Training with Power: what’s the fuss?

BY IN Exercise Institute News On April 29, 2015

Why train with power?

Power meters are now common in the world of cycling, from the professional to club or weekend rider. But do many of us really understand their use and purpose and how the power meter helps to improve the performance of a cyclist?

We address the following questions: Why is training with a power meter important? What are the different training zones defined by power output? What physiological events occur at these different intensity outputs?

Understanding the answers to these questions will help you get the most our your training time and define the concept “quality over quantity” when applied to cycle training.

What is all this hocus pocus pertaining to power meters?

A power meter itself will not make you go faster. It will cost the same as a good set of fast wheels but will not generate any further propulsion for a given effort.

If this is the case, why would we use one if our ultimate goal as a cyclist is to go faster for longer?

The answer is simple: a power meter is the only device on the market that will outline and track effort specific to your individual fitness level and assist in developing training specific to your goals.

With a power meter you and your coach will be able to detect small changes in fitness. This analysis is not only highly motivating to an athlete but essential in mapping future training specific to individual fitness and goals.

There are currently a range of power meters on the market at varying prices but all provide one message: that the power meter is an accurate reflection of the individual athlete.

Power training zones

You will see power data displayed in different training zones:

Zone 1
Zone 2
Zone 3
Zone 4
Zone 5
Zone 6

These zones are approximated as a percentage of your Functional Threshold Power (FTP).

There are several methods to identify your FTP.  An athlete can complete a 20 minute maximal effort or through internal measures such as Lactate threshold or Ventilation threshold.

This measure of ‘threshold’ seeks to identify the point where the human body can maximally sustain a given output for an extended period of time.

FTP is what largely determines performance in endurance athletes and best responds to specific training exercise.

It is also positively correlated with measures in the athlete’s fitness, performance and overall well-being. It is an accurate representation of the true ability of an  individual.

Therefore, an increase in FTP is an increase in fitness and performance. We use  information derived from a power meter and to put in place a training platform targeted at increasing FTP over a given time.

Utilising power zones

Within a lab environment we are able to measure other aspects of exercise functioning and over lay them with a power meter to examine what your body is doing.

We will explain why training zones are important to human exercise in light of a laboratory test administered to ascertain a cyclists lactate threshold. 

LT and Zones

Lactate (blood), Oxygen (Vo2), and Heart Rate during an incremental exercise test: 50w increases every 5minutes (see bottom axis). Left side axis represents Lactate accumulation, right side axis represents heart rate

The above graph represents a Vo2 max test where Blood Lactate (La-mmol/L) Litres of Oxygen (Vo2 L/min), and Heart Rate (b/min) are tracked along a scale of 50w increments (bottom axis).

The left axis represents lactate accumulation in mmol/L and the right axis heart rate in beats per minute. Both heart rate and oxygen consumption both rise linearly across increasing linear amounts of exercise (50w steps).

Notice that lactate levels tend to rise minutely at first until a sharp increase, just prior to the end of the test, at the 400watt mark. The lactate line or curve is the main interest here.

Approximately 4mmol/L is a benchmark for threshold when measuring lactate levels. This point is approximated by the dashed line at the 330watt mark intersecting the lactate curve.

Thus the individuals threshold is said to occur around the 330w mark. This is also representative of their one hour of power effort, or maximal one hour output.

This point occurs at a different wattage dependant on fitness, mass, and genetic factors for every individual. Importantly it has been measured internally. This figure tends to correlate resonably well with FTP and is often refered to as an individuals one hour time trial output.

What does each zone reflect when training

Coaching-Services-1

Dylan Humbert, known to have little regard for his lactic thresholds

Once the FTP  is established the training zones are calculated from this figure.

Each zone is associated with a different  aspect of internal functioning.

Zone 1 and 2 are warm up or recovery pace

Zone 3 has a small increase in lactate compared to Zone 1 and Zone 2, but is not accumulating enough lactate to really drive maximal lactate clearance adaptation.

Zone 4 represents the “lactate threshold training zone”. Time spent at this zone assists the body in adapting to maximal lactate clearance as a measure; how long you can go for over a long distance (20-90mins).

Improving Zone 4 means more watts can be produced for the same amount of lactate.

In a bike race,  a time trial or when riding with friends you may feel lethargic and can no longer sustain the pace. This occurs when too much time is spent at or above Zone 4.

Zone 4 is critical to cycling improvement. It represents the power zone that illicites a sharp increase in lactate, and forces the body to deal with this accumulation.

Training above this may be training too hard and result in sudden fatigue and training below this may not be specific enough if improvement gains are what you seek.

If we focus on improving this mark at Zone 4, we will see fitness gains and increased performance.

Zone 5 is a critical zone and represents a maximum 3-5min power output, or Vo2max power range. Time spent at this output range illicits a sharp reduction in oxygen saturation in the body concurrent with the maximum oxygen uptake through the cardiorespiratory system, facilitating VO2max.

So shorter high intensity intervals can be completed in Zone 5 resulting in very concise adaptation to a demanding stimulus requiring large amounts of oxygen for metabolism. Notice in this zone lactate levels are very high thereby making the time to exhaustion imminent and not sustainable. Thus it is well above ones threshold.

Zone 6 is anaerobic capacity power and can only be completed for periods of around 1-2minutes at a time and produces excessive lactate. When training at high intensities the time spent at that intensity is reduced. So 6x 2min efforts at Zone 6 allows for 12mins spent at anaerobic outputs, compared to 4x 10min efforts at Zone 4, where 40mins is spent at a maximum lactate clearance output.

It is important we recognise that not all exercise is linear in effort.  Exercising at 175watts, in the case of the cyclist portrayed in the graph is not half as hard as exercising at 350watts. 350watts involves dealing with a 4-fold increase in lactate compared to 175watts. 300watts may be more accurate to finding an effort ‘half’ as hard as 350watts. An accurate calculation of your FTP is crucial to tailoring your training for this purpose.

Using power zones in your training

Once you have your FTP and your training zones, the nature of your training will depend on the outcome you desire and the activities you are training for.

If you are having difficulty finishing hard rides or races or want to improve your cardiorespiratory fitness then training in Zone 4 is optimal (5-20min efforts). An athlete would include one session in Zone 5 (3-5min efforts) to facilitate a good adaptive stimulus to improve fitness.

If you want to increase explosive power for short hard efforts, like winning a sprint on a ride or finishing well in a race, then training in Zone 6 will make your body adapt to the demands of excessive lactate levels during exercise.

theo

Theo Yates of Navitas Satalyst Racing is a master of massive lactate accumulation, seen here winning the sprint in spectacular fashion

 

The information is specific to any individual regardless of ability, gender or exercise status and represents the importance of accurate measurment of an individual’s output.

Regardless if you are training for health, fitness, performance, or to be the best athlete you can be, accurate measurement of your bodys’ ability is of the upmost importance.

A power meter and accurate FTP and power training zones will ensure your training is targeted and specific to your individual fitness and desired outcomes.

Creating a program specific to this information will give your training meaning and purpose and quality. Each training session has a purpose aimed at reaching your long term goal.  Quality over quantity will deliver success by utilising the equipment and knowledge at our finger tips.

Hall Cycling supplies and installs Infocrank power meters
More information about Infocrank can be found here

This article is published by Brad Hall

-Brad has a degree in Exercise Science and Psychology (Hons.) AMAPS


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