Influence of Cold-water Immersion on Biomechanics of Drop-landing

Abstract

Exposure of humans to cold environments results in pronounced alterations in many physiologic systems when tissues are cooled. There are recreational situations and military exercises (e.g. fording cold-water rivers, streams, and tidal pools) that result in reducing lower extremity temperatures. Many popular winter sports (e.g. football, soccer, skiing, and cross country running) also present challenges to the body, that in particular lead to cooling of extremities. Little is known about the cold effects on exercise performance from a mechanical perspective. PURPOSES: to investigate the influence of different levels of cold-water immersion on drop-landing mechanics. METHODES: Ten healthy college male students were recruited in the study. On four separate days, subjects performed drop-landings from a 0.6 m platform to a force platform following 30-minute immersion in thermoneutral water (N) (34°C) to the hip-joint level and in cold-water (20°C) to the ankle- (A), knee- (K), and hip- (H) joint levels. Ground reaction forces and 3-D video data were collected. Sagittal plane analysis was performed. Vertical ground reaction force (VGRF), whole body stiffness, mechanical works at ankle, knee, and hip joints and total lower extremity mechanical works were calculated. One way repeated measures ANOVA was used to determine differences among the four conditions (α = 0.05). RESULTS: Compared to N condition, A showed no difference of VGRF, whole body stiffness, and mechanical works. Both K and H showed less mechanical work at ankle level than N. Both K and H had less total mechanical works than N. Furthermore, H showed lesser VGRF and whole body stiffness than N. CONCLUSIONS: As the level of cold water immersion increases, mechanical changes during drop-landing become prominent. Cold water immersion at ankle level does not affect the VGRF, mechanical works of lower extremity, and whole body stiffness. Cold water immersion at knee level does not alter VGRF and whole body stiffness, however mechanical work at ankle joint and total mechanical work of lower extremity are reduced. Cold water immersion at hip level reduces whole body stiffness, VGRF, mechanical work at ankle joint, and total lower extremity mechanical work. Supported by a PSC-CUNY grant (# 66319-00-35)