The effect of a low-load plyometric running intervention on leg stiffness in youth with cerebral palsy: A randomised controlled trial

Abstract

Aim: To determine whether a running intervention utilising plyometric activities improved leg stiffness in youth with cerebral palsy (CP), GMFCS levels I and II.

Method: This stratified randomised controlled trial examined the lower limb kinetics and kinematics of a sample of youths with CP during sub-maximal hopping and running, prior to and immediately following a 12-week running intervention that incorporated low load plyometric training. Included participants were 13 in the control group (mean age 13 years 2 months [SD 2 years 7 months]; six males; nine GMFCS level I; six unilateral) and 18 in the intervention group (mean age 12 years 9 months [SD 2 years 10 months]; 13 males; 11 GMFCS level I; nine unilateral). Derived variables included three-dimensional leg stiffness as well as resultant ground reaction force and change in leg length. Generalised linear mixed models were developed for statistical analysis.

Results: At follow-up the intervention group had greater leg stiffness than the control group during submaximal hopping (Intervention median = 3278Nm^-1; Control median = 1556Nm^-1; p < 0.01). At follow-up, participants in the intervention group in GMFCS Level I had greater leg stiffness than the control group during jogging (Intervention mean=38.84 (SD=25.55); Control mean=29.38 (SD=11.11); t = 2.61 p = 0.01).

Interpretation: A running training intervention which includes plyometric activities can improve leg stiffness in young people with CP, especially those in GMFCS level I.

Keywords: Biomechanics; Cerebral palsy; Gait; Leg stiffness; Plyometrics; Running.