title: The effect of landing surface on the plantar kinetics of chinese paratroopers using half-squat landing.
abstract: The objective of the study was to determine the effect of landing surface on plantar kinetics during a half-squat landing. Twenty male elite paratroopers with formal parachute landing training and over 2 years of parachute jumping experience were recruited. The subjects wore parachuting boots in which pressure sensing insoles were placed. Each subject was instructed to jump off a platform with a height of 60 cm, and land on either a hard or soft surface in a half-squat posture. Outcome measures were maximal plantar pressure, time to maximal plantar pressure (T-MPP), and pressure-time integral (PTI) upon landing on 10 plantar regions. Compared to a soft surface, hard surface produced higher maximal plantar pressure in the 1(st) to 4(th) metatarsal and mid-foot regions, but lower maximal plantar pressure in the 5(th) metatarsal region. Shorter T- MPP was found during hard surface landing in the 1(st) and 2(nd) metatarsal and medial rear foot. Landing on a hard surface landing resulted in a lower PTI than a soft surface in the 1(st)phalangeal region. For Chinese paratroopers, specific foot prosthesis should be designed to protect the1(st) to 4(th)metatarsal region for hard surface landing, and the 1(st)phalangeal and 5(th)metatarsal region for soft surface landing. Key PointsUnderstanding plantar kinetics during the half-squat landing used by Chinese paratroopers can assist in the design of protective footwear.Compared to landing on a soft surface, a hard surface produced higher maximal plantar pressure in the 1(st) to 4(th) metatarsal and mid-foot regions, but lower maximal plantar pressure in the 5(th) metatarsal region.A shorter time to maximal plantar pressure was found during a hard surface landing in the 1(st) and 2(nd) metatarsals and medial rear foot.Landing on a hard surface resulted in a lower pressure-time integral than landing on a soft surface in the 1(st) phalangeal region.For Chinese paratroopers, specific foot prosthesis should be designed to protect the 1(st) to 4(th) metatarsal region for a hard surface landing, and the 1(st) phalangeal and 5(th) metatarsal region for a soft surface landing.
authors.affiliation: The Department of Orthopedics, Air Force General Hospital , Beijing, China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Li
authors.forename: Ji
authors.initials: J
authors.lastname: Wu
authors.forename: Chao
authors.initials: C
authors.lastname: Zheng
authors.forename: Rong Rong
authors.initials: RR
authors.lastname: Huang
authors.forename: Yuhong
authors.initials: Y
authors.lastname: Na
authors.forename: Fan
authors.initials: F
authors.lastname: Yang
authors.forename: Zengshun
authors.initials: Z
authors.lastname: Wang
authors.forename: Di
authors.initials: D
authors.lastname: Wu
keywords: Half-squat landing; plantar kinetics; plantar pressure; pressure time integral; surface reaction force