Something You Do Not Know About Muscles

Picture from Burke et al, 2024

This is a very interesting finding about muscles. The muscles we use while exercising can actually communicate with our adipose (fat) stores in our body.

This study was done with 32 human subjects. A single bout of resistance exercise (or strength training) releases muscle specific microRNA-1 (miR-1) from muscles that are then transported to abdominal fat tissue via extracellular vesicles or EVs to stimulate lipolysis. Lipolysis is the breakdown of fats and other lipids to release fatty acids. This means you can use fats for energy, sparing your carbohydrate and protein.

I know what some of you reading must be thinking. Is spot reduction possible? Spot reduction means selective loss of body fat in regions involved in the exercise. Meaning can we isolate the fat in the abdomen (for men) by doing cruches or sit-ups?  Or doing lunges for the buttock and thighs (for women) and get rid of the fat there first? 

Well, sorry to disappoint you. In this study, the exercises were mainly done in the lower body- squats, leg press, leg extension and also lat pulldown (for the upper body). 3 sets of 8 reps at 80 percent of 1 rep max on the aboved mentioned exercises were performed. A fourth set to failure was performed straight after.

The lipolysis or fat breakdown in the adipose tissue was in a non specific area - the abdominal region. This was confirmed by the EV's found there.

Perhaps this is an interesting consideration suggesting that our muscles can function like a secretory organ. Like a giant endocrine organ in the body, more than we realize anyway. (Note : thoughts are my own, not from the study).

We are definitely only scratching the surface of understanding how exercise has so many other unknown benefits.

The women in the study did not have as strong an effect compared to the men in the study. Also note that is is a relatively small study with only 32 subjects.

If you are not already doing any strength training, you should. Not only it can increase your bone density, helps with insulin sensitivity, promote better sleep etc, it can also break down your stored fat.

Reference

Burke BI, Ismaeel A, Long DE et al (2024). Extracellular Vesicle Transfer Of miR-1 To Adipose Tissue Modifys Lipolythic Pathways Following Resistance Exercise. JCI Insight. DOI: 10.1172/jci.insight.182589