Hello and welcome to the Competitive Edge Sport Science blog. This blog will serve two main purposes:
1) to document my training from start (here) to a half marathon in 7 weeks, then onto the Auckland Marathon in October, and…
2) to highlight new research and techniques or common myths or inaccuracies relating to Sport & Exercise Science and its application in the real world.
So lets start with the training for the half marathon, it starts with an incremental Blood Lactate test… This is mostly to get baseline measurements as in my currently untrained state the results obtained may be less than perfect – this is because an athletes Blood Lactate profile at any given point in time, and at any given workload is dependant on a number of different variables, not just oxygen consumption/availability as previously (and sometimes incorrectly still is) thought.
So what do we notice first about this graph?
Well, the first thing I notice is the ‘bump’ at around 8kph. So what caused it? This occurred at the same time as I switched from walking to running, and the fact that it didn’t increase (and even decreased) in the next few stages of the test, tell us that it is not a purely physiological reaction to the increase in workload/speed. The key here is the change in biomechanics that occurred when my gait when from walking to running, and the fact that this was a baseline test when I have not been running for a long time. The result of this is that for me, running had become almost a novel movement – I have obviously been walking every day ever since I could walk, so I was fine with that, however both kinematics and kinetics change immediately the second we move from a walking to a running gait.
So why is all this important? It’s because the brain sends motor programs to the muscles for every single movement or pattern of movements we make – even typing this my brain is sending out hundreds of different motor programs hundredths of a second apart to make my fingers hit the keys. I use a computer and a keyboard everyday, so am quite fast at typing – but ask someone who hardly ever uses a keyboard to type the same paragraph and it would take them a lot longer – and it’s similar with running or any other new sporting movement.
To put it simply, my brain and body was not practised in running, so the small increase in intensity (1kph) did not cause all of the increase in blood lactate at the 8kph stage, but part of it was the result of a change in gait. More specifically, we can ascertain that this change caused a more novel, less practised motor program to be used, and subsequently a large shift in the number of fast twitch (Type II) muscle fibres to be used. These muscle fibres use glycogen as an energy source and contain fewer mitochondria, and thus lead to an excess of lactate produced over the amount consumed in the working muscles. This gave a noticeable start to the lactate shuttle in my body, and the absence of an increase in lactate levels in the next few stages of the test highlight the fact that although this shuttle had started and a large amount of lactate was being produced, other muscles that were not working at such a high intensity were able to use it as a source of fuel between 8 – 10 kph.
In this blood lactate test I inadvertently highlighted 2 problems with previous thinking regarding lactate/lactic acid and it’s role in the body during exercise. The first is that it’s a waste product, produced when intensity increases due to a lack of oxygen available t0 the muscle. If this was the case, then why would a higher intensity (10kph) produce a smaller amount of waste than a lower (8kph) one? The second is that this ‘waste product’ is only produced when there is this lack of oxygen (an oxygen independent process is different to one that happens only when oxygen is lacking), again, if this were the case how come more oxygen was suddenly found/made available at both 9kph and 10kph?
The reality is that blood lactate levels are not governed by a single aspect (eg a lack of oxygen), and are very much a result of many independent processes occurring simultaneously and linking in with the bodies energy metabolism as a whole. For a more detailed look at this take a look at our Blood Lactate pages.