Influence of the handrim diameter on heart rate and blood lactate in a world-class wheelchair athlete

Abstract

The aim of the present study was focused on the determination of the effect of the diameter of the hand-rim of the racing wheelchair on the heart rate and blood lactate produced at the competition speeds. The study was carried out with a world-class athlete, that made a total of 9 series of 5 minutes, at maintained speed, recovering 10 min between series and testing 3 hand-rim (34, 36 and 38cm of diameter) at 3 different speeds (20, 22 and 24 Km/h). Heart rate and blood lactate was measured. An ANOVA was made and we found statistically significant differences (p <0.0001) on Heart Rate (HR), between the different speeds and between the different diameters of hand-rim. Besides that we also found significant interaction (p <0.0001) among the factors Speed and Diameter of hand-rim. In general terms it is possible to conclude that at 20 Km/h the most efficient hand-rim (minor HR and blood lactate) was the one of 36 cm, whereas the least efficient was the one of 34 cm. Both 22 and 24 Km/h the most efficient hand-rim was that of 34 cm whereas the least efficient was that of 38 cm. We can conclude that the election of the optimal diameter of hand-rim supposes such improvement in the mechanical efficiency that in case of the studied athlete, his maximum sustainable speed with the hand-rim of 36 cm would be about 23 Km/h whereas with the hand-rim of 34 cm would be 24 Km/h. KEY WORDS: Wheelchairs. Track and field. Mechanical efficiency.