Zinner, C., Wahl, P., Haegele, M., Achtzehn, S., de Marées, M., & Mester, J. (2009). Changes in Hct and Hb in response to HIT and HVT. A paper presented at the 14th Annual Congress of the European College of Sport Science, Oslo, Norway, June 24-27.

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There is a lively discussion about different physiological effects of high-intensity training vs. high-volume training. The effects of these two types of training on blood profiles have not been evaluated. Numerous studies have examined only the response of blood profiles after short term maximal exercise or long-duration exercise.

This study compared the changes of hematocrit, hemoglobin, and plasma volume after a high-intensity training session and a high-volume training session. Male athletes (N = 8) performed two training sessions on a cycle ergometer. The high-intensity training session consisted of four 30-second maximal sprints with five minutes rest in between. During the recovery intervals, Ss remained in a sedentary position on the cycle ergometer. The high-volume training-session consisted of a 60-minute continuous trial at 41–45% of VO2max. Both sessions started with a warm-up of 10 minutes at an intensity of 1.5 Watt/kg bodyweight. Venous blood samples were taken before the warm-up and 10 minutes after the last sprint and after the 60th minute respectively.

Hematocrit values showed no significant differences before both sessions. After the experimental sessions, hematocrit values were significantly increased after high-intensity training but not after high-volume training. Significant changes in hemoglobin values were also found only after high-intensity training. Plasma volumes after the two interventions were significantly higher after high-intensity training when compared to high-volume training.

The small shift of hematocrit, hemoglobin, and plasma volume after high-volume training could be explained by water loss (sweat) during long duration exercise, but during the high-intensity training session water loss due to sweat is inconsequential. The shift of plasma volume, hematocrit, and hemoglobin after high-intensity training is likely a result of an increased plasma osmotic pressure and local capillary hydrostatic pressure. During high-volume training sessions, hemodynamic forces are considerably lower than during the high-intensity training sessions.

Implication. WADA has defined upper limits for hematocrit and hemoglobin concentrations supposedly to reduce the likelihood of blood manipulations. This is an example of WADA's erroneous "one-size-fits-all" assumption that single physiological values should be applied to all athletes. This study showed considerable and significant variations in blood factors that are related to the type of training experienced. As well, individual variations need to be considered. The current WADA rules do not yield fair competition parameters but rather unfairly treat some individuals purely by ignoring training experiences and personal physiological characteristics. Test results for these factors may solely depend on when testing is done and the most recent type of training completed. That is not a fair or scientific application.

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