Biventricular responses to exercise and their relation to cardiorespiratory fitness in pediatric pulmonary hypertension.

Despite exercise intolerance being predictive of outcomes in pulmonary arterial hypertension (PAH), its underlying cardiac mechanisms are not well described. The aim of the study was to explore the biventricular response to exercise and its associations with cardiorespiratory fitness in children with PAH. Participants underwent incremental cardio-pulmonary exercise testing and simultaneous exercise echocardiography on a recumbent cycle ergometer. Linear mixed models were used to assess cardiac function variance and associations between cardiac and metabolic parameters during exercise. Eleven participants were included with a mean age 13.4 ±2.9 years. Right ventricle (RV) systolic pressure (RVsp) increased from a mean of 59 ±25 mmHg at rest to 130 ±40 mmHg at peak exercise (p<0.001), while RV fractional area change (RV-FAC) and RV free wall longitudinal strain (RVFW-Sl) worsened (35.2% vs 27%, p=0.09 and -16.6% vs -14.6%, p=0.1, respectively). At low and moderate intensity exercise, RVsp was positively associated with stroke volume and O2 pulse (p<0.1). At high intensity exercise RV-FAC, RVFW-Sl and left ventricular longitudinal strain were positively associated with oxygen uptake and O2 pulse (p<0.1), while stroke volume decreased towards peak (p=0.04). In children with PAH, the increase of pulmonary pressure alone does not limit peak exercise, but rather the concomitant reduced RV functional reserve, resulting in RV-PA uncoupling, worsening of inter-ventricular interaction and LV dysfunction. A better mechanistic understanding of PAH exercise physiopathology can inform stress testing and cardiac rehabilitation in this population.

Physiological stress reactivity in pediatric cancer survivors treated with chemotherapy.

Children who experience early life stress demonstrate changes to their stress responses, which may modulate long-term health. Childhood cancer presents significant stress during diagnosis, treatment, and survivorship. We hypothesized that children who have completed chemotherapy treatment for ALL will demonstrate altered hormone patterns in response to a stressor compared with healthy controls. Twelve pediatric ALL survivors and 12 healthy controls completed the Trier Social Stress Test. Salivary samples, heart rate, and self-report ratings of stress were collected at baseline, pretest, and posttest. Between group comparison showed baseline (interleukin [IL]-8) was significantly higher in the survivor group versus controls (survivors: 89.9, 40.1-544.9 pg ml-1 ; controls: 30.7, 5.6-241.9 pg ml-1 , p = .001) as was peak (IL-8) (survivors: 147.1, 71.6-1177.6 pg ml-1 ; controls: 75.5, 28.6-698.6 pg ml-1 ). Peak salivary alpha-amylase (sAA) concentration was significantly lower in the survivor group (survivors: 69.3, 19.4-195.5 U ml-1 ; controls: 91.2, 27.7-213.7 U ml-1 ; p = .04). Repeated measures ANOVA revealed significant main effects for time on cortisol (F(2.35, 50.81)  = 5.9, p < .01), sAA (F(1.56, 33.17)  = 6.6, p < .01), stress ratings (F(3.42, 88.14)  = 53.4, p < .001), and heart rate (F(8, 83)  = 16.8, p < .05). Significant main effects for group were observed for IL-8 (F(1, 23)  = 8.2, p < .01) and tumor necrosis factor-α (F(1, 23)  = 6.8, p < .05). Significant interaction effects for group × time were found for sAA (F(5, 106)  = 2.8, p < .05). Our results indicate that childhood ALL survivors have similar responses to stress as healthy controls, but lower sympatho-adrenal-medullary reactivity. Therefore, altered stress regulation may present a pathway modulating long-term health in this population.

Peripheral Skeletal Muscle Impairment in Children After Treatment for Leukemia and Lymphoma.

Exercise intolerance is a common adverse effect of childhood cancer, contributing to impaired health and well-being. While reduced aerobic fitness has been attributed to central cardiovascular deficiencies, the involvement of peripheral musculature has not been investigated. We studied peripheral muscle function in children following cancer treatment using noninvasive phosphorus-31 magnetic resonance spectroscopy. Ten acute lymphoblastic leukemia (ALL) and 1 lymphoma patient 8 to 18 years of age who completed treatment 6 to 36 months prior and 11 healthy controls participated in the study. Phosphorus-31 magnetic resonance spectroscopy was used to characterize muscle bioenergetics at rest and following an in-magnet knee-extension exercise. Exercise capacity was evaluated using a submaximal graded treadmill test. Both analysis of variance and Cohen d were used as statistical methods to determine the statistical significance and magnitude of differences, respectively, on these parameters between the patient and control groups. The patients treated for ALL and lymphoma exhibited lower anaerobic function ( P =0.14, d =0.72), slower metabolic recovery ( P =0.08, d =0.93), and lower mechanical muscle power ( d =1.09) during exercise compared with healthy controls. Patients demonstrated lower estimated VO 2peak (41.61±5.97 vs. 47.71±9.99 mL/min/kg, P =0.11, d =0.76), lower minutes of physical activity (58.3±35.3 vs. 114.8±79.3 min, P =0.12, d =0.99) and higher minutes of inactivity (107.3±74.0 vs. 43.5±48.3 min, d =1.04, P <0.05). Children treated for ALL and lymphoma exhibit altered peripheral skeletal muscle metabolism during exercise. Both deconditioning and direct effects of chemotherapy likely contribute to exercise intolerance in this population.

The Exeter Activity Unlimited statement on physical activity and exercise for cystic fibrosis: methodology and results of an international, multidisciplinary, evidence-driven expert consensus.

BACKGROUND: The roles of physical activity (PA) and exercise within the management of cystic fibrosis (CF) are recognised by their inclusion in numerous standards of care and treatment guidelines. However, information is brief, and both PA and exercise as multi-faceted behaviours require extensive stakeholder input when developing and promoting such guidelines. METHOD: On 30th June and 1st July 2021, 39 stakeholders from 11 countries, including researchers, healthcare professionals and patients participated in a virtual conference to agree an evidence-based and informed expert consensus about PA and exercise for people with CF. This consensus presents the agreement across six themes: (i) patient and system centred outcomes, (ii) health benefits, iii) measurement, (iv) prescription, (v) clinical considerations, and (vi) future directions. The consensus was achieved by a stepwise process, involving: (i) written evidence-based synopses; (ii) peer critique of synopses; (iii) oral presentation to consensus group and peer challenge of revised synopses; and (iv) anonymous voting on final proposed synopses for adoption to the consensus statement. RESULTS: The final consensus document includes 24 statements which surpassed the consensus threshold (>80% agreement) out of 30 proposed statements. CONCLUSION: This consensus can be used to support health promotion by relevant stakeholders for people with CF.

The Impact of Moderate and High Intensity Cardiovascular Exertion on Sub-Elite Soccer Referee's Cognitive Performance: A Lab-Based Study.

Soccer referees represent a specialized population who are required to perform decisional or perceptual tasks during physical exertion. Recent studies have demonstrated that submaximal acute exercise has a positive impact on cognitive performance. However, less is known about the impact of more strenuous exertion on cognitive performance. This study assessed the effect of moderate and maximal intensity exercise exertion on a cognitive performance in sub-elite soccer referees. Twelve experienced soccer referees (4 female, 8 male) were recruited. Data were collected on 2 separate days. Baseline fitness level was assessed by a standardized aerobic capacity test (VO2max Test) on Day 1, along with practice trials of the Stroop Color Word Test (Stroop Test) for evaluating cognitive performance. On Day 2, cognitive performance was assessed before, during, and after an incremental intensity exercise protocol based on the Fédération International de Football Association (FIFA) referee fitness test. Relative to results obtained at rest performance on the Stroop Test improved at moderate exertion and at maximal exertion during the modified FIFA fitness test (F = 18.97, p = .005). Mean time to completion (in seconds) of the interference Stroop task significantly improved (p < .05) between rest and moderate exertion [-3.0 ± 3.0 seconds] and between rest and maximal exertion [-4.8 ± 2.6 seconds]. In summary, we observed that cognitive performance was found to improve when sub-elite soccer referees performed moderate and maximal exercise relative to results obtained at rest. It is possible that referees focus their attention to improve goal-oriented processing in the brain during physical exertion.

Uterine artery and umbilical vein blood flow are unaffected by moderate habitual physical activity during pregnancy.

OBJECTIVE: This study aims to noninvasively quantify blood flow in the uterine arteries (UTAs) and umbilical vein (UV) using phase-contrast magnetic resonance imaging (PC-MRI) and test whether these correlate with maternal fitness parameters. METHOD: Resting UTA and UV flows were measured in 23 healthy 30 ± 3-year-old women who engaged in moderate-intensity physical activity during pregnancy. Participant fitness was characterized in the second and third trimesters using the submaximal oxygen uptake (VO2 ) test measuring heart rate (HR), VO2 , ventilation (ventilatory equivalent [VE]/VO2 ), and the Borg rating of perceived exertion (respiratory quotient [RQ]). Linear regression models were used to determine the associations between blood flow and maternal fitness measures. RESULTS: Blood flows in the UTA (957 ± 241 mL/min) and UV (132 ± 38 mL/min/kg) were successfully measured in 20 (87%) participants. Neither was associated with any physical fitness parameters (HR, VO2 , VE/VO2 , and RQ) nor with any second-to-third trimester change in these parameters. CONCLUSION: PC-MRI can be used to noninvasively measure blood flow in the UTA and UV. Neither resting UTA nor UV flow is associated with maternal fitness parameters. This is the first MRI-based study to provide novel hemodynamic data suggesting decoupling between maternal moderate fitness level and the maternal-placental-fetal hemodynamic system in healthy, normal body mass index (BMI) pregnancies.

Physical activity for children with chronic disease; a narrative review and practical applications.

BACKGROUND: Physical activity (PA) is associated with a diverse range of health benefits. International guidelines suggest that children should be participating in a minimum of 60 min of moderate to vigorous intensity PA per day to achieve these benefits. However, current guidelines are intended for healthy children, and thus may not be applicable to children with a chronic disease. Specifically, the dose of PA and disease specific exercise considerations are not included in these guidelines, leaving such children with few, if any, evidence-based informed suggestions pertaining to PA. Thus, the purpose of this narrative review was to consider current literature in the area of exercise as medicine and provide practical applications for exercise in five prevalent pediatric chronic diseases: respiratory, congenital heart, metabolic, systemic inflammatory/autoimmune, and cancer. METHODS: For each disease, we present the pathophysiology of exercise intolerance, summarize the pediatric exercise intervention research, and provide PA suggestions. RESULTS: Overall, exercise intolerance is prevalent in pediatric chronic disease. PA is important and safe for most children with a chronic disease, however exercise prescription should involve the entire health care team to create an individualized program. CONCLUSIONS: Future research, including a systematic review to create evidence-based guidelines, is needed to better understand the safety and efficacy of exercise among children with chronic disease.

Skeletal Muscle Metabolic Dysfunction in Patients With Malignant Hyperthermia Susceptibility.

BACKGROUND: Malignant hyperthermia (MH), a pharmacogenetic disorder of skeletal muscle, presents with a potentially lethal hypermetabolic reaction to certain anesthetics. However, some MH-susceptible patients experience muscle weakness, fatigue, and exercise intolerance in the absence of anesthetic triggers. The objective of this exploratory study was to elucidate the pathophysiology of exercise intolerance in patients tested positive for MH with the caffeine-halothane contracture test. To this end, we used phosphorus magnetic resonance spectroscopy, blood oxygen level-dependent functional magnetic resonance imaging (MRI), and traditional exercise testing to compare skeletal muscle metabolism in MH-positive patients and healthy controls. METHODS: Skeletal muscle metabolism was assessed using phosphorus magnetic resonance spectroscopy and blood oxygen level-dependent functional MRI in 29 MH-positive patients and 20 healthy controls. Traditional measures of physical capacity were employed to measure aerobic capacity, anaerobic capacity, and muscle strength. RESULTS: During 30- and 60-second exercise, MH-positive patients had significantly lower ATP production via the oxidative pathway compared to healthy controls. MH-positive patients also had a longer recovery time with blood oxygen level-dependent functional MRI compared to healthy controls. Exercise testing revealed lower aerobic and anaerobic capacity in MH-positive patients compared to healthy controls. CONCLUSIONS: Results of this exploratory study suggest that MH-positive patients have impaired aerobic metabolism compared to healthy individuals. This could explain the exercise intolerance exhibited in MH-susceptible patient population.

Neuromuscular adaptations to sprint interval training and the effect of mammalian omega-3 fatty acid supplementation.

PURPOSE: Sprint interval training (SIT) stimulates rapid metabolic adaptations within skeletal muscle but the nature of neuromuscular adaptions is unknown. Omega-3 polyunsaturated fatty acids (N-3 PUFA) are suggested to enhance neuromuscular adaptations to exercise. METHODS: We measured the neuromuscular adaptations to SIT (Study-1) and conducted a placebo-controlled randomized double blinded study to determine the effect of N-3 PUFA supplementation on neuromuscular adaptations to SIT (Study-2). In Study-1, seven active men (24.4 ± 2.6 years, VO2 peak 43.8 ± 8.7 ml kg min-1) completed 2-weeks of SIT with pre- and post-training 10 km cycling time trials (TT). In Study-2, 30 active men (24.5 ± 4.2 years, VO2 peak 41.0 ± 5.1 ml kg min-1) were randomly assigned to receive N-3 PUFA (2330 mg day-1) (n = 14) or olive oil (n = 16) during 2-weeks of SIT with pre- and post-training TTs. Four week post-training, a SIT session and TT were also performed. Change in neuromuscular function was assessed from resting twitches, quadriceps maximal voluntary contraction (MVC) force, and potentiated twitch force (Q tw). RESULTS: Study-1 showed that SIT did not elicit significant neuromuscular adaptations. Study-2 showed that N-3 PUFA supplementation had no significant effect on neuromuscular adaptations. Training caused lower MVC force [mean ± SD; N-3 PUFA -9 ± 11%, placebo -9 ± 13% (p < 0.05 time)] and Q tw peripheral fatigue [N-3 PUFA -10 ± 19%, placebo -14 ± 13% (p < 0.05 time)]. TT time was lower after training in all groups [Study-1 -10%, Study-2 N-3 PUFA -8%, placebo -12% (p < 0.05 time)]. CONCLUSION: Two weeks of SIT improved TT performance in the absence of measurable neuromuscular adaptations. N-3 PUFA supplementation had no significant effect on SIT training adaptations.

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.

Exercise Intensity and Recovery: Biomarkers of Injury, Inflammation, and Oxidative Stress.

Biomarkers of inflammation, muscle damage, and oxidative stress after high-intensity exercise have been described previously; however, further understanding of their role in the postexercise recovery period is necessary. Because these markers have been implicated in cell signaling, they may be specifically related to the training adaptations induced by high-intensity exercise. Thus, a clear model showing their responses to exercise may be useful in characterizing the relative recovery status of an athlete. The purpose of this study was twofold: (a) to investigate the time course of markers of muscle damage and inflammation in the blood from 3 to 72 hours after combined training exercises and (b) to investigate indicators of oxidative stress and damage associated with increased reactive oxygen species production during high-intensity exercise in elite athletes. Nineteen male athletes performed a combination of high-intensity aerobic and anaerobic training exercises. Samples were acquired immediately before and at 3, 6, 12, 24, 48, and 72 hours after exercise. The appearance and clearance of creatine kinase and lactate dehydrogenase in the blood occurred faster than previous studies have reported. The neutrophil/lymphocyte ratio summarizes the mobilization of 2 leukocyte subpopulations in a single marker and may be used to predict the end of the postexercise recovery period. Further analysis of the immune response using serum cytokines indicated that high-intensity exercise performed by highly trained athletes only generated inflammation that was localized to the skeletal muscle. Biomarkers are not a replacement for performance tests, but when used in conjunction, they may offer a better indication of metabolic recovery status. Therefore, the use of biomarkers can improve a coach's ability to assess the recovery period after an exercise session and to establish the intensity of subsequent training sessions.

Characterizing blood oxygen level-dependent (BOLD) response following in-magnet quadriceps exercise.

OBJECT: There have been no studies to investigate the effects of cycling exercise protocols, as well as repeated bouts of exercise, on the blood oxygen level-dependent (BOLD) response in the quadriceps muscles. This study characterized BOLD signal recovery following non-ischemic bouts of exercise in the quadriceps muscles of healthy adults in order to provide a basis for application of a protocol for clinical populations. MATERIALS AND METHODS: Healthy male subjects (23.7 ± 2.0 years of age, n = 10) completed three cycles of one-minute exercise (65 % of maximum workload), with two minutes of rest between each bout, on an MRI-compatible ergometer. The BOLD responses during recovery were fitted to a sigmoid model, and response kinetics (post-exercise intensity [S0]), response time (α), change in baseline BOLD signal (κ), and inflection point (ß)] were measured. RESULTS: The sigmoid function fit well to the post-exercise BOLD data (r (2) = 0.95 ± 0.04). The mean response time was 10.5 ± 3.8 seconds, change in baseline BOLD intensity was 0.15 ± 0.068, and time to half-peak was 20.2 ± 8.6 seconds. CONCLUSION: The proposed sigmoid model is a robust method for quantifying quadriceps BOLD response post-exercise without induced ischemia. Extension of this model to evaluate microvascular responses in patients with chronic disease could improve our understanding of exercise intolerance.

The effect of on-hill active recovery performed between runs on blood lactate concentration and fatigue in alpine ski racers.

Alpine skiing is a high-intensity intermittent sport that results in lactate accumulation and muscle acidosis, which has been shown to contribute to peripheral neuromuscular fatigue. Active recovery influences the removal of lactate from the muscle and blood by maintaining blood flow to fatigued muscles and enhancing aerobic utilization of lactate by nonfatigued tissues. The purpose of this study was to investigate the effect of on-hill active recovery on blood lactate concentration in alpine skiers. Fourteen highly trained alpine skiers (7 women, 7 men) completed 8 training runs in a 45-gate slalom or a 25-gate giant slalom corridor at 2,600 m above sea level. Skiers were randomized to active (ACT) or static recovery (CON) performed at the top of each run. Blood lactate concentration and perceived fatigue were recorded at the top and bottom of each run. Performance was measured by time to complete each training run and rate of incomplete runs. A significant time (p < 0.01) and interaction (p = 0.001) effect was observed for blood lactate concentration measured at the top, with ACT being associated with significantly lower values. A significant time effect (p < 0.001) was observed for blood lactate concentration measured at the bottom. Training run completion time was longer (p ≤ 0.05), and higher rate of incomplete runs were observed in the CON group, despite no between-group differences in rating of perceived fatigue. On-hill active recovery performed between runs promotes blood lactate clearance in alpine skiers and is associated with delayed fatigue as indicated by faster training runs and fewer incomplete runs.

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.

The effect of various cold-water immersion protocols on exercise-induced inflammatory response and functional recovery from high-intensity sprint exercise.

PURPOSE: The purpose of this study was to investigate the effects of different cold-water immersion (CWI) protocols on the inflammatory response to and functional recovery from high-intensity exercise. METHODS: Eight healthy recreationally active males completed five trials of a high-intensity intermittent sprint protocol followed by a randomly assigned recovery condition: 1 of 4 CWI protocols (CWI-10 min × 20 °C, CWI-30 min × 20 °C, CWI-10 min × 10 °C, or CWI-30 min × 10 °C) versus passive rest. Circulating mediators of the inflammatory response were measured from EDTA plasma taken pre-exercise (baseline), immediately post-exercise, and at 2, 24, and 48 h post-exercise. Ratings of perceived soreness and impairment were noted on a 10-pt Likert scale, and squat jump and drop jump were performed at these time points. RESULTS: IL-6, IL-8, and MPO increased significantly from baseline immediately post-exercise in all conditions. IL-6 remained elevated from baseline at 2 h in the CWI-30 min × 20 °C, CWI-10 min × 10 °C, and CWI-30 min × 10 °C conditions, while further increases were observed for IL-8 and MPO in the CWI-30 min × 20 °C and CWI-30 min × 10 °C conditions. Squat jump and drop jump height were significantly lower in all conditions immediately post-exercise and at 2 h. Drop jump remained below baseline at 24 and 48 h in the CON and CWI-10 min × 20 °C conditions only, while squat jump height returned to baseline in all conditions. CONCLUSIONS: Cold-water immersion appears to facilitate restoration of muscle performance in a stretch-shortening cycle, but not concentric power. These changes do not appear to be related to inflammatory modulation. CWI protocols of excessive duration may actually exacerbate the concentration of cytokines in circulation post-exercise; however, the origin of the circulating cytokines is not necessarily skeletal muscle.

Exercise intolerance and the impact of physical activity in children treated with hematopoietic stem cell transplantation.

Hematopoietic stem-cell transplant (SCT) is increasingly used to treat children with cancer, and survival following SCT is improving. One predominant consequence of childhood cancer therapy is increased physical morbidity, which is worse in pediatric SCT recipients compared with children treated with chemotherapy or radiation alone. There are many factors that contribute to exercise intolerance and reduced physical function during the pretransplant, peritransplant, and posttransplant phases. These include side effects from chemotherapy or radiation, excessive immobility due to bed rest, infections, the negative effects of immunosuppressants, and graft vs host disease, all of which can impair cardiorespiratory fitness, muscle strength, and muscle function. Few studies have investigated the effects of exercise in childhood SCT recipients. In a small number of published studies, exercise interventions have been demonstrated to improve cardiorespiratory fitness, preserve or increase muscle mass, and improve muscle strength in children following SCT. The use of exercise as medicine may be a noninvasive and nonpharmaceutical treatment to target physical complications post-SCT. Researchers and health-care professionals should work together to develop exercise prescription guidelines for this unique and important population.

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.

Changes in vertebral artery blood flow following various head positions and cervical spine manipulation.

OBJECTIVE: The objective of the study was to investigate the cerebrovascular hemodynamic response of cervical spine positions including rotation and cervical spine manipulation in vivo using magnetic resonance imaging technology on the vertebral artery (VA). METHODS: This pilot study was conducted as a blinded examiner cohort with 4 randomized clinical tasks. Ten healthy male participants aged 24 to 30 years (mean, 26.8 years) volunteered to participate in the study. None of the participants had a history of disabling neck, arm, or headache pain within the last 6 months. They did not have any current or history of neurologic symptoms. In a neutral head position, physiologic measures of VA blood flow and velocity at the C1-2 spinal level were obtained using phase-contrast magnetic resonance imaging after 3 different head positions and a chiropractic upper cervical spinal manipulation. A total of 30 flow-encoded phase-contrast images were collected over the cardiac cycle, in each of the 4 conditions, and were used to provide a blood flow profile for one complete cardiac cycle. Differences between flow (in milliliters per second) and velocity (in centimeters per second) variables were evaluated using repeated-measures analysis of variance. RESULTS: The side-to-side difference between ipsilateral and contralateral VA velocities was not significant for either velocities (P = .14) or flows (P = .19) throughout the conditions. There were no other interactions or trends toward a difference for any of the other blood flow or velocity variables. CONCLUSIONS: There were no significant changes in blood flow or velocity in the vertebral arteries of healthy young male adults after various head positions and cervical spine manipulations.

An evaluation of early cardiometabolic risk factors in children and adolescents with Turner syndrome.

BACKGROUND AND OBJECTIVES: Turner syndrome (TS) confers increased lifetime risk of type 2 diabetes mellitus and cardiovascular disease. We compared cardiometabolic risk factors and measures of subcutaneous, visceral adipose tissue and intra-myocellular lipid between young TS girls and an age- and BMI-standard deviation scores (SDS)-matched healthy female cohort. PATIENTS AND METHODS: A cross-sectional cohort study was conducted at the Hospital for Sick Children, Toronto. Nineteen TS and 17 control girls (13.7 ± 2.5 vs 12.7 ± 3.4 years of age, respectively, P = 0.30). Multiple-sample oral glucose tolerance test with measurement of fasting insulin, LDL, HDL, triglycerides, adiponectin and highly sensitive C-reactive protein (hsCRP) was performed. Subcutaneous adipose tissue, visceral adipose tissue intramyocellular lipid levels evaluated by magnetic resonance techniques. Insulin secretion (IS), sensitivity (Si) and the insulin secretion-sensitivity index (ISSI-2) were calculated from oral glucose tolerance test data. RESULTS: Five TS and no controls had impaired fasting glucose or impaired glucose tolerance; none had type 2 diabetes mellitus. Insulin sensitivity and insulin secretion were similar between groups; ISSI-2 was lower in TS (923.5 ± 307.3 vs 659.1 ± 387.3; P = 0.03). TS girls had higher blood pressure (82.5 ± 13.6 vs 73.5 ± 5.5 mmHg; P = 0.0146), waist circumference (76.0 ± 11.8 vs 65.9 ± 9.7; P = 0.0087) and subcutaneous adipose tissue (135.6 ± 88.6 vs 69.3 ± 59.9; P = 0.01) than controls. Visceral adipose tissue, intramyocellular lipid levels and adiponectin were not different between groups. TS girls also had higher triglycerides (1.1 ± 0.6 vs 0.7 ± 0.3; P = 0.003), total cholesterol (4.4 ± 0.7 vs 3.9 ± 0.4; P = 0.02) and hsCRP (2.0 ± 1.9 vs 0.8 ± 0.3; P = 0.01). CONCLUSIONS: TS girls exhibit more cardiometabolic risk factors and reduced beta cell function compared with age- and BMI-SDS-matched girls. Increased awareness of early risk of type 2 diabetes mellitus and hypertension in TS girls is needed.

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

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.