PHYS-16 · Principle

Do low-cadence intervals train my fast-twitch fibres?

Fibres join small to large as force rises, so high torque brings in more. Whether low cadence at equal power does is unsettled; low-cadence training gave no clear extra gain.

How the body works, agreed across the reviews below; a study entry shows what one experiment measured.

established physiologyApplies to everyoneEstablished — small-to-large recruitment among motor neurons that share a drive, in shortening and lengthening contractions (Hug et al. 2023; Duchateau & Enoka 2016), with exceptions in some natural, fast or…

Practical Application

Do low-cadence intervals train my fast-twitch fibres? Fibres join small to large as force rises, so high torque brings in more. Whether low cadence at equal power does is unsettled; low-cadence training gave no clear extra gain.

What it means for training: pick cadence work for what it trains (torque, race cadence) and judge it by the session's targets (SYNTH-56, SYNTH-82); a systematic review encourages varied cadence and recommends no range (REF-255).

What it does not mean: that low cadence builds type II fibres or strength by itself (no strong evidence of benefit in 7 studies, REF-117); 49% vs 33% type II glycogen loss at 50 vs 100 rev/min is REF-1074's result in 8 men, one session.

Mechanism

Motor neurons with a common input are recruited from small, weak units to large, forceful ones; reported reversals fit clusters of shared input, not whole muscles (Hug et al. 2023). The order holds in lengthening contractions, with lower firing rates (Duchateau & Enoka 2016); in natural movements it can vary with the muscle's mechanical job (Hodson-Tole & Wakeling 2009).

After cycling below VO2max, slow-twitch fibres lost glycogen first and fast-twitch fibres were drawn in as work went on; above VO2max both worked from the start; 30-120 rev/min did not change the pattern (Gollnick et al. 1974). From 43 to 91% of VO2max, more type II fibres were active from the start (Vøllestad & Blom 1985, 5-7 per group).

At a given power, muscle activation varies with cadence, its minimum moving higher as power rises (REF-237).

Common misreading

"Low cadence is strength work"; "I fade late because my fast-twitch fibres are gone".

Backs

SYNTH-82 "at the same metabolic cost, 50 rev/min emptied type II fibre glycogen more than 100 rev/min (49% vs 33%) in 8 men" (one study; an older one found no cadence effect) · SYNTH-23 "the energetically optimal cadence fell after 55 min of cycling in 14 experienced cyclists, read as more type I fibre contribution" (the authors' reading) · SYNTH-56 "High cadence at high intensity impaired neuromuscular function more than low cadence, and no cadence range can be recommended"

Sources

Hug et al. 2023 · Paper ↗

Duchateau & Enoka 2016 · Paper ↗

Hodson-Tole & Wakeling 2009 · Paper ↗

Gollnick, Piehl & Saltin 1974 · Paper ↗

Vøllestad & Blom 1985 · Paper ↗

Mater, Clos & Lepers 2021 REF-255 (A-) · Paper ↗

Hansen & Rønnestad 2017 REF-117 (A-) · Paper ↗

REF-1074 (C+)

REF-237 (B)

REF-261 (B)