Effects of varying recovery periods on muscle enzymes, soreness, and performance in baseball pitchers, by Potteiger, Blessing, and Wilson, Journal of Athletic Training, 1992; 27(1): 27–31.
From the Abstract
Results indicate that muscle damage, as evidenced by CK release, occurs in response to baseball pitching. However CK values, muscle soreness, and pitch velocity are not significantly affected by changes in the amount of recovery time typically scheduled between games.
The authors look at a sample of pitchers and how they recover after pitching different lengths of time. The results show a few things. First, the pattern of recovery indicates most healing occurs soon after pitching, and that further recovery occurs at a diminishing rate. After three days of rest, the measures of skeletal muscle damage were back to baseline values. Second, performance on two days of rest is only slightly worse than, and not statistically distinguishable from, performance on four days of rest. This is good news for the Phillies and Roy Oswalt. The results are also consistent with my analysis (with Sean Forman) of major-league pitchers.
You can get the gist of the results from the graphs in the pages below. The study is short, interesting, and it’s not even new. There a lot of studies in the fields of sports medicine, exercise physiology, and sports science that look at popular sabermetric questions. If you have a sabermetric question, it won’t hurt to do a PubMed search on the topic.