Shock attenuation (SA) has been well studied in activities such as walking and running (Chu, et al. 2004; Derrick, et al. 2004; Mercer, et al. 2003); however, there is a lack of research regarding SA during landing. Furthermore, there is lack of information regarding which structures attenuate shock. The purpose of this study was to examine SA among the leg-hip, hip-head, and leg-head segments during landing. Each subject (n=10, Age 26.3 +/- 2.71 years, Height 1.68 +/- 0.08 m, Mass 70.49 +/- 16.03 kg) was instrumented with accelerometers at the leg, hip and forehead. Subjects then performed landings from three heights: 30cm, 60cm, and 90cm. For each height, subjects completed 5 landing trials. Rest was provided between each trial. Order of conditions was randomized to account for fatigue and learning. During each landing, accelerations were recorded at 1000 Hz for the leg, hip, and head respectively using light-weight accelerometers. Data were reduced by identifying the peak impact accelerations for the leg (PkLeg), hip (PkHip), and head (PkHead). After peak impact accelerations were identified, SA was calculated for three locations using the following formulas: Total (between leg and head) = [1-PkHd/PkLeg]*100, Lower (between leg and hip) = [1-PkHip/PkLeg]*100, Upper (between hip and head) = [1-PkHd/PkHip]*100. Peak impact accelerations as well as SA were the dependent variables. There were three levels of independent variable height (30 cm, 60 cm, and 90 cm) and location (leg, hip, and head for peak impact accelerations; total, lower, and upper-body for SA). Variables were compared using repeated measures ANOVA (&agr;=0.05). It was determined that there was an interaction between height and location for peak impact acceleration (p<0.05) but not for SA (p>0.05). Peak impact accelerations across all locations increased with an increase in height (p<0.05). It was also determined that total and lower body SA increased with an increase in height (p<0.05 ) but upper-body SA did not (p>0.05) With an overall increase in peak impact accelerations at all locations, and an increase in total and lower-body SA, but not upper-body SA, it appears the lower extremity is primarily responsible for the attenuation of the impacts resulting from landing.
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