Performance Benefits of Pre- and Per-cooling on Self-paced Versus Constant Workload Exercise:A Systematic Review and Meta-analysis

BACKGROUND AND OBJECTIVE: Exercise in hot environments impairs endurance performance. Cooling interventions can attenuate the impact of heat stress on performance, but the influence of an exercise protocol on the magnitude of performance benefit remains unknown. This meta-analytical review compared the effects of pre- and per-cooling interventions on performance during self-paced and constant workload exercise in the heat.METHODS: The study protocol was preregistered at the Open Science Framework ( https://osf.io/wqjb3 ). A systematic literature search was performed in PubMed, Web of Science, and MEDLINE from inception to 9 June, 2023. We included studies that examined the effects of pre- or per-cooling on exercise performance in male individuals under heat stress (&gt; 30 °C) during self-paced or constant workload exercise in cross-over design studies. Risk of bias was assessed using the Cochrane Risk of Bias Tool for randomized trials.RESULTS: Fifty-nine studies (n = 563 athletes) were identified from 3300 records, of which 40 (n = 370 athletes) used a self-paced protocol and 19 (n = 193 athletes) used a constant workload protocol. Eighteen studies compared multiple cooling interventions and were included more than once (total n = 86 experiments and n = 832 paired measurements). Sixty-seven experiments used a pre-cooling intervention and 19 used a per-cooling intervention. Average ambient conditions were 34.0 °C [32.3-35.0 °C] and 50.0% [40.0-55.3%] relative humidity. Cooling interventions attenuated the performance decline in hot conditions and were more effective during a constant workload (effect size [ES] = 0.62, 95% confidence interval [CI] 0.44-0.81) compared with self-paced exercise (ES = 0.30, 95% CI 0.18-0.42, p = 0.004). A difference in performance outcomes between protocols was only observed with pre-cooling (ES = 0.74, 95% CI 0.50-0.98 vs ES = 0.29, 95% CI 0.17-0.42, p = 0.001), but not per-cooling (ES = 0.45, 95% CI 0.16-0.74 vs ES = 0.35, 95% CI 0.01-0.70, p = 0.68).CONCLUSIONS: Cooling interventions attenuated the decline in performance during exercise in the heat, but the magnitude of the effect is dependent on exercise protocol (self-paced vs constant workload) and cooling type (pre- vs per-cooling). Pre-cooling appears to be more effective in attenuating the decline in exercise performance during a constant workload compared with self-paced exercise protocols, whereas no differences were found in the effectiveness of per-cooling.</p

The impact of obesity on cardiac troponin levels after prolonged exercise in humans

Elevated cardiac troponin I (cTnI), a marker for cardiac damage, has been reported after high-intensity exercise in healthy subjects. Currently, little is known about the impact of prolonged moderate-intensity exercise on cTnI release, but also the impact of obesity on this response. 97 volunteers (55 men and 42 women), stratified for BMI, performed a single bout of walking exercise (30–50 km). We examined cTnI-levels before and immediately after the exercise bout in lean (BMI < 25 kg/m2, n = 30, 57 ± 19 years), overweight (25 ≤ BMI < 30 kg/m2, n = 29, 56 ± 11 years), and obese subjects (BMI ≥ 30 kg/m2, n = 28, 53 ± 9 years). Walking was performed at a self-selected pace. cTnI was assessed using a high-sensitive cTnI-assay (Centaur; clinical cut-off value ≥0.04 μg/L). We recorded subject characteristics (body weight, blood pressure, presence of cardiovascular risk) and examined exercise intensity by recording heart rate. Mean cTnI-levels increased significantly from 0.010 ± 0.006 to 0.024 ± 0.046 μg/L (P < 0.001). The exercise-induced increase in cTnI was not different between lean, overweight and obese subjects (two-way ANOVA interaction; P = 0.27). In 11 participants, cTnI was elevated above the clinical cut-off value for myocardial infarction. Logistic regression analysis identified exercise intensity (P < 0.001), but not BMI, body fat percentage or waist circumference to significantly relate to positive troponin tests. In conclusion, prolonged, moderate-intensity exercise results in a comparable increase in cTnI-levels in lean, overweight and obese subjects. Therefore, measures of obesity unlikely relate to the magnitude of the post-exercise elevation in cTnI

Global and regional cardiac function in lifelong endurance athletes with and without myocardial fibrosis

The aim of the present study was to compare cardiac structure as well as global and regional cardiac function in athletes with and without myocardial fibrosis (MF). Cardiac magnetic resonance imaging with late gadolinium enhancement was used to detect MF and global cardiac structure in nine lifelong veteran endurance athletes (58 ± 5 years, 43 ± 5 years of training). Transthoracic echocardiography using tissue-Doppler and myocardial strain imaging assessed global and regional (18 segments) longitudinal left ventricular function. MF was present in four athletes (range 1–8 g) and not present in five athletes. MF was located near the insertion points of the right ventricular free wall on the left ventricle in three athletes and in the epicardial lateral wall in one athlete. Athletes with MF demonstrated a larger end diastolic volume (205 ± 24 vs 173 ± 18 ml) and posterior wall thickness (11 ± 1 vs 9 ± 1 mm) compared to those without MF. The presence of MF did not mediate global tissue velocities or global longitudinal strain and strain rate; however, regional analysis of longitudinal strain demonstrated reduced function in some fibrotic regions. Furthermore, base to apex gradient was affected in three out of four athletes with MF. Lifelong veteran endurance athletes with MF demonstrate larger cardiac dimensions and normal global cardiac function. Fibrotic areas may demonstrate some co-localised regional cardiac dysfunction, evidenced by an affected cardiac strain and base to apex gradient. These data emphasize the heterogeneous phenotype of MF in athletes

Outcomes after cardiac rehabilitation in patients following repair of thoracic aortic aneurysm or dissection: a protocol for a systematic review and meta-analysis.

BACKGROUND Patients receiving thoracic aortic repair suffer from long-term impairment in daily functioning and quality of life following intervention due to a combination of their life-threatening condition (i.e. aortic aneurysm or dissection), undergoing major surgery, as well as long-term exercise restrictions thereafter. Despite the known risks of exercise, it is vital that patients regain physical activity in order to recover their daily functioning and quality of life. Cardiac rehabilitation could be a safe and effective treatment to support patients to become physically active by providing exercise training, comprehensive rehabilitation services, and safety recommendations. Despite new insights in recent literature and clinical practice, international guidelines do not recommend cardiac rehabilitation due to limited evidence. We aim to fill this knowledge gap by performing a systematic review and meta-analysis on the effectiveness of cardiac rehabilitation in patients following thoracic aortic repair. METHODS This protocol has been developed following the Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols (PRISMA-P). MEDLINE, Embase, and CINAHL will be searched for eligible observational and interventional studies from inception up to April 2022. Screening (title/abstract and full text), data extraction, risk of bias assessment, and therapeutic validity rating will be conducted by two independent reviewers. A random-effects model will be used to meta-analyse performance-based outcomes, patient-reported outcomes, clinician-reported outcomes, and researcher-reported outcomes. Subsequently, meta-bias and confidence in evidence will be analysed by two independent reviewers. DISCUSSION To exercise or not to exercise in patients following thoracic aortic repair has been a topic of discussion for years. The intended systematic review and meta-analysis will provide comprehensive evidence on the effectiveness of phase III outpatient exercise-based cardiac rehabilitation in patients following thoracic aortic repair. Findings from this review may inform future guidelines for the management of patients with thoracic aortic disease. SYSTEMATIC REVIEW REGISTRATION PROSPERO CRD42022301204

Impact of lifelong exercise training on endothelial ischemia-reperfusion and ischemic preconditioning in humans.

Reperfusion is essential for ischemic tissue survival, but causes additional damage to the endothelium (i.e. ischemia-reperfusion [IR] injury). Ischemic preconditioning (IPC) refers to short repetitive episodes of ischemia that can protect against IR. However, IPC efficacy attenuates with older age. Whether physical inactivity contributes to the attenuated efficacy of IPC to protect against IR injury in older humans is unclear. We tested the hypotheses that lifelong exercise training relates to 1) attenuated endothelial IR and 2) maintained IPC efficacy that protects veteran athletes against endothelial IR. In 18 sedentary male individuals (SED, 20 years, 63±7 years) and 20 veteran male athletes (ATH, >5 exercise hours/week for >20 years, 63±6 years), we measured brachial artery endothelial function with flow-mediated dilation (FMD) before and after IR. We induced IR by 20-minutes of ischemia followed by 20-minutes of reperfusion. Randomized over 2 days, participants underwent either 35-minute rest or IPC (3 cycles of 5-minutes cuff inflation to 220 mmHg with 5-minutes of rest) before IR. In SED, FMD decreased after IR (median [interquartile range]): (3.0% [2.0-4.7] to 2.1% [1.5-3.9], P=0.046) and IPC did not prevent this decline (4.1% [2.6-5.2] to 2.8% [2.2-3.6],P=0.012). In ATH, FMD was preserved after IR (3.0% [1.7-5.4] to 3.0% [1.9-4.1], P=0.82) and when IPC preceded IR (3.2% [1.9-4.2] to 2.8% [1.4-4.6],P=0.18). These findings indicate that lifelong exercise training is associated with increased tolerance against endothelial IR. These protective, preconditioning effects of lifelong exercise against endothelial ischemia-reperfusion may contribute to the cardio-protective effects of exercise training

Device-measured physical activity and cardiometabolic health: the Prospective Physical Activity, Sitting, and Sleep (ProPASS) consortium

Background and Aims: Physical inactivity, sedentary behaviour (SB), and inadequate sleep are key behavioural risk factors of cardiometabolic diseases. Each behaviour is mainly considered in isolation, despite clear behavioural and biological interdependencies. The aim of this study was to investigate associations of five-part movement compositions with adiposity and cardiometabolic biomarkers.Methods: Cross-sectional data from six studies (n = 15 253 participants; five countries) from the Prospective Physical Activity, Sitting and Sleep consortium were analysed. Device-measured time spent in sleep, SB, standing, light-intensity physical activity (LIPA), and moderate-vigorous physical activity (MVPA) made up the composition. Outcomes included body mass index (BMI), waist circumference, HDL cholesterol, total:HDL cholesterol ratio, triglycerides, and glycated haemoglobin (HbA1c). Compositional linear regression examined associations between compositions and outcomes, including modelling time reallocation between behaviours.Results: The average daily composition of the sample (age: 53.7 ± 9.7 years; 54.7% female) was 7.7h sleeping, 10.4h sedentary, 3.1h standing, 1.5h LIPA, and 1.3h MVPA. A greater MVPA proportion and smaller SB proportion were associated with better outcomes. Reallocating time from SB, standing, LIPA, or sleep into MVPA resulted in better scores across all outcomes. For example, replacing 30min of SB, sleep, standing, or LIPA with MVPA was associated with-0.63 (95% confidence interval-0.48,-0.79),-0.43 (-0.25,-0.59),-0.40 (-0.25,-0.56), and-0.15 (0.05,-0.34) kg/m2 lower BMI, respectively. Greater relative standing time was beneficial, whereas sleep had a detrimental association when replacing LIPA/MVPA and positive association when replacing SB. The minimal displacement of any behaviour into MVPA for improved cardiometabolic health ranged from 3.8 (HbA1c) to 12.7 (triglycerides) min/day. Conclusions: Compositional data analyses revealed a distinct hierarchy of behaviours. Moderate-vigorous physical activity demonstrated the strongest, most time-efficient protective associations with cardiometabolic outcomes. Theoretical benefits from reallocating SB into sleep, standing, or LIPA required substantial changes in daily activity.</p

Device-measured physical activity and cardiometabolic health: the Prospective Physical Activity, Sitting, and Sleep (ProPASS) consortium

BACKGROUND AND AIMS: Physical inactivity, sedentary behaviour (SB), and inadequate sleep are key behavioural risk factors of cardiometabolic diseases. Each behaviour is mainly considered in isolation, despite clear behavioural and biological interdependencies. The aim of this study was to investigate associations of five-part movement compositions with adiposity and cardiometabolic biomarkers. METHODS: Cross-sectional data from six studies (n = 15 253 participants; five countries) from the Prospective Physical Activity, Sitting and Sleep consortium were analysed. Device-measured time spent in sleep, SB, standing, light-intensity physical activity (LIPA), and moderate-vigorous physical activity (MVPA) made up the composition. Outcomes included body mass index (BMI), waist circumference, HDL cholesterol, total:HDL cholesterol ratio, triglycerides, and glycated haemoglobin (HbA1c). Compositional linear regression examined associations between compositions and outcomes, including modelling time reallocation between behaviours. RESULTS: The average daily composition of the sample (age: 53.7 ± 9.7 years; 54.7% female) was 7.7 h sleeping, 10.4 h sedentary, 3.1 h standing, 1.5 h LIPA, and 1.3 h MVPA. A greater MVPA proportion and smaller SB proportion were associated with better outcomes. Reallocating time from SB, standing, LIPA, or sleep into MVPA resulted in better scores across all outcomes. For example, replacing 30 min of SB, sleep, standing, or LIPA with MVPA was associated with -0.63 (95% confidence interval -0.48, -0.79), -0.43 (-0.25, -0.59), -0.40 (-0.25, -0.56), and -0.15 (0.05, -0.34) kg/m2 lower BMI, respectively. Greater relative standing time was beneficial, whereas sleep had a detrimental association when replacing LIPA/MVPA and positive association when replacing SB. The minimal displacement of any behaviour into MVPA for improved cardiometabolic health ranged from 3.8 (HbA1c) to 12.7 (triglycerides) min/day. CONCLUSIONS: Compositional data analyses revealed a distinct hierarchy of behaviours. Moderate-vigorous physical activity demonstrated the strongest, most time-efficient protective associations with cardiometabolic outcomes. Theoretical benefits from reallocating SB into sleep, standing, or LIPA required substantial changes in daily activity

Thermoregulation and fluid balance during a 30-km march in 60-versus 80-year-old subjects

The presence of impaired thermoregulatory and fluid balance responses to exercise in older individuals is well established. To improve our understanding on thermoregulation and fluid balance during exercise in older individuals, we compared thermoregulatory and fluid balance responses between sexagenarians and octogenarians during prolonged exercise. Forty sexagenarians (60 ± 1 year) and 36 octogenarians (81 ± 2 year) volunteered to participate in a 30-km march at a self-selected pace. Intestinal temperature (T in) and heart rate were recorded every 5 km. Subjects reported fluid intake, while urine output was measured and sweat rate was calculated. Octogenarians demonstrated a lower baseline T in and a larger exercise-induced increase in T in compared to sexagenarians (1.2 ± 0.5 °C versus 0.7 ± 0.4 °C, p  0.05). These results suggest that thermoregulatory responses deteriorate with advancing age, while fluid balance is regulated appropriately during a 30-km walking march under moderate ambient conditions