Physical activity and screen time in adolescents transitioning out of compulsory education: a prospective longitudinal study.

BACKGROUND: Within the UK context, it is unclear whether physical activity and screen time changes between completing compulsory education and the period afterwards, and the factors associated with any change. METHODS: A prospective population-based longitudinal design among adolescents (n = 2204 at baseline) was adopted. A self-report questionnaire was administered at baseline (final year of compulsory education) and follow-up (i.e. post compulsory education) to measure physical activity over the previous 7 days and screen time (weekday and weekend) in relation to recommended guidelines. Magnitude of change in physical activity and screen time and key influencing variables associated with changes were analysed. RESULTS: For physical activity, there was a significant change in participants meeting guidelines at baseline but not meeting guidelines at follow-up with 81.0% not meeting guidelines at baseline and follow-up. For screen time, there was no significant change between baseline and follow-up, with 70.6% not meeting guidelines at baseline and follow-up. Gender was associated with the change in physical activity with a decline less likely in females. CONCLUSIONS: Findings reinforce the importance of reducing physical inactivity and sedentary behaviour during this transition. Factors associated with changes in physical inactivity and sedentary behaviour need further investigation.

A meta-analysis of brief high-impact exercises for enhancing bone health in premenopausal women.

UNLABELLED: A snapshot of current evidence from 6 randomised controlled trials for the effects of short bouts of high-impact exercises in 256 women via meta-analysis reveals that ample osteogenic response could be realised at the femoral neck and trochanter of premenopausal women with rest-inserted bouts of few mechanical bone loading cycles. INTRODUCTION: Exercise is an important means of improving bone health and preventing osteoporosis. Brief bouts of simple exercises may be useful for aiding lifestyle compliance to physical activity. This study aimed to review the evidence on the effect of brief, high-impact exercise on bone health among premenopausal women. METHODS: A structured and comprehensive search of databases was undertaken along with hand searching of key journals and reference lists to locate relevant studies published and unpublished up to January 2011. Six randomised controlled trials met predetermined inclusion criteria. Brief high-impact exercises (<30 min) were examined for their effect on bone mineral density (BMD) among premenopausal women. Trial quality was assessed using the Effective Public Health Practice Project quality assessment tool. Study outcomes for analysis, absolute change (grams per square centimetre) or relative change (in percent) in BMD at femoral neck, trochanter and lumbar spine were compared by calculating standardised mean difference (SMD) using fixed- and random effects models. RESULTS: Quality of included trials varied from medium to high on a scale of 1 to 3. Brief bouts of exercise led to significant increases in femoral neck BMD (SMD = 0.64, 95% confidence interval (CI) = 0.38, 0.90, overall effect Z value = 4.84, p = 0.001); a modest increase in trochanteric BMD (SMD = 0.36, 95% CI = 0.10, 0.61, Z value = 2.08, p = 0.04) and no increase in spinal BMD (SMD = 0.04, 95% CI= -0.23, 0.31, Z value = 0.26, p = 0.79). CONCLUSION: Based on the meta-analysis, brief high-impact exercise improves BMD at the hip but not at the lumbar spine. Effectiveness of this form of exercise as a lifestyle physical activity for prevention of osteoporosis should be explored in larger populations.