Benefits of Interval Training, importance of Lactic Acid

Interval Training – Why do it?

I see a lot of women in the gym spending hours on end jogging tediously, all expecting the same results – to burn fat quickly. However, from research and my own training experiences I have found that this is the most ineffective way to train if your training goal is to burn fat. The moderate pace of the exercise does not allow the body to exert enough energy to reach the fat burning zone, therefore women spend hours on end performing an exercise which is not effective for their training goals.

So what difference does interval training make, I hear you ask…

Interval training works on the premise of fixed periods of rest and work, it is important to remember that the periods of rest are referred to as “active rest”, which has been shown to reduce the muscle lactate levels. Okay, so your probably thinking “lactate levels what are these”.

So here is the science behind it…

The lactic acid system is capable of releasing energy to resynthesise ATP without the involvement of oxygen and is called anaerobic glycolysis. Glycolysis is breakdown of carbohydrates which results in the formation of pyruvic acid and hydronium ions (H+). The pyruvic acid molecules undergo oxidation in the mitochondrion and the Krebs cycle begins. This results in the build up of H+ which makes the muscle cells acidic, therefore interfering with their operation so carrier molecules, called nicotinamide adenine dinucleotide (NAD+), remove the H+. The NAD+ is reduced to NADH that deposit the H+ at the electron transport gate (ETC) in the mitrochondria to be combined with oxygen to form water (H2O).

If there is insufficient oxygen then NADH cannot release the H+ and they build up in the cell. To prevent the rise in acidity pyruvic acid accepts H+ forming lactic acid that then dissociates into lactate and H+. Some of the lactate diffuses into the blood stream and takes some H+ with it as a way of reducing the H+ concentration in the muscle cell. The normal pH of the muscle cell is 7.1 but if the build up of H+ continues and pH is reduced to around 6.5 then muscle contraction may be impaired and the low pH will stimulate the free nerve endings in the muscle resulting in the perception of pain – this is what athletes describe as the “burn” and therefore refer to as the build-up of lactic acid, by also ensuring that you have an active rest it allows the blood to pump a sufficient supply of oxygen to the muscles at a quick enough pace, before you go through enough bout of high intensity work.

It is important to note that lactic acid is not a bad acid, it is part of the energy systems protocol to the release of ATP. So in terms of lactic acid and interval training, the training will not get rid of the lactic acid as it is a natural occurrence but it will increase the bodies tolerance as the training will them to work through “the burn” and enough training of high intensity sprints will prolong the period of running until the lactic acid kicks in.

What is interval training?

Interval training can supercharge your fitness, boost your metabolism, burn off that extra fat and start reaching those goals that you have set yourself. High Intensity Interval Training (HIIT) is about mixing high intensity bursts of exercise with moderate intensity recovery periods, it can be brutal but has incredible advantages.

It works by ensuring the athletes heart rate is increased to 75-90% of their maximum heart rate (220-age). By performing short intervals of high intensity work you push your body to its anaerobic threshold limits, thus increasing the energy exertion which allows the body to work in the fat burning zone.

Your anaerobic threshold can be described as a point where the muscle gets fatigued (feeling heavy, burning sensation), this is the build of lactic acid (remember not a bad thing). Anaerobic activity is where the body is exercising at such a rate that it cannot supply enough oxygen to the muscles fast enough, therefore essentially working without oxygen. The muscle still manages to receive oxygen just not enough to meet the demands of the exercise. The point at which you reach this stage of muscle fatigue can be delayed with interval training, the exercise has to be at a high enough intensity to ensure you stay at your anaerobic threshold for a longer period of time.

So far we have covered the science behind interval training, the benefits of interval training to the delayed onset of lactic acid and active recover.

Fat Loss?

By pushing your body hard you can increase your metabolism (how fast your body burns fast), the benefits of this type of training doesn’t only come within your workout but also afterwards as your body will continue to burn calories after the activity.

Several studies have shown that interval training is a very effective way of burning fat, even more so than the traditional endurance run. A study in the University of Alabama compared the traditional training against interval training and results showed that energy expenditure was 160 calories more in the high intensity candidates; in fact the amount of calories burned in the endurance exercise was 3 times lower.

Due to the body working at such a fast rate, the work keeps on going after exercise so the fat burning process can continue for up to 24 hours after the activity is completed, this is why it is also important to eat as soon as possible after the activity, as the food is going to be broken down a lot quicker. Protein shakes and meat are a very good supplement due to their ability to repair and replenish muscles.

So what does a typical session look like:

Beginner

5 minute warm up

Then 5 sets of….

2 minute jog

30 second sprint

Advanced

3 minute warm up

Then 5 sets of….

1 minute jog

1 minute sprint

2 minute hill climb

30 second sprint

These are just a few examples of interval training, programs will alter with each individual, depending on fitness, goals and the type of exercise being performed.