Consensus recommendations on training and competing in the heat.

Exercising in the heat induces thermoregulatory and other physiological strain that can lead to impairments in endurance exercise capacity. The purpose of this consensus statement is to provide up-to-date recommendations to optimise performance during sporting activities undertaken in hot ambient conditions. The most important intervention one can adopt to reduce physiological strain and optimise performance is to heat acclimatise. Heat acclimatisation should comprise repeated exercise-heat exposures over 1-2 weeks. In addition, athletes should initiate competition and training in a euhydrated state and minimise dehydration during exercise. Following the development of commercial cooling systems (eg, cooling-vest), athletes can implement cooling strategies to facilitate heat loss or increase heat storage capacity before training or competing in the heat. Moreover, event organisers should plan for large shaded areas, along with cooling and rehydration facilities, and schedule events in accordance with minimising the health risks of athletes, especially in mass participation events and during the first hot days of the year. Following the recent examples of the 2008 Olympics and the 2014 FIFA World Cup, sport governing bodies should consider allowing additional (or longer) recovery periods between and during events, for hydration and body cooling opportunities, when competitions are held in the heat.

Consensus recommendations on training and competing in the heat.

Exercising in the heat induces thermoregulatory and other physiological strain that can lead to impairments in endurance exercise capacity. The purpose of this consensus statement is to provide up-to-date recommendations to optimize performance during sporting activities undertaken in hot ambient conditions. The most important intervention one can adopt to reduce physiological strain and optimize performance is to heat acclimatize. Heat acclimatization should comprise repeated exercise-heat exposures over 1-2 weeks. In addition, athletes should initiate competition and training in a euhydrated state and minimize dehydration during exercise. Following the development of commercial cooling systems (e.g., cooling vest), athletes can implement cooling strategies to facilitate heat loss or increase heat storage capacity before training or competing in the heat. Moreover, event organizers should plan for large shaded areas, along with cooling and rehydration facilities, and schedule events in accordance with minimizing the health risks of athletes, especially in mass participation events and during the first hot days of the year. Following the recent examples of the 2008 Olympics and the 2014 FIFA World Cup, sport governing bodies should consider allowing additional (or longer) recovery periods between and during events for hydration and body cooling opportunities when competitions are held in the heat.

Role of cardiorespiratory fitness and obesity on hemodynamic responses in children.

AIM: The purpose of this study was to examine the effects of cardiorespiratory fitness (CRF) and obesity on arterial blood pressure and its determinants at rest and during isometric handgrip exercise (IHG) in children. METHODS: Fourty-eight healthy children aged 11.6±0.3 (mean ±SE) years, (24 obese or overweight [OB/OV]; 24 normal weight [NO]) participated in the study. Both groups were divided into fit or unfit subgroups according to children's performance of an exercise test (PWC170). Arterial pressure and its determinants were recorded with the use of a photoplethysmographic device (FINOMETER) during 5 minutes of rest and 3 minutes of IHG at 30% of maximum voluntary contraction. RESULTS: At rest and during IHG, unfit OB/OV children had higher systolic, mean arterial pressure, and rate pressure product (P≤0.05) than fit OB/OV children whose responses were similar to NO children, fit or unfit. Changes from rest, in cardiac output, cardiac index, and stroke volume were higher in unfit than in fit OB/OV children (P≤0.05). Unfit OB/OV children exceeded their fit counterparts in several anthropometric measures. However, CRF was found to have a main effect on systolic blood pressure (P=0.05). CONCLUSION: Unfit versus fit OB/OV children had an exaggerated systolic blood pressure response at rest and during sympathetic activation, presumably coupled with higher cardiac output and cardiac oxygen demand. These results highlight the importance of fitness for health maintenance in obese and overweight children.

Effect of hypocaloric diet plus sibutramine treatment on hormonal and metabolic features in overweight and obese women with polycystic ovary syndrome: a randomized, 24-week study.

OBJECTIVE: To examine the effect of hypocaloric diet plus sibutramine on body composition, hormonal and metabolic parameters in overweight and obese patients with polycystic ovary syndrome (PCOS). DESIGN: Open-label, randomized study at an outpatient clinic. PATIENTS: A total of 59 overweight and obese (18-39 years old) women with PCOS. MEASUREMENTS: All patients were placed in a hypocaloric diet plus sibutramine (10 mg per day) for the first month and then on a hypocaloric diet plus sibutramine (10 mg per day, group S) or hypocaloric diet only (group D) for the subsequent 6 months. Body composition, hormonal and metabolic features and insulin sensitivity (oral glucose tolerance test, OGTT) were evaluated at baseline and at 3 and 6 months of treatment. RESULTS: Body weight reduced in both groups but the reduction was greater with sibutramine (-15.4+/-1.1 vs -11.1+/-1.9% in groups S and D, respectively, P<0.05). At 6 months, a greater percent of patients lost more than 10% of initial body weight in group S than D (81 vs 52.9%). In both groups, all women with abnormal OGTT at baseline presented normal glucose tolerance after 6 months. Free androgen index (FAI), glucose area under the curve and fasting triglyceride (TG) concentration were reduced after 6 months in group S only (P<0.05). No changes in cardiovascular risk factors, prolactin and hepatic enzymes levels were observed in both groups. CONCLUSION: A hypocaloric diet and a diet plus sibutramine both result in significant weight loss in overweight and obese women with PCOS. Patients who received sibutramine showed a greater weight loss and improvement in hyperandrogenemia and insulin sensitivity after 6 months of treatment. The amelioration of insulin resistance in this group could not be totally explained by weight loss. Total testosterone, FAI and TG levels reduction could be a possible mechanism. Finally, sibutramine increased compliance to diet and it was well tolerated from these patients.

Prevalence of overweight and obesity in a national representative sample of Greek children and adolescents.

OBJECTIVE: The aim of this study was to examine the prevalence of overweight and obesity in Greek school age children and adolescents. DESIGN: Nationwide representative survey. SETTING: Primary and secondary schools all over Greece. SUBJECTS: In all, 6448 students (50.4% boys, 49.6% girls) 6-17 years old. METHOD: A nationwide multistage procedure was followed to obtain a representative sample of youths. Body mass and height were measured by trained personnel. Data were collected between October 1990 and May 1991. RESULTS: According to the 12-month-International Obesity Task Force cutoff values, the overall prevalence of overweight was 17.3% (16.9% for boys, 17.6% for girls). The rate of obesity was 3.6% (3.8% for boys, 3.3% for girls). The prevalence of overweight and obesity was decreasing with age in girls (6-9 years: 23.2 and 6.7%, respectively, 10-17 years: 14.8 and 1.6%, respectively). In boys, the prevalence of overweight was higher in 10-17 years (19.3 and 2.7%, for the rate of overweight and obesity, respectively) than in 6-9 years (12.1 and 5.9%, respectively). CONCLUSION: The prevalence of overweight and obesity in Greek children and adolescents is comparable to that reported for most European countries.

Effect of eating frequency on body composition in 9-11-year-old children.

The aim of this study was twofold: a) to examine the association between eating frequency and body composition in children, and b) to identify possible factors that may explain this relationship. Body composition (anthropometry) and dietary intake (3-day food records) were assessed in a cohort of 151 children. After excluding the underreporters (n = 20), data from 131 children (66 boys and 65 girls) aged 9.9 +/- 0.1 yr with a BMI of 19.6 +/- 0.4 kg/m (2) (means +/- se) were used for further analysis. Children were categorized in tertiles based on the daily number of eating episodes. Physical activity was assessed in a subgroup of 48 volunteers with 4-day accelerometry (RT3, Stayhealthy Inc., Monrovia, CA, USA). The number of eating episodes was inversely associated (p < 0.05) with the sum of skinfolds (r = - 0.17) and % body fat (r = - 0.18) after controlling for age and sex. Frequent eaters presented lower total (p < 0.05) and central adiposity (p < 0.01) compared with the infrequent ones. This was despite the fact that energy intake was higher for the frequent eaters (2077.0 +/- 64.3 vs. 1813.0 +/- 37.8 kcals/day for the frequent and the infrequent eaters, respectively, p < 0.05). Actually, frequent eaters devoted more time to physical activity than infrequent ones (624.7 +/- 13.5 vs. 559.2 +/- 23.1 min/day, p < 0.05). In conclusion, high eating frequency was associated with more favorable body composition in this cohort of school children. Increased energy expenditure due to physical activity may, at least in part, explain the favorable body composition of children who eat frequently.

Somatic and physical traits affecting sprint swimming performance in young swimmers.

The aim of this study was to examine the relationship between anthropometry, physical capacity, and sprint swimming performance in swimmers of both genders aged 12 - 14 years old. Anthropometric characteristics (body height and mass, total upper extremity, hand and foot lengths, chest circumference, certain body breadths, and skinfolds), as well as leg explosiveness (horizontal jump) and arm strength (handgrip strength test) were evaluated in 263 competitive swimmers (178 boys and 85 girls) aged 12 - 14 years. Skeletal age was assessed with the Tanner-Whitehouse method. All variables, except for the ankle and shoulder flexibility as well as the skeletal age, correlated with 100 m freestyle performance in boys (r = - 0.46 to - 0.73, p < 0.01). Using a split-sample approach, upper extremity length, horizontal jump, and grip strength were detected as significant predictors of 100 m freestyle performance in boys (R (2) = 0.59, p < 0.01). In girls, body height, upper extremity and hand length, shoulder flexibility, and horizontal jump were all significantly related to 100 m freestyle time (r = - 0.22 to - 0.31, p < 0.05) but the degree of association was markedly lower than in boys. In addition, only 17 % of the variance in performance was explained by a combination of body height, hand length, and horizontal jump in girls. These results suggest that 100 m freestyle performance can be partially explained by anthropometry and physical capacity tests in young swimmers. The contribution of these factors to sprint swimming performance is different in boys and girls and this requires further research. These findings could be used for male young swimmers' selection.

Central and total adiposity are lower in overweight and obese children with high cardiorespiratory fitness.

OBJECTIVE: To examine the influence of cardiorespiratory fitness on total and truncal fatness in children. It was hypothesised that high cardiorespiratory fitness would result in lower total and central obesity. DESIGN: Observational cohort study. SETTING: Primary and secondary schools in Athens, Greece. SUBJECTS: A total of 1362 healthy children aged 6-13 y (742 boys and 620 girls). METHODS: Anthropometric data (height, body mass, four skinfolds thickness) were collected and per cent body fat was calculated. Body mass index (BMI) sex- and age-specific cutoff points were used for overweight and obesity definition and children were placed in two groups: overweight/obese and nonoverweight. Cardiorespiratory fitness (CRF) was assessed with the endurance shuttle-run test. Participants were grouped into high (upper two quintiles) and low (lower two quintiles) CRF based on age and sex distributions. T-test and Mann-Whitney test were used for comparisons between fit and unfit children within each BMI category. RESULTS: Sum of skinfolds, subscapular and truncal skinfold thickness, BMI and per cent body fat were lower in overweight and obese youths with high CRF in comparison with youths at the same BMI category with low CRF (P<0.01). The beneficial effect of high CRF was also presented in nonoverweight children (P<0.01). The influence of CRF on body composition remained even after correcting body fatness for BMI. CONCLUSIONS: Central and total obesity were lower in overweight and obese children with high CRF. This is the first study to show that a high CRF may reduce the hazards of obesity in children.

Physiological and technical characteristics of elite young basketball players.

AIM: The aim of this study was 2-fold: a) to describe the physiological and technical characteristics of elite young basketball players, and b) to examine the relationship between certain field and laboratory tests among these players. METHODS: Thirteen male players of the junior's Basketball National team (age: 18.5 +/- 0.5 years, mass: 95.5 +/- 8.8 kg, height: 199.5 +/- 6.2 cm, body fat: 11.4 +/- 1.9%, means+/-SD) performed a run to exhaustion on the treadmill, the Wingate test and 2 types of vertical jump. On a separate day, the field tests (control dribble, defensive movement, speed dribble, speed running, shuttle run and dribble shuttle run) were conducted. RESULTS: Maximal oxygen uptake (VO2max) and ventilatory threshold were 51.7 +/- 4.8 ml/kg/min and 77.6 +/- 7.0% VO2max, respectively. Maximum power output was 10.7 +/- 1.3 Watts/kg and mean power (Pmean) 8.0 +/- 0.7 Watts/kg. Counter-movement and squat jump height were 40.1 +/- 3.7 and 39.8 +/- 4.0 cm, respectively. Performance in control dribble (13.70 +/- 0.96 s), speed dribble (4.24 +/- 0.75 s), high intensity shuttle run (27.90 +/- 1.04 s) and dribble shuttle run (29.50 +/- 1.22 s) was correlated with Pmean (r=-0.58, r=-0.62, r=-0.56 and r=-0.73, respectively, p<0.05). Percent body fat was negatively correlated with all the above field tests (r=0.63, r=0.57, r=0.66, r=0.65, respectively, p<0.05). CONCLUSION: These players presented a moderate VO2max and anaerobic power. The significant correlation between Pmean and certain field tests indicates that these tests could be used for the assessment of anaerobic capacity of young basketball players.

Age-related pattern in body composition changes for 18-69 year old women.

AIM: The aim of this study was to describe the age-related pattern in body composition changes for women 18-69 years old. A secondary objective was to assess the relationship between accumulated physical activity and body composition. METHODS: Anthropometric measures, including height, body mass, waist and hip circumference and skinfolds thickness, were taken from 441 healthy women placed in 5 age groups (group 1: 18-29 years, n=71; group 2: 30-39 years, n=69; group 3: 40-49 years, n=159; group 4: 50-59 years, n=92 and group 5: 60-69 years, n=50). Physical activity was assessed with a questionnaire. A 1-way ANOVA, with group 1 as the control and Pearson correlation coefficient were employed for statistical analysis. RESULTS: Body Mass Index, fat mass and waist to hip ratio were all higher in the age groups of 40-49 years and above (21.8+/-0.4 kg/m(2), 14.7+/-0.6 kg, 0.73+/-0.01 for age group 18-29 years and 24.7+/-0.3 kg/m(2), 20.8+/-0.4 kg and 0.76+/-0.01 for age group 40-49 years, respectively; means+/-S.E.M; p<0.01 for all variables). In contrast, fat free mass remained unchanged in the age spectrum studied. Central adiposity, as indicated by the trunk to extremity skinfold ratio, increased after 50-59 years compared with the 18-29 years old group (p<0.01). Body fatness and central adiposity were associated with aging (r=0.16 to 0.46, p<0.05), but not with accumulated physical activity. CONCLUSION: The results of this cross-sectional study showed an age-related increase in body fatness and central adiposity with no detectable change in fat free mass in these women. These changes were not associated with physical activity.

Effect of a carbohydrate-electrolyte drink on endurance capacity during prolonged intermittent high intensity running.

OBJECTIVE: To examine the effect of a carbohydrate-electrolyte solution on endurance capacity during prolonged intermittent running. METHODS: Nine subjects (eight men and one woman) ran to exhaustion on a motorised treadmill on two occasions separated by at least 10 days. After an overnight fast, they performed repeated 15 second bouts of fast running (at 80% Vo2MAX for the first 60 minutes, at 85% Vo2MAX from 60 to 100 minutes of exercise, and finally at 90% Vo2MAX from 100 minutes of exercise until exhaustion), separated by 10 seconds of slow running (at 45% Vo2MAX). On each occasion they drank either a water placebo (P) or a 6.9% carbohydrate-electrolyte (CHO) solution immediately before the run (3 ml/kg body mass) and every 20 minutes thereafter (2 ml/kg body mass). RESULTS: Performance times were not different between the two trials (112.5 (23.3) and 110.2 (21.4) min for the P and CHO trials respectively; mean (SD)). Blood glucose concentration was higher in the CHO trial only at 40 minutes of exercise (4.5 (0.6) v 3.9 (0.3) mmol/1 for the CHO and P trials respectively; p < 0.05), but there was no difference in the total carbohydrate oxidation rates between trials. CONCLUSION: These results suggest that drinking a 6.9% carbohydrate-electrolyte solution during repeated bouts of submaximal intermittent high intensity running does not delay the onset of fatigue.