Similar to tempo run, cruise intervals improve your lactate threshold (occurs around 85% of your maximum heart rate) but a short rest between repetitions allow you to run slightly faster than a tempo.
You may also use the same pace as your tempo run but reduce the rest time in between repetitions.
Threshold run helps improve your aerobic capacity and race time.
It is also suitable for beginners before they transition to longer tempo run.
Pace consistency and rest is the key of cruise intervals training.
So how to know if you’re having a good cruise intervals session?
1) Is Your Pace Consistent?
Your average pace (Avg Pace) should be very similar for each repetition.
In your Garmin Connect, go to “Splits“.
The data above shows that the runner could be going too fast (4:33min/km) in the 3rd repetition.
Aside from the average pace, you can look into the pace consistency within each repetition.
After zoom in, you can use your mouse to drag (that’s why data analysis is often better done with desktop instead of mobile devices) and further highlight any repetition to check your pace consistency.
2) Is Your Running Form Consistent?
Running form often associates with your Cadence and Ground Contact Time (only available if you’ve heart rate monitor chest strap or running dynamics pod).
In the picture the cadence (187, 187, 186, 184) is reasonably consistent for each repetition.
You may be curious why 3rd and 4th repetition time are faster than 1st and 2nd repetition even with lower cadence.
The reason is because 3rd and 4th repetition has a longer average stride length.
If you have more advanced running data like ground contact time (GCT), you can see if your GCT is consistent.
The picture shows that the 3rd and 4th repetition has a slightly higher GCT (211 for both) than the previous 2 repetitions. In fact the runner feels the fatigue in the 3rd repetition. This could be due to lack of strength or the inefficiency in muscle fiber recruitment.
If you look at all 4 repetition GCT, they are all above 200 millisecond which occurs on most leisure runners. As a reference elite runners typically have GCT below 180 ms.
To improve GCT, a runner can do drills like rope hopping. Stride (short sprint) can also be integrated after your easy run to strengthen your Achilles.
3) How Do You Feel?
As with other types of training this an important question after each workout.
During cruise intervals breathing is often on the verge of out of control but you should feel under control and able to hold for few more minutes.
If you feel “comfortably hard” and able to take a selfie ;p at the end chances are you’re having a good session.
Remember to keep yourself hydrated during the rest.
What pace I should be running?
You should be doing your cruise intervals at your 5-10k race pace, assuming the weather is good.
If you’re doing it for your first time, you can utilize Jack Daniel’s VDOT Running Calculator. Enter your personal record and calculate the pace you can use for your training (under the “Training” tab).
What can you do if you feel too tired during the workout?
It is not unusual that you may feel fatigue before the last repetition especially when you try something new, eg longer distance or more repetitions.
In such situation you can run at slower pace but make sure you maintain each rest time.
To design a good cruise intervals training, you can manipulate 3 elements:
- Distance/time of each repetition
- Rest time in between repetition
In the case study above, before the session starts the runner extended the rest in between repetition to 2 minutes instead of 90 seconds due to the hot temperature at 34℃.
This rest time extension allows the runner to maintain the pace and completed the workout.