Report

Crank length alters kinematics and kinetics, yet not the economy of recumbent hand-cyclists.

Crank length manipulations alter the kinetics and kinematics of recumbent hand cyclists without influencing their physiological economy.

Lead academic:
Barry Mason
Additional academics:
Benjamin Stone, Martin Warner, Vicky Tolfrey
Funder:
English Institute of Sport and British Cycling.

Introduction:

Handcycling performance is dependent on the physiological economy of the athlete; however, hand-bike configuration and the biomechanical interaction between the two are also vital.

Although there are numerous components to a hand-bike, the length of the crank arms was recently identified by handcycling experts as an area of configuration that could have a substantial bearing on performance. However, the effect of crank length on handcycling performance has received limited empirical research.

Study aim: To explore the impact of crank length on physiological and biomechanical aspects of recumbent handcycling at fixed linear handgrip speeds and sport-specific intensities in highly trained hand-cyclists.

Methods:

Nine competitive hand-cyclists completed a 3-minute trial in an adjustable recumbent hand-bike in four crank length settings (150, 160, 170 & 180 mm) at 70% peak power output. Handgrip speed was controlled (1.6 m·s-1) across trials with cadences ranged from 102 to 85 rpm.

Physiological economy, heart rate, and ratings of perceived exertion were monitored in all trials. Handcycling kinetics were quantified using an SRM (Schoberer Rad Messtechnik) power meter, and upper limb kinematics were determined using a 10-camera VICON motion capture system. 

Main findings:

  • Physiological responses were not significantly affected by crank length.
  • Greater torque was generated (P < .0005) and peak torque occurred earlier during the push and pull phase (P ≤ .001) in longer cranks.
  • The timing and orientation of shoulder flexion, shoulder abduction, and elbow extension were significantly altered in different crank lengths.
  • At constant handgrip speeds (and varying cadence) highly trained hand-cyclists may select crank lengths between 150 and 180 mm without affecting their physiological performance.
  • Until further research, factors such as anthropometrics, comfort, and self-selected cadence should be used to facilitate crank length selection in recumbent hand-cyclists.

Reference:

Mason BS, Stone B, Warner MB, Goosey-Tolfrey VL. Crank length alters kinematics and kinetics, yet not the economy of recumbent handcyclists at constant handgrip speeds. Scand J Med Sci Sports. 2021 Feb;31(2):388-397. DOI: . Epub 2020 Nov 3. PMID: 33079394.