PURPOSE To open up new horizons of translational research, we studied the lactate threshold (LT)-dependent physiological responses and adaptations to exercise in rats, highlighting the importance of intensity-specific studies for optimizing exercise prescriptions. LT is physiologically related to the non-invasive gas exchange threshold (GET), and both thresholds are moderate-heavy-intensity boundary indices in determining an effective intensity of aerobic training in humans. While their practical utility is presumed to extend to rats, the actual existence of GET, the thresholds' relations to maximal oxygen consumption (VO2max), and whether aerobic adaptations by training differ around the LT intensity remain uncertain. METHODS This study sought to identify the GET using our previously established rat LT-model by combining the use of a metabolic chamber and the V-slope method and to confirm the thresholds' relations to VO2max. We investigated changes in the thresholds and VO2max following 6 weeks of endurance training at below or above LT intensity. RESULTS GET and LT were significantly correlated, and agreed with high precision, although with a fixed bias. Untrained rats exhibited GET and LT at 56% and 52% of their VO2max, respectively. Endurance training at supra-, but not below-, the LT intensity significantly improved VO2max and both thresholds; however, their %VO2max remained unaltered. CONCLUSIONS GET in rats is identifiable as a threshold associated with LT using the V-slope method. Further, both thresholds can serve as moderate-heavy-intensity boundary indices for the aerobic training of rats. This study advances our understanding of exercise intensity regulation in rats, thereby contributing to the development of a more nuanced and effective model for exercise prescription, with implications for human health and fitness.

中文翻译：

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使用乳酸和气体交换阈值设置大鼠有氧训练的跑步机强度。


目的 为了开辟转化研究的新视野，我们研究了大鼠乳酸阈值 （LT） 依赖性的生理反应和对运动的适应，强调了强度特异性研究对优化运动处方的重要性。LT 在生理学上与无创气体交换阈值 （GET） 相关，这两个阈值都是确定人类有氧训练有效强度的中重强度边界指数。虽然推测它们的实际效用延伸到大鼠，但 GET 的实际存在、阈值与最大耗氧量 （VO2max） 的关系以及训练的有氧适应是否围绕 LT 强度不同仍不确定。方法 本研究试图通过使用代谢室和 V 斜率方法，使用我们先前建立的大鼠 LT 模型来识别 GET，并确认阈值与 VO2max 的关系。我们研究了在低于或高于 LT 强度下进行 6 周耐力训练后阈值和 VO2max 的变化。结果 GET 和 LT 显著相关，并且一致性高，尽管偏倚是固定的。未经训练的大鼠分别表现出 VO2max 的 56% 和 52% 的 GET 和 LT。耐力训练在高于但不低于 LT 强度时显着提高了 VO2max 和两个阈值;然而，他们的 %VO2max 保持不变。结论 大鼠的 GET 使用 V 斜率法可识别为与 LT 相关的阈值。此外，这两个阈值都可以作为大鼠有氧训练的中重强度边界指标。 这项研究促进了我们对大鼠运动强度调节的理解，从而有助于开发一种更细致和有效的运动处方模型，对人类健康和健身具有影响。