What are Intervals and Repetitions (Reps/repeats) and what’s the difference between the two?

Although associated with middle distance and long distance track running training both repetitions and intervals are great for increasing speed and endurance and I see no reason why all runners can’t adapt these workouts to get benefit.

Runners use these terms repetitions and intervals interchangeably, but there is a difference between the two. In both cases you run over a specified distance and the runs are broken up by a recovery jogs or standing rest. And, unless the session is designed to be at lactate threshold (endurance based) session then the jog will be a very slow jog (just above a walk).

The distinction between intervals and repetitions relates to the jogs or standing rest between each run and to some extent the length of the run.In an Interval session the time spent jogging / standing rest is kept constant ranging from 2 to 3 minutes — usually too short to allow complete recovery. Therefore a session could be expressed as follows:

5 x 1000m with 2 minutes recovery (standing/walk or jog)

With a session like this you would have your recovery near the start of the next run so that runners can do their own recovery in preparation for the next run. Some might need to stay standing while others are able to jog depending on their fitness levels. With such a session you would look to maintain a pace eg 10k race pace but reduce the recovery. A 36min 10K runner would run the mile runs in around 5.40 to 5.50 minutes. Once your average started to get quicker, then you would look to reduce the recovery down and maintain the pace until you got the recovery down to 60secs as a minimum.

During my completive days when I was able to complete 10K cross country races in around 30 minutes or just under I recall with great clarity a weekly session of  5 x 1 mile with  3 mins recovery where I was averaging well under 5 minutes for each effort.

The goal for interval training is to “accumulate” time spent running at a very high level and increase our body’s ability to adapt and eventually run at a sustained, higher anaerobic pace for longer periods.  

For interval workouts, a general guideline for the amount of recovery time between runs should be equal to or less than the time spent running. For example, if we’re running  interval 800s at 4 minute pace, then the recovery time would be 3 minutres.

When designing interval workouts, I tend to choose distances ranging from 800 meters to 2000m (runs ranging three to six minutes). 

The challenge and the benefit of running intervals always comes back to controlling the recovery time, not running faster.

Below is a guide to some interval workouts

50 min 10K runner 5 x 1000m 2 mins standing rest Aim for average of 4mins 42 Running at 47 min 10K pace
45 min 10K runner 5 x 1000m 2 mins standing rest Aim for average of 4min 16sec Running at 42.39 min 10K pace
38 min 10K runner 5 x 1000m 2 mins standing rest Aim for average of 3min 37 Running at 36.09 10K pace

You sometimes also here the term speed/endurance. This is where the runs are less than 3 minutes so you might be doing 800m or 600m or 400m repetitions but without ample recovery but at race or faster than race pace. Track runners like Sebastion Coe used this type of training. For instance he would regularly run 6 x 800m on a road loop with 60 to 90 seconds standing rest. He would run these at his 1500m pace ie in under 2 minutes!

With Repetitions (or Repeats or speedwork)  there is a  greater emphasis is placed on hitting times faster than your race pace for each fast run with recovery  adjusted so that those times can be hit, normally expressed in terms distance covered.

Because we are running fast the distance run is generally shorter e.g., 200s, 400s, 600s so that we can repeat themmultiple times. The objective is to “repeat” the distance with the same quality at the end as at the beginning of the workout. We are literally training our body to be able to run at a faster than race pace improve our anaerobic capacity, develop new muscles, build speed, and make us familiar with more rapid, efficient, and fluid leg turnover and be able to relax and feel comfortable at race pace.

Designed for the track runner a 4 minute miler would run 4 x 400m in 56 seconds with 400m jog. He would be running his maximium speed but he would set ample recovery for setting off again. Recovery guidelines for repeats/reps are generally two to four times the amount of time spent running the repeat

Repetitions are sometimes broken down into sets making the work more manageable, making it a hybrid between Repetitions and Intervals. An example would be 3 (3 x300m with 100m jog)500m jog between sets. Notice that the job between sets is long allowing the runner to recover (like repetitions) but the recovery between the 300s is short and the runner will be setting off having not fully recovered.

Similar to repetitions is a  “ladder session” a variation on the same theme and has ample recover between many sets of reps but at different distances. A typical session would be 4 x 400m with 200m jog, (400m jog) then 4 x 300m with 100m jog (400m jog) then 4 x 200m with 200m jog.


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