Association between the rate of force development of quadriceps and physical performance in older patients undergoing cardiovascular surgery: a cross-sectional study

AIMS: This study aims to assess the association between the quadriceps rate of force development (RFD) and physical performance in older patients undergoing cardiovascular surgery. METHODS AND RESULTS: A cross-sectional study was conducted with hospitalized patients aged ≥65 years who underwent cardiovascular surgery. Physical performance was evaluated using a Short Physical Performance Battery (SPPB). The 4 m gait speed and time for five repeated chair stands were analysed as secondary outcomes. Ninety-four participants were enrolled (mean age, 75 years; men, 58.5%; median SPPB, 10 points; ≤9 points, 42.6%). Quadriceps isometric strength was measured, and RFD values at two time points (RFD100, 0-100 ms; RFD200, 0-200 ms) were calculated from the slope of the force-time curve. Maximal voluntary contraction (MVC) was also calculated. In all participants, the SPPB was significantly associated with RFD100, RFD200, and MVC. The 4 m gait speed was correlated with RFD100, RFD200, and MVC, and the chair stand test time was negatively correlated with RFD100, RFD200, and MVC. Although these significant associations persisted after adjusting for age, sex, and body mass index or skeletal muscle mass, the association between RFD and physical performance was not significant after adjusting for MVC. Subgroup analysis revealed that the correlation coefficients between RFD and physical performance measures were greater in patients with low muscle mass than in those with preserved muscle mass. Similar results were observed for the secondary outcomes. CONCLUSION: Rate of force development and physical performance were significantly correlated after cardiovascular surgery, especially in those with low muscle mass.