The most useful way to utilise a heart rate monitor when training is to workout within specific Heart Rate Zones, based on percentages of your Maximum Heart Rate..
|% of Maximum Heart Rate
However, you’ll find that the sport you do, and the plan you’re following will often give you different ranges from above. That’s ok. My suggestion is to follow the plan you’re following, and don’t mix methodology. The most important thing is that you know your maxHR:
Calculating Your maxHR
If you want to know your maximum heart rate, the best way to find that out is to do a specific test on your rowing machine designed to take you to maximum effort and maximum heart rate (there’s an example of this below).
However, some people just don’t want to ‘go there’. So the alternative is to use a formula based on your age. As a general population guide, it’s ok. But it can be off by at least 10bpm for a lot of people – and for some ‘outliers’ it can be massively off. So if you’re serious about Heart Rate Zone training, PLEASE do a proper step test as described below.
If you want to check what your HR zones would be based on your age though, here is a calculator for you. Using this formula to calculate your maxHR isn't an exact result. It may be off by 10bpm. The only way to know for sure is to do a test
If you want tp do a proper test, the Australian Institute of Sport have designed one. Read the full article here.
Heart Rate Step Test on Rowing Machine
The test is very simple. Based on your most recent 2K pace (or an estimate of it), you do seven 4 minute steps starting at a low power (slow pace) and increasing by a set number of watts for each step. You start recording your heart rate and you do the first 6 steps without a break and the sixth step is about 5 seconds slower than your 2k pace. After 24 minutes of rowing, that pace will feel pretty hard and your heart rate will be reasonably high.
At the end of the 6th step, you take a 1 minute rest and get ready for the fun part. At the end of the one minute rest, you do a racing start and row as fast as you can for four minutes. This step should be at or faster than your 2k pace. At the end of that step, you review your HR data for the highest value sustained for 5 seconds. Use that as your maximum heart rate.0