Match internal load in youth elite soccer players is period, playing position and intermittent running capacity dependent

Aims: The aims of this study were: i) to verify whether player internal load (PIL) monitored via heart rate (HR) varies with game-time and playing position; ii) whether intermittent running capacity (IRC) is related to the maintenance of within-match PIL in elite youth (U-15) soccer players. Method: Twenty-one elite soccer players (14±0.5 yrs, 172±7 cm, 63±6 kg) had their heart rate monitored (beats/min) in five matches and were tested twice for IRC (Yo-YoIR2, distance [m]) over a seven-week competitive season. Percentage of maximal heart rate (%HRmax) and time spent (TS%) in five zones (Z1[96%]) were our PIL indexes. Data from three complete games in the same position of each player were analyzed and matches halves, time intervals (T1 to T6), and playing positions (fullbacks, central defenders and forwards [N=5 each], midfielders [N=6]) were compared, and the relationship between IRC and within-match PIL was determined. Results: PIL was higher in 1st (86±3%) than in the 2nd half (84±4%; p<.001). The 2nd half had more TS% in Z1 and Z2 (p<.05). PIL in T4 was the lowest (p<.01), and in T6, it was lower than T1 and T2 (p<.01). Fullbacks and midfielders showed higher PIL and higher TS% in Z4 (p<.05) than the other positional roles. The average IRC correlated with PIL in T6 (r=.56, p<.01) only. Conclusion: In conclusion, the internal load in elite youth (U-15) soccer players varies with game-time and playing position; and their IRC is related to the maintenance of within-match PIL

In sorrow to bring forth children: fertility amidst the plague of HIV

The HIV epidemic is lowering fertility in sub-Saharan Africa. This decline in fertility appears to reflect a fall in the demand for children, and not any adverse physiological consequences of the disease, as it is matched by changes in the expressed preference for children and the use of contraception, and is not significantly correlated with biological markers of sub-fecundity. A fall in fertility lowers dependency ratios and, for a given savings rate, increases future capital per person. These two effects more than offset the loss of prime working age adults and reduced human capital of orphaned children brought by the epidemic, allowing 27 of the nations of sub-Saharan Africa to cumulatively spend US$650 billion, or$650 billionor 5100 per dying adult AIDS victim, on patient care without harming the welfare of future generations. In sum, the behavioral response to the HIV epidemic creates the material resources to fight it