Standardization of Resistance Exercise Training: Effects in Diabetic Ovariectomized Rats

Abstract

This study was carried out with a 3-fold aim: 1) to standardize a maximal load test (MLT) on ladders for prescription of resistance exercise training (RET) in rats, 2) to prescribe moderate-intensity RET based on this MLT and 3) to test the effect of this RET in diabetic ovariectomized rats. Female Wistar rats were divided into control (C), diabetic ovariectomized sedentary (DOS) and trained (DOT) groups. The MLT was standardized with increased load applied to the rat tail for each climb, and blood lactate was measured to identify lactate threshold in C rats. MLT was applied in the 1st, 4th and 8th week of the protocol. After 8 weeks of RET, the arterial pressure was directly recorded. DOS group reduced performance in MLT, body weight, left ventricular, plantar and soleus muscles mass (vs. C). DOT rats showed an improvement in MLT associated with plantar muscle mass increased (vs. C and DOS), with attenuation of hypotension and bradycardia (vs. DOS). In conclusion, the results provide a useful method for determining the maximal load and applying RET in rats. Moreover, this study showed that moderate intensity RET improves hemodynamic status in diabetic ovariectomized rats, thereby reinforcing the role of RET in diabetes management.

Impact of combined exercise training on cardiovascular autonomic control and mortality in diabetic ovariectomized rats

“…All animals showed strength gains during the ladder exercise protocol, probably related to growth over that week and, consequently, favorable changes in muscle properties, resulting in an increased ability to generate force (9). This gain was attenuated in animals in the DOS and DOTA groups, which may be due to STZ-induced skeletal muscle mass loss (30). Note that animals that underwent either resistance (DOTR) or combined (DOTC) exercise training were able to climb with higher loads than animals in the other groups (ES, DOS and DOTA), and exhibited an increase in glycolytic plantar muscle mass, indicating the effectiveness of the protocol based on the maximum load test.…”

“…The resistance exercise training protocol was performed on a ladder that had been adapted for use by rats as previously described in detail (30). One week after STZ injection, the animals were adapted to the act of climbing for 5 consecutive days before the maximal load test and the beginning of the 8-wk training protocol.…”

“…The protocol of resistance exercise training was performed using the normalized value of maximal load for each rat, and was adjusted weekly according to the body weight of the animal. The resistance exercise training protocol was performed for 8 wk, 5 days per week, and at moderate intensity (40 -60% of the maximal load) as recommend for patients with diabetes (30,40), with 15 climbs per session and a 1-min time interval between climbs.…”

“…The arterial cannula was connected to a transducer (Blood Pressure XDCR; Kent Scientific), and arterial pressure (AP) signals were recorded for a 30-min period using a microcomputer equipped with an analog-to-digital converter (CO-DAS, 2 Kz; DATAQ Instruments). The recorded data were analyzed on a beat-to-beat basis to quantify changes in mean arterial pressure (MAP) and heart rate (HR) (13,30,33).…”

“…Spectral power for low-frequency (LF, 0.20 -0.75 Hz) and high-frequency (HF, 0.75-4.0 Hz) bands was calculated by power spectrum density integration within each frequency bandwidth, using a customized routine (MAT-LAB 6.0; Mathworks, Natick, MA) (30).…”