Effects of previous exercise with arms or legs on metabolism and performance in exhaustive exercise.

The ability of additional muscles to perform after certain other muscles of the body had been exercised to exhaustion was studied in three male subjects. Exhaustive exercise was performed in two series: series L-A, a bout of leg exercise preceded a bout of arm exercise; series A-L, arm preceded leg (6-min recovery between bouts). Biopsies were taken during the course of each experiment from both the deltoideus and vastus lateralis muscles for determination of ATP, creatine phosphate, lactate, and pyruvate. Exhaustive exercise led to marked elevations in lactate and decreases in ATP and CP in exercised muscle and marked increases in blood lactate concentration. Similar changes, especially in lactate, were observed during and after the first exercise bout in nonexercised muscle. When arm or leg exercise was performed as the second bout, decreases in performance time were observed as compared to performance as the initial bout. It is suggested that the performance potential of muscle is decreased because of internal changes elicited by elevated blood lactate and/or blood H+ concentrations brought about by other muscle groups previously exercised to exhaustion.