Keens TG, Krastins IR, Wannamaker EM, Levison H, Crozier DN and Bryan AC.
Ventilatory muscles can become fatigued, and this can contribute to respiratory failure. Patients with chronic obstructive lung disease may benefit from improving their ventilatory muscle endurance to improve resistance to fatigue. Ventilatory muscle endurance was measured in 30 normal subjects and 55 patients with cystic fibrosis by finding the highest level of normocapnic hyperpnea that could be sustained for 15 min. Subjects with cystic fibrosis had 36 per cent higher ventilatory muscle endurance than normal subjects, reflecting the chronic training stress of breathing against increased respiratory loads. Four normal subjects and 4 subjects with cystic fibrosis participated in a specific ventilatory muscle endurance training program consisting of 25 min per day of maximal normocapnic hyperpnea 5 days per week for 4 weeks. The cystic fibrosis patients who trained improved their ventilatory muscle endurance by 51.6 per cent, whereas the normal subjects who trained showed a 22.1 per cent increase in ventilatory muscle endurance. Seven subjects with cystic fibrosis participated in a 4-week physical activity training program consisting of at least 1.5 hours per day of intensive swimming and canoeing at summer camp. They increased their ventilatory muscle endurance by 56.7 per cent. There were no other pulmonary function changes. Ventilatory muscle endurance can be readily improved in cystic fibrosis equally well by specific ventilatory muscle endurance exercise.
PMID: 921061 DOI: 10.1164/arrd.19126.96.36.1993
McConnell AK, Romer LM.
Specific respiratory muscle training offers the promise of improved exercise tolerance and athletic performance for a wide range of users. However, the literature addressing respiratory muscle training in healthy people remains controversial. Studies into the effect of respiratory muscle training upon whole body exercise performance have used at least one of the following modes of training: voluntary isocapnic hyperpnea, flow resistive loading, and pressure threshold loading. Each of these training modes has the potential to improve specific aspects of respiratory muscle function. Some studies have demonstrated significant improvements in either time to exhaustion or time trial performance, whilst others have demonstrated no effect. We present an overview of the literature that rationalizes its contradictory findings. Retrospective analysis of the literature suggests that methodological factors have played a crucial role in the outcome of respiratory muscle training studies. We conclude that in most well controlled and rigorously designed studies, utilizing appropriate outcome measures, respiratory muscle training has a positive influence upon exercise performance. The mechanisms by which respiratory muscle training improves exercise performance are unclear. Putative mechanisms include a delay of respiratory muscle fatigue, a redistribution of blood flow from respiratory to locomotor muscles, and a decrease in the perceptions of respiratory and limb discomfort.
PMID: 15162248 DOI: 10.1055/s-2004-815827
Edwards AM, Graham D, Bloxham S and Maguire GP
To examine the efficacy of inspiratory muscle training (IMT) as a non-intrusive and practical intervention to stimulate improved functional fitness in adults with obesity. As excess adiposity of the chest impedes the mechanics of breathing, targeted re-training of the inspiratory muscles may ameliorate sensations of breathlessness, improve physical performance and lead to greater engagement in physical activity.
Sixty seven adults (BMI=36±6.5) were randomized into either an experimental (EXP: n=35) or placebo (PLA: n=32) group with both groups undertaking a 4-week IMT intervention, comprising daily use of a inspiratory resistance device set to 55% (EXP), or 10% (PLA) of maximum inspiratory effort.
Inspiratory muscle strength was significantly improved in EXP (19.1 cmH20 gain; P<0.01) but did not change in PLA. Additionally, the post training walking distance covered was significantly extended for EXP (P<0.01), but not for PLA. Bivariate analysis demonstrated a positive association between the change (%) of performance in the walking test and BMI (r=0.78; P<0.01) for EXP.
The findings from this study suggest IMT provides a practical, self-administered intervention for use in a home setting. This could be a useful strategy to improve the functional fitness of obese adults and perhaps lead to better preparedness for engagement in physical activity initiatives.
Copyright © 2016. Published by Elsevier B.V.
Chronic disease; Obesity; Physical activity; Respiratory disorders
PMID: 27638058 DOI: 10.1016/j.resp.2016.09.007
West CR, Taylor BJ, Campbell IG and Romer LM.
We asked whether specific inspiratory muscle training (IMT) improves respiratory structure and function and peak exercise responses in highly trained athletes with cervical spinal cord injury (SCI). Ten Paralympic wheelchair rugby players with motor-complete SCI (C5-C7) were paired by functional classification then randomly assigned to an IMT or placebo group. Diaphragm thickness (B-mode ultrasonography), respiratory function [spirometry and maximum static inspiratory (PI ,max ) and expiratory (PE ,max ) pressures], chronic activity-related dyspnea (Baseline and Transition Dyspnea Indices), and physiological responses to incremental arm-crank exercise were assessed before and after 6 weeks of pressure threshold IMT or sham bronchodilator treatment. Compared to placebo, the IMT group showed significant increases in diaphragm thickness (P = 0.001) and PI ,max (P = 0.016). There was a significant increase in tidal volume at peak exercise in IMT vs placebo (P = 0.048) and a strong trend toward an increase in peak work rate (P = 0.081, partial eta-squared = 0.33) and peak oxygen uptake (P = 0.077, partial eta-squared = 0.34). No other indices changed post-intervention. In conclusion, IMT resulted in significant diaphragmatic hypertrophy and increased inspiratory muscle strength in highly trained athletes with cervical SCI. The strong trend, with large observed effect, toward an increase in peak aerobic performance suggests IMT may provide a useful adjunct to training in this population.
diaphragm; respiratory; tetraplegia; upper-body exercise; wheelchair sport
PMID: 23530708 DOI: 10.1111/sms.12070
Yamada S, Hashizume A, Hijikata Y, Inagaki T, Suzuki K Kondo N, Kawai K, Noda S, Nakanishi H, Banno H, Hirakawa A, Koike H, Halievski K, Jordan CL, Katsuno M and Sobue G.
The aim of this study was to characterize the respiratory function profile of subjects with spinal and bulbar muscular atrophy (SBMA), and to explore the underlying pathological mechanism by comparing the clinical and biochemical indices of this disease with those of amyotrophic lateral sclerosis (ALS). We enrolled male subjects with SBMA (n = 40) and ALS (n = 25) along with 15 healthy control subjects, and assessed their respiratory function, motor function, and muscle strength. Predicted values of peak expiratory flow (%PEF) and forced vital capacity were decreased in subjects with SBMA compared with controls. In SBMA, both values were strongly correlated with the trunk subscores of the motor function tests and showed deterioration relative to disease duration. Compared with activities of daily living (ADL)-matched ALS subjects, %PEF, tongue pressure, and grip power were substantially decreased in subjects with SBMA. Both immunofluorescence and RT-PCR demonstrated a selective decrease in the expression levels of the genes encoding the myosin heavy chains specific to fast-twitch fibers in SBMA subjects. The mRNA levels of peroxisome proliferator-activated receptor gamma coactivator 1-alpha and peroxisome proliferator-activated receptor delta were up-regulated in SBMA compared with ALS and controls. In conclusion, %PEF is a disease-specific respiratory marker for the severity and progression of SBMA. Explosive muscle strength, including %PEF, was selectively affected in subjects with SBMA and was associated with activation of the mitochondrial biogenesis-related molecular pathway in skeletal muscles.
PMID: 28005993 PMCID: PMC5179045 DOI: 10.1371/journal.pone.0168846