Comprehensive Study of Heart Rate Recovery and Altered Ventilatory Response to Exercise in Patients with Obstructive Sleep Apnea

Background Obstructive sleep apnea (OSA) is a chronic disorder that results in many cardiovascular disorders including hypertension, arrhythmias and congestive heart failure (CHF). Polysomnography is the gold standard for diagnosis of OSA, even though up to 93% of women and 82% of men with moderate to severe OSA still remain undiagnosed. Cardiopulmonary exercise testing (CPXT) has been conventionally used for evaluation of coronary artery diseases and rehabilitation of cardiac patients. Modern systems allow for the analysis of gas exchange at rest, during exercise, and during recovery and also yield measures of oxygen uptake (V O2), carbon dioxide output (V CO2), and minute ventilation (V E) together with heart rate, blood pressure, electrocardiography findings, and symptoms. This may have clinical utility if added to the available screening tools used to identify OSA. Aim of study To assess altered ventilatory response and heart rate recovery in response to exercise in patients with obstructive sleep apnea and their relation to its severity. Methods and Results Case control study was enrolled including 30 patients with obstructive sleep apnea (OSA) divided according to severity (5 mild, 8 moderate and 17 severe) and 15 control healthy overweight with sedentary lifestyle individuals. The two groups underwent cardiopulmonary exercise testing and different pulmonary and cardiac parameters were calculated. Greater VE, VE/VCO2, VE/VO2 ratios and VE/VCO2 slope were statistically significant regarding the patients group (P < 0.001, F = 69.053, 104.381, 140.806 and 68.010 respectively according to ANOVA test). OSA patients had a reduced maximal exercise capacity expressed as lower VO2 peak, decreased breathing reserve (BR) and VO2 at anaerobic threshold compared to control group (P < 0.001, F = 22.597, 68.773 and 82.90 respectively). Delayed heart rate recovery (HRR) and weaker chronotropic response (CR) in patients with OSA than in controls with negative relationship to severity of OSA were proved (p < 0.001, F = 119.493 and 91.271 respectively). The study revealed elevated maximal systolic BP (max SBP), diastolic BP (max DBP) and recovery SBP in the following 2 minutes after exercise in patients with OSA relative to their healthy controls with positive relationship to the severity of OSA (P < 0.001, F = 37.129, 169.275 and 244.609 respectively). Conclusion Patients with OSA demonstrated exaggerated ventilatory response to exercise and autonomic dysfunction reflected by measurement of heart rate variability and reduced maximal exercise capacity than healthy controls. Abbreviations OSA, CHF, CPXT, VO2, VCO2, VE, VE/VCO2, VE/VO2, VE/VCO2, BR, CR, HRR, max SBP and max DBP.

Cardiovascular risk associated with long-term anabolic-androgenic steroid abuse: an observational study from Norway

Background The use of anabolic-androgenic steroids (AAS) has become highly prevalent among recreational weightlifters. Numerous case reports have suggested an association between AAS use and a vast range of different cardiovascular diseases, including sudden cardiac death (SCD) and coronary artery disease (CAD). Few clinical studies have evaluated the risk of SCD and the prevalence of CAD in individuals with long-term AAS use. Purpose To evaluate the risk of ventricular arrhythmias and the prevalence of CAD among men with long-term AAS use. Methods Strength-trained men with at least three years of cumulative AAS use were recruited from recreational gyms. The control group consisted of strength-trained competing athletes who self-reported never using any performance enhancing drugs (non-users). AAS use was verified by sophisticated blood and urine analyses. Study participants went through a comprehensive cardiovascular evaluation including exercise ECG, 24 h ECG, heart rate variability (HRV) measures, signal averaged ECG (SAECG) and QT dispersion (QTd). Coronary computed tomography angiography (CCTA) was performed in AAS users. Not all participants had all tests. Results We included 51 AAS users and 21 non-users. Median age (25th-75th percentile) was 33 (29–37) years in the user group and 33 (29–42) years in the non-user group. Forty-eight (94%) of the users had been using AAS for five years or more. Characteristics are presented in the table. AAS users had significantly lower HDL values compared to non-users (p<0.001). No signs of ischemia or arrhythmias were detected during exercise ECG, however maximal exercise capacity was lower than in the control group and also compared to age-standardized values. A considerable, but statistically non-significant reduction was seen in overall HRV estimated as the standard deviation of the RR intervals for normal sinus beats (SDNN) (p=0.05). No difference was seen regarding left ventricular late potentials or QTd (table). Eight (19%) of the forty-two AAS users undergoing CCTA had at least a mild degree of CAD, and four of them three-vessel disease. Conclusion No ECG-findings indicated an increased risk of ventricular arrhythmias among the long-term AAS users. However, their maximal exercise capacity was lower than in controls, and one fifth of the long-term AAS users had verified CAD on CT coronary angiography. FUNDunding Acknowledgement Type of funding sources: None. Table 1

Study protocol for a randomised controlled trial assessing the impact of pulmonary rehabilitation on maximal exercise capacity for adults living with post-TB lung disease: Global RECHARGE Uganda

IntroductionThe burden of post-tuberculosis (TB) lung disease (PTBLD) is steadily increasing in sub-Saharan Africa, causing disability among TB survivors. Without effective medicines, the mainstay of PTBLD treatment evolves around disease prevention and supportive treatment. Pulmonary rehabilitation (PR), a low-cost, non-pharmacological intervention has shown effectiveness in a group of PTBLD individuals but has not been tested in a clinical trial. This study aims to assess the impact of a 6-week PR programme on maximal exercise capacity and other outcomes among adults in Uganda living with PTBLD.Methods and analysisThis is a randomised waiting-list controlled trial with blinded outcome measures, comparing PR versus usual care for patients with PTBLD. A total of 114 participants will be randomised (1:1) to receive either usual care (on the waiting list) or PR, with follow-up assessments at 6 weeks and 12 weeks postintervention. The primary outcome is change in walking distance measured by the Incremental Shuttle Walk Test from baseline to the end of 6 weeks of PR. All secondary outcomes will be compared between the PR and usual care arms from baseline to 6-week and 12-week follow-ups. Secondary outcomes include self-reported respiratory symptoms, physical activity, psychological well-being, health-related quality of life and cost–benefit analysis. All randomised participants will be included in the intention-to-treat analysis population. The primary efficacy analysis will be based on both per-protocol and modified intention-to-treat populations.Ethics and disseminationThe trial has received ethical clearance from the Mulago Hospital Research and Ethics Committee (MHREC 1478), Kampala, Uganda as well as the Uganda National Council for Science and Technology (SS 5105). Ethical approval has been obtained from the University of Leicester, UK research ethics committee (Ref No. 22349). Study findings will be published in appropriate peer-reviewed journals and disseminated at appropriate local, regional and international scientific meetings and conferences.Trial registration numberISRCTN18256843.Protocol versionVersion 1.0 July 2019.

Effects of acute exercise on spontaneous physical activity in mice at different ages

Background Exercise is often used to obtain a negative energy balance. However, its effects on body weight reduction are usually below expectations. One possible explanation is a reduction in spontaneous physical activity (SPA) after exercise since the increase in energy expenditure caused by the exercise session would be offset by the decrease in SPA and its associated energy cost. Thus, we evaluated the effects of a single bout of moderate exercise at individualized intensity on spontaneous physical activity. The impact of the single bout of exercise was determined in early adulthood and at the transition to middle age. Methods Male C57bl/6j (n = 10) mice were evaluated at 4 (4 M) and 9 (9 M) months of age. One week after a treadmill Maximal Exercise Capacity Test (MECT), mice performed a 30-min single bout of exercise at 50 % of the maximal speed reached at MECT. An infrared-based system was used to determine locomotor parameters (SPA and average speed of displacement, ASD) before (basal) and immediately after the single bout of exercise for 48 h (D1, 0-24 h; D2, 24-48 h). Food intake was measured simultaneously. Data were analyzed by GEE and statistical significance was set at p < 0.05. Results Basal SPA declined from 4 M to 9 M (p = 0.01), but maximal exercise capacity was similar. At both ages, SPA and ASD decreased significantly (p < 0.0001) on day 1 after exercise. On D2, SPA returned to basal levels but ASD remained lower than basal (p < 0.001). The magnitude (% of basal) of change in SPA and ASD on D1 and D2 was similar at 4 M and 9 M. Food intake did not change at 4 M but decreased on D2 at 9 M. Conclusions A single bout of moderate exercise decreases physical activity in the first 24 h and average speed of locomotion in the 48 h following exercise. This compensation is similar from early adulthood to the transition to middle age. The decrease in both the amount and intensity (speed) of SPA may compensate for the increase in energy expenditure induced by exercise, helping to understand the below-than-expected effect of exercise interventions to cause a negative energy balance.

A Low-Carbohydrate Ketogenic Diet and Treadmill Training Enhanced Fatty Acid Oxidation Capacity but Did Not Enhance Maximal Exercise Capacity in Mice

The low-carbohydrate ketogenic diet (LCKD) is a dietary approach characterized by the intake of high amounts of fat, a balanced amount of protein, and low carbohydrates, which is insufficient for metabolic demands. Previous studies have shown that an LCKD alone may contribute to fatty acid oxidation capacity, along with endurance. In the present study, we combined a 10-week LCKD with an 8-week forced treadmill running program to determine whether training in conjunction with LCKD enhanced fatty acid oxidation capacity, as well as whether the maximal exercise capacity would be affected by an LCKD or training in a mice model. We found that the lipid pool and fatty acid oxidation capacity were both enhanced following the 10-week LCKD. Further, key fatty acid oxidation related genes were upregulated. In contrast, the 8-week training regimen had no effect on fatty acid and ketone body oxidation. Key genes involved in carbohydrate utilization were downregulated in the LCKD groups. However, the improved fatty acid oxidation capacity did not translate into an enhanced maximal exercise capacity. In summary, while favoring the fatty acid oxidation system, an LCKD, alone or combined with training, had no beneficial effects in our intensive exercise-evaluation model. Therefore, an LCKD may be promising to improve endurance in low- to moderate-intensity exercise, and may not be an optimal choice for those partaking in high-intensity exercise.