Department of Kinesiology, California State University, Fullerton, CA.
Department of Kinesiology, University of Massachusetts, Amherst, MA.
Med Sci Sports Exerc. 2020 Oct;52(10):2189-2197. doi: 10.1249/MSS.0000000000002361.
Prader-Willi Syndrome (PWS) is a form of congenital obesity characterized by excessive body fat, hypotonia, muscle weakness, and physical/cognitive disability. However, the sources of muscle dysfunction and their contribution to mobility are unclear. The purposes of this study were to 1) compare plantar flexor function between adults with and without PWS; and 2) to examine the relationship between plantar flexor function and gait speed in adults with PWS.
Participants included 10 adults with PWS, 10 adults without PWS and with obesity, and 10 adults without PWS and without obesity (matched on age and sex). Plantar flexor function was assessed using isokinetic dynamometry (peak torque [PT], early/late rate of torque development [RTD]), Hoffman reflex (H/M ratio), ultrasound imaging (cross-sectional area [CSA], echo intensity, pennation angle, and fascicle length), and peak propulsive force and plantar flexor moment during gait. Outcomes were compared between groups using one-way MANOVA. Associations between plantar flexor outcomes and gait speed were assessed using Pearson correlation in the PWS group.
Adults with PWS had lower absolute and normalized early RTD, and lower H/M ratio than controls with and without obesity; lower absolute PT and late RTD than controls with obesity (all P < 0.05). Cross-sectional area, propulsive force, and plantarflexor moment were lower, and echo intensity was higher, in adults with PWS compared with controls without obesity (all P < 0.05). Greater absolute PT (r = 0.64), absolute early RTD (r = 0.62), absolute late RTD (r = 0.64), gastrocnemii CSA (r = 0.55), and propulsive force (r = 0.58) were associated with faster gait speed (all P < 0.05).
Adults with PWS have impaired plantar flexor function likely attributable to reduced neuromuscular function and altered muscle morphology, which are associated with slower gait speeds.
普拉德-威利综合征（PWS）是一种先天性肥胖症，其特征为体脂过多、低张力、肌肉无力和身体/认知障碍。然而，肌肉功能障碍的来源及其对运动能力的影响尚不清楚。本研究的目的是：1）比较患有和不患有 PWS 的成年人之间的跖屈肌功能；2）研究患有 PWS 的成年人中跖屈肌功能与步态速度之间的关系。
参与者包括 10 名患有 PWS 的成年人、10 名患有肥胖症但不患有 PWS 的成年人和 10 名不患有肥胖症且不患有 PWS 的成年人（按年龄和性别匹配）。使用等速测力仪（峰值扭矩 [PT]、早期/晚期扭矩发展率 [RTD]）、Hoffman 反射（H/M 比）、超声成像（横截面积 [CSA]、回声强度、羽状角和肌束长度）以及步态时的最大推进力和跖屈肌力矩来评估跖屈肌功能。使用单因素方差分析比较组间差异。在 PWS 组中，使用 Pearson 相关性评估跖屈肌结果与步态速度之间的关系。
与肥胖对照组和非肥胖对照组相比，患有 PWS 的成年人的绝对和归一化早期 RTD 以及 H/M 比值较低；与肥胖对照组相比，绝对 PT 和晚期 RTD 较低（均 P < 0.05）。与非肥胖对照组相比，患有 PWS 的成年人的 CSA、推进力和跖屈肌力矩较小，回声强度较高（均 P < 0.05）。绝对 PT（r = 0.64）、绝对早期 RTD（r = 0.62）、绝对晚期 RTD（r = 0.64）、腓肠肌 CSA（r = 0.55）和推进力（r = 0.58）与更快的步态速度相关（均 P < 0.05）。
患有 PWS 的成年人的跖屈肌功能受损，可能归因于神经肌肉功能降低和肌肉形态改变，这与较慢的步态速度相关。
