The secular trend for grip strength in Canada and the United States.

Worldwide, body weight has risen dramatically in recent decades, raising the question of whether there were concomitant changes in physical fitness. Past research with children and adolescents has shown that body weight and grip strength are positively correlated. Therefore, it was predicted that grip strength had increased on average in children and adolescents over the past four or five decades. To test this prediction, relevant data were extracted from 18 studies for males (N = 5676 in total) and 17 studies for females (N = 5489 in total). The studies were conducted in Canada and the United States from about 1966 on, with participants' ages ranging from 6 through 19 years. Weighted least squares regression analyses showed that grip strength was significantly predicted by age but not by country. Male grip strength decreased significantly over the period covered, but the change was very small, accounting for far less than 1% of the variance in male grip strength. Discussion focuses on potential explanations for why grip strength did not change over time as predicted.