THE STRONGEST SCIENTIST
Go with your heart.
It’s the last day of the ABSA Cape Epic, which starts in Wellington and finishes at Val de Vie. It’s most definitely not all downhill from here, as the day starts with a brutally long climb right to the top of Du Toitskloof Pass.
I give it absolutely all I have on the uphill, sweat pouring down my face, panting with the effort. I’m on the proverbial limit.
Not a new experience, this week; however, a quick look at my heart-rate monitor, and the readings are very different from what they were in the first few days of the race. Alarmingly, my heart rate is only 135 bpm – at this level of intensity, my heart rate would normally be closer to 165 bpm.
Thankfully, experience has taught me that this is one hundred percent normal.
Heart-rate monitors have become extremely popular with gym-goers. But – besides the fact that most modern optical heart-rate monitors are often woefully inaccurate – your actual heart rate, even if accurately measured, is rather insignificant.
Let me explain. Your heart rate is an indication of training intensity. The higher your training intensity, the higher your heart rate. As your fitness level increases, you would expect your heart rate to become lower at a specific relative intensity.
However, tracking this is not as easy as it may seem. The caveat here is that on any given day, your heart rate may be up to 10 beats higher or lower, simply due to common day-to-day changes. Quality and quantity of sleep, stress, tobacco, caffeine, recent or current illness, temperature and current fitness level are only some of the factors that may skew your results.
At any given exercise intensity, therefore, you can expect a range of heart rates, depending on these factors. Because of this variability, interpreting your heart rate becomes more complicated than you might imagine.
For example: acute fatigue, stress or lack of sleep often result in higher heart rate, whereas a more chronic response from a high training load would result in a decrease in sympathetic activity (“fight or flight” responses), and an increase in parasympathetic activity (“rest and digest” responses), which would lower your resting and sub-maximal heart rate.
What is commonly experienced during stage races – as I did, climbing to the top of the Pass on the last day of the Epic – was a decreased sympathetic response, thanks to seven hard days of racing. It was certainly not an indication of increased fitness levels.
Changes in heart rate due to improvements in fitness may not be as large as in this example, however. So how do we accurately monitor whether or not we’re moving in the right direction?
A recent systematic review by Saw and colleagues published in the British Journal of Sports Medicine compared the usefulness of objective measures (such as heart rate, and other intrinsic physiological values), and subjective measures (such as athlete self-reporting of wellness, fatigue and effort). The review found that subjective reporting of well-being was in fact more sensitive than from objective measures.
What does this mean for you? Well, if you perform a sub-maximal effort, then simply asking yourself how it felt, or rating your perceived effort, might give you a better idea of your overall progress than looking at your heart rate or any other objective physiological marker.
So again, my message is: go back to the basics, and learn to appreciate how you’re feeling while you’re training.
Gauging yourself using your own perception may be one of the best indicators of overall progression in fitness.
“Simply asking yourself how it felt might give you a better idea of your overall progress.”