Pre-exercise exposure to the treadmill setup changes the cardiovascular and thermoregulatory responses induced by subsequent treadmill running in rats

Abstract

2018) Preexercise exposure to the treadmill setup changes the cardiovascular and thermoregulatory responses induced by subsequent treadmill running in rats, Temperature, 5:2, 109-122, ABSTRACT Different methodological approaches have been used to conduct experiments with rats subjected to treadmill running. Some experimenters have exposed rats to the treadmill setup before initiating exercise to minimize the influences of handling and being placed in an anxiety-inducing environment on the physiological responses to subsequent running. Other experimenters have subjected rats to exercise immediately after placing them on the treadmill. Thus, the present study aimed to evaluate the effects of pre-exercise exposure to the treadmill on physical performance and cardiovascular and thermoregulatory responses during subsequent exercise. Male Wistar rats were subjected to fatiguing incremental-speed exercise at 24 C immediately after being placed on the treadmill or after being exposed to the treadmill for 70 min following removal from their home cages. Core body temperature (T CORE ), tail-skin temperature (T SKIN ), heart rate (HR) and mean arterial pressure (MAP) were recorded throughout the experiments. Rats exposed to the treadmill started exercise with higher T CORE , lower HR and MAP, and unaltered T SKIN . This exposure did not influence performance, but it markedly affected the exercise-induced increases in the four physiological parameters evaluated; for example, the T SKIN increased earlier and at a higher T CORE . Moreover, previous treadmill exposure notably allowed expected exercise-induced changes in cardiovascular parameters to be observed. Collectively, these data indicate that pre-exercise exposure to the treadmill induces important effects on physiological responses during subsequent treadmill running. The present data are particularly relevant for researchers planning experiments involving physical exercise and the recording of physiological parameters in rats.

Supplementation with Saccharomyces boulardii Increases the Maximal Oxygen Consumption and Maximal Aerobic Speed Attained by Rats Subjected to an Incremental-Speed Exercise

“…The maximal aerobic speed (S MAX ) attained during the incremental exercises was calculated according to the equation described by Kunstetter et al [16]: S MAX = S1 + (S2 × t/180 seconds), where S1 is the speed reached in the last completed stage, S2 is the increment in the treadmill speed at each stage, and t is the time spent (in seconds) in the incomplete stage. The external work was calculated in Joules as bm × g × s × sinθ × t, where bm is the animal’s body mass (kg), g is the acceleration of gravity (9.8 m·s −2 ), s is the treadmill speed (m·min −1 ), θ is the angle of treadmill inclination, and t is the time spent in each stage [12,17]. Values for workload were calculated for each stage of incremental exercise, including the incomplete stage, and were then summed; the value obtained after the summation corresponded to the total external work.…”

Rats with higher intrinsic exercise capacities exhibit greater preoptic dopamine levels and greater mechanical and thermoregulatory efficiencies while running

“…The temperature sensor (G2 E-Mitter, ER-4000 model; Mini-Mitter Respironics, Bend, OR) was implanted in the abdominal cavity through an incision in the linea alba of the rectus abdominis. The abdominal sensor was implanted according to a previously described technique (26,35,51). After the surgery, the rats were treated with a subcutaneous analgesic (flunixin meglumine, 2 mg/kg body wt).…”

“…The radio waves emitted by the abdominal sensor were captured by a receiving plate (ER-4000 energizer/receiver; Mini-Mitter Respironics) positioned next to the treadmill. The radio wave frequencies were converted into temperature values by software (Vital View), and the data were stored online (26).…”

Comparative effects of two heat acclimation protocols consisting of high-intensity interval training in the heat on aerobic performance and thermoregulatory responses in exercising rats

“…Immediately after these procedures, the rats were placed on the treadmill, and the exercise was started. As recently reported, the act of subjecting rats to treadmill running without a previous resting period is an adequate and time-saving method for measuring exerciseinduced thermoregulatory responses in this species [24].…”

“…However, the existence of lower resting T COL in heat-acclimated rats should be analysed with caution, considering that rats were quickly manipulated to insert the colonic thermistor and attach the tail-skin thermocouple before placement on the treadmill. As handling and placement on the treadmill represent psychological stressors that increase core temperature in this species [24], we cannot rule out that reduced initial T COL resulted Workload performed by the rats of the three experimental groups during the incremental exercises at pre-and post-interventions (panel A). Change in workload from pre-to post-interventions (panel B).…”