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.

Despite different work history, RMSIT appears to place a metabolic load on respiratory muscles similarly to RMET and could therefore be considered a time-saving and safe training alternative.

No abstract