Fig. 1

Diagnostic algorithms for the classification of four subgroups determined by sarcopenia and knee OA. People with sarcopenia + knee OA was identified as the coexistence of sarcopenia and radiographic knee OA (Kellgren and Lawrence grade ≥ 2). In the diagnosis of sarcopenia, we used the Asian Working Group criteria [18]. Specifically, sarcopenia was diagnosed if a participant had both low muscle function (slow walking speed [0.8 m/s] or low grip strength [< 26 kg and < 18 kg for men and women, respectively]) and low SMI (< 7.0 kg/m² and < 5.7 kg/m² for men and women, respectively). GS, grip strength; OA, osteoarthritis; SMI, skeletal muscle mass index; WS, walking speed; yrs., years