Using Recovery Modalities between Training Sessions in Elite Athletes : Does it Help?

Modified muscle use or injury can produce a stereotypic inflammatory response in which neutrophils rapidly invade, followed by macrophages. This inflammatory response coincides with muscle repair, regeneration, and growth, which involve activation and proliferation of satellite cells, followed by their terminal differentiation. Recent investigations have begun to explore the relationship between inflammatory cell functions and skeletal muscle injury and repair by using genetically modified animal models, antibody depletions of specific inflammatory cell populations, or expression profiling of inflamed muscle after injury. These studies have contributed to a complex picture in which inflammatory cells promote both injury and repair, through the combined actions of free radicals, growth factors, and chemokines. In this review, recent discoveries concerning the interactions between skeletal muscle and inflammatory cells are presented. New findings clearly show a role for neutrophils in promoting muscle damage soon after muscle injury or modified use. No direct evidence is yet available to show that neutrophils play a beneficial role in muscle repair or regeneration. Macrophages have also been shown capable of promoting muscle damage in vivo and in vitro through the release of free radicals, although other findings indicate that they may also play a role in muscle repair and regeneration through growth factors and cytokine-mediated signaling. However, this role for macrophages in muscle regeneration is still not definitive; other cells present in muscle can also produce the potentially regenerative factors, and it remains to be proven whether macrophage-derived factors are essential for muscle repair or regeneration in vivo. New evidence also shows that muscle cells can release positive and negative regulators of inflammatory cell invasion, and thereby play an active role in modulating the inflammatory process. In particular, muscle-derived nitric oxide can inhibit inflammatory cell invasion of healthy muscle and protect muscle from lysis by inflammatory cells in vivo and in vitro. On the other hand, muscle-derived cytokines can signal for inflammatory cell invasion, at least in vitro. The immediate challenge for advancing our current understanding of the relationships between muscle and inflammatory cells during muscle injury and repair is to place what has been learned in vitro into the complex and dynamic in vivo environment.

Controversy has surrounded the question about whether high-dose rofecoxib increases or naproxen decreases the risk of serious coronary heart disease. We sought to establish if risk was enhanced with rofecoxib at either high or standard doses compared with remote non-steroidal anti-inflammatory drug (NSAID) use or celecoxib use, because celecoxib was the most common alternative to rofecoxib. We used data from Kaiser Permanente in California to assemble a cohort of all patients age 18-84 years treated with a NSAID between Jan 1, 1999, and Dec 31, 2001, within which we did a nested case-control study. Cases of serious coronary heart disease (acute myocardial infarction and sudden cardiac death) were risk-set matched with four controls for age, sex, and health plan region. Current exposure to cyclo-oxygenase 2 selective and non-selective NSAIDs was compared with remote exposure to any NSAID, and rofecoxib was compared with celecoxib. During 2302029 person-years of follow-up, 8143 cases of serious coronary heart disease occurred, of which 2210 (27.1%) were fatal. Multivariate adjusted odds ratios versus celecoxib were: for rofecoxib (all doses), 1.59 (95% CI 1.10-2.32, p=0.015); for rofecoxib 25 mg/day or less, 1.47 (0.99-2.17, p=0.054); and for rofecoxib greater than 25 mg/day, 3.58 (1.27-10.11, p=0.016). For naproxen versus remote NSAID use the adjusted odds ratio was 1.14 (1.00-1.30, p=0.05). Rofecoxib use increases the risk of serious coronary heart disease compared with celecoxib use. Naproxen use does not protect against serious coronary heart disease.

We examined the effect of two commonly consumed over-the-counter analgesics, ibuprofen and acetaminophen, on muscle protein synthesis and soreness after high-intensity eccentric resistance exercise. Twenty-four males (25 +/- 3 yr, 180 +/- 6 cm, 81 +/- 6 kg, and 17 +/- 8% body fat) were assigned to one of three groups that received either the maximal over-the-counter dose of ibuprofen (IBU; 1,200 mg/day), acetaminophen (ACET; 4,000 mg/day), or a placebo (PLA) after 10-14 sets of 10 eccentric repetitions at 120% of concentric one-repetition maximum with the knee extensors. Postexercise (24 h) skeletal muscle fractional synthesis rate (FSR) was increased 76 +/- 19% (P 0.05) in IBU (35 +/- 21%; 0.021 +/- 0.014%/h) and ACET (22 +/- 23%; 0.010 +/- 0.019%/h). Neither drug had any influence on whole body protein breakdown, as measured by rate of phenylalanine appearance, on serum creatine kinase, or on rating of perceived muscle soreness compared with PLA. These results suggest that over-the-counter doses of both ibuprofen and acetaminophen suppress the protein synthesis response in skeletal muscle after eccentric resistance exercise. Thus these two analgesics may work through a common mechanism to influence protein metabolism in skeletal muscle.