Drinkwater Eric J, Galna Brook, McKenna Michael J, Hunt Patrick H, Pyne David B
School of Human Movement Studies, Charles Sturt University, Bathurst, New South Wales, Australia.
J Strength Cond Res. 2007 May;21(2):510-7. doi: 10.1519/R-20406.1.
During the concentric movement of the bench press, there is an initial high-power push after chest contact, immediately followed by a characteristic area of low power, the so-called "sticking region." During high-intensity lifting, a decline in power can result in a failed lift attempt. The purpose of this study was to determine the validity of an optical encoder to measure power and then employ this device to determine power changes during the initial acceleration and sticking region during fatiguing repeated bench press training. Twelve subjects performed a free weight bench press, a Smith Machine back squat, and a Smith Machine 40-kg bench press throw for power validation measures. All barbell movements were simultaneously monitored using cinematography and an optical encoder. Eccentric and concentric mean and peak power were calculated using time and position data derived from each method. Validity of power measures between the video (criterion) and optical encoder scores were evaluated by standard error of the estimate (SEE) and coefficient of variation (CV). Seven subjects then performed 4 sets of 6 free weight bench press repetitions progressively increasing from 85 to 95% of their 6 repetition maximum, with each repetition continually monitored by an optical encoder. The SEE for power ranged from 3.6 to 14.4 W (CV, 1.0-3.0%; correlation, 0.97-1.00). During the free weight bench press training, peak power declined by approximately 55% (p < 0.01) during the initial acceleration phase of the final 2 repetitions of the final set. Although decreases in power of the sticking point were significant (p < 0.01), as early as repetition 5 (-40%) they reached critically low levels in the final 2 repetitions (>-95%). In conclusion, the optical encoder provided valid measures of kinetics during free weight resistance training movements. The decline in power during the initial acceleration phase appears a factor in a failed lift attempt at the sticking point.
在卧推的向心运动过程中，胸部接触杠铃后会有一个初始的高功率推力，紧接着是一个特征性的低功率区域，即所谓的“卡滞区域”。在高强度举重时，功率下降可能导致举重尝试失败。本研究的目的是确定光学编码器测量功率的有效性，然后使用该设备来确定在疲劳的重复卧推训练中初始加速阶段和卡滞区域的功率变化。12名受试者进行了自由重量卧推、史密斯机深蹲以及史密斯机40公斤卧推投掷以进行功率验证测量。所有杠铃运动均使用摄像技术和光学编码器同时进行监测。使用从每种方法获得的时间和位置数据计算离心和向心平均功率及峰值功率。通过估计标准误差（SEE）和变异系数（CV）评估视频（标准）和光学编码器得分之间功率测量的有效性。然后，7名受试者进行4组每组6次的自由重量卧推，重量从其6次重复最大值的85%逐渐增加到95%，每次重复均由光学编码器持续监测。功率的SEE范围为3.6至14.4瓦（CV，1.0 - 3.0%；相关性，0.97 - 1.00）。在自由重量卧推训练期间，在最后一组最后2次重复的初始加速阶段，峰值功率下降了约55%（p < 0.01）。尽管卡滞点的功率下降很显著（p < 0.01），但早在第5次重复时（下降40%），在最后2次重复中就降至极低水平（> - 95%）。总之，光学编码器为自由重量抗阻训练运动中的动力学提供了有效的测量。初始加速阶段的功率下降似乎是卡滞点举重尝试失败的一个因素。
