Comparison of muscle strength, sprint power and aerobic capacity in adults with and without cerebral palsy.

Objective: To compare: (i) muscle strength, sprint power and maximal aerobic capacity; and (ii) the correlations between these variables in adults with and without cerebral palsy.

Design: Cross-sectional study.

Subjects: Twenty adults with and 24 without cerebral palsy.

Methods: Isometric and isokinetic knee extension strength, sprint power (mean power over the 30s (P30)), peak aerobic power output (PO(peak)) and oxygen uptake (VO(2peak)) were determined. Regression analysis was used to investigate correlations between parameters.

Results: Adults with cerebral palsy had significantly lower strength (53-69%) and P30 (67%) than adults without cerebral palsy, but similar PO(peak) and VO(2peak). In adults without cerebral palsy the only significant correlations, albeit weak, were between P30 and isometric (R2 = 0.34) or isokinetic strength (R2 = 0.20), as well as the correlation between P30 and VO(peak) (R2 = 0.26) or PO(peak) (R2 = 0.36). Stronger correlations were found in the group with cerebral palsy between P30 and isometric (R2 = 0.52) and isokinetic strength (R2 = 0.71) and between P30 and VO(peak) (R2 = 0.75) or PO(peak) (R2 = 0.94).

Conclusion: In contrast to aerobic capacity, strength and P30 are reduced in (active) people with cerebral palsy. Stronger correlations were found between strength, P30 and PO(peak) in adults with cerebral palsy. Therefore, muscle strength may be the limiting factor in adults with cerebral palsy for activities involving the lower extremities, such as cycling.