Comparing the effects of plyometric and isometric strength training on dynamic and isometric force-time characteristics.

The purpose of the study was to compare the change in dynamic and isometric force-time characteristics after plyometric (PLYO) or isometric strength training (ISO). Twenty-two endurance runners (age = 37 ± 6 years, stature = 1.71 ± 0.05 m, body mass = 62.7 ± 8.6 kg, weekly mileage = 47.3 ± 10.8 km) performed a countermovement jump (CMJ) and isometric mid-thigh pull (IMTP) test during pre- and post-tests. They were then randomly assigned to either PLYO or ISO group and completed 12 sessions of intervention over six weeks. The PLYO included drop jump, single leg bounding and split jump, and the ISO included IMTP and isometric ankle plantar flexion. Significant and large time x group interactions were observed for CMJ countermovement depth (P = 0.037, ƞ²p = 0.21) and IMTP and relative peak force (PF) (P = 0.030, ƞ² p = 0.22). Significant and large main effects for time were observed in CMJ height, peak power, propulsive phase duration, countermovement depth, reactive strength index modified, IMTP PF and relative PF (P < 0.05, 0.20 ≤ ƞ²p ≤ 0.65). Effect for time showed small improvement in CMJ height for both PLYO (P < 0.001, d = 0.48) and ISO (P = 0.009, d = 0.47), small improvement in CMJ PP in PLYO (P = 0.020, d = 0.21), large increase in countermovement depth (P = 0.004, d = 1.02) and IMTP relative PF (P < 0.001, d = 0.87), and moderate increase in propulsive phase duration (P = 0.038, d = 0.65) and IMTP PF (P < 0.001, d = 0.55) in ISO. There were large differences between groups for percentage change in countermovement depth (P = 0.003, d = 0.96) and IMTP relative PF (P = 0.047, d = 0.90). In conclusion, both PLYO and ISO improved CMJ jump height via different mechanisms, while only ISO resulted in improved IMTP PF and relative PF.

The associations between meeting 24-hour movement guidelines and adiposity in Asian Adolescents: The Asia-Fit Study.

Less is known about how compliance with 24-hour movement guidelines for physical activity (PA), sedentary behavior, and sleep affects adiposity in young people. The purposes of this study were to compare compliance with 24-hour movement guidelines in Asian adolescents and to examine the associations between compliance with 24-hour movement guidelines and body fat percentage. A sample of 12 590 adolescents aged 13.63 (± 1.01) years from eight Asian metropolitan cities including Bangkok (Thailand), Hong Kong SAR, Kuala Lumpur (Malaysia), Seoul (South Korea), Shanghai (China), Singapore, Taipei (Taiwan), and Tokyo (Japan) completed interviewer-administered questionnaires to assess moderate-to-vigorous PA, recreational screen time, sleep duration, and covariates. Body fat percentage was measured using bioelectrical impedance analysis. We found that compliance with 24-hour movement guidelines differed in Asian adolescents across the eight cities. Adjusting for covariates, there was a negative association between number of the guidelines being met and body fat percentage in Asian adolescents. In addition, meeting only the sleep guideline and both the PA and sleep guidelines had negative associations with body fat percentage compared with no guidelines being met. Our findings improve the understanding about how compliance with 24-hour movement guidelines benefit a healthy body weight in adolescents, as well as contribute to development of evidence-based 24-hour movement guidelines for Asian young people. Future research is needed to gain better insights into the directionality of the associations between compliance with 24-hour movement guidelines and adiposity, as well as the mechanisms underlying the associations in Asian adolescents.

Physical activity and health-related fitness in Asian adolescents: The Asia-fit study.

Purpose: The present study aimed to investigate and compare physical activity (PA) and health-related fitness in Asian adolescents, and to examine the associations between meeting PA guidelines and attaining fitness standards. Methods: A sample of 12,590 adolescents (Mage = 13.63 years, SD = 1.01) from eight Asian metropolitan cities completed measurements of PA, five field-based fitness tests, and covariates. The fitness test scores were further classified into Healthy Fitness Zone (HFZ) or Needs Improvement Zone (NIZ). Results: Findings showed that adolescents' levels of PA and fitness components differed by cities. City differences were also found in proportions of meeting PA guidelines and achieving the HFZs of aerobic capacity, muscular fitness, and body composition. After controlling covariates, meeting PA guidelines positively associated with being in the HFZs of aerobic and muscular fitness, but the association was not significant with being in the body composition HFZ. Conclusion: There was a large variation in PA and health-related fitness in adolescents across the eight Asian cities. Asian adolescents achieving PA guidelines were more likely to be in the HFZ of aerobic and muscular fitness. Prospective follow-up studies are warranted to gain better insights into the relationships between objectively-measured PA and fitness.

Moderate-to-vigorous physical activity attenuates the detrimental effects of television viewing on the cardiorespiratory fitness in Asian adolescents: the Asia-fit study.

BACKGROUND: Moderate-to-vigorous physical activity (MVPA) and television viewing are independently associated with cardiorespiratory fitness. However, limited evidence is available on their combined effects, specifically of MVPA and watching television, on cardiorespiratory fitness in the young Asian population. Therefore, the present study examined whether MVPA can attenuate the detrimental effects of prolonged television viewing on the cardiorespiratory fitness of Asian adolescents. METHODS: This is a cross-sectional study on 9553 adolescents (aged 12-15 years) from 8 Asian metropolitan cities (Tokyo, Hong Kong, Shanghai, Taipei, Bangkok, Kuala Lumpur, Seoul, and Singapore). Cardiorespiratory fitness was assessed by using a 15-m progressive aerobic capacity endurance run (PACER) test. The time spent on MVPA and watching television was assessed using the International Physical Activity Questionnaire-Short Form. RESULTS: MVPA was more closely associated with the PACER score than the duration of watching television. Compared with the reference group (i.e. those with the lowest levels of MVPA [< 30 min/day] and the most sedentary [≥3 h/day of television time]), PACER scores were significantly higher for those who met the physical activity recommendation (≥60 min/day in MVPA), regardless of the duration of television viewing. Conversely, girls in the least active group (< 30 min/day of MVPA) who watched television < 1 h/day demonstrated better PACER scores than the reference group. CONCLUSIONS: Sufficient MVPA (≥60 min/day) can attenuate the detrimental effects of excessive television viewing with cardiorespiratory fitness in Asian adolescents. In addition, the duration of television viewing had significant but weaker associations with cardiorespiratory fitness compared to MVPA.

Acute effect of 30 min of accumulated versus continuous brisk walking on insulin sensitivity in young Asian adults.

PURPOSE: The present study compared the acute effect of 30 min of accumulated versus continuous brisk walking on insulin sensitivity estimated in the fasted state and after an oral glucose tolerance test (OGTT) in young, healthy Asians. METHODS: Twenty-five healthy participants (12 males) were provided an OGTT the morning after: (i) accumulating three 10 min bouts of walking the previous evening; (ii) walking continuously for 30 min the previous evening or; (iii) resting the previous evening. Blood samples were taken in the fasted state and for 2 h post-OGTT. Insulin sensitivity was estimated from fasting blood glucose and insulin using the quantitative insulin sensitivity check index (QUICKI) and in response to the OGTT using an insulin sensitivity index (ISI-Matsuda). RESULTS: Fasting insulin was lower after continuous (P = 0.006) but not accumulated (P = 0.371) walking versus rest and did not differ between walking trials (P = 0.554). Similarly, QUICKI [Accumulated 0.381 (0.026) vs. Continuous 0.388 (0.029) vs. Rest 0.371 (0.031)] improved only with continuous (P = 0.006) and not accumulated walking (P = 0.255) compared with rest. There was a significant difference in ISI-Matsuda among groups [Accumulated 7.07 (3.04) vs. Continuous 7.29 (2.81) vs. Rest 6.14 (2.46), P = 0.050] with a Bonferroni t test suggesting this was between continuous walking and rest (P = 0.081). CONCLUSIONS: These findings demonstrate that 30 min of brisk walking is sufficient to improve insulin sensitivity in healthy, young Asians but only continuous and not accumulated walking provides this benefit. Further studies are needed to determine if accumulated and continuous exercise have different chronic effects on insulin sensitivity.

Psychometric Properties of the Attitudes toward Physical Activity Scale: A Rasch Analysis Based on Data From Five Locations.

This article describes the development and validation of the Attitudes toward Physical Activity Scale (APAS) to measure the attitudes, beliefs, and self-efficacy toward physical activity by children at the primary school level. The framework included: physical fitness, self-efficacy, personal best goal orientation in physical activity, interest in physical activity, importance of physical activity, benefits of physical activity, contributions of video exercise to learning in school subjects, contributions of video exercise to learning about health and environmental support. The sample comprised of 630 school students between grades 1 and 7 from five countries, namely Lithuania (29%), Poland (26%), Serbia (19%), Singapore (16%) and Zimbabwe (11%). Rasch analysis found empirical evidence in support of measurement validity of the APAS in terms of Rasch item reliabilities, unidimensionality, effectiveness of response categories, and absence of gender differential item functioning (DIF). The validation of the APAS according to the Rasch model meant that a dependable tool was established for gauging programme effectiveness of intervention programs on physical activity of primary school children in classroom settings at various geographical locations globally.

Effects of large exercise-induced weight loss on insulin sensitivity and metabolic risk factors in young males with obesity.

BACKGROUND: Obesity around the world is increasing at an alarming rate. One of the issues with obesity is whether exercise with large energy expenditure have any effect on obesity risk factors such as insulin resistance and coronary heart diseases. METHODS: Twenty participants (mean age: 19.5±1.09 years) with Body Mass Index (BMI) of >30 kg/m2, and body fat percentage (BF%) of >25% completed an institutionalized regimented training (IRT) for 16 weeks. 12-hour fasting blood samples were collected at least 48 hours after the last exercise session. Glucose and insulin variables were determined through an oral glucose tolerance test. Participants underwent 446 hours of IRT and ate from four standardized meal menus per day with a caloric intake of 3066 kcal. RESULTS: IRT resulted in a significant weight loss of 13.48±1.97 kg. Pre- and Post-Training total cholesterol (4.80±0.92 vs. 4.12±0.82 mmol/L) (P<0.01), low-density lipoprotein cholesterol (3.04±0.83 vs. 2.51±0.74 mmol/L) (P<0.01), triglycerides (1.19±0.57 vs. 0.74±0.30 mmol/L) (P<0.01) and apolipoprotein levels (Apo-A: 133.30±13.10 vs. 120.40±14.54 mg/dL; Apo-B: 88.08±25.72 vs. 70.12±18.21 mg/dL) (P<0.01) were significantly reduced, and glucose tolerance and insulin sensitivity were also improved. CONCLUSIONS: Large exercise-induced weight loss can be achieved through IRT and may be a solution for weight loss for individuals with obesity to reduce obesity related complications.

Effects of Isometric Strength and Plyometric Training on Running Performance: A Randomized Controlled Study.

Purpose: The aim of the study was to compare the effects of isometric strength (IST) and plyometric training (PT) on endurance running performance. Methods: Twenty-six endurance runners (18 males and 8 females; age 36 ± 6 years, stature 1.69 ± 0.05 m body mass 61.6 ± 8.0 kg, VO2max 50.4 ± 5.8 ml·kg-1·min-1) completed the countermovement jump (CMJ), isometric mid-thigh pull (IMTP), 2.4 km run time trial (2.4kmTT), running economy test (RE) and a graded exercise test measures at baseline. They were then randomly assigned to three groups, the control (CON), PT or IST group, and completed the circuit, plyometric or isometric training, respectively, twice a week for 6 weeks, while still continuing to perform their planned running training. They then completed the same set of measures performed at baseline post-intervention. Results: Significant time x group interactions and time main effect were observed for 2.4kmTT (P = .002, ƞ2p = .45 and P < .001, ƞ2 =0.72), maximal aerobic speed (MAS) (P = .006, ƞ2p = .39), CMJ height (P < .001, ƞ2p = .55) and IMTP relative peak force (P = .001, ƞ2p = .50) in favor of PT and IST. Significant main effect for time was observed for 2.4kmTT (P < .001, ƞ2p = .72), RE (P = .048, ƞ2p = .17), VO2max (P = .047, ƞ2p = .18), MAS (P < .001, ƞ2p = .63), CMJ height (P < .001, ƞ2p = .51) and IMTP relative peak force (P < .001, ƞ2p = .58). Conclusion: In conclusion, both PT and IST were similarly effective at enhancing running endurance performance. However, IST resulted in greater improvement to RE.

Determination, measurement, and validation of maximal aerobic speed.

This study determined Maximal Aerobic Speed (MAS) at a speed that utilizes maximal aerobic and minimal anaerobic contributions. This method of determining MAS was compared between endurance (ET) and sprint (ST) trained athletes. Nineteen and 21 healthy participants were selected for the determination and validation of MAS respectively. All athletes completed five exercise sessions in the laboratory. Participants validating MAS also ran an all-out 5000 m at the track. Oxygen uptake at MAS was at 96.09 ± 2.51% maximal oxygen consumption ([Formula: see text]). MAS had a significantly higher correlation with velocity at lactate threshold (vLT), critical speed, 5000 m, time-to-exhaustion velocity at delta 50 in addition to 5% velocity at [Formula: see text] (TlimυΔ50 + 5%v[Formula: see text]), and Vsub%95 (υΔ50 or υΔ50 + 5%v[Formula: see text]) compared with v[Formula: see text], and predicted 5000 m speed (R2 = 0.90, p < 0.001) and vLT (R2 = 0.96, p < 0.001). ET athletes achieved significantly higher MAS (16.07 ± 1.58 km·h-1 vs. 12.77 ± 0.81 km·h-1, p ≤ 0.001) and maximal aerobic energy (EMAS) (52.87 ± 5.35 ml·kg-1·min-1 vs. 46.42 ± 3.38 ml·kg-1·min-1, p = 0.005) and significantly shorter duration at MAS (ET: 678.59 ± 165.44 s; ST: 840.28 ± 164.97 s, p = 0.039). ST athletes had significantly higher maximal speed (35.21 ± 1.90 km·h-1, p < 0.001) at a significantly longer distance (41.05 ± 3.14 m, p = 0.003) in the 50 m sprint run test. Significant differences were also observed in 50 m sprint performance (p < 0.001), and peak post-exercise blood lactate (p = 0.005). This study demonstrates that MAS is more accurate at a percentage of v[Formula: see text] than at v[Formula: see text]. The accurate calculation of MAS can be used to predict running performances with lower errors (Running Energy Reserve Index Paper).

Running Energy Reserve Index (RERI) as a new model for assessment and prediction of world, elite, sub-elite, and collegiate running performances.

The purpose of this study was to utilize the Running Energy Reserve Index (RERI) model and two-trial procedure to predict all-out athletic performances. Twenty-nine trained athletes tested for differences between RERIE and RERIspd (hypothesis 1). Six sprint trained (ST), six middle distance (MD), and six endurance trained (ET) athletes were selected to test for differences in the value of the constant. The prediction of all-out run performances using the RERI model (hypothesis 2) and two treadmill trials procedure (hypothesis 3) were tested on eighteen trained athletes. Lastly, three trained athletes were utilized to predict all-out running performances utilizing two track trials equation (hypothesis 3). RERIE and RERIspd were significantly different between ST, MD, and ET athletes. The RERIE model with a fixed cE value of 0.0185 s-1 predicted all-out running performances to within an average of 2.39 ± 2.04% (R2 = 0.99, nT = 252) for all athletes, with treadmill trials to within an average of 2.26 ± 1.89% (R2 = 0.99, nT = 203) and track trials to within an average of 2.95 ± 2.51% (R2 = 0.99, nT = 49). The two trials equations predicted all-out track performances to within errors of 2.43%. The RERI model may be accurate in determining running performances of 200 m and 5000 m, and treadmill performances ranging between 5 and 1340 s with a high level of accuracy. In addition, the two-trial procedure can be used to determine short and middle distance running performances of athletes and world-class runners.

OMNI Scale of Perceived Exertion: mixed gender and race validation for Singapore children during cycle exercise.

The children's OMNI Scale of Perceived Exertion (RPE) has not been validated for children of Asian origin. The purpose was to validate the RPE for Singapore children, 12-15 years. 81 children of male and female of Chinese, Malay, and Indian ethnicities participated in the study. A cross-sectional, perceptual estimation paradigm using a multistage cycle ergometer protocol was used. Oxygen consumption ([Formula: see text]; ml min(-1)), heart rate (HR; beats min(-1)), and RPE for the Overall body (RPE-O), Legs (RPE-L), and Chest (RPE-C) were determined at the end of each continuously administered 3-min power output stage (PO) starting at 25 W with 25 W increments until exhaustion. For validation, linear regression analysis for all PO revealed that RPE-O, RPE-L, and RPE-C for each of the six gender-race and combined cohort distributed as positive linear functions of both [Formula: see text] (ml min(-1), ml kg(-1) min(-1)) and HR (beats min(-1)). All regression functions were statistically significant (P < 0.01). Differences between undifferentiated (RPE-O) and differentiated (RPE-L and RPE-C) at each PO stage were examined separately for the male (up to PO 8 [200 W]) and female (up to PO 5 [125 W]) cohorts. For the males, RPE-L was greater (P < 0.05) than both RPE-C and RPE-O only at PO 8. For the females, RPE-O was greater (P < 0.05) than RPE-C only at PO 3 and 4. OMNI Scale validity was established for male and female Asian children of Chinese, Malay, and Indian origin. Male and female children did not perceive the intensity of exertional perceptions to differ between the legs and the chest. As there were no differences between the undifferentiated and differentiated perceptual responses, a dominant signal was not observed.

A normalized rate of perceived exertion at ventilatory breakpoint for different exercise modalities and production of exercise intensity with self-regulation for Singapore children.

BACKGROUND: The purpose of this study was to identify a normalized RPE response at ventilatory breakpoint (Vpt) for male adolescents 13-17 years old, and whether these adolescents could self-regulate at target RPEs of 4 and 6. METHODS: Twenty healthy males participated in the study, with 10 males in each of the cycling and walking/running groups. Participants performed orientation and V̇O2peak trials before performing a perceptual estimation exercise trial to obtain RPE Vpt, and two production trials to assess self-regulation ability. RESULTS: Vpt corresponded to 67.7% V̇O2peak for the cycling group and 70.4% V̇O2peak for the walking/running group. There were no group differences on RPE-Overall Vpt (cycling: 4.6; walking/running: 4.4), RPE-Legs Vpt (cycling: 5.4; walking/running: 4.6), and RPE-Chest Vpt (cycling: 4.0; walking/running: 4.8). A normalized RPE-Overall Vpt response was identified at five. V̇O2 did not differ between the estimation and production trials at targets RPE of 4 (1.59 vs. 1.57 L·min-1) and 6 (1.87 vs. 1.79 L·min-1). Similarly, heart rate (HR) did not differ between estimation and production trials at targets RPE 4 (152.4 vs. 151.1 beats·min-1) and 6 (167.1 vs. 162.4 beats·min-1). Both V̇O2 and HR were significantly higher at RPE 6 compared to RPE 4. Responses were not affected by exercise mode or production sequence. CONCLUSIONS: This study demonstrated that undifferentiated and differentiated RPE Vpt were similar between cycling and walking/running participants. Male adolescents between 13- and 17-year-olds were able to use the OMNI scale to self-regulate exercise intensities that would be useful in field settings.

Sprint Kayaking Performance Enhancement by Isometric Strength Training Inclusion: A Randomized Controlled Trial.

Performing isometric strength training (IST) can enhance various sports performance. This study compared the effects of including IST on sprint kayaking performance as compared to traditional strength training. Twenty sprint kayaking athletes (age 22 ± 4 year, stature 1.71 ± 0.09 m, body mass 72.0 ± 11.4 kg) performed a 200-m kayak ergometer time trial (200mTT), isometric squat (IsoSqT), isometric bench press (IsoPress) and isometric prone bench pull (IsoPull) during the pre- and post-tests. Athletes were randomly assigned to either traditional strength training (TRAD) or IST group. Both groups performed a similar strength training program twice a week for six weeks. However, half the volume for squat, bench press and prone bench pull were replaced by IsoSqT, IsoPress and IsoPull, respectively, for the IST group. IsoSqT was performed at 90° knee angle, while IsoPress and IsoPull were performed at 90° and 120° elbow angles, respectively. Each isometric contraction was performed with maximum intensity and sustained for three seconds. A significant main time effect was observed for 200mTT (p < 0.001, ƞ2p = 0.68) and all isometric strength measures (p = 0.001-0.032, ƞ2p = 0.24-0.76) except rate of force development at 0-90 ms (RFD90) obtained from IsoSqT120 and IsoPress90. A group main effect was observed in RFD90 obtained from IsoSqT120 and IsoPull120 (p = 0.003-0.004, ƞ2p = 0.37-0.39). Time x Group interaction was observed for 200mTT (p = 0.027, ƞ2p = 0.68), peak force obtained from IsoSqT90, IsoPress90, and IsoPull120 (p = 0.004-0.006, ƞ2p = 0.36-0.38) and RFD90 obtained from IsoSqT120 and IsoPull120 (p = 0.012-0.015, ƞ2p = 0.28-0.30). Inclusion of IST resulted in greater improvement for sprint kayaking and strength performances then TRAD alone.

Mental Health among Adults during the COVID-19 Pandemic Lockdown: A Cross-Sectional Multi-Country Comparison.

Despite the global impact of COVID-19, studies comparing the effects of COVID-19 on population mental health across countries are sparse. This study aimed to compare anxiety and depression symptoms during the COVID-19 lockdown among adults from 11 countries and to examine their associations with country-level COVID-19 factors and personal COVID-19 exposure. A cross-sectional survey was conducted among adults (≥18 years) in 11 countries (Brazil, Bulgaria, China, India, Ireland, North Macedonia, Malaysia, Singapore, Spain, Turkey, United States). Mental health (anxiety, depression, resilient coping, hope) and other study data were collected between June-August 2020. Of the 13,263 participants, 62.8% were female and 51.7% were 18-34 years old. Participants living in Brazil had the highest anxiety and depression symptoms while participants living in Singapore had the lowest. Greater personal COVID-19 exposure was associated with increased anxiety and depression symptoms, but country-level COVID-19 factors were not. Higher levels of hope were associated with reduced anxiety and depression; higher levels of resilient coping were associated with reduced anxiety but not depression. Substantial variations exist in anxiety and depression symptoms across countries during the COVID-19 lockdown, with personal COVID-19 exposure being a significant risk factor. Strategies that mitigate COVID-19 exposure and enhance hope and resilience may reduce anxiety and depression during global emergencies.

Using Brain-Breaks® as a Technology Tool to Increase Attitude towards Physical Activity among Students in Singapore.

The purpose of this study was to investigate the effects of classroom-based Brain Breaks® Physical Activity Solution in Southeast Asia Singaporean primary school students and their attitude towards physical activity (PA) over a ten-week intervention. A total of 113 participants (8-11 years old) were randomly assigned to either an experimental (EG) or a control group (CG), with six classes to each group; the Brain Breaks® group (EG: six classes) and the Control group (CG: six classes). All EG members participated in a Brain Breaks® video intervention (three-five min) during academic classes and the CG continued their lessons as per normal. The student's attitudes towards PA in both research conditions were evaluated using the self-reported Attitudes toward Physical Activity Scale (APAS), applied before and after intervention. The effects of the intervention on APAS scores were analysed using a mixed model analysis of variance with Time as within-subject and Group as between-subject factors. The analysis revealed evidence in support of the positive effect of classroom video interventions such as Brain Breaks® on student's attitudes toward benefits, importance, learning, self-efficacy, fun, fitness, and trying to do their personal best in PA. The Brain Breaks® intervention provided a positive significant impact on students in Singapore. This study also revealed that interactive technology tools implemented into the school curriculum benefit students in terms of health and education.

Physical Activity among Adults Residing in 11 Countries during the COVID-19 Pandemic Lockdown.

During the novel coronavirus (COVID-19) pandemic, physical activity (PA) behaviors were altered worldwide due to public health measures such as "lockdown." This study described PA among adults residing in 11 countries during COVID-19 lockdown and examined factors associated with PA engagement. We conducted a cross-sectional anonymous survey among adults (≥18 years old) in 11 countries (Brazil, Bulgaria, China, India, Ireland, Malaysia, North Macedonia, Singapore, Spain, Turkey, United States). Of 11,775 participants, 63.7% were female and 52.8% were 18-34 years old. More than 40% of participants were insufficiently active (43.9%) and reported a decrease in their PA during lockdown (44.8%). Statistically significant differences were observed in (1) proportions of participants being insufficiently active, (2) level of PA, and (3) decrease in PA across the 11 countries. More stringent governmental policy responses were associated with greater likelihood of being insufficiently active during lockdown (adjusted odds ratio = 1.22, 95% confidence interval = 1.03, 1.45). Higher depression or anxiety scores were associated with greater likelihood of decreased level of PA during lockdown.We found substantial reductions in PA levels during COVID-19 lockdown across countries. Country-specific PA promotion interventions are needed during this and similar global emergencies.

Arm-pull thrust in human swimming and the effect of post-activation potentiation.

The aim of this study was to analyse the front-crawl arm-pull kinetics and kinematics, comparing it before and after post-activation potentiation (PAP), and the associations between variables describing of the arm-pull kinetics. Twelve male competitive swimmers were randomly assigned to perform two different warm-ups in a crossover manner: (i) non-PAP (control condition); and (ii) PAP (experimental condition). PAP consisted of 2 × 5 arm-pulls with resistance bands by both upper-limbs. Eight minutes later, participants underwent a 25 m all-out trial in front-crawl arm-pull. Kinetics (i.e., peak thrust, mean thrust and thrust-time integral) and kinematics (i.e., speed and speed fluctuation) were collected by an in-house customised system composed of differential pressure sensors, speedo-meter and underwater camera. There was a significant and large improvement of the arm-pull kinetics after completing the warm-up with PAP sets (0.010 < P < 0.054, 0.50 < d < 0.74). There were non-significant and small effects of PAP on speed (P = 0.307, d = 0.18) and speed fluctuation (P = 0.498, d = 0.04). Correlation coefficients among kinetic variables were significant with large associations (0.51 < R < 0.90, 0.001 < P < 0.088). In conclusion, warm-ups including PAP conditioning sets elicit a large improvement in the thrust, but with small improvement in performance. Variables used to characterise thrust are strongly correlated and hence can be used interchangeably.

Brain Breaks® Physical Activity Solutions in the Classroom and on Attitudes toward Physical Activity: A Randomized Controlled Trial among Primary Students from Eight Countries.

Classroom-based physical activity (PA) interventions have received considerable attention due to improvements seen in academic achievement, classroom behaviors, and attitude toward PA. The purpose of this study was to evaluate the effectiveness of the Brain Breaks® Physical Activity Solutions in changing children's attitudes toward PA. Students (N = 3036) aged 8-11 years from schools in Croatia, Lithuania, Macedonia, Poland, Romania, Serbia, South Africa, and Turkey were randomly assigned to either a control or an experimental group. The experimental group received Brain Breaks® videos during classroom sessions throughout the four months of intervention. Student attitudes toward PA were measured using the Attitudes toward Physical Activity Scale (APAS) before and after the intervention. Repeated measures ANOVA indicated a time interaction effect for all APAS variables except fitness. Time-by-group interaction effects with different effect sizes were found for most APAS variables, with the greatest gain effect noted in the experimental group for self-efficacy, followed by learning from the videos concerning PA benefits, exercise importance, and enjoyment from engaging in PA. This study provides evidence supporting Brain Breaks® in terms of learning experience, attitudes towards PA, and personal motivation. Using exercise videos is recommended as an interactive, technology-based PA solution that can be easily integrated into the school setting.

Effects of Pre-Exercise High and Low Glycaemic Meal on Intermittent Sprint and Endurance Exercise Performance.

The purpose of this study is to investigate the effects of ingesting either a high glycaemic index (HGI) or low glycaemic index (LGI) carbohydrate meal (preceding a 12 h overnight fast and where the meal was ingested 45-min prior to activity) on intermittent sprint and endurance exercise performance. Ten male varsity athletes from intermittent sports (age 23.6 ± 1.7 years, VO2max 51.9 ± 4.7 mL·kg-1·min-1) underwent a peak velocity (Vpeak) test and familiarisation session, followed by two experimental sessions in random order. Experimental sessions involved the ingestion of either an HGI or LGI meal, followed by the completion of the modified Loughborough Intermittent Shuttle Test (mLIST). There was no significant difference between HGI or LGI meals on sprint times (p = 0.62) and distance to exhaustion (p = 0.54) in the mLIST. Exercise heart rate, blood lactate and ratings of perceived exertion were also similar between the two meal trials throughout the mLIST (all p > 0.05). Subjective ratings of hunger, fullness, satiety and satisfaction were also not significantly different between the two meals. In conclusion, consuming either an HGI or LGI meal after a prolonged 12 h fast and ingesting the meal 45 min prior to exercise did not differ in either physiological, subjective and intermittent sprint and endurance performance outcomes.

Physiological differences between a noncontinuous and a continuous endurance training protocol in recreational runners and metabolic demand prediction.

This study investigated the physiological difference in recreational runners between a noncontinuous and a continuous endurance training protocol. It also aimed to determine physiological surrogate that could monitor metabolic demand of prolonged running in real-time. For data collection, a total of 18 active male recreational runners were recruited. Physiological (HR, RR, RER, VO2, BLa), and overall perceptual (RPEO) responses were recorded against three designed test sessions. Session 1 included VO2submax test to determine critical speed (CS) at anaerobic threshold (AT). Session 2 was the noncontinuous CS test until exhaustion, having 4:1 min work-to-rest ratio at CS, whereas session 3 was the continuous CS test till exhaustion. As 1-min recovery during session 2 may change fatigue behavior, it was hypothesized that it will significantly change the physiological stress and hence endurance outcomes. Results reported average time to exhaustion (TTE) was 37.33(9.8) mins for session 2 and 23.28(9.87) mins for session 3. Participants experienced relatively higher metabolic demand (BLa) 6.78(1.43) mmol.l-1 in session 3 as compared to session 2 (5.52(0.93) mmol.l-1). RER was observed to increase in session 3 and decrease in session 2. Student's paired t-test only reported a significant difference in TTE, VO2, RER, RPEO, and BLa at "End" between session 2 and 3. Reported difference in RPEO and %HRmax at "AT" were 5 (2.2) and 89.8 (2.60)% during session 2 and 6 (2.5) and 89.8 (2.59)% during session 3, respectively. Regression analysis reported strong correlation of %HRmax (adj. R-square = 0.588) with BLa than RPEO (adj. R-square = 0.541). The summary of findings suggests that decreasing RER increased TTE and reduced BLa toward "End" during session 2 which might have helped to have better endurance. The %HRmax was identified to be used as a better noninvasive surrogate of endurance intensity estimator.