Part 1: DOMS in humans
I thought that this might be a good topic to cover, given that I myself recently suffered from the dreaded effects of DOMS, after completing my longest run in a while. Trail running is one of my passions in life, and I completed my third Two Bays trail run recently. A highlight of the Victorian trail running calendar, 28km of trail traversing the Mornington Peninsula from Dromana to Cape Shank - over three hours negotiating undulating terrain often leads to a few days of hobbling, a severe aversion to stairs and difficulty getting up from chairs! Much to my dismay, physios are no less susceptible to DOMS than anyone else. Post trail run, I spent 10 minutes standing in the bay, cooling my legs in the hope that I would negate some of the nasty DOMS I was expecting to ensue in the coming days. Did it help? Yes, in my experience, I believe it does help. But what does the research say?
First of all, what is DOMS?
DOMS will often occur in humans following unusual or unaccustomed exercise. Clinical signs appear after exercise and tend to peak 24 to 48 hours after the exercise bout, with symptoms lasting up to 5 days.
Although there are many proposed theories as to why DOMS occurs, there is no clear explanation for its incidence. DOMS is more likely to occur after ‘eccentric’ exercise. Eccentric muscle activity is a term which refers to a muscle which is working or activating whilst it is lengthening. In contrast, a muscle which is working whilst it is shortening is known as a ‘concentric’ muscle contraction.
As fewer muscle fibres are working in the eccentrically working muscle, this leads to a higher stress on the soft tissues involved, leading to increased susceptibility to DOMS during this type of muscle activity.
In addition, fast twitch muscle fibres (e.g. the large movement producing muscles of the limbs – notably the quadriceps, hamstring and calf muscle groups) are more vulnerable to the effects of DOMS than slow twitch muscles. The reason for this may be due to selective recruitment of these muscle groups during eccentric exercise or potentially due to some inherent weakness in these muscle groups.
What happens to the muscle?
Research suggests that DOMS is triggered by a variety of inflammatory responses and biochemical changes which occur after muscle damage. This differs from a muscle strain which usually occurs as a result of a single ‘harmful event’ which damages muscles fibres, e.g. overstretching a muscle unexpectedly. Traditionally, DOMS has been attributed with the build-up of lactate in muscle after intense exercise, however, research has shown that this is not entirely the case. The experience of pain which goes hand in hand with DOMS is not solely due to lactate accumulation; although there is a rise in blood and muscle lactate levels during intense exercise, they return to baseline in a shorter time than the typical duration of DOMS symptoms, which increases in the first 24 hours post exercise, and peaks at 24 to 48 hours, after blood lactate levels have returned to a normal level.
The following changes to muscle fibres and connective tissue has been implicated in the development of DOMS:
- Micro trauma to muscle fibres
- Tearing of muscle connective tissue and its tendon insertion: research has shown that higher levels of a specific amino acid called hydroxyproline (which is produced when the body breaks down connective tissue) are found in people suffering from muscle soreness. This suggests that an intense workout may damage connective tissue, increasing the rate of collagen breakdown, creating an imbalance in its metabolism.
- Other research has suggested that specific non-contractile parts of the sarcomere (which is the basic unit of striated muscle tissue) are damaged such as the sarcoplasmic reticulum and connective tissue surrounding muscle proteins (sarcolemma). It appears to be eccentric muscle contractions which damage the sarcomere and lead to muscle cell damage, necrotic muscle fibres and cell death.
- Another theory suggests that high intensity exercise changes the permeability of cell membranes, leading to an increased flow of calcium into the cell, leading to gradual destruction of the sarcolemma and attracting lymphocytes (inflammatory cells) to the damaged area which stimulate nociceptors – specialized parts of the nervous system which alert us to potentially damaging stimuli.
- Although acute inflammation in response to muscle and connective tissue damage caused by eccentric exercise is linked to the development of DOMS (many symptoms of inflammation such as pain, swelling and loss of function, occur due to DOMS), recent research has found that muscle fibre damage is not essential, although it is sufficient, for DOMS to occur.
- Recent evidence shows that DOMS can actually spread (likely due to the influence of the nervous system), to adjacent muscle groups – this is something researchers are currently trying to learn more about.
- DOMS certainly does lead to a decline in physical performance, including reduced muscle strength and flexibility as well as reduced joint range of motion. In addition, a deterioration in proprioception (one’s awareness of body position in space) and coordination is found in those suffering from DOMS. These changes can lead to an increased risk of injury if the athlete does not modify their training or exercise routine whilst recovering from a bout of DOMS.
What is the main difference between DOMS and a muscle strain or tear?
It can be difficult to differentiate between a case of DOMS and mild muscle strain. The main difference is that there is a delay, often up to 24 hours, after exercise, before the onset of DOMS symptoms. Although the signs and symptoms of a mild (grade 1) muscle strain can be similar to DOMS, in the case of a muscle strain, one is more likely to feel symptoms and signs commence during or immediately after the inciting activity.
So what does the research tell us about the optimal treatment of DOMS?
The following is a summary of a selection of relevant research papers, evaluating the effects of commonly used techniques to manage symptoms from DOMS. The results may surprise you!
Cryotherapy (cold therapy)
A systematic review of 36 papers by Hohenauer and others in 2015 found that cryotherapy (cooling and cold water immersion therapy) significantly reduced the symptoms of DOMS experienced by human athletes, with symptoms lasting up to 48 hours, but not having an effect at 96 hours post exhaustive exercise.
A 2011 systematic review in the Cochrane database (Herbert, de Noronha and Kamper) examined the effect that stretching, before or after exercise, had on the development of DOMS and interestingly found that the evidence suggests that muscle stretching before, after, or before & after exercise, does not produce clinically important reductions in DOMS in healthy adult humans.
A 2014 systematic review in the British Journal of Sports Medicine evaluated the effects of compression garments on recovery following intense exercise, with findings indicating compression garments are effective in enhancing recovery from muscle damage.
Self-myofascial release is a popular intervention used to enhance myofascial mobility. Common tools used by athletes include the foam roll and roller massager. Do these tools (note that some people may view them as torture devices!) help reduce the symptoms of DOMS? According to a 2015 study in the International Journal of Sports Physical Therapy (Cheatham and others), use of a foam roller after intense exercise appears to improve joint range of motion (in the short term) and may help maintain muscle performance and reduce DOMS. However, it is worth noting that the use of self -myofascial release before exercise, does not appear to affect muscle performance or recovery.
Interestingly, research by Best et al. (2008) in the Clinical Journal of Sport Medicine found that there is little support for the use of massage to improve function or performance after intense exercise. In contrast, there is good quality evidence available suggesting that massage may facilitate recovery from repetitive muscular contractions – so although sports massage after intense exercise may not improve muscle performance after intense exercise, massage may enhance and speed up recovery as well as reduce the effects of DOMS after intense exercise.
Another study by Ernst, published in the British Journal of Sports Medicine in 1998 concluded that massage therapy may be a promising treatment for DOMS.
O'Connor and Hurley, (2003) looked at the effectiveness of various physiotherapy interventions in the management of DOMS. 30 trials met the inclusion criteria – they found that there was limited high quality evidence suggesting that athletic massage and light concentric exercise are more effective than no treatment, while the evidence for compression therapy, and whirlpool therapy was minimal. Interestingly, they found that there was no evidence supporting the use of static stretching, cryotherapy, acupuncture, pulsed ultrasound, transcutaneous electrical nerve stimulation (TENS), interferential therapy, and microcurrent electrical stimulation in the management of DOMS.
A study evaluating the effect of acupuncture on eccentric exercise-induced DOMS of the biceps muscle has shown that acupuncture does not improve a persons perception of pain or their muscle strength.
Pulsed electromagnetic field (PEMF) therapy
A 2015 study by Hye-Seon Jeon and others evaluated the effect of (PEMF) therapy and sham (placebo) treatment on DOMS-related variables in elbow flexors at 24, 48 and 72 hours after inducing DOMS in 30 healthy male students. The researchers found that the application of PEMF was found to be effective in reducing the symptoms associated with DOMS, including improved recovery of perceived muscle soreness and some measures of muscle contraction, though there was no difference seen between sham treatment and PEMF when looking at muscle power production. The authors concluded that PEMF may be useful to reduce DOMS symptoms, but further research is warranted.
So does DOMS affect animals? Coming up soon in part two, a summary of some interesting research about post exercise muscle soreness in animals, and what we can do to help.