process, leading to mechanical disruption.
Application for the Fitness Instructor
1. Before introducing clients to an eccentric exercise program, the clients should be given an aerobically based exercise program to increase the oxidative capacity of the fast twitch fibres, specifically the type 11B fibres, as well as allowing time for the conversion of some type 11B fibres to type 11A fibres. This would lessen the muscle damage and DOMS associated with eccentric exercise.
2. When clients experience early symptoms of DOMS, this is an indication of muscle damage and hence exercise should be avoided until the symptoms of DOMS are gone. Exercise at this time could increase the extent of the muscle damage and prolong the period over which DOMS is experienced.
Follow (Dr) Paul Batman in these reviews which will complete with a ‘bottom line’ summary and a small ‘test yourself quiz’. If you are interested in learning more about DOMS consider taking one of our more advanced level Diploma courses such as Personal Training, Pilates, Sports Massage or Yoga. All of which include modules on muscle development, kinetic chain dysfunction and movement correction.
(Dr) Paul Batman
Is an international lecturer in Exercise & Sports Science degree and M.Sc programmes. With Andrew Richardson he started the Fitness Institute of Australia specializing in training fitness professionals. He is currently consulting for educational institutions in curriculum design and writing educational materials. His work is world famous and his ability to analyse deep scientific principles and bring them alive in simple application is second to none. Join us for a series of writings by Paul. If you have an area of interest and would like his view please do let us know.