Common Triathlon Training Metrics



Over the past two weeks I have outlined how to conduct a heart rate test and a functional threshold power test; but, I realized that I should have started from the beginning. What are the various training metrics that a triathlete should use?

Coaches, athletes, and endurance sport authors love to talk training metrics and terminology. Lactate threshold. VO2max. Cardiac output. Heart rate. Power. Rate of perceived effort. The list can go on and on…

Let’s look at a few key metrics that any triathlete or endurance sport athlete should understand, or at least a basic understanding.

  • Heart Rate – The very basic definition of a heart rate is the number of heartbeats per unit of time. Heartbeats are created when blood flows through the heart and the values open and close creating an audible sound. The normal human heart beats at 60-100 beats per minute (bpm). This, of course, depends on various factors such as fitness, age, stress, etc. Heart rate in fitness is an important metric because it can measure an athlete’s fitness. Through regular endurance training, the heart becomes stronger and thus can pump more blood with each beat. As a result, the heart doesn’t have to work as hard, and the athlete’s heart rate at rest and during exercise will be lower. Measuring an athlete’s heart rate over time is a good way to measure improvement in an athlete’s endurance fitness. See how to conduct a heart rate test for more information on heart rate-based training.
  • Cardiac Output – Cardiac output is measured as the amount of blood that the heart pumps through the body at a single minute. An increase in cardiac output is important because more blood is delivered to the important organs, such as the brain and liver. Cardiac output increases with regular endurance training. During endurance sports, cardiac output is an important metric because it means that more blood is delivered to the working skeletal muscles during a workout. As a result, more oxygen is transported to the muscle cells to produce energy and other metabolic waste by-products are removed from the working muscles more rapidly.
  • VO2max – Endurance training not only improves cardiovascular fitness, but also improves lung capacity during exercise. Endurance training generally improves an athlete’s respiratory rate (breathes per minute) and tidal volume (amount of air per breath). Improvements in respiratory rate and tidal volume can contribute to an increase in maximal oxygen uptake, also known as VO2max. VO2max is defined as the highest volume of oxygen that a person’s body is capable of taking in and using during aerobic energy production. An improvement in VO2max is important for endurance athletes because it means more oxygen is available to working muscles for energy production during exercise.
  • Lactate Threshold – Lactate threshold represents the point at which the athlete’s body requires a greater contribution from the glycolysis energy system (anaerobic system) and a smaller contribution from the oxidative phosphorylation energy system (aerobic system). At this point, lactate production exceeds the lactate removal rate and blood lactate levels increase. One of the primary goals of endurance training should be to increase an athlete’s lactate threshold.
  • Power – Power is primarily a cycling metric. It is simply defined as the rate of doing work, where work is equal to force times distance. Power is measured via a power meter on a bike. See How to Conduct a Functional Threshold Power test for more information on power-based training.
  • Rate of Perceived Effort – Rate of Perceived Effort, or RPE, is a psychophysiological scale, meaning that it calls on the mind and body to rate one’s perception of effort. The traditional scale called the Borg Scale is based on a scale of 6-20, where a score of 6 is equivalent of no exertion and a score of 20 is equivalent of maximum exertion. Many coaches and trainers, myself included, will use a scale of 1-10 for easier understanding by the athlete/client.

Above are several common exercise physiology and training metrics terminology that are often thrown around by athletes, coaches, and endurance sport authors. Of course, there are many more that we could discuss.

~ Happy Training! 

Book Review: Fat Chance

Looking for a good book? This is one MUST READ book! I enjoy listening to podcasts while working sometimes. My favorite podcast is Vinnie Tortorich, America’s Angriest Trainer. I HIGHLY recommend you listen to his podcast and then go out and buy his bestselling book, Fitness Confidential. I will be doing a book review of that very shortly. Vinnie has always recommended Dr. Robert Lustig’s Fat Chance: Beating the Odds Against Sugar, Processed Food, Obesity, and Disease on his podcast and after IMLP I finally had some free time to pick it up and finish it.

Source: Amazon

Source: Amazon

I’ve read a lot of books within the past month and Lustig’s is by far the best one to read. I think this book should even be a required reading book in high schools and college. That’s how much I think everyone needs to read this book. Go buy it. Now!

Who is Dr. Lustig? Well, he is an internationally renowned pediatric endocrinologist who has spent the past 16 years treating childhood obesity at some of the top hospitals in the world, such as St. Jude’s Children’s Hospital and UCSF Benioff Children’s Hospital. Sooo… I would say that he knows his shit better than those Jillian Michaels and Dr. Oz characters.

Dr. Lustig became famous for his at-the-time, very controversial you-tube video called “Sugar: The Bitter Truth.” And, yes, I think you should watch that too. Fat Chance documents the science and politics that have led to the current obesity pandemic that no longer just affects the United States, but the entire world. I went on a medial mission to Costa Rica and Nicaragua in 2011 and I was surprised beyond belief the number of overweight and obese people and the number of fast-food joints in those countries. Hell, Costa Rica has a Denny’s!

Lustig reveals and outlines all the bad research that has been conducted over the years by the government and big food. Personally, I think a lot of those scientists who were involved in many of those studies should have their PhD’s removed. It’s rather disgusting how many people will sell-out to the food industry and politicians. Ok, end rant.

The book begins by setting up a valid argument why the government’s view of “calorie in, calorie out” is bullshit. I hate that term. When discussing food with my clients I always ask them “what is a calorie?” No one has yet to answer correctly. It’s because we have been brainwashed over the years to think of food as calorie in, calorie out. That’s how you’re suppose to lose weight, right? Wrong! Believe me, I was one of those people for a long time too, but the more I read (from reputable and educated sources!!) the more I learn that I have been completely duped all my life. Lustig is an endocrinologist meaning that he is a specialist in hormones and the biochemistry of the human body.

Lustig talks a lot about hormones, ya know, since he gets hormones. Hormones have a profound effect on our metabolism and how we view food. Fat Chance outlines ways to readjust our key hormones that regulate hunger, reward, and stress. That is done mainly by eliminating sugar. Sugar is an addictive toxin to our bodies. We live in a society today that thinks dietary fat is bad. Low-fat this and low-fat that. Well, guess what happens when you remove fat from food products? The food tastes like crap and the manufactures pump it full on sugar. Read the book and find out why sugar is bad for you. I’m serious, do it.

The evolution of nutritional science is what really fascinates me. Back in the early to mid-1900’s we got the science right. And then big food and some idiots got involved. The leading cause of death today in the United States is heart disease, but in the next decade or so we will see that shift to diabetes and other metabolic-related diseases, which heart disease can be considered one. In 1957 John Yudkin, a British physiologist and nutritionist, postulated that a dietary component caused heart attacks. By 1964, through natural observation studies he theorized that the consumption of sucrose was associated with heart disease. Yudkins published numerous papers on the biochemistry of sucrose and was the first person to warn us that excessive consumption could lead to heart disease, diabetes, GI diseases among other diseases.

Now, back in the United States we have Ancel Keys, a Minnesota epidemiologist. In the early 1950s Keys spend some time in England where we witnessed a large rise in heart disease. The typical English diet consisted of high fat and high cholesterol items, such as fish and chips. He noticed that those who are well fed in both the US and UK were those who could afford meat, but also seemed to suffer the most from heart disease. In the 1960s and 1970s Keys published numerous studies indicating that heart disease patients had higher cholesterol levels than non-heart disease patients. In 1980 Keys published his “Seven Countries” study, a 500-page paper that concluded that dietary fat was the single cause of heart disease. Which, the United States government and medical community has since run with. However, there are four major problems with his thesis.

The first being that his Seven Countries study started out as a Twenty-two Countries study. The seven countries he used in his study were: Japan, Italy, England, Wales, Australia, Canada, and the US. The relationship between dietary fat and heart disease looked quite convincing when the data was plotted. However, when he plotted the other countries (Austria, Ceylon, Chile, Denmark, Finland, France, Germany, Ireland, Israel, Mexico, Netherlands, New Zealand, Norway, Portugal, Sweden, and Switzerland), the correlation was almost non-existent. He also actively chose not to include indigenous tribes, such as the Inuit, Tokelau, and Maasai and Rendille, who eat only animal fat and have the lowest prevalence of heart disease on the planet. How’s that for science? Second, the role of dietary fat in heart disease is complicated by trans fat, which has signficant scientific studies to link it to metabolic syndrome. The use of trans-fats peaked during the 1960s and most likely were not considered a variable by Keys.

Third, if you look at the correlation itself, it is a problem. Japan and Italy eat the least amount of saturated fat and have the least amount of heart disease. But, they also eat the least amount of dietary sugar out of all the countries included. How do you know if it’s the sugar or the fat causing heart disease? Fourth, Keys admits that he correlated sucrose with saturated fat, but it was not important enough to him to remove sucrose from the equation. When one completes a multivariate correlation analysis, a common statistical tool that determines whether A causes B regardless of the impact of C, D, and E, one has to do the calculation both ways. In other words, Keys would have had to hold sucrose constant and show that dietary fat still correlates with heart disease. Basically, Keys used bad science. And then the government took it and ran with the idea.

This is just one of the studies Lustig discusses in his book. He discusses many more that are just as interesting. The end of the book concludes with two sections. One is on the personal solution and the other is on the public health solution. I absolutely loved the public health section because I am a public health professional. In society today we have this notion that obesity is an individual problem. That person eats too much, doesn’t exercise and it’s their fault they are fat. Lustig will tell you that’s rarely the problem. The public health section discusses ways as a society that we can conquer the impending obesity pandemic.

Overall, you will be crazy not to read this book. Out of all the books I have read this year, this is by far one of the best ones out there. It will change your view of nutrition and the obesity epidemic. Lustig gives you the science that backs up his claims. This isn’t a diet book written by some bimbo Hollywood trainer on how to lose 10-lbs in 10 days. It’s a real book based on real science that will open your eyes and mind to the current nutritional crisis in the United States.

What are you waiting for? GO BUY THE BOOK! 🙂

~ Happy Training!

Nutrition Tuesday (Wednesday): A Look at Carbohydrates

Yesterday I gave an overview of each of the macronutrients needed by the human body for survival. Today I will provide a more in-depth discussion of carbohydrates. I could spend days talking about carbohydrates because there are so many things to talk about, but today I just plan on discussing what exactly a carbohydrate is and what it does in the human body. In the future I plan to discuss other topics such as the glycemic index and how much carbohydrates you should include in your diet (although you should really consult with a registered dietitian to figure out what is best for your body and health). 
Carbohydrates are groups of molecules that are comprised of carbon, hydrogen, and oxygen atoms. Carbohydrates are subdivided into three main categories: monosaccharides, oligosaccharides, and polysaccharides(1). 
Monosaccharides (“mono” = one, “saccharide” = sugar) are the simplest carbohydrate molecules. These simple carbohydrates often have a sweet taste and are classified by the number of carbons that make up their physical structure(1). The three most important nutritional monosaccharides are glucose, fructose, and galactose. Glucose is the most common mechanism for transport of carbohydrates in the body and some people refer to glucose to as “the blood sugar”(1). Glucose is a naturally occurring sugar in many foods and also is the end product of the breakdown of more complex carbohydrates. Glucose can be easily broken down by the body and can be 1) used as a fuel substrate to supply energy to the body, 2) stored as muscle or liver glycogen, or 3) converted to triglycerides and stored for later use by the body(1). 

Fructose is another simple carbohydrate. It is found in fruits, table sugar, honey, and high fructose corn syrup. Table sugar, corn syrup, and honey all contain glucose and fructose, but in differing amounts. During digestion, table sugar is broken down into 50% glucose and 50% fructose(2). High-fructose corn syrup (HFCS) digests into about 55% fructose and 45% glucose. Fructose has come under scrutiny in recent years because of the obesity epidemic in our country. HFCS is made using chemical processes that first convert cornstarch to corn syrup and then convert 42-55% of the glucose to fructose to make it taste sweeter(2). Some research has indicated that fructose is digested, absorbed, and metabolized differently than glucose in ways that favor fat production. The jury is still out on fructose; however, it’s best to avoid soda and other crap that contains HFCS. 
When monosaccharides bond together, they can form more complex carbohydrates referred to as oligosaccharides. A majority of oligosaccharides are disaccharides, or double sugars. All disaccharides contain glucose and generally are represented by sucrose, lactose, and maltose(1). Sucrose is commonly called table sugar, beet sugar, or cane sugar. Sucrose contains one glucose and one fructose bonded together. Another common disaccharide is lactose, which is formed from the bonding of glucose and galactose. Lactose is commonly referred to as the “milk sugar” because it is only found in milk from lactating animals(1). Lactose can be a difficult disaccharide for some people to digest (like me!) and can result in excessive fluid and gas build up in the bowels, bloating and cramping(1). The third most common disaccharide is maltose, which is created by the bonding of two glucose molecules. Maltose is commonly called malt sugar and is produced when seeds sprout(1). The sprouting process of plants can be altered by heat in the process called malting and is the first step in the production of alcoholic beverages. 

Polysaccharides are considered to be complex carbohydrate molecules. Generally, polysaccharides are linear or complex branching chains that are composed of more than 10 monosaccharides bonded together. The two most common plant polysaccharides are starch and fiber. Starch is the storage form of carbohydrates in plants and can be digested by humans. Fiber is considered a non-starch structural polysaccharide and may be the most abundant organic molecule on the plant, but it cannot be digested by humans. The primary animal polysaccharide is glycogen. Glycogen is either stored in the skeletal muscle or liver and is composed of subunits of glucose(1). One unique characteristic of glycogen is its branched structure. Generally, a glucose branch occurs on every 8-12th glucose subunit. This branching of glycogen is very important because it allows for very rapid breakdown of the glycogen molecule into its glucose subunits to be used for energy by the body. 


As previously discussed last week, carbohydrates, mainly in the form of glucose, are used by the body as fuel. Glycolysis is the metabolic pathway that results in the breakdown of blood glucose to produce ATP. Glycogenolysis (which I did not discuss last week) is the process which glycogen stores are broken down to produce ATP. Glycogenolysis is essentially considered the same pathway basic pathway as glycolysis, but each differ in the entry point in which they enter into the metabolic pathway. Generally, because of each enters the pathway, glycogen yields three molecules of ATP compared to glucose metabolism of two ATP molecules(1).


  1. Antonio J et al. Essentials of Sports Nutrition and Supplements. Totowa NJ: Human Press, 2008.
  2. Clark N. Nancy Clark’s Sports Nutrition Guidebook, 4th Ed. Champaign, IL: Human Kinetics, 2008.

Nutrition Tuesday: What You Need to Know About Human Metabolism

NOTE: I have decided to start a series of blog posts on Tuesdays called “Nutrition Tuesdays.” My goal is to educate more people on the importance of proper nutrition and also dispel common myths that plague the health and fitness industry. I would like to point out that I am not a registered dietitian or nutritionist (although I hope to be in a couple of years!) and thus if you have any serious concerns or questions about your health please seek professional advice. My goal here is to share information as I learn it through my studies.

Metabolism is essential to sustain life. A majority of people do not understand human metabolism and thus give out bad advice or misinformation. Human metabolism is a very complex topic and one that best needs a degree in biochemistry to fully understand. As someone with a biochemistry degree I free comfortable and qualified to give you the basic understandings of human metabolism to help you better understand the importance of proper nutrition in sports and life. 
Metabolism is a series of chemical reactions that occur at the cellular level in your body that convert fuel from food into the energy your body needs to do everything from moving to thinking to growing and even sleeping. Metabolism is a constant process that begins when we’re conceived and ends when we die. At any given time, there are thousands of metabolic reactions happening throughout your body that keeps your cells healthy and working!
Metabolism actually begins with plants! Through photosynthesis, plants take energy from the sun and create sugars from water and carbon dioxide. 
6CO2 + 6H2O + light energy -> C6H12O6 + 6O2
When people and animals eat plants they take in energy in the form of sugar along with other important vitamins and minerals. Eating lots of fruits and vegetables are important in your diet! Once food is digested it must be broken down in order for the body to absorb it and use it to fuel its cells. 
Molecules in our digestive system called enzymes break foods down into their building blocks, or simplest forms. Proteins are broken down into amino acids, fats are broken down into fatty acids, and carbohydrates are broken down into simple sugars. These “building blocks” can then be absorbed into our bloodstream and distributed to cells throughout our bodies. 
There are actually two forms of metabolism and the body has to perform a balancing act between the two. Anabolism (constructive metabolism) involves changing small molecules into larger, more complex molecules of carbohydrate, protein, and fat. Catabolism (destructive metabolism) is the process that produces the energy that all cells require to function. Cells break down large molecules to release energy. This energy provides fuel for anabolism, heats the body, and enables the muscles to contract and in return move your body! 
Now for the really fun stuff! As a biochemistry major in college I had to memorize the various cycles of metabolism, but I’m just going to give you a general overview because you really don’t need to know the specific enzymes and substrates that are involved in the processes. Carbohydrates, lipids (fats), and proteins constitute the majority of foods we eat. As mentioned above, carbohydrates are broken down into monosaccharides, or simple sugars. Glucose is the main source of fuel of the body; however, it is not the sole fuel for metabolism! Lipids or fats are broken down into monoacylglycerol and long-chain fatty acids. Proteins are broken down into small peptides and amino acids.   
Adenosine-5’-triphosphate (ATP) is often called the “molecular unit of currency” of intracellular energy transfer because it transfer chemical energy within cells for metabolism. There are two forms of ATP synthesis: oxidative phosphorylation and substrate-level phosphorylation. 
Oxidative Phosphorylation
Oxidative phosphorylation is the main mechanism of ATP synthesis in most human cells. If you think back to your high school chemistry class you remember that all atoms, and thus all molecules are made up of protons, neutrons, and electrons. The exchange or sharing of electrons between two or more atoms is the main cause of chemical bonding. You may also recall reduction-oxidation, or redox reactions. Oxidation is the loss of electrons and reduction is the gain of electrons. You can remember this as LEO (lose electrons oxidation) says GER (gain electrons reduction). During oxidative phosphorylation, electrons are transferred from electron donors to electron acceptors. These redox reactions release energy that is used to form ATP. In humans, these reactions take place in the mitochondria of cells, or commonly referred to as the “cellular power plants.” These redox reactions are carried out by a series of protein complexes in the mitochondrial walls that is ultimately called the electron transport chain (ETS). The energy released by electrons flowing through the ETS is used to transport protons (the positive charge) across the mitochondrial walls to generate an electrical potential across the wall. The protons are allowed to cross the wall through a large enzyme called ATP synthase. This enzyme uses the energy from the protons to generate ATP from adenosine diphosphate (ADP) by adding a phosphate group through a phosphorylation reaction. 
This ETS is actually in a plant cell because of the Photosystem, but it is pretty much the same pathway as in an animal cell. Note: This is a simplified verison of the real pathway.
Substance-level Phosphorylation
In aerobic (with oxygen) respiration all product’s produced by the degradation of carbohydrates, proteins, and fats converge to a central metabolic pathways called the Tricarboxylic Acid Cycle (TCA Cycle). It is also called the Kerb’s Cycle or the Citric Acid Cycle. Through the catabolism of sugars, fats, and proteins, a two carbon product called acetyl-CoA is produced. In the TCA Cycle, acetyl-CoA is oxidized to CO2. The cycle consists of 8 reactions that ultimately produces ATP and reducing agents that will donate their electrons in the ETS. For each molecule of glucose, two ATPs are produced indirectly from guanine triphosphate (GDP). However, the number of ATPs and amount of reducing agents will depend if fat or protein enters the TCA cycle. All of the molecules that enter the TCA cycle must be converted to acetyl-CoA before any reactions can occur. 
Here is a good animation of the TCA Cycle: How the Krebs Cycle Works

Glycolysis is the breakdown of carbohydrates, either glycogen stored in the muscle or glucose delivered in the blood, to produce ATP. During glycolysis, one glucose molecule is degraded into two pyruvate molecules. During the initial phase of glycolysis, two molecules of ATP molecules are actually consumed to active glucose and another molecule, called fructose-6-phosphate. The end result of glycolysis is 2 ATP molecules and two pyruvates, which are transported to the mitochondrial matrix to be converted to acetyl-CoA. 
Fat Oxidation
Fats are broken down to fatty acids where they can circulate and enter muscle fibers. Free fatty acids enter the mitochondria, where they undergo beta oxidation, a series of four reactions that break fatty acids down and form acetyl-CoA. 
Amino Acid Oxidation
Proteins are not a significant source of energy, but can be degraded into amino acids by various metabolic processes. Before amino acids can be metabolically useful, the nitrogen must be removed. Also, 20 different amino acids exist and each one has its own unique degradation pathway. The major amino acids that are oxidized in skeletal muscles appear to branched-chain amino acids (leucine, isoleucine, and valine).  
Here is a summary of Human Metabolism
Metabolism is a complex, multistep biological system that is essential to life. It is important to understand that energy stored in the chemical bonds of ATP is used to power muscular activity. The replenishment of ATP in human skeletal muscle is accomplished by three basic energy systems: (1) oxidative phosphorylation, (2) glycolysis, and (3) oxidation via the TCA Cycle. All three energy systems are active at any give time, but, the extend to which each is used depends primarily on the intensity of the activity and secondarily on its duration. I will discuss that more in future weeks. 

(Author Note: If you actually read through this and didn’t think “What the heck! I thought this was suppose to be a triathlon blog!” Then congratulations! I wrote this post to provide an overview of the metabolism system your body uses to make fuel while you are at rest, doing your daily activities, and working out. I tried to make this blog post super simplified for non-science people, but it was hard to leave out certain terms. This information is important to at least understand the basics on because it will help you to understand my future posts and nutrition in general. If you have any questions or notice an errors in any of the information please leave me a comment! Enjoy!)

  1. Berg JM, Tymoczko JL, Stryer L. Biochemistry, 6th Ed. New York: W.H. Freeman and Company, 2007.
  2. Da Poian AT, El-Bacha T, Luz MRMP. Nutrient Utilization in Humans: Metabolism Pathways. Nature Education. 2010; 3(9):11. Available at  Accessed May 18, 2012.
  3. Coburn JW, Malek MH. NSCA’s Essentials of Personal Training, 2nd Ed. Champaign, IL: Human Kinetics, 2012