The Relationship of Isometric Strength and Endurance as Fatigue Develops.
Interim scientific rept.,
SAINT LOUIS UNIV MO DEPT OF PHYSIOLOGY
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Results have been obtained on the development of isometric fatigue in muscle after fatiguing and non-fatiguing bouts of isometric exercise in male human subjects. Change in maximum voluntary contraction MVC under these conditions showed that during isometric contraction at 5-10 percent of MVC and at 25 to 70 percent MVC, there was a linear fall in strength throughout the isometric effort. This was particularly surprising at 5-10 percent MVC since these levels are considered to be non-fatiguing. Endurance was reduced at 25 to 40 percent MVC by performing exercises previously at any tension. When two contractions at 40 percent MVC were performed with an interval of 10 mins between them, the duration of the second contraction was always about 80 percent of that of the first. However, if a contraction of 10 percent MVC was maintained during the 10 min interval between the two fatiguing contractions at 40 percent MVC, the duration of the second contraction was reduced to 28 percent of the first.
- Stress Physiology