The contribution of haemoglobin mass to increases in cycling performance induced by simulated LHTL

Abstract

We sought to determine whether improved cycling performance following 'Live High-Train Low' (LHTL) occurs if increases in haemoglobin mass (Hb(mass)) are prevented via periodic phlebotomy during hypoxic exposure. Eleven, highly trained, female cyclists completed 26 nights of simulated LHTL (16 h day(-1), 3000 m). Hb(mass) was determined in quadruplicate before LHTL and in duplicate weekly thereafter. After 14 nights, cyclists were pair-matched, based on their Hb(mass) response (ΔHb(mass)) from baseline, to form a response group (Response, n = 5) in which Hb(mass) was free to adapt, and a Clamp group (Clamp, n = 6) in which ΔHb(mass) was negated via weekly phlebotomy. All cyclists were blinded to the blood volume removed. Cycling performance was assessed in duplicate before and after LHTL using a maximal 4-min effort (MMP(4min)) followed by a ride time to exhaustion test at peak power output (T (lim)). VO(2peak) was established during the MMP(4min). Following LHTL, Hb(mass) increased in Response (mean ± SD, 5.5 ± 2.9%). Due to repeated phlebotomy, there was no ΔHb(mass) in Clamp (-0.4 ± 0.6%). VO(2peak) increased in Response (3.5 ± 2.3%) but not in Clamp (0.3 ± 2.6%). MMP(4min) improved in both the groups (Response 4.5 ± 1.1%, Clamp 3.6 ± 1.4%) and was not different between groups (p = 0.58). T (lim) increased only in Response, with Clamp substantially worse than Response (-37.6%; 90% CL -58.9 to -5.0, p = 0.07). Our novel findings, showing an ~4% increase in MMP(4min) despite blocking an ~5% increase in Hb(mass), suggest that accelerated erythropoiesis is not the sole mechanism by which LHTL improves performance. However, increases in Hb(mass) appear to influence the aerobic contribution to high-intensity exercise which may be important for subsequent high-intensity efforts.

“Live high–train low” using normobaric hypoxia: a double-blinded, placebo-controlled study

“…Our findings are in contrast to the results of the initial LHTL study (34) and several follow-up studies, where improvements in VO 2 max (7,16,50,57) or endurance performance (57,59) have been reported. This is intriguing, since we designed the LHTL intervention according to generally accepted recommendations, which for simulated altitude, range from 4 wk at 2,500 -3,000 m (12-16 h/day) (61) to 18 days at 2,500 m (12 h/day) (44).…”

Intravenous Iron Supplementation in Distance Runners with Low or Suboptimal Ferritin

“…Changes in Hb mass induced by accelerated erythropoiesis (as in the case of altitude training, rhEPO use [45]) can be observed in as little as 10 d (14,19), which indicates that a minimum threshold for iron stores must be reached before erythropoiesis is ''switched on.'' The flood of iron into the system via the IV route may therefore be sufficient to activate the erythropoietic system, whereas 6 wk of oral supplementation was not sufficient to reach this threshold.…”

Methods of Monitoring Training Load and Their Relationships to Changes in Fitness and Performance in Competitive Road Cyclists

“…This has previously been shown in a study by Manzi et al 6 with eight recreational long-distance runners. These authors reported that speed at 2 mmol·L Even though internal training load methods such as bTRIMP 10 , Lucia's TRIMP (luTRIMP) 5 and session-RPE (sRPE) 11 and external training load methods such as Training Stress Score™ (TSS) 12 are mentioned in the literature, there is little evidence of a doseresponse relationship between these measures and training outcomes. Other measures of training load such as Edwards' TRIMP (eTRIMP) and iTRIMP have been applied in other sports but not in cycling.…”