Torque-Cadence relationship and how it affects durability?

Durability in cycling is the ability to maintain a high level of performance (power output) despite accumulating fatigue over extended durations and repeated high-intensity efforts.

Durability can be defined as physiological resilience or fatigue resistance - in other words a rider's ability to withstand load and stress when work is accumulated over time. So basically being able to produce the same power numbers when fatigued late in a race, as in a fresh state early in a race!

Research has provided interesting insights into durability among different groups of riders, and it's quite clear the higher the level of the rider the better is the resistance to fatigue. World tour riders express superior durability compared to Pro Tours riders and elite pro cyclists have better durability than U23 elite riders.

As durability is measured as the loss in power output after a given amount of accumulated work, it's interesting to take a closer look at what defines power output, and find the mechanisms behind the loss in power.

Power is determined by the relationship between cadence and torque.

Power Output = Torque x Cadence

Torque is defined as the rotational force applied to the pedal, and cadence as the rotational velocity of the pedals.

So looking deeper into torque and cadence might explain where the loss in power comes from when a rider is in a fatigued state - does it come from a reduction in torque, cadence or both?

A recent study by Leo and colleagues looked into the torque-cadence relationship and how it affects power output in a fatigued state.

They had a group of male elite cyclists from a UCI Pro Team to perform a critical power test (a 15 seconds, 3 minute and 12 minute all-out effort) in a fresh and fatigued state, to see if torque and cadence could tell something about loss in power output.

To make sure the riders were fatigued they accumulated 2500 kJ of total work between the two tests including 5x8 min @ 90-100% critical power.

As carbohydrate depletion can have a negative impact on a riders durability, the riders had to consume around 90 grams of carbohydrate every hour.

What they found was that a significant drop in power output was seen in all 3 durations (15 sec, 3 min and 12 min) from fresh to fatigued state. Interestingly in the 3 and 12 min effort torque was the same, but cadence dropped significantly, thus a lower cadence was the primary cause of a decline in power output in a fatigued state.

The author concluded that their findings emphasize the importance of focusing on optimizing cadence to diminish the loss in power during prolonged races and training sessions.

So how does this relate to your training - how to work on your durability and implement these findings in your training regime, in order to improve race performance?

Let's look at how you can improve your durability..........

How to Improve Durability

• Long rides at endurance & tempo intensity (zone 2 & 3)

• Fatigue-resistance intervals (high-intensity work after prolonged efforts/accumulated work)

• Back-to-back hard training days (simulating race fatigue)

• Optimized fueling & nutrition strategies

Let's take a closer look at the fatigue-resistance intervals. Typically a session where you start out with some intervals then ride for an extended time, to accumulate a solid amount of work (around 2000-2500 kJ) before finishing off with some hard efforts.

A session could look like this:

• Warm Up: 30 min @ zone 2 (endurance pace) including a 4min ramp from threshold-intensity (zone 4) to VO2max-intensity (zone 5).

• Fresh-state Intervals: 3x4min VO2max (zone 5) with 4 min recoveries. RPM-target 90.

• Fatigue-building Endurance: 2-2½ hours of riding at the uppper part of zone 2 to low zone 3. You can add in a 5 min threshold effort (zone 4) every 20min to make it even more taxing. Make sure to fuel properly during this phase.

• Fatigue-state Intervals: 3x4min VO2max (zone 5) with 4min recoveries. RPM-target 90. Focusing on hitting the same cadence, and if possible the same power output, as in a fresh state.

• Cool Down: 15 min easy spin in zone 1-2.

From what we learned from the study on torque-cadence relationship, and how it affects durability, an important thing to focus on during the session is to aim for the same cadence in the fatigued-state intervals as in the fresh-state intervals.

You should expect a drop in power between the first and second set of 3x4 min VO2max, but try to dig deep and minimize the decline. A key aspect here is to fuel properly during the Fatigue-building endurance section. Aim for 90 grams of carbohydrate an hour.

References:

• Peter Leo, Borja Martinez-Gonzalez, Iñigo Mujika & Andrea Giorgi (15 Mar 2025): Mechanistic influence of the torque cadence relationship on power output during exhaustive all-out field tests in professional cyclists, Journal of Sports Sciences, DOI:10.1080/02640414.2025.2478354

  
  

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