Biomechanical and physiological aspects of handcycling propulsion under various exercise modalities in able-bodied participants

Oliver Jan Quittmann*

*Corresponding author for this work

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Abstract

Handcycling is an efficient and aerobically demanding exercise for improving endurance in individuals with an spinal cord injury (SCI) or amputation of the lower limb/s. Even though handcycling was found to be mechanically less straining when compared to manual wheelchair propulsion, Paralympic athletes are prone to overuse injuries of the upper extremity. Physiological aspects of handcycling exercise during cross-sectional and longitudinal studies have primarily investigated aerobic metabolism in terms of maximal oxygen consumption (V̇O2max) and efficiency. Biomechanical aspects of handcycling propulsion demonstrated alterations due to the handbike setup and different intensities. However, studies combining crank kinetics, joint kinematics and muscular activity are primarily based on single-case studies. Hence, this thesis aimed to assess anaerobic metabolism in terms of lactate kinetics and maximal lactate accumulation rate (V̇Lamax) and examine the complex biomechanics underlying handcycling propulsion in several participants.
Two studies were performed in n = 12 and n = 18 able-bodied triathletes, respectively. In the first study, lactate kinetics, crank kinetics, joint kinematics and muscular activity were measured during three exercise modalities: an incremental step test until volitional exhaustion, a 15-s all-out sprint test and a 30-min continuous load trial at the individual lactate threshold (P4). The tests were performed in a recumbent racing handcycle (Shark S, Sopur, Sunrise Medical, Malsch, Germany) that was mounted on an ergometer (8 Hz, Cyclus 2, RBM electronic automation GmbH, Leipzig, Germany). Lactate kinetics were determined by using an enzymatic-amperometric sensor chip system (Biosen C-Line, EKF-diagnostics GmbH, Barleben, Germany) and adequate interpolation approaches. Tangential crank torque was measured using a power meter (1000 Hz, Schoberer Rad Messtechnik GmbH, Jülich, Germany) installed in the crank. Joint kinematics of the shoulder, elbow, wrist and trunk were calculated according to the Upper Limb Model of Vicon Nexus and ISB recommendation by using a 3D motion capturing system (100 Hz, Vicon Nexus 2.3, Vicon Motion Systems Ltd., Oxford, UK). Surface electromyography (sEMG) was performed for ten muscles of the upper extremity and trunk using a wireless sEMG system (1000 Hz, DTSEMG Sensor®, Noraxon Scottsdale, Arizona, USA). Additionally, different sEMG normalisation procedures were compared to determine adequate maximal voluntary isometric contraction (MVIC) positions. In the second study, peak power output and V̇Lamax were compared between handcycling and conventional (leg) cycling in terms of reliability, differences between and correlations among extremities.
V̇Lamax was identified as a promising parameter in handcycling exercise testing, since V̇Lamax attained high reliability and correlated with both aerobic and anaerobic performance. Moreover, V̇Lamax was found to be extremity-specific which might be relevant for exercise testing in endurance sports with an emphasis on both extremities (e. g. rowing and cross-country skiing). Based on the biomechanical measurements, the pull phase was found to increase in work distribution with exercise intensity and duration. The muscular activation patterns (MAPs) of the examined muscles were used to identify their function in propulsion cycle and assess their sensitivity to fatigue. As the initiator of the pull phase, the posterior part of M. deltoideus (DP) was found to be most affected by exercise intensity and duration which highlights the necessity for additional conditioning. Whereas some muscles can be normalised by sport-specific MVICs, some muscles should be normalised muscle-specifically. Future studies should replicate these studies, examine the effect of deliberate training on V̇Lamax and investigate handcycling biomechanics in several elite SCI handcyclists/paratriathletes.
Translated title of the contributionBiomechanische und physiologische Aspekte des Handcyclings bei unterschiedlichen Belastungsmodalitäten
Original languageEnglish
Place of PublicationKöln
PublisherDeutsche Sporthochschule Köln
Number of pages217
DOIs
Publication statusPublished - 2019

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