Associations between grip strength of parents and their 4-year-old children: findings from the Southampton Women's Survey.

Relationships between birthweight and grip strength throughout the life course suggest that early influences on the growth and development of muscle are important for long-term muscle function. However, little is known about parental influences on children's grip strength. We have explored this in the Southampton Women's Survey, a prospective general population cohort study from before conception through childhood. Grip strength was measured using a Jamar handgrip dynamometer in the mother at 19 weeks' gestation and her partner, and in the child at age 4 years. Pre-pregnancy heights and weights were measured in the mothers; reported weights and measured heights were available for the fathers. Complete data on parents and children were available for 444 trios. In univariable analyses, both parents' grip strengths were significantly associated with that of the child (r = 0.17, P < 0.001 for mothers; r = 0.15, P = 0.002 for fathers). These correlations were similar to that between the grip strength of the mothers and the fathers (r = 0.17, P < 0.001). In the multivariable model, after adjustment for child's height and physical activity, the correlations with the child's grip strength were attenuated, being 0.10 (P = 0.02) and 0.11 (P = 0.01) for mothers' and fathers' grip strength respectively. The findings show that grip strength of each parent is associated with that of the child, indicating that heritable influences and the shared family environment influence the development of muscle strength. This contributes to our understanding of the role of heritable and environmental factors on early muscle growth and development, which are important for muscle function across the life course.