Spriet Lawrence L
Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada.
Sports Med. 2007;37(4-5):332-6. doi: 10.2165/00007256-200737040-00015.
The energy required to run a marathon is mainly provided through oxidative phosphorylation in the mitochondria of the active muscles. Small amounts of energy from substrate phosphorylation are also required during transitions and short periods when running speed is increased. The three inputs for adenosine triphosphate production in the mitochondria include oxygen, free adenosine diphosphate and inorganic phosphate, and reducing equivalents. The reducing equivalents are derived from the metabolism of fat and carbohydrate (CHO), which are mobilised from intramuscular stores and also delivered from adipose tissue and liver, respectively. The metabolism of fat and CHO is tightly controlled at several regulatory sites during marathon running. Slower, recreational runners run at 60-65% maximal oxygen uptake (VO(2max)) for approximately 3:45:00 and faster athletes run at 70-75% for approximately 2:45:00. Both groups rely heavily on fat and CHO fuels. However, elite athletes run marathons at speeds requiring between 80% and 90% VO(2max), and finish in times between 2:05:00 and 2:20:00. They are highly adapted to oxidise fat and must do so during training. However, they compete at such high running speeds, that CHO oxidation (also highly adapted) may be the exclusive source of energy while racing. Further work with elite athletes is needed to examine this possibility.
跑马拉松所需的能量主要通过活动肌肉线粒体中的氧化磷酸化来提供。在跑步速度增加的过渡阶段和短时间内，也需要少量来自底物磷酸化的能量。线粒体中三磷酸腺苷产生的三个输入包括氧气、游离二磷酸腺苷和无机磷酸以及还原当量。还原当量来自脂肪和碳水化合物（CHO）的代谢，它们分别从肌肉内储存中动员出来，也从脂肪组织和肝脏中输送过来。在马拉松跑步过程中，脂肪和CHO的代谢在几个调节位点受到严格控制。速度较慢的业余跑步者以最大摄氧量（VO₂max）的60 - 65%的速度跑大约3小时45分，速度较快的运动员以70 - 75%的速度跑大约2小时45分。两组都严重依赖脂肪和CHO燃料。然而，精英运动员跑马拉松的速度需要达到VO₂max的80%至90%，并在2小时05分至2小时20分之间完成比赛。他们非常适应氧化脂肪，并且在训练期间必须这样做。然而，他们在如此高的跑步速度下比赛，以至于在比赛时CHO氧化（同样高度适应）可能是唯一的能量来源。需要对精英运动员进行进一步的研究来检验这种可能性。
