INTRODUCTION: In sit-skiing, impaired athletes are classified into five classes based on the evaluations of their trunk control (LW10, LW10.5, LW11, LW11.5, LW12). A calculation system in which certain percentages are deducted of the competition finishing time (14.0%, 10.0%, 6.0%, 4.0%, 0.0%) has been created. [1] Two commonly used sitting positions are "kneeing" (KL) and "knee-high" (KH) positions [2]. Studies on biomechanical patterns and performance between classified athletes have mostly been conducted under laboratory conditions and have reported many positive patterns of KL for sit-skiing performance. [2,] In the ski ergometer, the effect of chancing sitting position in able-bodied athletes on performance in physiological and biomechanical parameters has been reported to be 7-15% favoring KL position [3]. The purpose of the present study wanted to measure the effect of sitting position on sit-skiing performance on a treadmill because it could simulate natural conditions better than in the ski ergometer. METHODS: The athlete was LW11 classified female sit-skier, who had used KH position ten years, before one year of training in the KL position. In the ski ergometer, the athlete performed a maximal power test and on a treadmill, a maximal oxygen uptake test and performance tests for speed and uphill till exhaustion. Cycle length (CL), cycle time (CT), cycle rate (CR) and Blood lactate (B-La) were measured from treadmill tests. Maximal oxygen uptake VO2peak (ml/kg/min), oxygen consumption (VO2, l/min) and ventilation (VE, l/min) were measured during maximal oxygen uptake test. RESULTS/DISCUSSION: 7.0%, 6.0% and 5.4% greater time to exhaustion in treadmill tests (maximal oxygen uptake test, speed test & uphill test respectively) and 14.4% higher power output in the ski ergometer in the KL position were observed. Higher CL and CT with lower CR were recorded in the KL position. The greatest difference in lactate (B-La peak) was after the maximal test; 42,5% higher in the KL than in the KH position. There were no differences in VO2 peak, Ventilation was 6.0% higher in KH than in KL. A study with abled-bodied athletes reported the differences between the sitting positions to be 7-15% in the ski ergometer in physiological and biomechanical patterns [3], which is in line with the present study. The differences between the positons increase when the load increases and are caused by better ability to use upper body in the KL position. [2;3] The differences between the positions are greater than the differences between the classes. CONCLUSION: Based on the findings of previous studies and this case study, it is highly recommended for the athletes to use KL position in sit-skiing. Unfortunately using KL position is not possible in lower classes (LW 10, LW10.5 and mostly LW11) due to their impairments and control of trunk abilities.
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