Mukherjee, Swarup

Inadequate hydration before, during and after exercise puts the safety and well-being of Singaporean youths at risk especially when sports training and Physical Education (PE) lessons are conducted outdoors, under the hot and humid weather conditions of Singapore. The study examined the exercise knowledge of youth athletes in Singapore schools: 586 youth athletes from four primary schools, four secondary schools and one junior college. All participants completed a validated exercise hydration knowledge quiz that was developed based upon the consensus statements and position stands of two international sports associations. An average knowledge score of 44.7±14.0% (range 0–87.1%) was obtained, which was significantly below the minimum competence score of 80%. Post-exercise hydration knowledge was lacking when compared to pre-exercise and during-exercise hydration knowledge. Overall, exercise hydration knowledge gaps were identified, in particular for post-exercise hydration; still the majority of participants from all schooling levels did not attain the competence score of at least 80%. Coach education and PE training programmes should specifically target and ameliorate these knowledge deficiencies to empower youth athletes to take personal responsibility for their safe participation and training in sports.

An investigation was done to determine the acceptability of the Lactate Pro LT -1710( blood lactate analyser while using a multiple-tester approach by assessing its accuracy, consistency, reliability and validity by comparing it to the YSI 2300 STAT PlusTM as the reference blood lactate analyser. The study was conducted in three phases separated seven days apart. The participants (n=9) completed the Bruce protocol on the motorised treadmill in the phase 1 and 2 and an all-out 30 s sprint on the non-motorised treadmill in the third phase. Pre and post-exercise capillary blood samples were collected from the finger-tip of the participants. Blood lactate data for all the three test days were pooled to determine the overall comparative agreement between the two analysers over a range of blood lactate values 0-16.2 mmol.L-1). A significant and high correlation was obtained for the combined pooled data (r=0.994, p<0.05). The ratio limits of agreement for pooled pre-exercise, pooled post-exercise and combined data were 00400.91, 0.61-0.84 and 0.53-0.90 respectively indicating the consistency of the blood lactate analysis by the Lactate Pro 1710(r) over a range (1-16.2 mmol.L-1) of blood lactate values. This study found the Lactate Pro 1710 blood lactate analyser to be acceptably accurate, consistent, reliable and valid to be used under varied exercise and training situations, especially when multiple testers are likely to be involved in the analysis.

Body composition is an important aspect of soccer fitness. There is a dearth of longitudinal data on the intraseasonal variation in the body composition parameters of youth professional soccer players especially of Asian origin. This study assessed the body composition profile of the Asian youth professional soccer players (n=20; Mean ± SD, age 17.5 ± 0.3 years, stature 1.73 ± 0.04 m, body mass 67.2 ± 7.5 kg) through the entire season. Body mass, percentage body fat (% BF), lean body mass (LBM) and bone mineral density (BMD) of outfield youth professional soccer players was determined using dual-energy x-ray absorptiometry (DXA) during the pre-season, early in-season and end mid-season respectively. Results showed that the Asian youth professional soccer players had similar anthropometric characteristics compared to Asian adult elite players but were shorter and lighter than European youth players. There was a significant decrease (p < 0.05) in the % BF and a significant increase (p < 0.05) in LBM during the pre-season period. However, negative adaptations during the competition phase indicated that training and competition load was insufficient to improve or maintain the adaptations in the % BF and LBM. The whole body BMD significantly increased through the soccer season. Area-specific BMD of the pelvis and the lower limbs showed positive osteogenic adaptations during the soccer season. Our results showed that the body composition parameters of Asian youth professional soccer players change through the soccer season. Such data can expand the bases of comparison between different soccer playing populations and add to the prospects of research on soccer performance. Further studies on the effect of body composition parameters on different aspects of soccer performance are desirable.

The performance capabilities and fitness characteristics of soccer players change through the playing season. There is a dearth of studies monitoring youth professional soccer players throughout the soccer season. The overall activity pattern in soccer is of an intermittent high-intensity type and the capability to perform repeated high-intensity running is one of the discriminatory performance quality among soccer players at different standards of the game. Repeated high-intensity running derives energy from all three energy systems in different proportions depending upon the fitness level of the players and the physiological demands of the game in terms of duration, intensity and frequency of the high-intensity running efforts required during the game. Therefore, performance tests in soccer must involve surrogate measurements of all the three energy systems.

The primary objective of the present study was to examine the indicators of repeated high-intensity running capability through the complete soccer season in youth professional soccer players. The participants (n = 20; mean ± SD age, 17.5 ± 0.3 years; stature, 1.73 ± 0.04 m; body mass, 67.2 ± 7.5 kg) represented the Singapore National youth (under-18) soccer team and also participated in a local professional soccer league. Following the results on reliability and the suitability of the test protocols and the measurements in the pilot data, the participants completed three laboratory tests and two field tests of both aerobic and anaerobic measurements on three occasions (pre-season, early in-season and end mid-season) minimum 8 weeks apart during a nine-month period of the soccer season. The laboratory tests included estimation of peak VO₂, test of intermittent high-intensity running capability on the motorised treadmill and a repeated sprint ability (RSA) test (6 × 6 s with 24 s recovery) on the non-motorised treadmill. The field tests included the test of intermittent high- intensity running capability (YoYo Intermittent Recovery Test Level 2) and a RSA test (8 × 20 m with 15 s active recovery). In addition, the present study also determined the percentage body fat (% BF) and lean body mass (LBM) using dual-energy X-ray absorptiometry (DXA), urinary total antioxidant capacity (uTAC, early morning sample, 72 hours post-match) and the match play work-intensity using heart-rate (HR) monitoring.

Results of phase-wise analysis of the measures showed a significant correlation between the performance in the laboratory and field test of intermittent high- intensity running with the amount of high-intensity exercise performed during match play (r = 0.55-0.82; p < 0.05). However, a non-significant negative correlation was observed between performance in the laboratory and field tests of RSA with the high-intensity exercise during match play (r= –0.11 to –0.43; p > 0.05). Results showed a nonsignificant correlation between peak VO₂ and the measures of intermittent high-intensity running (r=0.16-0.55, p > 0.05) and also between peak VO₂ and RSA performance (r= –0.07-0.26, p > 0.05). A significant correlation was detected between peak VO₂ and average work-intensity during match play (r=0.51-0.70, p < 0.05), but results showed a non-significant correlation between peak VO_2M and high-intensity exercise performed during match play (r=0.16-0.58, p > 0.05). Results also showed a significant negative correlation between % BF and performance in the laboratory and field tests of intermittent high-intensity running (r= –0.45 to – 0.77, p < 0.05), performance in the field test of RSA (r=0.53-0.64, p < 0.05) and with high-intensity work performed during match play (r= – 0.66 to – 0.57, p < 0.05). uTAC as a global measure of antioxidant capacity was not correlated with any of the performance measures (r= – 0.01 to 0.44, p > 0.05).

Results of the longitudinal analysis showed a significant change (p < 0.05; * significant change from previous phase) in performance in the laboratory-based test of intermittent high-intensity running capability (distance covered, mean; 2799, 3084*, 3038 m), laboratory-based RSA test (average mean power, mean; 629, 649, 691* W), YoYo IRT L2 (distance covered, mean; 818, 950*, 1032 m) and in the field-based RSA test (total time, mean; 24.4, 23.9*, 24.3 s) through different phases of measurement during the soccer season. A non-significant change (p > 0.05) was detected in peak VO₂ through the season (mean; 54.9, 53, 53.2 ml·kg^-1 ·min^-1). A non-significant change was also observed in the average work-intensity (% of maximal HR; 87.7, 90.1, 90 %) while results showed a significant change in the high-intensity work performed (% of total playing time; 57.5, 69.5*, 58* %) during match play. Results also showed a significant change (p < 0.05) in % BF (13.2, 11.2*, 12.4* %), % LBM (82.5, 84.5*, 83.3*) and uTAC (3.1, 2.7*, 3.0 mmol·L ^-1) through the season.

Results showed that repeated high-intensity running capability changes during the playing season in youth professional soccer players and this change was also reflected in the high-intensity work performed during match play. The results also showed that the indicators examined were sensitive to the change in this capability. Results of the study strongly supported the significance of low adiposity in performance of repeated high-intensity running. Based on the results, factors in addition to peak VO₂ like the muscle buffer capacity seemed to be important for repeated high-intensity running capability in youth professional soccer players. However, the results strongly supported the importance of a high aerobic capacity to maintain an overall high-work intensity during match play. Results indicated that uTAC might be a generic response to soccer training and performance.

In conclusion, the measures of intermittent high-intensity running might be the appropriate indicators for assessing the repeated high-intensity running capability in youth professional soccer players especially with respect to evaluating the match-related fitness in terms of high-intensity work performed during the soccer games. Motion characteristic analysis studies might be necessary to evaluate the extent to which performance in the RSA tests is reflected during match play. Further, the results strongly suggested that it might be of consequence to include fitness training even during the in season and that monitoring of the training intensity would be important to achieve the desired training gains and performance outcomes.

The anthropometric and blood parameters of 229 Singaporean adolescent youths, aged 13–15 recruited from seven secondary schools, were examined. Out of these youths, 71.5% were of healthy weight, 14.7% were underweight, 8.9% were overweight and 4.9% were obese, based on the BMI-for-age for adolescents set by the Ministry of Education. Health measurements like waist circumference, resting blood pressure and blood parameters—triglycerides, high-density lipoprotein, blood glucose derived from a fasted state, and insulin resistance—were obtained in accordance to standard international protocols. Clustered metabolic risk was used to quantify participants who were at significant risk of metabolic syndrome. Twenty-seven or 11.8% were identified as at-risk of metabolic syndrome CMR was significantly associated with body mass, waist circumference, resting systolic and diastolic blood pressure, fasted blood triglyceride, and fasted blood glucose. CMR was also moderately associated with IR. Waist circumference, percentage of body fat, and blood triglycerides and resting blood pressure were significantly correlated with IR. From the study, it was found that poor metabolic health is a concern among adolescent youths in Singapore, not only in those who were overweight or obese, but also in those who are of normal weight and underweight.

The four principal aims for the funded research were- (i) to elucidate the prevalence of physical activity and inactivity of Singaporean adolescent youths; (ii) to explain the relationships between physical activity, inactivity and metabolic syndrome and academic performance among Singaporean adolescents and (iii) to examine if 60 minutes of accumulated physical activity was sufficient to prevent insulin insensitivity among Singaporean adolescents and (iv) to examine the results of an intervention programme- PRIDE for PLAY- in raising the physical activity of adolescents in school.

The physical inactivity of Singaporean youths was examined using state-of-the-art ambulatory motion sensors (Actitrainer triaxial accelerometers) under free-living conditions on 3 weekdays and 2 weekend days. Participants included 128 male and 116 female adolescents, aged 12–15, from seven secondary schools. Neither boys nor girls met the national and international recommendation to accumulate at least 60 mins of moderate-to-vigorous physical activity (MVPA) on a daily basis for healthy cardiovascular health. Sedentary time over the weekday and weekend accounted for a majority of the accelerometer-monitored time. Step count accumulated in school was 16% greater than outside-of-school time. Under free-living weekday and weekend living conditions, Singaporean youths are not sufficiently engaged in MVPA and if this behaviour becomes entrenched, it may have dire consequences on the future physical and metabolic health of adult Singaporeans.

Safe regimens are a pre-requisite for children and youths who exercise and train in the hot and humid weather of Singapore. Coaches and Physical Education (PE) teachers have an important role in providing young people with up-to-date exercise hydration knowledge before, during and after exercise. However, it is not known if such professionals have the requisite knowledge and this was the main rationale for the study. Participants of this study consisted of 193 coaches and 164 PE teachers. They completed a 31-item exercise hydration knowledge quiz, with an established construct and content validity. An average competence score of 64.0±11.6% and a low passing rate of 7.8% were observed. At the 90th percentile, both coaches and PE teachers, had quiz scores of 77.4%, below the minimum passing score of 80%. Overall, professionals dealing with youths do not yet have the minimum competence in terms of exercise hydration knowledge and educational efforts at ameliorating this deficiency are recommended.