Energy Systems II (Glycolytic System)

Last week I looked at the ATP-PCr system and how it worked (briefly) the time it was in use and ways to influence its effectiveness. Quite a few people did say that they weren’t concerned about training this specific energy system due to its short time in use – and while I could see their point of view, others highlighted that this system could be the difference between a dominant position and a poor position i.e. effective powerful take down/throw etc, etc

What I may not have made more clear is that ATP is required in all stages – in fact no ATP no energy (this is probably the simplest way I can put it).

Next up is the Glycolytic System aka Glycolysis.

Last week it was explained that the ATP-PCr system would last up to a maximum of 15s and once expended will be replaced with the Glycolytic system. Remember the ATP-PCr is the simplest of the energy systems – this is not so simple and the process is more complex. This may baffle some and will be ‘sucking eggs’ for others!

Glycolytic/Glycolysis – Is the breakdown of glucose through a sequence of glycolytic enzymes. It is stated and accepted that glucose accounts for about 99% of all sugars in circulation. For the sake of clarity – all blood glucose comes from the digestion of CHO (carbohydrates) and the breakdown of liver glycogen (up to 500g is stored at any given time).

The process of glycogen being synthesized from glucose is called glycogenesis. Glycogen is stored in the liver and muscle until needed. Once needed, the breakdown begins with glycogen being broken down to glucose-1-phosphate. This enters the glycolysis pathway (glycogenolysis). Before glucose or glycogen can generate energy (ATP) it needs to be converted to glucose-6-phosphate. To obtain glucose-6-phosphate the body requires ATP (1 molecule). Below is a picture of the process in its entirety. Glycolysis technically begins once glucose-6-phosphate is formed.

Fig 1.1

As seen above between 10 and 12 enzymatic reactions are needed for the breakdown of glycogen to Pyruvic acid. This process offers a net gain of 3 moles ATP for each 1 mole of glycogen broken down. If glucose is used instead of glycogen the net gain is 2 moles of ATP due to 1 mole of ATP being used to convert glucose to glucose-6-phosphate.

At the end of the above process Fig 1.1. you are left with pyruvic acid/pyruvate. This has two options - in can convert to Acetyl CoA (this is the start point of the TCA Cycle - will be explained in Energy Systems III) or it converts to lactic acid/lactate. The option chosen by the body is determined by the presence of oxygen - limited/no oxygen lactic acid/lactate - oxygen presence Acetyl CoA.

As were talking about this specific energy system (anaerobic) the lack of oxygen results in the pyruvic acid being converted directly to lactic acid. Lactic acid will then release Hydrogen ions (H+) and the rest of the compound will join with sodium ions (NA+) or potassium ions (K+) to form salt called lactate. Anaerobic glycolysis will produce lactic acid - this is however quickly dissociated and lactate is produced/formed.

This process will either stop (when you stop), fatigue (Muscle acidosis) or will transfer to the Oxidative System (Energy Systems III).

Lactic acid also have another effect on the muscle and I will explain as briefly as I can. Resting mmol/kg of lactic acid is 1 mmol/kg - this however can increase to up to 25 mmol/kg. With the increase in mmol/kg free H+ will diffuse from the muscle. Mechanisms are in place to buffer the H+ but during intense exercise the capacity to neutralize H+ can become saturated. With the increase in H+ we see a the reduction of calcium being released from sarcoplasmic reticulum or by impairing myosin ATPase activity (stopping myosin from detaching from actin) which thereby slows the contraction/relaxation process and could gives you Muscle acidosis = pain.

I needed to mention the above as it is an important part of the process and an end result if the system runs to exhaustion prior to entering the oxidative system. Mentioned in the last process is myosin, actin, calcium - as I will run out of time and space watch this Sliding Filament Theory

I hope your holding up with me.... The ATP-PCr and Glycolytic cannot provide energy needs greater than roughly 2 minutes.

Training the Glycolytic system has been widely studied and considered vital in many sports/events. Training this system has predominantely been broken down into two sections. Increasing the 15-30s (fast glycosis) and up to 3 minutes (fast glycosis and oxidative).

Fast Glycosis:

75-90% maximum power for 15 - 30s with a rest ratio of 1:3 to 1:5

Fast Glycosis and Oxidative

30-75% maximum power for 60s - 180s with a rest ratio of 1:3 to 1:4

I appreciate this was a big one - and the next one I'm afraid will be even greater. I try to be as simple as possible but I wish to remain true to what this blog is about, BJJ and Science relating to BJJ. The energy systems are vital to all sports and a basic understanding of them and how to train them is only a good thing.

Go Roll, oossss

Reference List:

Beachle, T. R., and Earle, R. W. (2008), Essentials of Strength training and Conditioning, Leeds: Human Kinetics.

Sewell, D., Watkins, P., and Griffin, M. (2005), Sport and Exercise Science, An Introduction, Oxon: Bookpoint Ltd.

Willmore, J. H., Costill, D. L., and Kenney, W. L. (2008), Physiology of Sport and Exercise, Leeds: Human Kinetics.