Failing grip strength in older people is a good biomarker for frailty in all bodily systems and consequently higher mortality levels. Separately, advanced glycation end-products (AGEs) accumulate in the body's tissues with age, and impact a number of important biological processes - so we'd expect to see correlation between rising AGE levels and failing grip strength even if they have no direct link and are completely distinct aspects of age-related degeneration. Here, researchers show that this correlation stretches back into earlier adult life: "Aging is associated with decreased skeletal muscle function. Increased levels of advanced glycation end products (AGEs) in skeletal muscle tissue are observed with advancing age and in diabetes. Although serum AGE level is negatively associated with grip strength in elderly people, it is unknown whether this association is present in adult males. To determine the relationship between AGE accumulation in tissue and muscle strength and power among Japanese adult men. Skin autofluorescence (AF) (a noninvasive method for measuring tissue AGEs), grip strength, and leg extension power were measured in Japanese adult men ... Among Japanese adult men, participants with higher skin AF had lower muscle strength and power, indicating a relationship between AGE accumulation and muscle strength and power. A long-term prospective study is required to clarify the causality." If forced to guess, I'd suggest that the other biochemical and cellular causes of aging have a greater impact than AGEs on muscle strength - but that remains to be established, and we should still be trying to fix everything regardless of the outcome of that investigation.

Link: http://www.ncbi.nlm.nih.gov/pubmed/21188413