Fitnessknowledge bankSue says...Uncategorized


HIIT vs LISS. Which is best? What are they? What are the benefits and drawbacks of each? And which you should choose to get the best results?

If you follow any fitness coach you will most likely have heard these 2 phrases; but do you know what these letters stand for? Do you know what each involves? Do you know why they are different? Do you know what the benefits of each are? Do you know the disadvantages of each? And, therefore, do you know when you should (or shouldn’t) be performing each?  Let me answer these important questions:

What do the letters stand for?

HIIT = High Intensity Interval Training

LISS = Low Intensity Steady State training

What does each involve?

HIIT consists of short periods (usually a maximum of 45 seconds) of high intensity training, interspersed with periods of recovery phases.  The length of the working and rest phases varies depending upon the goals of the individual concerned but the basic rule of thumb is 1:1 work:rest (e.g. 30 sec work, 30 sec rest or 20 sec work, 20 sec rest).  The aim is to get the heart rate as high as possible in the working phase; you are aiming for 70-90% of your maximum heart rate (MHR), allowing the heart rate to drop during the rest phase, before doing it all over again.   Given the high intensity involved, HIIT workouts usually last no longer than 15-20 minutes.

LISS includes walking, jogging, swimming etc.  Your body is working at the same level of intensity for the whole exercise time, and the heart rate should be staying fairly steady at around 60-70% of your MHR.  LISS workouts/exercise can be performed for as long as you like; anything from a 10-minute brisk walk to a 20-mile hike!

What are the benefits of each?


  • Takes little time, so great for the time-poor or those who want a quick workout
  • Pushes the heart and lungs and results in improvements to your athletic performance and an increased lactate threshold (more on this on another blog!)
  • Better retention (or even growth) of muscle mass due to the resistance training aspect of HIIT training; think jump squats, jumping lunges etc. HIIT is therefore better from a purely body composition point of view
  • Increased calorie-burn for 24-48 hours after exercising (due to EPOC – excess post-exercise oxygen consumption)
  • You’ll get that training ‘high’ as a result of endorphins being released into the body


  • Suitable for everyone, from the complete fitness novice to the fitness guru!
  • No special equipment needed – just get up and go for a walk
  • Can be done anywhere
  • A good stress-reliever
  • Takes little time to recover

What are the disadvantages of each?


  • Longer recovery times
  • Increased cortisol (the stress hormone) in the bloodstream
  • Higher risk of injury
  • Not suitable for beginners or those recovering from injury


  • Takes longer to burn the same number of calories as HIIT (plus there is no EPOC effect so overall calorie burn is reduced)
  • Does not help to build strength, power or speed
  • Can result in reduced muscle mass when in a calorie deficit

So, which should I choose?

Ultimately both forms of training have their place, and both have been shown to reduce blood pressure, improve your cardiovascular health, and increase your endurance! So, you should choose the one that suits you and your lifestyle best. Or you could mix them up to challenge yourself and give variety to your workouts!

If, however, you have a very stressful job, or you are experiencing a tough time at home right now, or you are doing more than 3 heavy weight training sessions a week I would recommend that you stick with LISS training.  This will help to reduce your stress rather than adding to it; read my blog on sleep to find out more about the importance of reducing stress on the body.

One final point…whatever you choose to do…find something you enjoy!  That way you will stick with it and at the end of the day consistency is key to achieving your goals!


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