You'll notice one of the 3 sessions that comes out every week is titled "speed intervals".
"But i'm not fast!" "I have no speed!" "i've only got 1 gear!"
As with any running session you undertake, your measure is only against 1 thing - yourself.
Speed intervals are important for improving running for 2 key reasons:
Increasing leg speed & strength
The faster your legs move, the less time it takes to get from point A to point B. You're not trying to be the road runner, but some discrete increases in cadence and leg movement can go a long way over time.
Increasing cardio threshold
Just like a HIIT session, running faster at short intervals will improve your aerobic capacity.
For example: If it normally takes you 30 minutes to run 6 km at an average heart rate of 160, regular speed intervals can help you to run that 6km in 25 minutes at a heart rate of 160. Essentially you can do the same distance a bit quicker, but without extra effort!
We often find when we start a running habit, we'll do the same thing over and over. We'll run the same route, at the same intensity, for the same distance or time. A part of that is the instant gratification of the first run we do - it releases all these endorphins, you get that "runners high", it provides a benchmark we want to improve on, and hopefully it was safe enough that we didn't get injured. Naturally we want a repeat of that positive experience so we do it again. and again. and again. \
On the downside, like with weight training, repeating the same thing over and over will see some initial improvements, but an eventual plateau.
Speed sessions can be the missing link in breaking the 30 minute 5km barrier or getting the strength in the legs to conquer a 10km.
Some tips for speed sessions:
Try to find a pace that you can maintain for the designated time , but reach an 8/10 intensity by the end.
E.g for the week 2 speed session, theres 6 x 1 minute intervals. If you go out at 100% for the first 20 seconds, you'll certainly slow down in the next 20 seconds, and might be walking by the last 20 seconds.
If the interval lengths (e.g 1 minute) are too long, drop them down.
Just keep to the frequency (e.g 6 of them)
If you can't run at a faster speed, no worries!
With practice and repetition, you eventually will!