This is a topic that I tip toe around with great caution because there is a fine line between getting the most out of yourself and over-training. Over-training can come in many forms, but the topic of this article is going to focus around high intensity (HIIT) workouts and getting your nutrition (recovery) right.
Extremely popular within modern day society, especially with young females, HIIT training is an effective way to burn energy and reduce body fat. Losing any body mass tells us that the body is in a catabolic state, it is breaking down compounds within the body and in this case it is for energy. With this in mind, let’s take a look at the effect of HIIT workouts on hormone concentrations and their consequential effect on catabolism.
Insulin (anabolic): decreases as sympathetic activity limits pancreas activity
Glucagon (catabolic): increases as blood glucose levels fall
Adrenaline (catabolic): increases as body temperature rises and dehydration occurs
Cortisol (catabolic): increases throughout strenuous exercise
All of these hormonal changes occur for good reason. They are mechanisms for fuelling muscle contraction. Glucagon, adrenaline and cortisol all stimulate glycogen breakdown and/or lipolysis (fat breakdown). At high intensity (greater than 75%) muscle glycogen is the main fuel source for muscular contractions and its breakdown actually disrupts the cells ability to oxidise (burn) fatty acids. What that means is that high intensity exercise does not necessarily increase fat breakdown, contrary to popular belief. Though it does substantially decrease muscle and liver glycogen stores (especially in the general population).
Now in terms of performance, fast depletion of glycogen stores is detrimental. In straightforward language, a fast reduction in glycogen reduces the time a person can spend working at high capacity and consequently limits the overall calories they can burn (the backbone of the HIIT fat-burning theory). To make matters worse, unless adequate nutrition is obtained, glycogen levels will not return to capacity between sessions. Think of it as a water-tank that empties during exercise and needs to be topped up through carbohydrate intake.
So what happens if someone is following a low carbohydrate diet and putting their muscles through a HIIT session 5 days a week?
They leave themselves extremely depleted, incapable of increasing performance, limit recovery and increase their risk of injury (fatigue induced, muscle breakdown).
Now what can we do to capitalise on the positives of HIIT training and make it a safer, more effective training method.
- Always eat before you train. You need to ensure your body is provided with energy after a long fast. You may burn more fat by not eating, though you are creating more negatives than positives. You will fatigue much faster, not only physically, but mentally.
- Include a carbohydrate source during your workout. My go to supplement is Gatorade powder. The high levels of glucose are easily utilised by our body and ALL glucose taken up during exercise is used immediately. Glucose uptake will also reduce your perception of fatigue and reduce changes in insulin, adrenalin, glucagon and cortisol levels (increasing endurance).
- Take BCAA’s during your workout to reduce the level of muscle breakdown that occurs during exercise, through stimulation of the MTORC1 complex.
- Include a fast absorbing protein and a glucose source to instigate recovery post-workout. Our body needs to be in a positive protein balance to promote muscular growth and repair and glucose is required to replace lost glycogen.
- Allow your body to recover. Your body needs to sleep; it needs to relax. The best way to start the recovery process is to use diaphragm breathing post-workout to reduce the heart rate and stimulate parasympathetic processes. Getting a good night’s rest will also go along way to ensuring your body keeps up with the demands of HIIT training.
- Drink plenty of water! Compounds produced during exercise need to be cleared from the body, muscles need to be rehydrated and adrenalin levels need to fall for recovery to occur.
HIIT is a great weapon for getting in shape, though I don’t believe it should be used as your only weapon. Mix up your training! Incorporate some strength training, increasing your overall muscle mass is a highly effective way to increase your basal metabolic rate. A greater muscle mass will become your greatest weapon in depleting body fat and keeping it away. Standard steady state cardio is also a great way to burn some calories without sending your body into overdrive. Adding 20 minutes of jogging or a fast-paced walk everyday will go along way to improving heart health and depleting body fat.
If you insist on HIIT and HIIT only then make sure you separate the muscle groups used during neighbouring HIIT sessions. An example of this would be training with leg dominant exercises on a Monday and upper body exercises on a Tuesday. This will ensure that your muscle groups are getting sound recovery time. It is important to always listen to your body and make sure that if you are feeling sore, unmotivated and low on energy, take a break! It is okay to rest; in fact, it is incredibly important to rest.