Regulation of fuel metabolism by preexercise muscle glycogen content and exercise intensity
Regulation of fuel metabolism by preexercise muscle glycogen content and exercise intensity
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DOI：
10.1152/japplphysiol.00421.2004
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发表时间：
2004-12-01
影响因子：
3.3
通讯作者：
Hawley, JA
中科院分区：
文献类型：
--
作者：
Arkinstall, MJ;Bruce, CR;Hawley, JA
迄今为止，研究结果表明，改变运动前肌糖原含量和运动强度对内源性碳水化合物氧化的影响是模棱两可的。调查对象之间的培训状况的差异可能在一定程度上解释了这些不一致的结果。因此，我们确定了运动强度和碳水化合物可用性对同一受试者燃料利用模式的相对影响，这些受试者在运动饮食干预以控制肌糖原含量后，随机进行了四次60分钟的骑行，两次在峰值O-2摄取的45%和两次在峰值O-2摄取的70%（（V）超过点O-2峰值）。运动前高糖原（HG）和低糖原（LG）条件下的肌糖原含量分别为596 +/- 43和202 +/- 21 mmol/ kg干重（P < 0.001）。在运动过程中，在45%（0.85 +/- 0.01 vs. 0.74 +/- 0.01; P < 0.001）和70%（0.90 +/- 0.01 vs. 0.79 +/-0.01; P < 0.001）（V）超过点O-2峰值时，HG的呼吸交换率高于LG。在运动时，全身肌肉糖原氧化对能量消耗的贡献在LG和HG之间存在差异，分别为45%（5 +/- 2 vs. 45 +/- 5%; P < 0.001）和70%（25 +/- 3 vs. 60 +/- 3%; P < 0.001）（V）超过点O-2峰。然而，尽管运动前肌糖原含量及其随后的利用率存在显著差异，但在所有条件下，血糖消失率相似。我们的结论是，在中等训练的个人，肌糖原的可用性（低与高）不影响在低或中等强度的运动过程中的血糖处置率。
To date, the results of studies that have examined the effects of altering preexercise muscle glycogen content and exercise intensity on endogenous carbohydrate oxidation are equivocal. Differences in the training status of subjects between investigations may, in part, explain these inconsistent findings. Accordingly, we determined the relative effects of exercise intensity and carbohydrate availability on patterns of fuel utilization in the same subjects who performed a random order of four 60-min rides, two at 45% and two at 70% of peak O-2 uptake ((V) over dot O-2 peak), after exercise-diet intervention to manipulate muscle glycogen content. Preexercise muscle glycogen content was 596 +/- 43 and 202 +/- 21 mmol/ kg dry mass ( P < 0.001) for high-glycogen (HG) and low-glycogen (LG) conditions, respectively. Respiratory exchange ratio was higher for HG than LG during exercise at both 45% (0.85 +/- 0.01 vs. 0.74 +/- 0.01; P < 0.001) and 70% (0.90 +/- 0.01 vs. 0.79 +/- 0.01; P < 0.001) of (V) over dot O-2 peak. The contribution of whole body muscle glycogen oxidation to energy expenditure differed between LG and HG for exercise at both 45% ( 5 +/- 2 vs. 45 +/- 5%; P < 0.001) and 70% ( 25 +/- 3 vs. 60 +/- 3%; P < 0.001) of (V) over dot O-2 peak. Yet, despite marked differences in preexercise muscle glycogen content and its subsequent utilization, rates of plasma glucose disappearance were similar under all conditions. We conclude that, in moderately trained individuals, muscle glycogen availability ( low vs. high) does not influence rates of plasma glucose disposal during either low- or moderate-intensity exercise.