My favorite aspects of exercise physiology :)

I took this class mainly because I was interested in the course material and it has paid off. Learning about the central governor and how the mind plays a role in feats of endurance has been my favorite part of the course. It is amazing to study the safety nets that our mind places on our body to prevent damaging itself from exertion. This extends from the diaphragm’s call for air in divers to the unconscious pacing that occurs in ultramarathons and bicep curls – there’s always more in the tank if the mind knows it is almost done! Most of this has come from reading Endure, but the discussions in class have been great.

From lecture, I really enjoyed learning about skeletal muscle. I liked learning about the differences between fiber types and how long it takes to convert from one fiber to another! Learning about the effects of training and detraining was super interesting! I particularly thought it was neat that the improvements seen early on are due to neurological improvements in motor unit recruitment and then later improvements are due to hypertrophy (in resistance training). I am a bit surprised that endurance training can inhibit mTOR and thus slow down muscle growth if you train both resistance and endurance. Too bad we don’t gain more muscle fibers during resistance and endurance exercise. That certainly would make gaining strength and endurance at the same time a lot easier!

One aspect of exercise physiology that I would have liked to learn more about would have been the physiological effects of sleep and recovery. Everyone says sleep is crucial to performing well during exercise and I am sure there are physiological reasons that would be interesting to explore. Overall it was a great class and I am glad I took it!

The desire to move is coded in our genes.

Hi class,


I found an article published in the New York Times on May 15th entitled “To move is to thrive. It’s in our genes.” This article caught my eye because I know that when I am in shape, it seems like everything goes well and this article says that might be part of our DNA.


Researchers at Texas A&M published a study in April that used big data and genetic databases to try to pinpoint the moment in human evolution when genes began coding for a desire to be active. They found 104 snippets of DNA that are associated with physical activity in people, six of which are known to produce proteins related to metabolism. The researchers found that these snippets of DNA are not common to other mammals, suggesting that humans’ desire and need to move may not be shared among all mammals. In fact, when compared with Neanderthals and Chimps, the snippets related to inactivity were more shared than those related to activity, suggesting the will to move is more human-specific.


Previous twin studies and genome-wide association studies have suggested that 50 percent of physical activity behavior in humans depends on genes. It’s important that this and the more recent study the article commented on are not about innate aerobic fitness or performance ability. Rather, they are referring to the simple desire and interest to leave the couch and get moving! In today’s world, many Americans live sedentary lives, contributing to our nation’s prevalence of Type 2 diabetes, obesity, heart disease, and osteoarthritis. Moving matters! This article suggests the need and desire to move may be specific to humans as chimps, who share much of our DNA, do not experience the same health detriment from a lack of physical activity.

The article is specifically interested in understanding when the genetic desire to move came about, as that could help researchers cross-reference how food availability and climate were changing at that period of time to help understand WHY (on an evolutionary scale) we have to move.


The Texas A&M researchers found that the snippets of DNA telling us to get moving likely found their way into our genome about 500,000 years ago when we were Homo erectus – before Homo sapiens existed! The author of this article acted like this was a surprising finding and that they expected the genes to have turned up only 10,000 years ago when people started subsistence farming. Personally, I am not surprised that these genes were selected for long ago because I would have expected them to be present when our ancestors needed to hunt nomadically to survive. It seems like the need to move would be much more important if your next meal was always running away rather than being grown out of the ground. I wonder if these genes are now simply vestigial. Many people see going to the gym as a chore, wouldn’t it be cool if they did not have to! They should talk to He Jiankui – the gene editor from China.


The article gives an important caveat – that they did not perform any experiments and cannot be 100% confident in their estimate of when the genes came out. I think this is a responsible caveat to report, although the study most definitely provides an interesting insight into how ancient the desire to move is! One criticism I have for the author is the title: “To move is to thrive. It’s in our genes.” The article did not discuss heavily how exercise benefits the human body and mind, just about how ancient and how human-specific the will to move is. Maybe a more appropriate title would be “Get off your couch! It’s in your genes.”


I looked up the scientific study in PLOS one that the article was based on (see below), and it seems that the author of the NY times article did a fairly good job summarizing. A couple things left out of the summary were: (1) that most of the physical activity SNPs were in intron regions (not protein coding) and (2) that there actually IS great conservation of these genes between Neanderthals, chimps and Homo sapiens – it’s just that Homo sapiens experienced some evolutionary pressure to regulate physical activity more (as a result of mutations).

Overall it was an interesting read!


Thanks for reading!


Caffeine and exercise performance

Hi everyone,

Who had a cup of coffee this morning? One of the reasons people consume 2.25 billion cups of coffee a day (1) is because of its caffeine content. Take college students for example – you drink a cup of coffee before a sports game and you see improved performance. Is it a coincidence? My friend last year used to drink an iced coffee before every baseball game saying that he hit more home runs doing so. Is it simply superstition? I wanted to find out for myself.

It is important to note that coffee and caffeine are not the same. Caffeine is present in coffee, but consuming pure caffeine has different effects on performance then when consumed via coffee (2). It was found in one study that consuming pure caffeine improved the endurance of high quality runners from 32 min (at 10 km pace) to 41 min, while consumption of regular coffee had no effect (3). Caffeine is a trimethylxanthine and is catabolized by the cytochrome P450 system in the liver to dimethylxanthines. Consuming pure caffeine correlated with expected increases in free fatty acids (FFA) and epinephrine which could be tied to performance (3). While this study suggested that pure caffeine improved endurance but coffee did not, other studies have found coffee to also be ergogenic (2).

Many studies have shown that caffeine can be ergogenic in endurance activities where fatigue sets in between 30 and 60 min (2). Even if fatigue is at 30 min, it is unlikely that muscle glycogen has been depleted. One study showed that over half of the muscle glycogen remained at fatigue at 30 min, suggesting it is not the limiting factor regarding endurance here (2). So what about for longer feats of endurance? Ivy et al. had individuals perform 2 hours of
cycle exercise and, after caffeine ingestion, the participants generated a 7.3% greater total power output (4). This is not the only study to show a similar result in long distance, endurance exercise – in fact there are many (2). So, what about short, high intensity exercise? Less consensus has been placed here – while one study showed improved high intensity endurance, another showed no difference in caffeine vs. non-caffeine subjected participants (2).

There is much more research to sort through – about strength, endurance, power, etc. For my presentation, I will continue to sort through this research, but it is already readily apparent that caffeine does affect human performance in some, if not all, athletic and exercise endeavors. It is even more interesting that the dosage of caffeine necessary to improve performance may be lower than the acceptable standards of performance enhancing drug regulation committees of the Olympics (2).

Overall, I am excited to continue to tackle this issue and conduct my own correlative/anecdotal studies – I will see if I can’t repeat some of these findings by seeing how drinking coffee before a workout affects my own performance. I also cannot wait to hear about everyone else’s topics!

  1. Nieber, K. (2017). The Impact of Coffee on Health Author Pharmacokinetics and Mode of Action Bioactive Components in Coffee. Planta Medica, 83, 1256–1263.
  2. Graham TE. (2001). Caffeine and Exercise: Metabolism, Endurance, and Performance. Sports Medicine. (11):785-807.
  3. Graham TE, Hibbert E, and Sathasivam P. (1998). Metabolic and exercise endurance effects of coffee and caffeine ingestion. Journal of Applied Physiology. 85(3):883-9.
  4. Ivy JL, Kammer L, Ding Z. Wang B, Bernard JR, Liao YH, and Hwang J. (2009). Improved cycling time-trial performance after ingestion of a caffeine energy drink. International Journal of Sport Nutrition and Exercise Metabolism. 19(1):31-78.

The accumulation of lactic acid is disadvantageous for the human body.

Think back to when you first learned about lactic acid (now known to exist in the body as lactate). The context was probably not a good one. In fact, it was probably negative because it meant you couldn’t run as fast as you wanted and that you would lose to your siblings in tag.

The fact of the matter is that lactate prevented you from performing as well as you would have liked. Lactate accumulation is without a doubt disadvantageous for the human body and to argue it as advantageous is to simply ignore a fundamental fact of its existence.

Fatigue commonly occurs during intense exercise and can be induced by factors such as oxidative stress, dehydration and lactic acid accumulation in the muscles.1 Lactic acid accumulation in the muscles can cause intracellular pH to decrease by as much as 0.5 pH units. This acidosis stimulates fatigue by slowing down energy metabolism in the human body (1).

Such fatigue is not confined to the muscle that is exercising. Elevated lactic acid in the blood causes declined performance, even when you go from arm to leg exercise (2). Raising blood pH after it has been reduced by lactic acid has been shown to improve performance and this further supports the correlation of lactic acid with declined performance (2). The reason may be due to the disruption of calcium release and reloading of the sarcoplasmic reticulum which may be caused by lactate and H+ ions (2).

The method of lactic acid incubation, which has been used by some to suggest the benefits of lactate, does not accurately model what takes place during exercise. One deficit is that such experiments model a decreased transmembrane pH gradient when in vivo there is an increase in this gradient in skeletal muscle cells. (2)

Lactic acid and fatigue are correlated. Additionally, getting rid of lactic acid (efflux) is associated with greater performance and the ability of the body to perform efflux can be ascertained with training (2). If lactic acid goes hand in hand with fatigue, getting rid of it improves performance, and the body’s ability to efflux can be improved with training, it seems reasonable to conclude that lactic acid is disadvantageous to the body. If it were advantageous then getting rid of it would cause a decline in performance, not an improvement.

A study done on patients with chronic fatigue syndrome (CFS) showed that these individuals presented with an increase in aerobic Gram positive intestinal bacteria (3). What was interesting was that these bacteria produce D- and L-lactic acids from glucose metabolism. D-lactic acid is thus found elevated in the serum and is associated with cognitive dysfunction and neurological impairment (3). While this study is not directly related to exercise, it shows that chronic lactic acid accumulation can result in chronic fatigue syndrome. Lactic acid accumulation is disadvantageous for these individuals and similarly for healthy, exercising individuals.


  1. Halim H.H., Dek M.S.P., Hamid A.A., and Jaafar A.H. (2017). Fatigue onset through oxidative stress, dehydration and lactic acid accumulation and its in vivo study using experimental animals. Journal of Advanced Review on Scientific Research. 35(1):1-12.
  2. Lamb G.D., Stephenson D.G, Bangsbo J., and Juel C. (2006). Point:Counterpoint: Lactic acid accumulation is an advantage/disadvantage during muscle activity. Journal of Applied Physiology. 100:1410-1414.
  3. Sheedy J.R., Wettenhall R.E.H., Scanlon D., Gooley P.R., Lewis D.P., McGregor N., Stapleton D.I., Butt H.L., and Meirleir K.L. (2009). Increased D-Lactic Acid Intestinal Bacteria in Patients with Chronic Fatigue Syndrome. In Vivo. 23(4):621-628.

Tommy’s week 2 blog post

Hi class,

As some of you know, I am on the Crew Team here at Union and was a very active member until I separated my shoulder last term. Crew has pushed the boundaries of my cardiovascular and endurance performance. This past fall, the team and I competed at a few regattas before wrapping up for winter break. I wanted to come back from winter break as a more powerful rower, so I honestly just worked out like crazy – lifting weights and doing cardio. I came back and set a new personal record on the erg (rowing machine) every time I sat on one. What helped me perform better was that I pushed back the display screen so I couldn’t see how I was doing throughout the pieces. Instead of working for a number, I was listening to my body and pulling however hard my body could. I really couldn’t believe how well I was performing and it seemed the harder I worked, the harder I wanted to work! This also proved to me that your mind plays a huge role in restricting or enhancing your performance. When I stopped my mind from convincing me that I was tired, I realized that I could row harder, longer.  

I think that the mechanisms that govern performance during exercise (on a cellular or organismal level) may be reflections or even exaggerations of what takes place on a normal basis. When you put the body under stress to metabolize faster, it might help us highlight what takes place on a day to day basis. Here are a few other thoughts: (1) we already talked about negative feedback loops like the pH of the blood and respiration rates, so I am guessing that feedback loops in general play an important role in exercise physiology. I have noticed in my other classes that feedback loops pop up a lot in biology, so maybe studying them in exercise physiology will help us understand how they work in other biological systems. (2) Also, maybe studying comparative exercise physiology can help us characterize phylogenetic trees which would help biologists understand evolution further! And, (3) on Wednesday 4/3 we talked about sensors, integrators and effectors. Studying how these biological components work and communicate with each other may help us understand what occurs on a biochemical level. Or maybe it is the other way around, understanding what takes place biochemically can help us understand exercise physiology to a greater extent.

It seems that in all of biology, structure is inevitably related to function. To understand physiology we must first understand anatomy of the systems we will study. This is where pre-existing knowledge of biology, biochemistry, and neuroscience can come into play. I’m excited to take physiology to the next level – studying it when the body is put to stress (i.e. exercise). How much of our exercise physiology can be explained by what our ancestors physically needed to do to survive? Chasing down big game might explain our great long-distance endurance running ability. In this way, I can see history playing an important role in exercise physiology. I believe just having had discussions in previous upper-level science classes will help make our discussions in this class great – practice makes perfect. I can even see the material in BIO 112 – anatomy and physiology of the respiratory and cardiovascular systems – helping to contribute to our discussions in this class. Maybe also knowing the pKa’s of molecules such as carbonic acid – learned in organic chemistry and biochemistry – will help me contribute to discussions. Similarly, interactions of molecules must play a role in exercise physiology! I’m sure that learning back to front about proteins in BCH 382 and lipids and carbohydrates in BCH 380 will help in exercise physiology! These are the fuels that our muscles can use to power acute or prolonged exercise. Can’t wait to learn more!

See you all in class tomorrow,