I wanted to share my heart rate graphs from 2 different runs that I did recently, because I love to geek out over this sort of thing! Both sessions were 4x1km, but one was a threshold workout and the other was an interval session.
The threshold session is at a slightly slower pace (close to half marathon race pace for me), but with a shorter recovery and the interval session is faster (at 5km race pace) with a longer recovery.
The threshold session is at a slightly slower pace (close to half marathon race pace for me), but with a shorter recovery and the interval session is faster (at 5km race pace) with a longer recovery.
My coach explained to me in an email afterwards that an interval session is effective if you spend at least 12 minutes in the correct heart rate zone, but during a threshold run you want to be in the threshold heart rate zone for a minimum of 15 minutes.
I don't know my maximum or resting heart rate, so I don't know exactly what the numbers are for each zone. But it's pretty easy to see the trend - during the threshold intervals my heart rate didn't have a chance to drop very low, so it climbed back higher quite quickly. Whereas my heart rate dropped a lot lower during the recovery of the interval session, but then went higher during the rep.
This is a good example of how you can keep your training simple. You can give your body varied stimulus without needing to come up with super elaborate sessions every single time!
I don't know my maximum or resting heart rate, so I don't know exactly what the numbers are for each zone. But it's pretty easy to see the trend - during the threshold intervals my heart rate didn't have a chance to drop very low, so it climbed back higher quite quickly. Whereas my heart rate dropped a lot lower during the recovery of the interval session, but then went higher during the rep.
This is a good example of how you can keep your training simple. You can give your body varied stimulus without needing to come up with super elaborate sessions every single time!