The contribution of haemoglobin mass to increases in cycling performance induced by simulated LHTL.
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.
Sports Science Sports Medicine, Australian Institute of Sport, PO Box 176, Belconnen, Canberra, ACT, 2616, Australia. laura.garvican@ausport.gov.au
Laura A
LA
Garvican
Torben
T
Pottgiesser
David T
DT
Martin
Yorck Olaf
YO
Schumacher
Martin
M
Barras
Christopher J
CJ
Gore
D000293:Adolescent; D000328:Adult; D000531:Altitude; D054874:Athletic Performance / Q000502:physiology*; D001642:Bicycling / Q000502:physiology; D001810:Blood Volume / Q000502:physiology; D003198:Computer Simulation; D005080:Exercise Test / Q000379:methods*; D005260:Female; D005843:Geography; D006454:Hemoglobins / Q000032:analysis / Q000378:metabolism / Q000502:physiology*; D006801:Humans; D008954:Models, Biological; D009994:Osmolar Concentration; D012111:Residence Characteristics; D055815:Young Adult
D006454:Hemoglobins