Three weeks of respiratory muscle endurance training improve the O2 cost of walking and exercise tolerance in obese adolescents.

Hailu K Alemayehu,Desy Salvadego,Bruno Grassi,Miriam Isola,Mara Caccavale,Roberta De Micheli,Gabriella Tringali,Alessandro Sartorio

doi:10.14814/phy2.13888

Hailu K Alemayehu, Desy Salvadego + Show 6 more

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https://doi.org/10.14814/phy2.13888

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Abstract

Obese adolescents (OB) have an increased O2 cost of exercise, attributable in part to an increased O2 cost of breathing. In a previous work a short (3‐week) program of respiratory muscle endurance training (RMET) slightly reduced in OB the O2 cost of high‐intensity cycling and improved exercise tolerance. We hypothesized that during treadmill walking the effects of RMET would be more pronounced than those observed during cycling. Sixteen OB (age 16.0 ± 0.8 years; body mass [BM] 127.7 ± 14.2 kg; body mass index 40.7 ± 4.0 kg/m2) underwent to 3‐week RMET (n = 8) superimposed to a multidisciplinary BM reduction program, or (CTRL, n = 8) only to the latter. Heart rate (HR) and pulmonary O2 uptake (V˙O2) were measured during incremental exercise and 12‐min constant work rate (CWR) walking at 60% (moderate‐intensity, MOD) and 120% (heavy‐intensity, HEAVY) of the gas exchange threshold (GET). The O2 cost of walking (aerobic energy expenditure per unit of covered distance) was calculated as V˙O2/velocity. BM decreased (~4–5 kg) both in CTRL and in RMET. V˙O2peak and GET were not affected by both interventions; the time to exhaustion increased following RMET. During MOD and HEAVY RMET decreased V˙O2, the O2 cost of walking (MOD: 0.130 ± 0.033 mL/kg/m [before] vs. 0.109 ± 0.027 [after], P = 0.03; HEAVY: 0.196 ± 0.031 [before] vs. 0.180 ± 0.025 [after], P = 0.02), HR and rates of perceived exertion; no significant changes were observed in CTRL. In OB a short RMET program lowered the O2 cost of MOD and HEAVY walking and improved exercise tolerance. RMET could represent a useful adjunct in the control of obesity.

Highlights

The results suggest that during weight bearing activities like walking or running, in which larger muscle masses are involved compared to cycling, and the patient undergoes cyclical elevations and accelerations of the body’s center of mass at every step, obese adolescents are penalized, from the O2 cost of exercise point of view, during moderate-intensity exercise
As well as in our previous one (Salvadego et al 2017) carried out in obese adolescents, we provide objective evidence of efficacy, in terms of a reduced inefficiency of oxidative metabolism, which was associated with objective evidence of enhanced exercise tolerance
The present study, carried out on obese adolescents walking on a treadmill, extends the positive effects of a short (3week) respiratory muscle endurance training (RMET) program on the O2 cost of exercise and on exercise tolerance, previously described by our group in obese adolescents only during heavy-intensity cycling exercise (Salvadego et al 2017), during moderate-intensity exercise

Summary

Introduction

Obese patients have a higher O2 cost of exercise (Wasserman and Whipp 1975; Lafortuna et al 2008; Salvadego et al 2010), which negatively affects exercise tolerance (Grassi et al 2015) and is at least in part attributable to a higher O2 cost of breathing (Kress et al 1999; Salvadego et al 2015, 2017). In association with respiratory muscle inefficiency, the increased work of breathing determines a substantially higher O2 cost of breathing (Koenig 2001), contributing to the higher O2 cost of exercise (Wasserman and Whipp 1975; Salvadego D et al 2010; Salvadego et al 2015, 2017) This is exacerbated by the higher pulmonary ventilation at the same work rate observed in obese patients versus normal weight controls (Cherniack 1959; Kress et al 1999), possibly leading to exertional dyspnea (Scano et al 2009)

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