Duration Of Exercise Training Research Articles

Energy Requirements of Paralympic Athletes: Insights from the Doubly Labeled Water Approach.

Advanced insight in energy requirements of Paralympic athletes is imperative for optimizing their nutritional counseling. Given the lack of accurate data on total daily energy expenditure (TDEE) of Paralympic athletes, this study aimed to assess energy expenditure and nutritional intake of a large cohort of Paralympic athletes, across different sports and disabilities. In this cross-sectional study, 48 Dutch and Norwegian Paralympic athletes (19 male/29 female) with various disabilities, competing in Para cycling, wheelchair tennis, wheelchair basketball, Para Nordic skiing, and alpine skiing participated. TDEE was assessed by the gold standard doubly labeled water method over a 14-d period, resting metabolic rate by ventilated hood indirect calorimetry, energy intake by three unannounced 24-h dietary recalls, body composition by dual-energy x-ray absorptiometry, and exercise training duration by a training log. Mean TDEE was 2908 ± 797 kcal·d -1 , ranging from 2322 ± 340 kcal·d -1 for wheelchair basketball players to 3607 ± 1001 kcal·d -1 for Para cyclists. Regression analysis identified fat-free mass, exercise duration, and the presence of a spinal cord disorder as the primary predictors of TDEE, explaining up to 73% of the variance in TDEE. Athletes' energy intake (2363 ± 905 kcal·d -1 ) was below their TDEE, whereas their body mass remained constant, indicating underreporting. Carbohydrate intake (4.1 ± 1.9 g·kg -1 body mass) was low, even when considering underreporting, whereas protein intake (1.8 ± 0.6 g·kg -1 body mass) was relatively high. Paralympic athletes display moderate- to high-energy expenditure, varying across sports and individuals. Much of the variation in TDEE can be attributed to individual differences in fat-free mass and exercise duration. This study establishes the benchmarks for energy requirements of Paralympic athletes, serving as the foundation for future dietary guidelines within this population.

Exposures to Elevated Core Temperatures during Football Training: The Impact on Autonomic Nervous System Recovery and Function.

Exercising with elevated core temperatures may negatively affect autonomic nervous system (ANS) function. Additionally, longer training duration under higher core temperatures may augment these negative effects. This study evaluated the relationship between exercise training duration and 24 h ANS recovery and function at ≥37 °C, ≥38 °C and ≥39 °C core temperature thresholds in a sample of male Division I (D1) collegiate American football athletes. Fifty athletes were followed over their 25-week season. Using armband monitors (Warfighter MonitorTM, Tiger Tech Solutions, Inc., Miami, FL, USA), core temperature (°C) and 24 h post-exercise baseline heart rate (HR), HR recovery and heart rate variability (HRV) were measured. For HRV, two time-domain indices were measured: the root mean square of the standard deviation of the NN interval (rMSSD) and the standard deviation of the NN interval (SDNN). Linear regression models were performed to evaluate the associations between exercise training duration and ANS recovery (baseline HR and HRV) and function (HR recovery) at ≥37 °C, ≥38 °C and ≥39 °C core temperature thresholds. On average, the athletes were 21.3 (± 1.4) years old, weighed 103.0 (±20.2) kg and had a body fat percentage of 15.4% (±7.8%, 3.0% to 36.0%). The duration of training sessions was, on average, 161.1 (±40.6) min and they ranged from 90.1 to 339.6 min. Statistically significant associations between training duration and 24 h ANS recovery and function were observed at both the ≥38.0 °C (baseline HR: β = 0.10 ± 0.02, R2 = 0.26, p < 0.0000; HR recovery: β = -0.06 ± 0.02, R2 = 0.21, p = 0.0002; rMSSD: β = -0.11 ± 0.02, R2 = 0.24, p < 0.0000; and SDNN: β = -0.16 ± 0.04, R2 = 0.22, p < 0.0000) and ≥39.0 °C thresholds (β = 0.39 ± 0.05, R2 = 0.62, p < 0.0000; HR recovery: β = -0.26 ± 0.04, R2 = 0.52, p < 0.0000; rMSSD: β = -0.37 ± 0.05, R2 = 0.58, p < 0.0000; and SDNN: β = -0.67 ± 0.09, R2 = 0.59, p < 0.0000). With increasing core temperatures, increases in slope steepness and strengths of the associations were observed, indicating accelerated ANS deterioration. These findings demonstrate that exercise training under elevated core temperatures (≥38 °C) may negatively influence ANS recovery and function 24 h post exercise and progressively worsen.

Impact of exercise training duration on obesity and cardiometabolic biomarkers: a systematic review.

Physical exercise deters the risk and reduce the adjusted Odds Ratio related to obesity and cardiometabolic diseases but the amount of physical exercise required for initiating those potential advantageous developments in the human body for normal obese individuals is still debatable and thus made many face the health burden during pandemic, despite of their claiming to be physically active. The primary aim of this review was to find an ideal duration and form of exercise that could help reduce the risk of cardiometabolic diseases and its complications for subjects with obesity and deranged cardiometabolic risk markers. Electronic database PubMed/MedLine, Scopus and PEDro for available literature on Experimental studies and RCT on exercise prescription and its effect on anthropometric measurements as well as key biomarkers in obese individuals, 451 records were procured, 47 full text articles were identified to assess eligibility criteria out of which 19 were finally included in the review. There exists a strong association between cardiometabolic profile and physical activity, poor diet, sedentary lifestyle and continuous exercises for longer duration can lead to reduction in obesity and subjects with cardiometabolic diseases. Various confounding factors that may affect the outcome of physical activity training have not been considered in a standard format by all the authors in the articles reviewed. There was variation in duration of physical activity and energy expenditure required for inducing the changes in different cardiometabolic biomarkers.

Hybrid Functional Electrical Stimulation Improves Anaerobic Threshold in First Three Years after Spinal Cord Injury.

The purpose of the present investigation was to assess the effects of whole-body exercise on the anaerobic threshold in individuals with spinal cord injury (SCI). Maximal oxygen uptake (VO2max) and oxygen uptake at anaerobic threshold (AT) were measured before and after six months of hybrid functional electrical stimulation row training in 47 participants with SCI aged 19-63, neurological levels of injury C4-L1, American Spinal Injury Association Impairment Scale grades A-D, and time since injury at enrollment from three months to 40 years. Changes in VO2max differed with time since injury, with greater increases earlier post-injury. The early chronic group (<3 years since injury; n = 31) increased VO2max from 1.65 ± 0.54 L/min at baseline to 1.83 ± 0.66 L/min at six months (p < 0.05), while the late chronic group (>3 years since injury; n = 16) did not change (1.42 ± 0.44 at baseline to 1.47 ± 0.41 L/min at six months, p = 0.36). Consistent with VO2max changes, AT increased in the early chronic group (1.03 ± 0.31 to 1.20 ± 0.40 L/min, p < 0.05) and did not change in the late chronic group (0.99 ± 0.31 to 0.99 ± 0.26 L/min, p = 0.92). Cumulative duration of exercise training was positively correlated to change in VO2max (r = 0.475, p < 0.05) but not to change in AT. Hybrid functional electrical stimulation row training is effective for increasing aerobic capacity and anaerobic threshold in individuals with SCI; however, these fitness benefits are only significant in individuals initiating the exercise intervention within three years of injury.

Sex-Specific Impacts of Exercise on Cardiovascular Remodeling.

Cardiovascular diseases (CVD) remain the leading cause of death in men and women. Biological sex plays a major role in cardiovascular physiology and pathological cardiovascular remodeling. Traditionally, pathological remodeling of cardiovascular system refers to the molecular, cellular, and morphological changes that result from insults, such as myocardial infarction or hypertension. Regular exercise training is known to induce physiological cardiovascular remodeling and beneficial functional adaptation of the cardiovascular apparatus. However, impact of exercise-induced cardiovascular remodeling and functional adaptation varies between males and females. This review aims to compare and contrast sex-specific manifestations of exercise-induced cardiovascular remodeling and functional adaptation. Specifically, we review (1) sex disparities in cardiovascular function, (2) influence of biological sex on exercise-induced cardiovascular remodeling and functional adaptation, and (3) sex-specific impacts of various types, intensities, and durations of exercise training on cardiovascular apparatus. The review highlights both animal and human studies in order to give an all-encompassing view of the exercise-induced sex differences in cardiovascular system and addresses the gaps in knowledge in the field.

Exercise Training Duration and Intensity Are Associated With Thicker Carotid Intima-Media Thickness but Improved Arterial Elasticity in Active Children and Adolescents.

Even though exercise generally has a positive effect on health, intensive exercise can have adverse effects on the vascular system of adults. This study aimed to investigate the association between training duration and intensity and vascular structure and function in 427 physically active children and adolescents (14.0 ± 1.94 years). In this study, we examined carotid intima-media thickness (cIMT), carotid diameter, and cIMT:diameter-ratio as parameters of carotid arterial structure and arterial compliance (AC), stiffness index β (β), elastic modulus (Ep), and carotid pulse wave velocity (PWVβ) as parameters of carotid arterial function with high-resolution ultrasound. We collected central systolic blood pressure (cSBP) and aortic pulse wave velocity (aPWV) as parameters of central arterial stiffness with an oscillometric device. We used the MoMo Physical Activity Questionnaire to record training duration and intensity. Training duration (p = 0.022) and intensity (p = 0.024) were associated with higher cIMT. Further, training duration was associated with lower central arterial stiffness (cSBP: p = 0.001; aPWV: p = 0.033) and improved AC (p < 0.001). Higher training intensity was related to improved AC (p < 0.001) and larger carotid diameter (p = 0.040). Boys presented thicker cIMT (p = 0.010), improved AC (p = 0.006), and lower central arterial stiffness (cSBP: p < 0.001; aPWV: p = 0.016) associated with higher training duration. Girls presented improved AC (p = 0.023) and lower Ep (p = 0.038) but higher β (p = 0.036) associated with higher training duration. Only boys demonstrated thicker cIMT (p = 0.016) and improved AC (p = 0.002) associated with higher training intensity. A quintile analyses of the training duration revealed thicker cIMT of children and adolescents in Q1 and Q5 than that in Q4 and Q5. Besides, Q1 showed lower cSBP compared to Q4 and Q5. Regarding training intensity, Q5 had thicker cIMT than Q2 and Q3. Although a higher training load is associated with thicker cIMT, the common carotid artery is also more elastic. This suggests that a higher training load leads to a functional adaptation of the carotid artery in youth.

A Preventive Role of Exercise Across the Coronavirus 2 (SARS-CoV-2) Pandemic.

The coronavirus 2019 (COVID-19) pandemic has posed a significant threat to human health around the world. A severe risk of infection has been observed in elderly populations. In addition, individuals with obesity and obesity-related comorbidities have also been identified to be at a higher risk of infection for COVID-19. We have attempted here to provide evidence in support of exercise management as a prevention strategy for improving health and minimizing the effects of COVID-19. Therefore, exercise duration, frequency, and intensity benefits are summarized in an attempt to provide guidelines for the general population. In terms of exercise effects, there are multiple benefits of exercise related to human health. These include, decreases in adipose tissue, improvements in cardio-respiratory fitness, enhanced metabolic homeostasis, and suppress inflammation active. With respect to the amount of exercise performed individuals should exercise at a moderate intensity for at least 150 min/wk as an initial target. Increases in intensity and duration of exercise training are necessary for significant fitness benefits, weight loss, and prevention of weight regain. In relation to walking, 10,000 steps/day at a rate of 64–170 steps/minute for at least 10 min duration is reasonable for healthy adults. For exercise intensity, a combination of resistance training (RT), aerobic training (AT) as well as high-intensity interval training (HIIT) incorporated with moderate-intensity continuous training (MICT) can be recognized as an optimal exercise mode for health benefits. Aerobic training and MICT should be viewed as a basis for exercise in combination with appropriate volumes and types of RT and HIIT. Activities should be performed according to professional guidelines and advice. If implemented, these measures may reduce infection rates, underlying pathologies, and assist in decreasing mortality associated with COVID-19 pandemic.

Cardiometabolic Benefit Of A Family-Oriented Exercise And Nutrition Intervention On Overweight And Obese Children

One third of U.S. children are overweight or obese. Without intervention, they experience an elevated risk of developing type 2 diabetes and cardiovascular disease as adults. Poor blood glucose and lipid profiles are indicators of adult onset, and early intervention can reduce the likelihood of future diagnosis. Thus, it is important to identify programs capable of improving these parameters in at-risk children. PURPOSE: To examine the effect of a family-oriented exercise and nutrition intervention on blood glucose and lipid profiles in overweight and obese children. METHODS: 12 children (age 7-16 yr) were referred to a weight loss intervention by their primary care physician; 6 males and 3 females completed the program. They performed biweekly sessions of structured exercise (45 min) and nutritional counseling (30 min) for 18 weeks. At baseline and follow-up, blood samples were drawn, measuring triglycerides (TG), total cholesterol (TC), high-density lipoproteins (HDL), low-density lipoproteins (LDL), and blood glucose (BG). Paired-samples t-tests compared pre to post differences in these variables. RESULTS: At baseline, subjects were 12.3±2.4 years old with a body mass index of 29.8±4.5 kg/m2. Blood samples revealed TG of 118.4±50.1 mg/dL, TC of 172.0±21.2 mg/dL, HDL of 52.6±10.2 mg/dL, LDL of 97.8±24.9 mg/dL, and BG of 117.25±5.4 mg/dL. From baseline to follow-up, non-significant improvements were detected in TG (p=0.104), TC (p=0.085), and LDL (p=0.132). Significant changes were detected in HDL (increased 6.8±2.2 mg/dL, corresponding to a 13.1% improvement; p=0.009) and BG (decreased 17.7±5.0 mg/dL, 14.8% improvement; p=0.026). CONCLUSION: Despite the absence of external incentives, the program’s retention was 75% over 18 weeks. Children who completed the full duration of exercise training and nutritional counseling experienced significant improvements in HDL and BG. These findings support the growing evidence that earlier cardiometabolic interventions are warranted.

Routine exercise-based cardiac rehabilitation does not increase aerobic fitness: A CARE CR study

BackgroundRecent evidence suggests that routine exercise-based cardiac rehabilitation (CR) may not lead to a substantial increase in estimated peak oxygen uptake (V̇O2peak). This could reduce the potential benefits of CR and explain why CR no longer improves patient survival in recent studies. We aimed to determine whether routine exercise-based CR increases V̇O2peak using gold-standard maximal cardiopulmonary exercise testing (CPET), and to quantify the exercise training stimulus which might be insufficient in patients undertaking CR. MethodsWe studied the effects of a routine, twice weekly, exercise-based CR programme for eight weeks (intervention group) compared with abstention from supervised exercise training (control group) in patients with coronary heart disease. The primary outcome was V̇O2peak measured using CPET. We also measured changes in body composition using dual X-ray absorptiometry, carotid intima-media thickness, hs-CRP and N-terminal pro B-type natriuretic peptide at baseline, 10 weeks and 12 months. We also calculated the Calibre 5-year all-cause mortality risk score. ResultsSeventy patients (age 63.1 SD10.0 years; BMI 29.2 SD4.0 kg·m−2; 86% male) were recruited (n = 48 intervention; n = 22 controls). The mean aerobic exercise training duration was 23 min per training session, and the mean exercise training intensity was 45.9% of heart rate reserve. V̇O2peak was 23·3 ml·kg-1·min−1 at baseline, and there were no changes in V̇O2peak between groups at any time point. The intervention had no effect on any of the secondary endpoints. ConclusionRoutine CR does not lead to an increase in V̇O2peak and is unlikely to improve long-term physiological outcomes.

Effects of long-term exercise training for different durations on pancreatic amylase activity and intestinal glucose transporter content in rats.

Long‐term endurance training for a relatively short duration (~1 h) is reported to increase pancreatic amylase activity in rats, suggesting that chronic exercise training enhances carbohydrate digestive capacity. However, it remains unknown whether longer exercise training duration results in greater adaptation in the pancreas and small intestine. Thus, this study aimed to examine the effects of long‐term endurance training for a longer duration on pancreatic amylase activity and intestinal glucose transporter content in rats. Male Sprague–Dawley rats were subjected to swimming exercise training for 1 h (Ex‐1h group) or 6 h (Ex‐6h group, two 3‐h sessions separated by 1 h of rest) each day, 5 days a week, for 6 weeks. Sedentary rats were used as a control (Con group). Total pancreatic amylase activity in the Ex‐6h group was significantly lower than that in the Con and Ex‐1h groups immediately after the last training session. After 24 h of recovery, total pancreatic amylase activity was significantly higher in the Ex‐1h group (~46%) than in the Con group, and a further increase was observed in the Ex‐6h group (~98%). In addition, the Ex‐6h group, but not the Ex‐1h group, showed significantly greater intestinal sodium‐dependent glucose transporter 1 (SGLT1) content compared with the Con group after 24 h of recovery. However, no significant difference was observed in glucose transporter 2 (GLUT2) content among the three groups. In conclusion, chronic endurance exercise training for a longer duration results in larger increases in pancreatic amylase activity and intestinal SGLT1 content in rats.

Impairment between Oxidant and Antioxidant Systems: Short- and Long-term Implications for Athletes' Health.

The role of oxidative stress, an imbalance between reactive oxygen species production (ROS) and antioxidants, has been described in several patho-physiological conditions, including cardiovascular, neurological diseases and cancer, thus impacting on individuals’ lifelong health. Diet, environmental pollution, and physical activity can play a significant role in the oxidative balance of an organism. Even if physical training has proved to be able to counteract the negative effects caused by free radicals and to provide many health benefits, it is also known that intensive physical activity induces oxidative stress, inflammation, and free radical-mediated muscle damage. Indeed, variations in type, intensity, and duration of exercise training can activate different patterns of oxidant–antioxidant balance leading to different responses in terms of molecular and cellular damage. The aim of the present review is to discuss (1) the role of oxidative status in athletes in relation to exercise training practice, (2) the implications for muscle damage, (3) the long-term effect for neurodegenerative disease manifestations, (4) the role of antioxidant supplementations in preventing oxidative damages.

Effects of exercise training on cardiac function, exercise capacity, and quality of life in heart failure with preserved ejection fraction: a meta-analysis of randomized controlled trials.

Left ventricular (LV) diastolic dysfunction is associated with the pathophysiology of heart failure with preserved ejection fraction (HFpEF) and contributes importantly to exercise intolerance that results in a reduced quality of life (QOL) in HFpEF patients. Although the effects of exercise training on LV diastolic function, exercise capacity, or QOL in HFpEF patients have been examined in randomized clinical trials (RCTs), results are inconsistent due partly to limited power with small sample sizes. We aimed to conduct a meta-analysis of RCTs examining the effects of exercise training on LV diastolic function and exercise capacity as well as QOL in HFpEF patients. The search of electronic databases identified 8 RCTs with 436 patients. The duration of exercise training ranged from 12 to 24weeks. In the pooled analysis, exercise training improved peak exercise oxygen uptake (weighted mean difference [95% CI], 1.660 [0.973, 2.348] ml/min/kg), 6-min walk distance (33.883 [12.384 55.381] m), and Minnesota Living With Heart Failure Questionnaire total score (9.059 [3.083, 15.035] point) compared with control. In contrast, exercise training did not significantly change early diastolic mitral annular velocity (weighted mean difference [95% CI], 0.317 [- 0.952, 1.587]cm/s), the ratio of early diastolic mitral inflow to annular velocities (- 1.203 [- 4.065, 1.658]), or LV ejection fraction (0.850 [- 0.128, 1.828] %) compared with control. In conclusion, the present meta-analysis suggests that exercise training improves exercise capacity and QOL without significant change in LV systolic or diastolic function in HFpEF patients.

Distinct patterns of skeletal muscle mitochondria fusion, fission and mitophagy upon duration of exercise training

Healthy ageing interventions encompass regular exercise to prevent mitochondrial dysfunction, key player in sarcopenia pathogenesis. Mitochondrial biogenesis has been well documented, but mitochondrial remodelling in response to exercise training is poorly understood. Here we investigated fusion, fission and mitophagy before and after an exercise intervention in older adults. Skeletal muscle biopsies were collected from 22 healthy sedentary men and women before and after 4months of supervised training. Eight lifelong trained age- and gender-matched volunteers served as positive controls. Transmission electron microscopy was used to estimate mitochondrial content. Western blotting and qRT-PCR were used to detect changes in specific proteins and transcripts. After intervention, mitochondrial content increased to levels of controls. While enhancement of fusion was prevalent after intervention, inhibition of fission and increased mitophagy were dominant in controls. Similarly to PARKIN, BCL2L13 content was higher in controls. The observed molecular adaptations paralleled long-term effects of training on physical fitness, exercise efficiency and oxidative capacity. This study describes distinct patterns of molecular adaptations in human skeletal muscle under chronic exercise training. After 16weeks of exercise, the pattern was dominated by fusion to increase mitochondrial content to the metabolic demands of exercise. In lifelong exercise, the pattern was dominated by mitophagy synchronized with increased fusion and decreased fission, indicating an increased mitochondrial turnover. In addition to these temporally distinct adaptive mechanisms, this study suggests for the first time a specific role of BCL2L13 in chronic exercise that requires constant maintenance of mitochondrial quality.

The Effects of Exercise Training on Brachial Artery Flow-Mediated Dilation: A Meta-analysis.

Flow-mediated dilation, a barometer of cardiovascular (CV) health, is reported to increase with exercise training (ET); however, the potential moderating factors of ET are not clear to date. The purpose of this study was to determine the effect of ET assessed by brachial artery flow-mediated dilation (BAFMD). Authors searched PubMed between January 1999 and December 2013, bibliographies, and reviews to identify studies examining ET and BAFMD. Two independent reviewers extracted quality, descriptive, exercise, and outcome data of eligible studies. Data were presented as weighted effect sizes (ESs) and 95% confidence limits. Analysis included 66 studies reporting BAFMD data (1865 ET and 635 control subjects). Overall, ET had significant improvements in BAFMD compared with controls (P < .0001). Exercise training at higher ET intensities resulted in a greater increase in BAFMD (9.29; 95% CI, 5.09-13.47) than lower ET intensities (3.63; 95% CI, -0.56 to 7.83) or control (-0.42; 95% CI, -2.06 to 1.21). Subjects whose ET duration was ≥150 min/wk (11.33; 95% CI, 7.15-15.51) had a significant improvement in BAFMD compared with those with <150 min/wk (4.79; 95% CI, 3.08-6.51) or control (-0.30; 95% CI, -1.99 to 1.39). Age (P = .11) and baseline artery diameter (P = .31) did not modify the BAFMD response to ET. Exercise training contributes to a significant increase in BAFMD. These results provide indirect evidence that ET alters a well-known factor associated with the primary and secondary prevention of CV diseases. Exercise training interventions, including greater intensity and duration, may optimize the increase in BAFMD.

Effects of a 12-week exercise training on insulin sensitivity, quality of life, and depression status in patients with type 2 diabetes

Background: Exercise is one of the optimal and alternative treatments for type 2 diabetes (T2DM). Although the effect of a single bout of exercise on insulin sensitivity is reported to persist only for 2–3 days, effects remain unclear of a 12-week aerobic exercise training on insulin sensitivity, quality of life (QOL), and depression status over time as exercise training duration increases in patients with T2DM. Objectives: To investigate the effects over time in patients with T2DM of a 12-week aerobic exercise training on insulin sensitivity, QOL, and depression status. Materials and Methods: Purposive sampling was used to recruit 17 T2DM patients. Participants underwent a 12-week, supervised, moderate-intensity aerobic exercise training three times per week, 30 min per session. Outcome indicators including insulin sensitivity (measured by a 2-h oral glucose tolerance test [OGTT] and homeostatic model assessment-insulin resistance [HOMA-IR]), QOL (Medical Outcomes Study Short Form 36), and depression status (beck depression inventory scale) were evaluated at baseline and at 4-week intervals. Results: A final 13 eligible participants completed the study. For every 4-week increase in duration of exercise training, there was an increase over time in insulin sensitivity, including a decrease over time in OGTT glucose area under the curve of 66.92 min/mmol/L. Glucose concentrations decreased over time at 60, 90, and 120 min after an oral glucose challenge. Further, the HOMA-IR decreased over time as the duration of exercise training increased. QOL and depression status improved significantly during the training. Conclusions: Moderate-intensity exercise training improves insulin sensitivity, QOL, and depression status in T2DM patients, particularly over time within a 12-week exercise training course.

Relative Effectiveness of Exercise Training, Versus Pharmacotherapies in Heart Failure with Preserved Ejection Fraction: A Meta-Analysis Focussing on Exercise Outcomes

Background: Heart failure with preserved ejection fraction (HFpEF) is a common disorder, associated with congestive episodes, and/or symptoms attributable to heart failure. No therapy has been shown to improve long-term outcomes. However, as exertional intolerance is a major symptom burden, numerous Phase II studies have utilised exercise endpoints as an indicator of benefit. Methods: We undertook a quantitative review of studies published as of October 2016 by searching PubMed, Embase and clinicaltrials.gov, combining terms related to the population (i.e. HFpEF) with terms for the outcomes (e.g, VO2peak, aerobic capacity, etc.). Random effects meta-analysis on the mean difference in raw change scores was performed with subgroup analysis for exercise and pharmaceutical studies. Results: Five exercise and 10 pharmaceutical trials were included the meta-analysis of aerobic capacity (VO2peak and 6 minute walk distance [6MWD]). For exercise studies, exercise training duration ranged from 6-16 weeks and included aerobic based regimes performed 2-3 times per week at 40-70% of VO2peak. Pharmaceutical trials examined ivabradine, sildenafil, ACE-inhibition, angiotensin receptor blockade, beta-adrenergic antagonists and mineralocorticoid receptor antagonists. On average, exercise increased VO2peak by 2.41 ml/kg/min, (95% CI: 1.8, 3.02) while pharmaceutical interventions did not exhibit any effect (-0.04 ml/kg/min, 95% CI: -0.64, 0.56). 6MWD was improved following exercise by 39 m (95% CI: 13, 65), but not by pharmaceutical intervention (-4 m; 95% CI: -16, 7). Conclusion: Exercise training exhibited a strong effect on indices of functional capacity. In contrast, the pharmacotherapies tested thus far do not improve exercise tolerance.

Response.

Dear Editor-in-Chief We appreciate the interest of such influential colleagues in our recent meta-analysis (5). Point-by-point responses to their comments are presented below: In our view, experts in meta-analysis concur that “The Cochrane Risk of Bias Assessment” tool is designed to evaluate randomized controlled trials, which have yet to be performed on the topic of the current meta-analysis. Likewise, PRISMA, but not MOOSE, guidelines focus on randomized controlled trials. An identical comment concerning arteriovenous oxygen difference (a-vO2diff) is acknowledged and fully addressed in the manuscript. The training study of Roca et al. (8) reported neither maximal cardiac output (max) nor a-vO2diff (i.e., the outcomes required for the present meta-analysis); therefore, that study cannot be included. Of note, the process of article selection is straightforward and thoroughly described (5).We concur with the prevailing notion that any variable potentially influenced by exercise training (ExT) may be modified more with ExT in untrained versus trained individuals. If, however, such a variable (e.g., a-vO2diff at maximal exercise) is close to optimal levels in the untrained state, ExT will induce a less marked effect. This conjecture is firmly opposed by “the null heterogeneity among studies and the associations between the standardized mean differences (SMDs) in max and V˙O2max (P = 0.006), and the SMD in a-vO2diff and duration of training (P = 0.0002)” ([5], p. 2031). To relieve our colleagues’ main concern, the meta-analysis reveals that a-vO2diff is indeed increased with ExT, when this lasts 12 or more weeks (5). This finding has also been observed in healthy age individuals (4). With shorter (5–11 wk) ExT duration, max, but not a-vO2diff, is increased irrespective of age, according to 18 studies comprising nearly 200 individuals (4,5). Moreover, Poole et al. (7) seem to ignore solid human experimental proof demonstrating that the increase in V˙O2max with short-term (6 wk) ExT is abolished when the increase in max is manipulated to pretraining values—despite the presence of skeletal muscle adaptations, including increases in capillarization and mitochondrial content (3). Poole et al. (7) appear to perceive a-vO2diff as an equivalent of muscle O2 diffusing capacity (DO2m), which it is not. DO2m is computed as V˙O2 divided by the muscle O2 pressure gradient (9); thus, it is intrinsically determined by strict muscle O2 diffusing capacity and convective O2 delivery, which in turn is primarily a function of muscle blood flow. Accordingly, it cannot be discarded that DO2m increases with ExT are essentially the consequence of enhanced max leading to augmented muscle blood flow. In addition, our colleagues seem to rely on a theoretical model (9) based on untenable assumptions (6) to speculate that any potential increase in V˙O2max should, at least in part, be limited by skeletal muscle attributes determining DO2m. The collapse of their model is strikingly evident, considering the aforementioned unequivocal evidence (3) and experimental data gathered for a century in humans and other vertebrates (2). Furthermore, recent (again apparently unnoticed) catheterization studies demonstrate a twofold functional reserve in DO2m at V˙O2max in healthy untrained individuals (1). Ultimately, caution should be exercised before proposing therapeutic interventions only targeting skeletal muscle adaptations if attempting to improve V˙O2max substantially. David Montero Zurich Center for Integrative Human Physiology Institute of Physiology, University of Zurich Zurich, SWITZERLAND Candela Diaz-Cañestro Center for Molecular Cardiology University of Zurich Schlieren, SWITZERLAND Carsten Lundby Zurich Center for Integrative Human Physiology Institute of Physiology, University of Zurich Zurich, SWITZERLAND

Functional changes in deep dorsal horn interneurons following spinal cord injury are enhanced with different durations of exercise training.

Exercise training after spinal cord injury (SCI) enhances collateral sprouting from axons near the injury and is thought to promote intraspinal circuit reorganisation that effectively bridges the SCI. The effects of exercise training, and its duration, on interneurons in these de novo intraspinal circuits are poorly understood. In an adult mouse hemisection model of SCI, we used whole-cell patch-clamp electrophysiology to examine changes in the intrinsic and synaptic properties of deep dorsal horn interneurons in the vicinity of a SCI in response to the injury, and after 3 and 6 weeks of treadmill exercise training. SCI alone exerted powerful effects on the intrinsic and synaptic properties of interneurons near the lesion. Importantly, synaptic activity, both local and descending, was preferentially enhanced by exercise training, suggesting that exercise promotes synaptic plasticity in spinal cord interneurons that are ideally placed to form new intraspinal circuits after SCI. Following incomplete spinal cord injury (SCI), collaterals sprout from intact and injured axons in the vicinity of the lesion. These sprouts are thought to form new synaptic contacts that effectively bypass the lesion epicentre and contribute to improved functional recovery. Such anatomical changes are known to be enhanced by exercise training; however, the mechanisms underlying exercise-mediated plasticity are poorly understood. Specifically, we do not know how SCI alone or SCI combined with exercise alters the intrinsic and synaptic properties of interneurons in the vicinity of a SCI. Here we use a hemisection model of incomplete SCI in adult mice and whole-cell patch-clamp recording in a horizontal spinal cord slice preparation to examine the functional properties of deep dorsal horn (DDH) interneurons located in the vicinity of a SCI following 3 or 6 weeks of treadmill exercise training. We examined the functional properties of local and descending excitatory synaptic connections by recording spontaneous excitatory postsynaptic currents (sEPSCs) and responses to dorsal column stimulation, respectively. We find that SCI in untrained animals exerts powerful effects on intrinsic, and especially, synaptic properties of DDH interneurons. Plasticity in intrinsic properties was most prominent at 3 weeks post SCI, whereas synaptic plasticity was greatest at 6 weeks post injury. Exercise training did not markedly affect intrinsic membrane properties; however, local and descending excitatory synaptic drive were enhanced by 3 and 6 weeks of training. These results suggest exercise promotes synaptic plasticity in spinal cord interneurons that are ideally placed to form new intraspinal circuits after SCI.

Home-based resistance training for older adults: a systematic review.

Home-based resistance exercise is commonly used for individuals who might not have access or the ability to use traditional resistance exercise. However, the extent to which home-based resistance exercise can improve both strength and functional ability has not been investigated in healthy older individuals using a systematic analysis. The current article systematically reviewed the effectiveness of home-based resistance exercise on strength and functional ability. Search engines included Academic Search Premier, CINAHL, PubMed, PsycINFO, MEDLINE, SPORTDiscus and Web of Science. A total of 649 articles were found using the key words "home-based" and "strength" and "older" or "elderly", with eight articles meeting the final criteria. The average age of the participants was 76 years, with the average duration of exercise training ranging from 8 weeks to 120 weeks. Of the eight studies, a significant increase in knee extension strength was found in five studies. Functional ability significantly improved in seven of the eight studies, with the average decrease in Timed Up & Go test being -0.8 ± 0.5 s. Three studies included greater amounts of supervised visits compared with the other five studies (∼51% vs ∼7%). The more supervised studies had significant increases in strength and functional ability. Overall, home-based resistance exercise can improve both strength and functional ability, but the improvements are generally small. The intensity of the exercises might not progress sufficiently enough to produce large improvements in strength as a result of less supervision or a lack of motivation to increase the intensity further.

Differential effect of exercise training duration on bone tissue in male obese rat

The association of a well-balanced diet with exercise is a key strategy to treat obesity. Whereas exercise is known to induce beneficial effects on bone, data concerning these effects in a weight loss program in rat are lacking. Because weight loss is linked to a concomitant bone loss, we wondered if exercise training duration may differently affect the bone tissue in such a program. This study aimed to investigate bone responses to two different durations of exercise training combined with a well-balance diet in obese rats. Fifty nine Wistar male rats were previously fed with a high fat/high sucrose diet (HF/HS) for 4 months to induce obesity. A control group (n = 15) was fed with a standard diet (HF/HS vs. Control = T0). Then, all rats were given a well-balanced diet and assigned to 4 different modalities: one month of exercise training (treadmill: 50 min/day, 5 days/week) or sedentarity (T1), two months of exercise or sedentarity (T2). The body composition and BMD were assessed by DXA. Visceral fat mass was weighed and insulin sensitivity was tested. Trabecular micro-architecture of tibia and L2 vertebrae (L2) and the cortical analysis of tibia were performed by 3D microtomography. Osteocalcin and CTX levels were assessed. At T0, the HF/HS diet group had developed a total and abdominal obesity and an impaired glucose tolerance compared with the Control group (p < 0.05). Most of the bone parameters were improved in HF/HS group vs. the Control group: higher total BMC and BMD, lower cortical porosity of tibia and higher Tb.Th of L2 (p < 0.05). One month of exercise (T1) had not affected the body composition and bone parameters except an improvement of insulin sensitivity (p < 0.05) and a tendency to increase BV/TV of tibia (p < 0.06). At T2, the total and fat masses were reduced in exercised group vs. sedentary group (p < 0.01). Regarding the bone parameters, CTX level decreased (p < 0.05), the Tb.Sp of L2 tended to decrease (p < 0.06), the degree of anisotropy (DA) of tibia increased (p < 0.05), and DA of L2 tended to increase (p < 0.06) in exercised group vs. sedentary group. In conclusion, 2 months of exercise had reduced obesity parameters, decreased resorption and improved a part of trabecular parameters of bone tissue whereas 1 month of exercise did not induce such improvement. A two-month program composed of a well balanced diet combined with exercise training is able to treat obesity and to protect bone tissue in male obese rat whereas one month program is not efficient.