Eccentric cycling ergometer to address skeletal muscle dysfunction in hospitalised patients: Ergometer design, construction and demonstration
Purpose Continuous eccentric cycling has demonstrated metabolic efficiency when compared with equivalent concentric workloads. The profile of continuous eccentric cycling is well suited to hospitalised patients, however, its application has been restricted to outpatient settings as ergometers appropriate for the acute setting are currently unavailable. The aim of this study was to construct an eccentric cycle ergometer specifically for use in an acute care hospital ward and demonstrate its performance in healthy subjects. Methods An eccentric cycle ergometer (asynchronous 125 W motor) was constructed with strain gauge technology (SRM PowerMetre) to allow instantaneous biofeedback to the user. Ten healthy participants (20-64 years) were used to test the capacity of the ergometer to maintain consistent force production (repeated 5 min duration) with appropriate physiology responses (heart rate, minute ventilation, arterial saturation, electromyography and muscle tissue oxygen saturation) for low to moderate eccentric workloads. Results Eccentric power output was consistently achieved without mechanical or ergonomic issues for two workloads (31.1±5.7 W and 56.6±8.8 W, respectively). Participant heart rate (rest: 68±13 bpm) and minute ventilation (rest: 12.4±3.5 L/min) increased incrementally with workload 1 (HR: 83±16 bpm VE: 21.76±6.5 L.min-1, p<0.001 vs rest) and workload 2 (HR: 94±14 bpm VE: 26.5±8.9 L/min, p<0.001 vs rest) while local muscle oxygen saturation remained unchanged for both workloads. Conclusion This study describes the successful construction of an eccentric cycle ergometer and demonstrated the efficacy of the ergometer to deliver constant eccentric workloads in healthy adults. Eccentric cycling could be potentially provided to hospitalised patients using this ergometer.
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