Threshold Testing in Cycling

Lactate Threshold is a concept that has gained significant acceptance in endurance training.  First, let’s get a few definitions out of the way:

Lactate Threshold (LT): is known by a few different terms, e.g. lactate threshold (LT), lactate inflection point (LIP), anaerobic threshold (AT) or Onset of Blood Lactate Accumulation (OBLA).  In practical terms, it is the point at which blood lactate is accumulating at a rate faster than it is processed by the body.  The significance of this point is it’s correlation with fitness/ metabolic efficiency.  With improved aerobic fitness, this point is reached at a higher exercise intensity (or power output).

Functional Threshold Power (FTP): is formally defined as the highest average power that a cyclist can maintain during a 40km timetrial, which equates to approx. 60min.  This average power output is strongly correlated to power at Lactate Threshold.

The significance of Lactate Threshold and Functional Threshold Power, is that the various energy systems in the body are engaged predictably at intensities related to the Lactate Threshold or FTP.  Different individuals will have slight variances based on factors such as muscle composition, training history, etc.

Why should you know your FTP?

The benefit of knowing this is that workout duration and intensity can be accurately prescribed in relation to FTP, so that the different energy systems in the body are stressed adequately to stimulate adaption.  When an energy system is stressed, then allowed to recover, it adapts and grows more powerful – the fundamental goal of training!

The following table from Ric Stern and British Cycling shows the physiological adaptions at different intensities.

Zone % of FTP Classification Physiological Adaptations
Zone 1 < 55% Active Recovery Muscular recovery and regeneration
Zone 2 56-75% Endurance Build endurance fitness and improve efficiency
Zone 3 76-90% Tempo Consistently sustain higher power outputs
Zone 4 91-105% Threshold Metabolic turning point that pushes threshold boundaries
Zone 5 106-120% VO2max Improving maximal aerobic power or VO2max limitations
Zone 6 121-150% Anaerobic Capacity Increasing maximum power outputs/ bursts
Zone 7 >150% Neuromuscular Stimulate more efficient neural activation

How should I use my FTP?

It is not well known, but performance in virtually every cycling discipline, apart from sprinting, is strongly related to FTP.  The higher your FTP, the better you can perform.  Even sprinters need an FTP that is high enough to get them to the finish line in contention to win the sprint.

So, FTP becomes the primary benchmark to assess your training improvements.  After that, each discipline (road racing, Time Trialling and Triathlon, MTB marathon, MTB Cross Country, track pursuit, etc etc) has unique demands on the other energy systems in the body.  Because these other energy systems can be targeted by performing intervals for a certain duration, at a certain percentage of FTP, you can use your FTP to set training workouts that maximize adaptions of the energy systems required in your event.  You can also assess your strengths and weaknesses, and target those areas that may be weaknesses, but are required in your chosen discipline.

How do I test my FTP?

The short, but not very practical answer is performing a 60min maximum effort timetrial.  Not many takers there!  This is not very practical for a number of reasons, firstly, it is incredibly hard, secondly most amateur (and a lot of professional) cyclists are not experienced at pacing such an effort, and will either start too hard and blow, or leave too much in the tank.

The commonly used field test is a 20min timetrial, and FTP is calculated to be 95% of the average power of this timetrial.  Again, many cyclists are not very good at pacing such an effort, and if it is their first ever test, there is a good chance that they will get it wrong. Performing the test indoors under laboratory conditions using a bicycle ergometer offers the easiest and most convenient way of performing the test.

To remove the need for the subject to pace the effort, for beginners or those who are currently unconditioned, a Maximal Aerobic Power ramp test can also be performed instead of the FTP test. The benefit of this test is that it removes the need for the subject to pace the effort and is shorter in duration. The downside is that it is not as accurate as the FTP test as it can be skewed by individual variances in anaerobic capacity.  FTP is around 72% to 77% of Maximal Aerobic Power, so initially it would be set at 75%.  The following table from Ric Stern and British Cycling gives an indication of the relationship between MAP and various disciplines.

Zone % of MAP Corresponding TT distance *
Zone 1 60-68% ≥160km
Zone 2 64-72% ±80km
Zone 3 72-77% 40km (1 hour) / Predicted FTP
Zone 4 75-81% ±15km
Zone 5 89-91% 4km
Zone 6 >91% ≤3km
* Based on world class performances

 

Now What?

The design of a training program is beyond the scope of this article, but in practical terms, knowing your FTP allows you to perform CycleZone workouts appropriately, because each workout is designed to provide intensities based on FTP, not on absolute wattage making it totally individualised.  As a result, two individuals who may have very different FTP’s will still perform exactly the same workout based on FTP with the same stress and adaption to both individuals. Therefore training is quality focused.

Contact CycleZone Performance Lab at info@cyclezone.co.za should you wish to book an appointment with a Sport Scientist to conduct your FTP test. Current pricing is R350 which includes a Body Composition Analysis and introduction to training with power, it takes approximately one hour.

Article by Bruce Diesel – Head Coach at CycleZone

www.cyclezone.co.za

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