Wiesinger Hans-Peter, Rieder Florian, Kösters Alexander, Müller Erich, Seynnes Olivier R
Department of Sport Science and Kinesiology, University of Salzburg Salzburg, Austria.
Department of Sport Science and Kinesiology, University of SalzburgSalzburg, Austria; Institute of Physical Medicine and Rehabilitation, Paracelsus Medical UniversitySalzburg, Austria.
Front Physiol. 2017 Mar 13;8:132. doi: 10.3389/fphys.2017.00132. eCollection 2017.
During running and jumping activities, elastic energy is utilized to enhance muscle mechanical output and efficiency. However, training-induced variations in tendon spring-like properties remain under-investigated. The present work extends earlier findings on sport-specific profiles of tendon stiffness and cross-sectional area to examine whether years of distinct loading patterns are reflected by tendons' ability to store and return energy. Ultrasound scans were performed to examine the morphological features of knee extensor and plantar flexor muscle-tendon units in elite ski jumpers, distance runners, water polo players, and sedentary controls. Tendon strain energy and hysteresis were measured with combined motion capture, ultrasonography, and dynamometry. Apart from the fractional muscle-to-tendon cross-sectional area ratio being lower in the knee extensors of ski jumpers (-31%) and runners (-33%) than in water polo players, no difference in the considered muscle-tendon unit morphological features was observed between groups. Similarly, no significant difference in tendon energy storage or energy return was detected between groups. In contrast, hysteresis was lower in the patellar tendon of ski jumpers (-33%) and runners (-30%) compared to controls, with a similar trend for the Achilles tendon (significant interaction effect and large effect sizes η = 0.2). Normalized to body mass, the recovered strain energy of the patellar tendon was ~50% higher in ski jumpers than in water polo players and controls. For the Achilles tendon, recovered strain energy was ~40% higher in ski jumpers and runners than in controls. Advantageous mechanical properties related to tendon spring-like function are observed in elite athletes whose sport require effective utilization of elastic energy. However, the mechanisms underpinning the better tendon capacity of some athletes to retain elastic energy could not be ascribed to intrinsic or morphological features of the lower limb muscle-tendon unit.
在跑步和跳跃活动中，弹性能量被用来增强肌肉的机械输出和效率。然而，训练引起的肌腱弹簧样特性的变化仍未得到充分研究。本研究扩展了早期关于肌腱刚度和横截面积的运动特异性特征的研究结果，以检验多年不同的负荷模式是否通过肌腱储存和释放能量的能力得以体现。对精英跳台滑雪运动员、长跑运动员、水球运动员和久坐不动的对照组进行了超声扫描，以检查膝伸肌和跖屈肌肌腱单元的形态特征。通过联合运动捕捉、超声检查和测力法测量肌腱应变能和滞后现象。除了跳台滑雪运动员（-31%）和长跑运动员（-33%）的膝伸肌中肌肉与肌腱的横截面积分数比低于水球运动员外，各组之间在所考虑的肌肉肌腱单元形态特征上没有差异。同样，各组之间在肌腱能量储存或能量释放方面也未检测到显著差异。相比之下，跳台滑雪运动员（-33%）和长跑运动员（-30%）的髌腱滞后现象低于对照组，跟腱也有类似趋势（显著交互作用效应，大效应量η = 0.2）。以体重归一化后，跳台滑雪运动员髌腱的恢复应变能比水球运动员和对照组高约50%。对于跟腱，跳台滑雪运动员和长跑运动员的恢复应变能比对照组高约40%。在那些运动需要有效利用弹性能量的精英运动员中，观察到了与肌腱弹簧样功能相关的有利机械性能。然而，一些运动员肌腱保留弹性能量能力更强的潜在机制不能归因于下肢肌肉肌腱单元的内在或形态特征。
