Acute physiological and perceptual responses to high‐load resistance exercise in hypoxia

Abstract

This study assessed whether hypoxia during high-load resistance exercise could enhance the acute physiological responses related to muscular development. Twelve trained men performed exercise in three conditions: normoxia (fraction of inspired oxygen [F O ] = 21%), moderate-level hypoxia (F O = 16%) and high-level hypoxia (F O = 13%). Exercise comprised high-load squats and deadlifts (5 × 5 using 80% of 1-repetition maximum with 180-s rest). Muscle oxygenation and activation were monitored during exercise. Metabolic stress was estimated via capillary blood sampling. Perceived fatigue and soreness were also quantified following exercise. While the hypoxic conditions appeared to affect muscle oxygenation, significant differences between conditions were only noted for maximal deoxyhaemoglobin in the deadlift (P = 0·009). Blood lactate concentration increased from 1·1 to 1·2 mmol l at baseline to 9·5-9·8 mmol l after squats and 10·4-10·5 mmol l after deadlifts (P≤0·001), although there were no between-condition differences. Perceived fatigue and muscle soreness were significantly elevated immediately and at 24 h following exercise, respectively, by similar magnitudes in all conditions (P≤0·001). Muscle activation did not differ between conditions. While metabolic stress is thought to moderate muscle activation and subsequent muscular development during hypoxic resistance training, it is not augmented during traditional high-load exercise. This may be explained by the low number of repetitions performed and the long interset rest periods employed during this training. These findings suggest that high-load resistance training might not benefit from additional hypoxia as has been shown for low- and moderate-load training.

Intermittent Resistance Training at Moderate Altitude: Effects on the Force-Velocity Relationship, Isometric Strength and Muscle Architecture

“…Despite greater acute hormonal and metabolic stress responses following resistance exercise under hypoxic conditions (Kon et al, 2010 ; Kurobe et al, 2015 ), there are studies reporting both significant (Nishimura et al, 2010 ; Manimmanakorn et al, 2013b ; Kurobe et al, 2015 ) and no meaningful effects (Friedmann et al, 2003 ; Ho et al, 2014 ; Kon et al, 2014 ) of IHRT on the muscle cross-sectional area (CSA). Although differences in crucial resistance-training methodological aspects, such as the resting time between training sets, may influence the lack of agreement between IHRT studies reporting changes in muscle CSA (Scott et al, 2017a , b ), other constraints in the current literature also limit the translation of these findings to the field. Resistance training practices aiming to enhance athletic performance often comprise maximal intended explosive efforts leading to both training-specific structural (Blazevich et al, 2003 ) and neural adaptations (Buckthorpe et al, 2015 ).…”

“…Acute exposures to moderate hypobaric (i.e., terrestrial moderate hypoxia), but not normobaric hypoxia (Feriche et al, 2014 ; Scott et al, 2014a , 2017a , b ), have been described to enhance muscle performance during the bench-press (Feriche et al, 2014 ) and squat jump exercises (García-Ramos et al, 2016 ). Although the underlying mechanisms are unclear, these findings suggest that IHRT under hypobaric conditions could lead to positive neuromuscular adaptations.…”

Electromyography: A Simple and Accessible Tool to Assess Physical Performance and Health during Hypoxia Training. A Systematic Review

“…Reasons for exclusions after full-text review were unrelated outcomes (n = 1), unsuitable methodology (n = 1), lack of control group (n = 5), inappropriate intervention (n = 10), and study design (n = 5). The remaining nine [15][16][17][18][19][20][21][22][23] studies met our inclusion criteria and were included in the present systematic review (Figure 1).…”

“…The characteristics of the studies included in the systematic review appear in Table 3. Squat exercise plan [16,17] Exercises of submaximum extension of the knee [18] Sprints [22] Exercises of voluntary isometric contraction [23] Muscular activity…”

“…Integrated electromyography (iEMG) [16][17][18] Surface electromyography (sEMG) [16][17][18] Muscle fatigue (exhaustion time)…”