Effects of strength training on physical function: influence of power, strength, and body composition.

The purpose of this study was to determine (a) the effects of strength training (ST) on physical function and (b) the influence of strength, power, muscle volume (MV), and body composition on physical function. Healthy, inactive adults (n = 50) aged 65 years and older underwent strength, power, total body composition (% fat and fat free mass [FFM]), and physical function testing before and after 22 weeks of ST. Physical function testing consisted of tasks designed to mimic common physical activities of daily living (ADL). To improve internal validity of the assessment of mid-thigh intermuscular fat, subcutaneous fat, and knee extensors MV, a 10-week unilateral ST program using the untrained leg as an internal control preceded 12 weeks of whole-body ST. Strength, power, and FFM increased significantly with ST (all p < 0.05), whereas rapid walk, 5 chair stands, and get up and go time decreased significantly with ST in the overall group (all p < 0.05). Women improved significantly in both walking test times (both p < 0.05) but not in the stair climb test, whereas men improved in the stair climb test (p < 0.05) but not in walking test times. Multiple regression analysis revealed the highest R (0.28) for the change in chair stands time, followed by stair climb and usual walk at 0.27 and 0.21, respectively. ST improves performance in functional tasks important for ADLs. Changes in strength, power, and FFM are predictors of ST-induced improvements in these tasks.

Susceptibility genes for gentamicin-induced vestibular dysfunction.

BACKGROUND: Approximately 5% of patients administered gentamicin (GM), an aminoglycoside antibiotic, experience vestibular ototoxicity resulting in balance dysfunction. In the present study, we sought to identify susceptibility genes associated with GM-induced vestibular dysfunction using a case/control design. METHODS: White cases (n=137; 55 men, 82 women) were recruited based on physician-confirmed unilateral or bilateral vestibular dysfunction attributed to GM administration. Controls (n=126; 54 men, 72 women) were healthy, age-matched individuals without vestibular dysfunction or balance impairment. Buccal cell samples were obtained from all subjects and DNA was genotyped for 15 polymorphisms in 9 genes. Candidate genes were identified primarily for their roles in oxidative stress based on predicted mechanisms of gentamicin-induced ototoxicity. Statistical analyses included the multi-dimensionality reduction (MDR) method for identifying gene x gene interactions across multiple candidate genes. RESULTS: Both single gene and MDR analyses revealed the NOS3 (ENOS) p.Glu298Asp polymorphism as significantly associated with GM-induced vestibular dysfunction (both p

Muscle-power quality: does sex or race affect movement velocity in older adults?

To determine sex and race differences in muscle power per unit of muscle contraction, knee-extensor muscle power normalized for knee-extensor muscle volume was measured in 79 middle-aged and older adults (30 men and 49 women, age range 50-85 years). Results revealed that women displayed a 38% faster peak movement velocity than men and African Americans had a 14% lower peak movement velocity than Whites of a similar age when expressed per unit of involved muscle (p < .001). As expected, men exhibited greater knee-extensor strength and peak power per unit of muscle than women, but women had a faster knee- extension movement velocity per unit of muscle than men at the same relative strength level. Moreover, African Americans had greater knee-extensor muscle volume than Whites but exhibited lower knee-extensor strength and lower movement velocity per unit of muscle when tested at the same relative strength levels.

Exposure of children to Deet and other topically applied insect repellents.

BACKGROUND: Use of topical repellents on children is common. Anecdotal reports suggest repellents may be applied inappropriately, but no studies characterizing the actual usage patterns and exposure of children have been reported. METHODS: In the summer of 2002, a cross-sectional survey on the use patterns of repellents on children and possible associated effects was conducted in Maryland campgrounds. Information requested included products used, details of applications, post-application practices, and parents' decision-making process. RESULTS: The study yielded 301 respondents. Deet was the most commonly used active ingredient (83.4%); aerosols were the most common formulation (42.5%). Over a third of subjects (38.9%) treated their children's clothing as well as their skin. Over half of the children did not remove the repellent before going to bed. More than a third of parents failed to read or follow label directions. CONCLUSIONS: This study provides documentation of practices leading to undesirable exposure. Educational outreach to change parents' usage patterns is indicated.