Journal Logo

F19U FREE COMMUNICATION/POSTER SKELETAL MUSCLE II

PREVIOUS ARM EXERCISE LEADS TO GREATER INTERSTITIAL POTASSIUM ACCUMULATION AND EARLIER FATIGUE OF LEG MUSCLE

Nordsborg, N1; Mohr, M1; Pedersen, L D.1; Nielsen, J J.1; Bangsbo, J1

Author Information
Medicine & Science in Sports & Exercise: May 2001 - Volume 33 - Issue 5 - p S263
  • Free

It has been observed that previous arm exercise leads to a more rapid decrease in muscle pH and a greater potassium release during subsequent leg exercise. The present study examined how potassium kinetics in leg muscle was affected by prior arm exercise. Six microdialysis probes were inserted in m. vastus lateralis of six healthy male volunteers on two separates occasions. The subjects performed one-legged knee extensor exercise (60.3 ± 1.2 (± SEM) W) to exhaustion on one occasion without (Control, C) and at another occasion with (Arm, A) 15 min of prior intense intermittent arm-cycling exercise. Before and during the exercise dialysate from the microdialysis probes was collected frequently. Based on the dialysate potassium concentration and probe recovery the intersitial potassium concentration was determined. Time to fatigue was shorter (P < 0.05) in A than in C (2.7 ± 0.3 vs. 3.9 ± 0.3 min). Before the exercise the interstitial potassium concentration in A and C was not different (4.9 ± 0.3 and 4.3 ± 0.1 mM) but after 1.25 min of exercise it was higher (P < 0.05) in A than in C (9.8 ± 0.6 vs. 8.4 ± 0.7 mM). At the point of fatigue there was no difference (P>0.05) in interstitial potassium concentrations between A and C (11.0 ± 0.8 vs. 12.3 ± 0.5 mM). The present study demonstrates that arm exercise prior to exhaustive one-legged knee extensor exercise leads to a greater rate of increase in interstitial potassium concentration and a significant reduction in time to fatigue. These findings suggest that the development of muscular fatigue is associated with a rise in the interstitial potassium concentration in the exercising muscle.

©2001The American College of Sports Medicine