Andrew D. Ray

A Combined Inspiratory and Expiratory Muscle Training Program Improves Respiratory Muscle Strength and Fatigue in Multiple Sclerosis

OBJECTIVE To determine the effects of a short-duration, combined (inspiratory and expiratory), progressive resistance respiratory muscle training (RMT) protocol on respiratory muscle strength, fatigue, health-related quality of life, and functional performance in individuals with mild-to-moderate multiple sclerosis (MS). DESIGN Quasi-experimental before-after trial. SETTING University rehabilitation research laboratory. PARTICIPANTS Volunteers with MS (N=21) were divided into 2 groups: RMT (n=11; 9 women, 2 men; mean age ± SD, 50.9 ± 5.7y, mean Expanded Disability Status Scale score ± SD, 3.2 ± 1.9) and a control group that did not train (n=10; 7 women, 3 men; mean age ± SD, 56.2 ± 8.8y, mean Expanded Disability Status Scale score ± SD, 4.4 ± 2.1). Expanded Disability Status Scale scores ranged from 1 to ≤6.5. No patients withdrew from the study. INTERVENTION Training was a 5-week combined progressive resistance RMT program, 3d/wk, 30 minutes per session. MAIN OUTCOME MEASURES The primary outcome measures were maximal inspiratory pressure and expiratory pressure and the Modified Fatigue Impact Scale. All subjects completed secondary measures of pulmonary function, the six-minute walk test, the timed stair climb, the Multiple Sclerosis Self-Efficacy Scale, the Medical Outcomes Study 36-Item Short-Form Health Survey, and the Physical Activity Disability Scale. RESULTS Maximal inspiratory pressure and expiratory pressure (mean ± SD) increased 35% ± 22% (P<.001) and 26% ± 17% (P<.001), respectively, whereas no changes were noted in the control group (12% ± 23% and -4% ± 17%, respectively). RMT improved fatigue (Modified Fatigue Impact Scale, P<.029), with no change or worsening in the control group. No changes were noted in the six-minute walk test, stair climb, Multiple Sclerosis Self-Efficacy Scale, or Physical Activity Disability Scale in the RMT group. The control group had decreases in emotional well-being and general health (Medical Outcomes Study 36-Item Short-Form Health Survey). CONCLUSIONS A short-duration, combined RMT program improved inspiratory and expiratory muscle strength and reduced fatigue in patients with mild to moderate MS.

Aging increases upper airway collapsibility in Fischer 344 rats

The upper airway muscles play an important role in maintaining upper airway collapsibility, and the incidence of sleep-disordered breathing increases with age. We hypothesize that the increase in airway collapsibility with increasing age can be linked to changes in upper airway muscle mechanics and structure. Eight young (Y: 6 mo) and eight old (O: 30 mo) Fischer 344 rats were anesthetized and mechanically ventilated, and the pharyngeal pressure associated with flow limitation (Pcrit) was measured 1) with the hypoglossal (cnXII) nerve intact, 2) following bilateral cnXII denervation, and 3) during cnXII stimulation. With the cnXII intact, the upper airways of older rats were more collapsible compared with their younger counterparts [Pcrit = -7.1 +/- 0.6 (SE) vs. -9.5 +/- 0.7 cmH2O, respectively; P = 0.033]. CnXII denervation resulted in an increase in Pcrit such that Pcrit became similar in both groups (O: -4.2 +/- 0.5 cmH2O; Y: -5.4 +/- 0.5 cmH2O). In all rats, cnXII stimulation decreased Pcrit (less collapsible) in both groups (O: -11.3 +/- 1.0 cmH2O; Y: -10.2 +/- 1.0 cmH2O). The myosin heavy chain composition of the genioglossus muscle demonstrated a decrease in the percentage of the IIb isoform (38.3 +/- 2.5 vs. 21.7 +/- 1.7%; P < 0.001); in contrast, the sternohyoid muscle demonstrated an increase in the percentage of the IIb isoform (72.2 +/- 2.5 vs. 58.4 +/- 2.3%; P = 0.001) with age. We conclude that the upper airway becomes more collapsible with age and that the increase in upper airway collapsibility with age is likely related to altered neural control rather than to primary alterations in upper airway muscle structure and function.

Exercise capacity in hamsters with elastase-induced emphysema compared to normal controls.

The purpose of this study was to determine whether hamsters with elastase-induced emphysema (EMP) would demonstrate a reduction in exercise capacity compared to control (CON) hamsters and whether changes in activity levels, muscle function and structure could explain any changes in exercise capacity. Peak oxygen consumption and daily activity levels were measured on two occasions. Inspiratory capacity under deep anesthesia, in vitro measurements of muscle force and fatigability for the diaphragm (DIA) and extensor digitorum longus (EDL) and fiber proportions, muscle cross-sectional area and fiber specific SDH activity from the DIA, EDL and vastus lateralis (VLA) were obtained. Inspiratory capacity was 60% higher in the EMP compared to CON hamsters (p=0.0004). Activity levels and exercise capacity were not significantly different between EMP and CON hamsters. Muscle strength and fatigability, fiber proportions, muscle cross-sectional area and fiber specific SDH activity were similar between EMP and CON hamsters. In conclusion, in hamsters, elastase-induced emphysema did not reduce maximal exercise capacity.

Measures of respiratory function correlate with fatigue in ambulatory persons with multiple sclerosis

Abstract Purpose: This article examines the association between measures of respiratory muscle function and fatigue in individuals with mild-to-moderate disability multiple sclerosis (MS). Methods: This was a cross-sectional study of 37 ambulatory volunteers with MS (28 F/9 M, 52.7 ± 10.2 years, Expanded Disability Status Scale [EDSS] = 3.5 ± 1.9). No patients withdrew from the study. Primary outcome variables included measures of respiratory function: maximal inspiratory (MIP) and expiratory pressures (MEP), forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), maximal voluntary ventilation (MVV12); and a self-reported measure of fatigue: the Modified Fatigue Impact Scale (MFIS). Secondary measures included 6-min walking test (6MWT), a timed stair climb, the Short Form (SF)-36, the Epworth Sleepiness Scale and the Physical Activity and Disability Scale (PADS). Results: Significant correlations were shown between expiratory muscle strength (MEP) and the MFIS total (p < 0.03, r = –0.362) and between MEP and physical fatigue scores (p < 0.03, r = –0.360), as well as between MVV12 percent predicted (respiratory muscle endurance) and both the 6MWT (p = 0.045, r = 0.346) and the Epworth Sleepiness Scale (p = 0.006, r = 0.447). Conclusions: Respiratory muscle performance is correlated with perceived fatigue (MFIS), whereas respiratory endurance correlated to reductions in physical function and sleep quality among individuals with mild-to-moderate severity MS. Implications for Rehabilitation Multiple sclerosis (MS) results in peripheral and respiratory muscle weakness and affected individuals report fatigue as one of their most disabling symptoms. Expiratory muscle strength was correlated with self-reported physical fatigue, while respiratory muscle endurance was correlated with functional performance and sleepiness. Respiratory muscle strength was not correlated with lung spirometry testing. These findings highlight the importance of considering the effects of respiratory muscle weakness when evaluating causes of fatigue among individuals with mild-to-moderate MS.

Effects of Different Types of Respiratory Muscle Training on Exercise Performance in Runners

To compare two different types of respiratory muscle training on exercise performance, a protocol was devised consisting of a combination of a 4-week, 12-session resistive respiratory muscle training (RRMT) followed by a 4-week, 12-session voluntary isocapnic hyperpnea training (VIHT) and conducted in experienced runners (4 men, 4 women). Measurements before and 5 days after training included: pulmonary function (spirometry), maximal inspiratory and expiratory mouth pressures, respiratory endurance time, maximal oxygen uptake (V(o2)max), running time to voluntary exhaustion at 80% V(o2)max, blood lactate concentration, and minute ventilation. There were no statistically significant differences in pulmonary functions and V(o2)max post-RRMT and post-VIHT compared to pre-RMT. Following RRMT the inspiratory muscle strength had improved by 23.8 +/- 30% and 18.7 +/- 21.4% at rest and immediately after the running test, respectively. RRMT did not increase the time intense voluntary isocapnic ventilation could be maintained during rest while VIHT increased it (237 +/- 207.8%). The duration of the endurance run was extended 17.7 +/- 6.5% after RRMT and 45.5 +/- 14.3% after VIHT.

Nutritional Intake Correlates with Function in Persons with Mild-to-Moderate Multiple Sclerosis

Background We sought to assess the associations between nutrition and ambulation, daily activity, quality of life (QOL), and fatigue in individuals with mild-to-moderate disability with multiple sclerosis (MS). Methods This cross-sectional pilot study included 20 ambulatory adult volunteers with MS (14 women and 6 men; mean ± SD age, 57.9 ± 10.2 years; mean ± SD Expanded Disability Status Scale score = 4.1 ± 1.8). Primary outcome variables included dietary assessment and the 6-Minute Walk Test (6MWT). Secondary measures included the Timed 25-Foot Walk test, Timed Up and Go test, daily activity, and three self-report questionnaires: the 12-item Multiple Sclerosis Walking Scale, the 36-item Short Form Health Survey (SF-36), and the Modified Fatigue Impact Scale. Results Significant correlations were seen between the percentage of diet comprising fats and the 6MWT (r = 0.51, P = .02) and the physical functioning component of the SF-36 (r = 0.47, P = .03). The percentage of carbohydrates was significantly correlated with the 6MWT (r = -0.43, P = .05), daily activity (r = -0.59, P = .005), and the physical functioning component of the SF-36 (r = -0.47, P = .03). Cholesterol, folate, iron, and magnesium were significantly positively correlated with the physical functioning component of the SF-36 and the 6MWT. Conclusions These findings indicate better ambulation, daily function, and QOL with increased fat intake, decreased carbohydrate intake, and increased intake of the micronutrients cholesterol, folate, iron, and magnesium in people with mild-to-moderate MS. This pilot study highlights the potential impact of diet on function and QOL in MS.

Lifetime physical inactivity is associated with lung cancer risk and mortality

INTRODUCTION Investigations of the independent associations of physical inactivity with cancer endpoints have been mounting in the epidemiological literature, in part due to the high prevalence of physical inactivity among cancer patients and to evidence that inactivity associates with carcinogenesis via pathways independent of obesity. Yet, physical inactivity is not currently recognized as a well-established risk or prognostic factor for lung cancer. As such, we examined the associations of lifetime physical inactivity with lung cancer risk and mortality in a hospital-based, case-control study. PRESENTATION OF CASE Materials and Methods: The analyses included data from 660 lung cancer patients and 1335 matched cancer-free controls. Multivariable logistic regression analyses were utilized to assess the association between lifetime physical inactivity and lung cancer risk, and Cox proportional hazards models were utilized to estimate the association between lifetime physical inactivity and mortality among lung cancer cases.Results: We observed a significant positive association between lifetime physical inactivity and lung cancer risk: [Odds ratio (OR)=2.23, 95% confidence interval (CI): 1.77-2.81]; the association remained significant among never smokers (OR=3.00, 95% CI:1.33-6.78) and non-smokers (OR=2.33, 95% CI: 1.79-3.02). We also observed a significant positive association between lifetime physical inactivity and lung cancer mortality [Hazard ratio (HR)=1.40, 95% CI: 1.14-1.71]; the association remained significant in non-smokers (HR=1.51, 95% CI: 1.16-1.95). DISCUSSION/CONCLUSION These data add to the body of evidence suggesting that physical inactivity is an independent risk and prognostic factor for cancer. Additional research utilizing prospectively collected data is needed to substantiate the current findings.

Vitamin D3 intake modulates diaphragm but not peripheral muscle force in young mice

Recent data support an important role for vitamin D in respiratory health. We tested the hypothesis that dietary vitamin D3 (VD3) intake modulates diaphragm (DIA) strength. Four-week-old female A/J mice (n = 10/group) were randomized to receive diets containing 100 IU VD3/kg (low), 1,000 IU VD3/kg (reference), or 10,000 IU VD3/kg (pharmacologic). After 6 wk of dietary intervention, plasma 25-hydroxyvitamin D3 (25D3) levels, DIA and extensor digitorum longus (EDL) in vitro contractile properties, and fiber cross-sectional area (CSA) were measured. Myosin heavy chain (MHC) composition and Akt/Foxo3A growth signaling were studied in the DIA and tibialis anterior. Mice fed the low, reference, and pharmacologic diets had average 25D3 levels of 7, 21, and 59 ng/ml, respectively. Maximal DIA force, twitch force, and fiber CSA were reduced 26%, 28%, and 10% (P < 0.01), respectively, in mice receiving the low-VD3 diet compared with the reference and pharmacologic diets. EDL force parameters were unaltered by diet. Effects of VD3 intake on DIA force were not observed in mice that began dietary intervention at 12 wk of age. VD3 intake did not alter the MHC composition of the DIA, indicating that decreases in force and CSA in young mice were not due to a switch in fiber type. Paradoxically, low VD3 intake was associated with activation of anabolic signaling in muscle (hyperphosphorylation of Akt and Foxo3A and decreased expression of autophagy marker LC3). These studies identify a potential role of dietary VD3 in regulating DIA development and insulin sensitivity.