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&#39;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.

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 ...

Assessing Strength Exercise Volume and Its Impact on Insulin Sensitivity in Obesity

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...

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. Others have not reported positive effects12,13,14,15,16,17, and it is unclear why these differences occur.
In a recent narrative review18, it was suggested that strength exercise volume (the number of sets per exercise) is essential to improve insulin sensitivity. For instance, a recent systematic review and meta-analysis demonstrated that sessions composed of 21 sets or more led to a greater improvement in insulin action compared to sessions with fewer than 21 sets19. However, only limited evidence from literature directly supports this notion. For example, higher strength exercise volume (30 sets) improved glucose metabolism more than lower volume (10 sets)20. But it is worth noting that this study implemented circuit-style strength exercises, which limits the comparison to traditional strength exercises. In another study, better insulin sensitivity was observed after a 32-set strength exercise protocol compared to an 8-set protocol21. However, the degree of effort after sets was not reported, and it was presumably greater after the high-volume protocol. This is important because the degree of effort (or proximity to concentric muscular failure, characterized as the inability to continue the set due to failure in the concentric movement of a given repetition) has also been considered an important variable to improve insulin and glucose metabolism18. Thus, the limited available studies on the topic, along with their methodological limitations, preclude further inferences regarding the effects of strength exercise volume on insulin sensitivity.
Another interesting point when discussing strength exercise volume is that it is inherently connected to time commitment. A lower exercise volume, by design, means less time spent in the gym. Among the reasons for not adhering to an exercise program, lack of time is at the top of the list22. Thus, a low-volume strength exercise session that effectively improves insulin sensitivity means less time commitment23 and might result in higher long-term adherence. Furthermore, subjective feelings, such as self-efficacy (self-perception of the ability to accomplish something) and the sensations of pleasure and fun (enjoyment), are also related to exercise adherence24,25,26. It is reasonable to speculate that people might feel more confident and enjoy their exercise experience more when they perform a low-volume strength exercise session that translates into health improvement.
To address the gaps in the literature summarized above, we describe a protocol for a randomized, controlled, crossover, clinical trial with the primary aim of assessing the effects of strength exercise volume on insulin sensitivity in obese individuals. As a secondary aim, we assess the effects of strength exercise volume on subjective feelings (self-efficacy, affection, and enjoyment).
The protocol here describes a randomized, controlled, 3-way, crossover, clinical trial. The chronological sequence of the protocol includes: a pre-participation assessment of health history and anthropometric measures (body mass, height, waist circumference, and body composition); an appointment with the team&#39;s certified nutritionist; a familiarization period with the strength exercises and subjective feelings questionnaires; strength assessment in each exercise; random allocation of the order of the sessions; performance of the 3 sessions (separated by 7-28 days), that is immediately followed by answering the subjective feelings questionnaires; an oral glucose tolerance test (OGTT) the next morning; and data analysis. Figure 1 delineates the protocol design.
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/65478/65478fig01.jpg" /> 
Figure 1: Study design. A flowchart of the trial methodology followed here. 1: Obese (body mass index [BMI] &#62;30 kg/m2; waist circumference &#62;102/88 cm) subjects; 2: Anthropometric assessments and familiarization; random assignment to 3: high-volume strength exercise session (21 sets), 4: low-volume strength exercise session (7 sets), or 5: control day; 6: standard meal following sessions; 7: sleep and overnight fast; 8: oral glucose tolerance test. <a href="https://www.jove.com/files/ftp_upload/65478/65478fig01large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>

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	<tbody>
		<tr>
			<td>dual-energy X-ray absorptiometry</td>
			<td>GE</td>
			<td>DXA, Lunar, iDXA Advanced</td>
			<td>for assessing body composition</td>
		</tr>
		<tr>
			<td>G*Power program&#160;</td>
			<td>Heinrich-Heine-Universit&#228;t D&#252;sseldorf, Germany</td>
			<td>version 3.1.9.6</td>
			<td>for calculating sample size</td>
		</tr>
	</tbody>
</table>

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 &#62;30 kg/m2, central obesity (waist circumference &#62;88 cm and &#62;102 cm for women and men, respectively), and age &#62;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.

Author Spotlight: Exploring the Impact of Reduced Resistance Exercise Volume on Metabolic Health 

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

Our research has been centered on studying how resistance exercise effects glucose metabolism and its potential as a tool to improve overall health. Our primary objective is to provide the general public with practical ways to enhance their metabolic health through resistance exercise. Our research protocol aims to evaluate the impact of varying volumes of resistance exercise on insulin sensitivity and glucose responses.We seek to determine whether reducing amount of exercise can yield similar benefits. To be more specific, we want to find out the extent to which insulin sensitivity improves when the exercise volume is reduced to one third of the original protocol. As most people find it hard to fit exercise into their schedule, reducing exercise volume, and by default, the time spent in the gym could improve people's adherence to exercise.If the metabolic response were comparable between high and low volume resistance exercise, in other words, reducing resistance exercise volume might be time efficient for improving one's metabolic health. Our next steps moving forward, you'll be to study the effects of effort on the improvements of insulin sensitivity in response to resistance exercise. Do we need to push ourselves very hard during a session to observe improvements or can we perform it with less effort and still get better?We're exploring whether reducing resistance exercise volume is time efficient for improving metabolic health, and if can result in long-term improvements. This can lead to more confidence in exercise for those who can spend less time achieving better health.

Figure 2&#160;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...

Watch this Scientific Journal Video about Exploring the Impact of Reduced Resistance Exercise Volume on Metabolic Health at JoVE.com

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

An acute session of strength exercise (SE) ameliorates insulin sensitivity (IS) for several hours; however, the effects of SE volume (i.e., number of ...