Exercise and Health Laboratory, CIPER, Faculdade Motricidade Humana, Universidade de Lisboa, Lisbon, Portugal.
Exercise and Health Laboratory, CIPER, Faculdade Motricidade Humana, Universidade de Lisboa, Lisbon, Portugal.
Nutrition. 2024 Jul;123:112414. doi: 10.1016/j.nut.2024.112414. Epub 2024 Feb 29.
Cross-sectional evidence has demonstrated that parallel reactance obtained by bioelectrical impedance analysis (BIA) may be an alternative to the regularly used series of measurements to predict intracellular water (ICW) in athletes. However, we are not aware of any studies that have determined the predictive role or compared the effectiveness of both series and parallel reactance for tracking ICW changes during an athletic season. The main aim of this study was to determine the predictive role and compare both series and parallel reactance (Xc) in tracking ICW during an athletic season.
This longitudinal study analyzed 108 athletes in the preparatory and competitive periods. Using dilution techniques, total body water (TBW) and extracellular water (ECW) were determined and ICW was calculated. Resistance (R), Xc, and impedance (Z) standardized for height were obtained through BIA spectroscopy using a frequency of 50kHz in a series array and then mathematically transformed in a parallel array.
Multiple regression analyses showed that only changes in parallel Xc and capacitance (CAP) (P < 0.05) were predictors of delta ICW during the sports season. In contracts, this was not the case for Xcs. Both changes in R and Z, series and parallel, predicted similarly the changes in ECW and TBW (P < 0.05) in athletes.
Our findings highlight the potential of parallel BIA values to detect changes in body water compartments over a competitive season. These data provide preliminary evidence that changes in parallel Xc/H, and ultimately CAP, represent valid markers of alterations in cell volume during a sports season.
横断面证据表明，生物电阻抗分析（BIA）得到的并联电抗可能是替代常规串联测量来预测运动员细胞内液（ICW）的一种选择。然而，我们不知道有任何研究确定了这两种串联和并联电抗预测作用或比较了它们在跟踪运动员整个赛季 ICW 变化方面的有效性。本研究的主要目的是确定预测作用，并比较串联和并联电抗（Xc）在跟踪运动员整个赛季 ICW 变化方面的作用。
这项纵向研究分析了准备期和比赛期的 108 名运动员。使用稀释技术，确定了总体水（TBW）和细胞外液（ECW），并计算了 ICW。通过 BIA 光谱学使用 50kHz 的频率在串联数组中获得标准化身高的电阻（R）、Xc 和阻抗（Z），然后在并联数组中进行数学转换。
多元回归分析显示，只有并联 Xc 和电容（CAP）的变化（P < 0.05）是运动赛季中 ICW 变化的预测因子。相反，Xcs 则不是。串联和并联的 R 和 Z 的变化都可以很好地预测运动员 ECW 和 TBW 的变化（P < 0.05）。
我们的研究结果强调了并联 BIA 值在检测竞技赛季期间身体水分隔室变化方面的潜力。这些数据初步证明，并联 Xc/H 的变化，最终是 CAP 的变化，代表了运动赛季期间细胞体积变化的有效标志物。
