Effects of inspiratory muscle training versus high intensity interval training on the recovery capacity after a maximal dynamic apnoea in breath-hold divers. A randomised crossover trial

Abstract

(de Asís-Fernández F, del Corral T, López-de-Uralde-Villanueva I. Effects of inspiratory muscle training versus high intensity interval training on the recovery capacity after a maximal dynamic apnoea in breath-hold divers. A randomised crossover trial. Diving and Hyperbaric Medicine. 2020 December 20;50(4):318–324. doi: 10.28920/dhm50.4.318-324. PMID: 33325010.) Introduction: After a maximal apnoea, breath-hold divers must restore O2 levels and clear CO2 and lactic acid produced. High intensity interval training (HIIT) and inspiratory muscle training (IMT) could be employed with the aim of increasing recovery capacity. This study aimed to evaluate the relative effects of IMT versus HIIT on recovery of peripheral oxygen saturation (SpO2), and also on pulmonary function, inspiratory muscle strength, lactate and heart rate recovery after a maximal dynamic apnoea in breath-hold divers. Methods: Fifteen breath-hold divers performed two training interventions (IMT and HIIT) for 20 min, three days per week over four weeks in randomised order with a two week washout period. Results: IMT produced a > 3 s reduction in SpO2 recovery time compared to HIIT. The forced expiratory volume in the first second (FEV1) and maximum inspiratory pressure (MIP) were significantly increased in the IMT group compared to HIIT. The magnitude of these differences in favour of IMT was large in both cases. Neither training intervention was superior to the other for heart rate recovery time, nor in peak- and recovery- lactate. Conclusions: IMT produced a reduction in SpO2 recovery time compared to HIIT after maximal dynamic apnoea. Even a 3 s improvement in recovery could be important in scenarios like underwater hockey where repetitive apnoeas during high levels of exercise are separated by only seconds. IMT also improved FEV1 and MIP, but no differences in lactate and heart rate recovery were found post-apnoea between HIIT and IMT.