Science Matters

This is part of a larger post that will come shortly on cannabidiol.

The best studies with the strongest evidence are designed to be the closest to what you want to know. For example, if you are a healthy and active person who wants to take CBD to reduce inflammation, hopefully there is a well-designed study in humans that examined just this. Preferably, a study like this: a cross-sectional study conducted on healthy and active people who take CBD (group 1) or a matched placebo (group 2) and biomarkers known to be associated with inflammation are compared after a certain number of weeks. This would provide good insight in to the benefits and risks of CBD use in relation to inflammation. Moreover, randomizing who is in each group is better and, if possible, blinding the subjects (or even the researchers) adds even more rigor to the study and confidence in the results. Hopefully other measures related to inflammation, such as diet and exercise, are controlled so you don’t have confounding influencers that would impact inflammation outside the influence of CBD. If not, interpretation of the results can be difficult or wrong if diet and/or exercise actually reduced inflammation but you think it was the CBD. Even within this in vivo (Latin for “within the living”) study design, hopefully the duration of the study is long enough to actually change things, and all human subjects complete the study, and the data is appropriately analyzed, and the results appropriately interpreted! There is a lot more to scientific studies than most people realize! Someone quotes a scientific article and it is more often than not considered to be a good study with accurate conclusions. But that is not always the case! Studies on humans can be difficult. I don’t think most people realize this.

There are also in vitro (Latin “within the glass”) and ex vivo (Latin “outside of the living”) studies where researchers isolate a tissue or cell from a human (or animal) and examine what happens and then speculate on whether these results will impact a human on a whole-body (i.e. in vivo) level. Lastly, there are animal studies (in vivo and in vitro), mostly in rats and mice, where they attempt to mimic human conditions of, say, inflammation (or anxiety, etc.) and then examine the results of CBD and speculate how it may or may not be similar and/or effective in a human.

The further you get away from testing what you really want to know, the weaker the evidence. So if a study showed that low doses of synthetic THC use in rats that were “depressed” from a Forced Swim Test (time of swimming to giving up in an enclosed water filled cylinder) activates a serotonin receptor (related to mental health), would you take THC (or a related cannabinoid like CBD) to help with depression? [1]. Not to belittle this study as it is interesting and shows promising results. But the next big step to say that CBD is an anti-depressant in humans requires more smaller steps (i.e. studies). Thus, you often see in conclusions that most studies end with: more research is needed.

There are many, many studies out there. A great way to understand the current consensus on a topic is to find review or meta-analysis papers. A meta-analysis is cool because other researchers within that specific field sift through studies to find the best ones that meet their inclusion criteria. For example, a meta-analysis by Whiting et al. [2] was conducted in 2015 searching databases for topics related to cannabinoids and clinical trials, adverse events, and depression. Out of 23,754 title and abstract screenings, they ended up with only 79 studies that met their inclusion criteria (randomized, clinical trials in humans) [2]. Of these 79 studies, only 1 examined anxiety disorder and zero for depression [2]; meaning that for these two important topics related to CBD use, there is little to no studies worth drawing conclusions from based on their inclusion criteria.

All this said, you have to be diligent in understanding the type of study and the implications of interpreting the results of such studies. Is this the utmost, best evidence? Is this good evidence? Is this weak evidence? That is why people like me, with a scientific background and research background, sift through the studies, papers, reviews & meta-analyses to inform you the reader. This of course takes trust. Am I qualified? I think so. Am I doing the best job possible? I aim to. For goodness sake, I am spending the time to explain this here [embedded within a larger post to come] where many writers don’t, which I think is important when making a decision on whether you should take CBD (or any supplement for that matter) or not. Plus, check my references, which I always include and so should all posts!

Pet-peeve: Some online articles cite in text and provide references (yay!), others don’t (boo!), and others make a citation in the text but don’t actually provide the reference at the end (what the hell?!).

I hope you learned something. I hope you understand how complicated this can be. But understanding at least what is explained above is very important to understanding recommendations for taking CBD, for taking supplements in general, and, in my opinion, understanding the relationship between research and … the universe.

More to come.

Contact me if you want to know more or have any questions!


1.     Bambico FR, Katz N, Debonnel G, Gobbi G. Cannabinoids Elicit Antidepressant-Like Behavior and Activate Serotonergic Neurons through the Medial Prefrontal Cortex. J Neurosci. 2007;27(43):11700-11711. doi:10.1523/JNEUROSCI.1636-07.2007.

2.  Whiting PF, Wolff RF, Deshpande S, et al. Cannabinoids for medical use: A systematic review and meta-analysis. JAMA - J Am Med Assoc. 2015;313(24):2456-2473. doi:10.1001/jama.2015.6358.

New year. New goals

Wow, it has been a while. My apologies. Some things in life over during the fall season sucked up my time.

First, happy new year!

I sat down with a friend in the new year and went over my goals for this year. One of those being this "Learn" blog. We decided that I should keep up the educational and scientific posts (which are fairly time intensive), but also be more flexible. Meaning, try doing some video blogs and expand the content.

So I am going to try that out. Look for more consistent, but also more flexible content in the future.



Beetroot Juice

This is an interesting and fun topic. Some of you may have heard of this or seen beetroot juice products for sale claiming many things. Is there truth to these claims? Let’s find out.

What it can do

There are two important and related results of consuming beetroot juice. One, it has been shown to reduce blood pressure. This is important for those who struggle with high blood pressure and in older populations. Two, it can make you more efficient. When I say this, I mean this. Efficiency gets thrown around a lot. “That runner has an efficient running form,” or “That runner needs to work on their form to become more efficient.” There is no way of knowing this by looking at someone and I plan to write a post on “Efficiency.” This is because efficiency is the number of calories (energy) it takes to work (exercise). Just because you look efficient, doesn’t mean you are efficient. On the other hand, beetroot juice truly has been shown to make people more efficient, meaning the energy cost to exercise was lower. To scientists, this is absolutely fascinating! In almost all circumstances, the amount of energy to perform work remains (relatively) constant. You go run at a 9 min/mi pace one day for 4 miles and you will burn a certain amount of calories. If you repeat this a couple days later in identical conditions, the energy used will be the same. But if you consume beetroot juice, the energy can be lower to do the same amount of work!

A little bit of the science

Beetroot juice contains a large amount of nitrates. Nitrate is converted to nitrite which is converted to nitric oxide which is a powerful vasodilator (opens up blood vessels). It is also thought that nitric oxide may play a role in the skeletal muscle performing the work by increasing its efficiency; how is still debated. The important thing to remember is that it is nitrate that is important and not necessarily beetroot juice. You can eat other vegetable sources including dark leafy greens.

Does bacon work?

I don’t know. I don’t know if anyone has examined that yet. Beetroot juice is a more healthy long term supplement anyways.

How much?

All that said, beetroot juice remains the most common form to supplement nitrate. Current recommendations state that you should consume 500 ml (the size of a normal plastic water bottle) 2-3 hours before a workout as this is when levels peak. Nitrite levels will decline and return to normal pre-supplement levels after 6-9 hours. In order to continually keep nitrite levels high in your system, you need to drink 500 ml twice daily (morning and evening). So you better like beets!

Who benefits the most?

The more endurance trained you are, the less likely a large effect. Scientists speculate that if you are endurance trained, you are already eating a healthy diet with vegetables that contain nitrate. Another reason may be that the response is minimal since you already have “maxed out” the beneficial adaptations to endurance training already. The only way to truly know is to be tested, but that is expensive. The good thing is that there are no known adverse effects. That said, studies need to investigate any possible adverse effects of long-term supplementation.


Nitrate is converted to nitrite by bacteria in your mouth! If you use mouth wash (and/or possibly gum) you kill off these bacteria and do not get the benefits! I’ll repeat that since it is important. If you use mouth wash or chew gum, you will likely not benefit from the supplement. You can still brush your teeth, but hold off on the stronger bacteria killing products.

Your urine and feces will be red-ish. Knowing this before you go is good so you don’t freak out.

My recommendation

It is my professional opinion, that if you want to try it then try it. If you can stomach the taste then use it and see how you feel. Test it yourself and try to control the conditions. Even if you are endurance trained, it is worth a try. The elite athletes that studies have examined are likely more fit than anyone reading this. We are talking about athletes with a VO2max of 70-80 ml/kg/min. This endurance level usually means you a paid endurance athlete or maybe an Olmypian. (See earlier post to learn more about the importance VO2max.)

Contact me if you want to know more or have any questions!


References and further scientific reading:

  • Boorsma RK, Whitfield J, Spriet LL. Beetroot juice supplementation does not improve performance of elite 1500-m runners. Med Sci Sports Exerc. 2014;46(12):2326-2334. doi:10.1249/MSS.0000000000000364.
  • Burke LM. To beet or not to beet? J Appl Physiol. 2013;115:311-312. doi:10.1152/japplphysiol.00612.2013.
  • Christensen PM, Nyberg M, Bangsbo J. Influence of nitrate supplementation on VO₂ kinetics and endurance of elite cyclists. Scand J Med Sci Sports. 2013;23(1):e21-31. doi:10.1111/sms.12005.
  • Larsen FJ, Schiffer T a, Borniquel S, et al. Dietary inorganic nitrate improves mitochondrial efficiency in humans. Cell Metab. 2011;13(2):149-159. doi:10.1016/j.cmet.2011.01.004.
  • Larsen FJ, Weitzberg E, Lundberg JO, Ekblom B. Dietary nitrate reduces maximal oxygen consumption while maintaining work performance in maximal exercise. Free Radic Biol Med. 2010;48(2):342-347. doi:10.1016/j.freeradbiomed.2009.11.006.
  • Nair KS, Irving B a., Lanza IR. Can dietary nitrates enhance the efficiency of mitochondria? Cell Metab. 2011;13(2):117-118. doi:10.1016/j.cmet.2011.01.013.
  • Pawlak-Chaouch M, Boissiere J, Gamelin FX, Cuvelier G, Berthoin S, Aucouturier J. Effect of dietary nitrate supplementation on metabolic rate during rest and exercise in human: A systematic review and a meta-analysis. Nitric Oxide. 2016;53:65-76. doi:10.1016/j.niox.2016.01.001.
  • van Loon L, Stephens F, Jones AM, et al. Sports Nutrition Conference London/Oxford 2012. In: Sports Nutrition. ; 2012:1-24.
  • Whitfield J, Ludzki A, Heigenhauser GJF, et al. Beetroot juice supplementation reduces whole body oxygen consumption but does not improve indices of mitochondrial efficiency in human skeletal muscle. J Physiol. 2016;594(2):421-435. doi:10.1113/JP270844.

The (Maybe Not So) Almighty VO2max: Part 2

Note: See Part 1 if you need some background.

Can my VO2max change?

Yes. It can go up (yay!) and down (boo!). Increases depend on your initial fitness and what type of training program you follow. Studies have shown in healthy people that VO2max can go up significantly in as little as 2-3 weeks, although most studies demonstrate increases in 6-9 weeks. The increase ranges between 5-20% depending on initial fitness and the type of training. But just as it goes up, it also goes down. If you don’t use it, you lose it within a few weeks. This means no activity or detraining.

For more competitive endurance athletes, studies following them over a season have shown no significant changes (up or down) in VO2max. Remember though that even when not competing, these types of athletes maintain a structured endurance training plan most weeks out of the year. Also, remember that these studies are looking for changes in groups to determine significant changes. As an individual you may see changes that are meaningful to you. But competitive athletes will see decreases with no training within 8 weeks. Yet Madsen et al. showed over 4-weeks that it takes just one 35-min high intensity training session per week (and that is it) to maintain VO2max in competitive athletes.


VO2max declines with age. Yep. Bummer. This is primarily driven by the fact that your maximum heart rate goes down with age. (Note: staying fit does not prevent your maximum heart rate from going down, it can slow the rate it goes down.) Just because your maximum heart rate and VO2max go down does not necessarily mean you will be slower. Why? … If you read VO2max Part 1, there are two other important factors associated with endurance performance: lactate threshold, and efficiency or economy.

Other Important Factors

Let’s say that you maintain your same fitness level, meaning your lactate threshold occurs at the same percent of your VO2max. If this happened, with a decrease in VO2max, then you’d get slower. BUT there is efficiency (or economy). There are limited studies that have looked at this over time since a longitudinal study like this is difficult to do. But there is a 5-year study of an elite woman runner whose 3000m time improved by 8% even though VO2max decreased by 9%. How? Her lactate threshold improved by 20% and her running economy improved by 11% over 5 years. To have an improved lactate threshold means you can maintain a higher speed since you are running at a greater percent of your VO2max. To have an improved running economy means you need less energy to maintain the same speed.

So you can see that VO2max is not so “almighty”. Yes, you need to have a high VO2max to be an elite athlete, but it is only one part of endurance performance.

Men and Women

Men typically have a 10% higher VO2max than women when normalized for body weight. This is because, biologically, women tend to have a lower haemoglobin concentration (associated to how much oxygen your blood can carry), higher body fat percent (relates to body weight), and smaller heart and lung size (relates to ability of heart and lungs to deliver oxygen). BUT this is true when the comparison is alike (or homogenous), meaning that you take a man who is recreationally active and compare him to a woman who is similarly recreationally active the man would likely have a higher VO2max. But, if you took a recreationally active man and compared her to a woman who is endurance trained, her VO2max would likely be higher. So size and training are important. If you compare the world’s best marathon male to a female than the male will likely have a higher VO2max.

Contact me if you want to know more or have any questions!


References and further scientific reading:

  • Galy O, Chamari K, Costes O, Hue O, Maimoun L, Manetta J. Maximal oxygen uptake and power of lower limbs during a competitve season in triathletes. Scand J Med Sci Sport. 2003;13(3):185-193.
  • Hopker J, Coleman D, Passfield L. Changes in cycling efficiency during a competitive season. Med Sci Sports Exerc. 2009;41(4):912-919.
  • Jones AM, Carter H. The effect of endurance training on parameters of aerobic fitness. Sports Med. 2000;29(6):373-386.
  • Jones AM. A five year physiological case study of an Olympic runner. Br J Sport. 1998;32(0306-3674 (Print)):39-43.
  • Joyner MJ, Coyle EF. Endurance exercise performance: the physiology of champions. J Physiol. 2008;586(1):35-44. doi:10.1113/jphysiol.2007.143834.
  • Klitgaard A. Effects of detraining on endurance capacity and metabolic changes during prolonged exhaustive exercise. 1993.
  • Madsen K, Pedersen PK, S DM, Klitgaard NA. Effects of detraining on endurance capacity and metabolic changes during prolonged exhaustive exercise. J Appl Physiol Appl Physiol. 1993;75(4):1444-1451.
  • Mendes TT, Fonseca TR, Ramos GP, et al. Six weeks of aerobic training improves VO2max and MLSS but does not improve the time to fatigue at the MLSS. Eur J Appl Physiol. 2013;113(4):965-973.
  • Passfield L, Doust JH. Changes in cycling efficiency and performance after endurance exercise. Med Sci Sports Exerc. 2000;32(11):1935-1941.
  • Term L, Training I. Detraining : Loss of Training-Induced Physiological and Performance Adaptations . Part II. 2000;30(3):145-154.

Compression Wear: Part 1

Keep it Tight

Compression wear or clothing is tight fitting, synthetic garments worn to (primarily) alter blood flow. They are primarily worn on the lower body, although compression garments for almost every part of the body can be found now. Compression garments came from medical/clinical research showing that graduated compression (more pressure at ankle and less pressure at knee) can enhance blood flow in patients who have issues with lower body blood flow. The reason you see it now in all kinds of sports is because blood flow is important to exercise performance no matter the sport. So... maybe compression garments can help in healthy, recreationally active or elite athletes as well?

But does it work?

Now we enter Pandora’s box. First question (a future Part 2 post), do compression garments enhance performance during exercise. Then (a future Part 3 post), do they enhance recovery from exercise. In each situation, it is important to understand if the exercise is endurance based (running, cycling, triathlons, etc.) or strength based (weight lifting, jumping, etc.) and is it high intensity (close to or above maximal exertion) like sprints, cross-fit, all-out 5K race, etc. or submaximal (“endurance” or “aerobic” or “cardio”) like training for a marathon. So you can see here that this topic is multifaceted and depends what type of athlete you are and for what purpose.

I’ll address these from what the scientific literature says. If you want to know the mechanisms—the physiological reasons why or why not compression wear impacts exercise performance—stay tuned for future posts.

Jumping to Conclusions

For those that want to know right now (!) ... the simple answer is wearing compression garments may help. That’s the best, vague answer. Compression garments aid in recovery from exercise more than during exercise. I have a pair of calf-high compression socks for recovery. I don't wear them during exercise. I've tried, but prefer to run without them. So it depends if you have money to spend. I know the conclusion isn’t great, but that is what the review of science shows.

More details and specifics to come on this topic!

Contact me if you have any questions or want to know more!


References and further scientific reading

  • Born D, Sperlich B, Holmberg H. Bringing Light Into the Dark : Effects of Compression Clothing on Performance and Recovery. Int J Sports Physiol Perform. 2013; 8: 4-18.
  • Engel FA, Holmberg HC, Sperlich B. Is There Evidence that Runners can Benefit from Wearing Compression Clothing? Sport Med. 2016; 46(12): 1939-1952.

The Almighty VO2max: Part 1

This physiological parameter, more than any other it seems, gets the most attention in endurance sports. It is certainly important, but it is only a piece of the puzzle which will be explained in future posts. It is one of the three primary predictors of endurance performance. The other are two are your percent of VO2max at lactate threshold (think of this as the fastest pace you can maintain for 1-2 hours without blowing up) and efficiency or economy (related to your “form”, but this is so much more than that!, as this is based on how much energy it takes for you to exercise).

What is VO2max?

VO2max is the abbreviation for “maximal oxygen consumption” and is reported in liters of oxygen per minute (l/min) or milliliters of oxygen per minute per kilogram (ml/min/kg or ml/kg/min) which is normalized (or standardized) based on body mass (weight). This value represents the greatest amount of oxygen your body can use (during cellular respiration) to synthesize energy (adenosine triphosphate, ATP) from food to generate muscle force and thus exercise. I skipped over a lot of steps, but that’s OK.

VO2max is important because it sets the upper limit of how much energy (ATP) you can synthesize from oxygen and food to exercise. Energy is key! The more energy (ATP) you can provide, the more force you can generate, the faster you can go. An analogy here is a vehicle. The engine uses gasoline (food) and oxygen to produce torque (force) to spin the wheels (exercise). An engine with a lot of horse power is bigger with more pistons (think a V8 or V12 engine compared to a V4 or V6 engine), usually has larger pistons, and also a bigger air intake. This engine is able to consume a lot of gasoline (food) and a lot of oxygen to produce a lot of horse power. The greater the horse power, usually the higher the maximal speed. If you limit the gasoline or air intake, the maximal horse power goes down and so does maximal speed. Just like our bodies, there are more factors involved related to performance (weight, aerodynamics, heat, etc.). But hopefully that analogy gets the point across. The higher the VO2max, the more energy you are able to synthesize from oxygen and food, the more force you can produce, and the faster you can go.

What are some VO2max values?

Here is a table from Powers & Howley, 2012 showing differences in VO2max between men and women and at different ages with values rounded to the nearest whole in ml/kg/min.

Did you notice how VO2max declines with age? This is partially due to a decline in maximal heart rate, which I will post on in the future.

Did you notice that men have higher VO2max values than women? This is because men typically have a less body fat and greater muscle mass (more muscle means more oxygen can be consumed to produce force), larger hearts (pump more oxygen rich blood to the muscles), and a higher haemoglobin concentration (able to carry more oxygen in the blood).

Endurance training increases VO2max and thus runners, cyclists, and cross-country skiers usually have higher values. World-class endurance athletes typically have values greater than 70 ml/kg/min, with some males reaching values greater than 90 ml/kg/min!

Why Should I care?

Here is a figure to depict why having a VO2max is important to endurance sports.

*Endurance training may improve efficiency, which we are ignoring for this example.

*Endurance training may improve efficiency, which we are ignoring for this example.

You can see here that the healthy, active person has a VO2max of 50 ml/kg/min and when exercising at this value is at 100% of their VO2max. This active person will only be able to exercise at this intensity for a few minutes. But when the elite person is exercising at 50 ml/kg/min, this is only 62% of their VO2max and would likely be considered a moderate effort for this person. In fact they would race closer to 85% of their VO2max which would be 59.5 ml/kg/min. So the speed the elite person could race at for at least an hour, the active person couldn’t even hold this speed for more than a few minutes!

 Are VO2max intervals the same as “anaerobic” intervals?

This gets complicated and tricky since coaching terminology is not always the same. But read on so you understand how these relate. VO2max intervals require an intensity and duration for you to reach VO2max. Usually they are between 3-6 minutes long with a rest break that is equal to or longer than the interval itself. These are hard!

Anaerobic means “without oxygen.” Think about this for just a bit and what you just read above. … VO2max intervals are actually mostly aerobic! When exercising at your VO2max, you are maxing out your aerobic system, meaning you are generating close to the maximum amount of energy (ATP) possible from food (almost entirely glucose at this intensity) to produce force to exercise. Can I keep going? Yes, but not for long. Can I go faster? Probably, but not for long. How? Because you use “stored” energy (ATP) that does not require oxygen at that given moment. In other words, you are relying on non-oxidative metabolism. (Note: This stored energy was originally generated using oxygen though.) But there is a limited capacity. It’s like using a nitro in a race car game. You are already at top speed but need to go faster. Nitro! Boom! Speed!…. But wait? I only have two more nitros! … So why is this type of interval exercise sometimes called “anaerobic”? When exercising at VO2max you are supplementing energy regeneration through non-oxidative pathways and this is why it is can be referred to as “anaerobic.” By performing this type of exercise, you are working on increasing or maintaining VO2max, as well as increasing or maintaining your body’s ability to supplement ATP using non-oxidative energy pathways. So bigger engine, and more nitros!

Contact me if you have any questions or want to know more!

Read Part 2 here!


References and further scientific reading

  • Bassett DR, Howley ET. Maximal oxygen uptake: “classical” versus “contemporary” viewpoints. Med Sci Sport Exerc. 1997;29(5):591-603.
  • Joyner MJ, Coyle EF. Endurance exercise performance: the physiology of champions. J Physiol. 2008;586(1):35-44. 
  • Levine BD. VO2max: what do we know, and what do we still need to know? J Physiol. 2008;586(1):25-34. 
  • Poole DC, Jones AM. Oxygen uptake kinetics. Compr Physiol. 2012;2:933-996.
  • Powers SK, Howley ET. Exercise Physiology: Theory and Applications to Fitness and Performance, 8th Edition. 2012; McGraw Hill: New York, NY.