The truth about sports, nutrition and pain!

The principle of specificity

This principle refers to the effect that exercise training is specific to the muscles involved in that activity, the fiber types recruited, the principal energy system involved (Aerobic versus Anaerobic), the velocity of contraction, and the type of muscle. In other words, if I want to get stronger legs then I should train my legs and not my arms. Or, if I want to run faster then I should train sprints and not go out for long slow runs. This may seem an obvious thing to most people but when you see people train you realize that many don’t understand this concept. Let me explain.

There are three basic energy systems in the body:

  1.  Ultra Short-term Performance (10 seconds or less) – 60 meter race: most of the energy comes from the ATP-PCr and the glycolytic systems. Meaning, if you wanted to get better you would have to train those two systems.
  2. Short-term Performance (10-180 seconds) – 200-800 meter race: 70% of the energy comes from the Anaerobic systems but, as you get close to the 180 seconds, 60% of the energy would come out of the Aerobic system. So here you would have to train both systems but still put more emphasis on the Anaerobic.
  3. Moderate Length Performance (3-20 minutes) – 800 meter to 10km race: 60% of the energy would come out of the Aerobic system in a 3 minute maximal effort but, as we get close to the 20 minute mark, 90% of the energy would come out of the Aerobic system. So here you would train in a way that improves both system but put more emphasis on the Aerobic system.

So, imagine I’m a golfer and I want to improve my tee shot. That movement lasts a second or less, meaning I am working Anaerobic, so when I go to the gym I would do explosive exercises that don’t last too long. Let’s say now I’m a boxer, rounds last 3 minutes, I know that the first minutes I will work Anaerobically but as I get closer to the 3 minute mark 60% of the energy comes Aerobically, so here I would make sure to work both systems almost equally but still putting more emphasis on the Anaerobic part

What you have to do now is figure out what system your sport uses and try to improve it.

Hope you enjoyed

We already know what Vo2 Max is, why it is important to train it and at what intensities we should train to improve it. Now all we need to figure out is how to calculate those percentages to know  if we are training at the right intensities.

Let’s not forget that training intensities between 40-89%Vo2Max can improve the aerobic capacity in normal people. This means that people who are not in such good shape can train at 40 %  of Vo2Max, or even lower, and already see improvements, while people who are in better shape will have to train at higher intensities. Remember that two of the ways to improve VO2Max are by:

High Intensity Interval Training ( 80-100 % Vo2Max)- Only people who are well fit should train at those percentages.

Long Slow Distance Exercise ( 50-65% Vo2Max)- The run should usually last longer than 30 minutes.

Ok, so now the moment we have all been waiting for, how to calculate the intensity of Vo2Max you are working at. So, we do this through a method called the KARVONEN METHOD. It works because it is based on the linear relationship between hear rate and Vo2 with increasing work.

The steps you have to do are the following:

  1. Calculate your Heart Rate Max ( 220 minus your age)-This formula is not exact and the potential error with the standard deviation can be +-11 beats per minute.
  2. Calculate your  resting HR- It is usually better to do it in the morning
  3. Calculate your Heart Rate Reserve (HRR)- This equals Heart Max- Heart Rate Rest.
  4. Target Heart Rate (THR)- This is the heart rate we want to work out.

Remember that there is a linear relationship between heart rate and Vo2 with increasing work. That is why this formula works. So let us say that I want to work at 80% of Heart Rate Reserve the formula would be as follows..

THR= HRrest +0.80 ( Heart Rate Reserve)

I will use myself to put things more clearly. I am 34 years old, my heart rate at rest is 58 and I want to train at 80% of Vo2 Max.

  • Heart Rate Max:220 -34= 186
  • Resting Hear Rate: 58
  • Heart Rate Reserve: 186-58= 128
  •  THR= 58+0.80 (128)  and my Target Heart Rate would be 160.4, meaning that if I wanted to work at 80% percent of my VO2Max my heart rate would have to be at 160 beats per minute

I know it seems a little bit complicated but once you get the trick of it it will be quite easy and your training’s will be much more effective!!

Try it out and let me know if it works. Until next time




In the last blog I talked about what Vo2Max is and why it’s important to train it. In this blog I will talk about how to improve it.

Remember that having a higher VO2 Max is an advantage: it means that your body can take in more oxygen and deliver it to your muscles, enabling you to run faster for a given effort.So any person who runs races should try to improve it. In addition, people with a low VO2Max increase the risk of death from all causes (1) !!There are various ways to improve VO2Max but I will give the two most known and those are:

1.High Intensity Interval training– Here you would do series of at least 50-60 seconds of high intensity.  The work- rest ratio would be = to 1:1, 1:2, or 1:3. The work- rest ratio 1:1 means that if you work, for example, 60 seconds you would also rest 60 seconds. The work rest ratio 1:2 means that you rest twice the time of work, so, if I worked 60 seconds I would rest 120 seconds and so on.  For athletes who are not highly trained, a work- rest ratio of 1:3, or 1:2 may be preferable. As a general rule for young athletes, the heart rate should drop to approximately 120-130 beats (2). The  exercise should be done at 80-100% of VO2Max to improve aerobic power.
2. Long Slow Distance Exercise– Low intensity exercise where you should be working at around 50-65% of  VO2Max. The duration is generally greater in length than the competition you would be doing.

  • It is believed that high intensity intervals are more effective in improving VO2Max than low intensity intervals (3,4). Meaning that even  running intervals of 30 seconds or less at full intensity could improve VO2Max.

Now, you are probably thinking that this is nice but how in the world do I calculate my VO2Max to know what percentage I am working at. This is quite easy…..but I will talk about that in my next blog. See you then.





  1. Kodama S, Saito K, Tanaka S, Mai M, Yachi Ym Asumi M, et al. Cardiorespiratory fitness as a quantitative predictor of all cause mortality and cardiovascular events in healthy men and women. Journal of the American Medical Association 301:2024-2035, 2009.
  2. Astrqnd P, and Rodahl K, Text bookd of Work Physiology. New York: McGraw-Hill,1986.
  3. Hicson RC, Bomze HA, and Holloszy JO. Linear increase in aerobic power induced by a strenous program of endurance exercise. J Appl Physiol 42: 372-376, 1977.
  4. Hickson RC, Hagberg JM, Ehsani AA. Time course of the adaptive responses of aerobic power and heart rate to training. Med Sci Sports Exerc 13:17-20

What is Vo2Max?

Some people have probably heard of this, some may have not. For those that haven’t I will give a quick explanation of what it is and why is so important.

Vo2Max,  means the maximal capacity of the body to transport and use oxygen during dynamic exercise using large muscle groups. In other words, Vo2max is the maximum way to produce energy aerobically while you run, bike,swim, etc.Remember from my last blog (click here), that we can produce energy 2 ways: Aerobic and Anaerobic.

  1. The anaerobic system is the fastest way the body has to produce energy, the bad thing about it is that we cannot maintain this system during long periods. This system is used especially during short-intense exercise, like for example, a 100 meter race.
  2. The aerobic system produces energy at a lower pace but it can be maintained  for much longer periods. For example, when we run a marathon most of the energy will come from that system.

Vo2Max is measured in milliliters of oxygen per minute per kilogram of body weight (ml/min/kg) and the highest Vo2max recorded was a Norwegian cross-country skier with 94ml*kg*min!!

Why is it important to have a high Vo2Max?  Because all else being equal, a higher VO2 max is an advantage: it means that your body can take in more oxygen and deliver it to your muscles, enabling you to run faster for a given effort. So let us put an example: Imagine person A has a Vo2Max of 64ml*kg*min and person B has a Vo2Max of 52ml*kg*min and they are going to run a 8km race. The most likely thing that will happen is that person A will win because of the higher Vo2Max.

Now that we understood what Vo2Max is and how important it is in endurance events, I will talk about how we can improve it. But for that you will have to wait until my next blog 🙂



In the last blog I talked about how and why altitude affects endurance exercise but would altitude also affect short explosive exercise where oxygen is not a factor? Well, let us find out.

Most of you have probably heard that when we exercise we can use two systems: Aerobic and Anaerobic. Aerobic means that we need oxygen to produce energy and any event that last more than 60″ seconds is basically going to depend on that system for energy. Anaerobic, on the other hand, means we are able to produce energy without oxygen and any event that last 10″or less seconds is going to use mostly the anaerobic system.

So, would altitude affect anaerobic exercise? We  know now ( thanks to the last blog) that the partial pressure of oxygen is lower at higher altitudes but since we would be doing an activity that does not require oxygen that would not affect us. We also learned that at higher altitudes there is a lower air density. If there is a lower air density it means there is less resistance, meaning your running speed could improve!!

There you have it, since anaerobic exercise does not rely on oxygen and there is less air density, any exercise that does not last too long should not be influenced by altitude. And that is what happened exactly at the Olympic games of Mexico city in 1968. In most of the short duration-explosive events there was a big improvement!


Hope you enjoyed it.




I think many people have heard that exercising at altitude is harder than exercising at sea level but most people don’t know exactly why. I will try to explain that in this blog.

First we have to talk about atmospheric pressure and what it is and what it means. In simple words, atmospheric pressure is a measure of the weight of a column of air directly over that spot. At sea level, the weight of that column of air is greatest and it equals more or less to 760mmHG. Most of you will know that air is composed of Nitrogen 79.04%, Oxygen 20.93% and Carbon Dioxide 0.03%. These percentages remain constant regardless of altitude. So, at sea level where atmospheric pressure is 760mmHG, the partial pressure of Nitrogen would be 600.7 (79.04% of 760mmHG), of Oxygen it would be 159.1mmHG (20.93 % of 760mmHG) and 0.2mmHg for Carbon Dioxide (0.03% of 760mmHG). Ok, so as we start to climb the atmospheric pressure is going to decline, the percentages of the gases will remain constant but the partial pressure of each gas will be lower. This is because the air is less dense, and each liter of air contains fewer molecules of gas. Let’s look at some examples to visualize this:

1. Mexico city is at 2,210 meters, the atmospheric pressure there is around 585mmHG meaning that the partial pressure of oxygen would be 122mmHg ( 20.93% of 585mmHG);

2. Mount Everest is at 8,048 meters, the atmospheric pressure there is around 253mmHG, which would mean that the partial pressure of oxygen would only be 53mmHg ( 20.93% of 253mmHG).

So there you have the answer, since the air is less dense the partial pressure will be lower so every time you breath you will inhale less molecules of oxygen. If there is less oxygen you will get tired quicker. But does altitude affect exercises where oxygen is not a factor, like jumping??? I will talk about that in my next blog,,,

The best diet.

I usually do not do this but this time I will make an exception. Instead of wrtting a blog, I am going put a link to a video that talks about nutrition and diet from a scientific point of view. It is only 15 minutes long and it is explained in a simple manner. In my opinion one of the best videos I have seen. Hopefully you guys like it and learn something from it. . If the link gets blocked, all you have to do is go to youtube and look for Doctor Mike Evans.

¨Hitting the wall¨

You probably have heard of this expression before if you are a runner and may have even experienced it yourself. ¨Hitting the wall¨ usually happens around the 29th to 35th kilometer. The runner´s pace slows down considerably, the legs become very heavy and thinking often becomes hard and confused (now that I think about it, this last thing happens to me quite often). This happens because we basically run out of available energy.

The runner´s primary sources of energy during prolonged exercise are carbohydrates and fats. We have lots of stores of fat, around 70.000 to 75.000 kcla, even in a lean adult, but the fat metabolism requires a constant supply of oxygen, and delivery of energy is slower than that provided by the carbohydrate metabolism. The carbs reserves (glycogen), on the other hand, are quite limited and have only around 2.000 to 2.400 kcla, which happens to be enough energy to get us to kilometer 29-30. Since the body is much less efficient at converting fat to energy, running pace slows and the runner suffers from fatigue.To make things even worse the brain, which  only accounts for 2% of your weight and consumes 20% of your energy, gets its fuel source only from carbohydrates!!  So now next you ¨hit the wall¨you will know why that is. Hope you liked it. Till next time


Kenney L, Wilmore J, Costill D. Physiology of Sport and Exercise sixth edition, Human Kinetics,2015.

As I mentioned in my last post, scientist still don’t know why we get muscle cramps while exercising. The old theory was the electrolyte depletion and the new one is the muscle fatigue. I gave some flaws of the electrolyte theory, but this does not mean that I totally disregard that theory. As there are some people who actually lose salt at a rate five times faster than normal. Salts are essential to hydration despite of that mineral’s reputation for drying you out.  A body short of salts won’t deliver the water efficiently to the muscles. So even if you are drinking bottles and bottles of water, nothing will happen. The thing is that most people don’t lose salt so fast so, in my opinion, most of the exercise muscle cramps come from fatigue. There is also a difference between electrolyte depletion cramps and fatigue cramps. Electrolyte depletion cramps are much more serious, they affect more than one muscle and stretching won’t alleviate the cramp. Fatigue related cramps aren’t that serious, and usually by stopping the activity and stretching the cramp will go away.

So what can we do to try to avoid the muscle fatigue cramps? Go slower, decrease the intensity or train better, let me explain. We often get these cramps in competition and not while training. This is usually because, when we are competing, we are going faster or more intense than during practice due to the adrenaline or to due the mere fact that we are competing to get the best results. If the body is not trained to go at that intensity it will get tired faster, meaning a higher chance of getting a cramp.  And that is what the studies have shown, namely that the increased running speed is what predicts who will get the exercise associated muscle cramps. (1-5)

Hope you liked it.

  1. Schwellnus MP, Drew N, Collins M: Increased running speed and previous cramps rather than dehydration or serum sodium changes predict exercise-associated muscle cramping: a prospective cohort study in 210 Ironman triathletes. Br J Sports Med, 1-7, Dec. 9, 2010
  2. Schwellnus MP, Derman EW, Noakes TD. Aetiology of skeletal muscle cramps during exercise: A novel hypothesis. Journal of Sports Sciences, vol.15, pp 277-85. 1997
  3. Schwellnus MP. Muscle cramping in the marathon:aetiology and risk factors. Sports medicine. Auckland, NZ 2007.
  4. Schwellnus MP. Cause of exercise associated muscle cramps ( EAMC)–altered neuromuscular control, dehydration or electrolte depletion?
  5. Braulick KW, Miller KC, Albrecht JM, Tucker JM, Deal JE. Significan and serious dehydration does not affect skeletal muscle cramp threshold frequency. Br J Sports Med, 1009 Jun:43(6):401-8

The answer to this question is quite simply…… we still don’t know. Most people, even trainers, think that it is due to the loss of salts or electrolytes but in the past few years the scientific evidence out there clearly does not support this hypothesis. But most people still believe this thanks, in part, to the help of sports drinks.

This myth started almost 100 years ago in shipyards and mines, where workers were cramping up.  They did an analysis of their sweat which showed that it contained high levels of chloride (an electrolyte). So, they came to the conclusion that loss of electrolytes was the reason for the workers’ muscle cramping, along with dehydration. The problem with this is that they never checked the sweat of the people that were not cramping up. So, it sounded logical but this hypothesis had a couple of weak links.

  1. The first one being: When we sweat, we tend to sweat all over our body, meaning we are losing electrolytes equally in all  parts of our body. But somewhat surprisingly, exercise-associated muscle cramps only happen in the muscles that have been used extensively for the exercise. Kind of weird, right?
  2. When we sweat we lose much more water than electrolytes. In fact the loss of electrolytes is very low. Meaning that the concentration of electrolytes in our body is actually going to be higher than before doing the sport or activity. Also, two studies done on  ultramarathoners , showed that the runners who cramped up had a significantly lower sodium concentration (this means these runners were over-hydrated ), and lost less weight, and the more direct measures of the fluid in their blood showed they were better hydrated (1-4).  Amazing, isn’t it?
  3. Whenever we cramp up, we stretch and that usually makes the cramp go away for a while. So, if cramping is caused by loss of electrolytes or dehydration, how can simply stretching the muscle help us getting rid of our cramp?

Then why do we cramp up while exercising? Well, there is a new theory out there that basically says we cramp up because of fatigue. Let me explain: Muscle contraction is stimulated by a nerve, called the alpha motor neuron. One of the places this neuron gets its information from is muscle spindles and the golgi tendon organ.

1) Muscle spindles- We have probably all experienced the classic reflex, where a doctor or friend taps on the knee with a small hammer and you extend the leg. So, whenever your muscle is stretched too much, the muscle spindles activate and produce a muscle contraction (5).

2) Golgi tendon organ- Does the opposite, when it feels that a muscle is contracting too much, it will send a signal telling the muscle to relax (5).

Fatigue has been shown to increase the rate of muscle spindle and decrease the rate golgi tendon organ (5). Most muscle exercise cramps happen at the end of a race.

I will leave it at here for today. In my next blog I will talk about what we can do to try to prevent muscle cramps.




  1.  Schwellnus, M.P, Nicol R, Laubscher R, Noakes T.D Serum electrolyte concentrations and hydration status are not associated with exercise associate muscle crampint (EAMC) in distance runners. Brit J Sports Med 38(4): 488-92.
  2. Miller K, Knight K, Mack G, et al. Three percent hypohydration does not affect the threshold frequency of electrically-induced muscle cramps. Med Sci Sports Exerc. 2010;42:2056-2063.
  3. . Braulick K, Miller K, Albrecht J, Tucker J, Deal J. Significant and serious dehydration does not affect skeletal muscle cramp threshold frequency. Br J Sports Med. 2012;47:710-714.
  4. Sulzer N.U, Schwellnus M.P, Noakes T.D. Serum electrolytes in Itronman triathletes with exercise-associated muscle cramping. Med Sci Sports Exerc 3(7): 1081-85.
  5. Schwellnus M.P, Derman E. W, Noakes T.D. Aetiology of skeletal muscle cramps during exercise: A novel hypothesis. Journal of Sports Sciences, vol 15, pp 277-85, 1997.

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