Elite endurance runners frequently utilise live high-train high (LHTH) altitude training to improve endurance performance at sea level (SL). Individual variability in response to the hypoxic exposure have resulted in contradictory findings. In the present case study, changes in total haemoglobin mass (tHbmass) and physiological capacity, in response to 4-weeks of LHTH were documented. We tested if a hypoxic sensitivity test (HST) could predict altitude-induced adaptations to LHTH.

Fifteen elite athletes were selected to complete 4-weeks of LHTH (~ 2400 m). Athletes visited the laboratory for preliminary testing (PRE), to determine lactate threshold (LT), lactate turn point (LTP), maximal oxygen uptake VO_2max and tHbmass. During LHTH, athletes completed daily physiological measures [arterial oxygen saturation (SpO₂) and body mass] and subjective wellbeing questions. Testing was repeated, for those who completed the full camp, post-LHTH (POST). Additionally, athletes completed the HST prior to LHTH.

A difference (P < 0.05) was found from PRE to POST in average tHbmass (1.8% ± 3.4%), VO_2max (2.7% ± 3.4%), LT (6.1% ± 4.6%) and LTP (5.4% ± 3.8%), after 4-weeks LHTH. HST revealed a decrease in oxygen saturation at rest (ΔSp_r) and higher hypoxic ventilatory response at rest (HVR_r) predicted individual changes tHbmass. Lower hypoxic cardiac response at rest (HCR_r) and higher HVR_r predicted individual changes VO_2max.

Four weeks of LHTH at ~ 2400 m increased tHbmass and enhanced physiological capacity in elite endurance runners. There was no observed relationship between these changes and baseline characteristics, pre-LHTH serum ferritin levels, or reported incidents of musculoskeletal injury or illness. The HST did however, estimate changes in tHbmass and VO_2max. HST prior to LHTH could allow coaches and practitioners to better inform the acclimatisation strategies and training load application of endurance runners at altitude.