Geor R J, McCutcheon L J, Shen H
Department of Clinical Studies, Ontario Veterinary College, University of Guelph, Canada.
Equine Vet J Suppl. 1999 Jul(30):311-7. doi: 10.1111/j.2042-3306.1999.tb05240.x.
The objectives of this study were to determine the effects of 10 consecutive days of moderate-intensity training on 1) the muscular metabolic response to exercise at 100% of the pre-training maximum rate of oxygen consumption (VO2max); and 2) mitochondrial enzyme markers (citrate synthase, CS; succinate dehydrogenase, SDH; 3-hydroxy-acyl-CoA dehydrogenase, HAD) of oxidative capacity in middle gluteal muscle. Six mature, unfit Thoroughbred horses completed both incremental (for determination of VO2max) and high-intensity exercise protocols before (HI1) and after (HI2) training. Training consisted of 10 consecutive days of running at 55% VO2max for 60 min per day (13-14 km/day). For the HI, horses completed a 10 min warm-up, followed by exercise at 100% of pre-training VO2max (mean speed 9.8 m/s) until fatigue. Training resulted in an 8.9% increases in VO2max (Pre: 142 +/- 4 ml/kg bwt/min; Post: 155 +/- 4 ml/kg bwt/min) and a 24% increase in run time to fatigue during HI. Whereas VO2 during HI was not altered by training, peak values for VCO2 and R were significantly lower following training. Compared to HI1, there was a 45% reduction in the net rate of muscle glycogenolysis during HI2. Peak (end exercise) values for plasma and muscle lactate concentrations decreased by 22 and 23%, respectively, after training. Training also attenuated the exercise-associated increase in plasma norepinephrine, but there was no effect on plasma epinephrine concentrations. Maximal activities of CS, SDH, and HAD were unaltered by training. We conclude that 10 days of moderate-intensity exercise results in decreases in muscle glycogenolysis and anaerobic metabolism during high-intensity exercise at the same absolute workload. Furthermore, development of measurable increases in mitochondrial oxidative potential may not be required for expression of these metabolic adaptations in early training.
本研究的目的是确定连续10天的中等强度训练对以下两方面的影响：1）肌肉对以训练前最大耗氧率（VO2max）的100%进行运动的代谢反应；2）臀中肌氧化能力的线粒体酶标志物（柠檬酸合酶，CS；琥珀酸脱氢酶，SDH；3-羟基酰基辅酶A脱氢酶，HAD）。六匹成熟、不健康的纯种马在训练前（HI1）和训练后（HI2）完成了递增运动（用于测定VO2max）和高强度运动方案。训练包括连续10天以55%VO2max的强度每天跑步60分钟（13 - 14公里/天）。对于高强度运动，马匹先进行10分钟的热身，然后以训练前VO2max的100%进行运动（平均速度9.8米/秒）直至疲劳。训练使VO2max增加了8.9%（训练前：142±4毫升/千克体重/分钟；训练后：155±4毫升/千克体重/分钟），并使高强度运动期间的疲劳跑步时间增加了24%。虽然训练并未改变高强度运动期间的VO2，但训练后VCO2和R的峰值显著降低。与HI1相比，HI2期间肌肉糖原分解的净速率降低了45%。训练后，血浆和肌肉乳酸浓度的峰值（运动结束时）分别下降了22%和23%。训练还减弱了运动相关的血浆去甲肾上腺素增加，但对血浆肾上腺素浓度没有影响。CS、SDH和HAD的最大活性并未因训练而改变。我们得出结论，10天的中等强度运动可导致在相同绝对工作量的高强度运动期间肌肉糖原分解和无氧代谢减少。此外，在早期训练中，这些代谢适应的表达可能不需要线粒体氧化潜能有可测量的增加。
