Intramuscular pressure (IMP) reflects forces produced by a muscle. Age is one of the determinants of skeletal muscle performance. The present study aimed to test whether IMP mirrors known age-related muscular changes. We simultaneously measured the tibialis anterior (TA) IMP, compound muscle action potential (CMAP), and ankle torque in thirteen older adults (60–80 years old) in vivo by applying different stimulation intensities and frequencies. We found significant positive correlations between the stimulation intensity and IMP and CMAP. Increasing stimulation frequency caused ankle torque and IMP to increase. The electromechanical delay (EMD) (36 ms) was longer than the onset of IMP (IMPD) (29 ms). Compared to the previously published data collected from young adults (21–40 years old) in identical conditions, the TA CMAP and IMP of older adults at maximum intensity of stimulation were 23.8% and 39.6% lower, respectively. For different stimulation frequencies, CMAP, IMP, as well as ankle torque of older adults were 20.5%, 24.2%, and 13.2% lower, respectively. Surprisingly, the EMD did not exhibit any difference between young and older adults and the IMPD was consistent with the EMD. Data supporting the hypotheses suggest that IMP measurement is an indicator of muscle performance in older adults.

肌内压 (IMP) 反映肌肉产生的力。年龄是骨骼肌性能的决定因素之一。本研究旨在测试 IMP 是否反映已知的与年龄相关的肌肉变化。我们同时在体内测量了 13 名老年人（60-80 岁）的胫骨前肌 (TA) IMP、复合肌肉动作电位 (CMAP) 和踝关节扭矩通过应用不同的刺激强度和频率。我们发现刺激强度与 IMP 和 CMAP 之间存在显着的正相关。增加刺激频率导致踝关节扭矩和 IMP 增加。机电延迟 (EMD) (36 ms) 比 IMP (IMPD) (29 ms) 的发作时间长。与之前公布的在相同条件下从年轻人（21-40 岁）收集的数据相比，老年人在最大刺激强度下的 TA CMAP 和 IMP 分别降低了 23.8% 和 39.6%。对于不同的刺激频率，老年人的 CMAP、IMP 和踝扭矩分别降低了 20.5%、24.2% 和 13.2%。令人惊讶的是，EMD 在年轻人和老年人之间没有表现出任何差异，并且 IMPD 与 EMD 一致。