Analysis of urinary hydroxyproline levels and delayed muscle soreness resulting from high and low intensity step testing under gelatin- free and gelatin-loading dietary regimens

Abstract

This study investigated the connective tissue damage theory of delayed muscle soreness and determined if changes in dietary intake of gelatin would affect the intensity of exercise-induced soreness. 20 subjects (16 males, 4 females ) underwent 2, 4-day sessions of step testing. The first session involved high intensity bench stepping to induce delayed soreness. The second session was low intensity, so as to not promote soreness, but of vertical displacement workload equivalent to the first. Daily urinary excretions were recorded and the first void of each morning was collected for analysis. Ratings of perceived soreness (PS) in the working muscles were noted each day. Gelatin-free or gelatin-load dietary regimens were imposed for each 4 day session. Alterations in hydroxyproline excretion per 24 hrs (OHP) were evaluated to show changes in collagen metabolism and connective tissue degradation. The ratio of 24 hr excretion of hydroxyproline to 24 hr excretion of creatinine (0HP/cr) was used to correct for differences in body size. No statistical differences (p>.05) in PS were found between the gelatin-free and gelatin-load subject groups. Sig diffs in OHP (P<.01) and OHP/Cr (P<005) were evident between the gelatln groups, indicating that gelatin loading resulted in increased hyrdroxyproline excretion. Although there was an increase in DHP and OHP/Cr during the high intensity stepping, but not during the low intensity stepping, this difference was not statistically significant (p>.057. Dietary gelatin alterations had no effect on the severity of delayed muscle soreness. While delayed soreness appeared to be associated with connective tissue damage, sig diffs in hydroxyproline excretion were not evident to support this postulate.