The Physiological Process of Getting Fit.

What happens when we get fit. Well, this might apply to people taking their fitness to the next level, people getting out of lockdown or recovering from a break in training. It feels like I am becoming a bit of an expert in this due to not only being in lockdown, but I also got quite ill last year. Last year’s setback took place over five weeks. I spent two weeks not feeling well and missing most of my training sessions. I almost had that pre flu feeling. Then two days of utter misery and lots of abdominal pain that resulted in a casualty visit. From casualty I went off to ICU as my body slowly went into septic shock. I had somehow formed a cyst on my ascending colon. It was roughly the size of a fist. It doesn’t take much to imagine what it was filled with.

Cut a long story short, after 6 days I left ICU, fortunately not needing surgery. R 60 000 worth of antibiotics did the trick, or so we thought. I was discharged from hospital, however my bacterial count got worse once I was at home and off the drip. One week later back into hospital for another CAT scan and exploratory surgery, more antibiotics, this time guided by my GP, Mark Oliver. Two weeks after that, I was better and able to go for my first “run”.

My first run was a 2km run. 1 km out, 1 back. We live in a hilly suburb of Johannesburg but there  is a flat part of the route around the suburb. I decided to give a little push on that part, and so with the sounds of Chariots of Fire playing in my mind, I flew over this section at … 7 min 30 sec per km. Horror of horrors. With three months to Ironman I had my work cut out. At least I could run jog 2 of the 42 Ks that I had waiting for me.

I managed to get fit just in time for Ironman and then it was postponed. I won’t go into details of my reaction to that announcement. It wasn’t pretty.

Lockdown was a bit different in that I managed to maintain some semblance of decent training. I would run 144 loops of our garden to get an hour run in, and managed to do more strength training than normal.

So, let’s get into some exercise science as you build your fitness.

1. Homeostasis, Overload Principles and Reversibility.

I am going to breakdown three key terms with regards to fitness.

Homeostasis.
The definition for homeostasis goes as follows, “Any self-regulating process by which biological systems tend to maintain stability.” In other words, you adapt to the environment that you are put it in. If your car worked on homeostasis principles, your car engine would have reduced its size from a 1600cc to a 500cc engine by now. It would have come to the conclusion that during lockdown it is only being used three times a week for a 2km trip to the local shop. The other 1100 cubic centimetres of engine capacity are no longer needed.

If you have been spending hours on the couch, studying Neflix and getting up only to check on your fridge, you need to understand that your body has adapted to those demands. It gets rather good at what we repeatedly ask it to do.

The above description is hopefully not you. However, even the most motivated of us will have had drastic reductions in the amount of general movement done per day.

Overload Principles. 
This is what getting fit is all about. This is what I try and introduce into athletes as a coach. We overload systems in order for the body to respond and adapt. Load, rest, load rest. If you don’t push hard enough you won’t get the results you are looking for, push too hard and athletes get injured. It’s a fine balance. So, coming out of lockdown/illness/a protracted break in training gets tricky.

Reversibility Principle.
This is what happens when we take a fit individual, someone who was training for an event, and then they suddenly reduce their training. The principle is applicable to people getting ready for their first 5km run through to people preparing for an Ironman.

 

Look at the table above.
On the left is an athlete improving their fitness levels over an eight week period.
On the right is an athlete experiencing a decline in fitness due to a sudden reduction in training. The good news is that your maximal oxygen uptake tends to hold fairly well. However, two key measurements done on the vastus lateralis muscle drop dramatically. Put your left hand on your left thigh and it is most probably on your vastus lateralis muscle. Vastus lateralis is just fancy Latin for the big muscle on the side of your leg.

Definitions.
Cytochrome Oxidase Activity – very simply put, your cells’ ability to produce energy gets reduced.
SDH reduction – Succinate Dehydrogenase – again refers to your cells’ ability, in simplest terms, to turn food into energy.

So, basically, your body will come out of this able to use oxygen quite well. On a cellular level, it will not be able to generate as much energy as it was before. Let’s say you go for a run. Your lungs should cope almost as well as when you were fit, however you are going to get that heavy feeling in your muscles a lot quicker than what you used to.

Three practical points.
1. Be patient. Four weeks of consistent training will make a huge difference.
2. Maybe exercise with a carb based drink. You want to make it a bit easier for your body to transfer carbs into ATP energy.
3. Keep your heart rate low during this period. I will be giving very specific instructions to the athletes I coach as we ease out of this time period.

 

2. Bone Density – Wolff’s Law.

Wolff’s law was developed by German surgeon Julius Wolff, and states that bone is added where there is a demand for it, and removed where there is not. A tennis player, for example, will show a large difference in bone mass on his ‘playing’ arm versus the arm that is not used. The law is a great example of the “use it or lose it” concept.

Here is where we come in. If you have been sitting around for the last month your bones will have adapted to the reduced stress load. Remember the homeostasis paragraph earlier on? You will therefore become more prone to picking up a stress fracture. (I include people who have primarily been on an exercise bike during this period, in that they have in effect not been weight bearing).

Practical Steps.
1. Try before lockdown ends to introduce some impact type exercise so that your bones can toughen up again. Skipping. stairs and star jumps are all good ideas.
2. Don’t take your mileage up too quickly when you resume running. The zero to hero approach might get you in a bit or trouble.
3. Understand that Vitamin D and Omega 3 play a really important role in bone health. Make sure you are getting enough of both.
4. Read my article on RED-S or Relative Energy Deficiency in Sport. Athletes not replacing spent energy through sufficient nutrition are at risk of their bones not being able to rebuild themselves adequately, and therefore are at heightened risk for stress fractures, among other health issues.

3. Carbs, Fat and the Crossover Concept.

The less fit you are the more carbohydrate reliant you are. The more fit you are, the more you tap into your fat stores. A 70 kg person typically has 2012 KCal worth of energy stored as carbs in their body. However, our 70 kg athlete will have approx. 110 740 KCal worth of energy stored up as fat. That’s over 50 times more energy available via their fat reserves.

Let’s unpack this. At 20% of aerobic power (See the X axis) we don’t go through much carbohydrate (Dotted line) but we do burn through a lot of fat. As our athlete gets to 60% effort he/she begins to tap more into their carbs and less into fat (solid line). Where our two lines meet is known as the Crossover point (For obvious reasons). As you get fitter, the Crossover Concept states that the Crossover point moves to the right, i.e. further right on the X axis.

Do not despair if the above description sounds like Greek. All that I am trying to say is that the fitter you get, the more you feed off fat and the less you feed off carbs. Carbs, however, play a really important role as you get deeper into an endurance event. The longer you have fed on fats, the more carbs you will have in store, and the longer you will able to keep going.

So, once again, get back into training at low intensities. Take a sports drink with some carbs in it for runs or rides where you would not typically fuel. You will be able to go a bit longer if you do. Don’t despair, your body will soon remember how to tap into fats for longer at higher exercise intensities.

Please click on this link if you are interested in getting coached by myself.

I wish you all the best as you take your fitness to the next level.

Mike Roscoe.

Sources:

Exercise Physiology: Theory and Application to Fitness and Performance. S.K. Powers et al.
Exercise Physiology: Nutrition, Energy, and Human Performance. W.D. McArdie et al.