Les effets du préconditionnement métabolique sur l'oxygénation musculaire et sur la performance en patinage de vitesse longue piste
|Authors:||Richard, Philippe T.|
|Abstract:||The speed-skating position leads to blood-flow restriction and deoxygenation in the lower limbs that may enhance the metabolic processes associated with fatigue, thereby affecting technique and performance. Highlevel athletes use several metabolic conditioning strategies to optimize their physiological responses and performances. Despite their potential impact on muscle oxygenation noted in many sports, no data is available regarding the impact of such techniques on long-track speed skating performance. The peculiar histologic muscular characteristics associated with the skaters of different energetic profile and skating specialties may influence the response to conditioning stimulus and therefore, the purpose of our studies was to assess the specific on-ice impact of conditioning strategies with respect to the energetic profile of the skaters. Remote ischemic preconditioning (RIPC) has been found to enhance performance in different contexts, improve vascular function and muscular perfusion (locally and systemically) and to optimize mitochondrial efficiency. In study 1, we found that RIPC has no practical ergogenic impact on 1000-m long-track speed-skating performance in elite athletes and that this technique tends to increase muscle oxygen extraction in sprint athletes. This could increase the metabolic stress in training in this type of athlete and thus, optimize the chronic adaptations. Respiratory muscle fatigue might increase sympathetic vasoconstrictor outflow to working skeletal muscles through a respiratory muscle metaboreflex, thus reducing limbs blood flow and accelerating the development of exercise-induced locomotor muscle fatigue. An inspiratory muscle warm-up (IMW) may reduce inspiratory muscle fatigue and attenuate locomotor muscle deoxygenation during maximal exercises. In study 2, we found that a standard IMW protocol provides no meaningful effect on blood volume and performance in elite speed skaters. Finally, elite athletes in varied sports typically combine ergogenic strategies in the hope of taking advantage of multiple strategies simultaneously in order to enhance physiological responses and competitive performance. However, the scientific evidence for such practices is very scarce. Results of study 3 indicate that combining RIPC (chronic) and IMW has no practical ergogenic impact on 600-m speed-skating performance in elite skaters. Summing up, the results of these three studies highlight the low variability of physiological responses and performance in elite athletes as well as the singularities associated with the position of speed skaters; neither ischemic preconditioning, nor an inspiratory muscles warm-up, nor the combination of these two strategies has improved performance in elite skaters and only minor changes in muscular oxygenation were observed. The very high level of aerobic fitness of the athlete, the practice of a thorough warm-up protocol and the extremely low position may have contributed to lessen the effectiveness of these techniques.|
|Document Type:||Thèse de doctorat|
|Open Access Date:||21 December 2018|
|Collection:||Thèses et mémoires|
All documents in CorpusUL are protected by Copyright Act of Canada.