Have you ever measured your heart rate? Your heart rate is the number of times your heart beats per minute.
When you’re exercising, your muscles need more energy. To get more energy, oxygen is needed from the blood, so your heart rate increases to pump more blood. Regular exercise can improve your heart strength, so it’s more efficient and doesn’t need to beat so often when you’re not exercising. But fitness isn’t the only thing that can affect your heart rate.
The lowest recorded resting heart rate is 27 beats per minute. This Guinness World Record was set by Martin Brady in 2005 in the United Kingdom (Guinness World Records 2013). Most people’s heart rates are a lot higher – but there’s a lot of variation. The following table shows some information about heart rates – 90% of people have a heart rate faster than the ‘slowest 10%’ number, and only 10% have a heart rate faster than the ‘fastest 10%’ number.
|Age||Slowest 10%||Median||Fastest 10%|
Source: Fleming et al, Lancet 2011
You might notice that age and heart rate seem to be linked in some way. Correlation is a term used in statistics to describe two measurements or variables that are related to one another. For example, as children get older, their height increases. There is correlation between children’s age and their height. Correlation can tell you whether there is a pattern or a relationship between two measurements or variables.
When finding correlations, we need to be careful to make sure the two measurements or variables we are looking at make sense when compared. For example, it makes sense to compare children’s ages and their heights, and to say, “as children get older, their heights increase”.
There are other measurements that can be compared, but are likely to have no meaningful relationship. Even if there is a correlation, it could be due to chance. For instance, could you compare children’s height and their current hair length? Even if a correlation is found, it might not be true that “as children get taller, their hair gets longer”.
Your heart rate can be correlated with other things you can measure about yourself, such as your age and your blood pressure. From the table of heart rates above, we can say, “as children get older, their resting heart rate gets lower”. Can you think of other human body measurements that could correlate with heart rate? Could you correlate heart rate with your height?