Randomized Controlled Trial to Study the Acute Effects of Strength Exercise on Insulin Sensitivity in Obese Adults.

An acute session of strength exercise (SE) ameliorates insulin sensitivity (IS) for several hours; however, the effects of SE volume (i.e., number of sets) have not been studied thoroughly. Although it is intuitive that some SE is better than none, and more is better than some for the improvement of IS, high-volume sessions might be challenging for diseased populations to complete, especially obese adults, for whom even a brisk walk can be challenging. This protocol details a randomized clinical trial to assess the acute effects of SE on IS in obese adults. The inclusion criteria are body mass index >30 kg/m2, central obesity (waist circumference >88 cm and >102 cm for women and men, respectively), and age >40 years. Participants will be familiarized with the SE (7 exercises targeting major muscle groups) and then will perform three sessions in a randomized order: session 1 - high-volume session (3 sets/exercise); session 2 - low-volume session (1 set/exercise); session 3 - control session (no exercise). Diet will be controlled the day before and on the day of the sessions. Sessions will be completed at night, and an oral glucose tolerance test will be performed the next morning, from which several indexes of IS will be derived, such as the area under the curve (AUC) of glucose and insulin, the Matsuda index, the Cederholm index, the muscle IS index, and the Gutt index. Based on pilot studies, we expect ~15% improvement in IS (insulin AUC, and Matsuda and Cederholm indexes) after the high-volume session, and ~8% improvement after the low-volume session compared to the control session. This study will benefit individuals who find high-volume SE sessions challenging but still aim to improve their IS by investing 1/3 of their time and effort.

High-intensity interval training improves cerebellar antioxidant capacity without affecting cognitive functions in rats.

High-intensity interval training (HIIT) is associated with better physical performance, but there is limited information about the effects of HIIT on redox state of cerebellar tissue, cerebral cortex, and cognition. The aim of this study was to evaluate the effects of HIIT on redox state parameters in cerebellar tissue, cerebral cortex, and cognitive function of Wistar rats. Forty-three young male Wistar rats were housed under controlled environmental conditions with food, and water ad libitum. Animals were assigned to HIIT or Non-trained groups. HIIT protocol was performed during six weeks. Speed was determined through the assesstment of the maximum oxygen consumption (VO2max). HIIT consisted of short bouts (1 min) running on a treadmill at 10° inclination (85-100% of VO2max) with 2 min of active recovery (60% of VO2max, without inclination). Non-trained group was daily exposed to a disconnected treadmill for the same amount of time as HITT group. Both groups were submitted to the open field, and novel object recognition tasks after six weeks. Malondialdehyde concentration (MDA), superoxide dismutase (SOD) activity, and non-enzymatic antioxidant capacity (FRAP) were quantified to determine the redox state. HIIT presented increased levels of MDA, SOD, and FRAP (p < 0.05) in the cerebellar tissue, but no differences were seen in cerebral cortex. These results indicated an improved antioxidant capacity, despite increased MDA levels in the cerebellar tissue. Both groups did not present impairment in locomotor activity, development of anxious behavior or cognitive decline. HIIT enhanced the antioxidant defenses on cerebellar tissue with no deleterious effects on rats' cognition.