High-intensity interval training and cardiorespiratory fitness in adults: An umbrella review of systematic reviews and meta-analyses.

BACKGROUND: High-intensity interval training (HIIT) is characterized by repeated bouts of relatively intense exercise interspersed with recovery periods. Previous studies have evaluated this exercise strategy with various population subgroups, regimens, and comparator groups, limiting the generalizability of findings. We performed a novel umbrella review to generate an up-to-date synthesis of the available evidence regarding the effect of HIIT on cardiorespiratory fitness (CRF) in adults as compared to non-exercise control and traditional continuous forms of exercise such as moderate-intensity continuous training (MICT). METHODS: An umbrella review was conducted in accordance with the Preferred Reporting Items for Overviews of Reviews guideline. Seven databases (MEDLINE, EMBASE, Cochrane Database, CINAHL, Scopus, SPORTDiscus, and Web of Science) were searched until February 2024. Systematic reviews with meta-analyses comparing HIIT and active/non-active control conditions were included. Literature search, data extraction, and methodological quality assessment (AMSTAR-2) were conducted independently by two reviewers. RESULTS: Twenty-four systematic reviews with meta-analyses, representing 429 primary studies and 12 967 unique participants, met the inclusion criteria. Most of the systematic reviews received moderate-to-critically low AMSTAR-2 scores. The data showed that HIIT, including the particularly intense variant "sprint interval training" (SIT), significantly increases CRF in adults compared to non-exercise control (standardized mean difference [SMD]: 0.28 to 4.31; weighted mean difference [WMD]: 3.25 to 5.5 mL/kg/min) and MICT (SMD: 0.18 to 0.99; WMD: 0.52 to 3.76 mL/kg/min). This effect was consistently observed across specific groups of individuals (e.g., apparently healthy adults, individuals with overweight/obesity, older adults, and high-level athletes) and HIIT modalities (e.g., low-volume HIIT, whole-body HIIT, home-based HIIT, aquatic HIIT, and short SIT). CONCLUSION: Existing evidence from systematic reviews consistently supports the effect of HIIT on enhancing CRF in adults when compared to non-exercise control and MICT. Our findings offer a comprehensive basis that may potentially contribute to informing physical activity guidelines aimed at improving CRF in the general population.

The effect of different high-intensity interval training protocols on cardiometabolic and inflammatory markers in sedentary young women: A randomized controlled trial.

Few studies have reported the cardiovascular health effects of different high-intensity interval training (HIIT) protocols among sedentary young women. We investigated the impact of a traditional HIIT programme and a high-intensity circuit training (HICT) programme on lipid profiles and inflammatory cytokine levels in sedentary young women. Forty-two women were randomly assigned to HICT (body weight-based training), HIIT (cycling-based training), or control groups (n = 14 each). HICT and HIIT participants completed an 8-week training programme of three sessions per week. Total cholesterol (TC), triglyceride, high- and low-density lipoprotein, leptin, resistin, tumour necrosis factor-alpha (TNF-α), interleukin-8, and interferon-gamma levels were measured before and after the intervention. Post-intervention, TC and leptin were decreased in the HICT group. The HICT group also demonstrated increased lean mass, upper and lower limb strength, and balance, while the HIIT group displayed improved lower limb strength. Additionally, the control group showed significant increases in triglyceride levels, weight, body mass index, and fat mass. In conclusion, although both HICT and HIIT interventions showed improvements in cardiovascular health and physical fitness, participants in the HICT group experienced more health benefits.

Temporal Trends in the Physical Fitness of Hong Kong Adolescents Between 1998 and 2015.

Low physical fitness in adolescence is linked with increased cardiometabolic risk and early all-cause mortality. This study aimed to estimate temporal trends in the physical fitness of Hong Kong adolescents aged 12-17 years between 1998 and 2015. Physical fitness (9-min run/walk, sit-ups, push-ups, and sit-and-reach) and body size data in a total of 28,059 adolescents tested across five population-representative surveys of Hong Kong secondary school pupils, were reported. Temporal trends in means were estimated at the gender-age level by best-fitting sample-weighted linear regression, with national trends estimated by a post-stratified population-weighting procedure. Overall, there were small declines in 9-min run/walk (effect size (ES)=-0.29 (95%CI: -0.32, -0.26)) and sit-ups performance (ES=-0.24 (95%CI: -0.27, -0.21)), with negligible changes in push-ups and sit-and-reach performance. There were small concurrent increases in both mean height and body mass, with a negligible increase in sum of skinfolds. Trends in mean physical fitness and body size/were not always uniform across the population distribution. The small declines in mean 9-min run/walk and sit-ups performance for Hong Kong adolescents are suggestive of corresponding declines in cardiorespiratory fitness and abdominal/core endurance, respectively. Increased national health promotion strategies are required to improve existing trends.

Temporal trends in the physical fitness of Hong Kong children aged 6-12 years between 2003-04 and 2015-16.

Low physical fitness in childhood is linked with poor health now and in later life. This study estimated temporal trends in physical fitness for Hong Kong children aged 6-12 years from 2003-04 to 2015-16. Objectively measured body size and physical fitness data for 27,513 children were obtained from four population-representative surveys of Hong Kong primary school students. Temporal trends in means were estimated by population-weighted linear regression. Trends in distributional characteristics were visually described. Overall, there was a small increase in mean height (effect size (ES) = 0.20 (95%CI: 0.13, 0.28)), with a negligible increase (ES < 0.2) in mean body mass. When adjusted for trends in age, gender, and body size, there was a small decline in sit-and-reach performance (ES = -0.43 (95%CI: -0.43, -0.42)), a small improvement in 9-min run/walk performance (9-to-12-year-olds, ES = 0.26 (95%CI: 0.26, 0.27)), with negligible declines in handgrip strength, 6-min run/walk (6-to 8-year-olds), and sit-ups performance. Temporal trends were not always uniform across the population distribution, with declines in run/walk, sit-ups, and sit-and-reach performance generally largest in children with low fitness. Increased national health promotion strategies that address culturally specific factors are encouraged to further improve the existing trends, especially for children with low fitness.

Effects of increasing light versus moderate-to-vigorous physical activity on cardiometabolic health in Chinese adults with obesity.

Increasing daily physical activity (PA) is a practical way to decrease the risk of cardiometabolic diseases, while the studies on exercise intensity remain limited. The purpose of the present study was to compare the effects of increasing light PA (LPA) or moderate-to-vigorous PA (MVPA) for 12 weeks on cardiometabolic markers in Chinese adults with obesity. Fifty-three adults were randomly assigned to the 1) control group, 2) LPA group, and 3) MVPA group in free-living settings. The intervention effects on body composition, cardiorespiratory fitness, and cardiometabolic biomarkers were analysed using a generalized estimated equation model adjusted for baseline values and potential confounders. Compared with the control group, the MVPA group showed improvements in body composition, lipids, C-peptide, monocyte chemoattractant protein-1 (MCP-1), interleukin-8, leptin, and E-selectin. A favourable change in triglycerides and E-selectin were observed in the LPA group when compared to the control group. Lastly, improvements in waist circumference, C-reactive protein, and MCP-1 were observed in the MVPA group when compared to those in the LPA group. Although increasing both LPA and MVPA improved certain cardiometabolic biomarkers, the latter may have more benefits. These findings imply that MVPA may reduce cardiometabolic disease risk more effectively than LPA, especially in Chinese adults with obesity.

Associations Between Perceived Social Support, Perceived Competence, and Physical Activity in Hong Kong Children With Disabilities During the COVID-19 Pandemic.

This study aimed to examine the associations between perceived social support, perceived competence, and physical activity in children with physical and intellectual disabilities during the COVID-19 pandemic. During the third wave of the pandemic in Hong Kong (i.e., July through December 2020), 291 participants age 6-17 years from 27 special schools were included. After controlling for demographic variables, the total variance explained by perceived social support and perceived competence was 24%, F(2, 240) = 12.42, p < .001, with perceived competence having a stronger association with physical activity (ß = 0.29, p < .001) than perceived social support (ß = 0.07, p = .22). This study highlights two key facilitators for shaping physical activity involvement among children with disabilities during the COVID-19 pandemic.

Acute Physiological and Perceptual Responses to Whole-Body High-Intensity Interval Training Compared with Equipment-Based Interval and Continuous Training.

Low-volume, time-efficient high-intensity interval training (HIIT), which involves whole-body (WB) callisthenics exercises, has gained worldwide popularity in recent years. However, the physiological and perceptual impact of WB-HIIT in comparison to specialised, equipment-based training is relatively less studied. This study compared the acute physiological and perceptual responses to a single session of WB-HIIT, ergometer-based HIIT (ERG-HIIT) and conventional moderate-intensity continuous training (MICT). Fourteen physically inactive adults (age: 28.4 ± 6.5 years, VO2peak: 31.0 ± 6.2 mL· kg-1· min-1) underwent three main trials (WB-HIIT: 12 x 30-s high-intensity callisthenics workout; ERG: HIIT: 12 x 30-s high-intensity cycling bouts; MICT: 30-min cycling at 50% peak power output) in a randomized cross-over order 3-7 days apart. The mean session heart rate (HR) and perceived exertion were comparable across all three protocols (p > 0.05). WB-HIIT attained a similar peak HR (87.4 ± 9.4 %HRmax) as that of ERG-HIIT (83.0 ± 8.6 %HRmax), and significantly greater than that of MICT (78.7 ± 5.5 %HRmax, p = 0.001). However, WB-HIIT induced significantly higher blood lactate levels (7.2 ± 1.8 mmol/L) compared to both ERG-HIIT (5.1 ± 1.3 mmol/L, p < 0.05) and MICT (3.1 ± 1.5 mmol/L, p < 0.001). The participants reported higher self-efficacy and greater enjoyment with WB-HIIT compared to MICT (p < 0.05). The mean HR and perceived exertion responses to WB-HIIT are comparable to those of equipment-based HIIT and MICT; however, WB-HIIT results in greater metabolic strain than both other modalities. Despite this, the overall perceptual responses to WB-HIIT are positive, suggesting that it could be a viable exercise alternative, especially for individuals with limited exercise time and restricted access to facilities and equipment.

Movement behaviors and mental health of caregivers of preschoolers in China during the COVID-19 pandemic.

This study aimed to examine the associations between physical activity (PA), sedentary behavior (SB), sleep, and the mental health of caregivers of preschool children following the COVID-19 outbreak. From 5 October to 16 December 2020, responses from 2476 respondents in China were collated through an online survey or a written questionnaire. Movement behaviors (PA, SB, screen time, and sleep), mental health (depression, anxiety, and stress), and demographic information were self-reported by the respondents. Linear mixed models were used for data analysis. Valid responses were received from 2002 caregivers (35.5 ± 4.9 years old, 76.3% females) of children between 3 and 6 years old in China (Hong Kong 3.2%, Shanghai 20.6%, Guangzhou 34.1%, Guiyang 26.7%, Xuzhou 11.3%, Xi'an 4.1%). A higher level of PA was associated with a lower score of depression, while lower SB and longer sleep duration were associated with lower scores of depression, anxiety, and stress. Meeting the Canadian 24-h movement guidelines was associated with less symptoms of depression, anxiety, and stress. Higher PA was associated with lower levels of depression, while longer sleep and lower SB were associated with better scores of depression, anxiety, and stress. Meeting the Canadian 24-h movement guidelines has been associated with better mental health during the COVID-19 pandemic. Interventions to improve mental health among caregivers should involve enhancing their overall movement behaviors.

Active video game on children and adolescents' physical activity and weight management: A network meta-analysis.

We synthesized evidence on the effectiveness of active video games (AVGs) versus no AVG-applied comparators on various physical activity (PA) levels and weight management outcomes in children and adolescents. We analyzed the comparative evidence on different sub-categories of AVGs and ranking the best option. An overview of systematic reviews (SRs) and network meta-analysis (NMA) (PROSPERO: CRD42021248499) was employed. A search for relevant literature published in English was conducted in six electronic databases from their inception until April 2021. SRs consisting of randomized control trials (RCTs) and satisfying our PICOS inclusion criteria were included. RCTs included were a comparison of groups among children and adolescents between 6 and 21, where groups with AVG interventions were compared with groups without them. Direct head-to-head pairwise meta-analyses were conducted using weighted mean difference between the two groups, and the comparative effectiveness of different sub-categories of AVGs was analyzed indirectly using NMA. Overall, 17 SRs were identified from the 6036 screened citations. Of these, 350 citations were retrieved, and 12 RCTs were finally included. Compared with no AVG group, AVG groups were shown to be more effective in achieving vigorous, moderate-to-vigorous, and moderate PA levels, and decreased BMI and body fat. NMA showed that rhythmic dance games had the highest probability of being the most effective sub-category for reducing BMI. AVGs are effective in attaining vigorous, moderate to vigorous, and moderate PA levels, and reducing BMI and body fat among children and adolescents. Dance appears to be the best option for reducing BMI among AVG subcategories.

Alternating high-intensity interval training and continuous training is efficacious in improving cardiometabolic health in obese middle-aged men.

BACKGROUND: High-intensity interval training (HIIT) or moderate-intensity continuous training (MICT) alone has been shown to improve metabolic health, but the effects of alternating the two training approaches as often practiced in real life remained unclear. PURPOSE: To examine the effects of HIIT or MICT alone or alternating HIIT-MICT on cardiometabolic responses in inactive obese middle-aged men. METHODS: Forty-two participants (age: 42 ± 5 y; BMI: 26.3 ± 2.1 kg m-2) were randomly assigned to four groups: HIIT (12 x 1-min running bouts at 80-90% HRmax interspersed with 1-min active recovery at 50% HRmax), MICT (40-min brisk walk at 65-70% HRmax), alternating HIIT-MICT or a non-exercise control group (CON). Exercise sessions were conducted three times per week for 16 weeks. Maximal oxygen uptake (VO2max), body composition (by bioelectrical impedance analysis), blood pressure, fasting blood glucose, insulin resistance (HOMA-IR) and lipid profile were assessed at baseline and after the 16-week intervention. Enjoyment and self-efficacy were also assessed at the end of intervention. RESULTS: All exercise groups showed a similar VO2max increase of ∼15% (HIIT: 34.3 ± 4.4 vs 39.1 ± 5.4; MICT: 34.9 ± 5.0 vs 39.4 ± 7.2; and alternating HIIT-MICT: 34.4 ± 5.0 vs 40.3 ± 4.6 mL kg-1min-1) compared to baseline and CON (all p < 0.05). Weight, BMI, % fat and waist circumference also showed similar reductions in all exercise groups compared to baseline and CON (all p < 0.05). No significant group difference was observed for all blood markers. Compared to baseline, total cholesterol decreased after HIIT-MICT, while HIIT significantly decreased fasting insulin level and improved insulin resistance (p < 0.05). Enjoyment, self-efficacy and adherence were similar among all exercise groups. CONCLUSION: HIIT or MICT alone or alternating HIIT-MICT similarly improve cardiovascular fitness and body composition in obese middle-aged men despite differences in total training volume and time commitment.

Relationships of physical activity and sedentary behaviour with the previous and subsequent nights' sleep in children and youth: A systematic review and meta-analysis.

The interrelationships between sleep and daytime movement behaviours have been examined at interindividual level. Studies of within-person, temporal relationships of daytime physical activity (PA) and sedentary behaviour with the previous and subsequent nights' sleep are increasing. The present systematic review and meta-analysis synthesised the results of studies in school-aged children and youth. Eight databases (MEDLINE, PsycINFO, EMBASE, Global Health, PubMed, Web of Science, SPORTDiscus, and CINAHL) were searched for peer-reviewed articles that examined the association between daytime movement behaviours (including PA, sedentary time, or sedentary recreational screen time) and night-time sleep on the same day, or the association between night-time sleep and daytime movement behaviours the next day, in children and youth. A total of 11 studies comprising 9,622 children and youth aged 5-15 years met the inclusion criteria. Sedentary time was negatively associated with the subsequent night's sleep duration (r = -0.12, 95% confidence interval -0.23 to -0.00; I2  = 93%; p = .04). Positive relationships between PA and the previous or subsequent night's sleep duration were observed only for studies that adjusted for accelerometer wear time. There was some evidence suggesting that a longer sleep duration was associated with less sedentary time and a higher proportion of the daytime spent being physically active and vice versa, although the association was weak and based on a limited number of studies. From a clinical perspective, promotion of either sleep hygiene or daytime PA should be planned with considerations of the virtuous or vicious circle between these behaviours and monitor concurrent effects on the others.

Effect of sedentary behavior interventions on vascular function in adults: A systematic review and meta-analysis.

Sedentary behavior (SB) results in hemodynamic alterations within the vasculature, leading to vascular dysfunction that may be attenuated by various interventions. This systematic review and meta-analysis examined the effect of SB interventions on vascular function in adults using seven databases searched on December 17, 2020. All types of SB interventions were included such as short- and long-term interventions (≥7 days) in participants aged ≥18 years. The pooled effect (mean difference) of intervention on three outcomes, namely, flow-mediated dilation (FMD), shear rate (SR), and pulse wave velocity (PWV), was evaluated using random effects meta-analyses. The revised Cochrane risk-of-bias tool for randomized trials was employed to assess the quality of the included studies. Twenty-six studies (21 short-term and six long-term interventions) involving 669 participants from eight countries were included. Evidence from meta-analysis showed that short-term interventions targeting SB improved FMD by 1.50% (95% confidence interval [CI] 1.00-1.99) and increased SR by 12.70 S-1 (95% CI 7.86-17.54); no significant pooled effect was found for PWV. Long-term SB interventions resulted in a 0.93% increase in FMD (95% CI 0.25-1.62) and had no significant effect on PWV. Findings of this systematic review and meta-analysis suggest that both short- and long-term SB interventions improved FMD but had no effect on PWV. Short-term interventions had a greater effect in improving lower extremity arterial function. Further studies targeting long-term SB interventions on vascular function in adults are warranted.

Frequency of interruptions to prolonged sitting and postprandial metabolic responses in young, obese, Chinese men.

This study aimed to examine the effects of 3-min light-intensity walking every 30 min (3-min) and 6-min light-intensity walking every 60 min (6-min) compared with prolonged sitting (SIT) on the postprandial metabolic responses in young, centrally obese, Chinese men. Twenty-one Chinese men with central obesity (age, 23 ± 4 years; body mass index, 29.8 ± 3.2 kg·m-2; waist circumference, 98.7 ± 7.1 cm; mean ± SD) underwent three 6-h experiments with a 7-day washout period, SIT, 3-min, and 6-min, in randomized order. Compared with SIT, neither walking condition showed differences in total and net incremental area under the curve (tAUC and iAUC, respectively) for glucose, insulin, nor non-esterified fatty acids. The tAUC and iAUC for triglycerides for the SIT condition (10.8 [9.3, 12.2] and 4.4 [3.7, 5.1] mmol·h·L-1, respectively; mean [95% confidence interval]) was higher than 3-min (10.4 [9.0, 11.8] and 3.8 [3.3, 4.3] mmol·h·L-1, respectively, both Ps <0.05) and 6-min (9.6 [8.1, 11.0] and 3.5 [2.9, 4.2] mmol·h·L-1, respectively, both Ps <0.01) conditions. Interrupting prolonged sitting regardless of frequency-reduced postprandial triglycerides. A higher volume of physical activity may be required to obtain greater glycaemic benefits in young Chinese men with central obesity.

Interval training versus moderate-intensity continuous training for cardiorespiratory fitness improvements in middle-aged and older adults: a systematic review and meta-analysis.

Interval training has been promoted as a superior, time-efficient exercise strategy for enhancing cardiorespiratory fitness in the ageing population. This study assessed the effectiveness of interval training compared with that of moderate-intensity continuous training (MICT) for improving cardiorespiratory fitness in middle-aged and older adults. Six databases were systematically searched for studies with exercise interventions (minimum 2-week duration). Meta-analyses were conducted for within-group and between-group comparisons of maximal oxygen uptake (VO2max). Sub-group analysis was performed using the nature of interval training (high-intensity interval training [HIIT] and sprint interval training [SIT]). Of 3,257 studies, 14 were included (429 participants). Within-group analyses demonstrated significant VO2max improvements (mL/kg/min) following interval training (mean difference: MD = 2.26; 95% confidence interval [CI] = 1.50-3.02) and MICT (MD = 1.34; 95% CI = 0.45-2.23]. When comparing the modes of training, the gain in VO2max was significantly greater following interval training (MD = 1.10; CI = 0.55-1.64). Sub-group analysis showed that HIIT (MD = 1.04; CI = 0.21-1.88) and SIT (MD = 1.18; CI = 0.60-1.76) resulted in superior VO2max gain than MICT. This study provides evidence synthesis for interval training as a viable exercise strategy to improve cardiorespiratory function in healthy ageing.

Effects and dose-response relationship of high-intensity interval training on cardiorespiratory fitness in overweight and obese adults: a systematic review and meta-analysis.

This study aims to quantify the effects of high-intensity interval training (HIIT) on cardiorespiratory fitness (CRF) by considering potential moderators and to characterise dose-response relationships of HIIT variables that could maximise CRF improvements in overweight and obese adults. Following a comprehensive search through four electronic databases, 19 studies met eligibility criteria. Random-effects models were applied to weight all included studies and to compute the weighted mean standardised mean differences (SMDwm). Meta-analysis showed that HIIT was a highly effective approach for improving CRF in overweight and obese adults (SMDwm = 1.13). Effects were modified by sex and baseline CRF level. Dose-response relationship analysis provided some preliminary data regarding the training period, training intensity, and session duration. However, it is still not possible to provide accurate recommendations currently. Further studies are still needed to identify the most appropriate training variables to prescribe effective HIIT programmes for improving CRF in overweight and obese adults.

Associations between perceived and actual physical literacy level in Chinese primary school children.

BACKGROUND: The concept of physical literacy (PL) is gaining popularity within public health and physical education circles. However, little is known about the relationship between perceived and actual PL levels among school-aged children. The aim of this study is to explore the associations between perceived and actual levels of PL of primary school students in China. METHODS: A total of 327 children (153 boys and 174 girls) with a mean (SD) age of 10.0 (±1.0) years were included for analysis. PL perceptions were measured using the Perceived Physical Literacy Instrument. Children's actual level of PL was objectively assessed by the Chinese version of the Canadian Assessment of Physical Literacy, 2nd edition, which consists of four domains: Daily Behavior, Physical Competence, Motivation and Confidence, and Knowledge and Understanding. Pearson's correlation coefficients were calculated to examine the relationship between students' perceived and actual PL levels, whereas Multivariate Analysis of Variance (MANOVA) was calculated to investigate the gender, relative age differences, and interaction effect (2 × 4) on perceived and actual PL levels respectively. RESULTS: Significant correlations were observed between the perceptions and actual PL scores in both boys (r = .46, p < .01) and girls (r = .41, p < .01). Low to moderate significances were shown between each domain of perceived PL and actual PL (from .16 to .49). Further MANOVA results revealed that there were significant gender differences in the Daily Behavior domain of actual PL (F (1, 319) = 30.15, p < .001, Wilks' Λ = 540.88, η2partial = .09). Overall, boys had both higher actual PL scores (58.9) and PL perceptions (37.3) than girls. Neither relative age effect nor interaction effect (2 × 4) was observed for the current participants in all the variables. CONCLUSIONS: This study is the first to examine the associations between the perceived and actual levels of PL in Chinese children. Additional studies should explore the importance of children's perceptions of PL when assessing the actual level of PL in physical education and health settings. Girls should be more encouraged by PE teachers to participate actively in physical activities in the school environment.

The effect of low-volume high-intensity interval training on cardiometabolic health and psychological responses in overweight/obese middle-aged men.

High-intensity interval training (HIIT) has been proposed as a time-efficient exercise protocol to improve metabolic health, but direct comparisons with higher-volume moderate-intensity continuous training (MICT) under unsupervised settings are limited. This study compared low-volume HIIT and higher-volume MICT interventions on cardiometabolic and psychological responses in overweight/obese middle-aged men. Twenty-four participants (age: 48.1±5.2yr; BMI: 25.8±2.3kg·m-2) were randomly assigned to undertake either HIIT (10 X 1-min bouts of running at 80-90% HRmax separated by 1-min active recovery) or MICT (50-min continuous jogging/brisk walking at 65-70% HRmax) for 3 sessions/week for 8 weeks (2-week supervised + 6-week unsupervised training). Both groups showed similar cardiovascular fitness (VO2max) improvement (HIIT: 32.5±5.6 to 36.0±6.2; MICT: 34.3±6.0 to 38.2±5.1mL kg-1 min-1, p < 0.05) and %fat loss (HIIT: 24.5±3.4 to 23.2±3.5%; MICT: 23.0±4.3 to 21.5±4.1%, p< 0.05) over the 8-week intervention. Compared to baseline, MICT significantly decreased weight and waist circumference. No significant group differences were observed for blood pressure and cardiometabolic blood markers such as lipid profiles, fasting glucose and glycated haemoglobin. Both groups showed similar enjoyment levels and high unsupervised adherence rates (>90%). Our findings suggest that low-volume HIIT can elicit a similar improvement of cardiovascular fitness as traditional higher-volume MICT in overweight/obese middle-aged men.

Cross-validation of the Canadian Assessment of Physical Literacy second edition (CAPL-2): The case of a Chinese population.

The present study aimed to culturally adapt the Canadian Assessment of Physical Literacy, Second Edition (CAPL-2) and examine its validity and reliability among Chinese children aged 8 to 12 years. The original manual of CAPL-2 was translated and culturally adapted from English into Chinese. A total of 327 children (153 boys, mean age = 10.0) completed CAPL-2 (Chinese) assessments. Internal consistency reliability and construct validity for subscales and total model was explored. Results reported a good fit after adjusting for covariation paths, chi-square (χ 2 = 70.16, df = 43, p < 0.05), RMSEA = 0.04, 90% CI (0.024 - 0.062), CFI = 0.94, TLI = 0.90. Motivation and Confidence showed a good internal consistency (α = 0.82), compared to Knowledge and Understanding (α = 0.52). In general, there were few significant correlations between age and the subdomains as developmentally expected, and gender differences were observed with boys performing better than girls in total CAPL2 (Chinese) scores. This study was the first to cross-validate the CAPL-2 into the Chinese population. CAPL-2 (Chinese) offers the possibility of assessing physical literacy for researchers and practitioners and Chinese children's physical literacy development could be easily tracked in school settings.

Results from Hong Kong's 2019 report card on physical activity for children and youth with special educational needs.

BACKGROUND: /Objective: The Active Healthy Kids 2019 Hong Kong Report Card on Physical Activity for Children and Youth with Special Educational Needs (SEN) provides evidence-based assessments for nine indicators of physical activity behaviors and related sources of influence for 6- to 17-year-olds with SEN in Hong Kong. This is the first Report Card for this population group in Hong Kong. METHODS: The best available data between 2008 and 2019 were reviewed by a panel of experts. Following the Active Healthy Kids Global Alliance (AHKGA) development process, letter grades were assigned to nine indicators (Overall Physical Activity, Organized Sport Participation, Active Play, Active Transportation, Sedentary Behaviors, Family & Peers, School, Community & Environment, and Government Strategies & Investments). RESULTS: Two behavior indicators (Overall Physical Activity: F; Sedentary Behaviors: D+) and two contextual indicators (School: B; Government Strategies & Investments: C-) were assigned a letter grade. The remaining indicators including Organized Sport Participation, Active Play, Active Transportation, Family & Peers, and Community & Environment were not graded due to insufficient data. CONCLUSIONS: A majority of children and youth with SEN in Hong Kong are physically inactive and have a high level of sedentary behaviors. Schools are ideal settings to promote physical activity for this population. There is a need to develop a comprehensive surveillance system to monitor this population, assess efforts to improve the grades, and promote physical activity opportunities for children and youth with SEN.

Effect of pre-exercise ingestion of α-lactalbumin on subsequent endurance exercise performance and mood states.

This study investigated the effect of pre-exercise α-lactalbumin ingestion on subsequent endurance exercise performance, muscle pain and mood states. In a two-stage cross-over counterbalance design, eleven male endurance runners (age: 31 (se 2) years, height: 169·5 (se 4·4) cm, weight: 63·6 (se 5·1) kg, V̇O2max: 58·8 (se 6·3) ml/kg per min) consumed two solutions (carbohydrate+α-lactalbumin, CA; carbohydrate+whey protein isolate, CW) 2 h before a self-paced 21-km run. Creatine kinase, IL-6, muscle pain, pressure pain threshold (PPT) and mood states were assessed 2 h before exercise, immediately before exercise (Pre-ex0) and immediately after exercise (Post-ex0). No difference was found in 21-km running performance between two trials (CA v. CW: 115·85 (se 5·20) v. 118·85 (se 5·51) min, P=0·48). Compared with CW, CA led to higher PPT at Pre-ex0 (41·77 (se 2·27) v. 35·56 (se 2·10) N/cm2, P<0·01) and Post-ex0 (38·76 (se 3·23) v. 35·30 (se 3·55) N/cm2, P=0·047). Compared with CW, CA reduced the feeling of fatigue at Post-ex0 (P<0·01); CA also reduced salivary cortisol levels at Post-ex0 (0·72 (se 0·07) v. 0·83 (se 0·13) ng/ml, P<0·01). In conclusion, the ingestion of α-lactalbumin did not improve the 21-km time-trial performance. However, compared with the pre-exercise ingestion of whey protein, that of α-lactalbumin led to superior results during similar levels of endurance exercise: it elevated PPT and reduced the feeling of fatigue and the cortisol levels.