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Sensors (Basel). 2013 Aug 2;13(8):9821-35. doi: 10.3390/s130809821.

Determination of external forces in alpine skiing using a differential global navigation satellite system.

Author information

1
Department of Physical Performance, Norwegian School of Sport Sciences, Oslo 0806, Norway. matthias.gilgien@nih.no

Abstract

In alpine ski racing the relationships between skier kinetics and kinematics and their effect on performance and injury-related aspects are not well understood. There is currently no validated system to determine all external forces simultaneously acting on skiers, particularly under race conditions and throughout entire races. To address the problem, this study proposes and assesses a method for determining skier kinetics with a single lightweight differential global navigation satellite system (dGNSS). The dGNSS kinetic method was compared to a reference system for six skiers and two turns each. The pattern differences obtained between the measurement systems (offset ± SD) were -26 ± 152 N for the ground reaction force, 1 ± 96 N for ski friction and -6 ± 6 N for the air drag force. The differences between turn means were small. The error pattern within the dGNSS kinetic method was highly repeatable and precision was therefore good (SD within system: 63 N ground reaction force, 42 N friction force and 7 N air drag force) allowing instantaneous relative comparisons and identification of discriminative meaningful changes. The method is therefore highly valid in assessing relative differences between skiers in the same turn, as well as turn means between different turns. The system is suitable to measure large capture volumes under race conditions.

PMID:
23917257
PMCID:
PMC3812581
DOI:
10.3390/s130809821
[Indexed for MEDLINE]
Free PMC Article

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