PURPOSE: Patients with type 2 diabetes mellitus may present weakness of the inspiratory muscles. We tested the hypothesis that inspiratory muscle training (IMT) could improve inspiratory muscle strength, pulmonary function, functional capacity, and autonomic modulation in patients with type 2 diabetes and weakness of the inspiratory muscles.
METHODS: Maximal inspiratory muscle pressure (PImax) was evaluated in a sample of 148 patients with type 2 diabetes. Of these, 25 patients with PImax<70% of predicted were randomized to an 8-wk program of IMT (n=12) or placebo-IMT (n=13). PImax, inspiratory muscle endurance time, pulmonary function, peak oxygen uptake, and HR variability were evaluated before and after intervention.
RESULTS: The prevalence of inspiratory muscle weakness was 29%. IMT significantly increased the PImax (118%) and the inspiratory muscle endurance time (495%), with no changes in pulmonary function, functional capacity, or autonomic modulation. There were no significant changes with placebo-IMT.
CONCLUSIONS: Patients with type 2 diabetes may frequently present inspiratory muscle weakness. In these patients, IMT improves inspiratory muscle function with no consequences in functional capacity or autonomic modulation.
PMID: 21200342 DOI: 10.1249/MSS.0b013e31820a7c12

Obstructive sleep apnea (OSA) is a disease defined by airflow limitations (hypopneas) and/or complete obstructions (apneas) throughout the night, and severity is indicated by the number of events per hour of sleep or apnea hypopnea index (AHI). OSA patients experience disrupted sleep and are at greater risk for hypertension, cardiovascular disease, and stroke. Unfortunately, the gold-standard of treatment for OSA, continuous positive airway pressure (CPAP), has discouraging compliance rates. Here, we report on inspiratory muscle strength training (IMST) as a potential new treatment for OSA. Mild-moderate sleep apnea patients underwent six-weeks of IMST. Training consisted of 30 breaths daily, for 6 weeks, using a take-home inspiratory resistance device (POWERbreathe® K3 series). Subjects were randomly assigned to a treatment group: training (75% of maximal inspiratory pressure (PI)) or placebo (15% of PI). max max Pre-and post-assessment measures included: overnight polysomnography (PSG), Pittsburgh sleep quality index (PSQI), spirometry, blood pressure, and PI. We find individuals in the max training group exhibit reductions in PSQI scores (11.0±0.9 vs. 6.0±1.4, pre-post) relative to placebo (10.0±1.1 vs. 9.9±0.7, pre-post). Additionally, individuals in the training group exhibit pre-post reductions in systolic and diastolic blood pressures (131.5±3.1/83.5±2.7 vs. 121.6±2.5/77.4±1.3) relative to placebo (129.8±4.8/80.6±3.1 vs. 131.9±5.0/84.6±2.7). We saw no change in AHI, however PSG results show reductions in periodic limb movement indices in training subjects (32.4 vs. 15.6, pre-post) relative to placebo (11.7 vs. 13.8, pre-post). Individuals in the training group also show improvements in the proportion of time spent in non-REM sleep (70.7% vs. 77.2%, pre-post) relative to placebo (72.0% vs. 74.6%, pre-post). In summary, individuals undertaking 6 weeks of IMST show improvements in: perceived sleep quality, proportion of consolidated sleep time, periodic limb movements, and systolic and diastolic blood pressures when compared to individuals in a placebo group. These results support IMST as a treatment that can improve the cardiovascular and sleep quality parameters in individuals with mild-moderate OSA.

BACKGROUND: The cardiovascular system is noticeably affected by respiration. However, whether different inspiratory resistive loading intensities can influence autonomic heart rate (HR) modulation remains unclear.
OBJECTIVE: The objective was to investigate HR modulation at three different inspiratory resistive loading intensities in healthy elderly men.
METHOD: This was a prospective, randomized, double-blind study that evaluated 25 healthy elderly men. Cardiac autonomic modulation was assessed using heart rate variability (HRV) indices. All of the volunteers underwent maximal inspiratory pressure (MIP) measurements according to standardized pulmonary function measurements. Three randomly-applied inspiratory resistive loading (30, 60 and 80% of MIP) intensities were then applied using an inspiratory resistance device (POWERbreathe, Southam, UK), during which the volunteers were asked to inhale for 2 seconds and exhale for 3 seconds and complete 12 breaths per minute. Each effort level was performed for 4 minutes, and HR and the distance between 2 subsequent R waves of electrocardiogram (R-R intervals) were collected at rest and at each intensity for further HRV analysis.
RESULTS: The parasympathetic HRV (rMSSD, SD1 and HF) indices demonstrated lower values at 80% (rMSSD: 19±2 ms, SD1: 13±2 ms and HF: 228±61 ms2) than at 30% MIP (rMSSD: 25±3 ms, SD1: 18±2 ms and HF: 447±95 ms2; p<0.05).
CONCLUSIONS: Lower inspiratory resistive loading intensities promoted a marked and positive improvement of parasympathetic sinus node modulation.
PMID: 23970114 DOI: 10.1590/S1413-35552012005000100

The purpose of this study is to evaluate the effects of postoperative inspiratory muscle training on the recovery of respiratory muscle strength in high risk patients referred for lung cancer surgery. Furthermore, to assess longitudinal changes in respiratory muscle strength, physical capacity and health-related quality of life after lung cancer surgery

PURPOSE: We have shown that individuals with recurrent nonspecific low back pain (LBP) and healthy individuals breathing against an inspiratory load decrease their reliance on back proprioceptive signals in upright standing. Because individuals with LBP show greater susceptibility to diaphragm fatigue, it is reasonable to hypothesize that LBP, diaphragm dysfunction, and proprioceptive use may be interrelated. The purpose of this study was to investigate whether inspiratory muscle training (IMT) affects proprioceptive use during postural control in individuals with LBP.
METHODS: Twenty-eight individuals with LBP were assigned randomly into a high-intensity IMT group (high IMT) and low-intensity IMT group (low IMT). The use of proprioception in upright standing was evaluated by measuring center of pressure displacement during local muscle vibration (ankle, back, and ankle-back). Secondary outcomes were inspiratory muscle strength, severity of LBP, and disability.
RESULTS: After high IMT, individuals showed smaller responses to ankle muscle vibration, larger responses to back muscle vibration, higher inspiratory muscle strength, and reduced LBP severity (P < 0.05). These changes were not seen after low IMT (P > 0.05). No changes in disability were observed in either group (P > 0.05).
CONCLUSIONS: After 8 wk of high IMT, individuals with LBP showed an increased reliance on back proprioceptive signals during postural control and improved inspiratory muscle strength and severity of LBP, not seen after low IMT. Hence, IMT may facilitate the proprioceptive involvement of the trunk in postural control in individuals with LBP and thus might be a useful rehabilitation tool for these patients.
PMID: 24870567 DOI: 10.1249/MSS.0000000000000385