Effects of Supraphysiological Doses of Sex Steroids on Wheel Running Activity in Mice.

The regulatory mechanisms of physical activity are postulated to include environmental and biological/genetic factors. In particular, the sex steroids appear to have profound effects on wheel running in rodents. The purpose of this project was to investigate the effects of 17ß-estradiol and testosterone on wheel running distance, duration, and speed in male and female C57BL/6J mice. The mice (N=46) were provided free access to running wheels interfaced with computers to track daily running distance, duration, and speed. Activity was assessed at baseline in intact mice, after surgical gonadectomy, and after replacement with either 17ß-estradiol or testosterone. Upon removal of the gonads, physical activity levels were significantly reduced in both males and females. Distance (10-30% of baseline) and duration (20-47% of baseline) measures were most affected by the loss of endogenous steroids, while running speed (60-77% of baseline) though significantly reduced-decreased by a much lower magnitude. Testosterone replacement fully recovered running distance, duration, and speed to pre-surgical levels in both sexes (100% of baseline). Distance (30-42% of baseline) and duration (43-47% of baseline) were partially recovered by 17ß-estradiol, but not to baseline levels. Speed (100% of baseline) was fully recovered by 17ß-estradiol replacement in males and females. This study suggests that physical activity in mice is affected by endogenous steroids and can be altered by exogenous steroid replacement. The differences in the recovery abilities of 17ß-estradiol and testosterone suggest that both estrogenic and androgenic pathways may be involved to variable degrees in activity regulation.

An evidence-based exercise program implemented in congregate-meal sites.

BACKGROUND: This study examined the feasibility of implementing the EnhanceFitness Program (formerly Lifetime Fitness Program), an evidence-based exercise program, at congregate-meal sites that generally serve low-income older adults. METHODS: A 12-week aerobic and strength training exercise program was held at senior centers 3 times a week. RESULTS: The mean age of the 31 participants was 73.5 years+/-6.7 years (60-86). Participants' compliance with attending the exercise class was 74%. Paired t tests were used to evaluate change after the intervention. Three out of six components of the Senior Fitness Test increased significantly after the exercise intervention (P<.003). Three out of the eight self-reported health concepts of the SF-36 demonstrated significant improvement after the exercise intervention (P<.003). CONCLUSION: These data indicate that an evidence-based exercise program can be successfully implemented in this population.

The effects of aerobic training and nutrition education on functional performance in low socioeconomic older adults.

PURPOSE: To describe the population in terms of risk for disability and compare the effects of a walking intervention and nutrition education intervention on risk modification and functional performance in lower socioeconomic older adults using a randomized controlled study. METHODS: Twenty-six community-dwelling older adults aged 60 and older were randomly assigned to a 16-week walking exercise group or a nutrition education control group. Peak aerobic capacity and physical function were measured at baseline and post intervention. Physical function was measured using the Medical Outcomes Study Short Form Health Survey Physical Function subscale, Short Physical Performance Battery, Physical Performance Test, and Continuous Scale Physical Functional Performance 10 item test (CS-PFP10). RESULTS: Eighty-five percent of the participants were at risk for preclinical disability of which 50% were at risk for moderate disability. The walking exercise group significantly improved in peak aerobic capacity (18.9%), physical function (25%) using the CS-PFP10 compared to the control group. CONCLUSION: These findings highlight the importance of physical activity and indicate that walking, a simple exercise that can be done without specialized exercise leader or equipment can significantly increase peak aerobic capacity and physical function in just 4 months.