Increasing mitochondria improves performance

How and why increasing your mitochondria levels could be the key to improving your triathlon performance

Credit: wir0man/Getty

Many triathletes fall into the trap of training at one pace. They’re of the mentality that if they don’t work up a sweat, the session’s redundant. This is a surefire way for your performance to plateau. Broadly speaking, you should spend around 80-90% of your training at pretty easy intensity with the remainder hard. And when we say hard, we mean lungs-bursting and sweat-pouring hard. This so-called ideal has recently been supported in the labs by leading sports scientists Carsten Lundby and Robert Jacobs.


“Our research has identified the most powerful individual physiological marker predictive of endurance performance is skeletal muscle oxidative capacity,” explains Jacobs. “This comes down to the mitochondria in your cells. Our lab also observed the greatest alterations in mitochondrial function and improvement occurs in response to high-intensity interval training.”

Mitochondria are your power plants. They’re found in most cells, including muscles, and generate the energy for cells to perform their multiple roles, primarily through glucose and fat metabolism. What Jacobs and Lundby have highlighted is just how important they are to speed, stamina and power, primarily by showing how mitochondria grow [more on how mitochondria grow in the Mitochondria Biogenesis illustration below].

Jacobs and Lundby showed that mitochondria adapt to very specific training. For instance, the researchers illustrated that when healthy volunteers undertook six weeks of endurance training, volume of mitochondria expanded by 46% to increase fat oxidation. Conversely, intense exercise – for instance, repeated 60sec efforts of high-intensity swimming, cycling or running at a workload corresponding to peak power – induces what’s termed ‘global improvements in respiratory capacity’. This includes well-known physiological terms like lactate threshold.

“Our data highlights the importance of altering the intensity and/or duration within an exercise training programme, particularly when training for endurance events,” says Jacobs. “Basically, it maximises skeletal muscle mitochondrial function and increases exercise performance.”

This research could change the whole lexicon of training. No longer will you train your VO2max – you’ll look to increase mitochondrial volume. Increase speed? Not any more. It’ll all be about improving skeletal respiratory capacity. This might sound flippant but this focus on mitochondria and triathlon performance does have potential benefits….


Protein strengthens mitochondria, helping growth and so increasing power production, so ensure you eat sufficient protein post-exercise. As a general rule, have 1.2g/kg per day if exercising 1-1.5hrs; 1.4g/kg/day for 2-4hrs; and 1.7g/kg/day for more than 4hrs.

Training with low glycogen levels – like before breakfast – activates significant numbers of signalling proteins that promote an endurance phenotype; in other words, your mitochondria will increase in volume to burn more fat.

Studies have shown ingestion of vitamin C post-exercise decreases mitochondria biogenesis (growth) and hampers training-induced adaptation, so stay off the oranges post-session.



Jacobs and Larsen showed that mitochondrial volume initially increases through swelling. If regular exercise continues, and at varying intensities, mitochondrial volume increases via ‘length expansion’. This’ll result in greater energy production at different intensities of tri, meaning you race faster.