Key result
Acute exposure to moderate real altitude did not significantly alter motoneuron pool excitability compared to low altitude, but it significantly increased drop jump height after 6 hours of exposure (ES 0.41).
Why the study?
To test whether ascending to a moderate real altitude affects resting motoneuron pool excitability and whether any alteration is reflected in squat jump and drop jump muscle actions.
Does acute exposure to moderate real altitude improve motoneuron pool excitability and jumping performance in participants?
RCT (n=15)
Open-label
Randomized and counterbalanced order
No
Does acute exposure to moderate real altitude improve motoneuron pool excitability and jumping performance in participants?
Acute exposure to moderate altitude may enhance drop jump performance after several hours, though effects on motoneuron pool excitability remain inconclusive.
Acute altitude exposure shows transient H-reflex changes without confirmed between-condition effects; leaves open neuromuscular impacts on explosive performance.
The aim of the study was to test whether ascending to a moderate real altitude affects motoneuron pool excitability at rest, as expressed by a change in the H-reflex amplitude, and also to elucidate whether a possible alteration in the motoneuron pool excitability could be reflected in the execution of lower-body concentric explosive (squat jump; SJ) and fast eccentric-concentric (drop jump; DJ) muscle actions. Fifteen participants performed four experimental sessions that consisted of the combination of two real altitude conditions [low altitude (low altitude, 690 m), high altitude (higher altitude, 2,320 m)] and two testing procedures (H-reflex and vertical jumps). Participants were tested on each testing day at 8, 11, 14 and 17 h. The only significant difference ( p < 0.05) detected for the H-reflex was the higher H-reflex response (25.6%) obtained 15 min after arrival at altitude compared to baseline measurement. In terms of motor behavior, DJ height was the only variable that showed a significant interaction between altitude conditions (LA and HA) and time of measurement (8, 11, 14 and 17 h) as DJ height increased more during successive measurements at HA compared to LA. The only significant difference between the LA and HA conditions was observed for DJ height at 17 h which was higher for the HA condition ( p = 0.04, ES = 0.41). Although an increased H-reflex response was detected after a brief (15–20 min) exposure to real altitude, the effect on motorneuron pool excitability could not be confirmed since no significant changes in the H-reflex were detected when comparing LA and HA. On the other hand, the positive effect of altitude on DJ performance was accentuated after 6 h of exposure.
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Štirn et al. (2022) conducted an RCT in Healthy and physically active (n=15). Acute exposure to moderate real altitude vs. Low altitude (690 m above sea level) was evaluated on Drop jump (DJ) height at 17 h (after 6 hours of exposure) (ES 0.41, p=0.04). Acute exposure to moderate real altitude did not significantly alter motoneuron pool excitability compared to low altitude, but it significantly increased drop jump height after 6 hours of exposure (ES 0.41).
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