Manipulation of Muscle Creatine and Glycogen Changes Dual X-ray Absorptiometry Estimates of Body Composition
Manipulation of Muscle Creatine and Glycogen Changes Dual X-ray Absorptiometry Estimates of Body Composition
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DOI：
10.1249/mss.0000000000001174
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发表时间：
2017-05-01
期刊：
影响因子：
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通讯作者：
Burke, Louise M.
中科院分区：
文献类型：
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作者：
Bone, Julia L.;Ross, Megan L.;Burke, Louise M.
标准化双x射线吸收测定（DXA）方案被认为提供了可靠的身体成分测量。目的：我们研究了单独操纵肌糖原和肌酸含量对DXA估计瘦质量的影响。方法：18名训练有素的男性自行车手进行平行组应用肌酸负荷（n = 9） （20 gId(-1)） 5 d负荷；3个gId（-1）维持)或安慰剂（n = 9）与糖原负荷交叉应用（每天12 v 6 gIkg(-1) BM，持续48小时），作为涉及糖原消耗运动方案的大型研究的一部分。通过DXA、生物电阻抗谱和标准活检技术评估体成分、总水、肌糖原和肌酸含量。使用以下效应大小量表评估平均值的变化：90.2小、90.6、中等、91.2大，并与治疗最小有价值效应的阈值进行比较。结果：糖原负荷，无论有无肌酸负荷，都导致瘦体重估计值（平均+/- SD； 3.0% +/- 0.7%和2.0% +/- 0.9%）和腿部瘦体重估计值（3.1% +/- 1.8%和2.6% +/- 1.0%）显著增加。在糖原消耗状态后，腿部瘦质量显著下降（-1.4% +/- 1.6%）。在糖原负荷（2.3% +/- 2.3%）、肌酸负荷（1.4% +/- 1.9%）和联合处理（2.3% +/- 1.1%）后，全身总水量显著增加。结论：肌肉代谢产物和水分含量的变化会改变肌肉蛋白质含量变化最小的时期对瘦质量的DXA估计。在解释dxa对运动员身体成分的估计结果时，需要考虑到这一信息。
Standardizing a dual x-ray absorptiometry (DXA) protocol is thought to provide a reliable measurement of body composition. Purpose: We investigated the effects of manipulating muscle glycogen and creatine content independently and additively on DXA estimates of lean mass. Method: Eighteen well-trained male cyclists undertook a parallel group application of creatine loading (n = 9) (20 gId(-1) for 5 d loading; 3 gId(-1) maintenance) or placebo (n = 9) with crossover application of glycogen loading (12 v 6 gIkg(-1) BM per day for 48 h) as part of a larger study involving a glycogen-depleting exercise protocol. Body composition, total body water, muscle glycogen and creatine content were assessed via DXA, bioelectrical impedance spectroscopy and standard biopsy techniques. Changes in the mean were assessed using the following effect-size scale: 90.2 small, 90.6, moderate, 91.2 large and compared with the threshold for the smallest worthwhile effect of the treatment. Results: Glycogen loading, both with and without creatine loading, resulted in substantial increases in estimates of lean body mass (mean +/- SD; 3.0% +/- 0.7% and 2.0% +/- 0.9%) and leg lean mass (3.1% +/- 1.8% and 2.6% +/- 1.0%) respectively. A substantial decrease in leg lean mass was observed after the glycogen depleting condition (-1.4% +/- 1.6%). Total body water showed substantial increases after glycogen loading (2.3% +/- 2.3%), creatine loading (1.4% +/- 1.9%) and the combined treatment (2.3% +/- 1.1%). Conclusions: Changes in muscle metabolites and water content alter DXA estimates of lean mass during periods in which minimal change in muscle protein mass is likely. This information needs to be considered in interpreting the results of DXA-derived estimates of body composition in athletes.