Background Grip strength is a well-established predictor of various chronic conditions and all-cause mortality. Body weight and physical activity (PA) are considered potential determinants of muscle strength. This study aimed to investigate gender-specific associations of baseline obesity and physical inactivity with long-term changes in grip strength among middle-aged and older European adults.

Methods Data from the Survey of Health, Ageing and Retirement in Europe 2004–2015 which was conducted in 12 countries were analysed. Grip strength was repeatedly measured at five follow-up visits with average 2-year intervals. Obesity and physical inactivity at baseline were primary exposures. Generalised estimated equations stratified by gender were fitted.

Results This study included 8616 males and 10 088 females with a median follow-up of 9.42 years. Significant interactions between obesity and time with grip strength were identified in both males (χ² _interaction=16.65, p = 0.002) and females (χ² _interaction=10.80, p = 0.029). No significant interaction between physical inactivity and time with grip strength was identified in males (χ² _interaction=9.42, p = 0.051) or females (χ² _interaction=5.62, p = 0.230). Those who were less physically active at baseline had weaker grip strength from the beginning at baseline (β = −2.753, p < 0.001 for males and β = −1.529, p < 0.001 for females) to Visit 6 (β = −2.794, p < 0.001 for males and β = −1.550, p < 0.001 for females). Further combined analysis suggested a trend that exposure to both obesity and physical inactivity was related to the fastest decline rate of grip strength.

Conclusions This study provides the additional evidence that PA and obesity prevention earlier in life play an important role in maintaining grip strength during ageing.