Pacing Strategies And Physiological Responses To A 5 Min Maximal Cycle Bout

Abstract

Purpose To describe the pacing strategy of experienced cyclists in a 5 min maximal exercise bout and to examine the relationships between selected physiological, electromyographical, and perceptual responses associated with this effort. Methods Six experienced and well-trained competitive cyclists (five males, one female) with a mean (± SD) age, height, and mass of 27.0 ± 4.8 yr, 174.7 ± 8.6 cm, and 71.0 ± 6.5 kg, performed a 5 min maximal exercise bout in a laboratory on a racing cycle which was mounted to a device measuring work rate. Subjects were instructed to work as hard as possible during the bout and were free to determine their work rate throughout. During the exercise bout data were collected for work rate (W), heart rate (HR), oxygen consumption (VO2), electromyography (EMG) of the rectus femoris (RF) and vastus lateralis (VL). Blood lactate concentration (BLC) was assessed 1, 3, and 5-min post-exercise. A repeated-measures ANOVA was used to compare work rate over time with Scheffe post-hoc analysis for the determination of individual differences (p < .05). Pearson correlations were utilized to describe relationships among selected variables. Results Work rate averaged over 30 sec time periods of the 5 min test changed significantly (p < .05). All six subjects selected a pacing strategy characterized by a surge in work rate in the first 30 sec followed by a gradual but significant decline in min 1 to 4 until the last min where a sprint to the end occurred (Figure). HR, respiratory exchange ratio, and post-exercise BLC (182 ± 3 bpm, 1.08 ± 0.07, and 15.5 ± 2.1 mmol/L) indicated that VO2 (3.6 ± 0.4 L/min) was close to or at maximum from min 2–5. EMG activity of the RF and VL was not significantly related to work rate (r = −.54 and .47, p > .05).FigureConclusion It is concluded that pacing strategy is stochastic in an all-out 5 min exercise bout in experienced cyclists yet the physiological responses are near maximum in min 2–5.