Aspects of Respiratory Muscle Fatigue in a Mountain Ultramarathon Race

Abstract

Ultraendurance running reduces respiratory muscle strength for inspiratory muscles shown to result from significant peripheral muscle fatigue with only little contribution of central fatigue. This is in contrast to findings in locomotor muscles. Whether this difference between muscle groups results from inherent neuromuscular differences, their specific pattern of loading or other reasons remain to be clarified.

Thoraco-abdominal coordination and performance during uphill running at altitude

“…In particular, during a 2.5-hour treadmill run, simulating a marathon, a reduction in vital capacity of approximately 3% was reported after at least 90 min, while an average 8.6% reduction in post-race vital capacity was found after a marathon [46]. A similar reduction of approximately 10% was recently reported after an ultramarathon [3,7, 49]. In our study we observed a small but significant 4% reduction in vital capacity after an uphill and downhill run with an average duration of 95 min.…”

“…Studies on uphill running and mountain ultramarathons have considered biomechanical and neuromuscular adaptations [41,42] as well as respiratory modifications [3,7]. To the best of our knowledge, no study has investigated ventilation and ventilatory pattern during the run.…”

“…High-intensity exercise under these environmental conditions requires extensive respiratory and cardiovascular system engagement. The respiratory and cardiac responses that occur during this type of exercise represent key constituents of endurance performance that can be affected by oxygen desaturation and increased respiratory work [1–3]. Indeed, during high-intensity exercise at altitude, ventilatory demands increase due to the combined effects of exercise and hypoxia, which affect the ventilatory system above 2000–2500 m [4–6].…”

“…Indeed, during high-intensity exercise at altitude, ventilatory demands increase due to the combined effects of exercise and hypoxia, which affect the ventilatory system above 2000–2500 m [4–6]. Under such conditions, the respiratory muscles become strained and can experience progressive fatigue, and lung function can be impaired [3,7]. The postural tasks related to the presence of steep slopes and different types of terrain [8] may also affect the ventilatory system through modifications of thoraco-abdominal coordination, which involves the coordinated action of the diaphragm and the abdominal muscles to inflate and deflate the chest.…”

Respiratory Effects of Thoracic Load Carriage Exercise and Inspiratory Muscle Training as a Strategy to Optimize Respiratory Muscle Performance with Load Carriage

“…Diaphragm fatigue is considered present with a post-exercise decline in P di, tw ≥ 15% [109]. Due to the invasive nature of esophageal balloon-tipped catheters, recent efforts have aimed to assess non-volitional declines in mouth pressure in response to cervical magnetic stimulation of the phrenic nerve [56, 119, 120], which were shown to be correlated with esophageal pressures [56]. Similarly, others have used a combination of sniff maneuvers and ultrasonography [79] to assess diaphragm fatigue.…”