Physiotherapy Research Unit, Nuffield Orthopaedic Centre, Oxford University Hospitals NHS Trust, Windmill Rd, Oxford, OX3 7HE, UK.
Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences (NDORMS), University of Oxford, Windmill Rd, Oxford, OX3 7HE, UK.
Osteoporos Int. 2018 Apr;29(4):893-905. doi: 10.1007/s00198-017-4358-8. Epub 2018 Jan 10.
Timed loaded standing (TLS) is a suggested measure of back muscle endurance for people with vertebral osteoporosis. Surface electromyography revealed back muscles work harder and fatigue during TLS. The test end-point and total time were associated with back fatigue. The findings help demonstrate the concurrent validity of the TLS test.
The TLS test is suggested as a measure of back muscle endurance for patients with vertebral osteoporosis. However, to date, no study has demonstrated that TLS does measure back extensor or erector spinae (ES) muscle endurance. We used surface electromyography (sEMG) to investigate the performance of the thoracic ES muscles during TLS.
Thirty-six people with vertebral osteoporosis with a mean age of 71.6 (range 45-86) years participated. sEMG recordings were made of the ES at T3 and T12 bilaterally during quiet standing (QS) and TLS. The relative (%) change in sEMG amplitude between conditions was compared. Fatigue was evaluated by analysing the change in median frequency (MF) of the sEMG signal during TLS, and the correlation between maximal TLS time and rate of MF decline was examined.
Activity in the ES increased significantly during TLS at all electrode locations. During TLS, the MF declined at a mean rate of -24.2% per minute (95% C.I. -26.5 to -21.9%). The MF slope and test time were strongly correlated (r = 0.71), and at test end, the final MF dropped to an average 89% (95% C.I. 85 to 93%) of initial MF. Twenty-eight participants (78%) reported fatigue was the main reason for stopping, and for eight (22%), it was pain.
This study demonstrates that TLS challenges the ES muscles in the thoracic region and results in ES fatigue. Endurance time and the point at which the TLS test ends are strongly related to ES fatigue.
定时站立负荷（TLS）被建议作为椎体骨质疏松症患者背部肌肉耐力的测量方法。表面肌电图显示，TLS 过程中背部肌肉用力更大且更易疲劳。测试终点和总时间与背部疲劳相关。这些发现有助于证明 TLS 测试的同时效度。
TLS 测试被建议作为椎体骨质疏松症患者背部肌肉耐力的测量方法。然而，迄今为止，尚无研究表明 TLS 确实可以测量背部伸肌或竖脊肌（ES）的肌肉耐力。我们使用表面肌电图（sEMG）来研究 TLS 过程中胸段 ES 肌肉的表现。
36 名患有椎体骨质疏松症的患者参与了研究，平均年龄为 71.6 岁（范围为 45-86 岁）。在安静站立（QS）和 TLS 期间，双侧 T3 和 T12 处对 ES 进行 sEMG 记录。比较了两种情况下 sEMG 振幅的相对（%）变化。通过分析 TLS 期间 sEMG 信号的中值频率（MF）的变化来评估疲劳，并且检查了最大 TLS 时间与 MF 下降率之间的相关性。
TLS 过程中，ES 在所有电极位置的活动均显著增加。在 TLS 期间，MF 以每分钟平均-24.2%（95%置信区间-26.5 至-21.9%）的速度下降。MF 斜率和测试时间之间存在强相关性（r=0.71），并且在测试结束时，最终 MF 下降至初始 MF 的平均 89%（95%置信区间 85 至 93%）。28 名参与者（78%）报告疲劳是停止的主要原因，8 名参与者（22%）是疼痛。
本研究表明，TLS 挑战了胸段 ES 肌肉，并导致 ES 疲劳。耐力时间和 TLS 测试结束的时间点与 ES 疲劳密切相关。
