Impact of acute hypoxic exposure on neuromuscular and hemodynamic responses during step intensity dynamic constant external resistance leg extension exercise

• Published in: Journal of electromyography and kinesiology 2024-08, Vol.77, p.102887-102887, Article 102887
• Main Authors: Ugale, Cierra B., Salmon, Owen F., Segovia, Matt D., Smith, Cory M.
• Format: Article
• Language: English
• Subjects: Adult; DCER leg extension; Electromyography; EMG; Hemodynamics - physiology; Humans; Hypoxemia; Hypoxia - physiopathology; Leg - physiology; Male; Muscle Contraction - physiology; Muscle, Skeletal - physiology; Muscle, Skeletal - physiopathology; NIRS; Oxygen Consumption - physiology; Resistance Training - methods; Sympathoexitatory; Young Adult
• ISSN: 1050-6411; 1873-5711
• DOI: 10.1016/j.jelekin.2024.102887

This study examined the effects of acute normoxic and hypoxic exposure on neuromuscular and hemodynamic physiological responses performed during dynamic step muscle actions. Thirteen recreationally active men (mean ± SD age: 21.2 ± 2.9 yrs) performed dynamic leg extensions unilaterally under Normoxic (FiO2 = 21 %) and Hypoxic (FiO2 = 13 %) conditions in a randomized order at 20 %, 40 %, 60 %, 80 %, and 100 % of their maximal strength. Electromyographic (EMG) amplitude, EMG frequency, (Oxygenated and Deoxygenated hemoglobin; OxyHb, DeoxyHb), Total hemoglobin (TotalHb), and skeletal muscle tissue oxygenation status (StO2) were measured from the vastus lateralis during all contractions. There were no detectable differences in the neuromuscular responses between normoxia and hypoxia for EMG amplitude (p = 0.37–0.74) and frequency (p = 0.17–0.83). For EMG amplitude there were general increases with intensity (p