A-44 Free Communication/Poster - Oxygen Uptake Kinetics

Abstract

Many investigators utilize exhaustive high-intensity leg cycling exercise (e.g., time trial) to induce fatigue and evaluate associated changes in maximal neuromuscular function. To our knowledge, there are no reports that compare the development of fatigue and recovery of voluntary neuromuscular function to leg and arm locomotor exercise. PURPOSE: To evaluate changes in maximum cycling power (Pmax) before, during, and immediately after exhaustive high-intensity endurance 1) leg and 2) arm cycling. METHODS: Ten trained cyclists performed maximal isokinetic leg cycling trials (3 s, 90 rpm) before and again 0, 0.25, 0.75, 2.0, 3.3, 6.6, and 10 min after an isokinetic leg cycling time trial (TTleg, 10 min, 90 rpm). Four individuals who were upper body endurance trained performed maximal isokinetic arm cycling trials (3 s, 75 rpm) before and again 0, 0.25, 0.75, 2.0, 3.3, 6.6, and 10 min after an isokinetic arm cycling time trial (TTarm, 10 min, 75 rpm). Cycling power was measured with a power meter and fatigue was estimated by comparing relative exercise-induced changes in Pmax. RESULTS: Mean power produced during TTleg was greater than TTarm (360±51 vs. 157±22 W, P<0.01). Heart rate (183±8 vs. 179±17 bpm), overall RPE (19.2±0.9 vs. 18.9±0.6 scale units), limb-specific RPE (19.4±0.7 vs. 18.9±0.6 scale units), and whole-blood lactate (11.4±2.1 vs. 11.8±2.8 mmol/L) measured at the end of the TT did not differ between leg and arm cycling (all P>0.05). After the initial 1/3 of the TT, there was a greater reduction in Pmax for arm cycling compared to leg cycling (20±10 vs. 37±15%, exercise x time P=0.03). However, at the end of the TT, the reduction in Pmax did not differ between leg and arm cycling (45±8 vs. 54±11%, exercise x time p=0.11). At 6.6 post-TT, Pmax had recovered to pre-exercise values for both leg and arm cycling (1±4 vs. 11±14%, simple main effect both P>0.05). CONCLUSION: These preliminary results highlight noticeable differences in the development of fatigue between exhaustive high-intensity endurance exercise involving leg and arm muscle mass. Despite these differences, leg and arm end exercise fatigue were similar between these endurance trained groups and the time courses of recovery for maximal voluntary neuromuscular function generally paralleled one another. Such similarities may reflect PCr resynthesis.