The Claim

In previously untrained to moderately trained adults, endurance training (ET), high-intensity interval training (HIT), and sprint interval training (SIT) are associated with similar percentage increases in skeletal muscle mitochondrial content, averaging 23–27%, after adjusting for training frequency, duration, and initial fitness level, with no significant differences between the training modalities, indicating that all three forms of exercise effectively stimulate mitochondrial biogenesis.

Source: Effects of Exercise Training on Mitochondrial and Capillary Growth in Human Skeletal Muscle: A Systematic Review and Meta-Regression

What the research says

Supports is higher

Support is ahead, but a single strong opposing study can change this.

Supports
52score
Challenges
0score

These are independent scores, not a percentage. Higher-grade studies count more, so a single strong opposing study can outweigh several weaker ones.

Quantitative
1 study reviewed
In plain English

For people who aren't super fit to start with, different types of workouts—like steady cardio, intense interval training, and short sprints—boost the energy powerhouses in their muscles by about the same amount, around 23–27%.

See the scientific wording

In previously untrained to moderately trained adults, endurance training (ET), high-intensity interval training (HIT), and sprint interval training (SIT) are associated with similar percentage increases in skeletal muscle mitochondrial content, averaging 23–27% after adjusting for training frequency, duration, and initial fitness level, with no significant differences between training modalities, indicating that all three forms of exercise effectively stimulate mitochondrial biogenesis.

What the research says

1 study
  1. Study: Effects of Exercise Training on Mitochondrial and Capillary Growth in Human Skeletal Muscle: A Systematic Review and Meta-Regression

    The study found that different types of exercise—like steady jogging, intense intervals, and all-out sprints—boost muscle energy factories (mitochondria) by about the same amount when done regularly, which supports the claim.

Score breakdown, mechanism chain, raw evidence, ideal studies needed & 1 supporting studies

Fit Body Science verdict — we translate health claims into clear verdicts backed by peer-reviewed research.

Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.