Objective: To conduct a per-protocol analysis on thigh muscle volume outcomes from the Spinal Cord Injury and Physical Activity (SCIPA) Switch-On Trial.

Design: Secondary analysis from an assessor-blind randomized, controlled trial.

Setting: Four acute/sub-acute hospitals in Australia and New Zealand.

Participants: 24 adults (1 female) within four weeks of motor complete or incomplete spinal cord injury (SCI)

Intervention: Functional electrical stimulation–assisted cycling (FESC) or passive cycling (PC) 4x/week for 12 weeks.

Outcome Measures: Whole thigh and muscle group volumes calculated from manually segmented MR images.

Results: 19/24 participants completed ≥ twelve weeks of the intervention. Five participants experienced hypertrophy (4 FESC; 1 PC) and eight attenuation of atrophy (<20% volume loss) (3 FESC; 5 PC) in thigh muscle volume. Six participants were non-responders, exhibiting atrophy >20% (3 FESC; 3 PC). Mean (SD) change for FESC was −2.3% (25.3%) and PC was −14.0% (12.3%). After controlling for baseline muscle volumes, a strong significant correlation was found between mean weekly exercise frequency and quadriceps and hamstring volumes (r=6.25, P=0.006), regardless of mode. Average watts was highly correlated to quadriceps volumes only (r=5.92, P=0.01), while total number of sessions was strongly correlated with hamstring volumes only (r=5.91, P=0.01).

Conclusion: This per-protocol analysis of FESC and PC early after SCI reports a partial response in 42% and a beneficial response in 25% of patients who completed 12 weeks intervention, regardless of mode. Strong correlations show a dose–response according to exercise frequency. Characteristics of non-responders are discussed to inform clinical decision-making.

目的：对脊髓损伤和体力活动 (SCIPA) 开启试验的大腿肌肉体积结果进行符合协议分析。

设计：来自评估者盲随机对照试验的二次分析。

地点：澳大利亚和新西兰的四家急性/亚急性医院。

参与者： 24 名成人（1 名女性）在运动完全或不完全脊髓损伤 (SCI) 后 4 周内

干预：功能性电刺激辅助自行车 (FESC) 或被动自行车 (PC) 每周 4 次，持续 12 周。

结果测量：根据手动分割的 MR 图像计算出整个大腿和肌肉群的体积。

结果： 19/24 名参与者完成了≥12 周的干预。5 名参与者大腿肌肉体积出现肥大（4 FESC；1 PC）和 8 次萎缩（<20% 体积损失）（3 FESC；5 PC）。六名参与者是无反应者，表现出萎缩> 20％（3 FESC; 3 PC）。FESC 的平均 (SD) 变化为 -2.3% (25.3%)，PC 为 -14.0% (12.3%)。在控制基线肌肉体积后，发现平均每周运动频率与股四头肌和腘绳肌体积（r=6.25，P=0.006）之间存在强显着相关性，无论模式如何。平均瓦特仅与股四头肌体积高度相关（r=5.92，P=0.01），而训练总次数仅与腘绳肌体积密切相关（r=5.91，P=0.01）。

结论：这项对 SCI 后早期 FESC 和 PC 的符合方案分析报告了 42% 的部分反应和 25% 的完成 12 周干预的患者的有益反应，无论模式如何。强相关性显示根据运动频率的剂量反应。讨论了无反应者的特征，为临床决策提供信息。