GENERAL PHYSIOLOGICAL MEASURES DO NOT PREDICT PERFORMANCE IN ELITE RUNNERS
Ferri, A., Adamo, S., La Torre, A., Marzorati, M., Danzi, S., & Miserocchi, G. (2009). Peculiarity of the O2 delivery – O2 utilization system in middle distance runners: Correlation with performance. A paper presented at the 14th Annual Congress of the European College of Sport Science, Oslo, Norway, June 24-27.
"Many studies conducted since the 1970s have investigated the particular physiologic characteristics of middle-distance athletes. Several authors have focused on physiological parameters, such as maximal oxygen consumption, VO2max, and velocity at VO2max (Vmax), that may determine/predict performance. However, at the moment there is no consensus."
This study investigated additional physiological parameters (VO2 kinetics, maximal capacity of muscle O2 extraction, presence of a slow component of VO2 and Delta[deoxy(Hb+Mb)], lactate concentration, time to exhaustion) that may better predict performance in an homogeneous group of international level middle-distance (1,500 m) runners (N = 8). After an incremental exercise to voluntary exhaustion on a treadmill to evaluate peak VO2 and the ventilatory threshold, Ss carried out two, six-minute, constant-load exercise tests below the ventilatory threshold and two constant-load exercises to exhaustion at the maximal velocity reached during the incremental exercise. Tests were performed on three different days. Pulmonary VO2, VCO2 and ventilation were determined breath-by-breath. Vastus lateralis oxygenation was determined by near-infrared spectroscopy and changes in deoxygenated hemoglobin + myoglobin concentration Delta[deoxy(Hb+Mb)] were taken as a muscle oxygenation index. To evaluate blood lactate concentration, a blood sample from an ear lobe was also taken at baseline and at the end of each exercise.
In contrast to previous research, there was no significant correlation between VO2peak or Vmax and 1,500 m velocity. The only parameters that were significantly correlated with the 1,500 m velocity were the maximal capacity of O2 extraction (r = 0.78) and the amplitude of the slow component of Delta[deoxy(Hb+Mb)] (r = 0.74). All other parameters measured were not correlated with 1500-m performance.
Implication. In high-level 1,500 m runners, the best predictors of 1,500 m velocity were related to the capacity of the muscle to extract O2, a peripheral parameter which reflects the muscle’s capacity for oxidative metabolism (dependent on the number and quality of mitochondria, capillarization, etc.). ["The relationship between the slow component of Delta[deoxy(Hb+Mb)] and 1500-m velocity can possibly be attributed to the Bohr effect, that is, a greater increase in lactate by the better performing athletes may provoke a greater release of O2 from the hemoglobin and a subsequent improved aerobic efficiency of the muscle. Further research is required to better understand how to improve the capacity of the muscle to extract O2."]
[It should be noted that the subject pool was homogeneous in performance preference and so correlations with general parameters would be hard to obtain. If this study were repeated with subjects of varied preferences, correlations would very likely be higher. However, when handling elite athletes, general physiological factors and measures are relatively meaningless for understanding training effects and predicting performances.
The principal broader implication of this work is that performance is governed by the capacity of peripheral mechanisms, that is, the characteristics of the muscles determine performance capacities. No matter how many red blood cells, the amount of EPO, the saturation level of oxygen transported in the blood, etc., when the extraction capacity of the muscles is maximum, the remainder is excess and flows on with the blood. If the muscle capacity were not the limiting factor, then there would be less variation in performance capabilities across the species. ]
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