Evangelista Paolo, Rum Lorenzo, Picerno Pietro, Biscarini Andrea
Invictus Academy, 25126 Brescia, Italy.
Department of Engineering, University of Sassari, 07100 Sassari, Italy.
J Funct Morphol Kinesiol. 2025 Aug 20;10(3):322. doi: 10.3390/jfmk10030322.
This study investigates the biomechanics of the bench press and overhead press exercises by modeling the trunk and upper limbs as a kinematic chain of rigid links connected by revolute joints and actuated by single- and two-joint muscles, with motion constrained by the barbell. The aims were to (i) assess the different contributions of shoulder and elbow torques during lifting, (ii) identify the parameters influencing joint loads, (iii) explain the origin of the sticking region, and (iv) validate the model against experimental barbell kinematics. Equations of motion and joint reaction forces were derived analytically in closed form. Dynamic simulations produced vertical barbell velocity profiles under various conditions. A waveform similarity analysis was used to compare simulated profiles with experimental data from maximal bench press trials. The sticking region occurred when shoulder torque dropped below a critical threshold, resulting in a local velocity minimum. Adding elbow torque reduced this dip and shifted the velocity minimum from 38 cm to 23 cm above the chest, although it prolonged the time needed to overcome it. Static analysis revealed that grip width and barbell constraint had a greater effect on shaping the sticking region than muscle architecture parameters. Elbow extensors contributed minimally during early lift phases but became dominant near full extension. Model predictions showed high similarity to experimental data in the pre-sticking (SI = 0.962, = 0.028) and sticking (SI = 0.949, = 0.014) phases, with reduced, non-significant similarity post-sticking (SI = 0.881, > 0.05) due to the assumption of constant torques. The model offers biomechanical insight into how joint torques and barbell constraints shape movement. The findings support training strategies that target shoulder strength early in the lift and elbow strength near lockout to minimize sticking and improve performance.
本研究通过将躯干和上肢建模为通过旋转关节连接的刚性连杆运动链，并由单关节和双关节肌肉驱动，且运动受杠铃约束，来研究卧推和推举练习的生物力学。目的是：（i）评估举重过程中肩部和肘部扭矩的不同贡献；（ii）确定影响关节负荷的参数；（iii）解释停滞区域的成因；（iv）根据实验杠铃运动学验证该模型。运动方程和关节反作用力以封闭形式解析推导得出。动态模拟产生了各种条件下的垂直杠铃速度曲线。使用波形相似性分析将模拟曲线与最大卧推试验的实验数据进行比较。当肩部扭矩降至临界阈值以下时会出现停滞区域，导致局部速度最小值。增加肘部扭矩可减少该下降幅度，并将速度最小值从胸部上方38厘米处移至23厘米处，尽管这延长了克服它所需的时间。静态分析表明，握距和杠铃约束对塑造停滞区域的影响比肌肉结构参数更大。在举重早期阶段，肘部伸肌的贡献最小，但在接近完全伸展时变得占主导地位。模型预测在停滞前阶段（SI = 0.962， = 0.028）和停滞阶段（SI = 0.949， = 0.014）与实验数据具有高度相似性，由于假设扭矩恒定，停滞后期相似性降低且不显著（SI = 0.881， > 0.05）。该模型为关节扭矩和杠铃约束如何塑造运动提供了生物力学见解。研究结果支持在举重早期针对肩部力量以及在接近锁定时针对肘部力量的训练策略，以尽量减少停滞并提高表现。
