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Training your body to deal with lactic acid

The benefit of float intervals is that they help train your body to deal with the lactic acid that builds up during a harder effort. They are also a great way to work on your pacing.

Running fast improves running technique, economy and speed. But it also takes longer to recover from more intense training, so adding the right amount of speed work is a challenge for any triathlon program. One way to maximize the benefits of speed training is to include, within the set, some intervals designed to improve your lactate threshold. Turning what we call “repetition” intervals into “float” intervals is one way to do this. Here is an explanation of the two types of interval training.

Related: How to recover from your first (long) long run

Repetition Intervals

Traditional intervals on the track are fast and relatively short efforts that train you to run efficiently at a faster pace. Repetition intervals are high intensity with longer rest in between. Repetition intervals are designed to encourage more quality. The rest portion of the workout can either be a complete rest (standing) or an easy walk or jog to keep moving before running again. For example:

  • 6 x 400 m (run at 5 km pace) with 90 seconds rest or easy jog

Float Intervals

Float intervals are done at the same intensity as repetition intervals, but instead of resting completely, athletes go straight into a “float” recovery. The intensity and the pace of the float recovery depends on your current fitness. The goal of float intervals is to establish a rhythm within both the fast and the recovery pace. By self-determining how fast the “float” is between intervals, athletes can learn the pace at which they can recover before performing another repeat. For example:

  • 3 x 1 km that includes: 2x 400 m (run at 5 km pace) with 100 m float recovery and 2-minute rest between sets
  • This translates to 400m (5km) + 100m (float) + 400m (5kmpace) + 100 m (float )= 1 km with 2 minute rest

The benefit of float intervals is that they help train your body to deal with the lactic acid that builds up during a harder effort. They are also a great way to work on your pacing – it is common for inexperienced athletes to start faster than they should after taking a typical rest in between intervals, only to slow down by the end of the interval. This means that there’s a disconnect between being able to gauge, or feel, what your race pace should be, which is important for triathlon pacing off the bike.

How to incorporate float intervals

Float intervals are a great way to develop a feel for your race pace. To train at the appropriate rhythm, it is important to train at a pace that meshes with your current fitness for this type of set. Trying to run at a “dream pace” or “pace I ran 10 years ago in college” for float intervals won’t get you too far. Running float intervals based on “feel” is an effective way to establish good pacing habits and will help you to improve your ability to deal with lactic acid buildup during hard efforts.

Related: 5 tips to improve your 5K and 10K run times off the bike


  • 20 x 200 m with 100–200 m “float” rest or
  • 10 x 400 with 200 m of “float” rest.

Related: Two key run workouts for a 10K

The “float” can start as easy running, but as your fitness improves, you should increase the pace. The goal is to train your body to metabolize lactic acid quicker and, as a result, maintain a faster pace during the float phase of the interval. The key to success is “rolling” at a pace that maintains your rhythm and turnover as you head into the next interval. Maintaining rhythm avoids abruptly slowing down at the end of the fast part of the interval or rapidly accelerating into the hard effort after the recovery.

For full-distance athletes, float intervals at half-marathon and 10 km race pace are great for establishing what your marathon pace should be. Alternating kilometres at 10 km pace and half-marathon pace serve as excellent speed work if you’re preparing for a marathon. For beginner athletes, alternating five-minute intervals at 10 km and half-marathon race pace is another good option. Using time rather than distance is a great way to keep a group closer together, too.

Related: Four runs that will help improve your half marathon time


  • 10 km as 5 x alternating 1 km (10 km race pace) with 1 km (half-marathon race pace)
  • For athletes whose paces are not close to 5 minutes or less per km: 5 x 5 minutes at 10 km pace with 5 minutes at half-marathon pace.

If you are looking to improve your pacing, give float interval workouts a try. Endurance, economy and speed all improve immensely from this kind of run training, and you will feel more confident about the final leg of your next multisport race.