Key Biological Factors That Affect Your Performance

  • By Paul Moore
  • Published March 9, 2010

By Ben Greenfield

Stop reading, close your eyes, and paint a picture of exactly how many hundreds or thousands of pounds you spend each year on race registrations, clothing, helmets, shoes and various flavours of liquid sugar. Perhaps you spend even more money just to get infinitesimally faster—investing big bucks in new gear and gadgets for just a few extra seconds or watts.

And that’s just the pound investment in getting faster. How about the time investment? How many hours of your week do you spend swimming, cycling, running, lifting, or doing yoga, physical therapy and even calf raises in the shower just to build fitness for your next event?

Now, one final thought experiment. What is the investment of money and time that you put into identifying and improving factors inside your body that may be positively or negatively affecting your training and racing performance? A yearly physical? An occasional cholesterol test? A morning multivitamin?

When you realise that just one percent dehydration can easily add 15 seconds to your next 10K, the importance of achieving an optimum biological status for performance becomes quite apparent. But drinking enough water is just the tip of the iceberg when it comes to optimising key physiological parameters that can give you far more bang for your buck than an electronic shifting system. There are six key internal performance factors that every triathlete needs to know. If these issues are addressed, then the body will be in a state of ideal energy, function and balance. In no particular order, the factors are:

– Optimising vitamin D levels
– Testing and adjusting iron/ferritin levels
– Balancing hormone levels
– Adjusting essential amino acids
– Balancing pH levels
– Fuelling with metabolically specific fuels

These factors are easy to test and easy to fix, but most athletes just don’t know where to start, what tests to ask their doctors for, and what to take to actually optimise the key factors. Here’s the information you need.

There is much conclusive evidence that vitamin D, produced by the body when UV rays strike the skin, is critical to athletic performance. Technically, vitamin D is not really a vitamin but actually a hormone that is made by skin from fat-soluble nutrients in the body. As a hormone, it acts much like testosterone or growth factor, operating directly at the cellular level to encourage tissue growth and repair. Among the numerous studies on vitamin D, one showed that five minutes of UV exposure three times a week improved cardiovascular fitness by 19 percent, while another study that implemented UV lamps showed an improvement in 100-metre dash times from 13.63 to 12.62 seconds. Research has also shown a peak in athletic performance concurrent with a peak in vitamin D blood levels. Perhaps this explains why athletes who leave winter climates to compete in sunny climates do not perform quite as well as those who live in sunny climates year round.

Nearly 75 percent of athletes have less than optimal vitamin D levels—even those living in sunny areas. This is particularly true of individuals with darker skin, such as those of African or Asian descent. Medical recommendations for blood levels of vitamin D often fall below the amount necessary for endurance performance, and I’ve coached individuals who show me their “passed” blood test results with levels of 35-40 ng/mL, only to learn that 50-65 ng/mL is a far better range for athletes. With a combination of regular sun exposure and oral vitamin D3 supplementation, the concentration of vitamin D can easily be restored to performance-enhancing levels.


Most athletes are already familiar with the critical role that iron plays in carrying oxygen from the lungs to the tissues, and know that iron deficiency anaemia reduces one’s ability to deliver adequate oxygen to the muscles to support optimal endurance performance. But most tests for anaemia simply look at a deficiency in red blood cells or haemoglobin, when the reality is that an athlete with low iron levels can actually have neither of these red flags, but still have anaemia-like symptoms.

Typically, an athlete with lower iron levels has a high total blood volume from consistent aerobic training; frequently participates in impact sports such as running, which damages red blood cells; experiences large iron loss from sweating in hot or humid conditions; and has a high-stress lifestyle or inflammatory food intake, either of which can cause stomach bleeding and iron loss. Ferritin, a protein responsible for iron storage, is easily measured with a lab venipuncture test and is the best marker for the body’s iron stores. Recommended ferritin ranges are 50-75ng/mL (higher iron levels can be toxic), but ferritin can easily drop below 25 ng/mL when the risk factors above are combined with a classic endurance athlete diet: high-carbohydrate, low-fat nutrition with limited intake of red meat, leafy greens and legumes.

Two hormones are of prime importance in relation to training stress and recovery: testosterone and cortisol. To understand their role, it is crucial to realise that anabolism is a process of growth and repair, while catabolism is a process of breakdown and destruction. The delicate balance between the body’s anabolic and catabolic states relies upon an ideal ratio of testosterone and cortisol, and a swing toward catabolism results in suboptimal performance and overtraining.

Research shows that after intense competition, testosterone levels temporarily decrease by 50 percent while cortisol levels increase by up to 300 percent. Even though this amplified cortisol response can assist with short-term stress management, regular periods of hard training can easily overwhelm the body with cortisol, causing loss of minerals and bone mass, weakened tendons, decreased amino acid uptake into muscles, and blood sugar imbalances—all symptoms of an overtrained athlete. But unknown to many coaches and athletes, a painless salivary sample (best taken in the morning) can instantly measure the testosterone-to-cortisol ratio, eliminating the hassle of spending an entire training year speculating about whether consistently poor performance could be linked to overtraining.

While testosterone is typically thought of as a male hormone, women’s bodies have it too, albeit in smaller amounts, and all of the information above applies to women as well as men.


Biology 101 tells us that muscles are made from proteins and proteins are made from amino acids. But far beyond reducing the ability to maintain muscle, the lack of just one essential amino acid can severely interfere with the production of key digestive enzymes, neurotransmitters and hormones. In fact, amino acids have more diverse functions than any other nutrient group, including the formation of ligaments, tendons, bones, immune antibodies, enzymes, blood transport proteins, thyroid hormone, growth hormone, melatonin, adrenaline, dopamine, serotonin, skin, hair and nails.

But due to frequent muscle damage and the subsequent need for a higher number of muscle building blocks, about 75 percent of athletes are deficient in at least one essential amino acid. Although there are a total of 22 amino acids, without all eight essential amino acids, the body is unable to make the other amino acids necessary for each of the functions listed above. Meat, fish, poultry and whole eggs are the best examples of foods that provide high levels of the essential amino acids, especially when compared to lower biological value proteins such as whey, soy, beans, nuts and egg whites. Without the optimum combination of whole protein consumption, key digestive enzymes and stomach acids, an athlete will never recover properly. Today, essential amino acids can easily be measured with a finger-stick blood test. Armed with this knowledge, an athlete can make necessary dietary adjustments to protein intake.

The acidity of any solution is measured using a unit called pH. A high-acid substance has a low pH while a low-acid (alkaline) substance has a high pH. Every living organism on the planet relies upon a pH-balanced state, which is why fish die in acidic water and plants may not grow properly in excessively acidic soil. Humans are no different; they rely upon a net alkaline state to function. Inconveniently, breathing, digesting and energy production all create an acidic state, as do low electrolyte intake, sweating, physical stress and the intake of animal proteins, starches, sugar, coffee, tea, soda, juice, milk and energy drinks. Therefore, maintaining crucial alkalinity can be a difficult goal for the athlete.

If grown in mineral-rich soil, fruits, vegetables, nuts and seeds can provide sufficient alkaline materials to buffer the excessive acid produced through high amounts of exercise, and can be even more effective when high-acid food, sugar and caffeine consumption is limited. The best alkaline foods include dark leafy greens, avocados, almonds, coconuts and olive oil. Unfortunately, due to modern agricultural practices such as the use of herbicide and pesticide sprays and commercial fertilisers and overworking of the soil, most grocery store versions of these alkaline foods contains very low levels of the minerals necessary for buffering an acidic state.

The most important of these acid neutralising minerals are calcium and magnesium. Although calcium is generally considered the most important mineral, children and adults in many different countries and food cultures survive on diets significantly lower in calcium than the average American’s but suffer from fewer fractures and lower osteoporosis incidence. Primarily, this phenomenon is related to an improper balance of calcium to magnesium in the typical Western diet—a high calcium intake combined with low magnesium consumption. As one of the most critical elements in the human body and the single most important mineral in sports nutrition, magnesium has taken a back seat to an emphasis on dairy consumption and calcium supplementation. Not only is magnesium crucial to calcium absorption and utilisation, but sleep levels, hydration, metabolic efficiency, oxygen consumption, muscular contractions and heart rate are all critically dependent on adequate magnesium levels.

About 68 percent of Americans do not consume the recommended daily intake of magnesium, and for an athlete who loses magnesium through sweating at a rate much faster than the average person, this important mineral can be severely depleted. I now advise all my coached athletes to have some form of oral or topical magnesium on hand for daily use, and magnesium is quickly becoming recognised as one of the most important performance enhancing supplements, especially for 70.3 and Ironman triathletes. Assessing blood levels of calcium and magnesium is not simple, but a urine analysis of a molecule called NTx can approximate the breakdown of bone, which is well correlated to magnesium/calcium imbalances.

Every athlete has specific nutritional needs based on his or her ancestry and metabolic individuality. Despite the fact that each body retains a “genetic memory” of the foods and nutrients that fuelled ancestors, in the genetic melting pot of today’s society, it can become difficult for an athlete to eat for his or her unique biology. For example, an Inuit can live a long and healthy life fuelled by meat and blubber while a farmer in Asia would be healthier eating rice, vegetables and fish.

In the same way, one athlete can thrive on a high-carbohydrate diet composed primarily of grains and fruits, while another athlete will thrive on red meat, nuts and oils. In the absence of such “metabolically specific fuels,” energy levels may drop, with a subsequent rise in hunger pangs, sweets cravings, post-meal nervousness, irritability and even depression. People generally fall into three categories: fast oxidisers, who perform better on highprotein diets; slow oxidisers, who thrive on high-carbohydrate diets; and mixed oxidisers, who can enjoy the most variety in their food choices. Several comprehensive questionnaires exist that allow an athlete to determine specific food recommendations and ratios, such as at

The off-season is the perfect time to reinvent your body and ensure that your internal performance factors are receiving as much attention as the relatively more expensive and time-consuming external performance factors. Using today’s technology, urine, blood and salivary samples can quickly equip you with everything you need to know to enhance your speed, recovery and health.

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Paul Moore

Paul Moore

Paul Moore is the Online Editor for Triathlete Europe. When not glued to a computer he can be found writing books - most recently Ultra Performance: The Psychology of Endurance Sports and The World's Toughest Endurance Challenges. Both are available on Amazon. Paul has also written Ultimate Triathlon: A complete training guide for long-distance triathletes which is also available on Amazon.