Greg D. Wells

Non-invasive prospective targeting of arterial P(CO2) in subjects at rest.

Accurate measurements of arterial P  CO 2 (P  a,CO 2 ) currently require blood sampling because the end‐tidal P  CO 2 (P  ET,CO 2 ) of the expired gas often does not accurately reflect the mean alveolar P  CO 2 and P  a,CO 2. Differences between P  ET,CO 2 and P  a,CO 2 result from regional inhomogeneities in perfusion and gas exchange. We hypothesized that breathing via a sequential gas delivery circuit would reduce these inhomogeneities sufficiently to allow accurate prediction of P  a,CO 2 from P  ET,CO 2. We tested this hypothesis in five healthy middle‐aged men by comparing their P  ET,CO 2 values with P  a,CO 2 values at various combinations of P  ET,CO 2 (between 35 and 50 mmHg), P  O 2 (between 70 and 300 mmHg), and breathing frequencies (f; between 6 and 24 breaths min−1). Once each individual was in a steady state, P  a,CO 2 was collected in duplicate by consecutive blood samples to assess its repeatability. The difference between P  ET,CO 2 and average P  a,CO 2 was 0.5 ± 1.7 mmHg (P= 0.53; 95% CI −2.8, 3.8 mmHg) whereas the mean difference between the two measurements of P  a,CO 2 was −0.1 ± 1.6 mmHg (95% CI −3.7, 2.6 mmHg). Repeated measures ANOVAs revealed no significant differences between P  ET,CO 2 and P  a,CO 2 over the ranges of P  O 2, f and target P  ET,CO 2. We conclude that when breathing via a sequential gas delivery circuit, P  ET,CO 2 provides as accurate a measurement of P  a,CO 2 as the actual analysis of arterial blood.

Remote preconditioning improves maximal performance in highly trained athletes.

BACKGROUND Remote ischemic preconditioning (RIPC) induced by transient limb ischemia releases a dialysable circulating protective factor that reduces ischemia-reperfusion injury. Exercise performance in highly trained athletes is limited by tissue hypoxemia and acidosis, which may therefore represent a type of ischemia-reperfusion stress modifiable by RIPC. METHODS AND RESULTS National-level swimmers, 13-27 yr, were randomized to RIPC (four cycles of 5-min arm ischemia/5-min reperfusion) or a low-pressure control procedure, with crossover. In study 1, subjects (n=16) performed two incremental submaximal swimming tests with measurement of swimming velocity, blood lactate, and HR. For study 2, subjects (n=18) performed two maximal competitive swims (time trials). To examine possible mechanisms, blood samples taken before and after RIPC were dialysed and used to perfuse mouse hearts (n=10) in a Langendorff preparation. Infarct sizes were compared with dialysate obtained from nonathletic controls. RIPC released a protective factor into the bloodstream, which reduced infarct size in mice (P<0.05 for controls and swimmers). There was no statistically significant difference between the effect of RIPC and the low-pressure control protocol on submaximal exercise performance. However, RIPC was associated with a mean improvement of maximal swim time for 100 m of 0.7 s (P=0.04), an improvement in swim time relative to personal best time (-1.1%, P=0.02), and a significant improvement in average International Swimming Federation points (+22 points, P=0.01). CONCLUSIONS RIPC improves maximal performance in highly trained swimmers. This simple technique may be applicable to other sports and, more importantly, to other clinical syndromes in which exercise tolerance is limited by tissue hypoxemia or ischemia.

Exercise and physical activity in children with cystic fibrosis

Regular exercise and habitual physical activity are important for patients with cystic fibrosis (CF). Research has demonstrated the benefits of aerobic, anaerobic, and strength exercise training programs for health and quality of life, however, the CF patient is faced with unique barriers and challenges to participation. Recently, increased levels of habitual physical activity have been shown to slow the decline in lung function in patients with CF, and regular participation in a variety of activities may result in greater adherence in the long term. Research is now available to justify the incorporation of exercise into the routine care of patients with CF. This paper provides the background and rationale for the implementation of exercise and habitual physical activity recommendations by the health care team. Education of health care providers regarding the importance of exercise and habitual physical activity for patients with CF is needed in order for exercise and physical activity to be incorporated as key components of clinical practice and into the lives of patients with CF.

Skeletal muscle metabolic dysfunction in obesity and metabolic syndrome.

Obesity and the related metabolic syndrome have become a worldwide epidemic. Inactivity appears to be a primary causative factor in the pathogenesis of this obesity and metabolic syndrome. There are two possible, perhaps not mutually exclusive, events that may lead to intramyocellular lipid accumulation and mitochondrial dysfunction in patients with obesity. First, obesity, with high intake-associated lipid accumulation in muscle may interfere with cellular mitochondrial function through generation of reactive oxygen species leading to lipid membrane peroxidative injury and disruption of mitochondrial membrane-dependent enzymes. This in turn leads to impaired oxidative metabolism. Secondly, a primary defect in mitochondrial oxidative metabolism may be responsible for a reduction in fatty acid oxidation leading to intramyocellular lipid accumulation as a secondary event. Non-invasive techniques such as proton (1H) and phosphorus (31P) magnetic resonance spectroscopy, coupled with specific magnetic resonance imaging techniques, may facilitate the investigation of the effects of various ergometric interventions on the pathophysiology of obesity and the metabolic syndrome. Exercise has positive effects on glucose metabolism, aerobic metabolism, mitochondrial density, and respiratory chain proteins in patients with metabolic syndrome, and we propose that this may be due to the exercise effects on AMP kinase, and a prospective physiological mechanism for this benefit is presented. A physiological model of the effect of intramyocellular lipid accumulation on oxidative metabolism and insulin mediated glucose uptake is proposed.

Reliability and validity of the habitual activity estimation scale (HAES) in patients with cystic fibrosis

To understand potential benefits of exercise in the cystic fibrosis (CF) population, there needs to be accurate methods to quantify it. The Habitual Activity Estimation Scale (HAES) questionnaire has been shown to be a feasible tool to measure physical activity however the reliability and validity have yet to be determined in the CF population.

Skeletal Muscle Metabolism in Cystic Fibrosis and Primary Ciliary Dyskinesia

Previous studies have reported differences in muscle function and metabolism between patients with cystic fibrosis (CF) and healthy controls (HC), but it is currently unknown whether these abnormalities are specific to CF or also seen in other airway diseases. In this study, we used magnetic resonance spectroscopy (MRS) during exercise to assess muscle metabolism in CF patients. Twenty patients with CF and 20 age, gender, and habitual activity-matched HCs and a respiratory disease comparison group with primary ciliary dyskinesia (PCD; n = 10) were studied. 31Phosphorus MRS (31P-MRS) was used to characterize muscle bioenergetic metabolism at rest and after high-, moderate-, and low-intensity exercise. CF patients exhibited lower resting ATP/phosphocreatine (PCr) ratio and significantly higher end-exercise pH values compared with both HC and PCD patients. Both CF and PCD patients demonstrated significantly slower PCr recovery time constants after high-intensity exercise. Our results suggest that not only there are specific abnormalities of muscle metabolism in CF patients but also there is a nonspecific impact of respiratory disease on muscle function.

Longitudinal Relationship between Physical Activity and Lung Health in Patients with Cystic Fibrosis

Exercise is beneficial for patients with cystic fibrosis (CF) but long-term effects of physical activity on lung function evolution are unknown. We evaluated the longitudinal relationship between changes in habitual physical activity (HPA) and rate of decline in lung function in patients with CF. We tracked HPA using the Habitual Activity Estimation Scale, forced expiratory volume in 1 s (FEV1) and Stage I exercise tests in 212 patients with CF over a 9-year period. Adjusting for sex, baseline age and FEV1, mucoid Pseudomonas aeruginosa and CF-related diabetes, mean±sd FEV1 % predicted decreased by 1.63±0.08% per year (p<0.0001) while mean±sd HPA increased by 0.28±0.03 h·day−1 per year (p<0.0001) over the study period. A greater increase in HPA was associated with a slower rate of decline in FEV1 (r=0.19, p<0.0069). Dividing subjects into “high” and “low” activity (above or below the mean rate of change of activity, respectively), a steeper rate of FEV1 decline was observed for low (-1.90% per year) compared to high (-1.39% per year) (p=0.002). Increases in HPA are feasible despite progression of lung disease and are associated with a slower rate of decline in FEV1, highlighting the benefit of regular physical activity, and its positive impact on lung function in patients with CF. FEV1 declines at a lesser rate in patients with cystic fibrosis who increase their activity levels http://ow.ly/rETZc

Acculturation in elite sport: a thematic analysis of immigrant athletes and coaches

Abstract To identify key issues concerning the acculturation of immigrant athletes in sport psychology, a thematic analysis (Braun & Clarke, 2006) was conducted on focus group interview data from immigrant elite athletes relocated to Canada (n = 13) and coaches working with such athletes (n = 10). Two central themes were identified: (a) navigating two world views which referred to acculturation as a fluid process where athletes navigated between cultural norms of the home community and the host community, and (b) acculturation loads, which referred to whether immigrants and those in the host country shared acculturation (i.e., acculturation as a two-way process) or managed the load with or without support from others (i.e., acculturation as one-directional). Each of these central themes comprised sub-themes, which provided further insight into the experiences of acculturation for immigrant elite athletes. From the project, the authors recommend further research utilising case studies to provide a holistic description of the acculturation process from the vantage of various people within the sport context.

Physical activity prescription: a critical opportunity to address a modifiable risk factor for the prevention and management of chronic disease: a position statement by the Canadian Academy of Sport and Exercise Medicine

Non-communicable disease is a leading threat to global health. Physical inactivity is a large contributor to this problem; in fact, the WHO ranks it as the fourth leading risk factor for overall morbidity and mortality worldwide. In Canada, at least 4 of 5 adults do not meet the Canadian Physical Activity Guidelines of 150 min of moderate-to-vigorous physical activity per week. Physicians play an important role in the dissemination of physical activity (PA) recommendations to a broad segment of the population, as over 80% of Canadians visit their doctors every year and prefer to get health information directly from them. Unfortunately, most physicians do not regularly assess or prescribe PA as part of routine care, and even when discussed, few provide specific recommendations. PA prescription has the potential to be an important therapeutic agent for all ages in primary, secondary and tertiary prevention of chronic disease. Sport and exercise medicine (SEM) physicians are particularly well suited for this role and should collaborate with their primary care colleagues for optimal patient care. The purpose of this Canadian Academy and Sport and Exercise Medicine position statement is to provide an evidence-based, best practices summary to better equip SEM and primary care physicians to prescribe PA and exercise, specifically for the prevention and management of non-communicable disease. This will be achieved by addressing common questions and perceived barriers in the field. Author note This position statement has been endorsed by the following nine sport medicine societies: Australasian College of Sports and Exercise Physicians (ACSEP), American Medical Society for Sports Medicine (AMSSM), British Association of Sports and Exercise Medicine (BASEM), European College of Sport & Exercise Physicians (ECOSEP), Norsk forening for idrettsmedisin og fysisk aktivite (NIMF), South African Sports Medicine Association (SASMA), Schweizerische Gesellschaft für Sportmedizin/Swiss Society of Sports Medicine (SGSM/SSSM), Sport Doctors Australia (SDrA), Swedish Society of Exercise and Sports Medicine (SFAIM), and CASEM.

The Effects of Beta-Alanine Supplementation on Performance: A Systematic Review of the Literature

PURPOSE To critically review the methodological quality and synthesize information from systematic reviews and high quality studies on the effects of beta alanine (BA) on exercise and athletic performance. METHODS A search strategy was developed in accordance with the standards for the reporting of scientific literature via systematic reviews. Five databases were thoroughly searched from inception to November 2012. Inclusion criteria were English language, human studies, used BA to increase exercise or athletic performance, systematic reviews or randomized controlled trials and were published in a peer-reviewed journal. Included studies were systematically graded for their methodological quality by rotating pairs of reviewers and the results were qualitatively synthesized. RESULTS One systematic review and 19 randomized trials were included in this review. There is one systematic review with several methodological weaknesses that limit the confidence in its results. There are moderate to high quality studies that appear to support that BA may increase power output and working capacity, decrease the feeling of fatigue and exhaustion, and have of positive effect on body composition and carnosine content. The reporting of side effects from BA supplementation in the athletic population was generally under-reported. CONCLUSIONS There appears to be some evidence from this review that supplementation with BA may increase athletic performance. However, there is insufficient evidence examining the safety of BA supplementation and its side effects. It is therefore recommended to err on the side of caution in using BA as an ergogenic aid until there is sufficient evidence confirming its safety.