Delayed-onset muscle soreness (DOMS) after exercise can be significantly reduced by wrapping a fabric with electromagnetic shielding properties around the relevant exercising muscles. So found a group of Canadian researchers, who experimented with a fabric made of stainless steel and nylon thread, which has proved effective in controlling phantom limb pain and may also relieve rheumatic pain.

The researchers, from the University of British Columbia in Vancouver, worked on the hypothesis that the fabric, called Farabloc, would reduce the inflammatory response to exercise-induced muscle damage, so causing less pain and strength loss. They speculated that the use of Farabloc would alter the balance of frequencies of electromagnetic fields to which the DOMS-afflicted muscle cells would be exposed, permitting continued exposure to low-frequency electromagnetic fields but effectively blocking high-frequency fields, thereby suppressing an inflammatory response and the formation of highly-reactive chemicals known as free radicals.

Twenty untrained volunteers (10 men and 10 women) were divided into two groups that were treated alternately as the experimental group (ie using Farabloc) and the control group (using an identical-looking but inactive fabric). All the participants induced DOMS in their right quadriceps muscles by performing 20 sets of 10 repetitions of knee extension work lasting just under 37 minutes. Those in the experimental group then had their right thighs wrapped in a double layer of Farabloc for five days, while the controls used the placebo fabric.

Muscle soreness and strength were assessed daily for five days, and blood samples were taken five times in the first 48 hours to calculate levels of various blood markers of muscle damage. The results were conclusive: participants using Farabloc experienced significantly less pain and loss of strength compared with the placebo group. They also had significantly lower blood levels of all the markers of muscle damage: malondialdehyde, an indicator of free radical formation; creatine phosphokinase and myoglobin, markers of an inflammatory response; and leukocytes and neutrophils, white blood cells which also indicate an inflammatory response.

'Double layers of Farabloc fabric wrapped around the thigh of human subjects after eccentric exercise demonstrated attenuation of the symptoms, signs and muscle inhibition associated with DOMS,' the researchers report in the Clinical Journal of Sport Medicine. 'The magnitude of this effect suggests a substantial clinical reduction of postexercise disability with this model of muscle injury.'

They are unable to explain how the body's response to muscle activity is altered by use of the fabric, although the blood tests suggest it works by limiting the formation of free radicals and muting the normal inflammatory response to exercise. They conclude that further study of the effects of Farabloc are essential because the principles could be applied to a wide variety of clinical conditions apart from DOMS.

Clin J Sport Med 2000 Jan; 10 (1): 15-21

...and how DOMS responds to a second bout of exercise
If you bring on a bad case of DOMS with a heavy exercise session, will a repeat session make things worse? Not according to an Australian research team, which found that a second bout of maximal resistance exercise performed during the early recovery period from an initial bout neither aggravates the initial damage nor retards the recovery process.

wenty non-resistance trained subjects (10 men and 10 women) were randomly assigned to an experimental group or a control group. Both groups performed an initial bout of 36 maximal isokinetic eccentric contractions of the elbow flexors of their non-dominant arm, then the experimental group repeated the session two days later. Total work and peak eccentric torque were recorded during each set of exercises. Isometric torque, DOMS, flexed elbow angle and plasma creatine kinase (CK) activity were measured before and immediately after each bout, then at 24-hour intervals for seven days and again on day 11. Key results were as follows:

* During the first bout of exercise, there were no significant differences in the total work values of the experimental and control group, with mean values falling gradually over the six-set protocol. In contrast, total values generated by the experimental group during the second bout were significantly lower and remained unchanged through the six sets;

* Peak eccentric torque values followed the same pattern;

* In terms of isometric torque, both groups experienced a 50% reduction immediately after the first bout, with no recovery over the next 48 hours. Despite the fact that the experimental group then incurred a further 30% post-exercise impairment in torque production immediately after the second bout, there were no significant differences between the two groups for the remainder of the study;

* Changes in flexed elbow angle followed a similar pattern, with no significant differences between the groups from day three onwards;

* Muscle soreness in both groups peaked between 48 and 72 hours after the first exercise bout, with no evidence of additional soreness in the experimental group following the second bout;

* Plasma CK, an enzyme involved in metabolic breakdown of creatine, was significantly elevated in both groups right up to day 11, but no further increase was induced by the second bout of exercise.

The most unexpected finding of this study was the lack of change in strength variables throughout the six sets of the second exercise bout, in contrast to the first bout, when participants experienced a gradual fall-off in strength. The researchers speculate that the first exercise bout may have caused selective damage to Type 11 (Fast twitch) muscle fibres, leading to a reliance during the second bout on Type 1 fibres, which are slower to fatigue, yet weaker. But the overall message is that, however much you hate the thought of exercise when you are suffering with DOMS, you can't actually make things worse by pushing yourself.

J Sci Med Sport 2000 Mar 3 (1) 35-43

Isabel Walker