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In This Article

  • Summary
  • Abstract
  • Introduction
  • Protocol
  • Representative Results
  • Discussion
  • Acknowledgements
  • Materials
  • References
  • Reprints and Permissions

Summary

This study describes a randomized controlled trial protocol aiming at assessing the acute effects of strength exercise volume on insulin sensitivity in obese individuals.

Abstract

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.

Introduction

Although the chronic effects of strength training on insulin sensitivity have been repeatedly shown1,2,3, even an acute session of strength exercise can improve insulin action for up to 48 h4. This effect has been demonstrated in healthy5,6,7,8, obese 9, older10, insulin-resistant individuals4, and type 2 diabetes mellitus patients11

Protocol

Obtain ethical clearance for the study by submitting the study protocol and informed consent document to the local Institutional Review Board (IRB) or local Research Ethics Committee (REC). The study can only begin after IRB or REC approval. The results presented below are from a pilot study, for which subjects signed a written informed consent before enrollment. After IRB or REC approval, prospectively register the protocol in a public repository, like Clinical Trials (https://clinicaltrials.gov). If your country has a .......

Representative Results

Figure 2 shows representative (from a pilot study) responses for glucose (Figure 2A) and insulin (Figure 2B) during the OGTT. Usually, peaks for glucose and insulin values are observed at 30 min measurement, which is followed by a constant decrease until 120 min measurement. The lower the glucose peak, the better the result, which is indicative of inhibition of hepatic glucose production. The faster the decrease in glucose afte.......

Discussion

This paper detailed the steps for a randomized controlled trial that aimed to assess the effects of strength exercise volume on insulin sensitivity in obese adults. Randomized controlled trials are the best research protocols to establish cause-and-effect of a treatment in an unbiased manner49,50. Specifically, in this study, we will employ a crossover design, which means every subject recruited will perform each condition in a randomized order5.......

Acknowledgements

This study is supported by the National Council for Scientific and Technological Development (CNPQ: Grant#407975/2018-7 and # 402091/2021-3) and by the Minas Gerais State Agency for Research and Development (FAPEMIG: Grant# APQ-00008-22). The funders played no role in this study's design, and do not play any roles in study conduct, interpretation of data, or reporting of results. This study is based at the Federal University of the Jequitinhonha and Mucuri Valleys (Diamantina-MG, Brazil) which provide the equipment and space (DXA, strength training room, strength training equipment, etc.) necessary for conducting the research.

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Materials

NameCompanyCatalog NumberComments
dual-energy X-ray absorptiometryGEDXA, Lunar, iDXA Advancedfor assessing body composition
G*Power program Heinrich-Heine-Universität Düsseldorf, Germanyversion 3.1.9.6for calculating sample size

References

  1. Ismail, A. D., et al. The effect of short-duration resistance training on insulin sensitivity and muscle adaptations in overweight men. Experimental physiology. 104 (4), 540-545 (2019).
  2. Jiahao, L., Jiajin, L., Yifan, L.

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Insulin SensitivityResistance ExerciseStrength ExerciseExercise VolumeObesityRandomized Controlled TrialGlucose MetabolismMetabolic Health

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