Repeated abdominal exercise induces respiratory muscle fatigue

Prolonged bouts of hyperpnea or resisted breathing are known toresult in respiratory muscle fatigue, as are primarily non respiratoryexercises such as maximal running and cycling. theseexercises have a large ventilatory component, though, and canstill be argued to be respiratory activities. sit-up training hasbeen used to increase respiratory muscle strength, but no studieshave been done to determine whether this type of nonrespiratoryactivity can lead to respiratory fatigue. the purposeof the study was to test the effect of sit-ups on various respiratorymuscle strength and endurance parameters. eight subjectsperformed pulmonary function, maximum inspiratory pressure(mip) and maximum expiratory pressure (mep) measurements,and an incremental breathing test before and after completing aone-time fatiguing exercise bout of sit-ups. each subject actedas their own control performing the same measurements 3-5days following the exercise bout, substituting rest for exercise.following sit-up induced fatigue, significant decreases weremeasured in mip [121.6 ± 26 to 113.8 ± 23 cmh2o (p <0.025)],and incremental breathing test duration [9.6 ± 1.5 to 8.5 ± 0.7minutes (p <0.05)]. no significant decreases were observedfrom control pre-test to control post-test measurements. weconclude that after a one-time fatiguing sit-up exercise boutthere is a reduction in respiratory muscle strength (mip, mep)and endurance (incremental breathing test duration) but notspirometric pulmonary function.