Noel McCaffrey

Exercise intensity‐dependent regulation of peroxisome proliferator‐activated receptor γ coactivator‐1α mRNA abundance is associated with differential activation of upstream signalling kinases in human skeletal muscle

Skeletal muscle contraction increases intracellular ATP turnover, calcium flux, and mechanical stress, initiating signal transduction pathways that modulate peroxisome proliferator‐activated receptor γ coactivator‐1α (PGC‐1α)‐dependent transcriptional programmes. The purpose of this study was to determine if the intensity of exercise regulates PGC‐1α expression in human skeletal muscle, coincident with activation of signalling cascades known to regulate PGC‐1α transcription. Eight sedentary males expended 400 kcal (1674 kj) during a single bout of cycle ergometer exercise on two separate occasions at either 40% (LO) or 80% (HI) of . Skeletal muscle biopsies from the m. vastus lateralis were taken at rest and at +0, +3 and +19 h after exercise. Energy expenditure during exercise was similar between trials, but the high intensity bout was shorter in duration (LO, 69.9 ± 4.0 min; HI, 36.0 ± 2.2 min, P < 0.05) and had a higher rate of glycogen utilization (P < 0.05). PGC‐1α mRNA abundance increased in an intensity‐dependent manner +3 h after exercise (LO, 3.8‐fold; HI, 10.2‐fold, P < 0.05). AMP‐activated protein kinase (AMPK) (2.8‐fold, P < 0.05) and calcium/calmodulin‐dependent protein kinase II (CaMKII) phosphorylation (84%, P < 0.05) increased immediately after HI but not LO. p38 mitogen‐activated protein kinase (MAPK) phosphorylation increased after both trials (∼2.0‐fold, P < 0.05), but phosphorylation of the downstream transcription factor, activating transcription factor‐2 (ATF‐2), increased only after HI (2.4‐fold, P < 0.05). Cyclic‐AMP response element binding protein (CREB) phosphorylation was elevated at +3 h after both trials (∼80%, P < 0.05) and class IIa histone deacetylase (HDAC) phosphorylation increased only after HI (2.0‐fold, P < 0.05). In conclusion, exercise intensity regulates PGC‐1α mRNA abundance in human skeletal muscle in response to a single bout of exercise. This effect is mediated by differential activation of multiple signalling pathways, with ATF‐2 and HDAC phosphorylation proposed as key intensity‐dependent mediators.

ImPact Test-Retest Reliability: Reliably Unreliable?

CONTEXT Computerized neuropsychological testing is commonly used in the assessment and management of sport-related concussion. Even though computerized testing is widespread, psychometric evidence for test-retest reliability is somewhat limited. Additional evidence for test-retest reliability is needed to optimize clinical decision making after concussion. OBJECTIVE To document test-retest reliability for a commercially available computerized neuropsychological test battery (ImPACT) using 2 different clinically relevant time intervals. DESIGN Cross-sectional study. SETTING Two research laboratories. PATIENTS OR OTHER PARTICIPANTS Group 1 (n = 46) consisted of 25 men and 21 women (age = 22.4 ± 1.89 years). Group 2 (n = 45) consisted of 17 men and 28 women (age = 20.9 ± 1.72 years). INTERVENTION(S) Both groups completed ImPACT forms 1, 2, and 3, which were delivered sequentially either at 1-week intervals (group 1) or at baseline, day 45, and day 50 (group 2). Group 2 also completed the Green Word Memory Test (WMT) as a measure of effort. MAIN OUTCOME MEASURES Intraclass correlation coefficients (ICCs) were calculated for the composite scores of ImPACT between time points. Repeated-measures analysis of variance was used to evaluate changes in ImPACT and WMT results over time. RESULTS The ICC values for group 1 ranged from 0.26 to 0.88 for the 4 ImPACT composite scores. The ICC values for group 2 ranged from 0.37 to 0.76. In group 1, ImPACT classified 37.0% and 46.0% of healthy participants as impaired at time points 2 and 3, respectively. In group 2, ImPACT classified 22.2% and 28.9% of healthy participants as impaired at time points 2 and 3, respectively. CONCLUSIONS We found variable test-retest reliability for ImPACT metrics. Visual motor speed and reaction time demonstrated greater reliability than verbal and visual memory. Our current data support a multifaceted approach to concussion assessment using clinical examinations, symptom reports, cognitive testing, and balance assessment.

Influence of acute exercise with and without carbohydrate replacement on postprandial lipid metabolism

Acute exercise, undertaken on the day before an oral fat tolerance test (OFTT), typically reduces postprandial triglycerides (TG) and increases high-density lipoprotein-cholesterol (HDL-C). However, the benefits of acute exercise may be overstated when studies do not account for compensatory changes in dietary intake. The objective of this study was to determine the influence of acute exercise, with and without carbohydrate (CHO) replacement, on postprandial lipid metabolism. Eight recreationally active young men underwent an OFTT on the morning after three experimental conditions: no exercise [control (Con)], prolonged exercise without CHO replacement (Ex-Def) and prolonged exercise with CHO replacement to restore CHO and energy balance (Ex-Bal). The exercise session in Ex-Def and Ex-Bal consisted of 90 min cycle ergometry at 70% peak oxygen uptake (Vo(2peak)) followed by 10 maximal 1-min sprints. CHO replacement was achieved using glucose solutions consumed at 0, 2, and 4 h postexercise. Muscle glycogen was 40 +/- 4% (P < 0.05) and 94 +/- 3% (P = 0.24) of Con values on the morning of the Ex-Def and Ex-Bal OFTT, respectively. Postprandial TG were 40 +/- 14% lower and postprandial HDL-C, free fatty acids, and 3-hydroxybutyrate were higher in Ex-Def compared with Con (P < 0.05). Most importantly, these exercise effects were not evident in Ex-Bal. Postprandial insulin and glucose and the homeostatic model assessment of insulin resistance (HOMA(IR)) were not significantly different across trials. There was no relation between the changes in postprandial TG and muscle glycogen across trials. In conclusion, the influence of acute exhaustive exercise on postprandial lipid metabolism is largely dependent on the associated CHO and energy deficit.

Similar to adiponectin, serum levels of osteoprotegerin are associated with obesity in healthy subjects

An increase in serum osteoprotegerin (OPG) is associated with type 2 diabetes mellitus, the severity of vascular calcification, and coronary artery disease. Obesity is a risk factor for diabetes and cardiovascular disease, but little is known about the relationship between OPG and obesity. The purpose of this study was to determine if changes in body mass index (BMI) and insulin sensitivity influence circulating OPG in healthy subjects. A total of 100 subjects (36 lean, 41 overweight, and 23 obese) with normal glucose tolerance, blood pressure, and electrocardiogram stress test result volunteered for this study. Insulin sensitivity was estimated using a 2-hour oral glucose tolerance test with oral glucose insulin sensitivity analysis. Osteoprotegerin, tumor necrosis factor-related apoptosis-inducing ligand (TRAIL),soluble receptor activator of nuclear factor-κβ ligand (sRANKL), and adiponectin were analyzed using commercially available enzyme-linked immunosorbent assays. Osteoprotegerin (P < .01) and adiponectin (P < .001) were significantly decreased in the obese compared with lean subjects. There was no significant difference between BMI categories for TRAIL or sRANKL. Controlling for age and sex, there was a significant correlation between OPG and adiponectin (r = 0.391, P < .001), BMI (r = -0.331, P < .001), waist circumference (r = -0.268, P < .01), homeostasis model assessment of insulin resistance (r = -0.222, P < .05), and oral glucose insulin sensitivity (r = 0.221, P < .05). Both OPG and adiponectin were negatively correlated with body weight, BMI, waist circumference, and fasting plasma insulin while being positively correlated with insulin sensitivity (P < .05). Controlling for age, sex, and BMI, TRAIL was positively related to fat mass (r = 0.373, P < .001) and waist circumference (r = 0.257, P < .05). In contrast to patients with type 2 diabetes mellitus, circulating OPG is lower in obese, but otherwise healthy subjects and is positively correlated with indices of insulin sensitivity.

Lipoprotein particle distribution and skeletal muscle lipoprotein lipase activity after acute exercise

BackgroundMany of the metabolic effects of exercise are due to the most recent exercise session. With recent advances in nuclear magnetic resonance spectroscopy (NMRS), it is possible to gain insight about which lipoprotein particles are responsible for mediating exercise effects.MethodsUsing a randomized cross-over design, very low density lipoprotein (VLDL) responses were evaluated in eight men on the morning after i) an inactive control trial (CON), ii) exercising vigorously on the prior evening for 100 min followed by fasting overnight to maintain an energy and carbohydrate deficit (EX-DEF), and iii) after the same exercise session followed by carbohydrate intake to restore muscle glycogen and carbohydrate balance (EX-BAL).ResultsThe intermediate, low and high density lipoprotein particle concentrations did not differ between trials. Fasting triglyceride (TG) determined biochemically, and mean VLDL size were lower in EX-DEF but not in EX-BAL compared to CON, primarily due to a reduction in VLDL-TG in the 70–120 nm (large) particle range. In contrast, VLDL-TG was lower in both EX-DEF and EX-BAL compared to CON in the 43–55 nm (medium) particle range. VLDL-TG in smaller particles (29–43 nm) was unaffected by exercise. Because the majority of VLDL particles were in this smallest size range and resistant to change, total VLDL particle concentration was not different between any of these conditions. Skeletal muscle lipoprotein lipase (LPL) activity was also not different across these 3 trials. However, in CON only, the inter-individual differences in LPL activity were inversely correlated with fasting TG, VLDL-TG, total, large and small VLDL particle concentration and VLDL size, indicating a regulatory role for LPL in the non-exercised state.ConclusionsThese findings reveal a high level of differential regulation between different sized triglyceride-rich lipoproteins following exercise and feeding, in the absence of changes in LPL activity.

PATHway I: design and rationale for the investigation of the feasibility, clinical effectiveness and cost-effectiveness of a technology-enabled cardiac rehabilitation platform

Introduction Exercise-based cardiac rehabilitation (CR) independently alters the clinical course of cardiovascular diseases resulting in a significant reduction in all-cause and cardiac mortality. However, only 15%–30% of all eligible patients participate in a phase 2 ambulatory programme. The uptake rate of community-based programmes following phase 2 CR and adherence to long-term exercise is extremely poor. Newer care models, involving telerehabilitation programmes that are delivered remotely, show considerable promise for increasing adherence. In this view, the PATHway (Physical Activity Towards Health) platform was developed and now needs to be evaluated in terms of its feasibility and clinical efficacy. Methods and analysis In a multicentre randomised controlled pilot trial, 120 participants (m/f, age 40–80 years) completing a phase 2 ambulatory CR programme will be randomised on a 1:1 basis to PATHway or usual care. PATHway involves a comprehensive, internet-enabled, sensor-based home CR platform and provides individualised heart rate monitored exercise programmes (exerclasses and exergames) as the basis on which to provide a personalised lifestyle intervention programme. The control group will receive usual care. Study outcomes will be assessed at baseline, 3 months and 6 months after completion of phase 2 of the CR programme. The primary outcome is the change in active energy expenditure. Secondary outcomes include cardiopulmonary endurance capacity, muscle strength, body composition, cardiovascular risk factors, peripheral endothelial vascular function, patient satisfaction, health-related quality of life (HRQoL), well-being, mediators of behaviour change and safety. HRQoL and healthcare costs will be taken into account in cost-effectiveness evaluation. Ethics and dissemination The study will be conducted in accordance with the Declaration of Helsinki. This protocol has been approved by the director and clinical director of the PATHway study and by the ethical committee of each participating site. Results will be disseminated via peer-reviewed scientific journals and presentations at congresses and events. Trial registration number NCT02717806. This trial is currently in the pre-results stage.

Epidemiology of injury in male adolescent Gaelic games

OBJECTIVES There is a lack of epidemiological research in adolescent Gaelic games, with previous research primarily focusing on elite adult males. This study aimed to prospectively capture the epidemiology of injury in male adolescent Gaelic games over one year. DESIGN Prospective cohort study. METHODS Two hundred and ninety two (15.7±0.8 years) male adolescent Gaelic footballers and hurlers took part in a one year prospective epidemiological study. Injuries were assessed weekly by a certified Athletic Rehabilitation Therapist and an injury was defined as any injury sustained during training or competition resulting in restricted performance or time lost from play. An injury report form was utilised to standardise injury information. RESULTS Match injuries were more frequent in Gaelic footballers (9.26 per 1000h) and hurlers (11.11 per 1000h) than training injuries (2.69 and 3.01 per 1000h, respectively). Over a quarter of injuries in adolescent Gaelic footballers (26.7%) and hurlers (26.5%) were overuse in nature. Recurrent injuries were also frequent, particularly in adolescent Gaelic footballers (47.3%). Lower limb injuries predominated (football 74.7%, hurling 58%), particularly in the knee (18.7%, 20.0%) and ankle (12.0%, 10.0%). Hamstring injuries were more frequent in footballers (13.3%), with lower back injuries more common in hurlers (22.0%). Minor injuries were common in hurling (61.7%), with moderate (20.8%) and severe (37.5%) injuries predominant in Gaelic football. CONCLUSIONS Injuries are frequent in adolescent Gaelic games and this study sets the scene for the establishment of injury prevention strategies for this at risk population.

Physiological and health characteristics of ex-jockeys.

OBJECTIVES The long-term health implications resulting from extreme and chronic weight cycling and the associated energy restricted lifestyle of a professional jockey remain unknown. The aim of the present study was to describe and evaluate the physiological and health characteristics of retired jockeys. DESIGN Cross-sectional. METHODS Retired male jockeys (n=28; age 59±6yr; height 1.65±0.03m; body mass 73.7±10.9kg; BMI 26.9±3.8kgm(-2)) participated. Body composition (by dual energy X-ray absorptiometry; DXA), resting metabolic rate (RMR), glucose metabolism (by oral glucose tolerance test; OGTT), lipids and thyroid function were assessed. All data were interpreted in relation to established age specific reference ranges for the particular assessment undertaken. RESULTS Forty three percent of the retired jockeys were classified as overweight, while 21% were obese. RMR was calculated as 1447±201kcalday(-1). Mean total cholesterol was 5.93±1.5mmolL(-1) for those not on cholesterol lowering medication and 5.09±1.1mmolL(-1) for those currently taking medication. No abnormalities in glucose metabolism and thyroid function were found. CONCLUSIONS Chronic weight cycling during a career as a professional jockey did not induce any health consequences in the retired jockeys assessed in this study, however enhanced weight gain and dyslipidaemia were evident. Results suggest jockeys should be tracked longitudinally throughout their racing career and beyond to further establish long-term physical health implications associated with the current lifestyle of a professional jockey.

Epidemiology of injury in male collegiate Gaelic footballers in one season.

Despite the popularity of collegiate Gaelic football in Ireland and the recent expansion into the United Kingdom and United States, no previous study has examined injury incidence. A prospective epidemiological study was implemented to establish injury incidence in 217 (19.3 ± 1.9 years) male collegiate Gaelic footballers from two collegiate institutions in one season. An injury was defined as any injury sustained during training or competition resulting in time lost from play or athlete reported restricted performance. Athletic therapy and training students, alongside a certified athletic and rehabilitation therapist, attended all training/matches over one season, and injuries were recorded using a standardized injury report form. The match injury rate was 25.1 injuries per 1000 h, with a significantly higher match injury rate noted in fresher players (players in their 1st year of higher education) (41.6 injuries per 1000 h) than senior players (12.7 injuries per 1000 h). Lower limb injuries were predominant (71.1%), particularly in the hamstring (15.5%), knee (14.1%), and ankle (11.3%). Soft‐tissue injuries predominated, particularly strains (32.4%) and sprains (27.5%). A scan and surgery was required in 31% and 12% of injuries, respectively. Thus, injuries are prevalent in male collegiate Gaelic football, and injury prevention programs are required.

The novel use of a SenseCam and accelerometer to validate training load and training information in a self-recall training diary

Abstract Self-recall training diaries are a frequently used tool to quantify training load and training information. While accelerometers are predominantly used to validate training diaries, they are unable to validate contextual training information. Thus this study aimed to examine the novel use of data fusion from a wearable camera device (SenseCam) and accelerometer to validate a self-recall training diary. Thirty participants filled in a training diary for 1 day while simultaneously wearing a SenseCam and accelerometer. The training diary was validated using Bland–Altman plots, Spearman’s rank-order correlation, percentage agreement and κ measure of agreement between the diary and the SenseCam and accelerometer. The results demonstrated overall agreement, and no bias, between the training diary and the accelerometer for training intensity, and the SenseCam for duration of activity and travel time. A positive correlation was found for duration (r = 0.82, P < 0.001) and intensity (r = 0.67, P < 0.001). Hundred per cent agreement was found between the SenseCam and training diary for activity, training surface and footwear (κ = 1, P < 0.0001), with a lower agreement noted for sports played (97.3%, κ = 0.91, P < 0.0001). The self-recall training diary was found to be a valid measure of capturing training load and training information using the combined wearable camera device and accelerometer.