Physical activity, inactivity and sleep in older patients with coronary artery disease following percutaneous coronary intervention: a longitudinal, observational study

OBJECTIVES

Physical activity presents an important cornerstone in the management and care of coronary artery disease (CAD) patients following percutaneous coronary intervention (PCI) and research in older patients continues to be overlooked. This study evaluated differences in physical activity, inactivity and sleep of CAD patients following PCI for acute coronary syndrome consisting of ST-segment elevation myocardial infarction (STEMI) and non-STEMI (NSTEMI) and elective admission of stable angina patients over 12 months.

METHODS

This was an observational, longitudinal study. Fifty-eight patients were recruited (STEMI, n  = 20, NSTEMI, n  = 18 and stable angina, n  = 20) and completed 7-day monitoring (physical activity, inactivity and sleep) using wrist-worn tri-axial accelerometers (GENEActiv, ActivInsights Ltd, Kimbolton, Cambridgeshire, UK) upon discharge from a tertiary centre and repeated measurements at 3 months ( n  = 43), 6 months ( n  = 40) and 12 months ( n  = 33).

RESULTS

Following PCI, CAD patients showed a general trend of increasing light and moderate-vigorous physical activity over the 12-month follow-up. Time in inactivity remained high but decreased over time. Sleep duration and sleep efficiency remained consistent. NSTEMI patients spent less time asleep, more time inactive and less time in light and moderate-vigorous physical activity in comparison to STEMI and stable angina patients. Differences between the groups over time were minimal.

CONCLUSION

These findings suggest that older patients with CAD spend long periods in inactivity but the increasing trend of both light and moderate-vigorous physical activity over time presents a positive change in behaviour in the year following PCI.

Movement as medicine for cardiovascular disease prevention: A pilot feasibility study of a physical activity promotion intervention for at-risk patients in primary care (Preprint)

Background

Objective

Methods

Results

Conclusions

Trial Registration

Assessing the feasibility and acceptability of Changing Health for the management of prediabetes: protocol for a pilot study of a digital behavioural intervention

Background

The prevalence of prediabetes is rapidly rising in the UK, largely associated with an increase in obesity. Lifestyle programmes that provide support to make and sustain dietary and physical activity behavioural changes are necessary to initiate and maintain weight loss. However, these programmes are often intensive and time consuming. Given the magnitude of the problem, there is a need for behavioural interventions that can be delivered at scale. Digital interventions can address some of the aforementioned issues. The primary aim of the present study is to assess the feasibility and acceptability of a digital intervention called Changing Health that provides structured education and lifestyle behaviour change support to adults with prediabetes.

Methods

A single-group pilot study will be undertaken. We aim to recruit 40 participants with prediabetes defined by HbA1c or fasting plasma glucose (FPG), aged between 18 and 75 years with a BMI ≥ 25. Participants will receive the digital intervention (a mobile phone app incorporating structured education and behavioural tools to support lifestyle behaviour change) with the aim of losing and maintaining 5–6% of their baseline body weight. Each participant will receive 100 min of lifestyle coaching over the 9-month intervention period and will have continued access to the digital intervention. Clinical outcome measures will be collected during four visits to our clinical research facility: two visits at baseline, one visit at month 3, and one visit at month 9. These secondary outcome measures will include diet, physical activity, sleep, metabolic control, body composition, cardiorespiratory fitness, and cardiovascular function. To measure primary outcomes, an embedded qualitative study will be conducted to obtain data on feasibility and acceptability of the intervention.

Discussion

This pilot study will establish whether Changing Health is feasible and acceptable to adults with prediabetes. Clinical outcome measures will provide estimates of variability to inform sample size calculations, and qualitative data generated will inform any necessary refinements to the intervention. This will provide a platform for a larger evaluation to assess the effectiveness of Changing Health for changing diet and physical activity to initiate and maintain weight loss in adults with prediabetes.

Trial registration

ISRCTN Registry: ISRCTN69270299.

The degree of hepatic steatosis associates with impaired cardiac and autonomic function

BACKGROUND & AIMS

Cardiovascular disease is the principle cause of death in patients with elevated liver fat unrelated to alcohol consumption, more so than liver-related morbidity and mortality. The aim of this study was to evaluate the relationship between liver fat and cardiac and autonomic function, as well as to assess how impairment in cardiac and autonomic function is influenced by metabolic risk factors.

METHODS

Cardiovascular and autonomic function were assessed in 96 sedentary individuals: i) non-alcoholic fatty liver disease (NAFLD) (n = 46, hepatic steatosis >5% by magnetic resonance spectroscopy), ii) Hepatic steatosis and alcohol (dual aetiology fatty liver disease [DAFLD]) (n = 16, hepatic steatosis >5%, consuming >20 g/day of alcohol) and iii) CONTROL (n = 34, no cardiac, liver or metabolic disorders, <20 g/day of alcohol).

RESULTS

Patients with NAFLD and DAFLD had significantly impaired cardiac and autonomic function when compared with controls. Diastolic variability and systolic variability (LF/HF-sBP [n/1]; 2.3 (1.7) and 2.3 (1.5) vs. 3.4 (1.5), p <0.01) were impaired in patients with NAFLD and DAFLD when compared to controls, with DAFLD individuals showing a decrease in diastolic variability relative to NAFLD patients. Hepatic steatosis and fasting glucose were negatively correlated with stroke volume index. Fibrosis stage was significantly negatively associated with mean blood pressure (r = -0.47, p = 0.02), diastolic variability (r = -0.58, p ≤0.01) and systolic variability (r = -0.42, p = 0.04). Hepatic steatosis was independently associated with cardiac function (p ≤0.01); TNF-α (p ≤0.05) and CK-18 (p ≤0.05) were independently associated with autonomic function.

CONCLUSION

Cardiac and autonomic impairments appear to be dependent on level of liver fat, metabolic dysfunction, inflammation and fibrosis staging, and to a lesser extent alcohol intake. Interventions should be sought to moderate the excess cardiovascular risk in patients with NAFLD or DAFLD.

LAY SUMMARY

Increased levels of fat in the liver impair the ability of the cardiovascular system to work properly. The amount of fat in the liver, metabolic control, inflammation and alcohol are all linked to the degree that the cardiovascular system is affected.

High intensity interval training protects the heart during increased metabolic demand in patients with type 2 diabetes: a randomised controlled trial

AIM

The present study assessed the effect of high intensity interval training on cardiac function during prolonged submaximal exercise in patients with type 2 diabetes.

METHODS

Twenty-six patients with type 2 diabetes were randomized to a 12 week of high intensity interval training (3 sessions/week) or standard care control group. All patients underwent prolonged (i.e. 60 min) submaximal cardiopulmonary exercise testing (at 50% of previously assess maximal functional capacity) with non-invasive gas-exchange and haemodynamic measurements including cardiac output and stroke volume before and after the intervention.

RESULTS

At baseline (prior to intervention) there was no significant difference between the intervention and control group in peak exercise oxygen consumption (20.3 ± 6.1 vs. 21.7 ± 5.5 ml/kg/min, p = 0.21), and peak exercise heart rate (156.3 ± 15.0 vs. 153.8 ± 12.5 beats/min, p = 0.28). During follow-up assessment both groups utilized similar amount of oxygen during prolonged submaximal exercise (15.0 ± 2.4 vs. 15.2 ± 2.2 ml/min/kg, p = 0.71). However, cardiac function i.e. cardiac output during submaximal exercise decreased significantly by 21% in exercise group (16.2 ± 2.7-12.8 ± 3.6 L/min, p = 0.03), but not in the control group (15.7 ± 4.9-16.3 ± 4.1 L/min, p = 0.12). Reduction in exercise cardiac output observed in the exercise group was due to a significant decrease in stroke volume by 13% (p = 0.03) and heart rate by 9% (p = 0.04).

CONCLUSION

Following high intensity interval training patients with type 2 diabetes demonstrate reduced cardiac output during prolonged submaximal cardiopulmonary exercise testing. Ability of patients to maintain prolonged increased metabolic demand but with reduced cardiac output suggests cardiac protective role of high intensity interval training in type 2 diabetes.

TRIAL REGISTRATION

ISRCTN78698481. Registered 23 January 2013, retrospectively registered.

Unsupervised high-intensity interval training improves glycaemic control but not cardiovascular autonomic function in type 2 diabetes patients: A randomised controlled trial

BACKGROUND

This is the first randomised controlled trial to assess the impact of unsupervised high-intensity interval training on cardiovascular autonomic function in adults with type 2 diabetes.

METHODS

A total of 22 individuals with type 2 diabetes (age 60 ± 2 years, 17 males) lay in a supine position for 20 min for evaluation of cardiovascular autonomic function, which included (1) time domain measures of heart rate variability, (2) frequency domain measures of heart rate variability and blood pressure variability and (3) baroreflex receptor sensitivity. Participants were randomised into 12 weeks of high-intensity interval training (3 sessions/week) or standard care control group.

RESULTS

After 12 weeks, the between-group change in HbA1c (%) was significant (high-intensity interval training: 7.13 ± 0.31 to 6.87 ± 0.29 vs Control: 7.18 ± 0.17 to 7.36 ± 0.21, p = 0.03). There were no significant changes in measures of heart rate variability; R-R interval (ms) (high-intensity interval training: 954 ± 49 to 973 ± 53 vs Control: 920 ± 6 to 930 ± 32, p = 0.672), low frequency/high frequency (high-intensity interval training: 0.90 ± 0.21 to 0.73 ± 0.07 vs Control: 1.20 ± 0.29 to 1.00 ± 0.17, p = 0.203), or blood pressure variability; systolic blood pressure low frequency/high frequency (high-intensity interval training: 0.86 ± 0.21 to 0.73 ± 0.10 vs Control: 1.06 ± 0.26 to 0.91 ± 0.14, p = 0.169). At baseline, HbA1c was negatively correlated with baroreflex receptor sensitivity ( r = -0.592, p < 0.01).

CONCLUSION

High-intensity interval training improves glycaemic control but has limited effect on cardiovascular autonomic regulation in patients with type 2 diabetes.

Adiposity predicts low cardiorespiratory fitness in individuals with metabolic diseases

Cardiorespiratory fitness (CRF) is impaired in those with metabolic diseases and strongly predicts mortality. We found that adiposity, not glycaemic control or disease type, is the strongest predictor of low CRF in those with metabolic diseases. We discuss how adiposity and metabolic health may relate to outcomes in obesity.

Accelerometer-derived physical activity in those with cardio-metabolic disease compared to healthy adults: a UK Biobank study of 52,556 participants

AIM

Cardio-metabolic disease and physical activity are closely related but large-scale objective studies which measure physical activity are lacking. Using the largest accelerometer cohort to date, we aimed to investigate whether there is an association between disease status and accelerometer variables after a 5-year follow-up.

METHODS

106,053 UK Biobank participants wore a wrist-worn GENEactiv monitor. Those with acceptable wear time (> 3 days) were split into 4 cardio-metabolic disease groups based on self-report disease status which was collected 5 ± 1 years prior. Multiple linear regression models were used to investigate associations, controlling for confounders and stratified for gender.

RESULTS

Average daily acceleration was lower in men ('healthy'-42 ± 15 mg v 'Type 2 diabetes + cardiovascular disease (CVD)'-31 ± 12 mg) and women ('healthy'-44 ± 13 mg v 'Type 2 diabetes + CVD'-31 ± 11 mg) with cardio-metabolic disease and this was consistent across both week and weekend days. Men and women with the worst cardio-metabolic disease perform around half of moderate to vigorous physical activity on a daily basis compared to healthy individuals, and spend almost 7 h per day in 30 min inactivity bouts. Significant associations were seen between cardio-metabolic disease and accelerometer variables 5 years on when controlling for confounders.

CONCLUSION

In the largest accelerometer cohort to date, there are significant associations between cardio-metabolic disease and physical activity variables after 5 years of follow-up. Triaxial accelerometers provide enhanced measurement opportunities for measuring lifestyle behaviours in chronic disease.

Estimating sleep parameters using an accelerometer without sleep diary

Wrist worn raw-data accelerometers are used increasingly in large-scale population research. We examined whether sleep parameters can be estimated from these data in the absence of sleep diaries. Our heuristic algorithm uses the variance in estimated z-axis angle and makes basic assumptions about sleep interruptions. Detected sleep period time window (SPT-window) was compared against sleep diary in 3752 participants (range = 60-82 years) and polysomnography in sleep clinic patients (N = 28) and in healthy good sleepers (N = 22). The SPT-window derived from the algorithm was 10.9 and 2.9 minutes longer compared with sleep diary in men and women, respectively. Mean C-statistic to detect the SPT-window compared to polysomnography was 0.86 and 0.83 in clinic-based and healthy sleepers, respectively. We demonstrated the accuracy of our algorithm to detect the SPT-window. The value of this algorithm lies in studies such as UK Biobank where a sleep diary was not used.

Systematic review assessing the effectiveness of dietary intervention on gut microbiota in adults with type 2 diabetes

AIMS/HYPOTHESIS

Despite improved understanding of the pathophysiology of type 2 diabetes mellitus, explanations for individual variability in disease progression and response to treatment are incomplete. The gut microbiota has been linked to the pathophysiology of type 2 diabetes mellitus and may account for this variability. We conducted a systematic review to assess the effectiveness of dietary and physical activity/exercise interventions in modulating the gut microbiota and improving glucose control in adults with type 2 diabetes mellitus.

METHODS

A systematic search was conducted to identify studies reporting on the effect of dietary and physical activity/exercise interventions on the gut microbiota and glucose control in individuals with a confirmed diagnosis of type 2 diabetes mellitus. Study characteristics, methodological quality and details relating to interventions were captured using a data-extraction form. Meta-analyses were conducted where sufficient data were available, and other results were reported narratively.

RESULTS

Eight studies met the eligibility criteria of the systematic review. No studies were found that reported on the effects of physical activity/exercise on the gut microbiota and glucose control. However, studies reporting on dietary interventions showed that such interventions were associated with modifications to the composition and diversity of the gut microbiota. There was a statistically significant improvement in HbA_1c (standardised mean difference [SMD] -2.31 mmol/mol [95% CI -2.76, -1.85] [0.21%; 95% CI -0.26, -0.16]; I² = 0%, p < 0.01), but not in fasting blood glucose (SMD -0.25 mmol/l [95% CI -0.85, 0.35], I² = 87%, p > 0.05), fasting insulin (SMD -1.82 pmol/l [95% CI -7.23, 3.60], I² = 54%, p > 0.05) or HOMA-IR (SMD -0.15 [95% CI -0.63, 0.32], I² = 69%, p > 0.05) when comparing dietary interventions with comparator groups. There were no significant changes in the relative abundance of bacteria in the genera Bifidobacterium (SMD 1.29% [95% CI -4.45, 7.03], I² = 33%, p > 0.05), Roseburia (SMD -0.85% [95% CI -2.91, 1.21], I² = 79%, p > 0.05) or Lactobacillus (SMD 0.04% [95% CI -0.01, 0.09], I² = 0%, p > 0.05) when comparing dietary interventions with comparator groups. There were, however, other significant changes in the gut microbiota, including changes at various taxonomic levels, including phylum, family, genus and species, Firmicutes:Bacteroidetes ratios and changes in diversity matrices (α and β). Dietary intervention had minimal or no effect on inflammation, short-chain fatty acids or anthropometrics.

CONCLUSIONS/INTERPRETATION

Dietary intervention was found to modulate the gut microbiota and improve glucose control in individuals with type 2 diabetes. Although the results of the included studies are encouraging, this review highlights the need for further well-conducted interventional studies to inform the clinical use of dietary interventions targeting the gut microbiota.

Skeletal muscle mitochondrial oxidative phosphorylation function in idiopathic pulmonary arterial hypertension: in vivo and in vitro study

Mitochondrial dysfunction within the pulmonary vessels has been shown to contribute to the pathology of idiopathic pulmonary arterial hypertension (IPAH). We investigated the hypothesis of whether impaired exercise capacity observed in IPAH patients is in part due to primary mitochondrial oxidative phosphorylation (OXPHOS) dysfunction in skeletal muscle. This could lead to potentially new avenues of treatment beyond targeting the pulmonary vessels. Nine clinically stable participants with IPAH underwent cardiopulmonary exercise testing, in vivo and in vitro assessment of mitochondrial function by ³¹P-magnetic resonance spectroscopy (³¹P-MRS) and laboratory muscle biopsy analysis. ³¹P-MRS showed abnormal skeletal muscle bioenergetics with prolonged recovery times of phosphocreatine and abnormal muscle pH handling. Histochemistry and quadruple immunofluorescence performed on muscle biopsies showed normal function and subunit protein abundance of the complexes within the OXPHOS system. Our findings suggest that there is no primary mitochondrial OXPHOS dysfunction but raises the possibility of impaired oxygen delivery to the mitochondria affecting skeletal muscle bioenergetics during exercise.

Impact of Age-Related Mitochondrial Dysfunction and Exercise on Intestinal Microbiota Composition

Mitochondrial dysfunction is prevalent in the aging gastrointestinal tract. We investigated whether mitochondrial function in aging colonic crypts and exercise influences microbial gut communities in mice. Twelve PolgAmut/mut mice were randomly divided into a sedentary and exercise group at 4 months. Seven-aged matched PolgA+/+ mice remained sedentary throughout. Stool samples were collected at 4, 7, and 11 months, and bacterial profiling was achieved through 16S rRNA sequencing profiling. Mitochondrial enzyme activity was assessed in colonic epithelial crypts at 11 months for PolgAmut/mut and PolgA+/+ mice. Sedentary and exercised PolgAmut/mut mice had significantly higher levels of mitochondrial dysfunction than PolgA+/+ mice (78%, 77%, and 1% of crypts, respectively). Bacterial profiles of sedentary PolgAmut/mut mice were significantly different from the sedentary PolgA+/+ mice, with increases in Lactobacillus and Mycoplasma, and decreases in Alistipes, Odoribacter, Anaeroplasma, Rikenella, Parabacteroides, and Allobaculum in the PolgAmut/mut mice. Exercise did not have any impact upon gut mitochondrial dysfunction; however, exercise did increase gut microbiota diversity and significantly increased bacterial genera Mucispirillum and Desulfovibrio. Mitochondrial dysfunction is associated with changes in the gut microbiota. Endurance exercise moderated some of these changes, establishing that environmental factors can influence gut microbiota, despite mitochondrial dysfunction.

Age-related decline in cardiac autonomic function is not attenuated with increased physical activity

Age and physical inactivity are important risk factors for cardiovascular mortality. Heart rate response to exercise (HRRE) and heart rate recovery (HRR), measures of cardiac autonomic function, are strong predictors of mortality. The present study defined the effect of age and physical activity on HRRE and HRR. Healthy women (N=72) grouped according to age (young, 20-30 years; middle, 40-50 years; and older, 65-81 years) and daily physical activity (low active <7500, high active >12,500 steps/day) performed a maximal cardiopulmonary exercise test. The HRRE was defined as an increase in heart rate from rest to 1, 3 and 5 minutes of exercise and at 1/3 of total exercise time, and HRR as the difference in heart rate between peak exercise and 1, 2, and 3 minutes later. Age was associated with a significant decline in HRRE at 1 min and 1/3 of exercise time (r= − 0.27, p=0.04, and r=−0.39, p=0.02) and HRR at 2 min and 3 min (r=−0.35, p=0.01, and r=−0.31, p=0.02). There was no significant difference in HRRE and HRR between high and low-active middle-age and older women (p>0.05). Increased level of habitual physical activity level appears to have a limited effect on age-related decline in cardiac autonomic function in women.

The cardio-metabolic impact of taking commonly prescribed analgesic drugs in 133,401 UK Biobank participants

Objective

There has been a significant increase in the prescribing of medication for chronic non-cancer pain. In a UK population sample, we aimed to assess cardio-metabolic (CM) health in those taking these chronic pain medications.

Methods

133,401 participants from the UK Biobank cohort were studied. BMI, waist cm and hypertension were compared between those on drugs prescribed for chronic pain and CM drugs to those on CM drugs only. Multiple confounders were controlled for.

Results

Those taking opiates and CM drugs had the worst CM health profile with a 95%, 82% and 63% increased odds of reporting obesity, ‘very high risk’ waist circumference and hypertension, respectively (OR [95% CI] 1.95 [1.75–2.17], 1.82 [1.63–2.03], 1.63 [1.45–1.84]), compared to those on CM drugs alone. Those taking neuropathic pain medications and CM drugs also demonstrate worse CM profile than those taking CM drugs only.

Conclusions

The impact of medications for chronic pain and sleep upon CM health and obesity is of concern for these classes of drugs which have been recently labelled as dependency forming medications. The results from this cross sectional study warrants further investigation and adds further support to calls for these medications to be prescribed for shorter periods.

Effects of Exercise on Liver Fat and Metabolism in Alcohol Drinkers

BACKGROUND & AIMS

Exercise is an important component of obesity-associated disorders and has been shown to reduce markers of nonalcoholic fatty liver disease (NAFLD). However, little is known about how these effects are influenced by alcohol intake. The authors performed a randomized controlled trial to investigate the effects of exercise on hepatic triglyceride content (HTGC) and metabolism in overweight or obese patients who consume alcohol.

METHODS

The authors performed a prospective study of 27 patients (mean 54 ± 11 years of age, body mass index [BMI] 31 ± 4 kg/m²) with >5% HTGC in the United Kingdom, consuming alcohol (mean 221 ± 75 g/week). Anthropometry, body composition, HTGC, and abdominal fat were measured using plethysmography and magnetic resonance imaging. Subjects were assigned to groups that exercised (3 times/week on nonconsecutive days) for 12 weeks (n = 14) or continued standard care (control group, n = 13), maintaining baseline weight and alcohol consumption. The exercise program consisted of aerobic exercise (static cycling) and a circuit of resistance exercise (free weights and machines). Patients were examined at baseline and at 12 weeks; data collected on HTGC, body composition, metabolic control, circulating inflammatory, and fibrosis markers were assessed at baseline and at 12 weeks. Between-group differences were evaluated using an unpaired t test and within-group differences using a paired t test. The primary outcomes for this study were changes in HTGC between baseline and 12 weeks.

RESULTS

After 12 weeks, there was no significant difference between the exercise and control groups in HTGC (reduction of 0.1% ± 2.1% in exercisers vs increase of 0.5 ± 2.1% in control group; P > .05). At week 12, the exercise group had significant reductions in subcutaneous fat (loss of 23 ± 28 cm² in the exercisers vs increase of 12 ± 19 cm² in the control group; P < .01), and whole body fat (loss of 2.1 ± 1.1 kg in the exercisers vs increase of 0.2 ± 2.1 kg; P < .01). The exercise group also had a significantly greater increase in lean body mass (increase of 1.9 ± 1.4 kg for the exercisers vs increase of 0.7 ± 1.5 kg for the control group; P < .01) and a significantly greater reduction in level of cytokeratin 18 (reduction of 49 ± 82 U/L in exercisers vs increase of 17 ± 38 U/L in control group; P < .05). There were no differences between groups in changes in metabolic factors or markers of inflammation.

CONCLUSIONS

In a randomized controlled trial of obese individuals who consume alcohol, exercise significantly improved body composition and reduced hepatocyte apoptosis (cytokeratin 18), but did not reduce HTGC. This finding could indicate that alcohol consumption reduces the effects of exercise on NAFLD observed in previous studies. Clinical care teams should look to use exercise as part of the management strategy for people consuming alcohol, but optimal benefit may be as an adjunct to alcohol reduction and weight management strategies. (ISRCTN.com, Number: ISRCTN90597099).

A study of physical activity comparing people with Charcot-Marie-Tooth disease to normal control subjects

PURPOSE

Charcot Marie Tooth disease (CMT) describes a group of hereditary neuropathies that present with distal weakness, wasting and sensory loss. Small studies indicate that people with CMT have reduced daily activity levels. This raises concerns as physical inactivity increases the risk of a range of co- morbidities, an important consideration in the long-term management of this disease. This study aimed to compare physical activity, patterns of sedentary behavior and overall energy expenditure of people with CMT and healthy matched controls.

METHODS

We compared 20 people with CMT and 20 matched controls in a comparison of physical activity measurement over seven days, using an activity monitor. Patterns of sedentary behavior were explored through a power law analysis.

RESULTS

Results showed a decrease in daily steps taken in the CMT group, but somewhat paradoxically, they demonstrate shorter bouts of sedentary activity and more frequent transitions from sedentary to active behaviors. No differences were seen in energy expenditure or time spent in sedentary, moderate or vigorous activity.

CONCLUSION

The discrepancy between energy expenditure and number of steps could be due to higher energy requirements for walking, but also may be due to an over-estimation of energy expenditure by the activity monitor in the presence of muscle wasting. Alternatively, this finding may indicate that people with CMT engage more in activities or movement not related to walking. Implications for Rehabilitation Charcot-Marie-Tooth disease: • People with Charcot-Marie-Tooth disease did not show a difference in energy expenditure over seven days compared to healthy controls, but this may be due to higher energy costs of walking, and/or an over estimation of energy expenditure by the activity monitor in a population where there is muscle wasting. This needs to be considered when interpreting activity monitor data in people with neuromuscular diseases. • Compared to healthy controls, people with Charcot-Marie-Tooth disease had a lower step count over seven days, but exhibited more frequent transitions from sedentary to active behaviors • High Body Mass Index and increased time spent sedentary were related factors that have implications for general health status. • Understanding the profile of physical activity and behavior can allow targeting of rehabilitation interventions to address mobility and fitness.

Pathophysiology of exercise intolerance in chronic diseases: the role of diminished cardiac performance in mitochondrial and heart failure patients

Objective

Exercise intolerance is a clinical hallmark of chronic conditions. The present study determined pathophysiological mechanisms of exercise intolerance in cardiovascular, neuromuscular, and metabolic disorders.

Methods

In a prospective cross-sectional observational study 152 patients (heart failure reduced ejection fraction, n=32; stroke, n=34; mitochondrial disease, n=28; type two diabetes, n=28; and healthy controls, n=30) performed cardiopulmonary exercise testing with metabolic and haemodynamic measurements. Peak exercise O₂ consumption and cardiac power output were measures of exercise tolerance and cardiac performance.

Results

Exercise tolerance was significantly diminished in patients compared with controls (ie, by 45% stroke, 39% mitochondria disease, and 33% diabetes and heart failure, p<0.05). Cardiac performance was only significantly reduced in heart failure (due to reduced heart rate, stroke volume, and blood pressure) and mitochondrial patients (due reduced stroke volume) compared with controls (ie, by 53% and 26%, p<0.05). Ability of skeletal muscles to extract oxygen (ie, arterial-venous O₂ difference) was diminished in mitochondrial, stroke, and diabetes patients (by 24%, 22%, and 18%, p<0.05), but increased by 21% in heart failure (p<0.05) compared with controls. Cardiac output explained 65% and 51% of the variance in peak O₂ consumption (p<0.01) in heart failure and mitochondrial patients, whereas arterial-venous O₂ difference explained 69% (p<0.01) of variance in peak O₂ consumption in diabetes, and 65% and 48% in stroke and mitochondrial patients (p<0.01).

Conclusions

Different mechanisms explain exercise intolerance in patients with heart failure, mitochondrial dysfunction, stroke and diabetes. Their better understanding may improve management of patients, their stress tolerance and quality of life.

Impact of age on the association between cardiac high-energy phosphate metabolism and cardiac power in women

OBJECTIVE

Diminished cardiac high-energy phosphate metabolism (phosphocreatine-to-ATP (PCr:ATP) ratio) and cardiac power with age may play an important roles in development of cardiac dysfunction and heart failure. The study defines the impact of age on PCr:ATP ratio and cardiac power and their relationship.

METHODS

Thirty-five healthy women (young≤50 years, n=20; and old≥60 years, n=15) underwent cardiac MRI with ³¹P spectroscopy to assess PCr:ATP ratio and performed maximal graded cardiopulmonary exercise testing with simultaneous gas-exchange and central haemodynamic measurements. Peak cardiac power output, as the best measure of pumping capability and performance of the heart, was calculated as the product of peak exercise cardiac output and mean arterial blood pressure.

RESULTS

PCr:ATP ratio was significantly lower in old compared with young age group (1.92±0.48 vs 2.29±0.55, p=0.03), as were peak cardiac power output (3.35±0.73 vs 4.14±0.81W, p=0.01), diastolic function (ie, early-to-late diastolic filling ratio, 1.33±0.54 vs 3.07±1.84, p<0.01) and peak exercise oxygen consumption (1382.9±255.0 vs 1940.3±434.4 mL/min, p<0.01). Further analysis revealed that PCr:ATP ratio shows a significant positive relationship with early-to-late diastolic filling ratio (r=0.46, p=0.02), peak cardiac power output (r=0.44, p=0.02) and peak oxygen consumption (r=0.51, p=0.01).

CONCLUSIONS

High-energy phosphate metabolism and peak power of the heart decline with age. Significant positive relationship between PCr:ATP ratio, early-to-late diastolic filling ratio and peak cardiac power output suggests that cardiac high-energy phosphate metabolism may be an important determinant of cardiac function and performance.

Low physical activity, high television viewing and poor sleep duration cluster in overweight and obese adults; a cross-sectional study of 398,984 participants from the UK Biobank

BACKGROUND

An unhealthy lifestyle is one of the greatest contributors to obesity. A number of behaviours are linked with obesity, but are often measured separately. The UK Biobank cohort of >500,000 participants allows us to explore these behaviours simultaneously. We therefore aimed to compare physical activity, television (TV) viewing and sleep duration across body mass index (BMI) categories in a large sample of UK adults.

METHODS

UK Biobank participants were recruited and baseline measures were taken between 2007 and 2010 and data analysis was performed in 2015. BMI was measured objectively using trained staff. Self-report questionnaires were used to measure lifestyle behaviours including the international physical activity questionnaire (IPAQ-short form) for physical activity. During data analysis, six groups were defined based on BMI; 'Underweight' (n = 2026), 'Normal weight' (n = 132,372), 'Overweight (n = 171,030), 'Obese I' (n = 67,903), 'Obese II' (n = 18,653) and 'Obese III' (n = 7000). The odds of reporting unhealthy lifestyle behaviours (low physical activity, high TV viewing or poor sleep duration) were compared across BMI groups using logistic regression analysis.

RESULTS

Overweight and obese adults were more likely to report low levels of physical activity (≤967.5 MET.mins/wk) ('Overweight'-OR [95% CI]: 1.23 [1.20 to 1.26], 'Obese I' 1.66 [1.61-1.71], 'Obese II' 2.21 [2.12-2.30], and 'Obese III' 3.13 [2.95 to 3.23]) compared to 'Normal weight' adults. The odds of reporting high TV viewing (3 h/day) was greater in 'Overweight' (1.52 [1.48 to 1.55]) and obese adults ('Obese I' 2.06 [2.00-2.12], 'Obese II' 2.69 [2.58-2.80], 'Obese III' 3.26 [3.07 to 3.47]), and poor sleep duration (<7, >8 h/night) was higher in 'Overweight' (1.09 [1.07 to 1.12]) and obese adults ('Obese I' 1.31 [1.27-1.34], 'Obese II' 1.50 [1.44-1.56], 'Obese III' (1.78 [1.68 to 1.89]) compared to the 'Normal weight' group. These lifestyle behaviours were clustered, the odds of reporting simultaneous low physical activity, high TV viewing and poor sleep (unhealthy behavioural phenotype) was higher than reporting these behaviours independently, in overweight and obese groups. 'Obese III' adults were almost six times more likely (5.47 [4.96 to 6.05]) to report an unhealthy behavioural phenotype compared to the 'Normal weight' group.

CONCLUSIONS

Overweight and obese adults report low levels of physical activity, high TV viewing and poor sleep duration. These behaviours seem to cluster and collectively expose individuals to greater risk of obesity. Multiple lifestyle behaviours should be targeted in future interventions.

Large Scale Population Assessment of Physical Activity Using Wrist Worn Accelerometers: The UK Biobank Study

Background

Physical activity has not been objectively measured in prospective cohorts with sufficiently large numbers to reliably detect associations with multiple health outcomes. Technological advances now make this possible. We describe the methods used to collect and analyse accelerometer measured physical activity in over 100,000 participants of the UK Biobank study, and report variation by age, sex, day, time of day, and season.

Methods

Participants were approached by email to wear a wrist-worn accelerometer for seven days that was posted to them. Physical activity information was extracted from 100Hz raw triaxial acceleration data after calibration, removal of gravity and sensor noise, and identification of wear / non-wear episodes. We report age- and sex-specific wear-time compliance and accelerometer measured physical activity, overall and by hour-of-day, week-weekend day and season.

Results

103,712 datasets were received (44.8% response), with a median wear-time of 6.9 days (IQR:6.5–7.0). 96,600 participants (93.3%) provided valid data for physical activity analyses. Vector magnitude, a proxy for overall physical activity, was 7.5% (2.35mg) lower per decade of age (Cohen’s d = 0.9). Women had a higher vector magnitude than men, apart from those aged 45-54yrs. There were major differences in vector magnitude by time of day (d = 0.66). Vector magnitude differences between week and weekend days (d = 0.12 for men, d = 0.09 for women) and between seasons (d = 0.27 for men, d = 0.15 for women) were small.

Conclusions

It is feasible to collect and analyse objective physical activity data in large studies. The summary measure of overall physical activity is lower in older participants and age-related differences in activity are most prominent in the afternoon and evening. This work lays the foundation for studies of physical activity and its health consequences. Our summary variables are part of the UK Biobank dataset and can be used by researchers as exposures, confounding factors or outcome variables in future analyses.

High-intensity interval training: a review of its impact on glucose control and cardiometabolic health

Exercise plays a central role in the management and treatment of common metabolic diseases, but modern society presents many barriers to exercise. Over the past decade there has been considerable interest surrounding high-intensity interval training (HIIT), with advocates claiming it can induce health benefits of similar, if not superior magnitude to moderate-intensity continuous exercise, despite reduced time commitment. As the safety of HIIT becomes clearer, focus has shifted away from using HIIT in healthy individuals towards using this form of training in clinical populations. The continued growth of metabolic disease and reduced physical activity presents a global health challenge and effective therapies are urgently required. The aim of this review is to explore whether the acclaim surrounding HIIT is justified by examining the effect of HIIT on glucose control, its ability to affect cardiovascular function and the underlying mechanisms of the changes observed in those with common metabolic diseases. It also explores translation of the research into clinical practice.

Exercise Reduces Liver Lipids and Visceral Adiposity in Patients With Nonalcoholic Steatohepatitis in a Randomized Controlled Trial

BACKGROUND & AIMS

Pharmacologic treatments for nonalcoholic steatohepatitis (NASH) are limited. Lifestyle interventions are believed to be effective in reducing features of NASH, although the effect of regular exercise, independent of dietary change, is unclear. We performed a randomized controlled trial to study the effect of exercise on hepatic triglyceride content (HTGC) and biomarkers of fibrosis in patients with NASH.

METHODS

Twenty-four patients (mean age, 52 ± 14 y; body mass index, 33 ± 6 kg/m²) with sedentary lifestyles (<60 min/wk of moderate-vigorous activity) and biopsy-proven NASH were assigned randomly to groups that exercised (n = 12) or continued standard care (controls, n = 12) for 12 weeks while maintaining their weight. The exercise (cycling and resistance training) was supervised at an accredited sports center and supervised by a certified exercise specialist and recorded 3 times per week on nonconsecutive days. We measured HTGC, body composition, circulating markers of inflammation, fibrosis, and glucose tolerance at baseline and at 12 weeks.

RESULTS

Compared with baseline, exercise significantly reduced HTGC (reduction of 16% ± 24% vs an increase of 9% ± 15% for controls; P < .05), visceral fat (reduction of 22 ± 33 cm² vs an increase of 14 ± 48 cm² for controls; P < .05), plasma triglycerides (reduction of 0.5 ± 1.0 mmol/L vs an increase of 0.3 ± 0.4 mmol/L for controls; P < .05), and γ-glutamyltransferase (reduction of 10 ± 28 U/L^-1 vs a reduction of 17 ± 38 U/L^-1 for controls; P < .05). There were no effects of exercise on liver enzyme levels, metabolic parameters, circulatory markers of inflammation (levels of interleukin 6, tumor necrosis factor-α, or C-reactive protein) and fibrosis.

CONCLUSIONS

In a randomized controlled trial, 12 weeks of exercise significantly reduced HTGC, visceral fat, and plasma triglyceride levels in patients with NASH, but did not affect circulating markers of inflammation or fibrosis. Exercise without weight loss therefore affects some but not all factors associated with NASH. Clinical care teams should consider exercise as part of a management strategy of NASH, but weight management strategies should be included. Larger and longer-term studies are required to determine the effects of exercise in patients with NASH. ISRCTN registry.com: ISRCTN16070927.

Measuring Habitual Physical Activity in Neuromuscular Disorders: A Systematic Review

BACKGROUND

Free-living or habitual physical activity (HPA) refers to someone's performance in his or her free-living environment. Neuromuscular disorders (NMD) manifest through HPA, and the observation of HPA can be used to identify clinical risks and to quantify outcomes in research. This review summarizes and analyses previous studies reporting the assessment of HPA in NMD, and may serve as the basis for evidence-based decision-making when considering assessing HPA in this population.

METHODS

A systematic review was performed to identify all studies related to HPA in NMD, followed by a critical appraisal of the assessment methodology and a final review of the identified HPA tools.

RESULTS

A total of 22 studies were selected, reporting on eight different direct tools (or activity monitors) and ten structured patient-reported outcomes. Overall, HPA patterns in NMD differ from healthy control populations. There was a noticeable lack of validation studies for these tools and outcome measures in NMD. Very little information regarding feasibility and barriers for the application of these tools in this population have been published.

CONCLUSIONS

The variety and heterogeneity of tools and methods in the published literature makes the comparison across different studies difficult, and methodological guidelines are warranted. We propose a checklist of considerations for the assessment and reporting of HPA in NMD.

The effect of percutaneous coronary intervention on habitual physical activity in older patients

BACKGROUND

Given the ongoing burden of cardiovascular disease and an ageing population, physical activity in patients with coronary artery disease needs to be emphasized. This study assessed whether sedentary behaviour and physical activity levels differed among older patients (≥75 years) following percutaneous coronary intervention (PCI) for acute coronary syndrome (ACS) consisting of ST-segment elevation myocardial infarction (STEMI) and non STEMI (NSTEMI) versus an elective admission control group of stable angina patients.

METHODS

Sedentary behaviour and physical activity were assessed over a 7-day period using wrist-worn triaxial accelerometers (GENEActiv, Activinsights Ltd, UK) in 58 patients following PCI for, STEMI (n = 20) NSTEMI (n = 18) and stable angina (n = 20) upon discharge from a tertiary centre. Mean ± Standard deviation age was 79 ± 4 years (31% female).

RESULTS

STEMI and NSTEMI patients spent more time in the low acceleration category (0-40 mg) reflecting sedentary time versus stable angina patients (1298 ± 59 and 1305 ± 66 vs. 1240 ± 92 min/day, p < 0.05). STEMI and NSTEMI patients spent less time in the 40-80 mg acceleration category reflecting low physical activity versus stable angina patients (95 ± 35 and 94 ± 41 vs. 132 ± 50 min/day, p < 0.05). Stable angina patients spent more time in the higher acceleration categories (80-120 and 120-160 mg) and moderate-to-vigorous physical activity (defined as 1 and 5 min/day bouts) versus NSTEMI patients (p < 0.05). For acceleration categories ≥160 mg, no differences were observed.

CONCLUSIONS

Patients presenting with ACS and undergoing PCI spent more time in sedentary behaviour compared with stable angina patients.

Prevalence and risk factors for prolonged QT interval and QT dispersion in patients with type 2 diabetes

AIMS

Prolonged QT interval is associated with cardiac arrhythmias and sudden death. The present study determined the prevalence of prolonged QT interval and QT dispersion and defined their clinical and metabolic predictors in patients with type 2 diabetes.

METHODS

Cross-sectional study included 501 patients with type 2 diabetes. A standard 12-lead electrocardiogram was recorded. QT corrected for heart rate (QTc) >440 ms and QT dispersion (QTd) >80 ms were considered abnormally prolonged. QTc ≥ 500 ms was considered a high-risk QTc prolongation. Demographic, clinical and laboratory data were collected. Independent risk factors for prolonged QTc and QTd were assessed using logistic regression analysis.

RESULTS

Prevalence of QTc > 440 ms and QTd > 80 ms were 44.1 and 3.6 %, respectively. Prevalence of high-risk QTc (≥500 ms) was 2 % only. Independent risk factors for QTc prolongation >440 ms were mean blood glucose (β = 2.192, p < 0.001), treatment with sulphonylurea (β = 5.198, p = 0.027), female gender (β = 8.844, p < 0.001), and coronary heart disease (β = 8.636, p = 0.001). Independent risk factors for QTc ≥ 500 ms were coronary heart disease (β = 4.134, p < 0.001) and mean blood glucose level (β = 1.735, p < 0.001). The independent risk factor for prolonged QTd was only coronary heart disease (β = 5.354, p < 0.001).

CONCLUSIONS

Although the prevalence of prolonged QTc > 440 ms is significant, the prevalence of high-risk QTc (≥500 ms) and QTd > 80 ms is very low in patients with type 2 diabetes. Hyperglycaemia and coronary heart disease are strong predictors of high-risk QTc.

Systematic development of a theory-informed multifaceted behavioural intervention to increase physical activity of adults with type 2 diabetes in routine primary care: Movement as Medicine for Type 2 Diabetes

BACKGROUND

Despite substantial evidence for physical activity (PA) as a management option for type 2 diabetes, there remains a lack of PA behavioural interventions suitable for delivery in primary care. This paper describes the systematic development of an evidence-informed PA behavioural intervention for use during routine primary care consultations.

METHODS

In accordance with the Medical Research Council Framework for the Development and Evaluation of Complex Interventions, a four-stage systematic development process was undertaken: (1) exploratory work involving interviews and workshop discussions identified training needs of healthcare professionals and support needs of adults with type 2 diabetes; (2) a systematic review with meta- and moderator analyses identified behaviour change techniques and optimal intervention intensity and duration; (3) usability testing identified strategies to increase implementation of the intervention in primary care and (4) an open pilot study in two primary care practices facilitated intervention optimisation.

RESULTS

Healthcare professional training needs included knowledge about type, intensity and duration of PA sufficient to improve glycaemic control and acquisition of skills to promote PA behaviour change. Patients lacked knowledge about type 2 diabetes and skills to enable them to make sustainable changes to their level of PA. An accredited online training programme for healthcare professionals and a professional-delivered behavioural intervention for adults with type 2 diabetes were subsequently developed. This multifaceted intervention was informed by the theory of planned behaviour and social cognitive theory and consisted of 15 behaviour change techniques. Intervention intensity and duration were informed by a systematic review. Usability testing resolved technical problems with the online training intervention that facilitated use on practice IT systems. An open pilot study of the intervention with fidelity of delivery assessment informed optimisation and identified mechanisms to enhance implementation of the intervention during routine diabetes consultations.

CONCLUSIONS

Movement as Medicine for Type 2 diabetes represents an evidence-informed multifaceted behavioural intervention targeting PA for management of type 2 diabetes developed for delivery in primary care. The structured development process undertaken enhances transparency of intervention content, replicability and scalability. Movement as Medicine for Type 2 diabetes is currently undergoing evaluation in a pilot RCT.

TRIAL REGISTRATION

ISRCTN67997502.

Exercise therapy in primary biliary cirrhosis: the importance of moving while sitting on a surgical waiting list-a case study

BACKGROUND

It is being increasingly recognised that reduced cardiorespiratory fitness is associated with poorer outcomes after major surgery. Exercise limitation and reduced aerobic capacity are common in people with end-stage liver disease. There is limited evidence about the role of exercise therapy in the management of primary biliary cirrhosis (PBC) and no studies have looked at the effect of exercise in people with PBC who are awaiting liver transplantation. This case study is the first to report that personalised exercise therapy improves cardiorespiratory fitness in a patient with PBC without worsening symptoms of severe fatigue.

METHODS

Cardiopulmonary exercise testing was used to assess cardiorespiratory fitness in a patient with end-stage PBC prior to listing for transplantation. A personalised exercise programme was designed to improve cardiorespiratory fitness while the patient was on the transplant waiting list.

RESULTS

Anaerobic threshold, VO_2PEAK and maximum workload all improved with regular exercise. Fatigue levels remained unaltered.

CONCLUSIONS

This patient tolerated and adhered to a personalised exercise programme for a prolonged period of time while awaiting surgery despite significant fatigue and disease burden. Liver transplantation was successfully completed and this woman remains well over 2 years post-surgery.

Sucrose ingestion after exhaustive exercise accelerates liver, but not muscle glycogen repletion compared with glucose ingestion in trained athletes

The purpose of this study was to assess the effects of sucrose vs. glucose ingestion on postexercise liver and muscle glycogen repletion. Fifteen well-trained male cyclists completed two test days. Each test day started with glycogen-depleting exercise, followed by 5 h of recovery, during which subjects ingested 1.5 g·kg(-1)·h(-1) sucrose or glucose. Blood was sampled frequently and (13)C magnetic resonance spectroscopy and imaging were employed 0, 120, and 300 min postexercise to determine liver and muscle glycogen concentrations and liver volume. Results were as follows: Postexercise muscle glycogen concentrations increased significantly from 85 ± 27 (SD) vs. 86 ± 35 mmol/l to 140 ± 23 vs. 136 ± 26 mmol/l following sucrose and glucose ingestion, respectively (no differences between treatments: P = 0.673). Postexercise liver glycogen concentrations increased significantly from 183 ± 47 vs. 167 ± 65 mmol/l to 280 ± 72 vs. 234 ± 81 mmol/l following sucrose and glucose ingestion, respectively (time × treatment, P = 0.051). Liver volume increased significantly over the 300-min period after sucrose ingestion only (time × treatment, P = 0.001). As a result, total liver glycogen content increased during postexercise recovery to a greater extent in the sucrose treatment (from 53.6 ± 16.2 to 86.8 ± 29.0 g) compared with the glucose treatment (49.3 ± 25.5 to 65.7 ± 27.1 g; time × treatment, P < 0.001), equating to a 3.4 g/h (95% confidence interval: 1.6-5.1 g/h) greater repletion rate with sucrose vs. glucose ingestion. In conclusion, sucrose ingestion (1.5 g·kg(-1)·h(-1)) further accelerates postexercise liver, but not muscle glycogen repletion compared with glucose ingestion in trained athletes.

Cross-sectional study of diet, physical activity, television viewing and sleep duration in 233,110 adults from the UK Biobank; the behavioural phenotype of cardiovascular disease and type 2 diabetes

OBJECTIVES

Simultaneously define diet, physical activity, television (TV) viewing, and sleep duration across cardiometabolic disease groups, and investigate clustering of non-diet lifestyle behaviours.

DESIGN

Cross-sectional observational study.

SETTING

22 UK Biobank assessment centres across the UK.

PARTICIPANTS

502,664 adults aged 37-63 years old, 54% women. 4 groups were defined based on disease status; 'No disease' (n=103,993), 'cardiovascular disease' (CVD n=113,469), 'Type 2 diabetes without CVD' (n=4074) and 'Type 2 diabetes + CVD' (n=11,574).

MAIN OUTCOMES

Diet, physical activity, TV viewing and sleep duration.

RESULTS

People with 'CVD' report low levels of physical activity (<918 MET min/week, OR (95% CI) 1.23 (1.20 to 1.25)), high levels of TV viewing (>3 h/day; 1.42 (1.39 to 1.45)), and poor sleep duration (<7, >8 h/night; 1.37 (1.34 to 1.39)) relative to people without disease. People with 'Type 2 diabetes + CVD' were more likely to report low physical activity (1.71 (1.64 to 1.78)), high levels of TV viewing (1.92 (1.85 to 1.99)) and poor sleep duration (1.52 (1.46 to 1.58)) relative to people without disease. Non-diet behaviours were clustered, with people with 'CVD' or 'Type 2 diabetes + CVD' more likely to report simultaneous low physical activity, high TV viewing and poor sleep duration than those without disease (2.15 (2.03 to 2.28) and 3.29 (3.02 to 3.58), respectively). By contrast, 3 in 4 adults with 'Type 2 diabetes', and 2 in 4 adults with 'CVD' have changed their diet in the past 5 years, compared with only 1 in 4 in the 'No disease' group. Models were adjusted for gender, age, body mass index, Townsend Deprivation Index, ethnicity, alcohol intake, smoking and meeting fruit/vegetable guidelines.

CONCLUSIONS

Low physical activity, high TV and poor sleep duration are prominent unaddressed high-risk characteristics of both CVD and type 2 diabetes, and are likely to be clustered together.

Targeting Lifestyle Behavior Change in Adults with NAFLD During a 20-min Consultation: Summary of the Dietary and Exercise Literature

Non-alcoholic fatty liver disease (NAFLD) is largely linked to poor diet, lack of physical activity/exercise, and being overweight. In the absence of approved pharmaceutical agents, lifestyle modification, encompassing dietary change and increased physical activity/exercise to initiate weight loss, is the recommended therapy for NAFLD. Despite this, the use of lifestyle therapy within clinical settings is lacking with limited guidance available about what it should involve, how it should be delivered, and whether it can be feasibly delivered as part of standard care. This paper highlights the evidence for the use of lifestyle modification in NAFLD. While there is evidence to support use of behavioral strategies to support lifestyle behavior change in other clinical populations, these are yet to be assessed in people with NAFLD. However, there is sufficient evidence to suggest that behavioral intervention targeting diet and physical activity to promote weight loss in general is effective and a number of practical strategies are presented on how this could be achieved.

Exercise Induces Peripheral Muscle But Not Cardiac Adaptations After Stroke: A Randomized Controlled Pilot Trial

Objective

To explore the physiological factors affecting exercise-induced changes in peak oxygen consumption and function poststroke.

Design

Single-center, single-blind, randomized controlled pilot trial.

Setting

Community stroke services.

Participants

Adults (N=40; age>50y; independent with/without stick) with stroke (diagnosed >6mo previously) were recruited from 117 eligible participants. Twenty participants were randomized to the intervention group and 20 to the control group. No dropouts or adverse events were reported.

Interventions

Intervention group: 19-week (3times/wk) progressive mixed (aerobic/strength/balance/flexibility) community group exercise program. Control group: Matched duration home stretching program.

Main Outcome Measures

(1) Pre- and postintervention: maximal cardiopulmonary exercise testing with noninvasive (bioreactance) cardiac output measurements; and (2) functional outcome measures: 6-minute walk test; timed Up and Go test, and Berg Balance Scale.

Results

Exercise improved peak oxygen consumption (18±5 to 21±5mL/(kg⋅min); P<.01) and peak arterial-venous oxygen difference (9.2±2.7 to 11.4±2.9mL of O₂/100mL of blood; P<.01), but did not alter cardiac output (17.2±4 to 17.7±4.2L/min; P=.44) or cardiac power output (4.8±1.3 to 5.0±1.35W; P=.45). A significant relation existed between change in peak oxygen consumption and change in peak arterial-venous oxygen difference (r=.507; P<.05), but not with cardiac output. Change in peak oxygen consumption did not strongly correlate with change in function.

Conclusions

Exercise induced peripheral muscle, but not cardiac output, adaptations after stroke. Implications for stroke clinical care should be explored further in a broader cohort.

High intensity intermittent exercise improves cardiac structure and function and reduces liver fat in patients with type 2 diabetes: a randomised controlled trial

AIMS/HYPOTHESIS

Cardiac disease remains the leading cause of mortality in type 2 diabetes, yet few strategies to target cardiac dysfunction have been developed. This randomised controlled trial aimed to investigate high intensity intermittent training (HIIT) as a potential therapy to improve cardiac structure and function in type 2 diabetes. The impact of HIIT on liver fat and metabolic control was also investigated.

METHODS

Using an online random allocation sequence, 28 patients with type 2 diabetes (metformin and diet controlled) were randomised to 12 weeks of HIIT (n = 14) or standard care (n = 14). Cardiac structure and function were measured by 3.0 T MRI and tagging. Liver fat was determined by 1H-magnetic resonance spectroscopy and glucose control by an OGTT. MRI analysis was performed by an observer blinded to group allocation. All study procedures took place in Newcastle upon Tyne, UK.

RESULTS

Five patients did not complete the study and were therefore excluded from analysis: this left 12 HIIT and 11 control patients for the intention-to-treat analysis. Compared with controls, HIIT improved cardiac structure (left ventricular wall mass 104 ± 17 g to 116 ± 20 g vs. 107 ± 25 g to 105 ± 25 g, p < 0.05) and systolic function (stroke volume 76 ± 16 ml to 87 ± 19 ml vs. 79 ± 14 ml to 75 ± 15 ml, p < 0.01). Early diastolic filling rates increased (241 ± 84 ml/s to 299 ± 89 ml/s vs. 250 ± 44 ml/s to 251 ± 47 ml/s, p < 0.05) and peak torsion decreased (8.1 ± 1.8° to 6.9 ± 1.6° vs. 7.1 ± 2.2° to 7.6 ± 1.9°, p < 0.05) in the treatment group. Following HIIT, there was a 39% relative reduction in liver fat (p < 0.05) and a reduction in HbA1c (7.1 ± 1.0% [54.5 mmol/mol] to 6.8 ± 0.9% [51.3 mmol/mol] vs. 7.2 ± 0.5% [54.9 mmol/mol] to 7.4 ± 0.7% [57.0 mmol/mol], p < 0.05). Changes in liver fat correlated with changes in HbA1c (r = 0.70, p < 0.000) and 2 h glucose (r = 0.57, p < 0.004). No adverse events were recorded.

CONCLUSIONS/INTERPRETATION

This is the first study to demonstrate improvements in cardiac structure and function, along with the greatest reduction in liver fat, to be recorded following an exercise intervention in type 2 diabetes. HIIT should be considered by clinical care teams as a therapy to improve cardiometabolic risk in patients with type 2 diabetes.

TRIAL REGISTRATION

www.isrctn.com 78698481 FUNDING: : Medical Research Council.

Ingestion of glucose or sucrose prevents liver but not muscle glycogen depletion during prolonged endurance-type exercise in trained cyclists

The purpose of this study was to define the effect of glucose ingestion compared with sucrose ingestion on liver and muscle glycogen depletion during prolonged endurance-type exercise. Fourteen cyclists completed two 3-h bouts of cycling at 50% of peak power output while ingesting either glucose or sucrose at a rate of 1.7 g/min (102 g/h). Four cyclists performed an additional third test for reference in which only water was consumed. We employed (13)C magnetic resonance spectroscopy to determine liver and muscle glycogen concentrations before and after exercise. Expired breath was sampled during exercise to estimate whole body substrate use. After glucose and sucrose ingestion, liver glycogen levels did not show a significant decline after exercise (from 325 ± 168 to 345 ± 205 and 321 ± 177 to 348 ± 170 mmol/l, respectively; P > 0.05), with no differences between treatments. Muscle glycogen concentrations declined (from 101 ± 49 to 60 ± 34 and 114 ± 48 to 67 ± 34 mmol/l, respectively; P < 0.05), with no differences between treatments. Whole body carbohydrate utilization was greater with sucrose (2.03 ± 0.43 g/min) vs. glucose (1.66 ± 0.36 g/min; P < 0.05) ingestion. Both liver (from 454 ± 33 to 283 ± 82 mmol/l; P < 0.05) and muscle (from 111 ± 46 to 67 ± 31 mmol/l; P < 0.01) glycogen concentrations declined during exercise when only water was ingested. Both glucose and sucrose ingestion prevent liver glycogen depletion during prolonged endurance-type exercise. Sucrose ingestion does not preserve liver glycogen concentrations more than glucose ingestion. However, sucrose ingestion does increase whole body carbohydrate utilization compared with glucose ingestion. This trial was registered at https://www.clinicaltrials.gov as NCT02110836.

A Novel, Open Access Method to Assess Sleep Duration Using a Wrist-Worn Accelerometer

Wrist-worn accelerometers are increasingly being used for the assessment of physical activity in population studies, but little is known about their value for sleep assessment. We developed a novel method of assessing sleep duration using data from 4,094 Whitehall II Study (United Kingdom, 2012-2013) participants aged 60-83 who wore the accelerometer for 9 consecutive days, filled in a sleep log and reported sleep duration via questionnaire. Our sleep detection algorithm defined (nocturnal) sleep as a period of sustained inactivity, itself detected as the absence of change in arm angle greater than 5 degrees for 5 minutes or more, during a period recorded as sleep by the participant in their sleep log. The resulting estimate of sleep duration had a moderate (but similar to previous findings) agreement with questionnaire based measures for time in bed, defined as the difference between sleep onset and waking time (kappa = 0.32, 95%CI:0.29,0.34) and total sleep duration (kappa = 0.39, 0.36,0.42). This estimate was lower for time in bed for women, depressed participants, those reporting more insomnia symptoms, and on weekend days. No such group differences were found for total sleep duration. Our algorithm was validated against data from a polysomnography study on 28 persons which found a longer time window and lower angle threshold to have better sensitivity to wakefulness, while the reverse was true for sensitivity to sleep. The novelty of our method is the use of a generic algorithm that will allow comparison between studies rather than a "count" based, device specific method.

The effect of age on the relationship between cardiac and vascular function

Age-related changes in cardiac and vascular function are associated with increased risk of cardiovascular mortality and morbidity. The aim of the present study was to define the effect of age on the relationship between cardiac and vascular function. Haemodynamic and gas exchange measurements were performed at rest and peak exercise in healthy individuals. Augmentation index was measured at rest. Cardiac power output, a measure of overall cardiac function, was calculated as the product of cardiac output and mean arterial blood pressure. Augmentation index was significantly higher in older than younger participants (27.7 ± 10.1 vs. 2.5 ± 10.1%, P<0.01). Older people demonstrated significantly higher stroke volume and mean arterial blood pressure (P<0.05), but lower heart rate (145 ± 13 vs. 172 ± 10 beats/min, P<0.01) and peak oxygen consumption (22.5 ± 5.2 vs. 41.2 ± 8.4 ml/kg/min, P<0.01). There was a significant negative relationship between augmentation index and peak exercise cardiac power output (r=-0.73, P=0.02) and cardiac output (r=-0.69, P=0.03) in older participants. Older people maintain maximal cardiac function due to increased stroke volume. Vascular function is a strong predictor of overall cardiac function in older but in not younger people.

Successful behavioural strategies to increase physical activity and improve glucose control in adults with Type 2 diabetes

AIMS

To explore which behaviour change techniques and other intervention features are associated with increased levels of physical activity and improved HbA1c in adults with Type 2 diabetes.

METHODS

Moderator analyses were performed on a dataset of 21 behaviour change techniques and six intervention features identified in a systematic review of behavioural interventions (N = 1975 patients with Type 2 diabetes) to establish their associations with changes in physical activity and HbA1c .

RESULTS

Four behaviour change techniques (prompt focus on past success, barrier identification/problem-solving, use of follow-up prompts and provide information on where and when to perform physical activity) had statistically significant associations with increased levels of physical activity. Prompt review of behavioural goals and provide information on where and when to perform physical activity behaviour had statistically significant associations with improved HbA1c . Pedometer use was associated with decreased levels of physical activity.

CONCLUSIONS

These data suggest that clinical care teams can optimise their consultations by incorporating specific behaviour change techniques that are associated with increased levels of physical activity and improved long-term glycaemic control.

Preliminary Evaluation of Clinician Rated Outcome Measures in Mitochondrial Disease

BACKGROUND

Currently there are no known cures and few effective treatments for mitochondrial disorders. It is also true there is a lack of knowledge about suitable clinician rated outcomes and how these change over time in this patient cohort.

OBJECTIVE

We sought to evaluate the validity and responsiveness to change of clinician rated outcome measures in patients with m.3243A>G-related mitochondrial disease.

METHODS

We assessed the six minute timed walk (6MTW), 10 meter walk / test (10MWT), Timed up and Go (TUG) and the 5 times sit to stand (5XSTS), in 18 patients (12 sedentary controls), at baseline and a subgroup of 10 control-matched patients following a 16-week structured aerobic exercise intervention program.

RESULTS

All outcome measures assessed were valid and able to differentiate between patients and controls. Disease severity, as measured by the Newcastle Mitochondrial Disease Adult Scale, correlated with TUG (r = 0.54, p = 0.020) and 10MWT (r = 0.47, p = 0.050). Receiver Operating Curve analysis revealed 5XSTS to be the most responsive measure (AUC 0.931; 95% CI 0.84- 1.00) with responsiveness to change, post intervention, emulating disease burden variance.

CONCLUSIONS

The 5XSTS can be used to discriminate between mitochondrial patients and sedentary controls with high accuracy. The 10MWT and TUG may serve as suitable and clinically relevant clinician rated measures to track disease progression and assess intervention.

Cardiac structure and function are altered in type 2 diabetes and non-alcoholic fatty liver disease and associate with glycemic control

BACKGROUND

Both non-alcoholic fatty liver disease (NAFLD) and Type 2 diabetes increase the risk of developing cardiovascular disease. The metabolic processes underlying NAFLD and Type 2 diabetes are part of an integrated mechanism but little is known about how these conditions may differentially affect the heart. We compared the impact of NAFLD and Type 2 diabetes on cardiac structure, function and metabolism.

METHODS

19 adults with Type 2 diabetes (62 ± 8 years), 19 adults with NAFLD (54 ± 15 years) and 19 healthy controls (56 ± 14 years) underwent assessment of cardiac structure, function and metabolism using high resolution magnetic resonance imaging, tagging and spectroscopy at 3.0 T.

RESULTS

Adults with NAFLD and Type 2 diabetes demonstrate concentric remodelling with an elevated eccentricity ratio compared to controls (1.05 ± 0.3 vs. 1.12 ± 0.2 vs. 0.89 ± 0.2 g/ml; p < 0.05). Despite this, only the Type 2 diabetes group demonstrate significant systolic and diastolic dysfunction evidenced by a reduced stroke index (31 ± 7vs. controls, 38 ± 10, p < 0.05 ml/m2) and reduced E/A (0.9 ± 0.4 vs. controls, 1.9 ± 1.4, p < 0.05) respectively. The torsion to shortening ratio was higher in Type 2 diabetes compared to NAFLD (0.58 ± 0.16 vs. 0.44 ± 0.13; p < 0.05). Significant associations were observed between fasting blood glucose/HbA1c and diastolic parameters as well as the torsion to shortening ratio (all p < 0.05). Phosphocreatine/adenosine triphosphate ratio was not altered in NAFLD or Type 2 diabetes compared to controls.

CONCLUSIONS

Changes in cardiac structure are evident in adults with Type 2 diabetes and NAFLD without overt cardiac disease and without changes in cardiac energy metabolism. Only the Type 2 diabetes group display diastolic and subendocardial dysfunction and glycemic control may be a key mediator of these cardiac changes. Therapies should be explored to target these preclinical cardiac changes to modify cardiovascular risk associated with Type 2 diabetes and NAFLD.

Non-alcoholic fatty liver disease is associated with higher levels of objectively measured sedentary behaviour and lower levels of physical activity than matched healthy controls

BACKGROUND AND AIMS

Physical activity is a key determinant of metabolic control and is recommended for people with non-alcoholic fatty liver disease (NAFLD), usually alongside weight loss and dietary change. To date, no studies have reported the relationship between objectively measured sedentary behaviour and physical activity, liver fat and metabolic control in people with NAFLD, limiting the potential to target sedentary behaviour in clinical practice. This study determined the level of sedentary behaviour and physical activity in people with NAFLD, and investigated links between physical activity, liver fat and glucose control.

METHODS

Sedentary behaviour, physical activity and energy expenditure were assessed in 37 adults with NAFLD using a validated multisensor array over 7 days. Liver fat and glucose control were assessed, respectively, by ¹H-MRS and fasting blood samples. Patterns of sedentary behaviour were assessed by power law analyses of the lengths of sedentary bouts fitted from raw sedentary data. An age and sex-matched healthy control group wore the activity monitor for the same time period.

RESULTS

People with NAFLD spent approximately half an hour extra a day being sedentary (1318±68 vs1289±60 mins/day; p<0.05) and walked 18% fewer steps (8483±2926 vs 10377±3529 steps/day; p<0.01). As a consequence, active energy expenditure was reduced by 40% (432±258 vs 732±345 kcal/day; p<0.01) and total energy expenditure was lower in NAFLD (2690±440 vs 2901±511 kcal/day; p<0.01). Power law analyses of the lengths of sedentary bouts demonstrated that patients with NAFLD also have a lower number of transitions from being sedentary to active compared with controls (13±0.03 vs15±0.03%; p<0.05).

CONCLUSIONS

People with NAFLD spend more time sedentary and undertake less physical activity on a daily basis than healthy controls. High levels of sedentary behaviour and low levels of physical activity represent a therapeutic target that may prevent progression of metabolic conditions and weight gain in people with NAFLD and should be considered in clinical care.

Effect of physical activity on age-related changes in cardiac function and performance in women

BACKGROUND

Higher levels of physical activity are associated with reduced cardiovascular mortality but its effect on age-related changes in cardiac structure and function is unknown. The present study defines the effect of daily physical activity on age-related changes in cardiac structure, function, metabolism, and performance in healthy women.

METHODS AND RESULTS

Sixty-three healthy women were grouped according to age (young, 20-30 years, n=21; middle, 40-50 years, n=22; and older, 65-81 years, n=20) and daily physical activity level (low active<7500 and high active>12,500 steps/d). Participants underwent cardiac MRI including tissue tagging and 31P spectroscopy and exercise testing with noninvasive central hemodynamic measurements. Aging was associated with increased concentric remodeling (P<0.01) and left ventricular torsion (P<0.01), and a decline in diastolic function (P<0.01), cardiac phosphocreatine:ATP ratio (P<0.01), peak exercise cardiac power output (P<0.01), and O2 consumption (P<0.01). Older high-active women demonstrated a phosphocreatine:ATP ratio and relative peak O2 consumption similar to young low-active women, and 23% and 26% higher than older low-active women (phosphocreatine:ATP ratio, 1.9±0.2 versus 1.4±0.1; P<0.05 and O2 consumption, 24.1±3.8 versus 17.8±2.0 mL/[kg·min]; P<0.01). In older women, physical activity had no effect on eccentricity ratio (0.9±0.2 versus 0.8±0.1 g/mL; P=0.19), E/A ratio (1.3±0.5 versus 1.4±0.5; P=0.66), torsion (7.6±1.7 versus 8.0°±2.1°; P=0.20), and peak cardiac power output (3.4±0.7 versus 3.4±0.8 W; P=0.91).

CONCLUSIONS

A higher level of daily physical activity preserves cardiac metabolism and exercise capacity with aging but has limited effect on age-related changes in concentric remodeling, diastolic function, and cardiac performance.

Effects of Community Exercise Therapy on Metabolic, Brain, Physical, and Cognitive Function Following Stroke

Background. Exercise therapy could potentially modify metabolic risk factors and brain physiology alongside improving function post stroke. Objective. To explore the short-term metabolic, brain, cognitive, and functional effects of exercise following stroke. Methods. A total of 40 participants (>50 years, >6 months post stroke, independently mobile) were recruited to a single-blind, parallel, randomized controlled trial of community-based exercise (19 weeks, 3 times/wk, “exercise” group) or stretching (“control” group). Primary outcome measures were glucose control and cerebral blood flow. Secondary outcome measures were cardiorespiratory fitness, blood pressure, lipid profile, body composition, cerebral tissue atrophy and regional brain metabolism, and physical and cognitive function. Results. Exercise did not change glucose control (homeostasis model assessment 1·5 ± 0·8 to 1·5 ± 0·7 vs 1·6 ± 0·8 to 1·7 ± 0·7, P = .97; CI = −0·5 to 0·49). Medial temporal lobe tissue blood flow increased with exercise (38 ± 8 to 42 ± 10 mL/100 g/min; P < .05; CI = 9.0 to 0.1) without any change in gray matter tissue volume. There was no change in medial temporal lobe tissue blood flow in the control group (41 ± 8 to 40 ± 7 mL/100 g/min; P = .13; CI = −3.6 to 6.7) but significant gray matter atrophy. Cardiorespiratory fitness, diastolic blood pressure, high-density lipoprotein cholesterol, physical function, and cognition also improved with exercise. Conclusion. Exercise therapy improves short-term metabolic, brain, physical, and cognitive function, without changes in glucose control following stroke. The long-term impact of exercise on stroke recurrence, cardiovascular health, and disability should now be explored.

Autocalibration of accelerometer data for free-living physical activity assessment using local gravity and temperature: an evaluation on four continents

Wearable acceleration sensors are increasingly used for the assessment of free-living physical activity. Acceleration sensor calibration is a potential source of error. This study aims to describe and evaluate an autocalibration method to minimize calibration error using segments within the free-living records (no extra experiments needed). The autocalibration method entailed the extraction of nonmovement periods in the data, for which the measured vector magnitude should ideally be the gravitational acceleration (1 g); this property was used to derive calibration correction factors using an iterative closest-point fitting process. The reduction in calibration error was evaluated in data from four cohorts: UK (n = 921), Kuwait (n = 120), Cameroon (n = 311), and Brazil (n = 200). Our method significantly reduced calibration error in all cohorts (P < 0.01), ranging from 16.6 to 3.0 mg in the Kuwaiti cohort to 76.7 to 8.0 mg error in the Brazil cohort. Utilizing temperature sensor data resulted in a small nonsignificant additional improvement (P > 0.05). Temperature correction coefficients were highest for the z-axis, e.g., 19.6-mg offset per 5°C. Further, application of the autocalibration method had a significant impact on typical metrics used for describing human physical activity, e.g., in Brazil average wrist acceleration was 0.2 to 51% lower than uncalibrated values depending on metric selection (P < 0.01). The autocalibration method as presented helps reduce the calibration error in wearable acceleration sensor data and improves comparability of physical activity measures across study locations. Temperature ultization seems essential when temperature deviates substantially from the average temperature in the record but not for multiday summary measures.

A low-glycemic index meal and bedtime snack prevents postprandial hyperglycemia and associated rises in inflammatory markers, providing protection from early but not late nocturnal hypoglycemia following evening exercise in type 1 diabetes

OBJECTIVE

To examine the influence of the glycemic index (GI) of foods consumed after evening exercise on postprandial glycemia, metabolic and inflammatory markers, and nocturnal glycemic control in type 1 diabetes.

RESEARCH DESIGN AND METHODS

On two evenings (∼1700 h), 10 male patients (27 ± 5 years of age, HbA1c 6.7 ± 0.7% [49.9 ± 8.1 mmol/mol]) were administered a 25% rapid-acting insulin dose with a carbohydrate bolus 60 min before 45 min of treadmill running. At 60 min postexercise, patients were administered a 50% rapid-acting insulin dose with one of two isoenergetic meals (1.0 g carbohdyrate/kg body mass [BM]) matched for macronutrient content but of either low GI (LGI) or high GI (HGI). At 180 min postmeal, the LGI group ingested an LGI snack and the HGI group an HGI snack (0.4 g carbohdyrate/kg BM) before returning home (∼2300 h). Interval samples were analyzed for blood glucose and lactate; plasma glucagon, epinephrine, interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α); and serum insulin, cortisol, nonesterified fatty acid, and β-hydroxybutyrate concentrations. Interstitial glucose was recorded for 20 h postlaboratory attendance through continuous glucose monitoring.

RESULTS

Following the postexercise meal, an HGI snack induced hyperglycemia in all patients (mean ± SD glucose 13.5 ± 3.3 mmol/L) and marked increases in TNF-α and IL-6, whereas relative euglycemia was maintained with an LGI snack (7.7 ± 2.5 mmol/L, P < 0.001) without inflammatory cytokine elevation. Both meal types protected all patients from early hypoglycemia. Overnight glycemia was comparable, with a similar incidence of nocturnal hypoglycemia (n = 5 for both HGI and LGI).

CONCLUSIONS

Consuming LGI food with a reduced rapid-acting insulin dose following evening exercise prevents postprandial hyperglycemia and inflammation and provides hypoglycemia protection for ∼8 h postexercise; however, the risk of late nocturnal hypoglycemia remains.

Effect of left ventricular assist device implantation and heart transplantation on habitual physical activity and quality of life

The present study defined the short- and long-term effects of left ventricular assist device (LVAD) implantation and heart transplantation (HT) on physical activity and quality of life (QoL). Forty patients (LVAD, n = 14; HT, n = 12; and heart failure [HF], n = 14) and 14 matched healthy subjects were assessed for physical activity, energy expenditure, and QoL. The LVAD and HT groups were assessed postoperatively at 4 to 6 weeks (baseline) and 3, 6, and 12 months. At baseline, LVAD, HT, and HF patients demonstrated low physical activity, reaching only 15%, 28%, and 51% of that of healthy subjects (1,603 ± 302 vs 3,036 ± 439 vs 5,490 ± 1,058 vs 10,756 ± 568 steps/day, respectively, p <0.01). This was associated with reduced energy expenditure and increased sedentary time (p <0.01). Baseline QoL was not different among LVAD, HT, and HF groups (p = 0.44). LVAD implantation and HT significantly increased daily physical activity by 60% and 52%, respectively, from baseline to 3 months (p <0.05), but the level of activity remained unchanged at 3, 6, and 12 months. The QoL improved from baseline to 3 months in LVAD implantation and HT groups (p <0.01) but remained unchanged afterward. At any time point, HT demonstrated higher activity level than LVAD implantation (p <0.05), and this was associated with better QoL. In contrast, physical activity and QoL decreased at 12 months in patients with HF (p <0.05). In conclusion, patients in LVAD and HT patients demonstrate improved physical activity and QoL within the first 3 months after surgery, but physical activity and QoL remain unchanged afterward and well below that of healthy subjects. Strategies targeting low levels of physical activity should now be explored to improve recovery of these patients.