Effect of Inspiratory Muscle Training Intensities on Pulmonary Function and Work Capacity in People Who Are Healthy: A Randomized Controlled Trial

Wales College of Medicine, Biology, Life and Health Sciences, Cardiff University, Heath Park, Cardiff, United Kingdom.
Physical Therapy (Impact Factor: 2.53). 06/2011; 91(6):894-905. DOI: 10.2522/ptj.20090413
Source: PubMed


Inspiratory muscle training (IMT) has been shown to improve inspiratory muscle function, lung volumes (vital capacity [VC] and total lung capacity [TLC]), work capacity, and power output in people who are healthy; however, no data exist that demonstrate the effect of varying intensities of IMT to produce these outcomes.
The purpose of this study was to evaluate the impact of IMT at varying intensities on inspiratory muscle function, VC, TLC, work capacity, and power output in people who are healthy.
This was a randomized controlled trial.
The study was conducted in a clinical laboratory.
Forty people who were healthy (mean age=21.7 years) were randomly assigned to 4 groups of 10 individuals.
Three of the groups completed an 8-week program of IMT set at 80%, 60%, and 40% of sustained maximum inspiratory effort. Training was performed 3 days per week, with 24 hours separating training sessions. A control group did not participate in any form of training.
Baseline and posttraining measurements of body composition, VC, TLC, inspiratory muscle function (including maximum inspiratory pressure [MIP] and sustained maximum inspiratory pressure [SMIP]), work capacity (minutes of exercise), and power output were obtained.
The participants in the 80%, 60%, and 40% training groups demonstrated significant increases in MIP and SMIP, whereas those in the 80% and 60% training groups had increased work capacity and power output. Only the 80% group improved their VC and TLC. The control group demonstrated no change in any outcome measures.
This study may have been underpowered to demonstrate improved work capacity and power output in individuals who trained at 40% of sustained maximum inspiratory effort.
High-intensity IMT set at 80% of maximal effort resulted in increased MIP and SMIP, lung volumes, work capacity, and power output in individuals who were healthy, whereas IMT at 60% of maximal effort increased work capacity and power output only. Inspiratory muscle training intensities lower than 40% of maximal effort do not translate into quantitative functional outcomes.

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Available from: Viswanath Unnithan, Jan 05, 2016
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    • "The PREPARE study is the first to use a high intensity training protocol in the preoperative phase. Based on promising results in healthy adults [34] and patients with COPD [14] the PREPARE team chose to use a high intensity training program proposed by Bailey et al. [18]. The protocol of 30 breaths twice daily is easy to perform unsupervised and will take only a few minutes per training session, possibly resulting in higher compliance to this specific training. "
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    ABSTRACT: Esophageal resection is associated with a high incidence of postoperative pneumonia. Respiratory complications account for almost half of the readmissions to the critical care unit. Postoperative complications can result in prolonged hospital stay and consequently increase healthcare costs. In cardiac surgery a preoperative inspiratory muscle training program has shown to prevent postoperative pneumonia and reduce length of hospital stay. While in some surgical centers inspiratory muscle training is already used in the preoperative phase in patients undergoing esophageal resection, the added value of this intervention on the reduction of pulmonary complications has not yet been investigated in large surgical populations other than cardiac surgery in a randomized and controlled study design.Methods/design: The effect of a preoperative inspiratory muscle training program on the incidence of postoperative pneumonia in patients undergoing esophageal resection will be studied in a single blind multicenter randomized controlled trial (the PREPARE study). In total 248 patients (age >18 years) undergoing esophageal resection for esophageal cancer will be included in this study. They are randomized to either usual care or usual care with an additional inspiratory muscle training intervention according to a high-intensity protocol which is performed with a tapered flow resistive inspiratory loading device. Patients have to complete 30 dynamic inspiratory efforts twice daily for 7 days a week until surgery with a minimum of 2 weeks. The starting training load will be aimed to be 60% of maximal inspiratory pressure and will be increased based on the rate of perceived exertion.The main study endpoint is the incidence of postoperative pneumonia. Secondary objectives are to evaluate the effect of preoperative inspiratory muscle training on length of hospital stay, duration of mechanical ventilation, incidence of other postoperative (pulmonary) complications, quality of life, and on postoperative respiratory muscle function and lung function. The PREPARE study is the first multicenter randomized controlled trial to evaluate the hypothesis that preoperative inspiratory muscle training leads to decreased pulmonary complications in patients undergoing esophageal resection.Trial registration: NCT01893008.
    Full-text · Article · Apr 2014 · Trials
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    • "Endurance capacity depends on respiratory function in addition to circulatory and muscular function, and for this reason, there has recently been considerable interest in the relationship between respiratory muscle training, which aims to improve respiratory muscle function, and cardiorespiratory endurance. Some studies have reported that inspiratory muscle training during rest improves the cardiorespiratory endurance of patients with weakened respiratory muscles and that of healthy adults7,8,9,10,11), whereas other studies have reported no effect12,13,14,15). Thus, there is no consensus of opinion. "
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    ABSTRACT: [Purpose] In this study, combined training with breathing resistance and sustained physical exertion was carried out to evaluate its physiological effects and its effect on improve endurance capacity. [Subjects and Methods] The subjects were nine healthy adults (mean age 20.4, SD ± 1.7 years). The combined training group (n = 5) carried out 6 weeks of combined training using a cycle ergometer, with exercise load tests and respiratory function tests performed before and after the training. The results of the training were compared to a control group (n = 4) that only performed the cycling exercise without the combined training with breathing resistance. [Results] In the combined training group, ventilatory threshold, maximal load of the cycle ergometer in exercise load tests, and maximal voluntary ventilation increased after training. These increases after training were all significant, but none of these variables changed significantly in the control group. [Conclusion] The results imply that in comparison to conventional training methods, combined training with breathing resistance and sustained physical exertion is beneficial for increasing endurance capacity and respiratory muscle function. This result provides important information regarding the effects of the new training method for improving endurance capacity.
    Full-text · Article · May 2013 · Journal of Physical Therapy Science
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    • "Enright and Unnithan. (2011) found an increase in VC after 8-week IMT program (80% of sustained maximum inspiratory effort, 3times/week inconsecutively) (22). Shaw, , and Brown. "
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    ABSTRACT: Objective(s): As not only few evidences but also contradictory results exist with regard to the effects of resistance training (RT) and resistance plus endurance training (ERT) on respiratory system, so the purpose of this research was therefore to study single and concurrent effects of endurance and resistance training on pulmonary function. Materials and Methods: Thirty seven volunteer healthy inactive women were randomly divided into 4 groups: without training as control (C), Endurance Training (ET), RT, and ERT. A spirometry test was taken 24 hrs before and after the training course. The training period (8 weeks, 3 sessions/week) for ET was 20-26 min/session running with 60-80% maximum heart rate (HR max); for RT two circuits/session, 40-60s for each exercise with 60-80% one repetition maximum (1RM), and 1 and 3 minutes active rest between exercises and circuits respectively; and for ERT was in agreement with either ET or RT protocols, but the times of running and circuits were half of ET and RT. Results: ANCOVA showed that ET and ERT increased significantly (P< 0.05) vital capacity (VC), forced vital capacity (FVC), and forced expiratory flows to 25%-75%; ET, RT and ERT increased significantly (P< 0.05) maximum voluntary ventilation (MVV); and only ET increased significantly (P<0.05) peak expiratory flows (PEF); but ET, RT and ERT had no significant effect (P>0.05) on forced expiratory volume in one second (FEV1) and FEV1/FVC ratio. Conclusion: In conclusion, ET combined with RT (ERT) has greater effect on VC, FVC, FEF rating at25%-75%, and also on PEF except MVV, rather than RT, and just ET has greater effect rather than ERT.
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