assessing the effects of strength exercise on insulin sensitivity in obese individuals

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

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>

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.

Watch this Scientific Journal Video about Assessing the Effects of Strength Exercise on Insulin Sensitivity in Obese Individuals at JoVE.com

Assessing the Effects of Strength Exercise on Insulin Sensitivity in Obese Individuals  

To begin, instruct the participant to execute three sets of eight repetitions in each of the seven exercises, categorized as easy on the Omni RES scale. For the second familiarization session, guide the participant to perform three sets of eight repetitions in each of the seven exercises considered hard or between levels five and seven. During the third familiarization session, guide the participant to perform challenging exercises rated between level seven and nine.In the familiarization session four, instruct the participant to carry the exercises ranging from hard to extremely hard, or between levels nine and 10. After the last familiarization session, commence the strength tests in each of the seven exercises for a total of 72 hours. Print random sequences corresponding to the numbers one, for high volume, two for low volume and three for control.Place each of these sequences into sequentially numbered opaque envelopes and seal these envelopes. After the strength tests, open these sealed envelopes to reveal the session order. Instruct the participant to perform three sets of the seven exercises aiming for maximum repetitions with the weight determined by the eight RM test.Then provide the participant with a post-session meal between nine and 9:30 PM.Advise the participant to refrain from consuming other food until the OGTT the following morning. Finally, permit the participant to leave. In session two, ask the participants to perform low-volume exercises and provide them with the post-session meal as demonstrated earlier.In session three, position the participant in each exercise equipment, but advise against any muscle contraction maintaining this for 30 seconds. Provide the post-session meal as shown earlier. After collecting the fasting blood sample early morning, ask the participants to ingest 75 grams of glucose in a 300 milliliter solution.Then collect blood samples to measure plasma glucose in serum insulin concentration. Input the oral glucose tolerance test data, or OGTT into separate spreadsheets with the help of an unbiased research collaborator. Calculate the area under the curve for glucose and insulin following the trapezoidal rule.Proceed with the computation of the oral glucose insulin sensitivity index. Calculate the matsuda insulin sensitivity index and determine the Cedarholm's index. Next, calculate the muscle insulin sensitivity index.Determine the gut index. Proceed with the computation of the Avignon index. Then determine the Stumvoll index.Glycemia and insulin responses to OGTT after no exercise, 21 strength exercises and seven strength exercise protocols in obese adults are presented. The glucose and insulin peaks were seen at the 30-minute mark, followed by a steady decline until the 120-minute measurement. The insulin sensitivity indexes indicate that individuals with lower glycemia and insulin concentrations after a standard glucose challenge have better insulin sensitivity.

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89 visualizações.  Federal University of the Jequitinhonha and Mucuri Valleys. Para começar, instrua o participante a executar três séries de oito repetições em cada um dos sete exercícios, categorizados como fáceis na escala Omni RES. Para a segunda sessão de familiarização, orientar o participante a realizar três séries de oito repetições em cada um dos sete exercícios considerados duros ou entre os níveis cinco e sete. Durante a terceira sessão de familiarização, orientar o participante a realizar exercícios desafiadores classificados entre os ní...