Crank fore-aft position alters the distribution of work during synchronous recumbent handcycling.

Introduction:

Synchronously operated handcycles should be individually configured towards an athlete, for an optimal athletic performance in terms of power transfer, injury prevention and reductions of drag resistance. However, little research has been done on how to individually configure the handcycle to the athlete.

When exploring the effects of handcycling configuration, both the biomechanical and the physiological effects are relevant to performance.

Study aim: To investigate the effect of four different crank fore-aft positions on elbow flexion and shoulder protraction, the consequent propulsion kinetics, and the physiological responses during handcycling.

Methods:

Twelve able-bodied male participants with little or no previous experience of handcycling volunteered in this study. Crank fore-aft positions were standardised at 94%, 97%, 100% and 103% of the participants' arm length.

Two submaximal 3 min trials were performed at a fixed cadence (70 rpm), in a recumbent handcycle attached to an ergometer at two fixed power outputs (30W and 60W).

Elbow flexion, shoulder protraction, propulsion kinetics and physiological responses of the participants were continuously measured.

Main findings:

• The increase in crank fore-aft position resulted in a decrease in elbow flexion and an increase in shoulder protraction.
• The distribution of work shifted towards an increase of work being performed in the pull phase and a decrease of work being performed in the push phase over the propulsion cycle. 
• This shift was concomitant with an increased peak torque during the pull phase and a reduced peak torque during the push phase.
• At an individual level, participants found different solutions and/or had different preferences regarding the task, which might also be dependent on upper-body physical fitness and motor learning of this relatively new task.
• This emphasizes the importance to not standardize crank fore-aft position based on elbow flexion angle only since this would lead to inconsistent changes with respect to the amount of shoulder protraction between individuals.
• Although a closer crank fore-aft position led to a different kinetic profile, no such effects were found for the physiological variables of VO₂, ME or HR.

Reference:

Vegter RJK, Mason BS, Sporrel B, Stone B, van der Woude LHV, Goosey-Tolfrey VL. Crank fore-aft position alters the distribution of work over the push and pull phase during synchronous recumbent handcycling of able-bodied participants. PLoS One. 2019 Aug 19;14(8):e0220943. DOI: 10.1371/journal.pone.0220943. PMID: 31425557; PMCID: PMC6699671.