Effects of two 9-month sports programmes (four or two sessions per week) on level of daily physical activity (PA), fat mass (FM), and physical fitness were assessed in children with spastic cerebral palsy (CP; n = 20, 9.2 +/- 1.4 yr), randomly assigned to an experimental and control group after matching. Four sessions per week tended to increase PA ratio (24-h energy expenditure/sleeping (resting) energy expenditure) after 9 months from 1.34 +/- 0.25 to 1.55 +/- 0.18 (P = 0.07; not different versus controls). FM increased continuously in the control group (after 9 months + 1.1 +/- 1.6 kg, P < 0.05), whereas the experimental groups showed no changes. Training (respectively four and two sessions) increased peak aerobic power 35% (P < 0.01; P < 0.05 versus controls) and 21% (P < 0.01; P = 0.17 versus controls). Results also suggest that training has a favourable effect on isokinetic muscle strength. No training-related effects were found on anaerobic power. It was concluded that although aerobic training has a limited effect on PA in children with CP, it may prevent deterioration in body composition and muscle strength. Furthermore, training has a favourable effect on peak aerobic power.