High-intensity primer

High-intensity exercise will give you results in the shortest time possible. But what kind of HIIT workout is best for you? Cat Woods explains.

Everyone has a goal for their training. It might be very precise: you’re running a marathon and you need to be capable of achieving a certain speed in a certain time before the date of the race. For others, it’s less defined but no less important: rehabilitating an injury, building muscle definition, increased energy and endurance for a demanding work life, or losing weight and increasing cardio fitness on recommendation from health professionals.

Regardless of your goal, high-intensity interval training (HIIT) is a method of training that can be adapted to your level of fitness, using equipment or bodyweight exercises. It has solid research to back up its claims about health and fitness gains, so before you dismiss it as a fad, discover how it will work for you.

What is HIIT?

HIIT requires you to train at a neutral or base level with short bursts of intense, heart rate-boosting, muscle-burning activity at regular intervals. These short bursts of high-intensity exercise are performed at your maximum endurance level, so it’ll be different for everyone. These endurance bursts are followed by a recovery phase before the next burst.

Why should I train this way?

HIIT burns fat, increases endurance and cardio fitness, and takes up half the time of the average workout — plus it reverses signs of ageing on a mitochondrial level.

Studies have shown that, compared to regular gym workouts (moderate challenge and no maximum effort), people including just two HIIT sessions a week over eight weeks reduced body fat, improved flexibility and increased their cardiorespiratory fitness. Participants doing HIIT sessions were also shown to build their muscle and strength at a cellular level.

Can it work at beginner and advanced levels?

The challenge of HIIT is to find your maximum endurance level and aim to work with perfect technique the whole time, no matter your fitness or ability.

A HIIT workout might look like a 30-minute treadmill session where you briskly warm up for 5 minutes, work into a steady, stable pace between 8-11km/h for 5 minutes, then sprint as fast as you can for 1 minute (at 16-20km/h) before returning to the steady pace and repeating the cycle.

Most cycling classes operate with the HIIT method — cycling at full speed for short bursts followed by a steady recovery period.

Beginners may want to start with shorter interval bursts and longer recovery phases as they get used to transitioning between levels of endurance and maximum effort.

Prepare properly

For many of us, the gym is a respite from our work lives, which are largely sedentary. Going from sitting at a desk for hours into a training session requires adequate preparation, especially for high intensity.

Eat a carb-based snack an hour or so before your session to give you energy. Stay hydrated throughout the day and dedicate time to warming up and foam rolling or dynamic stretching. Begin at a moderate pace and assess your energy levels.

Many athletes who engage in regular HIIT sessions as part of their regimen have a team of health professionals to help them. Without this sort of support, you need to take ownership of your own recovery.

Allow for one or two rest days between sessions, maintain a wholefood-rich diet and modify any activities that aggravate injuries or soreness.

The rise in popularity of HIIT has inevitably led to a rise in workout injuries and concern from medical and sports professionals about the safety and suitability of this style of training because technique, posture, safety and form are often sacrificed for the sake of a fast and full-bore workout.

This doesn’t mean that HIIT isn’t for you. Be realistic about how you train and take a low-impact option if you feel you’re not up to the intensity of a full HIIT workout, especially if you have pre-existing injuries.

The alternative

High-intensity low-impact training (HILIT) removes jumping, kicking, lunging and leaping from your training session, so there’s less risk of joint damage. It requires you to keep both feet on the ground, which means a training session could include lots of plank holds, mountain climbers, squats or the use of TRX cables, dumbbells and balls. The beauty of HILIT is that it preserves the joints while still achieving a solid calorie burn.

Ultimately, the main thing to consider when you’re doing HIIT is to train smart and sustainably. If you go too hard, too fast and too often, your body won’t have sufficient time to reap the benefits of your training and your immune system will suffer and become more vulnerable due to fatigue and stress.

Your body also won’t burn calories as efficiently and effectively when it’s under stress and fighting illness.

Prevent HIIT from hurting

  1. Make sure your health professional gives you the all-clear to train at a high intensity.
  2. Always favour good form over speed.
  3. Talk to your personal trainer or class instructor before you start about any concerns (pre-existing injuries, weaknesses or conditions).
  4. Start at a moderate pace if you’re new to HIIT.
  5. Any pain in the joints is a sign to back off and reassess your form and technique.
  6. Make sure to have rest days in between training ‒ ideally, three HIIT sessions a week.
  7. Make modifications to any activities that feel risky or unsuitable.
  8. Always warm up before and cool down after a HIIT session.
  9. Go easy on days where you don’t feel energised enough to complete your HIIT sessions so that you’re ready for the next one.
  10. Avoid boredom by trying new activities, working out with others or taking it outdoors.

High-intensity classes

Fitness First runs RPM classes, HIIT Blast and Freestyle Group Training sessions daily. If you’re new to exercise, it’s recommended that you book with a personal trainer to get a customised HIIT workout, expert guidance and support on technique and form.