Sprint-interval but not continuous exercise increases PGC-1α protein content and p53 phosphorylation in nuclear fractions of human skeletal muscle.
Level 3 - non-randomized controlled study
Controlled comparative trial in human participants without explicit mention of randomization in the abstract
PubMed 28281651 · doi:10.1038/srep44227
What was done
Nineteen men performed either 24 minutes of moderate-intensity continuous cycling at 63% of peak power (CE) or a sprint-interval exercise protocol (SIE) consisting of four 30-second "all-out" cycling sprints. Muscle biopsies from the vastus lateralis were obtained pre-exercise, immediately post-exercise (+0 h), and 3 hours post-exercise (+3 h) to evaluate key mitochondrial biogenesis regulatory proteins in nuclear fractions.
What was found
The abstract reports directional changes without quantitative values, confidence intervals, or p-values. Nuclear p53 and PHF20 protein levels increased at +0 h across both exercise protocols with no difference between groups. Nuclear p53 phosphorylation and nuclear PGC-1α protein content increased immediately (+0 h) following sprint-interval exercise, but not after continuous exercise.
Why it matters
These findings suggest that brief sprint-interval exercise may be more potent than continuous moderate exercise at rapidly activating early nuclear regulatory pathways linked to mitochondrial biogenesis.
Limits
The study evaluated a small sample of 19 men only, limiting generalizability to women and clinical populations. The abstract does not specify whether participants were randomized, lacks numerical data, and measures only acute signaling markers rather than long-term mitochondrial adaptations or functional performance gains.
Cited by
- supports Both high-intensity interval training and Zone 2 moderate-intensity training increase mitochondrial biogenesis in skeletal muscle, with HIIT stimulating it more rapidly.