Arm Cranking Economy in Spastic Cerebral Palsy: Effects of Different Speed and Force Combinations Yielding the Same Mechanical Power

Abstract

To determine optimal arm crank speed for subjects with cerebral palsy (CP), and whether it differs at high or low power output (PO), the cardiopulmonary cost and economy of cranking at 20, 30, and 40 rpm under a low (0.09 W · cm−1 arm span) and a high (0.12 or 0.18 W · cm−1 arm span) PO were measured in 11 adolescents (14.3 ± 2.4 years) with spastic diplegic CP. Data were analyzed using an ANOVA for repeated measures and post hoc (for between-speed differences) using Tukey’s test for honestly significant differences. Crank speed did not affect the cardiopulmonary cost nor economy at low PO. Under high PO, net economy at 30 rpm (12.2%) was significantly (p = .001) higher than at 20 rpm (10.2%), with a trend (p = .055) to also be higher than at 40 rpm (11.1%). Gross economy showed a similar pattern. These results suggest that cranking at 30 rpm under high PO may be more economical than cranking at 20 or 40 rpm.