VO2 max and the anaerobic threshold: finding a runner’s sweet spot – South China Morning Post

There’s a point in some runs, be it a few minutes in or after 20 kilometres when you push your body and it appears to hit its groove. It has numerous names, but ask anyone who pounds the pavement and they will know what you’re talking about: the sweet spot, cruise control, hitting your stride, getting into the zone.

While listening to the body is important while training for the 2020 Standard Chartered Hong Kong Marathon like I am, it’s always interesting to dive into the science of what is going on inside the body. Last month while in Dubai covering a CrossFit Sanctional, I headed to a state-of-the-art sports and human performance clinic – Emirates SportsMed, which has tested and worked with athletes such as Frank Lampard, Olympic sprinter James Ellington and CrossFit star Brent Fikowski.

Dr Dejan Jovanovic, a sports and physical medicine specialist with the clinic, and his team were keen to test someone like myself, a 37-year-old runner you could place in the hobbyist category, but who is probably in peak physical condition. I gave up alcohol in May and have since dived head-first to see just how far I can push myself in nine solid months of training – diet, exercise, mental preparations have all been full on.

The whole process in Dubai falls under what is called Cardio Pulmonary Exercise Testing (CPET) where finding the body’s limitations and threshold is the goal – or to put it more poetically, my own personal “sweet spot”. While the mental side of running is fluid and qualitative as one’s resolve during a long run is tough to analyse statistically, the body is a different story. In today’s day, as they say: we have the power.

The goal going in was simple: use the testing with Jovanovic to find out what is the maximum speed I can possibly run without crossing over my own anaerobic threshold – the point in which my body’s metabolism must switch from an aerobic state. The best way to describe this is when the body is in a aerobic state, it’s burning carbohydrates and fats in the presence of oxygen, producing carbon dioxide and water as by-products (sweating).

Once the body goes into an anaerobic state, the body starts burning stored sugars to keep up with the extended energy, and lactic acid is produced faster than it can be metabolised, which leads to fatigue and eventually the dreaded “runner’s wall”. The goal of any good long-distance athlete is finding a sweet spot right below the anaerobic threshold, where the body can sustain long periods of exercise without going into crisis mode.

The first test at the clinic was to check my heart’s rhythm and electrical activity, which required a quick chest shave and monitors placed on my skin. My RR (time between beats) was normal and in fact I have something called “sinus bradycardia” which means my resting heart rate is slightly lower than average for a person of my age, which is common in athletic people and nothing to worry about.

“This means that your heart has larger pumping reserves due to consistent training,” said Jovanovic. “And it has become more efficient – pumping the same volume of blood needed for full body with less frequency, due to stronger muscles and larger volume ejected in every pumping cycle.” I also showed no signs of any “silent risk” when it comes to electrical conductivity abnormalities, a good thing concerning how deadly heart disease is heading into middle age for anyone.

Next I got back in the BOD-POD, (I first got tested via Joint Dynamics in September, clocking in at 10.7). This time around, more than four months later, that had been whittled down to 6.5 per cent, which puts me at the high end of the elite category, given I am 82 kilograms and 188 centimetres tall with a Body Mass Index of 23.2. The fact that I was able to shave off an additional four per cent or so through hard training and cleaning up my diet even more so (despite the occasional Snickers bar at work) is a testament to the fact that if you run a lot (clocking 70-100 kilometres a week is a regular occurrence for me), fat has nowhere to hide. Jovanovic said a big part of this is the fat I can’t see.

“You were able to trim significant amounts of your inner fat deposits,” he said. “Visceral fat, around the inner organs and inner abdomen, and I think this was reason for very low levels of detected fat.”

The first time I did my VO2 max was also in September at Joint Dynamics where I clocked in at 48.8 while I was still 36 – which required me getting on a treadmill for about 20 minutes and running until fatigued at an ever increasing speed and gradient. What this VO2 number means is my body’s maximal oxygen consumption level, or as Jovanovic put it, a “real-time” test of cardiovascular fitness and metabolic efficiency of the body. “What is the overall body capacity to absorb oxygen, pump blood and perform intensive physical work simultaneously, calculating the combined effort of lungs, hearth and full body muscles.”

I spent just over 20 minutes on the treadmill this time, and my VO2 max clocked in at 47.1, but with the added markers and testing we were able to go much deeper when it comes to medical analysis. While I was running, a nurse at the clinic tested my blood seven times to see where my lactic acid levels were, which is a good indicator of my “dominant metabolic systems during applied activity”.

Looking at the graph (pictured above) you can see as I went up, my VO2 max stayed on a relatively normal upswing. It wasn’t until after I hit 14 kilometres an hour running speed on the treadmill that I hit my anaerobic threshold (the green triangle), which is somewhere between 14 and 15 kilometres an hour. For a long distance runner like myself, this information is invaluable given I can take this knowledge and apply it to my training regime.

Thus, the golden number becomes quite clear. If I were to run a full marathon (42.195km) at 14 kms an hour, I would clock in exactly at three hours and 50 seconds. Of course a number of factors come into play: weather, how I feel that day, and a host of other variables, but scientifically speaking, my body should be able to handle a low three hour marathon time if it all comes together on February 9th.

Jovanovic was also able to give me another valuable number, my ideal heart rate, or as he called it, my “upper aerobic sweet spot”, which is somewhere between 145-155 beats per minute. Together with my ideal running speed, I now know what level my body can get to without crashing into the dreaded runner’s wall. Knowing this also helps the mental side of my training, as if you know what your body is capable of, asking the mind to come along for the ride isn’t nearly as hard of an ask any more.