physical activity exercise humans male body mass index physiology health female ireland adult this review training heart rate psychology children older adults adolescent sports sciences biomechanics body composition medicine and health sciences obesity systematic review Movement public health influence Muscle, Skeletal blood pressure Muscle Strength rehabilitation risk factors middle aged young adult body weight ageing physical fitness body-mass people rugby union sport 5 years elite education measurement patients ph.d. trinity college dublin physical activity study physiotherapy Running women three-dimensional adolescents diet energy expenditure health and physical activity health promotion personal sensing child future irish mental health physical exercise self report sports cardiovascular disease dietary intake outcome measures Self Efficacy well-being aged athletes cross-sectional studies fatigue intervention motor activity