ABSTRACTIndividuals with cerebral palsy (CP) are suggested to be less active than typically developing controls (TDs). However, their higher physical activity (PA) energy expenditure during a given activity should be considered. We investigated PA in 10 children and young adults with CP (seven males, 15.4 ± 5.1 years, and Gross Motor Function Classification System [GMFCS] level I/III) and eight TDs (six males, 15.3 ± 4.2 years). PA was assessed with a triaxial accelerometer at baseline and, in participants with CP, during a 3‐month exercise intervention. Data were analyzed for sedentary time, light PA, and moderate‐to‐vigorous PA using both general and, for participants with CP, GMFCS‐specific cutoffs. Statistical analyses included independent and paired sample t‐tests. Based on the general cutoffs, TD and CP participants accumulated on average 516.0 ± 122 and 610 ± 92 min/day sedentary time, 155 ± 37 and 138 ± 46 min/day light PA, and 76 ± 28 and 58 ± 30 min/day moderate‐to‐vigorous PA at baseline. No statistically significant between‐group differences were found (p ≥ 0.081). When applying GMFCS‐specific cutoffs, participants with CP on average accumulated 537 ± 105, 206 ± 61, and 64 ± 31 min/day sedentary time, light PA, and moderate‐to‐vigorous PA. These values differed from their values based on general cutoffs (p ≤ 0.004). The 51 min difference in light PA in favor of the CP group was borderline significant (p = 0.054). In the CP group, PA did not change from baseline to follow‐up (p ≥ 0.098). In conclusion, children and young adults with CP may be as active as TDs, especially when their higher PA energy cost is considered. Muscle strength and gait performance improving exercise did not seem promising in facilitating PA.Trial RegistrationISRCTN69044459