You And Your Spleen : 01

Here at the DareToTriLife Blog we cover the in-depth issues so you you don't have to. In this short & snappy entry we think about what exactly happens when a person starts training. If you are just starting out there's a few amazing changes about to happen in your body.

You

The 1st area of change will be in your cardiovascular system. That's your heart and all the veins and capillaries which carry oxygenated blood around your body. With all the extra work you are now demanding from your muscles they need more oxygen and fuel to drive the processes which enable that extra work to take place. It's the heart that steps in 1st to help you meet that need, pumping the blood faster to grab all that extra oxygen you're breathing into your lungs.

Next up the muscles you are exercising will adapt. If they are doing more work they need more energy and that comes from the little "nuclear power plants" within your muscle cells called mitochondria. These tiny guys are amazing.  You give them lunch & they give you chemical energy. When you start training you will increase the number and size of mitochondria in your muscles. It's like trading up an engine size ... forget 1100cc : after a month of training you're on your way to be your very own 2 litre GTI.

Two mitochondria gossiping

Not only that. There's more. Your enzyme activity increases so that oxygen delivered can be processed faster and your body cleverly opens up extra blood capillaries around the working muscles to improve the delivery of oxygen even further. Of course all this improvement in delivering useful stuff to your working muscle cells is equally good at removing the waste products such as carbon dioxide. This happens automatically and it's just waiting for you to slip on the trainers and go for a run today to make it all happen.

Lets think about your heart. There are 2 aspects : the stroke volume (volume of blood pumped per beat) and the heart rate (the number of beats per minute). As you become fitter the 1st change is the stroke volume. Your heart is working more during your periods of training so it becomes stronger and it pumps more blood per beat. The immediate dividend for you is that when resting your heart is now more efficient (stronger). You need less beats to deliver the necessary oxygen and that causes the resting heart rate of fitter people to be lower.  

As you become fitter you will move your "lactate threshold". Say what ? Lactate is produced by excerizing muscles and has been thought to contribute to fatigue or muscle soreness. The idea is that the fitter you become the better at clearing lactate from your muscles and the less fatigued you are. This is now quite controversial.  Lactate itself is a fuel that is used by muscles during exercise and lactate released from the muscle is converted in the liver to glucose, which is then used as an energy source. So it helps to delay the lowering of blood glucose - which actually delays fatigue. But the bottomline is that by being fitter you shift the point when the lactate kick's in.

Finally what about your Aerobic Capacity ? What indeed. Improved cardiac strength plus all those extra bigger mitochondria and opening up more pathways to your muscles enables you to use more oxygen. More oxygen = more work is possible so you go longer faster. Your ability to process oxygen is often called VO2 Max - that is the maximum amount of oxygen you can process during an activity. As you become fitter your VO2 Max increases. We love VO2 Max. It correlates with loads of things for example your VO2 Max can indicate how fast you'd run a 10k or a marathon. But we'll come back to that another time. For now just get out there and train.

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