Effects of Prior Dynamic Leg Exercise on Static Effort of the Elbow Flexors

The isometric endurance of the elbow flexors was determined in a control condition and subsequent to a maximal effort exercise bout on a cycle ergometer in seven subjects. Maximum voluntary contraction (MVC), peak rate of tension development (+dP/dt), peak rate of tension relaxation (-dP/dt), one-half contraction time, and one-half relaxation time were also measured. Each subject was tested on four occasions: two control and two experimental sessions. During the control sessions each subject held 40% of MVC to exhaustion, whereas the experimental session included a 1-min maximal effort exercise bout on a cycle ergometer 6 min prior to the isometric endurance task. Arterialized blood samples were drawn and analyzed for lactate, pH, PCO2, and PO2. Plasma bicarbonate was calculated from the Henderson-Hasselbalch equation. Subsequent to the cycle ergometer bout, blood lactate concentration rose from 0.8 to 11 mM, pH decreased from 7.43 to 7.20, PCO2 decreased from 40 to 32 Torr, and plasma bicarbonate decreased from 26 to 12 mM. When compared with the control values, no significant changes were evident for any muscle contractile properties following the cycle ergometer bout. However, isometric endurance was significantly reduced from 115.0 +/- 7.2 to 86.3 +/- 7.3 s.(ABSTRACT TRUNCATED AT 250 WORDS)