Monti Elena, Franchi Martino V, Badiali Francesca, Quinlan Jonathan I, Longo Stefano, Narici Marco V
Institute of Physiology, Department of Biomedical Sciences, University of Padua, Padua, Italy.
MRC-ARUK Centre for Musculoskeletal Ageing, University of Nottingham, Derby, United Kingdom.
Front Physiol. 2020 Aug 4;11:946. doi: 10.3389/fphys.2020.00946. eCollection 2020.
To investigate the time-course of changes in knee-extensors muscle mass, architecture and function in response to plyometric training (PLT) performed on a novel training device, the Tramp-Trainer. This machine consists in a trampoline connected to an inclined sledge which allows the performance of repeated jumps while the subject is sitting on a chair.
Eight healthy males (173.6 ± 4.7 cm, 69.7 ± 13.5 kg, 25.3 ± 4.6 years) underwent 6 weeks of bilateral PLT on the tramp-trainer machine. Training was performed three times per week (between 120 and 150 bounces per session). Knee-extensor maximum voluntary torque (MVT) and power, quadriceps femoris (QF) volume (VOL), cross-sectional area from the 20% to the 60% of femur length and CSA , together with vastus lateralis (VL) architecture (fascicle length, Lf, and pennation angle, PA) were assessed after 2, 4, and 6 weeks of PLT.
All results are presented as changes versus baseline values. MVT increased by 17.8% (week 2, < 0.001) and 22.2% (week 4, < 0.01), respectively, and declined to 13.3% ( < 0.05) at week 6 of PLT. Power increased by 18.2% (week 4, < 0.05) and 19.7% (week 6, < 0.05). QF VOL increased by 4.7% (week 4, < 0.05) and 5.8% (week 6, < 0.01); VL VOL increased by 5.2%, ( < 0.05), 8.2%, ( < 0.01), and 9.6% ( < 0.05) at weeks 2, 4, and 6, respectively. An increase in Lf was detected already at wk 2 (2.2%, < 0.05), with further increase at 4 and 6 weeks of PLT (4 and 4.4%, respectively, < 0.01). PA increased by 5.8% ( < 0.05) at week 6. Significant positive correlations were found between CSA and Power ( = 0.46, < 0.001) and between QF VOL and Power ( = 0.44, < 0.024).
PLT induced rapid increases in muscle volume, fascicle length, pennation angle, torque and power in healthy younger adults. Notably, changes in VL VOL and Lf were detectable already after 2 weeks, followed by increases in knee extensors VOL and power from week 4 of PLT. Since the increase in CSA and QF VOL cannot fully explain the increment in muscle power, it is likely that other factors (such as adaptations in neural drive or tendon mechanical properties) may have contributed to such fucntional changes.
研究在一种新型训练设备——蹦床训练器上进行增强式训练（PLT）时，膝伸肌肌肉质量、结构和功能随时间的变化过程。该机器由一个连接到倾斜滑板的蹦床组成，受试者坐在椅子上时可进行重复跳跃。
8名健康男性（身高173.6±4.7厘米，体重69.7±13.5千克，年龄25.3±4.6岁）在蹦床训练器上进行了6周的双侧PLT。每周训练3次（每次训练120至150次弹跳）。在PLT进行2周、4周和6周后，评估膝伸肌最大自主扭矩（MVT）和功率、股四头肌（QF）体积（VOL）、股骨长度20%至60%处的横截面积以及CSA，以及股外侧肌（VL）结构（肌束长度，Lf，和羽状角，PA）。
所有结果均以相对于基线值的变化表示。MVT分别在第2周增加了17.8%（P<0.001）和第4周增加了22.2%（P<0.01），在PLT第6周下降至13.3%（P<0.05）。功率在第4周增加了18.2%（P<0.05），在第6周增加了19.7%（P<0.05）。QF VOL在第4周增加了4.7%（P<0.05），在第6周增加了5.8%（P<0.01）；VL VOL在第2周、第4周和第6周分别增加了5.2%（P<0.05）、8.2%（P<0.01）和9.6%（P<0.05）。在第2周就检测到Lf增加（2.2%，P<0.05），在PLT第4周和第6周进一步增加（分别为4%和4.4%，P<0.01）。PA在第6周增加了5.8%（P<0.05）。CSA与功率之间（r = 0.46，P<0.001）以及QF VOL与功率之间（r = 0.44，P<0.024）发现显著正相关。
PLT可使健康年轻成年人的肌肉体积、肌束长度、羽状角、扭矩和功率迅速增加。值得注意的是，在2周后就可检测到VL VOL和Lf的变化，随后从PLT第4周开始膝伸肌VOL和功率增加。由于CSA和QF VOL的增加不能完全解释肌肉功率的增加，其他因素（如神经驱动的适应性或肌腱力学特性）可能促成了这种功能变化。
