The first sportive of the season (Kentish Killer) is less than a month away and the rain is seriously hampering outdoor rides, so most of us are cycling indoors at present, either on Turbo’s in the garage, stationary gym bikes or taking spin classes. To get the most out of this type of training it is vital to train at the correct intensities and monitoring heart rate is the easiest and cheapest way to do this. However, there is a lot of misconception about heart rate training zones and using inaccurate ones means wasting time and even decreasing fitness. Hopefully, this blog will help to clarify some of these misconceptions and improve your training sessions.

Physiological basis of heart rate monitoring

The only true way to measure intensity and work rate is in a laboratory, measuring oxygen consumption and carbon dioxide output via a face mask, which is impractical for every training session. However, the more intense the exercise the greater requirement of oxygen to the muscles which requires the heart to beat harder to supply that demand and thus by measuring heart rate we are indirectly measuring oxygen consumption.

Without testing there are some common equations that estimate the maximum intensity and heart rate;

220 – Age

The standard way of working out heart rate zones is to use the 220 – age equation to give a maximum heart rate (MaxHR) and then multiply by 40%-80% (sustainable aerobic to approx. lactate threshold) to get the desired intensity level. This calculation can still be found on gym aerobic equipment charts but it has some major flaws;

Firstly, it assumes that every person of the same age has the same fitness level and/or the same maximum heart rate. Secondly, it doesn’t take into account the resting heart rate, and assumes it is zero (which would be death!) and thirdly, has been proven to be wrong by +/- 20 bpm.

For example, using this equation my MaxHR is 220 -42 = 178 beats per minute (bpm) and thus my 40%-80% cardiac zones would be 71 - 142bpm. However, in a lab test, my MHR is 191 and my lactate threshold is 168 bpm (87% of MHR). If I had trained based on the 220-age equation I would have decreased my fitness quite dramatically.

A more specific way is to use the Karvonen formula which is based on your estimated MHR but also factors in the resting pulse rate. This is known as the Heart Rate Reserve formula and is a little more complicated to work out:

Using this method my Heart Rate Reserve training zones would be calculated as below:
(220) - (your age) = MaxHR
(MaxHR) - (resting heart rate) = HRR

(HRR) x (40% to 80%) = training range %
(training range %) + (resting heart rate) = (target training zone)
so,
220 – 42 (age) = 178 (MaxHR)
178 – 54 (resting pulse) = 124 (HRR)

124 x .4 = 50 (40% training percentage)
124 x .8 = 99 (80% training percentage)

50 + 54 = 104 (target training zone, in beats per minute)
99 + 54 = 153 (target training zone, in beats per minute)

Thus my 40%-80% cardiac zones would be between 104 – 154bpm. A slight improvement on the 220 – age equation, but still not accurate enough to use as a training protocol compared to Laboratory testing.

For the unfit these cardiac zones are a good estimate, but for anyone who is looking to improve their cycling or running performance there is a need for a greater degree of accuracy to maximise the effects of training sessions. Apart from laboratory testing, there are a number of sub maximal tests that have proved to be significantly more accurate than the above equations. Tempophysiotherapy use the Carmichael 8 min test which has been validated to laboratory tests to be statistically significant.

Using this test my MaxHR was 189bpm and lactate threshold calculated at 166 bpm, both within 2bpm of the laboratory test and far more accurate than the equation formulas.

All that is needed is a stationary bike, a heart rate monitor and interpretation and calculation of the results which Tempophysiotherapy can provide. From this we can use specific cardio zones to target training to your needs or weaknesses such as hill climbing or riding faster for longer in a group, and we will provide specific workouts to improve these areas so you train smarter not longer.

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