Why Measure Power

I have been interested in monitoring performance metrics for a long time. That’s why I started HeartRateMonitor.co.uk in 1999 since rebranded to CardioCritic.com. Measuring your speed/pace, distance. time and heart rate are all very useful metrics. They can be used to monitor progression with regard to competitive status, fitness level and recovery state. However, with all these metrics, there are external factors that can affect and influence the results. e.g wind, elevation, altitude, personal well-being etc.

Power is Absolute

That’s where POWER is different. Power is an absolute measurement that is the same whether you’re riding uphill, downhill, in to a headwind or pushed along by a tailwind. It is not affected by your physical well-being. 200 Watts is 200 Watts which is why POWER is a brilliant metric for monitoring progression ….

Monitor Progression & Improvement

Monitoring your power output is a quantitative and repeatable way to measure how hard you are training. Power can be the benchmark figure that all other metrics are measured against. Cycling the same route at a given average power is a convenient way of monitoring progression. If the average power from successive rides is similar (+/- a few watts) and your average heart rate is dropping … you are getting fitter, irrespective of the finishing time (which can be affected by weather etc). Your body is producing the same levels of power with less effort on your cardiovascular system – conclusion being an increase in fitness levels and cycling efficiency.

Over-training Warning

Conversely, riding the same route at a similar average power with an increase in average heart rate (more than +5bpm) on successive rides could be an indication of over-training. If you don’t have a heart rate monitor then you can judge over-training by the RPE scale (rate of perceived exertion). When you’ve been riding with a power meter for a few months you’ll get to know what 175 watts at 85 RPM (cadence) should feel like with regard to effort. If you are finding it harder to push out power values that you’d normally feel comfortable at then maybe it’s time for a rest.

Riding within your limits

As you get used to using your power meter you will know how long you can sustain certain power levels. One of the first tests you will / should perform is an FTP test, Functional Threshold Test. Once you know your FTP then it is possible to ride with % of FTP on your bike computer display. For example, riding in Power Zone 2 (55% to 74% of FTP) will benefit your ENDURANCE. Spending short quality time in Zone 5 (VO2 Max – 105% to 120% of FTP) will see increases in maximum power and short sprint speed / performance

More Reading

The following external resources offer a further insight in to the benefits of training with a power meter