Steering Does Affect Biophysical Responses in Asynchronous, but Not Synchronous Submaximal Handcycle Ergometry in...

Area of Science:

• Biomechanics
• Exercise Physiology
• Rehabilitation Engineering

Background:

• Real-world handcycling integrates propulsion and steering.
• Modern handcycles typically feature synchronous cranks, unlike earlier designs.
• Arm ergometers, used for training and testing, lack steering and often have asynchronous cranks.

Purpose of the Study:

• To investigate the impact of combined propulsion and steering on synchronous and asynchronous handcycle ergometry.
• To compare the mechanical and metabolic efficiency of different handcycling configurations.
• To hypothesize that asynchronous handcycling with steering is the least mechanically efficient due to compensatory movements.

Main Methods:

• Sixteen healthy male novices participated in a lab-based experiment.
• A specialized handcycle ergometer with 3D force sensors and natural steering capabilities was used.
• Four submaximal steady-state conditions (60 rpm, ~35 W) were tested: synchronous/fixed steering, synchronous/steering, asynchronous/fixed steering, and asynchronous/steering.

Main Results:

• Synchronous handcycling, with or without steering, showed no significant difference in velocity, torque, or power, maintaining metabolic efficiency.
• Asynchronous handcycling with steering led to reduced mechanical efficiency, increased steering axis velocity, and less effective torque/power.
• Neuromuscular compensation strategies appear necessary in asynchronous mode to counteract unwanted steering movements.

Conclusions:

• Synchronous crank setups are recommended for practicing or testing real-life handcycling, as performance is unaffected by steering.
• Asynchronous handcycling requires different techniques and results in higher metabolic demands, making it less suitable for standardized testing.
• The findings highlight the importance of crank synchronicity for efficient handcycle ergometry and performance assessment.