Are body mass index, waist circumference and waist-to-hip ratio associated with leptin in 90-year-old people?

Data on how body mass index (BMI), waist circumference (WC) and waist-to-hip ratio (WHR) are associated with body fat in the oldest-old people are scarce. The purpose of this study was to examine if BMI, WC or WHR are associated with leptin, a biological surrogate measure of body fat in 90-year-old people. The data comes from the Vitality 90+ Study, a prospective population-based study of people living in Tampere, Finland. BMI, WC, WHR and plasma concentration of leptin were available for 160 women and 54 men aged 90 years. BMI and WC had a strong significant positive association with leptin both in women and in men, but WHR was associated with leptin only in men. In conclusion, based on the circulating level of leptin, BMI and WC, and WHR in men, reflect body fat in 90-year-old people, but WHR seems to be a poor indicator of body fat in 90-year-old women.

Genetic effects in common on maximal walking speed and muscle performance in older women.

The purpose was to examine whether maximal walking speed, maximal isometric knee extensor strength, and leg extensor power share genetic or environmental effects in common. The data was collected from 103 monozygotic and 114 dizygotic female twin pairs aged 63-76 years. Maximal walking speed over 10 m was measured in the laboratory corridor using photocells for timing. Isometric knee extensor strength and leg extensor power were measured using an adjustable dynamometer. The genetic models showed that strength, power, and walking speed had a genetic effect in common which accounted for 52% of the variance in strength, 36% in power, and 34% in walking speed. Strength and power had a non-shared environmental effect in common explaining 13% of variation in strength and 14% in power. The remaining variance was accounted for by trait-specific effects. Some people may be more prone to functional limitation in old age due to their genetic disposition, but this does not rule out that changes in the lifestyle of predisposed subjects may also have a major effect. Approximately half of the variation in each trait was explained by environmental effects, which suggests the importance of the physical activity to improve performance and prevent functional limitation.