Abstract
BACKGROUND: Evidence pertaining to whether more recent born generations of adults reaching old age have better physical capability than previous generations is scarce and inconclusive. We aimed to investigate birth cohort differences in grip strength. METHODS: The study comprised 5,595 individuals from the Tromsø study waves in 1994/1995, 2007/2008, and 2015/2016. Grip strength (bar) was measured using a Martin vigorimeter, and compared across three birth cohorts of 66- to 84-year-olds (born in: 1910-1929, 1923-1942, 1931-1949), as well as within narrower age bands to ensure nonoverlapping cohorts. Linear regression was applied, adjusted for age, education, smoking, physical activity, height, and weight. RESULTS: Grip strength increased across birth cohorts, and the increase was similar within narrower age bands and across genders. Overall, the increase in sex-adjusted mean grip strength when comparing the first and latest born cohorts, born 21 years apart, was 0.06 bar (95% CI 0.04, 0.07). Higher educational levels, and greater height and weight in the most recent born cohort explained 48% of this difference, while reduced smoking and physical inactivity in more recent born cohorts had little impact. CONCLUSIONS: Our findings suggest higher grip strength in more recent birth cohorts of older Norwegian adults, which can be partly attributed to higher education and greater height. This difference corresponded to a 5-year difference in grip strength; more recent born generations of 80-year-olds, therefore, have similar mean grip strength as 75-year-olds born one generation earlier.