Sex Differences in Vitamin D Deficiency and Anthropometric Measurements in School-age Children from Rural Areas in Israel.

BACKGROUND: Vitamin D is essential for skeletal health. Because peak bone mass accrual occurs during childhood and adolescence, vitamin D insufficiency during this period of life could cause adverse health outcomes. OBJECTIVES: To explore the potential sex differences in anthropometric indicators and vitamin D status among primary school-age children. METHODS: A modified food-frequency intake questionnaire was completed by 116 pre-pubertal children (52 girls, 64 boys). Body measurements were recorded and blood was drawn to assess vitamin D status. All children were of Arab-Israeli origin and lived in villages or rural areas in the north-east area of Israel. RESULTS: Prevalence of obesity was higher among girls (34%) compared to boys (21.9%, P = 0.018). All the children were vitamin D insufficient, and 80% were deficient. Plasma vitamin D was significantly higher among boys (12.4 ng/ml) compared to girls (9.1 ng/ml, P < 0.01). A significant negative correlation was found between vitamin D status and weight percentile for girls (r = -0.43, P < 0.05) but not for boys. There was a trend toward a statistically significant inverse correlation between vitamin D status and body fat percent in the girls (r = -0.37, P = 0.07). Sex frameworks are important for the understanding of the determinants of health and the development of effective health promotion programs. CONCLUSIONS: Pre-pubertal girls in Arab villages should be provided with tailor-made nutrition and physical activity programs for promoting health.

Effect of contact and no-contact small-sided games on elite handball players.

This study aimed to investigate the effect of contact (C-SSG) and no-contact (NC-SSG) handball small-sided games (SSGs) on motion patterns and physiological responses of elite handball players. Twelve male handball players performed 10 C-SSG and 10 NC-SSG while being monitored through the heart rate (HR) and rate of perceived exertion (RPE) as physiological responses and time-motion activities profile using video-match analysis. Both game conditions resulted in similar HR responses (P > 0.05), but the NC-SSG led to a higher RPE scores. The time-motion activity analysis featured NC-SSG with a greater amount of walking (855.6 ± 25.1 vs. 690.6 ± 35.2 m) and backward movements (187.5 ± 12.3 vs. 142.5 ± 8.7 m) combined with fast running (232.3 ± 8.5 vs. 159.7 ± 5.7 m) and sprinting (79.5 ± 4.7 vs. 39.7 ± 3.7 m) activities (P < 0.001). Conversely, C-SSG had a higher percentage of jogging and sideway movements associated with greater frequency of jumping (0.87 ± 0.09 vs. 0.31 ± 0.06 nr) and physical contact (1.82 ± 0.55 vs. 0.25 ± 0.03 nr) events (P < 0.001). No between-regimen differences were found for the number of throws (P = 0.745). In addition, the RPE was significantly correlated with fast running relative distances (r = 0.909, P < 0.001) and sprinting relative distances (r = 0.939, P < 0.001). In conclusion, this investigation showed that both C-SSG and NC-SSG in team handball can effectively represent specifically oriented exercises, according to the sport-task and the performance demands.

IGF1 Genetic Polymorphism and the Association between Vitamin D Status and BMI Percentiles in Children.

Both the IGF1 axis and hypovitaminosis D play a role in childhood obesity, either as a cause or a causality. While some studies suggest an interrelation between vitamin D status, IGF1, and obesity, this mechanism remains obscure. The aim of this study, therefore, was to explore associations between four genetic polymorphisms in the IGF1 axis in hypovitaminosis D-related obesity. The study included 116 pre-pubertal Israeli Arab children (52 girls), mean age 9.4 ± 2.6. Serum 25(OH)D was measured and anthropometric measures were obtained. Genomic DNA was extracted from peripheral EDTA-treated anti-coagulated blood using a standard protocol. Genotypes were determined using the Taqman allelic discrimination assay. The IGF genetic score was computed according to the additive genetic score model. A moderate-to-high negative correlation (r = 0.580, p < 0.05) was seen between the vitamin D status and body mass index (BMI) percentile of participants with high GS. Yet, no correlations were seen between vitamin D status and BMI percentile for participants with a low-to-moderate genetic score (GS) (GS ≤ 2). These results suggest that IGF1 genetic scores associated with elevated circulating IGF1 may indicate a tendency toward developing hypovitaminosis D-associated obesity.

Perception of changes in bar velocity in resistance training: Accuracy levels within and between exercises.

Velocity-based training is a method used to monitor resistance-training programs based on repetition velocities measured with tracking devices. Since velocity measuring devices can be expensive and impractical, trainee's perception of changes in velocity (PCV) may be used as a possible substitute. Here, 20 resistance-trained males first completed 1 Repetition Maximum (RM) tests in the bench-press and squat. Then, in three counterbalanced sessions, participants completed four sets of eight repetitions in both exercises using 60%1RM (two-sessions) or 70%1RM. Starting from the second repetition, participants reported their PCV of each repetition as a percentage of the first repetition. Accuracy of PCV was calculated as the difference between PCV and actual changes in velocity measured with a linear-encoder. Three key findings emerged. First, the absolute error in the bench-press and squat was ≈5.8 percentage-points in the second repetition, and increased to 13.2 and 16.7 percentage-points, respectively, by the eighth repetition. Second, participants reduced the absolute error in the second 60%1RM session compared to the first by ≈1.7 in both exercises (p ≤ 0.007). Third, participants were 4.2 times more likely to underestimate changes velocity in the squat compared to the bench-press. The gradual increments in the absolute error suggest that PCV may be better suited for sets of fewer repetitions (e.g., 4-5) and wider velocity-loss threshold ranges (e.g., 5-10%). The reduced absolute error in the second 60%1RM session suggests that PCV accuracy can be improved with practice. The systematic underestimation error in the squat suggests that a correction factor may increase PCV accuracy in this exercise.

The interval-training paradox: Physiological responses vs. subjective rate of perceived exertion.

OBJECTIVE: The purpose of the present study was to compare the physiological and perceived exertion responses of two different interval-training protocols - decreasing- and increasing-distance, matched for total distance, throughout a six-week training period. METHODS: Forty male physical education students (23 ±â€¯1.3 years) were randomly assigned to either the increasing- or decreasing-distance interval-training group (ITG and DTG). The ITG performed increasing-distance interval training (100-200-300-400-500 m) and the DTG performed decreasing-distance interval training (500-400-300-200-100 m), twice a week for each. Heart rate (HR) and rate of perceived exertion (RPE) responses were monitored in each of the six-week training program sessions. RESULTS: Mean HR values were significantly higher (p = .00) in the DTG (181 ±â€¯2.8 bpm) compared with the ITG (163 ±â€¯10.4 bpm). Mean RPE values were significantly higher (p = .00) in the ITG (7.5 ±â€¯0.3 a.u.) compared with the DTG (5.8 ±â€¯0. 6 a.u.). The percent change in RPE responses throughout the six-week training program was significantly greater (p = .00) in the DTG (50% ±â€¯0.7) compared with the ITG (25% ±â€¯0.7). CONCLUSIONS: The findings demonstrated that physiological responses may not necessarily match the participant's perceived exertion, and that in addition to training physical load, a sensation of relief from the achievement is probably a significant factor to be considered during training.

The effect of two different interval-training programmes on physiological and performance indices.

The aim of the present study was to compare the effect of an increasing-distance, interval-training programme and a decreasing-distance, interval-training programme, matched for total distance, on aerobic and anaerobic physiological indices. Forty physical education students were randomly assigned to either the increasing- or decreasing-distance, interval-training group (ITG and DTG), and completed two similar relevant sets of tests before and after six weeks of training. One training programme consisted of increasing-distance interval-training (100-200-300-400-500 m) and the other decreasing-distance interval training (500-400-300-200-100 m). While both training programmes led to a significant improvement in VO2 max (ES = 0.83-1.25), the improvement in the DTG was significantly greater than in the ITG (14.5 ± 3.6 vs. 7.8 ± 3.2%, p < .05). In addition, while both training programmes led to a significant improvement in all anaerobic indices (ES = 0.83-1.63), the improvements in peak power (15.7 ± 7.8 vs. 8.9 ± 4.7), mean power (10.6 ± 5.4 vs. 6.8 ± 4.4), and fatigue index (18.2 ± 10.9 vs. 7.0 ± 14.2) were significantly greater in the DTG compared to the ITG (p < .05). The main finding of the present study was that beyond the significant positive effects of both training programmes on aerobic and anaerobic fitness, the DTG showed significant superiority over the ITG in improving aerobic and anaerobic performance capabilities. Coaches and athletes should therefore be aware that, in spite of identical total work, an interval-training programme might induce different physiological impacts if the order of intervals is not identical.

Longitudinal Study Evaluating Postural Balance of Young Athletes.

Repeated anaerobic conditions during athletic performance may cause general and local fatigue that result in postural balance deficit. Evidence suggests that improved postural balance during athletic training may decrease the risk for fallings and traumatic injuries among athletes. Twenty athletes (12 girls, 8 boys) and 20 controls (12 girls, 8 boys) ages 10-15 years participated in the current study. All athletes were active in an 8-month physical activity program, 3 times per week for 90 min., specific to basketball, soccer, or athletic training. The control children participated in physical education at school only, with no involvement in organized extracurricular sports. All participants were evaluated for postural balance in three assessments over one year (at 4-mo intervals); the Interactive Balance System machine (Tetrax device) was used to assess balance at three test times (pre-, post-, and 10 min) after a session of a repeated sprint anaerobic test, consisting of 12 × 20 m run starting every 20 sec. The athletes had better postural balance than controls. There were different group patterns of change over the sessions; a significant interaction of session and group indicated that postural balance of the groups differed. The contribution of low sway frequencies (F1) and high sway frequencies (F6) differed between the controls and the athletes group. Results suggested that although athletes had better postural balance, improvement should be encouraged during training over the sessions and seasons, with special awareness of the balance deficit that occurs immediately after anaerobic stress and at the end of the season, to decrease the risk of injuries.