Impact Isolation of Training Shoes

ABSTRACT The increase in popularity of physical activities from fun runs to competitive marathons has lead to a huge industry in sports footwear, which is now worth $20bn annually. There is a resultant increase in injuries, largely due to the repeated and prolonged nature of the impact forces experienced by the leg. Clinical data indicates that the knee is the most common site of running related injury, followed by the lower leg and foot. The complexity of the ankle structure means that injuries are acute and the success rates of replacements are very low. Therefore research in this area is required; to understand both the nature and magnitude of the loads the ankle is subjected to while walking and running, and how these loads may be minimised. This paper investigates the effectiveness of four different running shoes, ranging from a low cost department store own branded shoe, to a high cost specialised running shoe. The shoes are tested on a custom built drop test rig, which can drop the shoes while fitted to a prosthetic foot and ankle. The shoes are dropped to simulate the impacts that occur while walking and running. The rig allows for a range of drop heights, and the ankle to be positioned at various angles to replicate heel strike, flat foot and toe strike. The rig is fitted with force transducers and accelerometers, to record deceleration, and ground reaction force. Also the impacts are recorded on a high speed camera for analysis; this yields the impact velocity, energy absorption and deformation

The happiness - suicide paradox

Suicide is an important scientific phenomenon. Yet its causes remain poorly understood. This study documents a paradox: the happiest places have the highest suicide rates. The study combines findings from two large and rich individual-level data sets—one on life satisfaction and another on suicide deaths—to establish the paradox in a consistent way across U.S. states. It replicates the finding in data on Western industrialized nations and checks that the paradox is not an artifact of population composition or confounding factors. The study concludes with the conjecture that people may find it particularly painful to be unhappy in a happy place, so that the decision to commit suicide is influenced by relative comparisons.Happiness ; Suicide