Balasekaran, Govindasamy

This study investigated the physiological difference in recreational runners between a non continuous 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, ṼO2, BLa), and overall perceptual (RPEO) responses were recorded against three designed test sessions. Session 1 included ṼO2submax test to determine critical speed (CS) at anaerobic threshold (AT). Session 2 was the non continuous 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, ṼO2, 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.

Obesity has reached global epidemic proportions over the past 10 years. As countries become more affluent, their populations tend to adopt caloric balance problems that have plagued the USA and Western Europe. Obesity is classified as the second most serious reversible health problem, after smoking in the world today. The relationship between obesity and cardiovascular diseases is well documented. The increase in obesity in Asian countries is remarkable. In 2004, the prevalence of obesity in the adult population in Singapore increased upto 16% (high risk category: ≥ 27.5kg/m2) and prompted many forms of government action, encouraging collaboration between businesses, the educational system and non-governmental organizations. This paper reviews the rise of obesity in Singapore and some of the approaches being implemented to address this concern. Singapore, a multiethnic country, with Chinese, Indian and Malay populations, has to address diversity in customs, diet and religions to combat obesity. The collaborative efforts of various organizations such as the Ministry of Health (MOH), Ministry of Education (MOE) and the Health Promotion Board (HPB) have successfully improved the health status of Singaporeans. The fact that the rise in obesity in Singapore is lower than in other neighboring Asian countries attests to the partial success of the collaborative efforts.

The purpose of this study was to investigate the effects of soy protein supplementation to improve performance and recovery during repeated running anaerobic sprint test (RAST). Ten males (age: 23.2 ± 1.23 yrs) performed two RAST with a soy milk intervention (SOY; 500 mL soy milk + 4 g stevia sweetener) and a placebo control (CON; 500 mL water + 4 g stevia sweetener) over 7 days. The RAST consisted of six 35-m sprints with a 10-sec recovery between each sprint. The total effort time (sec) was not significant between SOY (32.77 ± 1.23) and CON (33.28 ± 1.71) (P = 0.179). Fatigue index in SOY (31.64 ± 5.20) was significantly lower than CON (37.30 ± 5.70) (P = 0.023). Mean power (Watts) (Soy: 499.27 ± 62.72, Con: 486.39 ± 86.13) (P = 0.410), relative power (Watts) (Soy: 9.34 ± 1.02, Con: 9.55 ± 1.51) (P = 0.461), peak blood lactate (mmol·L-1) (Soy: 9.75 ± 1.61, Con: 10.24 ± 1.90) (P = 0.488), and peak blood glucose (mmol·L-1) (Soy: 23.94 ± 3.90, Con: 25.09 ± 4.61) (P = 0.497) between trials were not significant. Peak blood lactate (r = -0.654) and glucose (r = -0.662) concentrations were inversely associated with mean power in the SOY trial. The results indicate that the soy milk intervention in RAST significantly lowered the fatigue index and, therefore, may be used to enhance sports performance involving anaerobic activities.

The study examined the motion sensor outputs of Singaporean children and adolescents of both sexes to walking and running on a motorized treadmill (Quinton Series 90) under controlled laboratory conditions. 58 youths of normal body mass (N=58, age: 13.2±3.0 y; height: 1.53±0.02 m; body mass: 45.5±14.2 kg; BMI: 18.8± 3.0 kg/m2; Tanner rating: 2.5±1.3) were recruited for the study. Accelerometer (ActiGraph GT 1 M) activity (ActiCounts in counts/min) and step rate (ActiSteps in steps/min) and pedometer (Omron HJ 005-E) step rate (PedoSteps in steps/min), oxygen uptake (in ml/kg/min) and heart rate (in bpm) were obtained from 5-minutes stages of 0 % gradient of treadmill walking at 4 km/hr and running at 6 km/hr and 8 km/hr. Walking at 4 km/hr was estimated at 4.0-6.0 METs, whilst running at 6 km/hr and 8 km/hr was estimated at 6.3-8.6 and 10.0-11.4 METs, respectively. Motion sensor outputs increased significantly with treadmill speeds (76-101 % for ActiCounts; 22-24 % for ActiSteps and18-25 % for PedoSteps, all p<0.01) as did oxygen uptake (48-55 %) and heart rate (27-28 %) but there was no sex difference in activity or step rate or physiological responses (p>0.01). No meaningful relationships were obtained between accelerometer activity rate and oxygen uptake or heart rate. There was acceptable agreement between accelerometer and pedometer step rate for the walking and running on the treadmill but the difference between accelerometer and pedometer step rate was smallest at a treadmill running speed of 6 km/hr. These results show that accelerometer and pedometer step rates are useful and suitable measurements of physical activity involving walking and running among Singaporean children and adolescents of normal body mass. Further investigations are necessary to fully exploit the use of accelerometer data in physical activity research among young people.

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, ƞ²p = 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.

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.

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.

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.