Nature of perceived effort and fatigue

Male Ss maintained handgrip contractions at constant perceived effort for 120-150 sec. Force declined very rapidly during the first 45 sec. of contraction and much more slowly thereafter. Occlusion of blood flow had no effect on the early rapidly-declining portion of the constant-effort function, but accelerated the decline of the later portion. Occlusion impaired recovery from fatigue, but only slightly. The constant-effort function for the nonpreferred (weaker) hand declined more rapidly than that for the preferred (stronger) hand. Nevertheless, the difference in strength between the two hands was not reflected in feelings of effort in momentary contractions; submaximal loads, held for only 2 sec., did not appear more effortful when exerted with the weaker hand than with the stronger.