Prior research (2) has uncovered the therapeutic effects physical training can provide individuals suffering from type II diabetes. Additionally, training protocols (3) have also focused on the appropriate exercise dosage to successfully increase insulin activity in skeletal muscles. However, many sedentary type II diabetic adults still suffer from exercise anxiety with the very thought of entering a gym, or exercising alongside a YouTube fitness influencer. Therefore, the goal for any fitness professional should be to reiterate to a sedentary type II diabetic that the appropriate training dosage is not as daunting as they once thought. Further, the potential benefits elicited through training should serve as a tool to alleviate most of their exercise anxiety. Thus, that is the reason why this blog will serve as that tool to uncover the effects that a low intensity resistance training modality (2) has in inducing an increase in insulin activity.
Resistance Training
In Holten and colleagues (2004) study the researchers tested ten older type II diabetic, and matched them against six healthy participants. The participants were matched with respect to age (59 to 64 years) and weight (75 to 90kgs). The testing protocol consisted of 6 weeks, low-intensity, single-leg strength training protocol for both groups. Participants trained 3 times per week for 30 minutes each session. During the first two weeks participants completed 3 sets of 10 repetition at 50% intensity. The proceeding weeks consisted of 4 sets of 8 to 12 repetitions at 70–80% intensity. The exercises used were leg press, leg curl, and leg extension.
The results revealed that the leg glucose clearance rates in both legs decreased in type II diabetics. Among diabetics, the resistance-trained leg experienced an increase in blood flow. This was followed by a decrease of glucose extraction in type II diabetics. Muscle glycogen content for type II diabetics was similar to the healthy participants. Slightly better hypertrophy was observed in the trained type II fibers of the diabetics. GLUT4 density in the trained leg of the diabetics experienced a 40% increase. For type II diabetics, their insulin receptors increased by 6%, PKB- / (Akt 1/2) increased by 7%, GS protein content increased by 5%, and GS total activity increased by 4%. The results demonstrated that low intensity resistance training is capable of stimulating insulin activity for type II diabetics. This phenomenon occurred despite there not being a significant increase in skeletal muscle hypertrophy.
Endurance Training
To substantiate these findings, a previous single-leg endurance training protocol conducted by Dela et al. (1995), studied whether a 10 weeks, 6 days per week, endurance training protocol using a bicycle ergometer could induce increases in insulin action. This particular low-to-moderate intensity training protocol was established at 70% intensity. The participants' ages ranged between 59 to 64 years. In spite of their age, the type II diabetics were shown to have normal glucose clearance following chronic exercise. Contrarily, the same glucose clearance was not observed in a single bout of exercise in type II diabetics (1). Thus, illustrating the importance of committing to a consistent, and safe exercise routine.
As previously highlighted, both studies managed to demonstrate that insulin activity can increase in response to a low-intensity resistance training program. These adaptations would occur independent of a significant increase in muscle hypertrophy. The implications suggest that both endurance training and low-intensity resistance training induces an increase in protein signaling and insulin activity. Moreover, older, sedentary type II adults will be able to safely commit to these forms of exercising.
References
1. Dela, F., Larsen, J. J., Mikines, K. J., Ploug, T., Petersen, L. N., & Galbo, H. (1995).
Insulin-stimulated muscle glucose clearance in patients with NIDDM. Effects of one-legged physical training. Diabetes, 44(9), 1010–1020. https://doi.org/10.2337/diab.44.9.1010
2. Holten, M. K., Zacho, M., Gaster, M., Juel, C., Wojtaszewski, J. F., & Dela, F. (2004).
Strength training increases insulin-mediated glucose uptake, GLUT4 content, and insulin signaling in skeletal muscle in patients with type 2 diabetes. Diabetes, 53(2), 294–305. https://doi.org/10.2337/diabetes.53.2.294
3. Ligtenberg, P. C., Hoekstra, J. B., Bol, E., Zonderland, M. L., & Erkelens, D. W. (1997).
Effects of physical training on metabolic control in elderly type 2 diabetes mellitus patients. Clinical science (London, England : 1979), 93(2), 127–135. https://doi.org/10.1042/cs0930127