Positive effects on bone mineralisation and muscular fitness after 10 months of intense school-based physical training for children aged 8–10 years: the FIT FIRST randomised controlled trial

Malte Nejst Larsen, Claus Malta Nielsen, Eva Wulff Helge, Mads Madsen, Vibeke Manniche, Lone Hansen, Peter Riis Hansen, Jens Bangsbo, Peter Krustrup

We investigated whether musculoskeletal fitness of school children aged 8-10 years was affected by frequent intense PE sessions. 295 Danish school children aged 8-10 years were cluster randomised to a small-sided ball game group (SSG) (n=96, four schools, five classes), a circuit strength training group (CST) (n=83, four schools, four classes) or a control group (CON, n=116, two schools, five classes). SSG or CST was performed 3×40 min/week over 10 months. Whole-body dual-energy X-ray absorptiometry (DXA) scans were used to determine areal bone mineral density (aBMD), bone mineral content (BMC) and lean body mass (LBM). Flamingo balance, standing long jump and 20-m sprint tests were used to determine muscular fitness. Analysis of baseline-to-10 months change scores showed between-group differences in favour of the interventions in whole-body aBMD (SSG vs CON: 8 mg/cm(2), 95% CI 3 to 13; CST vs CON: 7 mg/cm(2), 95% CI 2 to 13, p<0.05) and leg BMC (SSG vs CON: 11 g, 95% CI 4 to 18; CST vs CON: 11 g, 95% CI 3 to 18, p<0.05). SSG had higher change scores in leg aBMD compared with CON and CST (SSG vs CON: 19 mg/cm(2), 95% CI 11 to 39, p<0.05; SSG vs CST: 12 mg/cm(2), 95% CI 3 to 21, p<0.05), and CST had higher change scores in whole-body BMC compared with CON (CST vs CON: 25 g, 95% CI 10 to 39, p<0.05). Both training types resulted in higher change scores in postural balance (SSG vs CON: 2.4 fewer falls/min, 95% CI 0.3 to 4.5, CST vs CON: 3.6 fewer falls/min, 95% CI 1.3 to 5.9, p<0.05) and jump length (SSG vs CON: 10%, 95% CI 5 to 16%; CST vs CON: 9%, 95% CI 3 to 15%, p<0.05). No between-group differences were observed for sprint performance or LBM (p>0.05). In conclusion, 3×40 min/week with SSG or CST over a full school year improves bone mineralisation and several aspects of muscular fitness of children aged 8-10 years, suggesting that well-organised intense physical education classes can contribute positively to develop musculoskeletal health in young children. NCT02000492, post results.