Inspiratory muscle performance in endurance-trained elderly males during incremental exercise

• Progressive decline in lung function with aging specifically decrease respiratory muscle strength, increased in the work of breathing and oxygen cost of breathing (VO2resp) and expiratory flow limitation even during mild-to-moderate exercise.
• Alterations in the inspiratory neural drive in elderly subjects were characterized by a higher mouth occlusion pressure (P0.1) at submaximal exercise levels, compared to control subjects and reduced ventilatory responses to both hypercapnia and hypoxia.
• Reduced energy demand (P0.1/PImax) after endurance training is a consequence of exercise training (i.e., lower central respiratory drive and/or higher global inspiratory muscle strength) indicates improved respiratory capacity. The lower inspiratory demand (in relation to the inspiratory reserve) explains the lower TT0.1 in trained groups.
• Increase in the inspiratory muscle’s efficiency (decreased TT0.1) may lead to lower energy demand to the same VCO2, and thus to a lower risk of inspiratory muscle weakness, and to improved exercise performance in a trained group.

The aim of this study was to compare the inspiratory muscle performance during an incremental exercise of twelve fit old endurance-trained athletes (OT) with that of fit young athletes (YT) and healthy age-matched controls (OC). The tension-time index (TT0.1) was determined according to the equation TT0.1 = P0.1/PImax × ti/ttot, where P0.1 is the mouth occlusion pressure, PImax the maximal inspiratory pressure and ti/ttot the duty cycle. For a given VCO2, OT group displayed P0.1, P0.1/PImax ratio, TT0.1 and effective impedance of the respiratory muscle values which were lower than OC group and higher than YT group. At maximal exercise, P0.1/PImax ratio and TT0.1 was still lower in the OT group than OC group and higher than YT group. This study showed lower inspiratory muscle performance attested by a higher (TT0.1) during exercise in the OT group than YT group, but appeared to be less marked in elderly men having performed lifelong endurance training compared with sedentary elderly subjects.