Kanaley J A, Mottram C D, Scanlon P D, Jensen M D
Endocrine Research Unit, Mayo Clinic, Rochester, Minnesota 55905, USA.
J Appl Physiol (1985). 1995 Aug;79(2):439-47. doi: 10.1152/jappl.1995.79.2.439.
During running exercise above the lactate threshold (LT), it is unknown whether free fatty acid (FFA) mobilization can meet the energy demands for fatty acid oxidation. This study was performed to determine whether FFA availability is reduced during running exercise above compared with below the LT and to assess whether the level of endurance training influences FFA mobilization. Twelve marathon runners and 12 moderately trained runners ran at a workload that was either above or below their individual LT. Fatty acid oxidation (indirect calorimetry) and FFA release ([1-14C]palmitate) were measured at baseline, throughout exercise, and at recovery. The plasma FFA rate of appearance increased during exercise in both groups; running above or below the LT, but the total FFA availability for 30 min of exercise was greater (P < 0.01) in the below LT group (marathon, 23 +/- 2 mmol; moderate, 21 +/- 2 mmol) than in the above LT group (18 +/- 3 and 13 +/- 3 mmol, respectively). Total fatty acid oxidation (indirect calorimetry) greatly exceeded circulating FFA availability, regardless of training or exercise group (P < 0.01). No statistically significant exercise intensity or training differences in fatty acid oxidation were found (above LT: marathon, 71 +/- 12, moderate, 64 +/- 17 mmol/30 min; below LT: marathon 91 +/- 12, moderate, 60 +/- 5 mmol/30 min). In conclusion, during exercise above or below LT, circulating FFA cannot meet the oxidative needs and intramuscular triglyceride stores must be utilized. Further marathon training does not enhance effective adipose tissue lipolysis during exercise compared with moderate endurance training.
在高于乳酸阈值（LT）的跑步运动中，游离脂肪酸（FFA）的动员是否能够满足脂肪酸氧化的能量需求尚不清楚。本研究旨在确定与低于LT的跑步运动相比，高于LT的跑步运动期间FFA的可用性是否降低，并评估耐力训练水平是否会影响FFA的动员。12名马拉松跑者和12名中度训练的跑者在高于或低于各自LT的工作负荷下跑步。在基线、运动全程和恢复过程中测量脂肪酸氧化（间接量热法）和FFA释放（[1-14C]棕榈酸）。两组运动期间血浆FFA的出现率均增加；无论跑步强度高于还是低于LT，但在低于LT组（马拉松跑者，23±2 mmol；中度训练跑者，21±2 mmol）中，30分钟运动的总FFA可用性比高于LT组（分别为18±3和13±3 mmol）更大（P<0.01）。无论训练或运动组如何，总脂肪酸氧化（间接量热法）大大超过循环FFA的可用性（P<0.01）。未发现脂肪酸氧化在运动强度或训练方面有统计学上的显著差异（高于LT：马拉松跑者，71±12；中度训练跑者，64±17 mmol/30分钟；低于LT：马拉松跑者，91±12；中度训练跑者，60±5 mmol/30分钟）。总之，在高于或低于LT的运动中，循环FFA无法满足氧化需求，必须利用肌肉内甘油三酯储备。与中度耐力训练相比，进一步的马拉松训练并不能增强运动期间有效的脂肪组织脂解作用。
