REF-1556 · Popov et al., 2015 · Fiziologiia Cheloveka · Paper · PubMed

Does riding past 60 min add signal?

In nine trained men at 60% of VO2max, PGC-1α was comparable at 60 and 90 min, and VEGFA rose only at 90 min. One session each, gene markers, abstract only, no adaptation or performance.

Main caveat: Abstract only, in English, of a paper published in Russian with an English translation. No copy in PubMed Central or Europe PMC.
thin evidenceMeasured on trained to highly trained athletes

Nine athletes with a VO2max of 59 mL/min/kg cycled at 60% of VO2max for 30, 60 and 90 min. The study looked at the kinases that regulate PGC-1α, at the expression of regulatory genes for mitochondrial biogenesis, and at genes for muscle breakdown. PGC-1α gene expression rose with exercise though AMPK, p38 MAPK and CaMKII showed no activation.

The rise was comparable at 60 and at 90 min. VEGFA expression increased only after 90 min. Even 90 min did not activate the FOXO1 to E3 ubiquitin ligase pathway or raise catabolic gene expression.

Our reading: one signal plateaued between 60 and 90 min and one gene appeared only at the longest duration; nine athletes cannot support either as a rule, and neither is an adaptation.

Protocol

Who: nine athletes; men by the title. No age, sport or training history in the abstract.
Sessions: 30, 60 and 90 min of cycling at 60% of VO2max. That the same nine did all three is the plain reading of the abstract; order and days between are not given.
Measures: signalling kinases that regulate PGC-1α (AMPK, p38 MAPK, CaMKII), expression of mitochondrial-biogenesis regulators, VEGFA, the FOXO1 to E3 ubiquitin ligase pathway and catabolic genes. Biopsy timing and fuel state are not in the abstract.
Funding and interests: PubMed flags non-US government support; funders and conflict statements are not in the abstract.

Key Results

Measure30 min60 min90 min
PGC-1α gene expressionno comparison printedincreasecomparable to 60 min
VEGFA gene expressionno rise reportedno rise reportedincreased
AMPK, p38 MAPK, CaMKII activationnone reported, though PGC-1α rose
FOXO1-E3 ubiquitin ligase pathway, catabolic genesno activation, no increase, even at 90 min
No values at all. The abstract prints no fold-changes, p values or times of biopsy.
Comparable, not the same. No equivalence test appears, and n = 9.
The 30-min PGC-1α result is not separately described in the abstract.

Mechanisms

Measured: the pattern above.
Authors' interpretation: the abstract says adaptation depends on session intensity and duration, and describes a PGC-1α rise occurring without activation of the kinases named. Which time points those kinases were read at is not stated, so a transient activation between samples cannot be ruled out (inference).
Not reported in the abstract: mitochondrial content or function, capillary growth, performance, repeated sessions. VEGFA expression is a candidate for capillary signalling, not capillary growth (inference).

Practical Application

Does riding past 60 min add signal? In nine trained men at 60% of VO2max, PGC-1α was comparable at 60 and 90 min, and VEGFA rose only at 90 min. One session each, gene markers, abstract only, no adaptation or performance.
Good for: an honest note that the molecular case for longer sessions at this intensity is thin; in trained humans, this is one small study, and it points both ways.
Not good for: telling an athlete sessions past 60 min are wasted. VEGFA, durability, fat use and training volume are other things a long session may do (inference), and none of those outcomes was tested here.
Not good for: telling an athlete long sessions are needed for signalling. One gene at one time point in nine people is not that.
Not good for: the double. Splitting a session was not tested.
Not from this paper: the base's guides on long sessions and aerobic base rest on other evidence; do not cite this as support for a set duration.

Limitations

Abstract only, in English, of a paper published in Russian with an English translation. No copy in PubMed Central or Europe PMC.
No numbers, and no statistics, in what was read.
n = 9, with no control session described in the abstract.
A marker, not an outcome. Gene expression after one session has no shown link to what these athletes would gain over a block.
Fixed relative intensity only. Whether this holds at a lower or higher intensity, or in less-trained people, is unknown here.
Fuelling and glycogen are not given in the abstract, though they affect the same pathways.
How this entry was checked and changed
Why this level

(from the abstract) — mechanistic laboratory study with no performance outcome, in the rubric's words. No copy in PubMed Central or Europe PMC; only the English abstract in PubMed was read, and it prints no fold-changes or statistics