WISE 2005: LBNP Exercise and Flywheel Resistive Exercise as an Effective Countermeasure Combination

Long-term exposure to microgravity can cause a severe musculoskeletal loss and cardiovascular deconditioning in astronauts. In this report, the effectiveness of combined supine treadmill exercise in a lower body negative pressure chamber (LBNPex) and flywheel resistive exercise (Rex) countermeasures was determined to prevent bone loss, reduced aerobic upright exercise capacity and reduced muscle strength. We hypothesized that exercise subjects (EX) would show less decrease in bone mineral density (BMD), peak oxygen consumption (VO2pk) and knee extensor strength (KES) than control subjects (CON). Sixteen healthy female subjects (34 plus or minus 4yrs, 164 plus or minus 6.5cm, 58 plus or minus 5kg; mean plus or minus SD) participated in a 60-d 6 degree head-down tilt bed rest (BR) study after providing written informed consent. Subjects were assigned to one of two groups: a non- exercising CON group or an EX group performing LBNPex 2-4 d/wk and Rex every 3rd-d. VO2pk was measured with a maximal, graded, upright treadmill test performed pre-BR and on 3-d after BR. BMD was assessed pre-BR and 3-d after BR by dual energy x-ray absorptiometry total body DEXA scan (DEXA; HOLOGIC QDR 4500 Elite ). A Cybex dynamometer was employed to measure the isokinetic KES before and 5-d after BR. Two-way repeated measures ANOVA were performed with time as the repeated factor. Statistical significance was set at p less than 0.05. CON experienced a significant decrease in BMD in the trochanter (PRE: 0.670 0.045; POST: 0.646 0.352 g(raised dot) per square centimeter) and in the whole hip (PRE: 0.894 0.059; POST: 0.858 0.057 g(raised dot) per square centimeter). BMD also decreased significantly in EX in the trochanter (PRE: 0.753 plus or minus 0.0617; POST: 0.741 plus or minus 0.061 g(raised dot) per square centimeter) and whole hip (PRE: 0.954 plus or minus 0.067; POST: 0.935 plus or minus 0.069 g(raised dot) per square centimeter). BMD losses were significantly less in EX than in CON subjects. VO2pk was significantly decreased in the CON after BR (PRE: 38.0 plus or minus 4.8; POST: 29.9 plus or minus 4.2 ml(raised dot) per kilogram per minute), but not in the EX (PRE: 39.0 plus or minus 2.0; POST: 37.8 plus or minus 1.9 ml(raised dot) per kilogram per minute). KES was significantly reduced by 30% in CON (PRE: 113 plus or minus 12; POST: 78 plus or minus 8 N-m), but was not different in EX (PRE: 126 plus or minus 25; POST: 115 plus or minus 25 N-m). The combination LBNPex and Rex during 60-d BR protects against cardiovascular and musculoskeletal deconditioning and may be an efficacious countermeasure for prolonged space flight

Female-female aggression is linked to food defence in a poison frog.

Habitat occupancy by territorial animals is expected to depend on the distribution of critical resources. Knowledge on female territoriality is scarce, but it has been suggested as a mechanism to defend limited resources for reproduction. A previous study showed female intrasexual aggression to be associated with territorial behaviour in the strawberry poison frog Oophaga pumilio, a diurnal aposematic species with complex maternal care. Here, we investigate the link between spatial distribution of resources important for reproduction and female distribution and behaviour. We observed focal females in their natural habitat in Costa Rica, and recorded the distribution of ecological predictor variables in a grid system. We used the data for calculating home range and territory sizes and for connecting female habitat use to the distribution of potential resources by computing spatial habitat occupancy models. Even though we found females to occupy large home ranges, they were highly aggressive towards other females only inside a small part of their home range, here termed core area. Among the ecological factors, the sustained abundance of ants (main food item of the frogs), the presence of leaf litter and suitable rearing sites for tadpoles predicted female site occupancy patterns. The number of ants per grid was twice as high in the core areas compared to the rest of the female home ranges. Our results suggest that female spacing behaviour is principally driven by the spatial distribution of its main food resource, but that hiding places (leaf litter) and tadpole-rearing sites also play a role. The defence of areas with sustainably high abundance of ants could be relevant, as egg production and maternal care are energetically highly demanding in this prolonged-breeding species. Regarding the link between resource defence and maternal care, the reproductive strategy of female strawberry poison frogs resembles that of the females of small mammals comprising same-sex competition for food and high investment in producing and rearing young

Supine Treadmill Exercise in Lower Body Negative Pressure Combined with Resistive Exercise Counteracts Bone Loss, Reduced Aerobic Upright Exercise Capacity and Reduced Muscle Strength

Long-term exposure to weightlessness leads to cardiovascular and musculoskeletal deconditioning. In this report, the effectiveness of combined supine treadmill exercise in a lower body negative pressure chamber (LBNPex) and flywheel resistive exercise (Rex) countermeasures was determined to prevent bone loss, reduced aerobic upright exercise capacity and reduced muscle strength. We hypothesized that exercise subjects would show less decrease in bone mineral density (BMD), peak oxygen consumption (VO2pk) and knee extensor strength (KES) than control subjects. Sixteen healthy female subjects participated in a 60-d 6(sup 0) head-down tilt bed rest (BR) study after providing written informed consent. Subjects were assigned to one of two groups: a non-exercising control group CON or an exercise group EX performing LBNPex 2-4 d/wk and Rex every 3rd-d. VO2pk was measured with a maximal, graded, upright treadmill test performed pre-BR and on 3-d after BR. BMD was assessed before and 3-d after BR. Isokinetic KES was measured before and 5-d after BR. Two-way repeated measures ANOVA were performed. Statistical significance was set at p less than 0.05. CON experienced a significant decrease in BMD in the trochanter (PRE: 0.670 plus or minus 0.045; POST: 0.646 plus or minus 0.352 g (raised dot) per square centimeter) and in the whole hip (PRE=0.894 plus or minus 0.059; POST: 0.858 plus or minus 0.057 g (raised dot) per square centimeter). BMD also decreased significantly in EX in the trochanter (PRE: 0.753 plus or minus 0.0617; POST: 0.741 plus or minus 0.061 g (raised dot) per square centimeter) and whole hip (PRE: 0.954 plus or minus 0.067; POST: 0.935 plus or minus 0.069 g (raised dot) per square centimeter). BMD losses were significantly less in EX than in CON subjects. VO2pk was significantly decreased in the CON after BR (PRE: 38.0 plus or minus 4.8; POST: 29.9 plus or minus 4.2 ml (raised dot) per kilogram per minute), but not in the EX (PRE: 39.0 plus or minus 2.0; POST: 37.8 plus or minus 1.9 ml (raised dot) per kilogram per minute). KES was significantly reduced by 30% in Con (PRE: 113 plus or minus 12; POST: 78 plus or minus 8 N-m), but was not different in EX (PRE: 126 plus or minus 25; POST: 115 plus or minus 25 N-m). The combination LBNPex and Rex during 60-d BR protects against cardiovascular and musculoskeletal deconditioning and may be efficacious countermeasure for prolonged space flight