Association of change in muscle mass assessed by D₃-creatine dilution with changes in grip strength and walking speed

BACKGROUND: Muscle mass declines with age. However, common assessments used to quantify muscle mass are indirect. The D 3 -creatine (D 3 Cr) dilution method is a direct assessment of muscle mass; however, longitudinal changes have not been examined in relation to changes in other measures of muscle mass, strength, and performance.

METHODS: A convenience sample of 40 men from the Osteoporotic Fractures in Men Study (mean age = 83.3 years, standard deviation = 3.9) underwent repeat assessment of D 3 Cr muscle mass, dual-energy X-ray absorptiometry (DXA) lean mass, grip strength, and walking speed at two time points approximately 1.6 years apart (2014-2016). One-sample t-tests and Pearson correlations were used to examine changes in DXA total body lean mass, DXA appendicular lean mass/height 2 , DXA appendicular lean mass/weight, D 3 Cr muscle mass, D 3 Cr muscle mass/weight, grip strength, walking speed, and weight.

RESULTS: D 3 -creatine muscle mass, D 3 Cr muscle mass/weight, grip strength, and walking speed all significantly declined (all P < 0.01). The change in DXA measures of lean mass was moderately correlated with changes in D 3 Cr muscle mass. There was no significant correlation between the change in DXA measures of lean mass and change in walking speed (all P > 0.05). The change in D 3 Cr muscle mass/weight was moderately correlated with change in walking speed (r = 0.33, P < .05). The change in grip strength was weakly correlated with the change in DXA measures of lean mass and D 3 Cr muscle mass (r = 0.19-0.32).

CONCLUSIONS: The results of our study provide new insights regarding the decline in muscle strength and D 3 Cr muscle mass. The D 3 Cr method may be a feasible tool to measure declines in muscle mass over time.