High intensity interval training is one of the best ways to improve endurance exercise performance.
Not surprisingly, we put a lot of thought into making interval training as effective as possible: focusing on the intensity, duration and volume of the intervals. Whilst, these are all important factors, it’s easy to overlook one other key part of interval training…the recovery period.
Why is the recovery interval important?
So why is the recovery interval important? Firstly, the recovery interval affects the intensity of the work intervals. By breaking the workout into smaller intervals, we can complete each work interval at a higher intensity than if it was completed one longer interval.
However, there’s two ways we can look at the intensity of an interval training workout:
- Individual Interval intensity
- Average Workout intensity
As well as affecting the interval intensity, the recovery interval also affects the average intensity of the workout. In this way, we can adjust the recovery period, in order to manipulate both the work interval, and the average intensity of the workout.
Why is that important? Well, by adjusting the recovery we can alter the training effect, and the level of adaptation. In fact, for some interval workouts, the duration/intensity of the recovery period, is almost as important as the work interval.
One question that often comes up, is whether an active or passive recovery is best for interval training?
Essentially an active recovery involves continuing to exercise at a low intensity during the recovery. Whereas, a passive recovery involves almost complete rest.
Here, there’s two schools of thought:
- Those in favour of using passive recoveries, believe they allow a greater work rate during the intervals.
- Whilst, those in favour of active recoveries, believe that exercising at a low intensity, during the recovery can enhance recovery.
With this in mind, it seems logical that complete rest during recoveries, would allow for a greater workload during the intervals – but is this really the case?
What’s best? Active recovery vs passive recoveries
So, what does research tell us about using an active or passive recovery, during interval training?
One study, published in the Research Quarterly for Exercise and Sport (Lopez et al., 2014), looked at the effects of using a passive, or active recovery, on sprint performance during 6 x 30seconds cycling sprints. Since, sprint cycling requires a high level of recovery between sprints, you would expect the passive recovery to be superior.
Here’s the interesting thing: using a passive recovery only improved the sprint performance during the 2nd sprint. In contrast, using the active recovery, allowed the cyclists to better maintain power output, during the 5th and 6th sprints. From this, the researchers concluded that the active recovery, allowed cyclists to better maintain power output, when completing several sprints.
How does the length of recovery affect things?
One important consideration, is whether the length of recovery affects whether you should use an active or passive recovery.
In this regard, research has tended to suggest that passive recoveries may work better with short recoveries (25-50s). Whereas, active recoveries appear to work better when the recovery length is longer (100-180s) (Brown and Glaister, 2014; Ohya et al., 2013).
An important point here: these research articles looked at the effects of active and passive recoveries, following short duration intense sprint intervals. Not surprisingly, these require longer recoveries, in order to maintain the interval work rate. If you’re using longer intervals, completed at near to, or just below, VO2max intensity – such as 5k or 10k pace running intervals, or cycling FTP intervals at FTP – then using an active recovery is generally the best approach. One real advantage of using an active recovery is the way this increases the overall intensity of the workout.
At the end of the day, the choice of active or passive recovery, should be determined by the purpose of the workout, your aerobic fitness level and your chosen sport.
Different approaches for different sports
With swimming, active recoveries are generally less suitable, for practical reasons. To get around this, the recovery periods are kept much shorter. Which helps to push up the overall workout intensity.
In cycling, active recoveries are pretty much universal – regardless of the length or intensity of the interval. The real advantage here, is that with cycling it’s very easy to manipulate the intensity of the recovery, from very low to moderate.
With running, the choice of active or passive recovery, is largely determined by the length of the recovery. If the workout involves short intervals with a short recovery – such as 12 x 200m, off 25-30secs recovery – then a short passive recovery may be best. However, if you’re running longer race pace intervals – such as 6 x 1km at 10k pace – then an active recovery, often works better. The advantage here, is that using the active recovery, we increase the overall intensity of the workout. Which better replicates the physiological demands of the race you’re training for.
You can see just how much an active recovery increases the overall intensity of a running interval session in the table below:
|Interval session||Interval pace||Recovery|
Active vs passive
|Avg pace (inc recovery)|
Active vs passive rec
|6 x 1km (10k pace)||3:20/km||200m jog (60s) vs rest (60s)||3:34/km vs 4:10/km|
|5 x 1km (5k pace)||3:12/km||200m jog (90s) vs rest (90s)||3:47/km vs 4:24/km|
|5 x 1km (3k pace)||3:02/km||400m jog (180s) vs rest (180s)||4:07/km vs 5:07/km|
Aerobic capacity and interval recovery
A further consideration is your fitness level/training experience. In fact, your aerobic capacity (VO2max) needs to be considered when assessing which approach is best.
As a general rule:
- Active recoveries are a better choice if you have a high VO2max.
- Passive recoveries are generally more suitable if you have a lower aerobic capacity.
I’ve covered this in more detail here: Why athletes with a high VO2max need shorter recoveries.
Final thoughts on active vs passive recoveries:
Both active and passive recoveries are useful during interval training. Both have their place, with active recoveries more suited to longer intervals, and for those with higher levels of aerobic fitness. In contrast, passive recoveries can be effective when combined with short intense efforts.
For me, i’ve always found active recoveries to be most effective.
During cycle training, I only ever use active recovery – whether it’s between short sprints, VO2max intervals or longer threshold training intervals. With swimming, it’s always been the other way, and I only use passive recoveries – it just seems to work better. Whereas, with running training, I favour active recoveries for nearly all sessions. Having said that, I do sometimes use a combination of active and passive recovery – especially during sprint training, such as hill sprints.
Lopez EI, Smoliga JM, Zavorsky GS. (2014) The effect of passive versus active recovery on power output over six repeated wingate sprints. Res Q Exerc Sport. 2014 Dec;85(4):519-26. doi: 10.1080/02701367.2014.961055.
Brown J, Glaister M. (2014) The interactive effects of recovery mode and duration on subsequent repeated sprint performance. J Strength Cond Res. 2014 Mar;28(3):651-60. doi: 10.1519/JSC.0b013e3182a1fe28.
Ohya T, Aramaki Y, Kitagawa K. (2013) Effect of duration of active or passive recovery on performance and muscle oxygenation during intermittent sprint cycling exercise. Int J Sports Med. 2013 Jul;34(7):616-22. doi: 10.1055/s-0032-1331717. Epub 2013 Jan 16.