The POWER PE study was an 8-mo, randomized, controlled, school-based exercise intervention designed to apply known principles of effective bone loading to practical opportunities to improve life-long musculoskeletal outcomes. A total of 99 adolescents (46 boys and 53 girls) with a mean age of 13.8 ± 0.4 yr (peri-to postpubertal) volunteered to participate. Intervention subjects performed 10 min of jumping activity in place of regular physical education (PE) warm up. Control subjects performed usual PE warm-up activities. Bone mass (DXA and QUS) was assessed at baseline and follow-up along with anthropometry, maturity, muscle power, and estimates of physical activity and dietary calcium. Geometric properties (such as femoral neck [FN] moment of inertia) were calculated from DXA measures. Boys in the intervention group experienced improvements in calcaneal broadband ultrasound attenuation (BUA) (+5.0%) and fat mass (−10.5%), whereas controls did not (+1.4% and -0.8%, respectively). Girls in the intervention group improved FN BMC (+13.9%) and lumbar spine (LS) BMAD (+5.2%) more than controls (+4.9% and +1.5%, respectively). Between-group comparisons of change showed intervention effects only for whole body (WB) BMC (+10.6% versus +6.3%) for boys. Boys in the intervention group gained more lean tissue mass, trochanter (TR) BMC, LS BMC, and WB BMC and lost more fat mass than girls in the intervention group (p < 0.05). Ten minutes of jumping activity twice a week for 8 mo during adolescence seems to improve bone accrual in a sex-specific manner. Boys increased WB bone mass and BUA, and reduced fat mass, whereas girls improved bone mass at the hip and spine.

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Line dancing, particularly in concert with regular squats and foot stamping, is a simple and appealing strategy that may be employed to reduce lower extremity bone loss, and improve lower limb muscle strength and balance, in independent living, otherwise healthy, postmenopausal Caucasian women.

Deimatic behaviours, also referred to as startle behaviours, are used against predators and rivals. Although many are spectacular, their proximate and ultimate causes remain unclear. In this review we aim to synthesise what is known about deimatic behaviour and identify knowledge gaps. We propose a working hypothesis for deimatic behaviour, and discuss the available evidence for the evolution, ontogeny, causation, and survival value of deimatic behaviour using Tinbergen's Four Questions as a framework. Our overarching aim is to direct future research by suggesting ways to address the most pressing questions in this field.