The functioning of the diaphragms of the patients with stable COPD is as good as in normal subjects at the same lung volume. Compensatory phenomena appear to counterbalance the deleterious effects of hyperinflation on the contractility and inspiratory action of the diaphragm in patients with COPD. Our findings cast doubt on the existence of chronic fatigue of the diaphragm in such patients and therefore on the need for therapeutic interventions aimed at improving diaphragm function.

The ability of the diaphragm to generate pressures at different lung volumes (VLs) in humans may be determined by the following factors: 1) its in vivo three-dimensional shape, radius of curvature, and tension according to Laplace law; 2) the relative degree to which it is apposed to the rib cage (i.e., zone of apposition) and lungs (i.e., diaphragm dome); and 3) its length-force properties. To gain more insight into these factors we have reconstructed from nuclear magnetic images the three-dimensional shape of the diaphragm of four normal subjects under supine relaxed conditions at four different VLs: residual volume, functional residual capacity, functional residual capacity plus one-half of the inspiratory capacity, and total lung capacity. Under our experimental conditions the shape of the diaphragm changes substantially in the anteroposterior plane but not in the coronal one. Multivariate regression analysis indicates that the zone of apposition is dependent on both diaphragm shortening and lower rib cage widening with lung inflation, although much more on the first of these two factors. Because of the changes in anteroposterior shape and expansion of the insertional origin at the costal margin with lung inflation, the data therefore suggest that the diaphragm may be more accurately modeled by a "widening piston" (Petroll's model) than a simple "piston in a cylinder" model. A significant portion of the muscular surface is lung apposed, suggesting that diaphragmatic force has radial vectors in the dome and vectors along the body axis in the zone of apposition. The muscular surface area of the diaphragm decreased linearly by approximately 41% with VL from residual volume to total lung capacity. Diaphragmatic fibers may shorten under physiological conditions more than any other skeletal muscle. The large changes in fiber length combined with limited shape changes with lung inflation suggest that the length-twitch force properties of the diaphragm may be the most important factor for the pressure-generating function of this respiratory muscle in response to bilateral phrenic shocks at different VLs.

Objective To evaluate the effectiveness of a nurse-led hospital-to-home transitional care intervention versus usual care on mental functioning (primary outcome), physical functioning, depressive symptoms, anxiety, perceived social support, patient experience, and health service use costs in older adults with multimorbidity (≥ 2 comorbidities) and depressive symptoms. Design and setting Pragmatic multi-site randomized controlled trial conducted in three communities in Ontario, Canada. Participants were allocated into two groups of intervention and usual care (control). Participants 127 older adults (≥ 65 years) discharged from hospital to the community with multimorbidity and depressive symptoms. Intervention This evidence-based, patient-centred intervention consisted of individually tailored care delivery by a Registered Nurse comprising in-home visits, telephone follow-up and system navigation support over 6-months. Outcome measures The primary outcome was the change in mental functioning, from baseline to 6-months. Secondary outcomes were the change in physical functioning, depressive symptoms, anxiety, perceived social support, patient experience, and health service use cost, from baseline to 6-months. Intention-to-treat analysis was performed using ANCOVA modeling. Results Of 127 enrolled participants (63-intervention, 64-control), 85% had six or more chronic conditions. 28 participants were lost to follow-up, leaving 99 (47 -intervention, 52-control) participants for the complete case analysis. No significant group differences were seen for the baseline to six-month change in mental functioning or other secondary outcomes. Older adults in the intervention group reported receiving more information about health and social services (p = 0.03) compared with the usual care group. Conclusions Although no significant group differences were seen for the primary or secondary outcomes, the intervention resulted in improvements in one aspect of patient experience (information about health and social services). The study sample fell below the target sample (enrolled 127, targeted 216), which can account for the non-significant findings. Further research on the impact of the intervention and factors that contribute to the results is recommended. Trial registration clinicaltrials.gov Identifier: NCT03157999.

We evaluated the effect of global inspiratory muscle fatigue (GF) on respiratory muscle control during exercise at 30, 60, and 90% of maximal power output in normal subjects. Fatigue was induced by breathing against a high inspiratory resistance until exhaustion. Esophageal and gastric pressures, anteroposterior displacement of the rib cage and abdomen, breathing pattern, and perceived breathlessness were measured. Induction of GF had no effect on the ventilatory parameters during mild and moderate exercise. It altered, however, ventilatory response to heavy exercise by increasing breathing frequency and minute ventilation, with minor changes in tidal volume. This was accompanied by an increase in perceived breathlessness. GF significantly increased both the tonic and phasic activities of abdominal muscles that allowed 1) the diaphragm to maintain its function while developing less pressure, 2) the same tidal volume with lesser shortening of the rib cage inspiratory muscles, and 3) relaxation of the abdominal muscles to contribute to lung inflation. The increased work performed by the abdominal muscles may, however, lead to a reduction in their strength. GF may impair exercise performance in some healthy subjects that is probably not related to excessive breathlessness or other ventilatory factors. We conclude that the respiratory system is remarkably adaptable in maintaining ventilation during exercise even with impaired inspiratory muscle contractility.

Background:The International Physical Activity Questionnaire (IPAQ) has received significant attention since the late 1990s. As it currently stands, its long version has been translated in English, German, Icelandic, Korean, Polish, Spanish, Turkish, and Vietnamese. However no data originating from the self-administered long version (last 7 days) of the IPAQ (IPAQ-SALV) is available for French Canadians. This study developed a self-administered long version (last 7 days) of the IPAQ in Canadian French (IPAQ-SALVCF) and assessed its psychometric properties.Methods:The original IPAQ-SALV was linguistically translated, back-translated, and then reviewed in a focus group to ensure its meaning had been retained. Data were collected on a sample of 34 Francophones from Northern Ontario, and the results compared with step counts assessed by 7-day pedometer recording. Test-retest reliability was examined with a 24-hour delay between questionnaire completion on day 8 and day 9 of the protocol. Convergent validity was assessed by comparing IPAQ-SALVCF (last 7 days) results to average step counts over a 7-day period.Results:Intra-class correlation coefficients (ICC) revealed that the IPAQ-SALVCF results were stable between days. The ICC for total activity scores was highest at 0.93 (CI: 0.86 to 0.97). Total activity scores were also significantly related to pedometer step counts (Pearson r = .66 P < .01). These results confirm those obtained in prior researchConclusion:The IPAQ-SALVCF is a reliable and valid measure of physical activity for French Canadians.

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Cultural sport psychology (CSP) is a recent attempt by researchers to better understand respondents from marginalized cultures. CSP research provides useful suggestions of how to work effectively with unique populations for coaches and sport science practitioners. This paper addresses the struggles and adaptation strategies of 23 (16 male, 7 female) elite Aboriginal Canadian athletes. National and international level athletes elicited from seven sport disciplines and three Canadian provinces were interviewed with a semistructured protocol. Indications are that Aboriginal Canadian athletes engage in two higher order types of adaptation: (a) self-adaptation and (b) adapted environment. The study was developed, analyzed, and coauthored with an Aboriginal community appointed research team. Implications, such as the use of ongoing reflective practice, are proposed for aspiring CSP sport researchers and practitioners.

These results do not support claims that the BSD offers increased physical activity. In fact, these results suggest that students enrolled in schools using the BSD schedule may have reduced daily physical activity. In addition, these results demonstrate that overall school-based physical activity is less than half of the recommended level; independent of school scheduling.