Walking Race Research Articles

50-mile walking race suppresses neutrophil bactericidal function by inducing increases in cortisol and ketone bodies

To examine the effect of intensive aerobic exercise on the interaction between endocrine and immune systems, we studied in ten normal healthy male subjects the effect of a 50-mile walking race on blood concentration of hormones (insulin, GH, ACTH, cortisol, adrenaline, noradrenaline, and dopamine), ketone bodies, specific immunological functions (IgG, IgM, and PHA/Con A-induced lymphocyte blastformation test), and nonspecific immune (CH 50, and neutrophil bactericidal functions). Neutrophil bactericidal activity was measured as chemiluminescences amplified by luciferin analog (CLA-DCL) and luminol (L-DCL). The race increased cortisol and ketone bodies, and decreased insulin, CLA-DCL, and L-DCL (all parameters; P < 0.01). However, other parameters were not significantly changed. There were significant negative correlations between changes of ketone bodies/cortisol and CLA/L-DCL (P < 0.05), however there was no significant correlations between changes of insulin and CLA/L-DCL. These data indicate that extensive aerobic exercise causes impaired neutrophil bactericidal function, probably due to the induced increases in both cortisol and ketone bodies. This impaired neutrophil function may cause the susceptibility to infection after an extensive exercise.

Serial water changes in human skeletal muscles on exercise studied with proton magnetic resonance spectroscopy and imaging.

In vivo 1H-magnetic resonance imaging (MRI) enabled us to study the distribution of water in living tissues and to document changes in human skeletal muscles during physical exercise. The purpose of the present study was to determine the total muscle water changes after exercise using water in 1H-MR spectroscopy and to compare these changes to the signal intensity change on T2*-weighted images and/or to the T2 value change. Seven young male volunteers were positioned in a 1.5 T Philips MR imaging system. They were then asked to dorsiflex their ankle joint against a 2 kg weight once every 2 seconds for 2 minutes. The peak height of water declined according to the clearance curve after exercise in all seven cases with the 1H-MRS similar to the signal intensity. The increasing rate at peak height of total muscle water exceeded both the signal intensity and the T2 value because the water peak height on the 1H-MRS included the extracellular water. In addition, we measured the changes in signal intensity in both calf muscles after walking race exercise. The time intensity curves were used to draw a clearance curve for each muscle group after exercise. It was possible to discern which muscle was used most from the T2*-weighted image that was obtained once after exercise.