Prolonged cycling for two hours significantly decreased power output at the moderate-to-heavy intensity transition by 21 W compared to pre-exercise baseline.
Does prolonged moderate-intensity cycling reduce power output at the moderate-to-heavy intensity transition in endurance-trained athletes?
Prolonged moderate-intensity cycling reduces the power output at the moderate-to-heavy intensity transition due to decreased efficiency, highlighting the need for individual assessments of athlete durability.
Mean Difference: -21
Absolute Event Rate: 196% vs 217%
p-value: p=<0.0001
Abstract Purpose To determine the effect of prolonged exercise on moderate-to-heavy intensity transition power output and heart rate. Methods Fourteen endurance-trained cyclists and triathletes took part in the present investigation (13 males, 1 female, V·O 2 peak 59.9 ± 6.8 mL . kg −1. min −1 ). Following a characterisation trial, participants undertook a five-stage incremental step test to determine the power output and heart rate at the moderate-to-heavy intensity transition before and after two hours of cycling at 90% of the estimated power output at first ventilatory threshold (VT 1 ). Results Power output at the moderate-to-heavy intensity transition significantly decreased following acute prolonged exercise when determined using expired gases (VT 1 , 217 ± 42 W vs. 196 ± 42 W, P < 0.0001) and blood lactate concentrations (LoglogLT, 212 ± 47 W vs. 190 ± 47 W, P = 0.004). This was attributable to loss of efficiency (VT 1 , -8 ± 10 W; LoglogLT, − 7 ± 9 W) and rates of metabolic energy expenditure at the transition (VT 1 , − 14 ± 11 W; LoglogLT, − 15 ± 22 W). The heart rate associated with the moderate-to-heavy intensity transition increased following acute prolonged exercise (VT 1, 142 ± 9 beats . min −1 vs. 151 ± 12 beats . min −1 , P < 0.001; LoglogLT, 140 ± 13 beats . min −1 vs. 150 ± 15 beats . min −1 , P = 0.006). Conclusion These results demonstrate the external work output at the moderate-to-heavy intensity transition decreases during prolonged exercise due to decreased efficiency and rates of metabolic energy expenditure, but the associated heart rate increases. Therefore, individual assessments of athlete ‘durability’ are warranted.
Stevenson et al. (Tue,) conducted a other in Healthy endurance-trained cyclists and triathletes (n=14). Prolonged cycling vs. Pre-exercise baseline was evaluated on Power output at the moderate-to-heavy intensity transition (VT1) (MD -21 W, p=<0.0001). Prolonged cycling for two hours significantly decreased power output at the moderate-to-heavy intensity transition by 21 W compared to pre-exercise baseline.