Effects of an anterior cruciate ligament injury prevention program on performance in adolescent female soccer players.

Female soccer players are three times more likely to suffer a non-contact anterior cruciate ligament (ACL) tear compared with male soccer players. Several ACL injury prevention programs have been developed and are used to reduce injury risk. However, to date there is limited information on how such programs affect physical performance. The aim of this randomized controlled study was to investigate the effects of the Prevent Injury Enhance Performance (PEP) program in adolescent female soccer players. Four soccer teams were randomly assigned to an intervention (PEP) or control (CON) group and assessed at baseline, 6 weeks, and 12 weeks on linear sprinting, countermovement jump (CMJ), and two agility tests. A mixed model factorial ANOVA with repeated measures was used to assess for treatment effects on the dependent variables. Improvements in 27.3 and 36.6 m sprint times (<0.10 s) were evident during the first 6 weeks for PEP, but reverted back to baseline values by 12 weeks; there were no changes for 9.1 or 18.2 m sprint times in either group. There was no change in the CMJ height for PEP; however, there was a decrement at 6 and 12 weeks compared with baseline in CON. Performance on the Illinois and pro-agility tests declined in both groups. Our findings demonstrate that improvements in linear sprint performance were small and transient in adolescent female soccer players, and that there was no benefit of the PEP program on CMJ or agility performance. ACL injury prevention programs designed as a structured warm-up routine seem to lack the necessary stimulus to enhance athletic performance.

Effects of high altitude and water deprivation on arginine vasopressin release in men.

High-altitude exposure changes the distribution of body water and electrolytes. Arginine vasopressin (AVP) may influence these alterations. The purpose of this study was to examine the effect of a 24-h water deprivation trial (WDT) on AVP release after differing altitude exposures. Seven healthy males (age 22 +/- 1 yr, height 176 +/- 2 cm, mass 75.3 +/- 1.8 kg) completed three WDTs: at sea level (SL), after acute altitude exposure (2 days) to 4,300 m (AA), and after prolonged altitude exposure (20 days) to 4,300 m (PA). Body mass, standing and supine blood pressures, plasma osmolality (Posm), and plasma AVP (PAVP) were measured at 0, 12, 16, and 24 h of each WDT. Urine volume was measured at each void throughout testing. Baseline Posm increased from SL to altitude (SL 291.7 +/- 0.8 mosmol/kgH2O, AA 299.6 +/- 2.2 mosmol/kgH2O, PA 302.3 +/- 1.5 mosmol/kgH2O, P < 0.05); however, baseline PAVP measurements were similar. Despite similar Posm values, the maximal PAVP response during the WDT (at 16 h) was greater at altitude than at SL (SL 1.7 +/- 0.5 pg/ml, AA 6.4 +/- 0.7 pg/ml, PA 8.7 +/- 0.9 pg/ml, P < 0.05). In conclusion, hypoxia appeared to alter AVP regulation by raising the osmotic threshold and increasing AVP responsiveness above that threshold.

Effects of exercise in diabetic rats before and during gestation on maternal and neonatal outcomes.

This study was designed to evaluate the effects of chronic endurance training on glucose and lipid homeostasis in diabetic mothers and their offspring. Female Sprague-Dawley rats were rendered diabetic (>20 mmol/l glucose) by streptozotocin and subdivided into three treatments (n = 10/group): exercise (20 m/min; 0% grade; 1 h/day; 5 days/wk) before and during gestation (EE), exercise before gestation with cessation on conception (ES), and sedentary before and during gestation (SS). Response of dams to a preconception and third trimester glucose tolerance test, litter number (EE = ES = SS = 3), and average litter size (EE = 9.7 +/- 1.5; ES = 9.0 +/- 1.5; SS = 8.3 +/- 0.3) did not differ among groups. Number of offspring remaining viable was significantly different among groups (EE = 17; ES = 0; SS = 14). Response to a glucose challenge and fasting glucose and insulin were different between the EE and SS pups. Exercise before and during gestation did not reduce the viability of offspring. Cessation of exercise during early pregnancy negatively affected offspring viability.

Energy expenditure during submaximal walking with Exerstriders.

This study was designed to determine whether Exerstriding, a modified form of walking using walking sticks (Exerstriders), resulted in an augmented cardiorespiratory response and a greater energy expenditure than when walking without Exerstriders. Female subjects (23.6 +/- 4.0 yr; 58.5 +/- 5.5 kg) completed two randomly assigned trials of treadmill walking (6.7 km.h-1; 0% grade; 30 min.) with (Exerstrider (E)) and without Exerstriders (Control (C)). Mean oxygen consumption (E = 20.5 +/- 1.2 ml.min-1.kg-1; C = 18.3 +/- 2.5 ml.min-1.kg-1), heart rate (E = 132.5 +/- 19.2 beats.min-1; C = 121.5 +/- 21.2 beats.min-1) and respiratory exchange ratio (E = .82 +/- .03; C = .78 +/- .04) were significantly greater (P < or = 0.05) while walking with Exerstriders. Total caloric expenditure was also significantly greater during the Exerstrider condition (E = 173.7 +/- 20.9 kcal; C = 140.7 +/- 27.2 kcal.). In contrast, the rating of perceived exertion did not differ significantly between the two conditions. These data suggest that Exerstriding provides a means to increase caloric expenditure during submaximal walking, a factor that may be of critical importance in enhancing health benefits--such as improved body composition and aerobic capacity--typically associated with walking programs.