Metabolic Stress for Muscle & Brain Hypertrophy
One mechanism for building muscle is metabolic stress. In bodybuilding, that usually means using constant tension and going for the "pump and burn" effect.
Metabolic stress results from exercise that's reliant on anaerobic glycolysis for ATP production. This type of training results in a buildup of metabolites like lactate and hydrogen ions which have been linked to anabolic effects. It's typically targeted by increasing exercise volume and reducing rest intervals between sets.
While this type of training has commonly been associated with just building muscle, emerging research suggests it could be beneficial for building our brains as well.
The Geeky Stuff
Brain-derived neurotrophic factor (BDNF) has been shown to increase in an intensity dependent manner in response to aerobic exercise in various studies. HIIT (high intensity interval training) has been shown to evoke especially large serum BDNF levels in response to training.
BDNF is a protein that plays a variety of important roles for optimal brain function, including promoting the survival of nerve cells by playing a role in growth, differentiation, and maintenance of nerve cells. BDNF is also involved in signal transduction which is important for cell to cell communication.
Most interestingly, decreased levels of this protein is commonly found in patients with cognitive diseases like Alzheimer's and Parkinson's. Researchers wanted to examine if resistance training could also play a role in influencing the levels of BDNF in the human body.
A crossover study on 11 males and 5 females was conducted. The groups were recruited to either do strength-based resistance training (5x5 based off of their 5 RM with 180 seconds of recovery) and hypertrophy-resistance training (3x10 based off their 10 RM with 60 seconds of recovery). Researchers wanted to examine the effects on serum BDNF and blood lactate levels immediately post-exercise and then 30 minutes later.
Blood samples were drawn after warm-ups, immediately after exercise, and 30 minutes post-exercise. The results showed that there was a significantly greater increase in BDNF post-exercise following hypertrophy training and there was a positive relationship between levels of lactate and BDNF.
These findings were consistent with previous research showing factors like blood lactate levels and exercise intensity are positively correlated with increased levels of BDNF.
Researchers postulated that the lower recovery times during the hypertrophy training sessions resulted in greater exposure to high blood flow and increased release of BDNF compared to the strength training workouts where the longer rest between sets allowed for a return to rested state blood flow levels.
The Take Home Message
Lifters should include lactate-inducing workouts into their routines for some additional neuroprotection and muscle. This can be done by doing bodybuilding-style workouts that can create high levels of metabolic stress like drop sets, Gironda's 8 x 8, or a shortened version of German Volume Training.
- Potential mechanisms for a role of metabolic stress in hypertrophic adaptations to resistance training.
- Marquez, C. M., Vanaudenaerde, B., Troosters, T., & Wenderoth, N. (2015). High-intensity interval training evokes larger serum BDNF levels compared with intense continuous exercise. Journal of Applied Physiology, 119(12), 1363-1373. doi:10.1152/japplphysiol.00126.2015
- Marston, K. J., Newton, M. J., Brown, B. M., Rainey-Smith, S. R., Bird, S., Martins, R. N., & Peiffer, J. J. (2017). Intense resistance exercise increases peripheral brain-derived neurotrophic factor. Journal of Science and Medicine in Sport. doi:10.1016/j.jsams.2017.03.015