PRESSURE DISTRIBUTION IN INLINE SKATING STRAIGHTS WITH DIFFERENT SPEEDS

Abstract

Introduction: Inline skating (ILS) has been one of the fastest growing sports in recent years. Most literature deals with injuries and the physiological responses of ILS. Recently some authors have published work that is related to biomechanics and ILS (Mahar et al., 1997; Giacobetti et al., 1997). However, from a biomechanical point of view little is known about ILS. The purpose of this study was to quantify plantar pressure distribution and determine basic stride characteristics for two skating velocities. Methods: Thirteen male advanced skaters with shoe size 9 participated in the study. Their mean age, mass and height were 30.3±7 years, 71.9±4.5 kg, 175±5 cm, respectively. The Pedar Mobile system was used to collect plantar pressure information. A recreation skate was fitted with a rigid, flat insole to eliminate the influence of the sock liner. Testing took place at an indoor hockey rink and data was collected during the straights. The two skating velocities, 18 km/h and 24 km/h, were controlled by two timing lights, and all trials exceeding 5% of the exact speed were excluded. Nine trials per foot were saved for analysis. Peak pressure (PP), time to PP (tPP), and impulse were calculated using Novel-win software. Times of the single and double support phases were also extracted. Results: Three areas of high pressure, heel (H), first metatarsal head (FMH), first toe (FT) were identified. No differences were found between left and right foot. Peak pressure (PP), time of PP (tPP) and impulse (I) were derived for these areas and are presented below. [...] Conclusions: PP measured in this study are comparable to those reported during walking, but lower than those during running. The lower impulse with increasing speed is due to the decreased contact time per stride. The differences in tPP at FMH and FT are also the result of the change in contact time. This is indicative of a longer glide phase and a later push-off at slow speed. Assuming similar skate orientation, the reduced impulse at a faster speed suggests that stride frequency is the dominant factor responsible for velocity. De Boer/ Nilsen (1989) reported similar observations for Olympic speed skaters.