Utah State University.
University of Otago.
Int J Sport Nutr Exerc Metab. 2021 May 1;31(3):244-249. doi: 10.1123/ijsnem.2020-0240. Epub 2021 Jan 28.
Ultrasound is an appealing tool to assess body composition, combining the portability of a field method with the accuracy of a laboratory method. However, unlike other body composition methods, the effect of hydration status on validity is unknown. This study evaluated the impact of acute hydration changes on ultrasound measurements of subcutaneous fat thickness and estimates of body fat percentage. In a crossover design, 11 adults (27.1 ± 10.5 years) completed dehydration and hyperhydration trials to alter body mass by approximately ±2%. Dehydration was achieved via humid heat (40 °C, 60% relative humidity) with exercise, whereas hyperhydration was via ingestion of lightly salted water. Ultrasound measurements were taken at 11 body sites before and after each treatment. Participants lost 1.56 ± 0.58 kg (-2.0 ± 0.6%) during the dehydration trial and gained 0.90 ± 0.21 kg (1.2 ± 0.2%) during the hyperhydration trial even after urination. The sum of fat thicknesses as measured by ultrasound differed by <0.90 mm across trials (p = .588), and ultrasound estimates of body fat percentage differed by <0.5% body fat. Ultrasound measures of subcutaneous adipose tissue were unaffected by acute changes in hydration status by extents beyond which are rare and overtly self-correcting, suggesting that this method provides reliable and robust body composition results even when subjects are not euhydrated.
超声是一种评估身体成分的有吸引力的工具，它结合了现场方法的便携性和实验室方法的准确性。然而，与其他身体成分测量方法不同，水合状态对其有效性的影响尚不清楚。本研究评估了急性水合变化对超声测量皮下脂肪厚度和体脂百分比估计值的影响。在一项交叉设计中，11 名成年人（27.1 ± 10.5 岁）完成了脱水和水合过度试验，使体重分别约增加或减少±2%。脱水通过湿热（40°C，60%相对湿度）和运动来实现，而水合过度通过摄入轻度加盐的水来实现。在每个处理前后，在 11 个身体部位进行超声测量。参与者在脱水试验中损失了 1.56 ± 0.58 公斤（-2.0 ± 0.6%），在水合过度试验中增加了 0.90 ± 0.21 公斤（1.2 ± 0.2%），即使在排尿后也是如此。超声测量的脂肪厚度在不同试验中相差<0.90 毫米（p=0.588），超声估计的体脂百分比相差<0.5%体脂。急性水合状态变化对皮下脂肪组织的超声测量没有影响，其程度超出了罕见和明显的自我纠正范围，这表明即使受试者没有水合，该方法也能提供可靠和稳健的身体成分结果。
