Aims: Diabetes poses a growing global health burden. This study investigated the causal effects of lifestyle and socioeconomic factors on diabetes risk and related complications and comorbidities. Materials and Methods: We applied two-sample univariable and multivariable Mendelian randomization to assess the causal impact of 26 lifestyle and socioeconomic factors on diabetes, 7 complications, and 13 comorbidities. Results: Genetically predicted protective factors included vigorous physical activity (odds ratio [OR], 0.98 [0.98-0.99]), computer use time (OR, 0.13 [0.05, 0.30]), carbohydrate intake (OR, 0.22 [0.15, 0.34]), short (OR, 0.04 [0.01, 0.16]) and long sleep duration (OR, 0.62 [0.47, 0.82]), moderate alcohol (OR, 0.13 [0.04, 0.50]) and caffeine (OR, 0.72 [0.64, 0.81]) consumption, education (OR, 0.25-0.67), and household income (OR, 0.52-0.65), which were associated with reduced risks of type 2 and gestational diabetes, stroke, coronary heart disease, heart failure, myocardial infarction, sleep apnea, and anxiety disorder (adjusted P-values <0.05). Conversely, genetically predicted factors, such as television watching (OR, 1.39 [1.23, 1.57]) and driving time (OR, 3.28 [1.27, 8.48]), insomnia (OR, 1.21-1.82), smoking behaviors (OR, 1.17-1.77), alcohol dependence (OR, 1.17-1.28), coffee consumption (OR, 1.01 [1.00, 1.02]), and the Townsend deprivation index (OR, 1.51-1.57), are associated with increased risks of diabetes-related outcomes (i.e., all diabetic types, neovascular glaucoma, heart failure, nonalcoholic fatty liver disease, sleep apnea, and eating disorder) (adjusted P-values <0.05). Conclusions: Our findings support causal roles of lifestyle and socioeconomic factors and diabetes-related outcomes, emphasizing the need for targeted public health strategies to promote healthier living and socioeconomic equity.

Background: Sedentary time can be accumulated through many short periods or fewer prolonged bouts, but longitudinal evidence linking these accumulation patterns to subsequent physical functioning and pain in midlife remains limited. We examined whether a greater proportion of waking sitting/lying time accumulated in bouts lasting at least 30 minutes was associated with subsequent physical functioning and pain burden. Methods: We conducted a longitudinal observational analysis of the 1970 British Cohort Study, linking thigh-worn activPAL data collected at age 46 with health outcomes at age 51. The exposure was the proportion of total waking sitting/lying time accumulated in bouts lasting at least 30 minutes. Outcomes were SF-36 Physical Functioning and pain burden, defined as reverse-scored SF-36 Bodily Pain. Weighted linear regression models incorporated 50 multiple imputations, outcome-specific sequential selection weights, baseline-outcome adjustment, and measured sociodemographic, health, and movement-related covariates. Sensitivity analyses examined alternative adjustment and weighting specifications, outcome bounds, and nonlinear exposure-response relationships. Results: Approximately 3,820 participants contributed to each outcome analysis. The median long-bout accumulation proportion was 49.15% (interquartile range, 39.93%–58.21%). Per 10-percentage-point higher long-bout proportion, the fully adjusted mean difference was 0.426 points for Physical Functioning (95% confidence interval [CI], −0.096 to 0.948) and −0.099 points for pain burden (95% CI, −0.658 to 0.461). Models accounting for bounded outcome distributions produced similar estimates, and restricted cubic spline analyses showed no clear evidence of nonlinearity. Across comparable sensitivity analyses, estimates ranged from 0.138 to 0.504 points for Physical Functioning and from −0.158 to 0.079 points for pain burden. Conclusions: In this midlife cohort, a greater proportion of sitting/lying time accumulated in bouts lasting at least 30 minutes was not clearly associated with subsequent SF-36 Physical Functioning or pain burden after accounting for total sitting/lying time and measured covariates. Findings were broadly consistent across alternative model specifications and did not indicate a clear nonlinear association. These results do not establish causality or equivalence.

High-intensity interval training (HIIT) and exogenous ketone supplementation (EKS) have individually demonstrated potential in addressing overweight and obesity, particularly through their effects on appetite regulation and dietary behavior. However, the therapeutic potential of EKS in obesity management remains underexplored, and how it interacts with HIIT remains unclear. We hypothesize that combining HIIT and EKS may have a synergistic effect through "Neurocognitive-Behavioral Mechanisms". These mechanisms include direct effects on appetite-related brain pathways and indirect effects such as improvements in cognitive function that support healthier eating habits. Both HIIT and EKS may also increase levels of newly identified signaling compounds, such as lactate-phenylanine (Lac-Phe) and 3-(3-hydroxybutyrate (BHB)-Phe, which have been linked to reduced food intake in animal studies. Importantly, the shared pathways through which HIIT and ketones enhance cognitive function suggest that future obesity treatments could focus on optimizing brain and metabolic health, rather than relying solely on calorie restriction, to improve long-term adherence. Further research should clarify the neurocognitive and metabolic pathways involved and examine the long-term impact of combined HIIT and EKS interventions. This conceptual framework offers a novel perspective on how brain and behavior interact in obesity and may guide the development of innovative lifestyle strategies.

Low-carbohydrate time-restricted eating (LCTR) and sprint interval training (SIT) independently improve cardiometabolic health, but their combined effects on cardiac-specific biomarkers remain unknown. We investigated whether LCTR, with or without SIT, affects N-terminal pro-brain natriuretic peptide (NT-proBNP) and cardiac troponin T (cTnT) concentrations in young adults. Sixty-one young adults (31 males, 30 females) were randomized to a 4-week program of LCTR alone or LCTR + SIT. All participants consumed ≤ 10

This study explored the impact of circadian rhythms on the circulating cardiac troponin T (cTnT) response to a graded exercise test (GXT) and examined whether an initial GXT influenced the cTnT response to a subsequent GXT performed 7-9 days later. Twenty-one healthy young males (age: 20.6 ± 2.2 years, body mass index: 22.2 ± 2.6 kg/m2, V̇O2max: 31.8 ± 8.7 mL.kg-1.min-1) participated in three trials: an initial GXT (GXT1), a resting control trial (CON) and a second GXT (GXT2), separated by at least 72 h. The serum cTnT levels were measured pre-exercise, 4 h post-exercise or during the control. In GXT1, the cTnT levels did not show significant changes (median [range], pre: 3.80 [3.00-10.59] ng.L-1, post: 4.22 [3.00-9.08] ng.L-1, p > 0.05). During CON, the cTnT levels decreased significantly from morning to early afternoon (3.52 [3.00-10.84] vs. 3.00 [3.00-7.57] ng.L-1, p < 0.05), reflecting a circadian rhythm. Interestingly, GXT1 appeared to prevent this circadian decline. Furthermore, in GXT2, the cTnT levels significantly decreased post-exercise (4.13 [3.00-15.48] vs. 3.24 [3.00-12.96] ng.L-1, p < 0.05), suggesting a possible "late exercise preconditioning" effect from GXT1. These findings suggest that GXT can interact with circadian rhythms, altering cTnT dynamics, and that prior exercise may induce prolonged cardioprotective effects. This study highlights the importance of accounting for circadian variability and late preconditioning effects in future research on exercise-induced cTnT release.

Aim:Although reduced-exertion high-intensity interval training (REHIT) confers well-documented health benefits, most supporting evidence derives from laboratory studies that rely on specialized equipment. This study examined the real-world efficacy of equipment-free REHIT using burpees (BIT) in sedentary young adults. Methods:A 12-week randomized controlled trial (n = 319 inactive men, age 20.5 ± 1.1 years, maximal oxygen uptake [VO2max] 37.7 ± 1.4 ml/min/kg) compared four cohorts: supervised BIT (n = 79), unsupervised BIT in real-world conditions (BIT-RW; n = 79), supervised cycling-based sprint interval training (SIT; n = 82), and a non-exercising control (CON; n = 79). Exercise groups performed 2 × 20s all-out effort sessions 3-5 times weekly. Training and affective responses were monitored throughout the intervention. Pre- and post-intervention outcomes included body composition, cardiorespiratory fitness, and mental health (stress, depression, anxiety, sleep quality, resilience, and health-related quality of life [QoL]). Results:The supervised BIT achieved 91 %-94 % of maximal heart rate (HRmax), compared to ∼90 % HRmax in BIT-RW. All exercise groups exhibited significant physiological improvements: 6 %-8 % body mass reduction, 8 %-13 % VO2max increase (η 2 p = 0.7-0.8, p < 0.001). Additionally, exercise training resulted in significant reductions in stress (49-61 %, p < 0.001), anxiety (37-86 %, p < 0.001), depression (14-48 %, p < 0.001), as well as improvements in resilience (22-27 %, p < 0.001) and QoL (14-27 %, p < 0.001). Supervised BIT matched SIT in VO2max gains (5.0 ± 0.6 ml/min/kg), while BIT-RW showed smaller physiological benefits (3.0 ± 0.6 ml/min/kg) but 10 % greater improvements in affective responses (p < 0.05). Conclusions:This study demonstrates that a 40-s equipment-free REHIT protocol utilizing burpees improves both physical and mental health outcomes, even when implemented in unsupervised free-living settings. These findings suggest that BIT is an accessible and time-efficient training option for individuals constrained by limited access to equipment or professional oversight.

This study investigated the acute effects of ketone monoester on metabolic and neurocognitive indicators and underlying metabolism-brain-cognition interactions among young adults of healthy weight (HW) and those with overweight/obesity (OW). Forty participants were divided into two groups: HW (n = 20, age 23.80 +/- 3.96 years, body mass index (BMI) 21.49 +/- 1.80 kg/m(2)) and OW (n = 20, age 22.00 +/- 2.13 years, BMI 28.23 +/- 3.48 kg/m(2)). Each participant completed two trials (ketone monoester vs. placebo, 395 mg/kg dose) in a randomized order. Metabolic indicators (blood beta-hydroxybutyrate (BHB) and glucose) and neurocognitive function (causal density via functional near-infrared spectroscopy and cognitive interference via the Stroop task) were measured at baseline, 30 min, and 90 min post-supplementation. A chain mediation model was constructed to test the indirect effects of BHB level on cognitive interference through mediators like blood glucose and causal density. In the linear mixed models, significant effects were observed for trial (beta = -0.92, 0.20, -0.04, 25.53) and assessment time (beta = 0.50, -0.14, 0.09, -62.88) in BHB, glucose, causal density, and cognitive interference (p < 0.05), but not for group factors. Compared to OW, the effects of ketone monoester on prefrontal connectomes were more enduring in the HW (p < 0.05). Elevated BHB level improved cognitive function through decreasing glucose level and increasing causal density, with an estimate of -0.63. Acute ketone monoester supplementation elevated levels of blood BHB and prefrontal connectomes and decreased levels of glucose and cognitive interference, regardless of weight status. Elevated blood BHB enhanced cognitive function through multi-tiered neurometabolic pathways. Clinical trial registration: ClinicalTrials.gov (ID: NCT06368297).

Repeated-sprint training in hypoxia (RSH) has been shown to boost team-sport players' repeated-sprint ability (RSA). Whether players' global inspiratory muscle (IM) and core muscle (CM) functions would be altered concomitantly with RSH was not reported. This study was designed to compare the concomitant alternations in players' RSA and their IM and CM functions during a team-sport-specific intermittent exercise protocol (IEP) before and after the intervention. Twenty players were assigned into either RSH or control (CON) groups (n = 10 for each). RSH players participated in 5-wk RSH (15 sessions, 3 sets 5x5-s all-out treadmill sprints interspersed with 25-s passive recovery under the hypoxia of 13.5%) while CON players had no corresponding training. The changes in RSA between pre- and post-intervention, and the alterations in IM and CM functions that were revealed by maximum inspiratory mouth pressure (PImax) and sport-specific endurance plank test (SEPT) performance, respectively, between pre- and post-IEP and across pre- and post-intervention in the RSH group were compared with that of CON. Following the 5-wk RSH, players' RSA improved significantly (>6%, p < 0.05) while PImax and SEPT performance did not alter (P > 0.05). Nevertheless, PImax which declined markedly in pre-intervention IEP (pre-IEP 155.4 ± 22.7 vs post-IEP 140.6 ± 22.8 cmH2O, p < 0.05) was alleviated significantly in post-intervention IEP (152.2 ± 27.4 vs 152.6 ± 31.8, p > 0.05), while the concomitant declined SEPT performance in the pre-intervention IEP (155 ± 24.6 vs 98.1 ± 21.7 s, p < 0.05) was retained post intervention (170.7 ± 38.1 vs 100.5 ± 33.4, p < 0.05). For the CON, all variables were unchanged (p > 0.05). Such findings suggest that 5-wk RSH could enhance players' RSA but not global IM and CM functions. Nonetheless, the decline in PImax in pre-intervention IEP alleviated significantly post intervention led to a postulation that players' IM endurance, rather than strength, might improve with the 5-wk RSH regimen, while the possible improved IM endurance did not advance the fatigue resistance of CM.

Ratio-scaled VO2 is the widely used method for quantifying running economy (RE). However, this method should be criticized due to its theoretical defect and curvilinear relationship indicated by the allometric scaling, although no consensus has been achieved on the generally accepted exponent b value of body weight. Therefore, this study aimed to provide a quantitative synthesis of the reported exponents used to scale VO2 to body weight. Six electronic databases were searched based on related terms. Inclusion criteria involved human cardiopulmonary testing data, derived exponents, and reported precision statistics. The random-effects model was applied to statistically analyze exponent b. Subgroup and meta-regression analyses were conducted to explore the potential factors contributing to variation in b values. The probability of the true exponent being below 1 in future studies was calculated. The estimated b values were all below 1 and aligned with the 3/4 power law, except for the 95% prediction interval of the estimated fat-free body weight exponent b. A publication bias and a slightly greater I2 and τ statistic were also observed in the fat-free body weight study cohort. The estimated probabilities of the true body weight exponent, full body weight exponent, and fat-free body weight exponent being lower than 1 were 93.8% (likely), 95.1% (very likely), and 94.5% (likely) respectively. ‘Sex difference’, ‘age category’, ‘sporting background’, and ‘testing modality’ were four potential but critical variables that impacted exponent b. Overall, allometric-scaled RE should be measured by full body weight with exponent b raised to 3/4.

低心肺适能和久坐是心脏代谢疾病的独立风险因素.零食式锻炼(exercise snacks)是指分散在全天中反复进行单次小于1分钟的剧烈运动.作为一种新颖的运动锻炼策略,零食式锻炼既可提高心肺适能,同时又能打破久坐时间.与传统锻炼方式相比,零食式锻炼的突出特点是耗时极少且安排灵活.本文概述零食式锻炼的方法及其有益于心脏代谢健康的现有证据和未来研究方向.

Interval training protocols have gained popularity over the years, but their impact on appetite sensation compared to officially recommended training method, moderate intensity continuous training (MICT) is not well understood. Thus, this systematic review and meta-analysis aimed to compare a single session of high intensity interval training (HIIT) including sprint interval training (SIT) with MICT on appetite perception measured by the visual analog scale (VAS). After searching up articles published up to September 2021, 13 randomized controlled studies were included in the meta-analysis. Outcomes of meta-analysis demonstrated that both acute sessions of HIIT/SIT and MICT suppressed appetite compared to no-exercise control groups immediately post exercise but there were no significant effects 30-90 min post exercise or in AUC values, indicating a transient effect of exercise on appetite sensations. Moreover, differences in appetite sensations between HIIT/SIT and MICT were negligible immediately post exercise, but HIIT/SIT suppressed hunger (MD = -6.347 [-12.054, -0.639], p = 0.029) to a greater extent than MICT 30-to 90-min post exercise, while there was a lack of con-sistency other VAS subscales of appetite. More studies that address the impact of exercising timing, nutrient compositions of energy intake (energy intake (EI)) and differences in participants' characteristics and long-term studies analyzing chronic effects are needed to comprehensively examine the differences between HIIT/SIT and MICT on appetite and EI. Systematic Review Registration: [https://www.crd.york.ac.uk/PROSPERO], Identifier [CRD42021284898].

Background: Enhancement in maximal oxygen consumption (VO2max) induced by hypoxic training is important for both athletes and non-athletes. However, the lack of comparison of multiple paradigms and the exploration of related modulating factors leads to the inability to recommend the optimal regimen in different situations. This study aimed to investigate the efficacy of seven common hypoxic training paradigms on VO2max and associated moderators. Methods: Electronic (i.e., five databases) and manual searches were performed, and 42 studies involving 1246 healthy adults were included. Pairwise meta-analyses were conducted to compare different hypoxic training paradigms and hypoxic training and control conditions. The Bayesian network meta-analysis model was applied to calculate the standardised mean differences (SMDs) of pre-post VO2max alteration among hypoxic training paradigms in overall, athlete, and non-athlete populations, while meta-regression analyses were employed to explore the relationships between covariates and SMDs. Results: All seven hypoxic training paradigms were effective to varying degrees, with SMDs ranging from 1.45 to 7.10. Intermittent hypoxia interval training (IHIT) had the highest probability of being the most efficient hypoxic training paradigm in the overall population and athlete subgroup (42%, 44%), whereas intermittent hypoxic training (IHT) was the most promising hypoxic training paradigm among non-athletes (66%). Meta-regression analysis revealed that saturation hours (coefficient, 0.004; P = 0.038; 95% CI [0.0002, 0.0085]) accounted for variations of VO2max improvement induced by IHT. Conclusion: Efficient hypoxic training paradigms for VO2max gains differed between athletes and non-athletes, with IHIT ranking best for athletes and IHT for non-athletes. The practicability of saturation hours is confirmed with respect to dose-response issues in the future hypoxic training and associated scientific research. Registration: This study was registered in the PROSPERO international prospective register of systematic reviews (CRD42022333548).

Background: Exercise intensity has been suggested to influence acute appetite-regulating gut hormone responses after exercise. High intensity interval training (HIIT) with near maximal to maximal intensity or sprint interval training (SIT) with supramaximal intensity might induce greater effects on gut hormones compared to moderate intensity continuous training (MICT), while current findings were inconsistent regarding the effects of these popular training methods. Objective: This systematic review and meta-analysis aimed to synthesis the findings in the literature and explore the impact of exercise modality on acylated ghrelin (AG), glucagon-like peptide-1 (GLP-1) and peptide YY (PYY). Methods: After searching the major databases (PubMed, Web of science and ScienceDirect, Scopus, Cochrane Library) to find articles published up to May 2022, twelve studies that compared hormone responses to HIIT/SIT and MICT were identified and included in the analysis. Results: A random-effects meta-analysis showed that HIIT/SIT and MICT decreased AG concentration and increased GLP-1 and PYY concentration compared with no exercise control group, while interval training protocols, especially SIT protocols, elicited greater effect sizes in suppressing AG levels at all of the analysed time points and PYY immediately post-exercise compared to MICT. Conclusion: Acute SIT with lower exercise volume appears to be a more advantageous approach to decrease plasma AG concentration and potentially suppress hunger to a greater extent compared to MICT, despite the similar effects of HIIT/SIT compared to MICT in increasing anorectic hormones (i.e., GLP-1 and PYY). Future studies are needed to further investigate the impact of moderators (e.g., gender, body composition and exercise mode) on the variability of changes in gut hormones after interval trainings.

BACKGROUND:Effects of ketone supplements as well as relevant dose-response relationships and time effects on blood β-hydroxybutyrate (BHB), glucose and insulin are controversial. OBJECTIVE:This study aimed to summarize the existing evidence and synthesize the results, and demonstrate underlying dose-response relationships as well as sustained time effects. METHODS:Medline, Web of Science, Embase, and Cochrane Central Register of Controlled Trials were searched for relevant randomized crossover/parallel studies published until 25th November 2022. Three-level meta-analysis compared the acute effects of exogenous ketone supplementation and placebo in regulating blood parameters, with Hedge's g used as measure of effect size. Effects of potential moderators were explored through multilevel regression models. Dose-response and time-effect models were established via fractional polynomial regression. RESULTS:The meta-analysis with 327 data points from 30 studies (408 participants) indicated that exogenous ketones led to a significant increase in blood BHB (Hedge's g = 1.4994, 95% CI [1.2648, 1.7340]), reduction in glucose (Hedge's g = -0.3796, 95% CI [-0.4550, -0.3041]), and elevation in insulin of non-athlete healthy population (Hedge's g = 0.1214, 95%CI [0.0582, 0.3011]), as well as insignificant change in insulin of obesity and prediabetes. Nonlinear dose-response relationship between ketone dosage and blood parameter change was observed in some time intervals for BHB (30-60 min; >120 min) and insulin (30-60 min; 90-120 min), with linear relationship observed for glucose (>120 min). Nonlinear associations between time and blood parameter change were found in BHB (>550 mg/kg) and glucose (450-550 mg/kg), with linear relationship observed in BHB (≤250 mg/kg) and insulin (350-550 mg/kg). CONCLUSION:Dose-response relationships and sustained time effects were observed in BHB, glucose and insulin following ketone supplementation. Glucose-lowering effect without increasing insulin load among population of obesity and prediabetes was of remarkable clinical implication. REGISTRY AND REGISTRY NUMBER:PROSPERO (CRD42022360620).

To investigate (1) the boosting effects immediately and 4 weeks following 2-week, 6-session repeated-sprint training in hypoxia (RSH2-wk, n = 10) on the ability of team-sport players in performing repeated sprints (RSA) during a team-sport-specific intermittent exercise protocol (RSAIEP) by comparing with normoxic counterpart (CON2-wk, n = 12), and (2) the dose effects of the RSH by comparing the RSA alterations in RSH2-wk with those resulting from a 5-week, 15-session regimen (RSH5-wk, n = 10). Repeated-sprint training protocol consisted of 3 sets, 5 × 5-s all-out sprints on non-motorized treadmill interspersed with 25-s passive recovery under the hypoxia of 13.5 In comparison with pre-intervention, RSA variables, particularly the mean velocity, horizontal force, and power output during the RSAIEP enhanced significantly immediate post RSH in RSH2-wk (5.1–13.7

BACKGROUND:Physical activity (PA) surveillance, policy, and research efforts need to be periodically appraised to gain insight into national and global capacities for PA promotion. The aim of this paper was to assess the status and trends in PA surveillance, policy, and research in 164 countries. METHODS:We used data from the Global Observatory for Physical Activity (GoPA!) 2015 and 2020 surveys. Comprehensive searches were performed for each country to determine the level of development of their PA surveillance, policy, and research, and the findings were verified by the GoPA! Country Contacts. Trends were analyzed based on the data available for both survey years. RESULTS:The global 5-year progress in all 3 indicators was modest, with most countries either improving or staying at the same level. PA surveillance, policy, and research improved or remained at a high level in 48.1%, 40.6%, and 42.1% of the countries, respectively. PA surveillance, policy, and research scores decreased or remained at a low level in 8.3%, 15.8%, and 28.6% of the countries, respectively. The highest capacity for PA promotion was found in Europe, the lowest in Africa and low- and lower-middle-income countries. Although a large percentage of the world's population benefit from at least some PA policy, surveillance, and research efforts in their countries, 49.6 million people are without PA surveillance, 629.4 million people are without PA policy, and 108.7 million live in countries without any PA research output. A total of 6.3 billion people or 88.2% of the world's population live in countries where PA promotion capacity should be significantly improved. CONCLUSION:Despite PA is essential for health, there are large inequalities between countries and world regions in their capacity to promote PA. Coordinated efforts are needed to reduce the inequalities and improve the global capacity for PA promotion.

Background/Objectives The purpose of this study was to investigate the effects of repeated sprint interval training (RSIT) under different hypoxic conditions in comparison with normoxic RSIT on cardiorespiratory fitness (CRF) and metabolic health in sedentary young women. Methods Sixty-two sedentary young women (age: 21.9 ± 2.8 years, peak oxygen uptake [V̇O2peak] 25.9 ± 4.5 ml kg−1·min−1) were randomized into one of the four groups, including a normoxic RSIT group (N), RSIT simulating an altitude of 2500 m (H2500), RSIT simulating an incremental altitude of 2500–3400 m (H2500–3400) and a non-exercise control group (C). The training intervention (80 × 6 s all-out cycling sprints with 9 s recovery) was performed three times/week for 4 weeks. Anthropometric measures, V̇O2peak, fasting blood glucose and lipids were assessed during the follicular phase of the menstrual cycle before and after the intervention. Results Compared with the control group, significant increases in V̇O2peak were found in both hypoxic groups (H2500: +8.2%, p < 0.001, d = 0.52; H2500-3400: +10.9%, p < 0.05, d = 0.99) but not in the N group (+3.6%, p > 0.05, d = 0.21) after the intervention, whereas the two hypoxic groups had no difference in V̇O2peak. Blood glucose and lipids, and body composition remained unchanged in all groups. Conclusion The present study indicates that combining hypoxia with RSIT can enhance the improvement of CRF compared with normoxic RSIT alone in the sedentary young population. Yet, compared with RSIT under stable hypoxia, incremental hypoxia stress in the short-term does not additionally ameliorate CRF.

This study examined the alterations of heart rate variability (HRV) following iso-duration resistance (RES) and sprint-interval exercises (SIE) by comparing with that of non-exercise control (CON) in 14 non-obese (NOB) and 15 obese (OB) young men. Time and frequency domain measures as well as nonlinear metrics of HRV were assessed before and immediately after exercise, and during every 20 min until 120 min post-exercise. The variables during the first 4 h of actual sleep time at night, and the period of 12–14 h post-exercise were also measured. All trials were scheduled at 20:00. It was found that RES and SIE attenuated the HRV in both NOB and OB (P < 0.05), and the attenuated HRV restored progressively during subsequent recovery. Although the changes in HRV indices among various time points during the recovery period and its interaction across RES, SIE, and CON were not different between NOB and OB, the restoration of the declined HRV indices to corresponding CON level in the 2 exercise trials in OB appeared to be sluggish in relative to NOB. Notwithstanding, post-exercise HRV that recorded during actual sleep at night and during 12–14 h apart from exercise were unvaried among the 3 trials in both groups (P > 0.05). These findings suggest that obesity is likely to be a factor hindering the removal of exercise-induced cardiac autonomic disturbance in young men. Nonetheless, the declined HRV following both the RES and SIE protocols was well restored after a resting period of ∼10 h regardless of obesity. The study was registered at ISRCTN as https://doi.org/10.1186/ISRCTN88544091.

Abstract The purpose of this study was to determine whether exercise training mediated cardiac troponin T (cTnT) and whether this was associated with increases in left ventricular mass (LVM). Fifty-four sedentary obese women were randomised to high-intensity interval training (HIIT, repeated 4–min cycling at 90% V̇O2max interspersed with 3–min rest), work-equivalent continuous aerobic training (CAT, continuous cycling at 60% V̇O2max) or a control group (CON). Resting serum cTnT was assessed using a high-sensitivity assay before and after 12 weeks of training. LVM was determined from 2D echocardiography at the same timepoints. Both HIIT and CAT induced a similar elevation (median 3.07 to 3.76 ng.l−1, p<0.05) in resting cTnT compared with pre-training and the CON (3.49 to 3.45 ng.l−1, p>0.05). LVM index in HIIT increased (62.2±7.8 to 73.1±14.1 g.m−2, p<0.05), but not in CAT (66.1±9.7 to 67.6±9.6 g.m−2, p>0.05) and CON (67.9±9.5 to 70.2±9.1 g.m−2, p>0.05). Training-induced changes in resting cTnT did not correlate with changes in LVM index (r=−0.025, p=0.857). These findings suggest that twelve weeks of either HIIT or CAT increased resting cTnT, but the effects were independent of any changes in LVM in sedentary obese women.