Inadequate UA dilator muscle function may play an important role in the pathophysiology of obstructive sleep apnea (OSA). To date, tongue mechanical properties have been mainly assessed using protrusion protocol with conflicting results, while performance during elevation task among patients with OSA remains unknown. This study was aimed to assess tongue muscle strength, strength stability, endurance time, fatigue indices and muscle total work, using elevation and protrusion tasks with repetitive isometric fatiguing contractions during awake in 12 normal+mild, 17 moderate and 11 severe patients with OSA, and to assess the influence of BMI and age. Endurance time was longer in protrusion than elevation task (p=0.01). In both tasks, endurance time was negatively correlated with baseline value of strength coefficient of variation (p<0.01). Compared to other groups, patients with moderate OSA had the lowest muscle total work for protrusion (p=0.01) and shortest endurance time (p=0.04) regardless of type of task. Additionally, in patients with moderate-severe OSA, the muscle total work for both tasks was lower in non-obese compared to obese (p<0.05). Muscle total work for protrusion was positively correlated with AHI in obese subjects (p<0.01). Endurance time was shorter (p<0.01) and recovery time was longer (p=0.02) in the old compared to young subjects. In conclusion, tongue is more prone to fatigue during elevation task and in patients with moderate OSA. Obesity appeared to prevent alteration of tongue mechanical properties in patients with OSA. Baseline strength stability may predict endurance, illustrating the role of central neuromuscular output in tongue resistance to fatigue.
- Obstructive sleep apnea
- upper airway muscle
- Copyright © 2016, Journal of Applied Physiology