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High / low repeats

high-low-repeatsAim of Session

Blocks of high and low cadence within an endurance ride

Session description

WARM UP: 15 minutes of zone 2, included in session time

MAIN SET: Perform 1 x 10 min of low cadence (~50-60rpm) and 1 x 10 min high cadence (~110-120rpm), 5 mins between. Repeat once more, keeping HR in zone 2.

COOL DOWN: 15 minutes of zone 2, included in session time

Physiology

As explained in other sessions within this section, different cadences mean different contraction speeds. The human body is able to cater for these speed variances because it has different muscle fibre types suited for the the work requirements. The slow twitch muscle fibres are recruited at low forces and low contraction speeds; the fast twitch fibres are recruited at high forces and high contraction speeds. In reality, rather than discrete pools, there exists a continuum of fibre types. This is good news for the cyclist as repeated training means we can shift the fibre's characteristics towards more aerobically trained (slow twitch) or anaerobic / power requirement (fast twitch) using clever training techniques. Ordinarily, a cyclist will ride at what scientists call their Self Selected Cadence (SSC) - interestingly, the research has shown this isn't necessarily the most efficient cadence (in terms of oxygen used per watt of power).Whilst "fast pedal" and "cadence pyramid" sessions teach a rider to access novel muscle fibre pools, this session improves the repeated contraction of those fibres, allowing them to develop the characteristics associated with endurance capacity.

Application for the Rider

This session forces a rider to work at cadences at the very extreme ends of their cadence range: the low cadence work will be useful when gear choice isn't possible i.e. up steep climbs; the high cadence work will recruit rarely used muscle fibres and enable their aerobic development. Its akin to a carpenter having many tools in their workbox - the more skilled a rider is in using low, medium (SCC) and high cadences, the more versatile they become and better equipped to all riding / racing scenarios.

Practicalities and tips!

  • Possible on the road as well as on the turbo - depending on experience level of the cyclist, a flat or more varied terrain route can be chosen for this session
  • You will notice that to keep a zone 2 heart rate across the blocks, you will need a higher power for the low cadence block (maybe 10 to 20W higher than your normal LT riding intensity) and a lower power for the higher cadence block (upto 30W lower than normal LT powers). Experiment, you have 2 blocks of each to trial it!

Evaluation of the session

  • How well did you keep your heart rate at LT intensity in this session?
  • What was the difference in power across the high and low blocks?
  • Look within each block - were you able to stabilise your heart rate, or did it climb across the 10 minutes?
  • How did the powers and heart rates compare from block 1 to 2 at the same cadence?
More in this category: « Fast pedals Hill revs »