Respiratory muscle function and ventilatory patterns in adolescent males

Respiratory muscle function has become prevalent within the literature recently, with specific reference to both disease and athletic populations however, there is limited data pertaining to the healthy and recreationally active adolescent population. PURPOSE: The aim of this study was to investigate the relationship between Inspiratory and Expiratory Muscle strength and pulmonary function at rest and during peak exercise, in an adolescent population. METHODS: Fourteen healthy recreationally active males (age 17 +/- 0.9 yrs; stature 1.81 +/-0.76m; body mass 72.0+/-8.8kg) provided informed written parental permission and subjects' assent. The study was approved by institutional research ethics committee. In an initial lab visit each subject underwent full familiarisation with all testing protocols. In a second lab visit subjects completed resting pulmonary function (FVC FEV1.0)[Micro-Loop, micro medical UK] and respiratory muscle function (Maximal Inspiratory Pressure: MIP; Maximal Expiratory Pressure: MEP)[Micro-RPM, micro medical UK]. Subjects then pedalled in the upright position at a cadence of 60 rpm on an electronically braked cycle ergometer (Excalibur Sport 925900; Lode, Groningen, Netherlands). Initial and incremental loads of 40 Watts were applied at 4-min intervals for two stages then reduced to 3-min stages of 40 Watt increments to the point of exhaustion (the point when pedal cadence could no longer be maintained). Gas exchange values were obtained using standard open-circuit techniques (Zan 600; nSpire Health Oberthulba, Germany) while minute ventilation was assessed via pneumotachometer. RESULTS: Resting values were considered normal, FVC (5.72 +/-0.85L) FEV1.0(4.79 +/- 0.94L) MIP (114 +/- 25cmH20) MEP 112 +/-31cmH20) VE (9.96 +/-1.89L) Bf (16+/- 3) TV (0.72 +/-0.22L). Peak Exercise values were also regarded as normal VE peak (124.25 +/-25.14L) Bfpeak (46+/- 10 breaths) TVpeak (2.76+/-0.42L) VO2peak (44.8 +/- 4.6ml/kg/min). The only significant correlation that occurred was between MIP and VE peak (r = 0.60; p<0.05). CONCLUSIONS: Respiratory muscle strength, in the form of MIP is positively correlated with VEpeak in recreationally active adolescent subjects. However there does not appear to be any further relationship between MIP, MEP and ventilation at rest or peak exercise.