Sit to Stand Muscle Power Is Related to Functional Performance at Baseline and After Supervised Exercise Training in Patients with Lower Extremity Peripheral Artery Disease

Abstract

Patients with peripheral artery disease (PAD) have decreased muscle power contributing to functional limitations. The sit-to-stand (STS) is a validated test to assess muscle power in older individuals; however, it has never been investigated in patients with PAD. We evaluated the relationship between STS muscle power and common disease-related outcomes at baseline and following supervised exercise training (SET) in patients with PAD. This observational study investigated patients with Fontaine stage II. Before and after SET, maximal treadmill walking distance (MWD), functional performance tests (six-min walk, STS, stair climbing, habitual gait speed) and quality of life (SF-36 questionnaire) were assessed. Relative (W.kg-1) STS muscle power was calculated using a validated equation. Multiple regressions models were used. Ninety-five patients with PAD were included (63.1±12.1 years, 67% male). Relative STS muscle power [before: 2.7 W.kg-1 (95%CI 2.5-2.9); after: 3.3 (95%CI 3.1-3.6)], MWD [before: 367.0 m (95%IC 302.4-431.5); after: 598.4 (95%IC 515.6-681.3)], six-min walking distance [before: 418.3 m (95%IC 399.4-437.2); after: 468.8 (95%IC 452.7-484.9)], stair climbing performance [before: 6.8 s (95%IC 6.2-7.4); after: 5.3 (95%IC 4.9-5.7)], habitual gait speed [before: 1.10 m.s-1 (95%IC 1.05-1.14); after: 1.18 (95%IC 1.14-1.22)] significantly increased following SET (P≤.001). Similarly, physical [before: 31.4 (95%IC 29.4-33.3); after: 35.8 (95%IC 33.9-37.7)] and mental [before: 39.5 (95%IC 37.0-42.0); after: 43.1 (95%IC 40.9-45.4)] component summaries of the SF-36 significantly increased (P≤.001). Greater relative STS muscle power at baseline was significantly related to greater baseline treadmill (β≤.380; P≤.002) and functional (β≤.597; P≤.001) performance, and quality of life (β≤.291; P≤.050). Larger increases in relative STS muscle power following SET were associated with greater improvements in functional performance (β≤.419; P≤.009). STS test is a valid clinical tool to monitor overall functional status in patients with symptomatic PAD.