High Intensity Interval Training sessions consist of short bursts of all-out exercise, interspersed with periods of low-intensity activity or complete rest. Each high / low intensity drill generally has a fixed duration so you will probably be working with a stop watch. Sessions can last from five minutes to half and hour and sometimes even longer, depending on what you are trying to achieve.
All of the following should be accompanied by proper warm-up and cool-down periods:
Hill Repeats – Run / cycle up a steep hill as fast as you can for 1-2 minutes and then slowly cruise back down again. Repeat.
I haven’t listed them here for simplicity but some workouts also incorporate equipment such as weights, ropes and kettle bells. See the sources below for more information, references and training plans.
Exact characteristics will vary from system-to-system but here is a brief summary of common benefits associated with HIIT by prominent authors and advocates:
Whilst I agree that many of the benefits listed above can be achieved in a relatively short time period through HIIT, I don’t think it’s generally the right strategy for someone who hasn’t exercised for a while and my reasons for this are as follows:
My personal opinion is that if you haven’t been active for a while, you should find something that will give you an all-body workout and exercise at a relatively gentle, aerobic intensity to spend some time on basic conditioning before you think about introducing intervals.
You should be aiming for 2-3 hours a week if possible and during this time, you will start to re-connect with your body, improve muscle function and co-ordination and develop an aerobic base. After all, it’s the aerobic system that supplies us with energy 90% of the time so making it more efficient is a good thing (more information on aerobic development here).
Many people find that it’s easier to stay motivated if they try something that is social and / or skill based as this takes the focus away from ‘exercise for the sake of exercise alone’. Maybe yoga, pilates, dancing or swimming with friends. Things like walking and cycling are also both fantastic but make sure they are supplemented by activity that works your upper-body.
During this time, you should be working hard enough to be very aware that you are exercising but not so hard that you can’t maintain a conversation without getting out of breath (as a rule of thumb).
There are numerous factors that influence how long it will take for your body to be ready for HIIT, including age, history of illness, injury and general health. You should certainly wait until you have started to notice sustained improvements in your health, fitness and energy levels through low-intensity conditioning as described above. For some people, this will take perhaps a couple of months but for others it will be longer. It’s really important to be patient and learn to listen to your body as it starts to change.
It is generally recommended that you consult your doctor before starting HIIT. This is particularly important if you are older or have been suffering from a serious or long-term illness. You should also seek advice from a fitness professional to ensure you select a program that is right for you and to get supervision on technique to minimise the chances of injury or other problems.
Most sources recommend 2-3 sessions of HIIT per week and in my opinion, for most people it is best it if this is undertaken in fixed blocks of a limited-duration. These blocks can last from a couple of weeks to a month or more but if you go beyond that without a break, the chances of injury and over-training can increase whilst the rate at which your health and fitness improve may start to plateau. When you are in-between blocks of HIIT you can ramp-down the intensity or revert to aerobic exercise to give your body a break and ensure that you maintain a base. Again, you can find more information on aerobic development here.
Getting the exact balance right is a very individual thing and again, dependent on your goals and a whole host of other factors but it’s really important to listen to your body and look out for signs of overtraining. Remember, you won’t be able to exercise at all if you push to far and get ill or injured.
This ‘periodisation’ approach will ensure that your body will receive a constantly changing stimulus and this is more effective than doing the same thing over and over again. At the same time, it reduces the chances that you will develop an over-use injury or get bored and lose motivation.
You Are Your Own Gym by Mark Lauren is a great book on body-weight interval training that can be done at home and they also have a fantastic smart phone app.
Fast Exercise is a short, new book on HIIT that has been well received and was written Dr Michael Mosley (of the BBC).
For information on developing the aerobic system and avoiding over-training, take a look at The Big Book Of Endurance Training and Racing by Dr Phil Maffetone.
Please leave your thoughts and experiences below!
Note that the information in this post is not a substitute for a visit with a health-professional