An in-school exercise intervention to enhance bone and reduce fat in girls: the CAPO Kids trial

Abstract

The CAPO Kids trial was a 9-mo, controlled, school-based intervention to examine the effects of a novel, brief, high intensity exercise regime on indices of musculoskeletal and metabolic health in pre- and early-pubertal girls.

Methods: A total of 151 pre- and early-pubertal girls (10.6±0.6years), recruited from two different schools consented to participate; 76 in the exercise group (EX) and 75 in the control group (CON). EX performed 10min bouts of thrice-weekly jumping plus capoeira (a Brazilian sport that combines martial art with dance), along with usual physical education (PE) activities. CON continued usual PE alone. Maturity, weight, height, waist circumference, resting heart rate and blood pressure, maximal vertical jump, and aerobic capacity were determined using standard clinical and field measures. Calcaneal broadband ultrasound attenuation (BUA) and stiffness index (SI) were determined from quantitative ultrasonometry. A subsample of children also underwent DXA and pQCT measures. Prior physical activity participation and daily calcium consumption were determined from validated instruments.

Results: EX girls improved BUA more than CON (+4.5% vs. +1.4%, p=0.019). Resting heart rate (-7.2% vs. -1.8%, p<0.01), maximal vertical jump (+13.4% vs. -1.2%, p<0.001), estimated maximal oxygen consumption (+10.6% vs. +1.0%, p<0.001), and waist circumference (+2.7% vs. +5.6%, p<0.001) also improved more for EX than CON.

Conclusion: Ten minutes of high intensity exercise (capoeira and jumping) three times a week in the primary school setting enhances musculoskeletal and metabolic outcomes in pre- and early-pubertal girls without disrupting the academic schedule. The programme, amenable to broad-scale school implementation, would confer meaningful public health benefits.

Keywords: Bone mineral density; Lean mass; Obesity; Paediatric; Physical activity.