Live high:train low increases muscle buffer capacity and submaximal cycling efficiency

TLDR

The study examined whether hypoxic exposure enhances muscle buffer capacity and exercise efficiency in male athletes. Male athletes underwent a 23‑night live‑high:train‑low protocol (sleeping at 3000 m) while a control group trained at 600 m; VO₂, submaximal cycling, and vastus lateralis biopsies were measured before and after to assess muscle buffering and metabolic responses. After LHTL, muscle buffer capacity rose 18 %, submaximal VO₂ fell 4.4 % and cycling efficiency improved 0.8 %, while VO₂peak declined 7 %, indicating that hypoxia alone boosts buffering and enhances exercise efficiency.

Abstract

This study investigated whether hypoxic exposure increased muscle buffer capacity ( β m) and mechanical efficiency during exercise in male athletes. A control (CON, n =7) and a live high:train low group (LHTL, n =6) trained at near sea level (600 m), with the LHTL group sleeping for 23 nights in simulated moderate altitude (3000 m). Whole body oxygen consumption (V˙ O 2 ) was measured under normoxia before, during and after 23 nights of sleeping in hypoxia, during cycle ergometry comprising 4×4‐min submaximal stages, 2‐min at 5.6 ± 0.4 W kg –1 , and 2‐min ‘all‐out’ to determine total work and V˙ O 2peak . A vastus lateralis muscle biopsy was taken at rest and after a standardized 2‐min 5.6 ± 0.4 W kg –1 bout, before and after LHTL, and analysed for β m and metabolites. After LHTL, β m was increased (18%, P < 0.05). Although work was maintained, V˙ O 2peak fell after LHTL (7%, P < 0.05). Submaximal V˙ O 2 was reduced (4.4%, P < 0.05) and efficiency improved (0.8%, P < 0.05) after LHTL probably because of a shift in fuel utilization. This is the first study to show that hypoxic exposure, per se, increases muscle buffer capacity. Further, reduced V˙ O 2 during normoxic exercise after LHTL suggests that improved exercise efficiency is a fundamental adaptation to LHTL.