TY - JOUR
T1 - High-Altitude Acclimatization Improves Recovery from Muscle Fatigue
AU - Ruggiero, Luca
AU - Hoiland, Ryan L.
AU - Hansen, Alexander B.
AU - Ainslie, Philip N.
AU - Mcneil, Chris J.
PY - 2019/7/31
Y1 - 2019/7/31
N2 - Purpose: We investigated the effect of high-altitude acclimatization on peripheral fatigue compared to sea level and acute hypoxia.
Methods: At sea level (350 m), acute hypoxia (environmental chamber), and chronic hypoxia (5050 m, 5-9 days) (partial pressure of inspired oxygen = 140, 74 and 76 mmHg, respectively), 12 participants (11 in chronic hypoxia) had the quadriceps of their dominant leg fatigued by 3 bouts of 75 intermittent electrically-evoked contractions (12 pulses at 15 Hz, 1.6 s between train onsets, and 15 s between bouts). The initial peak force was ~30% of maximal voluntary force. Recovery was assessed by single trains at 1, 2, and 3 min post-protocol. Tissue oxygenation of rectus femoris was recorded by near-infrared spectroscopy.
Results: At the end of the fatigue protocol, the impairments of peak force and peak rates of force development and relaxation were greater (all P < 0.05) in acute hypoxia (~51, 53 and 64%,
respectively) than sea level (~43, 43 and 52%) and chronic hypoxia (~38, 35 and 48%). Peak force and rate of force development recovered faster (P < 0.05) in chronic hypoxia (pooled data
for 1-3 min: ~84 and 74% baseline, respectively) compared to sea level (~73 and 63% baseline) and acute hypoxia (~70 and 55% baseline). Tissue oxygenation did not differ among conditions
for fatigue or recovery ( ACCEPTED P > 0.05).
Conclusion: Muscle adaptations occurring with chronic hypoxia, independent of other adaptations, positively influence muscle contractility during and after repeated contractions at high altitude.
AB - Purpose: We investigated the effect of high-altitude acclimatization on peripheral fatigue compared to sea level and acute hypoxia.
Methods: At sea level (350 m), acute hypoxia (environmental chamber), and chronic hypoxia (5050 m, 5-9 days) (partial pressure of inspired oxygen = 140, 74 and 76 mmHg, respectively), 12 participants (11 in chronic hypoxia) had the quadriceps of their dominant leg fatigued by 3 bouts of 75 intermittent electrically-evoked contractions (12 pulses at 15 Hz, 1.6 s between train onsets, and 15 s between bouts). The initial peak force was ~30% of maximal voluntary force. Recovery was assessed by single trains at 1, 2, and 3 min post-protocol. Tissue oxygenation of rectus femoris was recorded by near-infrared spectroscopy.
Results: At the end of the fatigue protocol, the impairments of peak force and peak rates of force development and relaxation were greater (all P < 0.05) in acute hypoxia (~51, 53 and 64%,
respectively) than sea level (~43, 43 and 52%) and chronic hypoxia (~38, 35 and 48%). Peak force and rate of force development recovered faster (P < 0.05) in chronic hypoxia (pooled data
for 1-3 min: ~84 and 74% baseline, respectively) compared to sea level (~73 and 63% baseline) and acute hypoxia (~70 and 55% baseline). Tissue oxygenation did not differ among conditions
for fatigue or recovery ( ACCEPTED P > 0.05).
Conclusion: Muscle adaptations occurring with chronic hypoxia, independent of other adaptations, positively influence muscle contractility during and after repeated contractions at high altitude.
KW - electrical stimulation
KW - high altitude
KW - muscle contractility
KW - peripheral fatigue
U2 - 10.1249/MSS.0000000000002100
DO - 10.1249/MSS.0000000000002100
M3 - Article
C2 - 31343519
SN - 0195-9131
JO - Medicine and Science in Sports and Exercise
JF - Medicine and Science in Sports and Exercise
ER -