The influence of a rocking-motion device built into classic cross-country roller-ski bindings on biomechanical, physiological and performance outcomes

Abstract

This study aimed to determine whether the recently developed Flow Motion Technology® roller-ski prototype could improve indicators of performance during sub-maximal and maximal cross-country roller skiing. Thirteen national and international cross-country skiers completed 2 experimental trials: 1 with Flow Motion Technology® activated, allowing a rocking motion between the foot and ski binding, and 1 with the foot fixed in a traditional manner. Each trial included 2 sub-maximal bouts using the diagonal-stride and double-poling sub-techniques, as well as a double-poling maximal velocity test and a diagonal-stride 6-min time trial. There were no differences in performance between Flow Motion Technology® and traditional roller skiing during the maximal velocity test or the time trial. However, reductions in mean plantar force during sub-maximal diagonal stride (p = 0.011) and ankle range of motion during sub-maximal (p = 0.010) and maximal (p = 0.041) diagonal stride were observed with Flow Motion Technology® versus traditional roller skiing. This, together with a reduced minimum horizontal distance of the hips in front of the ankles during sub-maximal double poling (p = 0.001), indicated impaired technique with Flow Motion Technology®, which may have contributed to the trend for reduced gross efficiency during double poling with Flow Motion Technology® (pη2 = 0.214). Significant physiological differences included a reduced sub-maximal double poling respiratory exchange ratio (p = 0.03) and a greater maximal heart rate during the time trial (p = 0.014) with Flow Motion Technology®. We conclude that the application of Flow Motion Technology® requires further examination before use in training and competition.