REF-1074 · Ahlquist et al., 1992 · European Journal of Applied Physiology and Occupational Physiology, · Paper · PubMed
The effect of pedaling frequency on glycogen depletion rates in type I and type II quadriceps muscle fibers during submaximal cycling exercise
8 men, 30 min at about 85% of aerobic capacity at 50 vs 100 rev/min: type II fibres lost more glycogen at 50 rev/min (49% vs 33%), type I fibres did not differ (46% vs 35%); one acute session, no training or performance outcome
The study asked whether pedalling frequency, at a constant metabolic cost, changes the pattern of glycogen depletion by fibre type. Content from the abstract only; the database record marks the abstract as truncated, so any sentence after the conclusion quoted below is not available.
Participants
n=8 men (abstract: "eight men"). Age and training status are not given in the abstract.
Protocol
On 2 separate days, 30 min of cycling at approximately 85% of individual aerobic capacity, at pedalling frequencies of either 50 or 100 rev.min-1 (constant metabolic cost between conditions).
Vastus lateralis biopsies immediately before and after exercise.
Fibres classified as type I (slow twitch) or type II (fast twitch) with a myosin ATPase stain; glycogen content quantified by microphotometry of periodic acid-Schiff stain (mean optical density, D).
Key Results
| Fibre type | 50 rev.min-1 | 100 rev.min-1 | Comparison |
|---|---|---|---|
| Type I | 46% decrease, 0.52 (0.07) to 0.28 (0.04) D units | 35% decrease, 0.48 (0.04) to 0.31 (0.05) D units | not different (P > 0.05) |
| Type II | 49% decrease, 0.53 (0.06) to 0.27 (0.04) units | 33% decrease, 0.48 (0.04) to 0.32 (0.06) units | greater at 50 rev.min-1 (P < 0.05) |
Values are mean (SEM).
Authors' conclusion: cycling at the same metabolic cost at 50 rather than 100 rev.min-1 results in greater type II fibre glycogen depletion, attributed to the increased muscle force required to meet the higher resistance per cycle at the lower pedal frequency.
Practical Application
"Does riding at a low cadence work the fast-twitch fibres harder?" In 8 men riding 30 min at about 85% of aerobic capacity (crossover, muscle biopsies), 50 rev/min emptied type II fibre glycogen more than 100 rev/min at the same metabolic cost (49% vs 33% decrease, P < 0.05), while type I fibre depletion did not differ (46% vs 35%). This is the acute mechanism usually offered for low-cadence work; it is one session and not a training result.
Inference, not tested here: a hard low-cadence session draws more on type II fibre glycogen than the same metabolic work at a high cadence, so it may cost more fast-fibre glycogen before a following hard day; the paper did not measure recovery or the next session.
Limitations
n=8 men; training status not reported in the abstract; one session per condition.
Two cadences only (50 and 100 rev.min-1) at one intensity (about 85% of aerobic capacity) for 30 min.
Glycogen by histochemical optical density in one muscle (vastus lateralis), not whole-muscle glycogen; no performance, recovery or training outcome.
Abstract truncated in the database record; any further results are not available to this entry.
Seated or standing position, power output and the subjects' preferred cadence are not given in the abstract.
How this entry was checked and changed
Why this level
(mechanistic lab study with no performance outcome; n=8)