Ageing is associated with a decline in the complexity of isometric precision pinch grip force and manual dexterity

Introduction The study investigated the time-course of age-related changes in the complexity of isometric precision pinch grip (PG) force and the performance of manual dexterity tasks. Methods Sixty-four individuals across four age groups, younger group (YG; 18 to 30 years), 50 year group (50yr; 50 to 59 years), 60 year group (60yr; 60 to 69 years) and 70 year group (70yr; 70 to 85 years) participated in the study. Participants performed submaximal constant intensity isometric precision PG force control tasks. The complexity of the isometric force signals was assessed using the multiscale entropy analysis (MSE) and detrended fluctuation analysis (DFA). Participants also completed the Purdue Pegboard and Moberg pick-up manual dexterity tests. Results There was a main effect of age group on DFA ( P = 0.005) and MSE ( P < 0.001). The 70 yr group presented with a higher DFA and lower MSE, compared with the YG, 50 yr and 60 yr group (all P < 0.001). The 70 yr group performed worse at the Purdue Pegboard and Moberg pick-up test compared with the YG, 50 yr and 60 yr group (all P < 0.05). Conclusion The current study found that beyond 70 years of age there is a significant decline in isometric precision PG force signal complexity and manual dexterity, when compared with adults under 70 years of age. Collectively, study findings are indicative of preserved fine motor control into the 6 ^th and 7 ^th decades of life, with a functional decline in fine motor control in the 8 ^th decade.