Tonson Anne, Noble Kayle E, Meyer Ronald A, Rozman Mitchell R, Foley Kevin T, Slade Jill M
1Department of Physiology, Michigan State University, East Lansing, MI; 2Department of Radiology, Michigan State University, East Lansing, MI; and 3Department of Family Medicine, Michigan State University, East Lansing, MI.
Med Sci Sports Exerc. 2017 Aug;49(8):1623-1630. doi: 10.1249/MSS.0000000000001281.
The microvasculature is critical in the control of blood flow. Aging and reduced physical activity (PA) may both decrease microvascular function.
The primary aim was to evaluate the influence of age on microvascular function in adults with similar PA levels. Secondary aims were to assess the reliability of muscle functional magnetic resonance imaging in older adults (OA) and the relationship between PA and microvascular function in OA.
Microvascular blood-oxygen-level dependent (BOLD) responses were measured in young adults (YA, n = 12, mean ± SD age = 21 ± 1 yr old, PA = 239 ± 73 × 10 counts per day) and OA (n = 13, 64 ± 4 yr old, PA = 203 ± 48 × 10 counts per day). Functional magnetic resonance images (3T, echo planar BOLD) of the leg were acquired after brief (1 s) maximal voluntary isometric contractions. The test-retest reliability of BOLD responses and the Pearson correlation between peak BOLD and PA were assessed in a group of OA (OA-r) with a broad range of PA (66 ± 5 yr old, n = 9, PA range = 54 × 10 to 674 × 10 counts per day).
Peak BOLD microvascular responses were reduced for OA compared with YA. OA peak BOLD was 27% lower in the soleus (3.3% ± 0.8% OA vs 4.5% ± 1.4% YA; P = 0.017) and 40% lower in the anterior compartment (1.6% ± 0.6% OA vs 2.7% ± 1.1% YA; P = 0.006). Coefficients of variation were 8.6% and 11.8% for peak BOLD in the soleus and anterior compartment, respectively, with an intraclass correlation of 0.950 for both muscle regions. The correlation between peak BOLD and PA was r ≥ 0.715, P ≤ 0.030.
Aging was associated with reduced microvascular function in leg muscles, independent of PA. The findings also revealed good reliability for BOLD magnetic resonance imaging in OA for the soleus and anterior compartment muscles.
微血管系统在血流控制中至关重要。衰老和体力活动（PA）减少均可能降低微血管功能。
主要目的是评估年龄对PA水平相似的成年人微血管功能的影响。次要目的是评估老年人（OA）肌肉功能磁共振成像的可靠性以及OA中PA与微血管功能之间的关系。
在年轻人（YA，n = 12，平均±标准差年龄 = 21±1岁，PA = 239±73×10次/天）和OA（n = 13，64±4岁，PA = 203±48×10次/天）中测量微血管血氧水平依赖（BOLD）反应。在短暂（1秒）最大自主等长收缩后采集腿部的功能磁共振图像（3T，回波平面BOLD）。在一组PA范围广泛的OA（OA-r，66±5岁，n = 9，PA范围 = 54×10至674×10次/天）中评估BOLD反应的重测可靠性以及峰值BOLD与PA之间的Pearson相关性。
与YA相比，OA峰值BOLD微血管反应降低。比目鱼肌中OA峰值BOLD降低27%（OA为3.3%±0.8%，YA为4.5%±1.4%；P = 0.017），前侧肌间隔中降低40%（OA为1.6%±0.6%，YA为2.7%±1.1%；P = 0.006）。比目鱼肌和前侧肌间隔中峰值BOLD的变异系数分别为8.6%和11.8%，两个肌肉区域的组内相关性均为0.950。峰值BOLD与PA之间的相关性为r≥0.715，P≤0.030。
衰老与腿部肌肉微血管功能降低相关，与PA无关。研究结果还显示，OA中比目鱼肌和前侧肌间隔肌肉的BOLD磁共振成像具有良好的可靠性。
