Body composition and hydration status changes in male and female open-water swimmers during an ultra-endurance event

Body mass changes during ultra-endurance performances have been described for running, cycling and for swimming in a heated pool. The present field study of 20 male and 11 female open-water swimmers investigated the changes in body composition and hydration status during an ultra-endurance event. Body mass, both estimated fat mass and skeletal muscle mass, haematocrit, plasma sodium concentration ([Na+]) and urine specific gravity were determined. Energy intake, energy expenditure and fluid intake were estimated. Males experienced significant reductions in body mass (-0.5 %) and skeletal muscle mass (-1.1 %) (P < 0.05) during the race compared to females who showed no significant changes with regard to these variables (P > 0.05). Changes in percent body fat, fat mass, and fat-free mass were heterogeneous and did not reach statistical significance (P > 0.05) between gender groups. Fluid intake relative to plasma volume was higher in females than in males during the ultra-endurance event. Compared to males, females' average increase in haematocrit was 3.3 percentage points (pp) higher, urine specific gravity decrease 0.1 pp smaller, and plasma [Na+] 1.3 pp higher. The observed patterns of fluid intake, changes in plasma volume, urine specific gravity, and plasma [Na+] suggest that, particularly in females, a combination of fluid shift from blood vessels to interstitial tissue, facilitated by skeletal muscle damage, as well as exercise-associated hyponatremia had occurred. To summarise, changes in body composition and hydration status are different in male compared to female open-water ultra-endurance swimmers.     

The use of photographs to portray urban ecosystems in six introductory environmental science textbooks

This study examined how photographs in six introductory environmental science texts portrayed the urban environments in which most U.S. students lived. All photographs from all texts were coded to determine whether they depicted urban areas. The urban photographs were then coded to determine what they communicated about the urban environment. The analysis suggested that the texts in this study, though varied in their portrayal of urban ecosystems, did address many of the environmental issues that affected the city. However, urban examples were rarely used to illustrate general ecological concepts that applied to all ecosystems (i.e., biodiversity or evolution). The author contended that “sense of place” theories indicated that more photographs should be dedicated to portraying urban environments as functioning ecosystems. © 2008 Wiley Periodicals, Inc. J Res Sci Teach 45: 1003–1020, 2008