RESUMO
Single-leg cycling (SLC) allows for a greater muscle specific exercise capacity and therefore provides a greater stimulus for metabolic and vascular adaptations compared to double-leg cycling (DLC). The purpose of this investigation was to compare the cardiovascular, peripheral, and metabolic responses of counterweighted (10kg) SLC to DLC in a healthy older male population. Eleven males (56-86 years) performed two cycling modalities consisting of DLC and SLC. For each modality, participants performed 4-minute cycling trials (60rpm) at three work rates (25, 50, 75W). Repeated measures ANOVAs and paired samples T-test (α=0.05) were used to assess differences in physiological and perceptual responses. Heart rate (100±21 vs. 103±20bpm), oxygen uptake (12.1±3.6 vs. 11.7±2.8mL*kg-1*min-1) and mean arterial pressure (104±13 vs. 108±12mmHg) were not different between DLC and SLC, respectively. Femoral blood flow was greater during SLC at 50W (741.4±290.3 vs. 509.0±230.8mL/min) and 75W (993.8±236.2 vs. 680.6±278.0mL/min) (p≤0.01). Furthermore, carbohydrate oxidation during SLC was 30-40% greater than DLC across work rates (p≤0.011). Whole body rating of perceived exertion (RPE) at 25 and 50W were not different (p=0.065), however, whole body RPE at 75W and leg RPE were higher for SLC at all intensities (p≤0.018). Liking scores were not different between cycling modalities (p=0.060). At low and moderate intensities, SLC provides a greater peripheral stress with no difference in cardiovascular responses compared to DLC in a healthy older adult male population. Thus, SLC may be a feasible exercise modality to maximize peripheral adaptations for healthy and diseased (i.e. peripheral vascular disease/cardiovascular disease) older population.
RESUMO
PURPOSE: Although difficult to coordinate, single-leg cycling allows for greater muscle-specific exercise capacity and subsequently greater stimulus for metabolic and vascular adaptations compared to typical double-leg cycling. The purpose of this investigation was to compare metabolic, cardiovascular and perceptual responses of double-leg cycling to single-leg cycling with and without the use of a counterweight. METHODS: Ten healthy individuals (age 22 ± 2 years; body mass 78.0 ± 11.2 kg; height 1.8 ± 0.1 m) performed three cycling conditions consisting of double-leg cycling (DL), non-counterweighted single-leg cycling (SLNCW) and single-leg cycling with a 97 N counterweight attached to the unoccupied crank arm (SLCW). For each condition, participants performed cycling trials (80 rpm) at three different work rates (40, 80 and 120 W). Oxygen consumption (VO2), respiratory exchange ratio (RER), heart rate (HR), femoral blood flow, rating of perceived exertion (RPE) and liking score were measured. RESULTS: VO2 and HR were similar for DL and SLCW conditions. However, during SLNCW, VO2 was at least 23 ± 13 % greater and HR was at least 15 ± 11 % greater compared to SLCW across all three intensities. Femoral blood flow was at least 65.5 ± 43.8 % greater during SLCW compared to DL cycling across all three intensities. RPE was lower and liking scores were greater for SLCW compared to SLNCW condition. CONCLUSION: Counterweighted single-leg cycling provides an exercise modality that is more tolerable than typical single-leg cycling while inducing greater peripheral stress for the same cardiovascular demand as double-leg cycling.
