New research from Japan has demonstrated the role of hypoxia in muscle growth, and shown that exposing muscle cells to low oxygen conditions can increase muscle growth compared to normoxia.
Hypoxia Is Important For Muscle Growth
Researchers have long shown that one of the important stimuli for muscle growth is local hypoxia. That is, a reduced amount of oxygen in the muscle itself is one of the factors which stimulates muscle growth. For example during knee extension exercise, there is less oxygen in the distal end of the thigh muscles (by the knee) than the proximal end (nearer the hip), and sure enough muscle growth is greatest at the distal region. These researchers sought to understand why this is the case, and whether simply exposing muscle cells to reduced oxygen environments could stimulate muscle growth.
What Did They Do?
They isolated muscle cells and grew them in normoxia (20.9% oxygen), or in hypoxia of 15%, 10%, or 5% oxygen, for 6 days. The results demonstrated that compared to normoxic conditions, moderate hypoxia (10% & 15% oxygen) activated the expression of specific genes related to muscle size, and increased muscle size across the course of the 6 days.
What Does This Mean In Practice?
It can be hard to translate studies done in the lab to the real world, however this provides yet more support for the idea that undertaking resistance training in hypoxic conditions can lead to greater improvements in muscle size and strength than completing the same session in normoxia. In practice, exposure to simulated altitude during resistance training has already been shown to increase muscle hypertrophy even when training at only 20% 1 rep max, and this new research adds further understanding as to why this might be. It also shows that we should aiming to train in moderate hypoxia for the best results, so training at 15% oxygen, or 2700m might be just right for optimising the response- exactly the altitude our chamber is set at!
If you’re not yet convinced of the benefits of strength training for endurance athletes, check out our blog on exactly that topic, and if you need any pointers on where to get started with your altitude training, get in touch below!
Reference: Sakushima, K., Yoshikawa, M., Osaki, T., Miyamoto, N., & Hashimoto, T. (2020). Moderate hypoxia promotes skeletal muscle cell growth and hypertrophy in C2C12 cells. Biochemical and Biophysical Research Communications.