All serious athletes are familiar with delayed onset muscle soreness (DOMS). Delayed onset muscle soreness, which generally strikes 24 to 48 hours after a challenging workout, usually features painful, tender, swollen muscles, and - most distressingly - a reduced ability to train. Naturally, exercise scientists have looked for ways to reduce the severity of delayed onset muscle soreness - and shorten the duration of its symptoms.
Although oral analgesics are commonly prescribed for delayed onset muscle soreness, there has been a lack of data concerning the actual effects of these painkillers. In an effort to remedy that situation, researchers recently induced delayed onset muscle soreness in the non-dominant elbow flexors (biceps muscles) of 60 healthy volunteers (30 men and 30 women; too bad researchers didn't have this level of numbers in the BCAA study noted above). 12 subjects were randomly allocated to one of five groups: (i) placebo, (ii) aspirin (900 mg), (iii) codeine (60 mg), (iv) paracetamol (1000 mg), (v) control. The drugs and placebo were given daily for a total period of 11 days after the delayed onset muscle soreness-inducing exercise was carried out ('Managing delayed onset muscle soreness: lack of effect of selected oral systemic analgesics,' Arch Phys Med Rehabil vol. 81 (7), pp. 966-972, 2000).
Despite the wide range of analgesics used in this study, researchers found no evidence of effectiveness of any of the treatments (outcome measures included pain, mechanical pain threshold, and range of extension and flexion around the elbow joint). Thus, in this well-conducted, placebo-controlled, prospective, double-blind study, there was absolutely no benefit associated with utilising paracetamol, codeine, or aspirin to treat muscle soreness (at least in the doses used in the research). When it comes to delayed onset muscle soreness, muscles seem 'to have a mind of their own,' and it is difficult to get them to protest less vehemently or regain their flexibility and strength more quickly by using analgesics. It's better to limit delayed onset muscle soreness in the first place by using sensible training progressions which feature few large jumps in volume and intensity.