Costas Tsakirides

OBJECTIVE: To determine whether lipid profiles and recurrent coronary heart disease (CHD) risk could be modified in patients with and without diabetes mellitus undergoing long-term cardiac rehabilitation (CR). DESIGN: Retrospective analysis of patient case records. SETTING: Community-based phase 4 CR program. PARTICIPANTS: Patients without diabetes (n=154; 89% men; mean ± SD age, 59.6 ± 8.5y; body mass index [BMI], 27.0 ± 3.5 kg/m²) and patients with diabetes (n=20; 81% men; mean age, 63.0 ± 8.7y; BMI, 28.7 ± 3.3 kg/m²) who completed 15 months of CR. INTERVENTIONS: Exercise testing and training, risk profiling, and risk-factor education. MAIN OUTCOME MEASURES: Cardiometabolic risk factors and 2- to 4-year Framingham recurrent CHD risk scores were assessed. RESULTS: At follow up, a significant main effect for time was evident for decreased body mass and waist circumference and improved low-density lipoprotein cholesterol (LDL-C) level and submaximal cardiorespiratory fitness (all P<.05), showing the benefits of CR in both groups. However, a significant group-by-time interaction effect was evident for high-density lipoprotein cholesterol (HDL-C) level and total cholesterol (TC)/HDL-C ratio (both P<.05). TC/HDL-C ratio improved (5.0 ± 1.5 to 4.4 ± 1.3) in patients without diabetes, but showed no improvement in patients with diabetes (4.8 ± 1.6 v 4.9 ± 1.6). CONCLUSIONS: We showed that numerous anthropometric, submaximal fitness, and cardiometabolic risk variables (especially LDL-C level) improved significantly after long-term CR. However, some aspects of cardiometabolic risk (measures incorporating TC and HDL-C) improved significantly in only the nondiabetic group.

Aim: To conduct a preliminary study to evaluate gender differences in psychological health status and physical activity (PA) levels in male and female patients following completion of 6 weeks of phase III cardiac rehabilitation (CR). Methods: Cardiac patients who had completed structured hospital-based CR were invited to participate in the study. Patients completed three questionnaires which evaluated current and past PA levels, physical self-efficacy, and anxiety and depression. Results: Sixteen male participants (mean age 55±8 years), and six females (mean age 55±7 years) were recruited. Males were significantly more active (12±9 hours of total PA per week) than females (8±4 hours of PA per week; P=0.018). Females with social support during exercise engaged in more weekly PA than those who exercise alone (P<0.05). Conversely, males performed more PA alone (14±9 hours) than with others (11±9 hours; P<0.05). Patients (males and females) who exercised in groups had higher physical self-efficacy than those that engaged in exercise alone (P<0.05). The HADS scores revealed that overall males and females were not anxious or depressed (depression sub-score: 3.0±2.4 versus 1.7±2.8; P=0.33; anxiety sub-score: 5.7±2.3 vs 4.3±3.5; P=0.37). A significant gender by exercise environment (exercise alone or undertaken some group exercise) interaction was evident (P=0.045) for depression, but not for anxiety (P=0.122). Conclusion: These preliminary results indicate that gender differences in psychological well-being and physical activity status may exist following standardized short-term phase III cardiac rehabilitation. We recommend that CR services should consider the differing needs of both males and females.

Aim: to compare patient and staff perceptions of phase III cardiac rehabilitation delivered in a hospital versus community setting. Method: data were collected by semi-structured interviews with staff and patients. Patients and staff members were interviewed in one of two local leisure centres and in the cardiac unit at Leeds General Infirmary. Five patients who had previously attended a hospital-based phase III programme, four patients who attended a communitybased programme, and four hospital and community staff members participated. Data were analysed using a content analysis technique based on the ‘framework’ approach. Results: three patients admitted having negative expectations of the community-based phase III programme. Maintaining attendance is more challenging in the community; however, progression rates to phase IV were better. Differences between programmes were identified in adherence to sessions, type and number of staff present, and number of sessions provided each week. All patients found the sessions helped with their rehabilitation and all stated that they would recommend their programme to others. Conclusion: both community- and hospital-based rehabilitation programmes were seen as successful by both patients and staff. The emergence of the community programme has proven to be a valuable additional service for cardiac patients. However, if the future of phase III cardiac rehabilitation in Leeds is to be community-based, then specific issues such as exercise adherence will need to be addressed.

The purpose of this study was to evaluate the effects of an 8-week, low frequency, hospital-based resistance training programme on metabolic risk factors in type 2 diabetic patients. Participants were self-selected into either an 8-week resistance training programme or a control group. Anthropometric indices, fasting glucose, HbA1c, total cholesterol, HDL and LDL lipoproteins, triglycerides, fasting insulin, and insulin sensitivity were assessed at baseline and 8 weeks later. Six participants were recruited (age 53 ± 9 years; BMI 32 ± 3 kg·m

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The efficacy of exercise-based cardiac rehabilitation (CR) to improve aerobic fitness and reduce mortality has been questioned, partly due to the insufficient exercise dose (namely frequency of exercise sessions). Lack of frequency of exercise sessions is mainly attributed to staffing and funding limitations, particularly in the UK. Despite a lack of prescribed exercise sessions, it is imperative patients adhere to the prescribed intensity and duration targets. To offset the inadequate time available to instruct CR patients, pre-CR instructional digital videos could inform patients about the prescribed exercise dose (intensity and duration). This may enhance their understanding of exercise targets when commencing CR. PURPOSE: The study evaluated the effectiveness of instructional videos in improving patient recall of targeted rating of perceived exertion (RPE) and exercise duration in a CR setting. METHODS: Fifty-five patients in North Wales, UK, were recruited. They were provided a digital video via a weblink to watch before attending CR, explaining the specific exercise duration and intensity targets. After four exercise classes, patients completed a survey about the video’s usefulness in explaining correct exercise methods, their confidence in meeting intensity and duration targets, and their recall of RPE and duration targets. Quantitative data is presented as frequency and percentage of responses. RESULTS: Of the twenty-three patients completing the survey, 47.8% (n=11) found the video extremely useful, and 34.8% (n=8) found it very useful. Overall, 21.7% (n=5) were extremely confident and 43.5% (n=10) were very confident that they were meeting the prescribed exercise targets. However, 34.8% (n=8) failed to recall the correct RPE targets for circuit-based CR exercise and 43.5% (n=10) failed to recall the correct RPE targets for gym-based CR exercise. Additionally, 60.9% (n=14) were unable to accurately recall the prescribed exercise duration targets. CONCLUSION: Despite most patients feeling confident about their understanding of exercise targets, the actual recall of RPE and exercise duration targets was limited, indicating a gap between perceived knowledge and recall. This highlights the need for more effective instructional interventions in CR programmes.

The efficacy of exercise-based cardiac rehabilitation (CR) to improve aerobic fitness and reduce mortality has been questioned, partly due to the insufficient exercise dose (namely frequency of exercise sessions). Lack of frequency of exercise sessions is mainly attributed to staffing and funding limitations, particularly in the UK. Despite a lack of prescribed exercise sessions, it is imperative patients adhere to the prescribed intensity and duration targets. To offset the inadequate time available to instruct CR patients, pre-CR instructional digital videos could inform patients about the prescribed exercise dose (intensity and duration). This may enhance their understanding of exercise targets when commencing CR. PURPOSE: The study evaluated the effectiveness of instructional videos in improving patient recall of targeted rating of perceived exertion (RPE) and exercise duration in a CR setting. METHODS: Fifty-five patients in North Wales, UK, were recruited. They were provided a digital video via a weblink to watch before attending CR, explaining the specific exercise duration and intensity targets. After four exercise classes, patients completed a survey about the video’s usefulness in explaining correct exercise methods, their confidence in meeting intensity and duration targets, and their recall of RPE and duration targets. Quantitative data is presented as frequency and percentage of responses. RESULTS: Of the twenty-three patients completing the survey, 47.8% (n = 11) found the video extremely useful, and 34.8% (n = 8) found it very useful. Overall, 21.7% (n = 5) were extremely confident and 43.5% (n = 10) were very confident that they were meeting the prescribed exercise targets. However, 34.8% (n = 8) failed to recall the correct RPE targets for circuit-based CR exercise and 43.5% (n = 10) failed to recall the correct RPE targets for gym-based CR exercise. Additionally, 60.9% (n = 14) were unable to accurately recall the prescribed exercise duration targets. CONCLUSIONS: Despite most patients feeling confident about their understanding of exercise targets, the actual recall of RPE and exercise duration targets was limited, indicating a gap between perceived knowledge and recall. This highlights the need for more effective instructional interventions in CR programmes.

Objectives This study aimed to characterise the exercise performed in UK cardiac rehabilitation (CR) and explore relationships between exercise dose and changes in physiological variables. Design Observational cohort study. Setting Outpatient community-based CR in Leeds, UK. Rehabilitation sessions were provided twice per week for 6 weeks. Participants Sixty patients (45 male/15 female 33–86 years) were recruited following referral to local outpatient CR. Outcome measures The primary outcome was heart rate achieved during exercise sessions. Secondary outcomes were measured before and after CR and included incremental shuttle walk test (ISWT) distance and speed, blood pressure, brachial artery flow-mediated dilatation, carotid arterial stiffness and accelerometer-derived habitual physical activity behaviours. Results The mean % of heart rate reserve patients exercised at was low and variable at the start of CR (42%±16 %) and did not progress by the middle (48%±17 %) or end (48%±16 %) of the programme. ISWT performance increased following CR (440±150 m vs 633±217 m, p<0.001); however, blood pressure, body weight, endothelial function, arterial stiffness and habitual physical activity behaviours were unchanged following 6 weeks of CR (p>0.05). Conclusion Patients in a UK CR cohort exercise at intensities that are variable but generally low. The exercise dose achieved using this CR format appears inadequate to impact markers of health. Attending CR had no effect on physical activity behaviours. Strategies to increase the dose of exercise patients achieve during CR and influence habitual physical activity behaviours may enhance the effectiveness of UK CR.

Cardiac Rehabilitation (CR) is a multifaceted secondary prevention programme where nutritional education is a central component. Given the high prevalence rates of protein and energy malnutrition in clinical populations including CR patients, it is of upmost importance that current dietary interventions positively modify dietary behaviour. In the UK, the so-called “Mediterranean diet,” is distinguished by a somewhat high proportion of fruit, cereals, and vegetables and consumption of fish and poultry as the main sources of protein. Specifically, research based recommendations suggest protein intakes of up to 1.5g·kg-1 of body mass (BM) for diseased elderly populations as a means to promote recovery and good health. Therefore, this study aimed a) to investigate patients’ dietary intakes with emphasis on protein and energy intakes and b) the effectiveness of a 30-min nutritional education session provided as part of the UK standard CR provision. Following NHS ethics approval, 23 male CR patients aged (64 (± 12) years) enrolled and completed a six-week CR programme. Patients with valve replacement and heart failure were excluded from the study. Patients received a nutritional education session at the start and completed a three-day diet diary in week one and six of the CR programme. Estimated energy requirements were calculated by the updated Oxford equations (Henry, 2005) and a physical activity (PA) factor based on patients’ PA levels. Average energy intakes (EI) at week one (1871.3±583.7 kcal) and six (1674.7±500.2 kcal) were below recommendations (2098.7±329.6 kcal and 2391.4±313.1 kcal respectively) but this was only significant at week six (p=0.000). Furthermore, EI at week six was reduced compared to baseline (-7±25.3%, p=0.02). On average, for the duration of the programme, patients were consuming 0.90±0.3, 2.5±0.9, 0.7±0.3 g·kg-1·BM·d-1 protein, CHO, and fat respectively. Our data confirms that protein and energy intakes were significantly below recommendations for individuals recovering from disease. It appears that one 30-min nutritional education session received as part of the CR provision is not sufficient enough to cause positive dietary changes. Therefore, there is a real need to address the dietary deficiencies of CR patients through additional investments in nutritional education.

AIMS: To investigate the relationship between exercise participation, exercise 'dose' expressed as metabolic equivalent (MET) hours (h) per week, and prognosis in individuals attending an extended, community-based exercise rehabilitation programme. METHODS: Cohort study of 435 participants undertaking exercise-based cardiac rehabilitation (CR) in Leeds, West Yorkshire, UK between 1994 and 2006, followed up to 1 November 2013. MET intensity of supervised exercise was estimated utilising serial submaximal exercise test results and corresponding exercise prescriptions. Programme participation was routinely monitored. Cox regression analysis including time-varying and propensity score adjustment was applied to identify predictors of long-term, all-cause mortality across exercise dose and programme duration groups. RESULTS: There were 133 events (31%) during a median follow-up of 14 years (range, 1.2 to 18.9 years). The significant univariate association between exercise dose and all-cause mortality was attenuated following multivariable adjustment for other predictors, including duration in the programme. Longer-term adherence to supervised exercise training (>36 months) was associated with a 33% lower mortality risk (multivariate-adjusted HR: 0.67; 95% CI: 0.47 to 0.97; p=0.033) compared with all lesser durations of CR (3, 12, 36 months), even after adjustment for baseline fitness, comorbidities and survivor bias. CONCLUSION: Exercise dose (MET-h per week) appears less important than long-term adherence to supervised exercise for the reduction of long-term mortality risk. Extended, supervised CR programmes within the community may play a key role in promoting long-term exercise maintenance and other secondary prevention therapies for survival benefit.

To examine the association between submaximal cardiorespiratory fitness (sCRF) and all-cause mortality in a cardiac rehabilitation (CR) cohort.Retrospective cohort study of participants entering CR between 26 May 1993 and 16 October 2006, followed up to 1 November 2013 (median 14 years, range 1.2-19.4 years).A community-based CR exercise programme in Leeds, West Yorkshire, UK.A cohort of 534 men (76%) and 136 women with a clinical diagnosis of coronary heart disease (CHD), aged 22-82 years, attending CR were evaluated for the association between baseline sCRF and all-cause mortality. 416 participants with an exercise test following CR (median 14 weeks) were examined for changes in sCRF and all-cause mortality.All-cause mortality and change in sCRF expressed in estimated metabolic equivalents (METs).Baseline sCRF was a strong predictor of all-cause mortality; compared to the lowest sCRF group (<5 METs for women and <6 METs for men), mortality risk was 41% lower in those with moderate sCRF (HR 0.59; 95% CI 0.42 to 0.83) and 60% lower (HR 0.40; 95% CI 0.25 to 0.64) in those with higher sCRF levels (≥7 METs women and ≥8 METs for men). Although improvement in sCRF at 14 weeks was not associated with a significant mortality risk reduction (HR 0.91; 95% CI 0.79 to 1.06) for the whole cohort, in those with the lowest sCRF (and highest all-cause mortality) at baseline, each 1-MET improvement was associated with a 27% age-adjusted reduction in mortality risk (HR 0.73; 95% CI 0.57 to 0.94).Higher baseline sCRF is associated with a reduced risk of all-cause mortality over 14 years in adults with CHD. Improving fitness through exercise-based CR is associated with significant risk reduction for the least fit.

AIM Circulating endothelial progenitor cells (EPCs) are known to play an important role in vascular healing and neovascularization. Exercise is an effective means to mobilise EPCs into the circulation. However, since different modes of exercise are associated with different physiological responses, the mobilisation of EPCs could vary in response to the exercise mode undertaken. Therefore, the purpose of this study was to examine the acute effects of different exercise modalities on EPCs. MATERIAL & METHOD Ten young active healthy adults (24.6 ± 2.1 years) completed three different experimental conditions: a) high intensity interval exercise (HIIE, 4 sets x 4 min at 85-95% HRmax with 3 min recovery at 50-55% HRmax), b) moderate-intensity continuous exercise (MICON, 70-80% HRmax), and c) wholebody resistance exercise (RE), consisting of seated leg press, chest press, leg extension, lateral pull down, upright row, and shoulder press (3 sets of 10 repetitions at 70% of 1RM with 1,5 min of recovery between sets and 3 min between exercises). A venous blood sample was taken pre-exercise, at 10 min post-exercise and at 2 h post-exercise. All laboratory visits took place a week apart, in a randomised cross-over fashion. Circulating EPCs were quantified by flow cytometry and were defined as CD34+/VEGFR2+/CD45dim. After testing for normality of distribution, a Friedman test was used to determinethe differences in percentage change (%) in circulating EPCs between the exercise conditions. Cohen’s d effect sizes were calculated and reported, as appropriate. RESULTS When examining the comparison of % change from pre-exercise to 10 min post-exercise between exercise conditions, there was a moderate difference between HIIE and RE (42.4 ± 17.7% vs 13.1 ± 18.6%, d = 0.51), a small difference between HIIE and MICON (42.4 ± 17.7% vs 20.1 ± 21.2%, d = 0.36), and a trivial difference between MICON and RE (20.1 ± 21.2% vs 13.1 ± 18.6%, d = 0.11). None of these differences was significant (p > 0.05). Comparison of the % changes from pre-exercise to 2 h post-exercise showed a significant difference between the three exercise conditions (p = 0.045). There was a large statistical difference between HIIE and RE (78.5 ± 28.1 % vs –2.0 ± 21.6 %, d = 1.01, p < 0.05), a moderate difference between MICON and RE (48.2 ± 27.5 % vs –2.0 ± 21.6 %, d = 0.64), and a small difference between HIIE and MICON (78.5 ± 28.1 % vs 48.2 ± 27.5, d = 0.35). CONCLUSIONS The level of EPC mobilisation depends on the exercise modality, with more pronounced effects found after HIIE and MICON, compared to RE.

Endothelial dysfunction, a key contributor to atherosclerosis, begins early in life and leads to vascular damage. Endothelial progenitor cells (EPCs), primarily derived from the bone marrow, play a crucial role in endothelial repair and vascular health, while reduced EPC levels are associated with cardiometabolic diseases and elevated cardiovascular risk. Exercise is known to improve endothelial health and influence EPC mobilisation. This thesis investigates the effects of various types of exercise on circulating EPCs, and angiogenic and inflammatory responses, through systematic review approaches and analytical methods. The first systematic review focuses on the acute and chronic effects of exercise in patients with cardiovascular and metabolic diseases, showing that EPC mobilisation is influenced by exercise intensity, particularly high-intensity interval exercise (HIIE) and moderate-intensity continuous exercise (MICON), and the clinical condition. Chronic trials revealed that MICON, alone or combined with resistance exercise (RE) or HIIE, enhances resting EPC levels. The second systematic review focuses on the prospective cohort studies in healthy adults. Acute trials found that prolonged exercise, RE, and maximal exercise significantly increased EPCs, while chronic trials demonstrated improvements in both EPC mobilisation and vascular function following HIIE and MICON. The experimental chapter presents a randomised cross-over pilot study in healthy young males, comparing the effects of HIIE, RE, and MICON on EPC mobilisation, angiogenic factors, and inflammatory markers. Although no significant condition-by-time-point interactions were observed (p = 0.249, η²p = 0.145), exploratory analysis revealed a statistically significant difference, with HIIE eliciting a greater acute response in EPC mobilisation compared to RE at the two-hour time point (78.5 ± 88.7% vs. -2.02 ± 68.4%, p = 0.017). Findings should be interpreted cautiously due to the small sample size and limited blood collection points. Strong associations were observed between exercise-induced EPC responses, endothelial function, and cardiometabolic health markers. The final chapter identifies limitations and proposes future research directions, emphasising the variability of EPC responses based on exercise type and individual health status. This thesis provides valuable insights into exercise as a mechanism to enhance EPC mobilisation and supports its role in cardiovascular health interventions. Future research involving diverse populations is needed to determine optimal exercise protocols for EPC enhancement.

Background: Acute hypoxia leads to a number of recognized changes in cardiopulmonary function, including acute increase in pulmonary artery systolic pressure. However, the comparative responses between men and women have been barely explored.Fourteen young healthy adult Caucasian subjects were studied at sea-level rest and then after >150-minute exposure to acute normobaric hypoxia (NH) equivalent to 4800 m and again at sea-level rest at 2 hours post-NH exposure. Cardiac function, using transthoracic echocardiography, physiological variables, and Lake Louise Scores for acute mountain sickness (AMS) were collected.All subjects completed the study, and there was an equal balance of men (n = 7) and women (n = 7) who were well matched for age (25.9 ± 3.2 vs. 27.3 ± 4.4; p = 0.51). NH exposure led to a significant increase in AMS scores and heart rate, as well as a fall in oxygen saturation, systolic blood pressure, and stroke volume. Stroke volumes and cardiac output were overall significantly higher in men than in women, and acute NH heart rate was higher in women (80.3 ± 10.2 vs. 69.7 ± 10.7/min; p < 0.05). NH led to a significant fall in the estimated left ventricular filling pressure (E/E'), an increase in the septal A' and S' and septal and lateral isovolumic contractile velocities (ICVs), and a fall in the E'A'S' ratio. The mitral E, lateral ICV, and E' velocities were all higher in men. Acute NH led to a significant increase in right ventricular systolic pressure and pulmonary vascular resistance. There was no interaction between NH exposure and sex for any parameters measured.Despite several baseline differences between men and women, the cardiopulmonary effects of acute NH are consistent between men and women.

Since the publication of the first systematic review in the late 1980s,1 the efficacy rationale for cardiac rehabilitation (CR) has evolved from a singular outcome of allcause mortality to additional multiple outcomes including cardiac mortality, quality of life, cardiorespiratory fitness (CRF), and cost savings in the form of preventing hospital readmissions.2 In the past decade, the case for the efficacy of reduced all-cause mortality has been challenged,3,4 but two questions arise around this matter: first, has some of the effective potency of exercise-based CR been lost due to modern cardiovascular health promotion and standards of medical, pharmacological, and surgical interventions being much improved5? Second, in research trials and in practice, has sufficient fidelity to an appropriate exercise dose been achieved, especially in those reports that have challenged the efficacy of CR4? In light of these questions, there has been a contemporary move to substantiate the efficacy of CR based on reduced hospital readmissions, health care costs, and quality of life.2 Given that a number of reviews, letters to editors, post hoc trials, and audit-data analyses have raised the question of exercise program dose fidelity,6,7 the aim of the current study was to investigate the influence of exercise fidelity on measures of CRF (incremental shuttle-walk test and heart rate walking speed index [HRWSI]) when patients were actively encouraged to achieve intensities >50% heart rate reserve (HRR).

Background: Adherence to cardiac rehabilitation (CR) programmes may be an important element for improving and maintaining physical activity (PA) behaviour in secondary prevention. Little is known about the PA behaviour in patients who have withdrawn from CR programmes. Therefore, a study was carried out to identify the reasons for withdrawal and the stage of PA readiness in those patients previously engaged in a Leeds-based community CR programme. Methods: A cross-sectional study was conducted using a telephone questionnaire to determine causes of withdrawal. A questionnaire based on the transtheoretical model of change was used to assess changes in PA readiness in these patients. Results: 101 withdrawn patients (mean age = 61 years; 72% male) were identified. It was found that 20 patients had relapsed beyond baseline (preparation phase) into pre-contemplation and contemplation phases and 15 reported they were in the preparation phase. However, the majority of patients remained in the action (18) and maintenance (48) phases of the transtheoretical model. Patients reported the following reasons for withdrawal: joined other facilities (16%); injury or illness (3%); family demands (7%); work demands (14%); lack of motivation (4%); lack of enjoyment (11%); lack of transport (10%); lack of time (10%); too expensive (6%); too crowded (4%). Conclusion: 66% of patients who had withdrawn from a phase IV CR programme remained in an advanced stage of PA readiness. Drop-out was due to a combination of financial, physical and lifestyle factors.

Circulating endothelial progenitor cells (EPCs) contribute to vascular healing and neovascularisation, while exercise is an effective means to mobilise EPCs into the circulation. Objectives: to systematically examine the acute and chronic effects of different forms of exercise on circulating EPCs in healthy populations. Methods: Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines were followed. Results: Thirty-one articles met the inclusion criteria including 747 participants aged 19 to 76 years. All included trials used flow cytometry for identification of circulating EPCs. Eight and five different EPC phenotypes were identified in the acute and chronic trials respectively. In the acute trials, moderate intensity continuous (MICON), maximal, prolonged endurance, resistance and high intensity interval training (HIIT) exercise protocols were utilised. Prolonged endurance and resistance exercise had the most profound effect on circulating EPCs followed by maximal exercise. In the chronic trials, MICON exercise, HIIT, HIIT compared to MICON and MICON compared to exergame (exercise modality based on an interactive video game) were identified. MICON exercise had a positive effect on circulating EPCs in older sedentary individuals which was accompanied by improvements in endothelial function and arterial stiffness. Long-stage HIIT (4min bouts) appears to be an effective means and superior than MICON exercise in mobilising circulating EPCs. In conclusion, both in acute and chronic trials the degree of exercise-induced EPC mobilisation depends upon the exercise regime applied. In future, more research is warranted to examine the dose-response relationship of different exercise forms on circulating EPCs using standardised methodology and EPC phenotype.

Background/aims: The primary aim of this study was to evaluate the effectiveness of two 30-minute dietary education sessions, within cardiac rehabilitation (CR), as a means to optimise nutrient and energy intakes (EI). A secondary aim was to evaluate patients’ habitual physical activity (PA) levels. Methods: Thirty patients (males: n = 24, 61.8 ± 11.2 years; females: n = 6, 66.7 ± 8.5 years) attended a six-week early outpatient CR programme in the UK and received two 30-minute dietary education sessions emphasising Mediterranean diet principles. EI and nutrient intakes were measured through completion of three-day food diaries in weeks one and six (before and after the dietary education sessions) to assess the impact of these sessions on nutrient intakes. At the same time-points, a sub-group (n = 13) of patients had their PA levels assessed via accelerometery to assess the impact of the CR programme on PA. Findings: Estimated energy requirements (EER) at week one (1988 ± 366 kcal . d -1 ) were not matched by actual EI (1785 ± 561 kcal . d -1 ) ( P = 0.047, d = -0.36). EI reduced to 1655 ± 470 kcal . d -1 at week six ( P = 0.66, d = -0.33) whereas EER increased as a function of increased activity (CR sessions). Nutrient intakes remained suboptimal, while no significant increases were observed in healthy fats and fibre, which consist core elements of a Mediterranean diet. Statistically significant increases were not observed in PA however patients decreased sedentary time by 11 ± 12% in week six compared to week one ( P = 0.009; d = -0.54). Conclusion : The present study findings suggest that two 30-minute dietary education sessions did not positively influence EI and nutrient intakes, while habitual PA levels were not significantly increased as a result of the CR programme. Future research should explore means of optimising nutrition and habitual PA within UK CR.

PURPOSE: Preparticipation health screening is recommended to detect individuals susceptible to serious adverse cardiovascular complications during exercise. Although expert opinion and best available scientific evidence have informed recent modifications, there remain limited experimental data to support or refute current practice. We therefore aimed to quantify the impact of change to the preparticipation health screening guidelines of the American College of Sports Medicine (ACSM) on risk classification and referral for medical clearance in a large cohort of undergraduate university students. METHODS: Participants attended the laboratory on a single occasion to undergo preparticipation health screening. Information concerning health status was obtained via self-report questionnaire and objective physiological assessment with all data recorded electronically and evaluated against the ACSM screening guidelines (9th and 10th editions). RESULTS: Five hundred and fifty-three students completed the study. The 9th edition screening guidance resulted in 82 subjects (15%) classified as high risk, almost one-quarter (24%) classified as moderate risk, and almost two-thirds (61%) classified as low risk. In comparison, the updated 10th edition screening guidance resulted in a significant reduction in those previously classified as either high risk (5%) or moderate risk (2%), respectively. The majority of subjects (93%) were therefore cleared to begin a structured exercise program. Taken together, approximately one-third (32%) fewer medical referrals were required when applying the updated 10th edition guidance (χ4 = 247.7, P < 0.001). CONCLUSIONS: The updated ACSM 10th edition preparticipation screening guidance reduces medical referrals by approximately one-third. These findings are in keeping with previous reports and thus serve to consolidate and justify recent modification-particularly when applied to young adult or adolescent populations. The findings and arguments presented should be used to refine and inform future guidance.

Background It is widely agreed that an increase in physical activity (PA) reduces mortality rates in cardiac rehabilitation (CR) patients. However, it is not known whether current standard CR training practices facilitate an increase in habitual PA. Therefore, the purpose of this study was to objectively measure PA levels in CR patients, both habitually and within structured CR sessions Design Observational study Methods Twenty patients were recruited during their CR pre assessment. Exclusion criteria included valve replacement and heart failure patients. Activity levels were assessed by waist-worn tri-axial accelerometry during the first and last week of a 6 week CR programme. Paired samples t-test and Wilcoxon signed rank tests were performed to identify changes in PA levels. Results Patients increased significantly light PA during the CR sessions compared to habitual PA levels outside CR (20 ± 11minutes versus 26 ± 8minutes, p=0.043). During week 6, patients also increased significantly the time spent in moderate and vigorous physical activity (MVPA) during the CR sessions when compared to week one (6.3 ± 6minutes versus 11 ± 7 minutes, p=<0.05) for moderate and vigorous intensities respectively. No changes were observed in PA levels outside the CR sessions. Conclusion Towards the end of the CR programme, a significant increase in the time spent in MVPA during formal CR sessions was not accompanied by an increase in habitual PA levels. Therefore, future CR programmes should place more emphasis on facilitating an increase in habitual PA.

Background: The conventional measurement of obesity utilises the body mass index (BMI) criterion. Although there are benefits to this method, there is concern that not all individuals at risk of obesity-associated medical conditions are being identified. Whole-body fat percentage (%FM), and specifically visceral adipose tissue (VAT) mass, are correlated with and potentially implicated in disease trajectories, but are not fully accounted for through BMI evaluation. The aims of this study were (a) to compare five anthropometric predictors of %FM and VAT mass, and (b) to explore new cut-points for the best of these predictors to improve the characterisation of obesity. Methods: BMI, waist circumference (WC), waist-to-hip ratio (WHR), waist-to-height ratio (WHtR) and waist/height0.5 (WHT.5R) were measured and calculated for 81 adults (40 women, 41 men; mean (SD) age: 38.4 (17.5) years; 94% Caucasian). Total body dual energy X-ray absorptiometry with Corescan (GE Lunar iDXA, Encore version 15.0) was also performed to quantify %FM and VAT mass. Linear regression analysis, stratified by sex, was applied to predict both %FM and VAT mass for each anthropometric variable. Within each sex, we used information theoretic methods (Akaike Information Criterion; AIC) to compare models. For the best anthropometric predictor, we derived tentative cut-points for classifying individuals as obese (>25% FM for men or >35% FM for women, or > highest tertile for VAT mass). Results: The best predictor of both %FM and VAT mass in men and women was WHtR. Derived cut-points for predicting whole body obesity were 0.53 in men and 0.54 in women. The cut-point for predicting visceral obesity was 0.59 in both sexes. Conclusions: In the absence of more objective measures of central obesity and adiposity, WHtR is a suitable proxy measure in both women and men. The proposed DXA-%FM and VAT mass cut-offs require validation in larger studies, but offer potential for improvement of obesity characterisation and the identification of individuals who would most benefit from therapeutic intervention. Key words: Fat mass; Visceral Fat; Measurement; DXA

Circulating endothelial progenitor cells (EPCs) contribute to vascular repair and their monitoring could have prognostic clinical value. Exercise is often prescribed for the management of cardiometabolic diseases, however, it is not fully understood how it regulates EPCs. Objectives: to systematically examine the acute and chronic effects of different exercise modalities on circulating EPCs in patients with cardiovascular and metabolic disease. Methods: Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines were followed. Results: Six electronic databases and reference lists of eligible studies were searched to April 2021. Thirty-six trials met the inclusion criteria including 1,731 participants. Acute trials: In chronic heart failure (CHF), EPC mobilisation was acutely increased after high intensity interval or moderate intensity continuous exercise training, while findings were inconclusive after a cardiopulmonary cycling exercise test. Maximal exercise tests acutely increased EPCs in ischaemic or revascularized coronary artery disease (CAD) patients. In peripheral arterial disease (PAD), EPC levels increased up to 24h post-exercise. In patients with compromised metabolic health, EPC mobilisation was blunted after a single exercise session. Chronic trials: In CHF and acute coronary syndrome, moderate intensity continuous protocols, with or without resistance exercise or calisthenics, increased EPCs irrespective of EPC identification phenotype. Findings were equivocal in CAD regardless of exercise mode, while in severe PAD disease EPCs increased. High intensity interval training increased EPCs in hypertensive metabolic syndrome and heart failure reduced ejection fraction. Conclusion: the clinical condition and exercise modality influence the degree of EPC mobilisation and magnitude of EPC increases in the long term.

There has been considerable debate as to whether different modalities of simulated hypoxia induce similar cardiac responses.This was a prospective observational study of 14 healthy subjects aged 22-35 years. Echocardiography was performed at rest and at 15 and 120 minutes following two hours exercise under normobaric normoxia (NN) and under similar PiO2 following genuine high altitude (GHA) at 3,375m, normobaric hypoxia (NH) and hypobaric hypoxia (HH) to simulate the equivalent hypoxic stimulus to GHA.All 14 subjects completed the experiment at GHA, 11 at NN, 12 under NH, and 6 under HH. The four groups were similar in age, sex and baseline demographics. At baseline rest right ventricular (RV) systolic pressure (RVSP, p = 0.0002), pulmonary vascular resistance (p = 0.0002) and acute mountain sickness (AMS) scores were higher and the SpO2 lower (p<0.0001) among all three hypoxic groups (GHA, NH and HH) compared with NN. At both 15 minutes and 120 minutes post exercise, AMS scores, Cardiac output, septal S', lateral S', tricuspid S' and A' velocities and RVSP were higher and SpO2 lower with all forms of hypoxia compared with NN. On post-test analysis, among the three hypoxia groups, SpO2 was lower at baseline and 15 minutes post exercise with GHA (89.3±3.4% and 89.3±2.2%) and HH (89.0±3.1 and (89.8±5.0) compared with NH (92.9±1.7 and 93.6±2.5%). The RV Myocardial Performance (Tei) Index and RVSP were significantly higher with HH than NH at 15 and 120 minutes post exercise respectively and tricuspid A' was higher with GHA compared with NH at 15 minutes post exercise.GHA, NH and HH produce similar cardiac adaptations over short duration rest despite lower SpO2 levels with GHA and HH compared with NH. Notable differences emerge following exercise in SpO2, RVSP and RV cardiac function.

It has previously been thought that reductions in inspired partial pressure of oxygen (PiO2) as a result of either reduced barometric pressure (PB) or inspired fraction of oxygen (FiO2) (normobaric hypoxia (NH)) would produce the same physiological responses. However, recent studies have reported differences between terrestrial altitude (TA) and NH. This may lead to differences in substrate utilisation during exercise; however, this is yet to be evaluated. The purpose was to compare whole-body substrate oxidation during s82 Day 2. Posters – Physiology and Nutrition Downloaded by exercise following co-ingestion of glucose and fructose on acute exposure to TA and NH. With institutional and Ministry of Defence ethical approval, eight male military personnel (age; 26.75 ± 4.86 years) completed a maximal oxygen uptake test and two experimental trials. These consisted of 2-hour cycling (~55%Wmax) at TA (3375 m; PiO2 ~ 96 mmHg) in the Italian Alps (Torino Hut) and in NH at an equivalent altitude (FiO2 ~ 13.8%, PiO2 ~ 96 mmHg). Carbohydrate (CHO) formulations (1.2 g · min-1 glucose and 0.6 g · min-1 fructose) were ingested immediately prior to and every 15 min throughout exercise. Whole-body substrate oxidation was measured using indirect calorimetry. Blood samples were drawn regularly for assessment of glucose, lactate, insulin and free fatty acids (FFA). Total energy expenditure was similar (P = 0.83; d = 0.03) in TA and NH (1285 ± 142 kcal and 1277 ± 98 kcal). Mean CHO oxidation during exercise was higher in NH (1.99 ± 0.25 g · min-1) compared to TA (1.20 ± 0.05 g · min-1), though not significant (P = 0.06; d = 0.91). The relative contribution ofCHO to the total energy yield was higher inNH compared to TA (69.82 ± 25.73% and 41.89 ± 22.57%), though not significant (P = 0.06; d = 0.50). Mean fat oxidation was higher at TA (0.72 ± 0.03 g · min-1) compared to NH (0.36 ± 0.07 g · min-1), though not significant (P = 0.06; d = 0.96). FFA concentrations were higher at TA compared to NH (P=0.003; d = 0.69), withTAproducing lower insulin concentrations than NH (P = 0.003; d = 0.46).There were no significant differences between the conditions for glucose (P = 0.06; d = 0.15) and lactate (P = 0.06; d = 0.19) concentrations. This study showed no significant difference in total energy expenditure at NH and TA. There was however evidence that the proportional part of CHO oxidation was increased during NH whilst the proportional part of fat oxidation was increased at TA. These differences just failed to reach statistical significance at the 5% level. Further investigation regarding substrate utilisation in reduced PB compared to FiO2 is warranted.

The hydration status of rugby league players during competitive home match play was assessed throughout the 2008 Super League season. Fourteen players from 2 Super League clubs were monitored (72 observations). On arrival, 2 h prior to kick off, following normal prematch routines, players' body mass were measured following a urine void. Prematch fluid intake, urine output, and osmolality were assessed until kick off, with additional measurements at half time. Fluid intake was also monitored during match play for club B only, and final measurements of variables were made at the end of the match. Mean body mass loss per match was 1.28 ± 0.7 kg (club A, 1.15 kg; club B, 1.40 kg), which would equate to an average level of dehydration of 1.31% (mass loss, assumed to be water loss, expressed as a percentage of body mass), with considerable intra-individual coefficient of variation (CV, 47%). Mean fluid intake for club B was 0.64 ± 0.5 L during match play, while fluid loss was 2.0 ± 0.7 L, with considerable intra-individual CV (51% and 34%, respectively). Mean urine osmolality was 396 ± 252 mosm·kg-1 on arrival, 237 ± 177 mosm·kg-1 prematch, 315 ± 133 mosm·kg-1 at half time, and 489 ± 150 mosm·kg-1 postmatch. Body mass losses were primarily a consequence of body fluid losses not being completely balanced by fluid intake. Furthermore, these data show that there is large inter- and intra-individual variability of hydration across matches, highlighting the need for future assessment of individual relevance.

Purpose To investigate whether there is a differential response at rest and following exercise to conditions of genuine high altitude (GHA), normobaric hypoxia (NH), hypobaric hypoxia (HH) and normobaric normoxia (NN). Method Markers of sympathoadrenal and adrenocortical function (plasma normetanephrine [PNORMET], metanephrine [PMET], cortisol), myocardial injury (highly sensitive cardiac troponin T [hscTnT]) and function (N-terminal brain natriuretic peptide [NT-proBNP]) were evaluated at rest and with exercise under NN, at 3375 m in the Alps (GHA) and at equivalent simulated altitude under NH and HH. Participants cycled for 2 hours {15 minute warm-up, 105 minutes at 55% Wmax (maximal workload)} with venous blood samples taken prior (T0), immediately following (T120) and 2 hours post-exercise (T240). Results Exercise in the three hypoxic environments produced a similar pattern of response with the only difference between environments being in relation to PNORMET. Exercise in NN only induced a rise in PNORMET and PMET. Conclusion Biochemical markers that reflect sympathoadrenal, adrenocortical and myocardial responses to physiological stress demonstrate significant differences in the response to exercise under conditions of normoxia versus hypoxia while NH and HH appear to induce broadly similar responses to GHA and may therefore be reasonable surrogates.

This study compared the effects of co-ingesting glucose and fructose on exogenous and endogenous substrate oxidation during prolonged exercise at altitude and sea level, in men. Seven male British military personnel completed two bouts of cycling at the same relative workload (55% Wmax) for 120 minutes on acute exposure to altitude (3375m) and at sea level (~113m). In each trial, participants ingested 1.2 g.min-1 of glucose (enriched with 13C glucose) and 0.6 g.min-1 of fructose (enriched with 13C fructose) directly before and every 15 minutes during exercise. Indirect calorimetry and isotope ratio mass spectrometry were used to calculate fat oxidation, total and exogenous carbohydrate oxidation, plasma glucose oxidation and endogenous glucose oxidation derived from liver and muscle glycogen. Total carbohydrate oxidation during the exercise period was lower at altitude (157.7±56.3 grams) than sea level (286.5±56.2 grams, P=0.006, ES=2.28), whereas fat oxidation was higher at altitude (75.5±26.8 grams) than sea level (42.5±21.3 grams, P=0.024, ES=1.23). Peak exogenous carbohydrate oxidation was lower at altitude (1.13±0.2 g.min-1) than sea level (1.42±0.16 g.min-1, P=0.034, ES=1.33). There were no differences in rates, or absolute and relative contributions of plasma or liver glucose oxidation between conditions during the second hour of exercise. However, absolute and relative contributions of muscle glycogen during the second hour were lower at altitude (29.3±28.9 grams, 16.6±15.2%) than sea level (78.7±5.2 grams (P=0.008, ES=1.71), 37.7±13.0% (P=0.016, ES=1.45). Acute exposure to altitude reduces the reliance on muscle glycogen and increases fat oxidation during prolonged cycling in men, compared with sea level.

Purpose: This study compared the co-ingestion of glucose and fructose on exogenous and endogenous substrate oxidation during prolonged exercise at terrestrial high altitude (HA) versus sea level, in women. Method: Five women completed two bouts of cycling at the same relative workload (55% Wmax) for 120 minutes on acute exposure to HA (3375m) and at sea level (~113m). In each trial, participants ingested 1.2 g.min-1 of glucose (enriched with 13C glucose) and 0.6 g.min-1 of fructose (enriched with 13C fructose) before and every 15 minutes during exercise. Indirect calorimetry and isotope ratio mass spectrometry were used to calculate fat oxidation, total and exogenous carbohydrate oxidation, plasma glucose oxidation and endogenous glucose oxidation derived from liver and muscle glycogen. Results: The rates and absolute contribution of exogenous carbohydrate oxidation was significantly lower at HA compared with sea level (ES>0.99, P<0.024), with the relative exogenous carbohydrate contribution approaching significance (32.6±6.1 vs. 36.0±6.1%, ES=0.56, P=0.059) during the second hour of exercise. In comparison, no significant differences were observed between HA and sea level for the relative and absolute contributions of liver glucose (3.2±1.2 vs. 3.1±0.8%, ES=0.09, P=0.635 and 5.1±1.8 vs. 5.4±1.7 grams, ES=0.19, P=0.217), and muscle glycogen (14.4±12.2% vs. 15.8±9.3%, ES=0.11, P=0.934 and 23.1±19.0 vs. 28.7±17.8 grams, ES=0.30, P=0.367). Furthermore, there was no significant difference in total fat oxidation between HA and sea level (66.3±21.4 vs. 59.6±7.7 grams, ES=0.32, P=0.557). Conclusion: In women, acute exposure to HA reduces the reliance on exogenous carbohydrate oxidation during cycling at the same relative exercise intensity.