CardiNO – LISS vs HIIT

Cardio – the short term for cardiovascular exercise; a key element to most programmes and an area of my fitness regime which definitely gets neglected. Cardio exercise as you may have guessed, is exercise that involves the cardiovascular circulatory system (Heart, Lungs and blood vessels). Training this system allows for more efficient oxygen delivery to muscles which results in quicker recovery time (DOMS be gone!) and aids in fat burning by speeding up bodily processes i.e. metabolism. I have come to the realisation that it is time to make more efforts to incorporate more cardio based elements to my routine but of course, it is not that simple. There are many different methods of cardio training and it is important to find the right method for you and your goals. The two most popular and opposing forms at the moment appear to be HIIT and LISS.

LISS, as well as being the name some family members call me, stands for Low Intensity Steady State or Low Impact Steady State. 

This method of training uses the aerobic energy system (blog post on energy systems coming soon). Exercises are endured for longer periods of time -usually 30 to 50 minutes. The Low Intensity or Low Impact part means that exercise is done at a more comfortable level, usually aiming to be working at 40% – 60% of maximum heart rate; you will know if you are working within this range as you can still hold a conversation . The Steady State part means that your pace/speed/heart rate should not alter much, if at all, throughout the duration of the movements. 

LISS does support fat burning as it uses fat as its primary source of energy however, it is a slow process when compared to other forms of fat burning cardio.

LISS would be best suited to those who are concerned with training stamina and endurance such as long distance runners.

HIIT stands for High Intensity Interval Training and is pretty much the exact opposite of LISS. 

The High Intensity element involves working at 70%-95% of your maximum heart rate and this uses the anaerobic energy system – you will know when you get to this point as breathing will become uncomfortable. The Interval Training element is as you would imagine, training for a short period of time followed immediately with a period of lower intensity exercise or rest i.e. 15 sec sprint followed by 15 sec jog or rest. 

HIIT sessions tend to be short in length. The primary energy source for HIIT is carbohydrates with a secondary source being fat. 

HIIT would be the more appropriate form of training for those who care to increase speed, agility and reduce body fat and perhaps incorporate some strength elements to their cardio sessions i.e. Boxing training and short distance sprint training.

Many research results indicate that participants of HIIT showed the biggest reductions in body fat percentage as well as prolonged maintenance of the same when compared to results of LISS participants. This highlights that from a fat burning perspective, HITT is hands down the winning training method. This is largely due to EPOC (Excess Post Exercise Oxygen Consumption) which stimulates the metabolism to continue burning calories at a high rate for the 24 period post session. 

This EPOC phase is fuelled by fat stores and thus making it a favoured form of cardio in the body building world particularly during a ‘cut’ as muscle mass (GAINZ) are preserved whilst dropping weight.

Often we hear that people don’t do any form of working out due to time constraints. Published research results have suggested that doing 15 minutes of HIIT twice per week is the equivalent to doing 1 hour of LISS (and in some cases more beneficial so a better use of time). Additionally, with HIIT we are able to incorporate some strength building exercises and with the changes in hormone profile which accompany this (i.e. increased endorphins and Human Growth Hormone) the benefits of HIIT can go beyond just weight loss goals.

 

 

 

 

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