The decline of strength with age has often been attributed to declining muscle mass in older subjects. To investigate factors which might influence changes in strength across the life span, grip strength and muscle mass (as estimated by creatinine excretion and forearm circumference) were measured in 847 healthy volunteers, aged 20-100 years, from the Baltimore Longitudinal Study of Aging. Cross-sectional and longitudinal results concur that grip strength increases into the thirties and declines at an accelerating rate after age 40. However, the grip strength of 48% of subjects less than 40 years old, 29% of individuals 40-59 years old, and 15% of subjects older than 60 did not decline during the average 9-year follow-up. Grip strength is strongly correlated with muscle mass (r = .60, p less than .0001). However, using multiple regression analysis, grip strength is more strongly correlated with age (partial r2 = .38) than muscle mass (partial r2 = .16). Additionally, a residuals analysis demonstrates that younger subjects are stronger and older subjects are weaker than one would predict based on their muscular size. Thus, while strength losses are partially explained by declining muscle mass, there remain other yet undetermined factors beyond declining muscle mass to explain some of the loss of strength seen with aging.

We developed and evaluated scales for grading the prevalence and progression of the individual radiographic features of osteoarthritis (OA) of the hand. Four equally time-spaced hand radiographs from 50 participants in the Baltimore Longitudinal Study of Aging, who were followed for at least 20 years, were read separately and "blindly" by 4 experienced, trained readers. Eleven hand joints were individually assessed for the presence of osteophytes, joint space narrowing, subchondral cysts, subchondral sclerosis, lateral deformity, and cortical collapse, and were also graded using the KellgreniLawrence scale, a global estimate of OA. The intraclass correlation coefficient was used to determine cross-sectional inter-and intrareader reliability. Interreader agreement on OA progression was evaluated using life-table analysis. Each of the grading scales for the individual radiographic features of OA of the hand, except for cysts, were cross-sectionally reliable between readers. Each reader was able to reproduce his original scores almost perfectly when grading the radio-