Running performance and running related injuries are important topics in long-distance running competitions, and the mechanical stresses that occur in body tissues during running are important factor for both. Previous studies have shown that gait retraining have the potential to appropriately modify the characteristics of variables that reflect mechanical stress, such as negative work and maximal moment of the knee and ankle joints during the stance phase. However, the relationship between the variables available for gait retraining and the mechanical variables has not been adequately demonstrated, and there is insufficient information on how the mechanical variables change with changes in the intervening variables. Therefore, in this study, ground contact time （GCT）, backward foot velocity before touchdown （BFV）, and stride frequency （SF）were selected as variables that could potentially be used for gait retraining, and the relationships between these variables and negative work （KNW, ANW）and maximum moments （PKM, PPFM）of the knee and ankle joints during the stance phase were investigated in 31 runners with various running performances （10 km equivalent time: Max 29’18”-Min 37’17”）, running at 3.0 m/s. Pearson’s product correlation analysis revealed significant （ p < 0.05）positive or negative correlations between GCT and PPFM, ANW, and KNW （r = -0.89, -0.77, 0.57, respectively）, as well as BFV and PPFM, ANW, and KNW （r = 0.73, 0.65, -0.53）. For SF, a significant （ p < 0.05）negative correlation （r = -0.66）was found with KNW. These findings suggest that GCT, BFV, and SF are useful for use in gait retraining. In addition, a significant （ p < 0.05）negative correlation （r = -0.54）between GCT and SF was also found, while no significant correlation （r = 0.23）was found between BFV and SF, suggesting that BFV can be used as a variable to change PPFM, ANW and KNW without changing SF.

Dr. Y. Kuno summarized the results of extensive research on the human thermoregulatory effector system, heat stroke, and heat illness, and published the “Story about sweat” （1963）. To date, this book has been known as the bible for young investigators of the prevention of heat illness. However, today, some of the contents is inaccurate. In this article, we will introduce the “Story about sweat” （1968, 5 ^th edition） to compare/confirm new findings. As examples, 5 items are presented: 1. Exertional heat illness, including exercise-related heat illness, was defined as a state in which there is a >5℃ gap between skin and core temperatures in addition to a rectal temperature of >40℃. 2. In a hot environment, the most important function for thermoregulation during work or sports activities is heat loss by sweat secretion from sweat glands and its evaporation. 3. Sweating arrest is a danger signal of heat illness. 4. A desire for water is perceived as a sense of thirst. 5. An adequate criterion for the prevention of heat illness is whether the rate of weight loss is maintained at <2 to 3%. However, the rate of weight loss immediately after a race in a hot environment sometimes increases to 5 to 11% in elite marathon runners. This suggests an improvement in heat acclimation during routine training in elite runners.