This study examines how power training affects estimated bone strength, revealing that females benefit more than males, especially in the upper limbs (radius). These findings highlight the importance of designing sex-specific exercise programs to enhance bone health. Further research is needed to optimize training duration and address site-specific differences.This study aimed to compare the effects of 12-week of power training (PWT), an explosive form of strength training, on bone microarchitecture, estimated bone strength, and markers in mobility-limited (gait speed < 0.9 m/s) older adults.Fifty-seven older adults (83 ± 5 years) were randomly assigned to either a training group (TRAIN, n = 28, 15 females, 13 males) performing high-intensity PWT or a control group (CTRL, n = 29, 22 females, 7 males) maintaining their usual lifestyle. High-resolution peripheral quantitative computed tomography (HR-pQCT) assessed bone geometry, densities, microarchitecture (e.g. trabecular number (Tb.N) and thickness (Tb.Th)), and estimated bone strength (stiffness and failure load) at the tibia and radius. Blood markers for bone metabolism (PINP and CTX-1) and muscle strength (handgrip and leg press) were also measured.Baseline sex differences showed females having lower stiffness (- 37.5%) and failure load (- 38%) at the radius compared with males. After PWT, females in the TRAIN group exhibited declines in Tb.N (- 4.4%) and improvements in Tb.Th (+ 6.0%), stiffness (+ 2.7%), and failure load (+ 2.4%) at the radius (p < 0.05). A time x group interaction indicated increases in leg press strength for the whole TRAIN group (+ 23%), and within females (+ 29%) and males (+ 19%) (p < 0.001). Baseline handgrip strength correlated with stiffness (r = 0.577) and failure load (r = 0.612) at the radius (p < 0.001). Females in the TRAIN group showed a reduction in PINP (- 25%), while males showed an increase in CTX-1 (+ 18%).A 12-week PWT may enhance estimated bone strength in mobility-limited older adults, especially at sites less accustomed to daily loading (i.e. radius).NCT02051725.