HIND LIMB PERIMETRY AND MUSCLE WEIGHT IN HIGH INTENSITY INTERVAL TRAINED RATS

Interval‐training can be divided into high‐intensity interval training (HIIT – near maximal efforts) and sprint interval training (supramaximal efforts) [1]. Physiological adaptations to interval‐training are well known, such as increased aerobic capacity (VO2max). Nevertheless, skeletal muscle adaptations, that is clearly dependent on excercise intensity, still need investigation, particularly on HIIT protocols. Male Wistar rats (N=17), weighing 150–200g, were submitted to a HIIT that consisted in a nine week time and intensity incremental protocol starting at 50% Vmax during 20 minutes and ending at 70% Vmax during 60 minutes (Vmax being the maximum velocity, in meters per minute that the animals could individually reach). At the end of the nine‐week protocol, animals were weighed and anesthetized with Sodium Pentobarbital (50mg/kg) and hind limb perimetry was performed below the knee, at mid‐leg level, using a stainless steel Vernier Caliper (300mm – 0.02mm accuracy) and a flexible and inextensible thin cord. Rats were them perfused with buffered saline (PBS 150mM) and had their right and left triceps sural carefully dissected, removed in one piece and weighed using a digital scale Mettler Toledo™ (320g capacity – 0.1 mg readability). Average final body weight was 565 ± 12g. Average leg perimetry was 6.91 ± 0.14cm on the right and 6.81 ± 0.12cm on the left sides with no differences between sides. Average triceps sural weight was 3.61 ± 0.12g on the right and 3.72 ± 0.12 on the left sides, also with no differences between sides. There was no correlation between final body weight and right or left legs perimetry. Also, no correlation was found between final body weight and right or left triceps sural weight. Finally, no correlation was present between leg perimetry and triceps sural weight for both sides. Thus, triceps sural weight was normalized by body weight and the correlation with leg perimetry was again investigated. Still no correlation was found either for right or left sides between the normalized muscle weight and leg perimetry. Despite the absence of positive correlations in the parameters investigated in this study, further histological evaluation of these muscles will be performed since there is still little evidence of the role of exercise intensity in mediating skeletal muscle alterations such as capillary density and mitochondrial content.Support or Funding InformationFAPESP, CNPq, CAPES and FAEPA