Sport Sciences Department, Laboratory of Motor Control and Learning, Miguel Hernández University of Elche, Elche, Alicante, Spain.
PLoS One. 2024 Sep 19;19(9):e0307949. doi: 10.1371/journal.pone.0307949. eCollection 2024.
Analysis of variability in physiological time series has been shown to be an indicator of the state of the organism. Although there is evidence of the usefulness of analysis of the amount and/or structure of variability (complexity) in cycling actions, there is limited knowledge about its application in resistance exercise. The aim of this study is to find out whether variability in acceleration signals can be an indicator of intensity level in a squat task. For this purpose, an experimental design was developed in which the following participated seventy-two participants (age = 25.7 ± 4.4 years; height = 169.2 ± 9.8 cm; body mass = 67.7 ± 11.2 kg; ratio 1RM/body mass = 1.4 ± 0.3). They performed four repetitions of back squat at loads of 10%, 30%, 50%, 70%, and 90% of 1RM. Acceleration during the exercise was recorded using an inertial measurement unit (IMU) and a force platform. The variability of the movement was then analyzed using Standard Deviation (SD), Detrended Fluctuation Analysis (DFA), Fuzzy Entropy (FuzzyEn), and Sample Entropy (SampEn). For the IMU and for the force platform, significant effects were observed in all variables (p < 0.001). In pairwise comparisons, IMU showed a significant increase in motor complexity with increasing intensity, among most intensities, in DFA, FuzzyEn and SampEn. Differences in force platform were more limited, and only DFA detected differences between most intensities. The results suggest that measures of signal and acceleration variability may be a useful indicator of the relative intensity at which a squat exercise is performed.
对生理时间序列的可变性分析已被证明是机体状态的一个指标。虽然有证据表明分析循环动作的数量和/或结构的可变性（复杂性）是有用的，但关于其在抗阻运动中的应用的知识有限。本研究旨在探讨加速度信号的可变性是否可以作为深蹲任务强度水平的指标。为此，设计了一个实验方案，其中有 72 名参与者（年龄=25.7±4.4 岁；身高=169.2±9.8cm；体重=67.7±11.2kg；1RM/体重比=1.4±0.3）参加了实验。他们以 1RM 的 10%、30%、50%、70%和 90%的负荷完成了 4 次深蹲重复。使用惯性测量单元（IMU）和力量平台记录运动时的加速度。然后使用标准差（SD）、去趋势波动分析（DFA）、模糊熵（FuzzyEn）和样本熵（SampEn）分析运动的可变性。对于 IMU 和力量平台，所有变量均观察到显著影响（p<0.001）。在两两比较中，IMU 在大多数强度下的 DFA、FuzzyEn 和 SampEn 中显示出随强度增加运动复杂性显著增加。力量平台的差异更为有限，仅 DFA 检测到大多数强度之间的差异。结果表明，信号和加速度可变性的测量可能是衡量深蹲运动相对强度的有用指标。
