The Effect of Upper-Body Positioning on the Aerodynamic–Physiological Economy of Time-Trial Cycling

Abstract

Purpose: Cycling time trials (TTs) are characterized by riders’ adopting aerodynamic positions to lessen the impact of aerodynamic drag on velocity. The optimal performance requirements for TTs likely exist on a continuum of rider aerodynamics versus physiological optimization, yet there is little empirical evidence to inform riders and coaches. The aim of the present study was to investigate the relationship between aerodynamic optimization, energy expenditure, heat production, and performance. Methods: Eleven trained cyclists completed 5 submaximal exercise tests followed by a TT. Trials were completed at hip angles of 12° (more horizontal), 16°, 20°, 24° (more vertical), and their self-selected control position. Results: The largest decrease in power output at anaerobic threshold compared with control occurred at 12° (−16 [20] W, P = .03; effect size [ES] = 0.8). There was a linear relationship between upper-body position and heat production (R2 = .414, P = .04) but no change in mean body temperature, suggesting that, as upper-body position and hip angle increase, convective and evaporative cooling also rise. The highest aerodynamic–physiological economy occurred at 12° (384 [53] W·CdA−1·L−1·min−1, ES = 0.4), and the lowest occurred at 24° (338 [28] W·CdA−1·L−1·min−1, ES = 0.7), versus control (367 [41] W·CdA−1·L−1·min−1). Conclusion: These data suggest that the physiological cost of reducing hip angle is outweighed by the aerodynamic benefit and that riders should favor aerodynamic optimization for shorter TT events. The impact on thermoregulation and performance in the field requires further investigation.

An investigation of temperature-sensing textiles for temperature monitoring during sub-maximal cycling trials

“…The participants were part of a larger study investigating body geometry on cycling time trial performance. 29…”

“…The participants were part of a larger study investigating body geometry on cycling time trial performance. 29 During the testing period, participants were asked to maintain their normal training and to refrain from heavy exercise, caffeine, and alcohol during the 24 hours prior to each laboratory visit. Each participant completed their sessions at the same time of day to minimize the effects of circadian and diurnal rhythms on performance and physiological measurements.…”

“…The sub-maximal cycling trials conducted in this work were part of a larger study to better understand thermoregulation during exercise. 29 Temperature measurements using the temperature-sensing E-yarns were recorded whenever possible during these trials. Missing data occurred when there was either a breakage in the E-yarns, a failure in the hardware or connections, or when corresponding skin-mounted thermistor readings were not taken.…”

Sports Coaching in an Online Space: What Can We Learn From Endurance Sport Coaches?

“…Evans et al (2020) contend that, "In sport, where technique and physical skills are paramount, this (RC) could limit the effectiveness of many kinds of coaching practice" (p. 90). Aspects such as aerodynamics (Lukes, Chin & Haake, 2005;Faulkner & Jobling, 2020), bike handling (Zignoli et al, 2021;De Bock & Verstockt, 2021), teamwork and race tactics (Torgler, 2007;Phillips & Hopkins, 2020) have all been shown to have a measurable effect on performance outcomes and are coachable qualities. Yet, as suggested by Evans et al (2020) in the RC context it is more difficult to coach these particular skills.…”

Time Trial positioning in elite cyclists - exploring the physiological effects of adapting to a lower torso position

“…Particularly, in the process of optimising time trial (TT) performance, it is therefore attractive to lower the upper body to reduce the CdA and hence the power output required to sustain a given pace or increase speed for a given power output. The drawback may be that the aerodynamic benefits from lowering the upper body are outweighed by the reported detrimental effects on exercise economy and the ability to maintain power output when the hip-torso angle is compromised (Faulkner & Jobling, 2021;Fintelman et al, 2014;Grappe et al, 1998). The reported impairments in exercise efficiency following a graduate reduction in the hip-torso angle from 24˚ to 0˚ (Faulkner & Jobling, 2021; Fintelman et al, 2014;Grappe et al, 1998) are in stark contrast to observations from elite TT, where riders appear to adopt a torso position much lower than optimal in terms of exercise efficiency.…”