Dos'Santos Thomas, Jones Paul A, Kelly Jonathan, McMahon John J, Comfort Paul, Thomas Christopher
Human Performance Laboratory, University of Salford, Greater Manchester, UK.
Int J Sports Physiol Perform. 2016 Mar;11(2):255-60. doi: 10.1123/ijspp.2015-0222. Epub 2015 Jul 27.
Skeletal-muscle function can be evaluated using force-times curves generated via the isometric midthigh pull (IMTP). Various sampling frequencies (500-1000 Hz) have been used for IMTP assessments; however, no research has investigated the influence of sampling frequency on IMTP kinetics. Therefore, the purpose of this study was to investigate the influence of sampling frequency on kinetic variables during the IMTP, including peak force, time-specific force values (100, 150, and 200 ms), and rate of force development (RFD) at 3 time bands (0-100, 0-150, 0-200 ms).
Academy rugby league players (n = 30, age 17.5 ± 1.1 y, height 1.80 ± 0.06 m, mass 85.4 ± 10.3 kg) performed 3 IMTP trials on a force platform sampling at 2000 Hz, which was subsequently down-sampled to 1500, 1000, and 500 Hz for analysis.
Intraclass correlation coefficients (ICC) and coefficients of variation (CV) demonstrated high within-session reliability for all force and RFD variables across all sampling frequencies (ICC ≥ .80, CV ≤ 10.1%). Repeated-measures analysis of variance revealed no significant differences (P > .05, Cohen d ≤ 0.009) in kinetic variables between sampling frequencies. Overall, high reliability was observed across all sampling frequencies for all kinetic variables, with no significant differences (P > .05) for each kinetic variable across sampling frequencies.
Practitioners and scientists may consider sampling as low as 500 Hz when measuring peak force, time-specific force values, and RFD at predetermined time bands during the IMTP for accurate and reliable data.
可通过等长中大腿拉力（IMTP）产生的力-时间曲线来评估骨骼肌功能。IMTP评估中已使用了各种采样频率（500 - 1000赫兹）；然而，尚无研究调查采样频率对IMTP动力学的影响。因此，本研究的目的是调查采样频率对IMTP期间动力学变量的影响，这些变量包括峰值力、特定时间的力值（100、150和200毫秒）以及3个时间段（0 - 100、0 - 150、0 - 200毫秒）的力发展速率（RFD）。
学院橄榄球联盟运动员（n = 30，年龄17.5 ± 1.1岁，身高1.80 ± 0.06米，体重85.4 ± 10.3千克）在以2000赫兹采样的力平台上进行3次IMTP测试，随后将其下采样至1500、1000和500赫兹进行分析。
组内相关系数（ICC）和变异系数（CV）表明，所有采样频率下所有力和RFD变量在测试期间的可靠性都很高（ICC≥0.80，CV≤10.1%）。重复测量方差分析显示，采样频率之间的动力学变量无显著差异（P＞0.05，科恩d≤0.009）。总体而言，所有采样频率下所有动力学变量的可靠性都很高，各动力学变量在不同采样频率之间无显著差异（P＞0.05）。
在测量IMTP期间预定时间段的峰值力、特定时间的力值和RFD时，从业者和科学家可以考虑低至500赫兹的采样频率，以获取准确可靠的数据。
