Neuromuscular evaluation of arm-cycling repeated sprints under hypoxia and/or blood flow restriction
This study aimed to determine the effects of hypoxia and/or blood flow restriction (BFR) on an arm-cycling repeated sprint ability test (aRSA) and its impact on elbow flexor neuromuscular function.
Fourteen volunteers performed an aRSA (10 s sprint/20 s recovery) to exhaustion in four randomized conditions: normoxia (NOR), normoxia plus BFR (NBFR), hypoxia (FiO2 = 0.13, HYP) and hypoxia plus BFR (HBFR). Maximal voluntary contraction (MVC), resting twitch force (Db10), and electromyographic responses from the elbow flexors [biceps brachii (BB)] to electrical and transcranial magnetic stimulation were obtained to assess neuromuscular function. Main effects of hypoxia, BFR, and interaction were analyzed on delta values from pre- to post-exercise.
BFR and hypoxia decreased the number of sprints during aRSA with no significant cumulative effect (NOR 16 ± 8; NBFR 12 ± 4; HYP 10 ± 3 and HBFR 8 ± 3; P < 0.01). MVC decrease from pre- to post-exercise was comparable whatever the condition. M-wave amplitude (− 9.4 ± 1.9% vs. + 0.8 ± 2.0%, P < 0.01) and Db10 force (− 41.8 ± 4.7% vs. − 27.9 ± 4.5%, P < 0.01) were more altered after aRSA with BFR compared to without BFR. The exercise-induced increase in corticospinal excitability was significantly lower in hypoxic vs. normoxic conditions (e.g., BB motor evoked potential at 75% of MVC: − 2.4 ± 4.2% vs. + 16.0 ± 5.9%, respectively, P = 0.03).
BFR and hypoxia led to comparable aRSA performance impairments but with distinct fatigue etiology. BFR impaired the muscle excitation–contraction coupling whereas hypoxia predominantly affected corticospinal excitability indicating incapacity of the corticospinal pathway to adapt to fatigue as in normoxia.
KeywordsCorticospinal excitability Transcranial magnetic stimulation Occlusion Neuromuscular fatigue BFR
Active motor threshold
Analysis of variance
Repeated arm-cycling sprint ability test
Blood flow restriction
Cervicomedullary motor evoked potential
Cortical silent period
Electrical muscle stimulation
Electrical nerve stimulation
Estimated resting twitch
Electronic supplementary material
Fraction of inspired oxygen
Hypoxia with BFR
Motor evoked potential
Amplitude of the muscle compound action potential
Messenger ribonucleic acid
Amplitude of the muscle compound action potential during maximal voluntary contraction
Maximal voluntary contraction
Muscle compound action potential
Normoxia with blood flow restriction
Neuromuscular function evaluation
After repeated arm-cycling sprint ability test
Before repeated arm-cycling sprint ability test
Root mean square
Repeated sprint ability
Short-interval intracortical inhibition
Peripheral arterial oxygen saturation
Transcranial magnetic stimulation
Tissue saturation index
Time to exhaustion
Voluntary activation assessed with TMS
Special thanks are given to the participants for their dedication, commitment, and cooperation with this study and to Naiandra Dittrich for her assistance during experimental set up and data acquisition.
GPM, FB, NP, and TR designed the study methodology. AP and SW collected the data and analyzed the results. AP, SW, and TR drafted the article. All authors reviewed and revised the work. All authors reviewed the final article and approved it for submission.
Funding was provided by University Savoie Mont Blanc and the French Conseil Savoie Mont Blanc.
Compliance with ethical standards
Conflict of interest
AP was supported by a doctoral research grant from University Savoie Mont Blanc and the French Conseil Savoie Mont Blanc. The authors declare that they have no conflict of interest.
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