The best exercise to increase mitochondria is aerobic training, done regularly, with some high-intensity intervals mixed in. Human studies with muscle biopsies show that endurance training and high-intensity interval training (HIIT) both increase mitochondria in muscle. How much you train mainly drives how many mitochondria you build, while how hard you train mainly drives how well they work, so a mix of steady sessions and intervals covers both.
Key Takeaways
- Endurance training and HIIT are the best-studied ways to increase mitochondrial content and function in human muscle.
- A 2018 review found training volume is a key driver of mitochondrial content, while exercise intensity is a key driver of mitochondrial respiratory function.
- In a 12-week trial, HIIT raised maximal mitochondrial respiration by 49% in young adults and 69% in adults aged 65-80; resistance training alone did not significantly change it.
- Measurable changes in muscle can appear within two weeks of interval training, but gains faded within two weeks when training volume dropped sharply.
- Strength training still matters: it built lean mass in the same trial, and U.S. guidelines advise it at least 2 days a week alongside 150-300 minutes of moderate aerobic activity.
Evidence grade: Moderate. Consistent findings from many human training studies that measured mitochondria in muscle biopsies, plus review articles; most studies are small (7-30 people), short (2-12 weeks) and done mainly in young men.
Why Mitochondria Matter for Energy
Mitochondria are structures inside cells that convert the energy from food into a form cells can use. Through a process called oxidative phosphorylation, they use oxygen to produce adenosine triphosphate (ATP), the cell's main energy source. Each cell contains hundreds to thousands of them. Muscle needs a lot of ATP during sustained activity, which is why exercise scientists study how training changes muscle mitochondria. For a broader overview, see our guide to mitochondrial health.
Researchers look at two different things. Mitochondrial content is how much mitochondrial material your muscle has, often measured by the activity of an enzyme called citrate synthase. Mitochondrial respiratory function is how much oxygen the mitochondria can use to make energy. Building new mitochondria is called mitochondrial biogenesis. A 2018 review by Granata and colleagues found that these two measures do not always rise together: training volume appears to be a critical factor for content, while relative exercise intensity is an important factor for respiratory function.
Exercise Types Compared
| Exercise type | Example used in studies | What human studies found for mitochondria |
|---|---|---|
| Endurance (moderate, continuous) | Steady cycling, running or brisk walking | Increases mitochondrial content; content changes track training volume. In one trial, combined endurance plus strength training raised respiration 38% in young adults but not significantly in older adults. |
| High-intensity interval training (HIIT) | 4 x 4 minutes hard cycling with 3-minute easy recovery, 3 days a week | Raised maximal mitochondrial respiration 49% (young) and 69% (older adults) over 12 weeks; beat continuous training matched for total work in a 2-week single-leg study. |
| Low-volume HIIT | 8-12 x 60 seconds hard with 75 seconds easy, 3 times a week | Increased mitochondrial enzymes and proteins after just 6 sessions over 2 weeks. |
| Sprint interval training (SIT) | 4-10 x 30-second all-out sprints | Increases mitochondrial content about as much as continuous training despite far less total exercise time; in one 4-week study, only SIT significantly raised respiration (25%). |
| Resistance training | 4 sets of 8-12 reps, upper and lower body, 2 days a week each | Did not significantly increase mitochondrial respiration in a 12-week trial, but increased lean mass. |
Endurance Training: Volume Builds Content
Steady aerobic exercise is the classic stimulus for mitochondrial growth. Reviews of human studies agree that endurance training can increase mitochondrial content and function, and that the total amount of training is a key driver of how much new mitochondrial material muscle builds.
A study by Granata and colleagues shows how strongly volume matters. Ten healthy men did interval cycling in three phases. Four weeks of normal training three times a week did not change any mitochondrial measure. A 20-day block of twice-daily training then raised mitochondrial respiration and citrate synthase activity by about 40-50%. When training dropped to five sessions over two weeks, most of those gains were no longer significant. Consistency over months, not a short burst, is what keeps the adaptations.
HIIT: Intensity Improves Function
High-intensity interval training alternates hard efforts with easy recovery. It has the strongest head-to-head data for improving how well mitochondria work.
- Robinson 2017 (Mayo Clinic): adults aged 18-30 and 65-80 who did not exercise regularly were randomized to 12 weeks of HIIT, resistance training or combined training. The HIIT program was three days a week of cycling intervals (4 x 4 minutes at over 90% of peak oxygen uptake, with 3 minutes of easy pedaling) plus two days of 45-minute treadmill walks. HIIT increased maximal mitochondrial respiration by 49% in the young group and 69% in the older group, and increased mitochondrial protein synthesis.
- MacInnis 2017: ten young active men trained one leg with intervals and the other leg with continuous cycling, matched for total work, for six sessions over two weeks. The interval leg showed greater increases in citrate synthase activity and mitochondrial respiration.
- Little 2010: seven men did 8-12 one-minute hard intervals with 75 seconds of recovery, six sessions over two weeks. Mitochondrial enzymes and proteins in the thigh muscle increased, and cycling time-trial performance improved.
Sprint interval training, with very short all-out efforts, is the most intense version. A review by MacInnis and Gibala concluded that it increases mitochondrial content to a similar extent as moderate continuous training despite much less total exercise time. In a separate four-week study of 29 men, maximal mitochondrial respiration increased significantly only in the sprint group (by 25%), while markers of mitochondrial content did not change in any group.
Where Strength Training Fits
Lifting weights is not the main way to build mitochondria. In the Robinson trial, 12 weeks of resistance training did not significantly increase mitochondrial respiration in either age group. It did increase lean mass, and every program in that trial improved insulin sensitivity. U.S. physical activity guidelines recommend muscle-strengthening activity at least two days a week for adults, so strength work belongs in the plan for reasons other than mitochondria.
A Practical Weekly Plan
The research points to a simple approach: build a base of regular aerobic activity, add one to three interval sessions, and keep two strength days. The Physical Activity Guidelines for Americans advise at least 150-300 minutes a week of moderate aerobic activity, such as brisk walking, plus muscle strengthening on at least two days. A week modeled on the studies above might look like this:
- 2-3 days: 30-45 minutes of steady aerobic exercise (brisk walking, cycling, swimming or jogging) to build volume.
- 1-2 days: intervals, for example 4 x 4 minutes hard with 3 minutes easy between, after a warm-up.
- 2 days: strength training for the major muscle groups.
- Every day: move more and sit less.
Start below these levels if you are new to exercise and build up over several weeks. The heart is especially rich in mitochondria; our article on why the heart has more mitochondria explains why.
Safety and Interactions
- Build up gradually. HIIT and sprint intervals are hard efforts. Most of the studies above enrolled healthy volunteers, and the Robinson trial excluded people with heart or metabolic conditions, so the results may not apply to everyone.
- Talk to your clinician first if you have a heart condition, chest pain, dizziness or shortness of breath with activity, are pregnant, or have not exercised in a long time, before starting high-intensity intervals.
- Medications: if you take medicines that affect heart rate, blood pressure or blood sugar, ask your doctor or pharmacist how intense exercise fits with them.
- Supplements are not a substitute for training. The mitochondrial changes described here come from exercise itself.
Frequently Asked Questions
What is the best exercise to increase mitochondria?
Aerobic training done consistently, with some high-intensity intervals. Endurance volume mainly builds mitochondrial content, and intervals mainly improve how well mitochondria use oxygen. In a 12-week trial, HIIT raised mitochondrial respiration by 49% in young adults and 69% in older adults.
How long does it take to increase mitochondria?
Studies have measured increases in mitochondrial enzymes and proteins after as few as six interval sessions over two weeks. Larger, lasting changes come from months of regular training.
Does lifting weights increase mitochondria?
Not much on its own. In a 12-week trial, resistance training did not significantly increase mitochondrial respiration, though it built lean mass. Combine it with aerobic work.
Do mitochondrial gains go away if I stop training?
They can fade quickly. In one study, gains from three weeks of very high-volume training were mostly gone after two weeks of much lighter training. Regular exercise maintains them.
Does walking increase mitochondria?
Moderate continuous exercise such as brisk walking is part of endurance training, and total training volume appears to be a key driver of mitochondrial content. Adding some faster intervals adds an intensity stimulus that steady walking alone may not provide.
Sources
- Granata C, Jamnick NA, Bishop DJ. Training-Induced Changes in Mitochondrial Content and Respiratory Function in Human Skeletal Muscle. Sports Med. 2018.
- Robinson MM, Dasari S, Konopka AR, et al. Enhanced Protein Translation Underlies Improved Metabolic and Physical Adaptations to Different Exercise Training Modes in Young and Old Humans. Cell Metab. 2017.
- MacInnis MJ, Gibala MJ. Physiological adaptations to interval training and the role of exercise intensity. J Physiol. 2017.
- MacInnis MJ, Zacharewicz E, Martin BJ, et al. Superior mitochondrial adaptations in human skeletal muscle after interval compared to continuous single-leg cycling matched for total work. J Physiol. 2017.
- Little JP, Safdar A, Wilkin GP, Tarnopolsky MA, Gibala MJ. A practical model of low-volume high-intensity interval training induces mitochondrial biogenesis in human skeletal muscle: potential mechanisms. J Physiol. 2010.
- Granata C, Oliveira RS, Little JP, Renner K, Bishop DJ. Training intensity modulates changes in PGC-1α and p53 protein content and mitochondrial respiration, but not markers of mitochondrial content in human skeletal muscle. FASEB J. 2016.
- Granata C, Oliveira RS, Little JP, Renner K, Bishop DJ. Mitochondrial adaptations to high-volume exercise training are rapidly reversed after a reduction in training volume in human skeletal muscle. FASEB J. 2016.
- MedlinePlus Genetics, National Library of Medicine. Mitochondrial DNA.
- U.S. Department of Health and Human Services, ODPHP. Top 10 Things to Know About the Second Edition of the Physical Activity Guidelines for Americans.
Disclosure: OPA Nutrition sells supplements, including products mentioned in this article. This content is for education only and is not medical advice. Statements about dietary supplements have not been evaluated by the Food and Drug Administration. These products are not intended to diagnose, treat, cure, or prevent any disease. Talk to your healthcare provider before using any supplement, especially if you take medication or have a medical condition.
Written and reviewed by Michael Gonzales, Founder, OPA Nutrition · Last reviewed: · How OPA researches and writes
