Muscle endurance and power spectrum of the triceps brachii in wheelchair marathon racers with paraplegia

Objective: To investigate differences in triceps brachii endurance and electrical activity between elite marathon and recreational wheelchair athletes with paraplegia. Design and methods: Nine male elite wheelchair athletes between 20 and 46 years of age (average 29.0±8.2 years) with complete (ASIA-A) T4-L1 paraplegia were compared to a group of six male height- and weight-matched recreational wheelchair athletes with similar ages and injuries. Right triceps brachii maximum voluntary contraction (MVC), as well as the duration of the ability to maintain a 50% MVC were determined for all subjects. Median frequency (MF) and mean power frequency (MPF) were evaluated with fast Fourier transform spectrum analysis. MF and MPF rates of change were calculated and compared with the Student's t-test. Setting: Department of Rehabilitation Medicine, University of Occupational and Environmental Health, Japan. Results: Right triceps brachii MVCs of the marathoners (42.4±8.8 N m (range 33-55 N m)) and recreational athletes (41.6±9.3 N m (range 32-56 N m)) did not differ significantly (P=0.63). Endurance, however, did. All of the athletes, but none of the control subjects, were able to maintain a 50% MVC contraction of the right triceps brachii for 2 min (the average contraction duration in the latter group was 75.5±16.2 s). MF and MPF of the triceps brachii decreased linearly in both groups, but the slopes in the marathoners (-8.9±4.6 (-3.8 to -16.4) and -9.7±4.6 (-4.0 to -17.2)%/min, respectively) were statistically less steep than those in the recreational athletes (-22.3±8.2 (-9.6 to -31.4) and -21.2±6.4 (-11.4 to -28.6)%/min, respectively). Conclusion: Elite marathoners and active wheelchair users have similar triceps brachii strength. The marathoner's triceps brachii, however, display a significantly improved endurance and a slower decline of MF and MPF with time than do those of their recreational athlete control group.