Strength Training, Cardio, And Insulin Sensitivity: Two Pathways, One Protocol
Insulin sensitivity is the master metabolic variable for most adults over 35. When it’s high, the body handles food well, body composition stays favorable, and metabolic disease risk is low. When it’s blunted — meaning the same dose of insulin produces less of a glucose-clearing response — every downstream metabolic system is affected. Weight rises. Energy drops. Inflammation climbs. The skeletal muscle stops taking up glucose efficiently. The liver starts overproducing it.
The single most reliable way to improve insulin sensitivity in adults is exercise. And the most interesting finding of the last decade is that the two training modalities — strength and cardio — produce the improvement through different molecular pathways, and the combination compounds.
The molecular case
In the 2023 paper I co-authored with Munoz and colleagues (Cellular and Molecular Life Sciences, PMID: 37052684), we used a mouse model of impaired glucose handling — mice with reduced GLUT4 expression — and compared short-term endurance and resistance training head-to-head.
Both training modalities improved insulin signaling in skeletal muscle. But they did it through different intracellular routes.
Endurance training upregulated AMPK and PGC-1α — the master regulators of mitochondrial biogenesis. The muscle became more oxidatively efficient.
Resistance training upregulated Akt and downstream insulin signaling proteins. The muscle became more insulin-responsive at the receptor level.
When both were combined, the effect on insulin sensitivity was greater than either alone, and importantly, the molecular signature was complementary — meaning the two training modes were not redundant.
Figure reference: Muñoz VR, Botezelli JD et al., “Effects of short-term endurance and strength exercise in the molecular regulation of skeletal muscle in hyperinsulinemic and hyperglycemic Slc2a4+/− mice.” Cell Mol Life Sci. 2023;80(5):122. PMID: 37052684. Reference Figure 3: Western blots of AMPK vs Akt phosphorylation across training groups.
Why this matters in human terms
The clinical translation of these findings has been arriving. A 2017 randomized trial (Jelleyman et al., Obesity Reviews) compared high-intensity interval training to moderate-intensity continuous training in adults with type 2 diabetes. Both improved HbA1c. The HIIT effect was larger per minute of training time, but the moderate-intensity group had higher adherence.
A 2018 trial (Stensvold et al., Obesity) compared combined endurance + resistance training to either alone in middle-aged metabolic-syndrome patients. The combination produced the largest reduction in fasting insulin and the largest improvement in HOMA-IR. The single-modality groups improved, but less.
The pattern in the data is clear: anyone with insulin resistance or pre-diabetes should be running both modalities, not just one.
The dose
For insulin sensitivity specifically, the dose-response evidence suggests: two to three strength sessions per week, full-body, progressive loading; three to four cardio sessions per week, including at least one higher-intensity interval session; total weekly training time of 4–5 hours.
This is also what twelve weeks of the BTZ Elite protocol delivers. Bioimpedance and fasting insulin are tracked at baseline, week 6, and week 12. Most clients see HOMA-IR drop by 25–40% over that window.
This article is educational and is not medical advice. Diego Botezelli is a researcher and coach, not a physician — he does not diagnose, treat, or prescribe. Talk to your doctor before changing medication, supplements, or training, especially if you have a health condition or take prescription drugs.
Want this applied to your own physiology?
The same evidence standard behind this article runs through every program I write, in person in Port Coquitlam or online.
