Heart Rate and Power: A Dual Relationship

Over the last 10 years as power meters have become more readily available and more affordable, more people than ever are able to have access to this great training tool.  
But does having a power meter mean that the trusted heart rate monitor is no longer needed?   

The simple answer is NO

Below are a few brief points exploring the differences and relationship of both HR & Pwr.

1) Power provides very precise measurements of the AMOUNT of work you are   doing in your training.  Heart Rate provides the measurements of the body’s RESPONSE to the amount of training being done.  

2)Power allows establishment of a baseline FITNESS which can be improved with training. Heart Rate establishes a baseline HEART RATE which cannot be improved. It is the power that is the quantifiable measure of FITNESS when  compared against the baseline HEART RATE

3) Power allows for very EXACT training zones to be set because ultimately, 1 watt = 1 watt. Heart rate only allows for GENERAL training zones due to the many variables which can affect the body’s RESPONSE to pushing the watts. eg. Fatigue, tiredness, stress, lack of sleep, cardiac drift or even too much caffeine etc. 

4)Power allows MEASUREMENT of MICRO changes in fitness. Heart will MEASUREMENT of LARGE changes in fitness.

5) Consistent retesting will lead to increased POWER TRAINING ZONES which ensures progressive overload throughout a training plan, in turn creating greater AMOUNT OF WORK output on the bike. Once the baseline HEART RATE has been established, retesting may only show a change of 1 or 2 bpm but will not show vast changes. Therefore, if consistently training only with heart rate, this means that over time you will feel fitter but not neccessarliy be getting stronger progressive overload to train harder has not  been possible due to lack of INCREASED Power Training Zones. 


Power is the ‘AMOUNT‘ of what you a pushing on the pedals, and Heart Rate is the ‘RESPONSE‘ to pushing.  But it is important for a coach to be able to track both measures in training, especially when there are questions such as ‘I could push 240w yesterday no problem and today I struggled to hold 200w’, and heart rate becomes the first point of call to start investing the answer.