The relationship between muscle hardness and the muscle tenderness threshold in muscle fatigue: In the case of ski instructors during a ski training camp

Abstract

[Aims] The purpose of this study was to examine the relationship between muscle hardness and muscle tenderness threshold in ski instructors during a ski training camp. [Methods] Five ski instructors (ranged 21 to 60 years) participated in this study. All subjects voluntarily gave written informed consent to participate in this study. The research was held from Dec.24 to 28, 2015 in Niseko Annupuri International Ski Area. We measured the muscle hardness and the muscle tenderness threshold in muscles (trapezius muscle and tibialis anterior muscle in both dominant and non-dominant sides) every morning of each day. The skiing distance, instructing time and air temperature were also measured during the ski training. [Results] There was no change in muscle hardness of the trapezius muscles during ski training. However, the muscle hardness of tibialis anterior muscles and muscle tenderness threshold of two muscles were significantly enhanced (p<0.05–p<0.01) day by day. Between muscle hardness and muscle tenderness threshold in each muscle of individual subject, there were the correlation (trapezius muscle: r=0.54–0.83, tibialis anterior muscle: r=0.21–0.8, (n=5)). Each one subject in two muscles was showed a significant correlation, in contrast, other subjects were not showed. [Conclusions] There were no related between muscle tenderness threshold and muscle hardness, when muscle fatigue of ski instructors enhanced during ski training. Our results suggested that the change of muscle tenderness threshold was no affected by the change of muscle hardness within physiological variation in increasing muscle fatigue. And, the change of muscle tenderness threshold may be affected by the several other factors, for example the mental stress.