Norwegian School of Sports Sciences, Norwegian Research Centre for Training and Performance, Post Box 4014, Ullevål Stadion, 0806 Oslo, Norway.
J Appl Physiol (1985). 2010 Dec;109(6):1895-903. doi: 10.1152/japplphysiol.00671.2010. Epub 2010 Oct 14.
Due to the complexity of movement in cross-country skiing (XCS), the muscle activation patterns are not well elucidated. Previous studies have applied surface electromyography (SEMG); however, recent gains in three-dimensional (3D) imaging techniques such as positron emission tomography (PET) have rendered an alternative approach to investigate muscle activation. The purpose of the present study was to examine muscle use during double poling (DP) at two work intensities by use of PET. Eight male subjects performed two 20-min DP bouts on separate days. Work intensity was ∼ 53 and 74% of peak oxygen uptake (Vo(2peak)), respectively. During exercise 188 ± 8 MBq of [(18)F]fluorodeoxyglucose ([(18)F]FDG) was injected, and subsequent to exercise a full-body PET scan was conducted. Regions of interest (ROI) were defined within 15 relevant muscles, and a glucose uptake index (GUI) was determined for all ROIs. The muscles that span the shoulder and elbow joints, the abdominal muscles, and hip flexors displayed the greatest GUI during DP. Glucose uptake did not increase significantly from low to high intensity in most upper body muscles; however, an increased GUI (P < 0.05) was seen for the knee flexor (27%) and extensor muscles (16%), and for abdominal muscles (21%). The present data confirm previous findings that muscles of the upper limb are the primary working muscles in DP. The present data further suggest that when exercise intensity increases, the muscles that span the lumbar spine, hip, and knee joints contribute increasingly. Finally, PET provides a promising alternative or supplement to existing methods to assess muscle activation in complex human movements.
由于越野滑雪（XCS）运动的复杂性，肌肉活动模式尚未得到充分阐明。先前的研究应用了表面肌电图（SEMG）；然而，最近三维（3D）成像技术的进步，如正电子发射断层扫描（PET），为研究肌肉激活提供了一种替代方法。本研究旨在通过 PET 检查两种工作强度下双杖支撑（DP）的肌肉使用情况。8 名男性受试者分别在两天内进行两次 20 分钟的 DP 运动。工作强度分别约为峰值摄氧量（Vo(2peak)）的 53%和 74%。运动过程中注射了 188±8MBq 的 [(18)F]氟脱氧葡萄糖 ([(18)F]FDG)，运动后进行了全身 PET 扫描。在 15 个相关肌肉内定义了感兴趣区域（ROI），并确定了所有 ROI 的葡萄糖摄取指数（GUI）。跨越肩部和肘部关节、腹部肌肉和髋关节屈肌的肌肉在 DP 中显示出最大的 GUI。在大多数上半身肌肉中，从低强度到高强度葡萄糖摄取并没有显著增加；然而，在膝关节屈肌（27%）和伸肌（16%）以及腹部肌肉（21%）中，GUI 增加（P < 0.05）。本数据证实了先前的研究结果，即上肢肌肉是 DP 的主要工作肌肉。本数据进一步表明，当运动强度增加时，跨越腰椎、髋关节和膝关节的肌肉的贡献越来越大。最后，PET 为评估复杂人类运动中的肌肉激活提供了一种有前途的替代或补充方法。
