ISOMETRIC STRENGTH, SPRINT POWER, AND AEROBIC POWER IN INDIVIDUALS WITH A SPINAL-CORD INJURY

This study investigated in rather specific wheelchair tests the relationships among estimates of isometric upper-body strength (F(iso)), sprint power (P30), aerobic power (VO2peak), and maximal power output (PO(aer)) in a group of 44 men (age 34 +/- 12 vr) with long-standing spinal cord injuries ranging from C4/C5 to L5. F(iso) was defined as the maximum force that could be exerted on the blocked rims of a stationary wheelchair ergometer. The estimation of P30 involved the measurement of the mean power during a 30-s all-out sprint test on the same wheelchair ergometer. VO2peak and PO(aer) were determined as the peak oxygen uptake and highest sustained power output during a discontinuous progressive maximal exercise test on a motorized treadmill, while subjects used their own daily use wheelchair. F(iso) ranged from 1.5 N . kg-1 (mean of both arms) in the group with quadriplegia to 3.4 N . kg-1 in the group with lowest-lesions, and P30 ranged from 0.5 to 1.5 W . kg-1 among the subjects. VO2peak ranged from 13.6 ml . kg-1 . min-1 in the group with quadriplegia to 31.3 ml . kg-1 . min-1 in the group with lowest-lesions, and PO(aer) ranged from 0.4 to 1.1 W . kg-1. Strong positive relationships (r = 0.81-0.92) were demonstrated among all variables. Regression equations among variables were calculated: P30 = 0.51 F(iso) - 0.18 (R2 = 0.75); PO(aer) = 0.34 F(iso) - 0.02 (R2 = 0.66); PO(aer) = 0:67 P30 + 0.11 (R2 = 0.81): VO2peak = 6.52 F(iso) + 4.15 (R2 = 0.76); VO2peak = 12.03 P30 + 7.43 (R2 = 0.77); VO2peak = 16.81 PO(aer) + 6.44 (R2 = 0.84). It was concluded that strong positive associations exist among upper-body isometric strength, sprint power, and aerobic power in individuals with spinal cord injuries, which is probably due to the shared dependency on active muscle mass. Hence, it seems that measurement of merely one of all selected variables might be sufficient to describe (within certain limits) the physical capacity of individuals with spinal cord injuries.