High-intensity interval training: why and how to do HIIT

Interval training workouts involve structured exercising at different intensities with recovery periods in between. High intensity is usually anaerobic exercise, while the recovery periods involve activity of lower intensity.

High-intensity interval training (HIIT) workouts exercise the cardiovascular system, which will then improve the athlete’s aerobic capacity leading them to exercise for longer and/or more intense levels.

To be faster come race day, whatever your triathlon distance, means incorporating tough sessions into your average training week. These will force your muscles to produce more power, work more economically and increase tolerance to internal chemical stresses.

This serious, go-fast mission involves endurance sessions, nutrition practice, high-intensity interval training and technical sessions.

To be your best doesn’t mean that in every session you should beast yourself. That’s not following a triathlon training plan; that’s just training by ego. Instead, follow these three, ‘fast club’ rules.

Less can be more

Experts across the field of endurance sport agree that doing just 10-20% HIIT, annually, is enough for not only elites, but age-groupers, too.

For this to work, however, the remaining 80% or so must be low-to-moderate effort (zone 1) using controlled training sessions where heart rate stays below 80% of maximum heart rate.

Stay out of the grey zone

Only a small amount of really hard work is necessary, the rest is controlled. Some sessions have no logic or proven benefit. For example, ‘just above, just below threshold’. Some coaches call this a physiological ‘grey zone’ where you’ll accumulate fatigue and minimal training benefit.

This may burn more calories than in Z1 (in a three-zone model) and provide a satisfying post-workout buzz, but there are proven, better ways to train.

Then relax

Choose the right combination of effort level, duration and recovery to achieve results not sweat.

The best high-intensity interval training sessions for triathletes

Incorporate these interval workouts to engineer more race speed.

These efforts fire up muscles via the high-powered ATP-CP energy system (adenosine triphosphate (ATP) and phosphocreatine (PC)), yet they do so for a short enough time so as not to increase lactate and breathing significantly.

Micro-burst intervals

Feel the speed but ensure you maintain form.

Swim

Up to 40 x [15sec swim @ above 1,500m pace, 15secs cruise/recovery]

Bike

10 x 6-10secs seated bike sprint surges, 2mins active recovery

Run

12 x 30m acceleration @ 5km pace, 300-400m jog recovery

Lactate accumulation intervals

Work at around 84-90% of HRmax and you’re in the threshold zone – a place where lactate produced by the muscle is just about being recycled fast enough to continue working. Embrace the lactate by controlling your breathing.

Swim

3 x 10mins @ 84-88% HRmax with approx 2mins recovery

Bike

6 x 5mins @ 88-90% HRmax with 2:30mins recovery

Run

4 x 8mins 85-90% HRmax with 2mins recovery

Threshold accommodation intervals

Also known as supra-maximal efforts, lactate-sprints and intense intervals, these sessions involve working at your maximum for around 30secs before a whopping recovery period. Get ready for a hiding or forget starting it at all.

Swim

6 x 50m maximal pace with 2-4mins recovery

Bike

5-12 x 30secs maximal sprint with 4:30mins spin

Run

6 x 200m maximal run speed with 4mins jog recovery