Rebuttal to the Con Statement

I congratulate Dr. Jacobs on his con position statement regarding the efficacy of LHTL, and appreciate the opportunity to respond to the points raised in his article. The position he takes is based on three assumptions that he indicates are “inherent to the LHTL postulate.” First, the argument is made that several hypoxia-induced physiological responses “threaten sea-level performance.” In doing so, no mention is made of the physiologically-significant and consistent benefit of increased total hemoglobin mass (∼2%) resulting from an effective dose of LHTL (Garvican et al., 2011; Levine and Stray-Gundersen, 1997; 2005), which overrides any minor detrimental effects, such as sleep disturbances (Pedlar et al., 2005), on sea level performance. Second, the argument is made that the “train low” aspect of LHTL does not necessarily mitigate the limiting effects of hypoxia on training capabilities (e.g., running velocity). In response, it has been objectively quantified that a high-intensity interval workout at 1250 m (“train low”) was done at a running velocity that was 8% faster versus 2500 m (“train high”) (Levine and Stray-Gundersen, 1997). By extension, it is logical to assume that a greater training stimulus (greater “oxygen flux”) was accrued by the “train low” athletes, an effect that was ultimately borne out by their improved sea level 5000 m run performance a few weeks later (Levine and Stray-Gundersen, 1997). Third, the argument is made that LHTL does not appear to be an effective training strategy for increasing total hemoglobin mass in elite athletes, indicating that elites are “a population with an already elevated total hemoglobin mass” (Robach and Lundby, 2012). One could counter-argue that: (a) not all elite athletes present with relatively high total hemoglobin mass levels, and therefore could benefit from some form of LHTL; (b) among those elite athletes who do present with relatively high total hemoglobin mass, perhaps a more-sustained dose of hypoxia is necessary to affect erythropoiesis, one requiring near full-time residence at altitude; and (c) among those athletes who do present with relatively high total hemoglobin mass, perhaps LHTL using hypobaric hypoxia versus normobaric hypoxia (nitrogen dilution) is required to attain a sufficient erythropoietic stimulus (Millet and Pialoux, 2012). Indeed, several studies involving National Team athletes (versus controls) have shown a significant increase in total hemoglobin mass as a result of LHTL (Garvican et al., 2011; Wehrlin et al., 2006; Wilber 2007). Finally, the argument is made by Dr. Jacobs that LHTL does not improve sea level performance. This argument is based on the placebo-controlled, double-blind study of Siebenmann et al. (2012), which failed to demonstrate improvements in total hemoglobin mass and, subsequently, on post LHTL cycling performance in elite athletes. However, the validity of the conclusions of Siebenmann et al. (2012) can be questioned based on the following: (a) 50% of the subjects actually demonstrated an increase in total hemoglobin mass, whereas 20% fell within TEM, resulting in only 30% who did not show an unequivocal increase; (b) the 2-week baseline lead-in was conducted at 1135 m (Premanon), which is relatively high versus previous LHTL studies that conducted lead-in phases at approximate sea level (Garvican et al. 2011; Levine and Stray-Gundersen, 1997) and therefore, may have confounded the results; (c) the control group alternated between simulated sea level (16 h/day) and a natural altitude of 1135 m (8 h/day); this discontinuous “sea level” environment may have affected the results; and (d) there is criticism that the training load of the LHTL group was more intense versus the control group, resulting in greater residual fatigue post-altitude, which may have had a negative effect on subsequent sea level cycling performance (Schmitt and Millet, 2012). In summary, the con position regarding LHTL attempted to show that several assumptions regarding the positive effects of LHTL on sea level performance “are either unsubstantiated or prove invalid.” It is not apparent that this was done to a convincing level, based on the points raised in this rebuttal. Again, I congratulate Dr. Jacobs on his valuable and ongoing contributions to the advancement of knowledge in the area of hypoxia/altitude training, and I appreciate the opportunity to engage him in this pro/con forum.