Maximal muscular power: lessons from sprint cycling

Abstract

Maximal muscular power production is of fundamental importance to human functional capacity and feats of performance. Here, we present a synthesis of literature pertaining to physiological systems that limit maximal muscular power during cyclic actions characteristic of locomotor behaviours, and how they adapt to training. Maximal, cyclic muscular power is known to be the main determinant of sprint cycling performance, and therefore we present this synthesis in the context of sprint cycling. Cyclical power is interactively constrained by force-velocity properties (i.e. maximum force and maximum shortening velocity), activation-relaxation kinetics and muscle coordination across the continuum of cycle frequencies, with the relative influence of each factor being frequency dependent. Muscle cross-sectional area and fibre composition appear to be the most prominent properties influencing maximal muscular power and the power-frequency relationship. Due to the role of muscle fibre composition in determining maximum shortening velocity and activation-relaxation kinetics, it remains unclear how improvable these properties are with training. Increases in maximal muscular power may therefore arise primarily from improvements in maximum force production and neuromuscular coordination via appropriate training. Because maximal efforts may need to be sustained for ~15-60 s within sprint cycling competition, the ability to attenuate fatigue-related power loss is also critical to performance. Within this context, the fatigued state is characterised by impairments in force-velocity properties and activation-relaxation kinetics. A suppression and leftward shift of the power-frequency relationship is subsequently observed. It is not clear if rates of power loss can be improved with training, even in the presence adaptations associated with fatigue-resistance. Increasing maximum power may be most efficacious for improving sustained power during brief maximal efforts, although the inclusion of sprint interval training likely remains beneficial. Therefore, evidence from sprint cycling indicates that brief maximal muscular power production under cyclical conditions can be readily improved via appropriate training, with direct implications for sprint cycling as well as other athletic and health-related pursuits.

A Novel Approach of Modelling and Predicting Track Cycling Sprint Performance

“…These fatigue-induced changes can be described by a parallel shift in the F/v profile towards the origin [29,30]. Power output declines in an approximately exponential fashion as a result of increasing fatigue when performing maximal exercise to exhaustion [1,2]. In accordance, we found that the time course of the shift in the F/v profile with fatigue is also exponential.…”

“…In the 500 m and 1000 m-time trials, athletes usually use a standing position in the initial phase (acceleration phase) and a seated position at high speed [2].…”

“…Time trial efforts, particularly the 1 km, are usually executed in an all-out fashion to complete exhaustion [1,2]. This strategy is considered to lead to the best result possible due to the optimal utilisation of physiological capacity [19].…”

“…In track cycling time trial events (contre la montre, against the clock), cyclists compete for the shortest run-time over a given distance, typically 500 m, 1 km or 4 km, with a standing start. Sprint time trials (200 m, 500 m, 1 km) are usually executed in an all-out fashion until complete exhaustion and are indicated by very high maximal and mean power output [1,2]. Competition performance results from the balance of an athlete's energy supply and physical demands [3].…”

Grey Relational Analysis of Lower Limb Muscle Fatigue and Pedalling Performance Decline of Elite Athletes during a 30-Second All-Out Sprint Cycling Exercise

“…It has been suggested that approximately ∼80–85% of the power produced over a pedal cycle is generated during leg extension (i.e., the downstroke), whilst ∼15–20% is produced during leg flexion (i.e. the upstroke) [ 26 ], which may also explain the significant roles of TA, RF, and VAS during sprint cycling. In a broader context, these findings indicate that the anaerobic endurance training of HAM and SOL for improving 30-second all-out sprint cycling exercise performance and the whole anaerobic endurance ability of lower limb muscles is less of a concern as the two muscles are not apt to fatigue during exercise.…”