Monitoring chronic physical stress using biomarkers, performance protocols and mathematical functions to identify physiological adaptations in rats

Abstract

This study was undertaken to characterize the effects of monotonous training at lactate minimum (LM) intensity on aerobic and anaerobic performances; glycogen concentrations in the soleus muscle, the gastrocnemius muscle and the liver; and creatine kinase (CK), free fatty acids and glucose concentrations in rats. The rats were separated into trained (n ¼ 10), baseline (n ¼ 10) and sedentary (n ¼ 10) groups. The trained group was submitted to the following: 60 min/day, 6 day/week and intensity equivalent to LM during the 12-week training period. The training volume was reduced after four weeks according to a sigmoid function. The total CK (U/L) increased in the trained group after 12 weeks (742.0 + 158.5) in comparison with the baseline (319.6 + 40.2) and the sedentary (261.6 + 42.2) groups. Free fatty acids and glycogen stores (liver, soleus muscle and gastrocnemius muscle) increased after 12 weeks of monotonous training but aerobic and anaerobic performances were unchanged in relation to the sedentary group. The monotonous training at LM increased the level of energy substrates, unchanged aerobic performance, reduced anaerobic capacity and increased the serum CK concentration; however, the rats did not achieve the predicted training volume. Rats have been used extensively as an experimental model to study physiological adaptations to physical stress. 1 -6 Exercise paradigms applied to rats can provide information concerning the metabolic alterations promoted by disease, diet, surgery, drugs and other interventions in relation to the preservation of homeostasis.7 -12 However, the metabolic effects of exercise on these animals are frequently questioned due to lack of information about and criteria for the intensity imposed during exercise training. 13In an attempt to establish the intensity of exercise using appropriate protocols for rats, our group has developed studies to evaluate the aerobic/anaerobic transition, which is also referred to as the lactate threshold.

Short and Long Term Effects of High-Intensity Interval Training on Hormones, Metabolites, Antioxidant System, Glycogen Concentration, and Aerobic Performance Adaptations in Rats

“…HIIT has been an important protocol of signaling to a multitude of target cells allowing aerobic adaptations during short term further than traditional endurance training (de Araujo et al, 2013a). Some studies reported that endurance training in rats may attenuate the natural loss, but not increase the aerobic capacity in comparison to baseline (de Araujo et al, 2012, 2013b).…”

Interval Versus Continuous Training With Identical Workload: Physiological and Aerobic Capacity Adaptations

“…de Araujo et al (2013b) reported that monotonous training in swimming rats at intensity correspondent to 100 % of AT, decreased the training volume and increased serum CK concentration; suggesting that exercise at constant intensity cannot be applied in longterm training to improve the aerobic performance. Although these authors found glycogen supercompensation, the stores were not mobilized to increase the aerobic performance and to sustain the estimated volume.…”

The Lactate Minimum Test: Concept, Methodological Aspects and Insights for Future Investigations in Human and Animal Models

“…Regarding the Wistar rats, the LMT is extensively used in different contexts as a valuable tool to estimate the aerobic capacity. In addition, authors have used the time to exhaustion (i.e., T lim), obtained during the second swim effort at 13% of the body mass (phase 1; de Araujo et al, 2007), as an anaerobic metabolism indicator (de Araujo et al, 2012, 2013a,b). Thus, the LMT is considered a complete evaluation for Wistar rats, forasmuch as in one aerobic and anaerobic test results can be achieved.…”