Bone is a dynamic tissue that adapts its stiffness and strength to the habitual loading environment. Muscles attach to bone and the largest loads experienced by bone come from voluntary muscle contractions. The objective of this study was to quantify the relationship between functional measures of muscle loading (i.e., joint moments, isometric muscle strength, and physical activity questionnaire scores) and bone stiffness, strength, and volumetric bone mineral density (vBMD). Moderate correlations were observed between peak joint moments and bone stiffness (r=0.480, p=0.032) and strength (r=0.490, p=0.028). No relationship was observed between joint moments and vBMD, or between any bone measurements and muscle strength or physical activity. These findings suggest that muscle loading may influence bone stiffness and strength through alterations in bone quality rather than quantity, and that the functional relationship between muscle and bone may be best reflected by habitual measures of skeletal loading.