Analysis of performance determinants in handcycling

Handcycling has become increasingly popular, allowing for a greater mobility and for more training and sports opportunities, and therefore enhancing the social sphere of action of individuals with lower extremity impairments. Research in hand cycling however is scarce. Several determinants that affect performance during hand cycling have not yet been addressed at present. No studies have been conducted that measured and analysed the movement and muscle activation pattern, and the force generation strategies during hand cycling As well, no data are available investigating the influence of functional potential (or the impairment severity) of the user and type of handbike on the movement pattern and the mechanical efficiency during hand cycling. Nevertheless, such data can be important with regards to the optimization of performance in handbike athletes, and the prevention of propulsion related overuse injuries. Therefore the purpose of this research project focused on acquiring new scientific insights in a number of ergonomic aspects in handcycling, more particularly with respect to the influence of the crank rate, the functional potential of the handbike user, and the handbike configuration on the mechanical efficiency. In addition, the project aimed at identifying possible causal relationships between the mechanical efficiency en the force generation effectiveness on the one hand, and the movement and muscle activation pattern, and the force generation strategy on the other hand. The first study investigated the influence of crank rate in handcycling. The results indicated that the freely chosen crank rate is not necessarily the most economical, that high crank rates result in a lower mechanical efficiency at a given power output and that freely chosen crank rates increase with increasing power output levels. The second study aimed at quantifying the torque on the crank axis during handcycling, and to evaluate the consistency of the within cycle torque pattern in hand cycling in subsequent cycles, between different individuals, between different power output levels, and with respect to fatigue. The results suggested a consistent within cycle torque distribution pattern for subsequent cycles and between participants, which is minimally influenced by factors such as power output and fatigue. Thereafter, a handbike ergometer was developed that allows an adequate simulation of ergonomic conditions and mechanical characteristics of hand cycling, a continuous control of workload, the measurement of the three dimensional forces exerted on the crank handles, and the position of the cranks and crank handles, and the possibility to synchronize the force generation measurements with other kinesiological parameters such as kinematics and electromyography and physiological responses. This handbike ergometer was used to conduct a fourth study aiming at evaluating the impact of spinal cord injury lesion level on the force generation strategy and effectiveness. The results illustrated that the force generation effectiveness is mainly associated with the functional availability of the elbow extensors as push force generators and the wrist and finger flexors to grasp the crank handles. On the other hand, trunk strength does not seem to play a crucial role in the effectiveness of force generation during handcycling. Finally, a fifth investigation was carried out to analyze and compare the performance characteristics (mechanical efficiency and peak power output) in 2 handbike configurations: arm powered (AP) and arm trunk powered (ATP) handcycling. The results revealed that ATP handcycling allows for a higher peak power output generation, which is likely caused by a possible trunk involvement. On the other hand, mechanical efficiency was found to be lower during ATP compared to AP handcycling. Potential causes for this lower mechanical efficiency include a greater anterioposterior movement of the shoulder and a different force generation strategy, resulting in a greater muscular demand and therefore also increased energetic requirements during ATP handcycling. Further integrated investigations are necessary to provide a better insight in the relationship mechanical work-metabolic energy expenditure. The movement and muscle activation pattern, in combination with the force generation strategy during hand cycling in realistic conditions can be integrated in a mathematical model, allowing an optimization of the propulsion technique with regards to both energy expenditure and force generation. In addition, such studies allow the investigation of possible causal relationships between the low mechanical efficiency and the incidence of overuse injuries in the shoulder-arm region. As well, individual optimization is possible, taking into consideration the functional potential of the user, the configuration of the handbike and the handbike-user interface.

Publication year:2012

Accessibility:Closed