The effects of treadmill running on the isometric fatigue of the handgrip muscles.

Twelve male subjects, ages 18-32, performed low, moderate, and high intensity systemic treadmill exercise to examine its effect on isometric strength and fatigue of the handgrip muscles. Baseline handgrip values were recorded, as well as maximal oxygen uptake and ventilatory threshold (VT), to determine the intensity for each of the three exercise conditions. Task A involved a 10-min treadmill run at 20% below VT, task B was given at VT, and task C was 20% above VT. Immediately following the endurance treadmill run the subjects were given a 2-min isometric contraction at maximum intensity. Heart rate and blood pressure were also measured. No significant differences were found between control measures and the strength and endurance variables. Rates of fatigue were similar for all conditions, and heart rate and blood pressure remained elevated during the handgrip fatigue task. It is concluded that isometric strength and endurance of non-involved muscles are not affected by prior endurance exercise.