Repeated-sprint training in hypoxia boosts up team-sport-specific repeated-sprint ability: 2-week vs 5-week training regimen.

PURPOSE: 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). METHODS: 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% and normoxia, respectively. The within- (pre-, post-, 4-week post-intervention) and between- (RSH2-wk, RSH5-wk, CON2-wk) group differences in the performance of four sets of RSA tests held during the RSAIEP on the same treadmill were assessed. RESULTS: 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%), while trivially in CON2-wk (2.1-6.2%). Nevertheless, the enhanced RSA in RSH2-wk diminished 4 weeks after the RSH (- 3.17-0.37%). For the RSH5-wk, the enhancement of RSA immediately following the 5-week RSH (4.2-16.3%) did not differ from that of RSH2-wk, yet the enhanced RSA was well-maintained 4-week post-RSH (0.12-1.14%). CONCLUSIONS: Two-week and five-week RSH regimens could comparably boost up the effects of repeated-sprint training in normoxia, while dose effect detected on the RSA enhancement was minimal. Nevertheless, superior residual effects of the RSH on RSA appear to be associated with prolonged regimen.

Acute effect of high-intensity interval training versus moderate-intensity continuous training on appetite perception: A systematic review and meta-analysis.

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 consistency 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].

Comparative efficacy of various hypoxic training paradigms on maximal oxygen consumption: A systematic review and network meta-analysis.

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).

Exercise Training Increases Serum Cardiac Troponin T Independent of Left Ventricular Mass.

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.

Hypoxic repeated sprint interval training improves cardiorespiratory fitness in sedentary young women.

OBJECTIVE: 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.

Exercise training-induced visceral fat loss in obese women: The role of training intensity and modality.

Visceral fat loss in response to four-cycle ergometer training regimens with explicit differences in exercise intensity and modality was compared. Fifty-nine obese young women (body fat percentage ≥ 30%) were randomized to a 12-week intervention consisting of either all-out sprint interval training (SITall-out , n = 11); supramaximal SIT (SIT120 , 120% V ˙ O2peak , n = 12); high-intensity interval training (HIIT90 , 90% V ˙ O2peak , n = 12), moderate-intensity continuous training (MICT, 60% V ˙ O2peak , n = 11), or no training (CON, n = 13). The total work done per training session in SIT120 , HIIT90 , and MICT was confined to 200 kJ, while it was deliberately lower in SITall-out . The abdominal visceral fat area (AVFA) was measured through computed tomography scans. The whole-body and regional fat mass were assessed through dual-energy X-ray absorptiometry. Pre-, post-, and 3-hour post-exercise serum growth hormone (GH), and epinephrine (EPI) were measured during selected training sessions. Following the intervention, similar reductions in whole-body and regional fat mass were found in all intervention groups, while the reductions in AVFA resulting from SITall-out , SIT120 , and HIIT90 (>15 cm2 ) were greater in comparison with MICT (<3.5 cm2 , P < .05). The AVFA reductions among the SITs and HIIT groups were similar, and it was concomitant with the similar exercise-induced releases of serum GH and EPI. CON variables were unchanged. These findings suggest that visceral fat loss induced by interval training at or above 90% V ˙ O2peak appeared unresponsive to the change in training intensity. Nonetheless, SITall-out is still the most time-efficient strategy among the four exercise-training regimes for controlling visceral obesity.

Interval training causes the same exercise enjoyment as moderate-intensity training to improve cardiorespiratory fitness and body composition in young Chinese women with elevated BMI.

This study examined the effects of 12 weeks of sprint interval training (SIT), high-intensity interval training (HIIT) and moderate-intensity continuous training (MICT) on cardiorespiratory fitness (peak oxygen uptake, VO2peak), body composition and physical activity enjoyment in overweight young women. Sixty-six participants (age 21.2 ± 1.4 years, body mass index (BMI) 26.0 ± 3.0 kg·m-2, body fat percentage 39.0 ± 2.8%) were randomly assigned to non-exercise control (CON), thrice-weekly SIT (80 × 6 s "all-out" cycling interspersed with 9 s rest), and HIIT (4 min cycling at 90% VO2peak followed with 3 min recovery for ~ 60 min) or MICT (~ 65 min continuous cycling at 60% VO2peak) with equivalent mechanical work (200/300 KJ). Compared to the CON group, all three training groups had significant and similar improvements in VO2peak (~ +20%, d = 2.5-3.4), fat mass (~ -10%, d = 1.3-2.1) and body fat percentage (~ -5%, d = 1.0-1.1) after a 12-week intervention. Similar high levels of enjoyment were observed among groups for most (~70%) of the training sessions. The findings suggest that the three training regimes are equally enjoyable and could result in similar improvements in cardiorespiratory fitness and body composition in overweight/obese young women, but SIT is a more time-efficient strategy.

Twelve weeks of low volume sprint interval training improves cardio-metabolic health outcomes in overweight females.

This study compared the effects of 12-week sprint interval training (SIT), high-intensity interval training (HIIT), and moderate-intensity continuous training (MICT) on cardiorespiratory fitness (V̇O2peak), body mass and insulin sensitivity in overweight females. Forty-two overweight women (age 21.2 ± 1.4 years, BMI 26.3 ± 2.5 kg·m-2) were randomized to the groups of SIT (80 × 6-s sprints + 9-s rest), and isoenergetic (300KJ) HIIT (~9 × 4-min cycling at 90% V̇O2peak + 3-min rest) and MICT (cycling at 60% V̇O2peak for ~ 61-min). Training intervention was performed 3 d·week-1 for 12 weeks. After intervention, all three groups induced the same improvement in V̇O2peak (~ +25%, p < 0.001) and a similar reduction in body mass (~ - 5%, p < 0.001). Insulin sensitivity and fasting insulin levels were improved significantly on post-training measures in SIT and HIIT by ~26% and ~39% (p < 0.01), respectively, but remain unchanged in MICT. In contrast, fasting glucose levels were only reduced with MICT (p < 0.01). The three training strategies are equally effective in improving V̇O2peak and reducing body mass, however, the SIT is time-efficient. High-intensity training (i.e. SIT and HIIT) seems to be more beneficial than MICT in improving insulin sensitivity. Abbreviations: BMI: body mass index; CVD: cardiovascular disease; HIEG: hyperinsulinaemic euglycaemic glucose; HIIT: high-intensity interval training; HOMA-IR: homeostasis model assessment of insulin resistance; HR: heart rate; MICT: moderate-intensity continuous training; RPE: ratings of perceived exertion; SIT: sprint interval training; T2D: type 2 diabetes; V̇O2peak: peak oxygen consumption.

The Effects of High-Intensity Interval Exercise and Hypoxia on Cognition in Sedentary Young Adults.

Background and Objectives: Limited research has evaluated the effects of acute exercise on cognition under different conditions of inspired oxygenation. Thus, the purpose of this study was to examine the effects of high-intensity interval exercise (HIE) under normoxia (inspired fraction of oxygen (FIO2): 0.209) and moderate hypoxia (FIO2: 0.154) on cognitive function. Design: A single-blinded cross-over design was used to observe the main effects of exercise and oxygen level, and interaction effects on cognitive task performance. Methods: Twenty inactive adults (10 males and 10 females, 19⁻27 years old) performed a cognitive task (i.e., the Go/No-Go task) before and immediately after an acute bout of HIE under normoxic and hypoxic conditions. The HIE comprised 10 repetitions of 6 s high-intensity cycling against 7.5% body weight interspersed with 30 s passive recovery. Heart rate, peripheral oxygen saturation (SpO2) and rating of perceived exertion were monitored. Results: The acute bout of HIE did not affect the reaction time (p = 0.204, η² = 0.083) but the accuracy rate decreased significantly after HIE under both normoxic and hypoxic conditions (p = 0.001, η² = 0.467). Moreover, moderate hypoxia had no influence either on reaction time (p = 0.782, η² = 0.004) or response accuracy (p = 0.972, η² < 0.001). Conclusions: These results indicate that an acute session of HIE may impair response accuracy immediately post-HIE, without sacrificing reaction time. Meanwhile moderate hypoxia was found to have no adverse effect on cognitive function in inactive young adults, at least in the present study.

Impact of high-intensity interval training and moderate-intensity continuous training on resting and postexercise cardiac troponin T concentration.

NEW FINDINGS: What is the central question of this study? Does exercise training impact resting and postexercise cardiac troponin T (cTnT) concentration? What is the main finding and its importance? This randomized controlled intervention study demonstrated that 12 weeks of either high-intensity interval training or moderate-intensity continuous training largely abolished the exercise-induced elevation in cTnT when exercise was performed at the same absolute intensity. There was no impact of training on resting cTnT or postexercise appearance of cTnT when exercise was performed at the same relative intensity. These findings provide new information that might help clinicians with decision-making in relationship to basal and postexercise values of cTnT in individuals with different training status. ABSTRACT: We evaluated the influence of 12 weeks of high-intensity interval training [HIIT; repeated 4 min cycling at 90% of maximal oxygen uptake (V̇O2max) interspersed with 3 min rest, 200-300 kJ per session, 3 or 4 days each week] and work-equivalent moderate-intensity continuous training (MICT; continuous cycling at 60% V̇O2max) on resting cardiac troponin T (cTnT) and the appearance of exercise-induced cTnT. Forty-eight sedentary obese young women were randomly assigned to HIIT, MICT or a control group. The V̇O2max and body composition were measured before and after training. At baseline, cTnT was assessed using a high-sensitivity assay at rest and immediately, 2 and 4 h after 45 min cycling at 60% V̇O2max. After a 12 week training period, cTnT was assessed before and after 45 min cycling at the same relative and absolute intensities as before training. Training led to higher V̇O2max and lower fat mass in both HIIT and MICT groups (all P < 0.05). Before training, cTnT was significantly elevated in all three groups (by 35-118%, all P < 0.05) with acute exercise. After training, both resting and postexercise cTnT concentrations (same relative intensity) were similar to pretraining values. In contrast, postexercise cTnT (same absolute intensity, which represented a smaller exercise stimulus) was not elevated from rest in both HIIT and MICT groups. In conclusion, 12 weeks of either HIIT or MICT largely abolished the postexercise elevation of cTnT concentration when exercise was performed at the same absolute intensity. There was, however, no impact of training on resting cTnT or postexercise appearance of cTnT for exercise performed at the same relative intensity.

Influence of recovery duration during 6-s sprint interval exercise on time spent at high rates of oxygen uptake.

BACKGROUND/OBJECTIVE: This study examined whether time spent at high rates of oxygen consumption (VO2) during 6-s sprint interval exercises (SIE) is a function of recovery interval duration. METHODS: In a randomised crossover study, thirteen male endurance runners performed 40 × 6-s all-out sprints interspersed with 15-s, 30-s and 60-s passive recovery intervals (SIE15, SIE30, and SIE60 trials respectively), and a work duration-matched Wingate-SIE (8 × 30-s all-out sprints with 4-min passive recovery, SIEWin trial). The accumulated exercise time at ≥ 80%, 85%, 90%, 95% and 100% of VO2max, and maximum heart rate (HRmax) in the four trials were compared. RESULTS: During the 6-s SIEs, accumulated time spent at all selected high rates of VO2max increased as recovery time decreased, whilst the SIE work rate decreased (p < .05). In SIEWin, although the exercise lasted longer, the time spent at ≥90% VO2max (74 ±â€¯16 s) was significant less than that in SIE15 (368 ±â€¯63 s, p < .05), yet comparable to that in SIE30 (118 ±â€¯30 s, p > .05), and longer than that in SIE60 (20 ±â€¯14 s, p < .05). The differences between the four trials in accumulated time at high percentages of HRmax were similar to those for VO2, although the temporal characteristics of the increases in HR and VO2 during the SIEs were different. CONCLUSION: In conclusion, the duration of the recovery interval in 6-s SIE protocols appears to be a crucial parameter when sprint interval training is prescribed to enhance aerobic capacity. Further, the SIE15 protocol may represent a potential alternative to 30-s SIEWin in the development of time-efficient aerobic training intervention.

Sex differences in release of cardiac troponin T after endurance exercise.

CONTEXT: Post-exercise cardiac troponin release has been extensively described in athletic groups but little attention has been given to any role of sex in mediating this phenomenon. OBJECTIVE: We compared the release of cardiac troponin T (cTnT) after endurance running in training-experience, biological-age and maturity-matched young male and female runners. MATERIALS AND METHODS: Nineteen male (training history: 2.3 ± 1.0 years; mean age: 16.1 ± 1.2 years; Tanner stage: 3.7 ± 0.6) and 19 female (training history: 2.2 ± 1.0 years; mean age: 15.9 ± 1.4 years; Tanner stage: 4.0 ± 0.4) runners performed a 21 km run with "all-out" effort. Serum cTnT levels were assessed at pre-exercise (Pre-ex) and at 4 h post-exercise (Post-ex). RESULTS: At Pre-ex, cTnT concentrations were below the 99th percentile value (10 ng.l-1) in 32/38 runners. Post-ex cTnT increased in all subjects but the response was substantially higher (p < 0.05) in males [median (range): 210 (20-1360) ng.l-1] than females [median (range): 80 (10-550) ng.l-1]. At Post-ex, 95% (95% confidence interval: 75-99%) of males and 63% (95% confidence interval: 41-81%) of females (p < 0.05) had cTnT concentrations above the cut-off for acute myocardial infarction. CONCLUSIONS: The present data suggest that post-exercise cTnT elevation occurs in all runners but is augmented in young male compared to female athletes.

The influence of basketball dribbling on repeated high-intensity intermittent runs.

BACKGROUND/OBJECTIVE: This research examines whether or not the Yo-Yo testing performance could reflect the repeatability of high-intensity intermittent dribbling in adolescent basketball players. METHODS: Thirty-six teenage basketball players aged 13-18 years were invited to participate in this study. RESULTS: A test-retest showed that the Yo-Yo intermittent endurance Level 2 (IE2) test with dribbling (intraclass correlation coefficient = 0.92; coefficient of variation = 12.6%; d = 0.24) and without dribbling (intraclass correlation coefficient = 0.83; coefficient of variation = 15.0%; d = 0.37) had acceptable reliability. The dribbling distance covered was significantly shorter than was the running performance of the Yo-Yo IE2 test in participants younger than 15 years (junior; 1138 ± 417 m vs. 910 ± 299 m, p < 0.01; d = 0.65), as well as in the entire study sample (1077 ± 398 m vs. 1267 ± 437 m, p < 0.05; d = 0.45), whereas there was no significant difference in the senior players between the two protocols (1396 ± 436 m vs. 1244 ± 427 m, p > 0.05; d = 0.35). Moderate to large correlations were found between running and dribbling performances in the senior sample (r = 0.57, p = 0.06), the junior sample (r = 0.87, p < 0.01), and the whole (r = 0.72, p < 0.01) sample, respectively. CONCLUSION: The results suggest that the Yo-Yo IE2 test could reflect the repeatability of high-intensity intermittent basketball dribbling performance, while dribbling skills may have different influences on high-intensity intermittent exercise capacity in adolescent players at different ages.

Acute effect of high-intensity interval training versus moderate-intensity continuous training on appetite-regulating gut hormones in healthy adults: A systematic review and meta-analysis.

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.

Bilateral motor cortex functional differences in left-handed approaching-avoiding behavior.

Automatic action tendencies occur at behavioral and neurophysiological levels during task performance with the dominant right hand, with shorter reaction times (RTs) and higher excitability of the contralateral primary motor cortex (M1) during automatic vs. regulated behavior. However, effects associated with the non-dominant left-hand in approaching-avoiding behavior remain unclear. Here, we used transcranial magnetic stimulation during the performance by 18 participants of an approaching-avoiding task using the non-dominant left hand. Single-pulse transcranial magnetic stimulation was applied over left or right M1 at 150 and 300 ms after the onset of an emotional stimulus. RTs and motor-evoked potentials (MEPs) were recorded. Significant automatic action tendencies were observed at the behavioral level. Higher MEP amplitudes were detected 150 ms after stimulus onset from the right hand (non-task hand, corresponding to left M1) during regulated behavior compared with during automatic behavior. However, no significant modulation was found for MEP amplitudes from the left hand (task hand, corresponding to right M1). These findings suggested that left M1 may play a principal role in the early phase of mediating left-handed movement toward an emotional stimulus.

Effects of ketone supplements on blood ß-hydroxybutyrate, glucose and insulin: A systematic review and three-level meta-analysis.

BACKGROUND: Effects of ketone supplements as well as relevant dose-response relationships and time effects on blood ß-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).

Sprint Interval Exercise Improves Cognitive Performance Unrelated to Postprandial Glucose Fluctuations at Different Levels of Normobaric Hypoxia.

Objective: The aim of our study was to examine cognition response to sprint interval exercise (SIE) against different levels of hypoxia. Research design and methods: 26 recreational active males performed SIE (20 × 6 s of all-out cycling bouts, 15 s of passive recovery) under normoxia (FIO2: 0.209), moderate hypoxia (FIO2: 0.154), and severe hypoxia (FIO2: 0.112) in a single-blinded crossover design. Cognitive function and blood glucose were assessed before and after 0, 10, 30, and 60 min of the SIE. Heart rate (HR), peripheral oxygen saturation (SpO2), and ratings of perceived exertion (RPE, the Borg 6−20-point scale) during each SIE trial were recorded before and immediately after every five cycling bouts, and after 0, 10, 30, and 60 min of the SIE. Results: All the three SIE trials had a significantly faster overall reaction time in the Stroop test at 10 min after exercise as compared to that of the baseline value (p = 0.003, ƞ2 = 0.606), and returned to normal after 60 min. The congruent RT at 10 min after SIE was significantly shorter than that of the baseline (p < 0.05, ƞ2 = 0.633), while the incongruent RT at both 10 min and 30 min were significantly shorter than that measured at baseline (p < 0.05, ƞ2 = 0.633). No significant differences in terms of accuracy were found across the three trials at any time points (p = 0.446, ƞ2 = 0.415). Blood glucose was significantly reduced at 10 min and was sustained for at least 60 min after SIE when compared to pre-exercise in all trials (p < 0.05). Conclusions: Acute SIE improved cognitive function regardless of oxygen conditions, and the sustained improvement following SIE could last for at least 10−30 min and was unaffected by the altered blood glucose level.

Comparative Effectiveness of Multiple Exercise Interventions in the Treatment of Mental Health Disorders: A Systematic Review and Network Meta-Analysis.

BACKGROUND: The efficacy of exercise interventions in the treatment of mental health disorders is well known, but research is lacking on the most efficient exercise type for specific mental health disorders. OBJECTIVE: The present study aimed to compare and rank the effectiveness of various exercise types in the treatment of mental health disorders. METHODS: The PubMed, Web of Science, PsycINFO, SPORTDiscus, CINAHL databases, and the Cochrane Central Register of Controlled Trials as well as Google Scholar were searched up to December 2021. We performed pairwise and network meta-analyses as well as meta-regression analyses for mental health disorders in general and each type of mental health disorder, with alterations in symptom severity as the primary outcome. RESULTS: A total of 6456 participants from 117 randomized controlled trials were surveyed. The multimodal exercise (71%) had the highest probability of being the most efficient exercise for relieving depressive symptoms. While resistance exercise (60%) was more likely to be the most effective treatment for anxiety disorder, patients with post-traumatic stress disorder (PTSD) benefited more from mind-body exercise (52%). Furthermore, resistance exercise (31%) and multimodal exercise (37%) had more beneficial effects in the treatment of the positive and negative symptoms of schizophrenia, respectively. The length of intervention and exercise frequency independently moderated the effects of mind-body exercise on depressive (coefficient = 0.14, p = .03) and negative schizophrenia (coefficient = 0.96, p = .04) symptoms. CONCLUSION: Multimodal exercise ranked best for treating depressive and negative schizophrenic symptoms, while resistance exercise seemed to be more beneficial for those with anxiety-related and positive schizophrenic symptoms. Mind-body exercise was recommended as the most promising exercise type in the treatment of PTSD. However, the findings should be treated with caution due to potential risk of bias in at least one dimension of assessment and low-to-moderate certainty of evidence. Trial Registration This systematic review was registered in the PROSPERO international prospective register of systematic reviews (CRD42022310237).

Effects of Low-Carbohydrate Diet and Exercise Training on Gut Microbiota.

Objective: This study was aimed to evaluate the effects of low-carbohydrate diet (LC) and incorporated high-intensity interval training (HIIT) or moderate-intensity continuous training (MICT) on gut microbiota, and the associations between changes in gut microbiota and cardiometabolic health-related profiles. Methods: Fifty overweight/obese Chinese females (age 22.2 ± 3.3 years, body mass index 25.1 ± 3.1 kg/m-2) were randomized to the groups of LC, LC and HIIT (LC-HIIT, 10 repetitions of 6-s sprints and 9-s rest), and LC and MICT group (LC-MICT, cycling at 50-60% V̇O2peak for 30 min). The LC-HIIT and LC-MICT experienced 20 training sessions over 4 weeks. Results: The 4-week LC intervention with/without additional training failed to change the Shannon, Chao 1, and Simpson indexes (p > 0.05), LC increased Phascolarctobacterium genus, and LC-HIIT reduced Bifidobacterium genus after intervention (p < 0.05). Groups with extra exercise training increased short-chain fatty acid-producing Blautia genus (p < 0.05) and reduced type 2 diabetes-related genus Alistipes (p < 0.05) compared to LC. Sutterella (r = -0.335) and Enterobacter (r = 0.334) were associated with changes in body composition (p < 0.05). Changes in Ruminococcus, Eubacterium, and Roseburia genera were positively associated with blood pressure (BP) changes (r = 0.392-0.445, p < 0.05), whereas the changes in Bacteroides, Faecalibacterium, and Parabacteroides genera were negatively associated with BP changes (r = -0.567 to -0.362, p < 0.05). Conclusion: LC intervention did not change the α-diversity and overall structure of gut microbiota. Combining LC with exercise training may have additional benefits on gut physiology. Specific microbial genera were associated with LC- and exercise-induced regulation of cardiometabolic health.

Cardiac autonomic disturbance following resistance and sprint-interval exercises in non-obese and obese young men.

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.