Weinstein R B, Full R J
Department of Integrative Biology, University of California, Berkeley 94720, USA.
Physiol Zool. 1998 May-Jun;71(3):274-84. doi: 10.1086/515927.
Since a decline in temperature decreases aerobic capacity and slows the kinetics of exercise-to-rest transitions in ectotherms, we manipulated body temperature to better understand the performance limits of intermittent locomotion. Distance capacity (i.e., the total distance traveled before fatigue) of the ghost crab, Ocypode quadrata, was determined during acute exposure to 15 degrees C inside a treadmill-respirometer. Instead of exacerbating the near-paralyzing effects of low body temperature resulting from the frequent transitions, intermittent locomotion allowed animals to exceed the performance limits measured during steady-state locomotion. At low temperature, distance capacity for continuous locomotion at 0.04 m s(-1) (83% maximum aerobic speed) was 60 m. When 30 s of exercise at 0.08 m s(-1) (166% maximum aerobic speed) was alternated with 30 s of rest, distance capacity increased to 271 m, 4.5-fold greater than continuous locomotion at the same average speed (83% maximum aerobic speed). A 30-s pause following a 30-s exercise period was sufficient for maintaining low lactate concentrations in muscle and for partial resynthesis of arginine phosphate. A greater dependency on nonoxidative metabolism due to slowed oxygen uptake kinetics at low temperature resulted in a decreased duration of the critical exercise period, which increased performance relative to that measured at higher temperatures (30 s at 15 degrees C vs. 120 s at 24 degrees C). Despite the ghost crab's limited aerobic capacity at 15 degrees C, distance capacity during intermittent locomotion at low temperature can be comparable to that of a crab moving continuously at a body temperature 10 degrees C warmer. While endurance capacity is generally correlated with maximum aerobic speed, we have demonstrated that both locomotor behavior and body temperature must be considered when characterizing performance limits.
由于温度下降会降低变温动物的有氧能力，并减缓运动到休息转换的动力学过程，我们通过控制体温来更好地理解间歇性运动的性能极限。在跑步机 - 呼吸计内急性暴露于15摄氏度的条件下，测定了四角招潮蟹（Ocypode quadrata）的距离能力（即疲劳前行进的总距离）。间歇性运动并没有加剧因频繁转换而导致的低温近乎麻痹的影响，反而使动物能够超越稳态运动时测得的性能极限。在低温下，以0.04米/秒（最大有氧速度的83%）持续运动的距离能力为60米。当以0.08米/秒（最大有氧速度的166%）运动30秒与休息30秒交替进行时，距离能力增加到271米，比以相同平均速度（最大有氧速度的83%）持续运动时高出4.5倍。在30秒的运动期后进行30秒的暂停足以维持肌肉中低乳酸浓度，并使磷酸精氨酸部分重新合成。由于低温下氧气摄取动力学减缓，对非氧化代谢的依赖性增加，导致关键运动期的持续时间缩短，这相对于在较高温度下测得的性能有所提高（15摄氏度下为30秒，24摄氏度下为120秒）。尽管四角招潮蟹在15摄氏度时有氧能力有限，但低温下间歇性运动的距离能力可与体温高10摄氏度时持续运动的螃蟹相媲美。虽然耐力能力通常与最大有氧速度相关，但我们已经证明，在描述性能极限时，必须同时考虑运动行为和体温。
