Everyone loves to look at their stats after a training session, or even stalk their friends on Garmin and Strava to see how fast or hard they are training. Usually front and centre on these summaries is Heart Rate, shown as either an average, a max HR or a graph of HR over the session. It's something that if you are reading this post you have undoubtedly looked at but do you really know what it means or how to use it during your training or programming?
The most obvious place to start, what is HR? This might seem pretty obvious but stay with me because we will get a little more in depth in a minute. Heart Rate is a measure only of how many time your heart "beats", pushes blood out of it, a minute. Because it is only measuring one variable it is only getting part of the picture of how hard you are working. More beats = harder effort, and that is mostly true when you are comparing your own HR through a session. But what is not being measured is the amount of blood being pumped with each beat, "Stroke Volume", and this is just as important as HR when you are working out output.
In simple terms, people's hearts are different sizes and pump more or less blood per beat as a result. So when you compare you and your friend's HR graph at the end of the session you aren't comparing apples with apples. Although their HR may be lower and imply they were slacking off. They may have a much greater stroke volume and are in actual fact working at a higher output than you.
So in short, there isn't really a point in comparing your HR to anyone else's because you are only seeing half the picture. But, is there any point comparing your HR to other sessions or even using it during a session to gauge how hard your going?
To answer this you need to also know what effects HR and unfortunately its a longer list than just how hard you are going. Some of the most common factors effecting HR that most people would feel every day are:
Stress levels
Hydration level
Temperature
Illness
Nerves/anxiety
Caffeine
Previous exertion/level of recovery
Nutrition level
So with a list already this long of factors that impact your HR, it should be very conceivable that, turning up to training on a hot morning after a hard session the night before and a bad nights sleep, made up for with an extra shot of coffee making you dehydrated and maybe even anxious, you will have a different HR read out to the same session in the cold, with a good nights sleep and feeling fully recovered.
So given that HR is affected by so many variables, some of which are out of our control, why do we spend so much time looking at it? Why do we see elite athletes wearing chest strap HR monitors for every session and having sport scientists analyse their training?
For me, this is where HR monitoring becomes truly useful. When an athlete becomes "elite" or "professional" they have done so by, in many ways, turning themselves and their bodies into machines. They don't miss sessions, they don't miss sleep, they will eat properly and ensure their hydration levels are correct. They have coaches that monitor their workload and make sure they aren't getting sick or having 3 coffees before training and just as importantly they can push themselves to the effort being asked of them with consistency and precision. By becoming machine like, these elite athletes remove most of the factors that effect us mere mortals and our sensitive little heart rates. Leaving a HR graph where the read out is a much closer representation of the effort they are putting in session to session.
So is HR monitoring worth it? Ultimately it depends on who is being monitored and in my opinion for most weekend warriors probably not. It can be cool to look at, but definitely not something to govern your sessions by. If you're more serious about your training it starts to be more relevant but my advice is to spend less time looking at your watch for how hard you're working and more time worrying about paddling properly, surfing runners or even just looking up and seeing where you are going.
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