Dual-site transcranial magnetic stimulation (TMS) is a promising tool to measure supplementary motor area and primary motor cortex (SMA-M1) connectivity in younger and older adults, and could be used to understand the pathophysiology of movement disorders. However, test re-test reliability of dual-site TMS measures of SMA-M1 connectivity has not been established. We examined the reliability of SMA-M1 connectivity using dual-site TMS in two sessions in 30 younger and 30 older adults. For dual-site TMS, a conditioning pulse delivered to SMA (140% of active motor threshold) preceded a test pulse delivered to M1 (intensity that elicited MEPs of ~1 mV) by inter-stimulus intervals (ISI) of 6 ms, 7 ms, and 8 ms. Moderate intraclass correlation coefficients (ICC) were found for SMA-M1 connectivity at an ISI of 7 ms in younger (ICC: 0.69) and older adults (ICC: 0.68). Poor ICCs were found for SMA-M1 connectivity at ISIs of 6 ms and 8 ms in both age groups (ICC range: 0.01–0.40). We report evidence for stable measures of SMA-M1 connectivity at an ISI of 7 ms in both age groups. These findings are foundational for future research developing evidence-based interventions to strengthen SMA-M1 connectivity to improve bilateral motor control in older adults and populations with movement disorders.

双位点经颅磁刺激 (TMS) 是一种很有前途的工具，可用于测量年轻人和老年人的辅助运动区域和初级运动皮层 (SMA-M1) 连接性，并可用于了解运动障碍的病理生理学。然而，SMA-M1 连接的双站点 TMS 措施的测试重新测试可靠性尚未建立。我们在 30 名年轻人和 30 名老年人的两个会话中使用双站点 TMS 检查了 SMA-M1 连接的可靠性。对于双站点 TMS，传递到 SMA（活动运动阈值的 140%）的调节脉冲先于传递到 M1（引起 ~1 mV 的 MEP 的强度）的测试脉冲，其间刺激间隔 (ISI) 为 6 ms, 7毫秒和 8 毫秒。发现 SMA-M1 连通性的中等组内相关系数 (ICC) 的 ISI 为 7 ms 年轻 (ICC: 0. 69）和老年人（ICC：0.68）。在两个年龄组的 6 ms 和 8 ms 的 ISI 中发现 SMA-M1 连接性较差的 ICC（ICC 范围：0.01-0.40）。我们报告了两个年龄组在 7 ms 的 ISI 下稳定测量 SMA-M1 连接的证据。这些发现是未来研究开发循证干预措施以加强 SMA-M1 连接以改善老年人和运动障碍人群的双侧运动控制的基础。