Author(s): KAMEDA, M., IIZUKA, S., GOTO, H., HAKAMADA, N., Institution: JAPAN INSTITUTE OF SPORT SCIENCES, Country: JAPAN, Abstract-ID: 543

INTRODUCTION:
Wheelchair athletes require significant upper-body power. Although the relationship between maximal strength and body composition in para powerlifters has been studied [1], the relationship between muscle power and body composition in wheelchair athletes remains unclear, particularly whether regional rather than whole-body composition is more relevant. This study aimed to clarify the relationship between regional body composition and upper-limb push power in wheelchair athletes.
METHODS:
Twenty-one female wheelchair athletes underwent maximal upper-limb push power testing on a servo-controlled isokinetic dynamometer (Medimo Co., Ltd., Japan) in the seated position. Five velocities (0.6, 0.7, 0.8, 0.9, and 1.0 m/s) were tested twice. The maximum value was recorded as absolute maximal push power. Subsequently, the relative maximal push power normalized to body weight was also calculated. Lean body mass (LBM) and fat mass (FM) were obtained using dual-energy X-ray absorptiometry (DXA) for the entire body and specific regions (upper limbs and upper limbs plus trunk). The LBM and FM indices were calculated by dividing the respective values by the square of the height (or arm span when height was unavailable) (kg/m²). Spearman’s rank correlation coefficients were calculated for LBM and FM with absolute maximal push power, and for LBM and FM indices with relative maximal power.
RESULTS:
Absolute maximal push power showed significant positive correlations with upper-limb LBM (ρ = 0.666, p = 0.001), and upper-limb plus trunk LBM (ρ = 0.471, p = 0.031), but was not significantly correlated with whole-body LBM (ρ = 0.382, p = 0.088). Relative maximal push power showed a significant positive correlation with upper-limb LBM index (ρ = 0.535, p = 0.012) but significant negative correlations with whole-body FM index (ρ = −0.714, p < 0.001), upper-limb FM index (ρ = −0.575, p = 0.006), and upper-limb plus trunk FM index (ρ = −0.688, p < 0.001).
CONCLUSION:
These results suggest that a higher upper-limb LBM index is associated with higher relative maximal upper-limb push power, whereas higher fat mass indices are associated with lower relative power. This pattern indicates that excess fat may impose an additional load that does not contribute to power production, thereby reducing relative power when expressed relative to body mass. Our results are consistent with prior work in para-powerlifters reporting a strong relationship between upper-limb LBM and maximal strength [1], and extend this concept by linking upper-limb muscle size to push power outcomes in wheelchair athletes. Notably, upper-limb lean mass was significantly correlated with push power, whereas whole-body lean mass was not, which may reflect the primary reliance on the upper limbs for sport-specific propulsion and wheelchair maneuvers. Collectively, these results suggest that upper-limb lean mass may be an important body-composition factor related to push power performance in wheelchair athletes.
REFERENCE:
[1] Fahs et al., 2020