INTRODUCTION: It has been established that variations in stride length and associated stride frequency can influence oxygen consumption and energy expenditure during locomotive activities such as running. Whether this effect occurs in cross-country skiing has not been reported. The purpose of this study was to observe the effect of stride frequency Variation on heart rate (HR), oxygen consumption (VO2), and rating of perceived exertion (RPE) during constant velocity treadmill roller-skiing. METHOD: Six female collegiate skiers gave informed consent to participate in the study. Subjects completed an accommodation session consisting of two 15-minute bouts of diagonal-stride treadmill roller-skiing at 107 m*min-1 and 7.0% grade with 10 minute rest between bouts. One week following the accommodation session, each subject completed a testing session involving four 10 minute bouts of diagonal-stride roller-skiing at 107 m-min-1 and 7.0% grade at stride frequencies (SF) of 72, 88, and 96 strides*min-1, and a self-selected (SS) frequency. A calibrated audio metronome was used to establish SF and was verified via video recording at 500 Hz. The order of specific SF bouts followed a Latin Square design and a 10 minute rest was enforced between bouts. HR (Polar XL monitor) and VO2 (SensorMedics 2900z) were measured continuously. Physiological and video data from minutes six through nine for each bout were used in subsequent data analysis. RPE (Borg scale) was obtained from the subject following completion of each bout. Repeated measures ANOVA was employed to determine significant differences among SF (p<.05). RESULTS: Mean data (±s.d.) are presented in Table 1. There were no significant differences in HR, VO2, or RPE among stride frequencies. Self-setected SF for all subjects fell between the forced SF's of 72 and 88 strides*min-1. Highest individual VO2 per subject occurred at various SF with no apparent trend. The lowest mean VO2 occurred at the self-selected SF, although this was not significantly different from VO2 values at other SF's. DISCUSSION: Quadratic relationships in energy cost (and VO2) vs stride frequency have been reported for a number of locomotion activities. Our results indicate no significant effect of varying stride frequency on HR, VO2, or RPE during treadmill roller-skiing. Although the effect on economy is apparent in some activities, if the different stride frequencies are close to the optimal value, the effects are very small. It is possible that this was a factor in this study. CONCLUSION: This study found no significant differences in HR, VO2, and RPE among different stride frequencies during constant velocity treadmill roller-skiing with diagonal stride technique.
© Copyright 2007 4th International Congress on Science and Skiing. Julkaistu Tekijä University of Salzburg. Kaikki oikeudet pidätetään. / Kääntänyt https://www.DeepL.com/Translator