Age-related deterioration in bone strength among Western humans has been linked with sedentary lifestyles, but the effect remains debatable. We evaluated aging of diaphyseal strength and cortical bone loss in a European Holocene sample of 1881 adult humeri, femora, and tibiae. Diaphyseal aging did not differ between Early and Late Holocene adults, despite their differences in physical activity. Adult diaphyseal aging was accompanied by the disproportionate rate between a faster increase in the medullary area and an absent or marginal increase in the total area. This indicates that subperiosteal apposition did not fully biomechanically compensate for the medullary expansion. Diaphyseal strength remained unchanged through age in female femora and male diaphyses but declined in female humeri and tibiae. We highlight the importance of postnatal growth to compensate for adult medullary expansion. Diaphyseal aging is critical for the upper limbs, as humeri are more sensitive to aging than femora and tibiae.