Peformance PO or velocity ( Maximal oxygen concumption Peformance VO2 (aerobic) + ventilatory treshold VO2 @ Peformance O2 deficit (anaerobic) ) Total buffering capacity Gross mechanical efficiency Muscle capillary density Stroke volume Maximal heart rate Hemoglobin content Aerobic enzyme activity Figure 1. The physiological factors that determine performance. Adapted from Joyner and Coyle.4 Distribution of PO % Slow twitch (type 1) muscle fibers Anthropometry and elasticity skating in the characteristic low position compared to skating in a more upright position resulted in a greater level of muscle desaturation and the level of muscle desaturation is associated with the increase in blood lactate accumulation.7 So, these results support the general notion that speed skating exercise results in blood flow restriction, which diminishes the contribution of the aerobic energy system and increases the relative contribution of the anaerobic energy systems. Foster and de Koning9 concluded correctly that “the skater is left with the problem of balancing the biomechanical advantage of skating low (longer push, reduced frontal area) with the physiological disadvantage of restricted blood flow to the muscles providing propulsion.” Speed skating performance might therefore benefit from dietary supplements that affect anaerobic energy metabolism, but also gross mechanical efficiency. Hence, the main goal of this review is to summarize dietary supplements that might positively affect anaerobic energy metabolism and gross mechanical efficiency, and to discuss the effects of these dietary supplements on performance. Figure 2. The pre-extension knee angle (θ0 speed skater. Adapted from Noordhof et al.65 ) and trunk angle (θ1 ) of a long-track nummer 3 | november 2015 | Sport & Geneeskunde 7 Pagina 6
Pagina 8Interactieve digitale vakblad, deze vakblad of onderzoeksrapport is levensecht online geplaatst met Online Touch en bied het digitaal zetten van eonderwijscatalogussen.
Sport & Geneeskunde nummer 3 | november 2015 Lees publicatie 52Home