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Biomarkers according to sportive phases. A.n asset for effective sports performance management


  • Nitrites (nutrition)

  • pH

  • Ketones

  • Glucose

  • Proteins

  • Albumin

  • Blood

  • Specific Gravity

  • Ascorbic Acid

  • Creatinine

  • Calcium


  • Nitrites (nutrition)

  • pH

  • Ketones

  • Glucose

  • Proteins

  • Albumin

  • Blood

  • Specific Gravity

  • Bilirubin

  • Creatinine

  • Calcium


  • Leukocytes

  • Nitrites 

  • pH

  • Ketones

  • Glucose

  • Albumin

  • Specific Gravity

  • Urobilinogen

  • Ascorbic Acid

  • Calcium


  • Creatinine is a by-product, a metabolite of creatine from animal feed (meat and fish). 

  • It is generated by certain organs such as the pancreas, liver or kidneys. It is transported in our body by the blood, to supply energy to the muscle

  • Creatine consumption helps improve sporting performance. Its increased availability in the body promotes energy renewal during short but intense sports sessions. 

  • To optimiSe the benefits of creatine as a dietary supplement for athletes, it should be taken just before exercise, as well as afterwards. It should be taken in conjunction with a sports session!

  • Beneficial for intermittent, repeated sprinting exercises, such as field hockey and soccer, as well as high-intensity, short-duration sports, such as athletics, resistance sports (bodybuilding, weightlifting): sessions should be short, but intense and repetitive.


  • Nitrates (NO3-) are naturally present in vegetables, and once ingested, are transformed into nitrites (NO2-) by the action of bacteria present in the mouth. 

  • Nitrates converted into nitrites have a vasodilating action, they dilate the arteries, resulting in better irrigation of the muscles during exercise: the muscles consume less oxygen to perform the same effort, and are therefore more efficient.

  • Beneficial for intermittent and repeated sprinting exercises, such as field hockey and soccer, as well as high-intensity, short-duration sports, such as track and field. 

  • N.B: Nitrites are derived from dietary nitrates, which are not transformed in the urinary tract. The presence of nitrites in the urine is therefore (especially when leukocytes are also present) one of the most important signs of a urinary tract infection.


  • pH measures the concentration of H+ ions in urine. It is influenced by diet and medication. The kidney is the main organ responsible for maintaining a normal concentration of hydrogen ions in plasma and extracellular fluid. 

  • Respecting the acid-base balance is one of the functions of sports nutrition, conditioning performance, recovery and injury prevention. Too many sessions one after the other, with no rest day to allow the body to recover and "assimilate" the sessions. 

  • Muscle-builders and endurance athletes are often subject to acid-base imbalance.


  • Ketones are produced by the liver in response to a state of dietary ketosis. This means that the body doesn't have enough glucose to produce energy, so it uses fats instead of carbohydrates (to compensate for the lack of insulin). 

  • Ketone bodies are highly energetic, as they can replace glucose and take over from it once stocks are depleted. They facilitate the use of stored fat, which represents an immense source of energy, very useful for endurance athletes unless they are used to it!

  • Ketone bodies are highly effective in improving fat burning and cognitive performance on low-carbohydrate diets. On the other hand, they have little impact on building strength or improving endurance. However, they can significantly boost energy stores when used in conjunction with a carbohydrate-rich diet, and thus increase endurance in long-duration events.

  • Ketones slow down glucose utilization while preserving muscles and improve recovery, allowing athletes to have more energy and perform longer. Ideal for a final sprint or hill climb at the end of a race after hours of low- and medium-intensity exercise.


  • Glucose comes from 2 carbohydrate sources: fast sugars and slow sugars and is an excellent source of energy.

  • Slow sugars prevent sluggishness and help overcome fatigue after training. Fast sugars are easy for the body to digest, making them an ideal option for rapid recovery. After training, fast sugars quickly replenish your glycogen stores (energy reserves) and help stabilize your blood sugar levels at a normal level.

  • Blood sugar levels often fall during and after exercise: during physical activity, the body uses more glucose and becomes more sensitive to the action of insulin. Regular exercise facilitates the action of insulin. As a result, less insulin is needed when you're exercising. This effect disappears rapidly when you stop training (within a few days).

  • Beware of hypoglycemia after intense, prolonged exercise. It is necessary to check blood sugar levels 1-2 hours after the end of exercise: hypoglycemia can occur up to 6 to 8 hours after the end of exercise.


  • Proteinuria is defined as the excretion of various proteins in the urine. Albumin is the main blood protein. Under normal conditions, it is not excreted in the urine.

  • During intense exercise, small quantities of albumin may pass into the urine. If it is transitory, this phenomenon is not serious. In this case, the athlete is rested for a few days and a urine analysis is carried out to ensure that the albumin leakage was only temporary. A phenomenon illustrating the presence of proteins in urine: DARK URINES IN SPORTS PEOPLE or Pink urine, resulting from increased protein metabolism.

  • High concentration linked to low hydration levels. In this case, it is advisable to drink more before, during and after exercise.

  • The presence of myoglobin in the urine. Myoglobin is a protein found in muscle fibers. Over-exertion in beginner athletes damages these cells, releasing myoglobin into the bloodstream. This is then eliminated in the urine. This phenomenon is often accompanied by fever and severe muscle soreness.

  • Generally, a few days' rest should be enough for urine to return to normal. If this is not the case, further tests should be carried out to determine the cause.


  • It's a protein produced by the liver, but also supplied by certain foods, notably milk and eggs. Albumin is the main transport protein in the blood. It transports small substances that would otherwise be eliminated by the kidneys, including hormones (particularly fat-soluble hormones), bilirubin, calcium and fatty acids. It also ensures the passage of water from the blood to the cells. Blood albumin levels are lowered in cases of malnutrition, liver disease or nephrotic syndrome.

  • High albumin levels are typical during dehydration. It is recommended to analyze serum albumin levels in cases of suspected kidney or liver disease. This analysis can help detect these diseases. The results can also be used to identify a fall or rise in blood albumin levels, which may be due to protein leakage into the urine.

  • Strength athletes need more protein to regenerate muscle tissue broken down during training.

  • Endurance athletes also need to repair their muscle tissue. Several studies have demonstrated the positive effects of increased protein intake on recovery rates


  • Bilirubin (BR) is a product of the liver's metabolism of hemoglobin, which is the molecule that transports oxygen to the red blood cells so that all the cells in your body can be oxygenated.

  • Elevations of BR in the context of athletes are frequent and may be due to:

  • Repetitive strain injury, such as occurs in long-distance races. The mechanism is very simple: microtrauma breaks down the red blood cells, releasing HB into the bloodstream, which metabolizes into bilirubin, appearing elevated in the blood. Liver damage associated with low-intensity endurance sports leads to the presence of bilirubin in the urine. Conversely, short-duration, high-intensity sports reduce the level of bilirubin in the urine.

  • Highly demanding strength training.

  • CrossFit training. 

  • Gilbert's Syndrome: a very common syndrome in young people, in which an asymptomatic rise in BR occurs at times of physical or mental stress, such as a cold, a good workout or a popular race.

  • The presence of bilirubin in urine indicates obstruction of bile flow, or hepatitis, and therefore requires further investigation.

  • No bilirubinuria in hemolysis.


  • Urobilinogen comes from the transformation of bilirubin, a product of the breakdown of hemoglobin in red blood cells. 

  • Urobilinogen is normally eliminated in the stool, after passing through the liver and gallbladder. However, small quantities of urobilinogen are found in normal urine, where they contribute to the specimen's typical yellow color. 

  • Two situations can lead to increased urobilinogen levels in the urine: 

  • liver damage which disrupts the normal passage of urobilinogen through the liver and gallbladder (viral hepatitis, cirrhosis of the liver, obstruction of the gallbladder by a stone, etc.), 

  • or urobilinogen overload due to the release of larger quantities of hemoglobin (destruction of an abnormally high number of red blood cells, as in hemolytic anemia, pernicious anemia, rhabdomyolysis, etc.).


  • Appearing during violent effort or endurance sports, a small blood vessel may bleed, or cells may be destroyed, which may color the urine red/brown. But this does not cause any pain, or even a fever. You just need to be vigilant in the hours and days that follow.

  • Exercise-induced hematuria is a frequent, benign phenomenon that resolves spontaneously in less than a week if exercise is stopped. It generally occurs after intense exercise and disappears at rest in subjects with no underlying renal or urinary pathology. It may be macroscopic (visible to the naked eye) or microscopic (detected only on urinalysis).

  • Repeated impacts on the bladder also cause microtrauma:

  • The lactic acidosis resulting from anaerobic conditions increases the permeability of renal vessels and favours the passage of red blood cells and proteins into the urine.

  • In the event of dehydration, the production of acidic urine during exercise leads to crystal precipitation and irritation of the urinary mucosa.

  • Intense muscular effort in a hot, humid environment leads to a prolonged imbalance between energy supply and demand, inducing rhabdomyolysis (muscle destruction), a phenomenon that is more pronounced in poorly trained individuals. This muscular destruction releases myoglobin, a red-coloured protein which passes into the urine - myoglobinuria.


  • Determining urine specific gravity provides information on the kidney's capacity for concentration and dilution, which is crucial for maintaining hydroelectrolyte balance (homeostasis).

  • Regular hydration helps regulate body heat and compensate for sweat loss during exercise. But "sweat" does not mean "water": when you sweat, you lose not only water, but also minerals such as Sodium, Potassium, Magnesium, Zinc and Copper. This Sodium is necessary because it improves hydration by optimizing cellular exchanges.

  • In the event of prolonged sporting activity, the fluid ingested should not only quench thirst, but ideally also contribute to regeneration.

  • Dehydration and volume overload are health problems frequently encountered by athletes taking part in long-distance endurance events. 

  • There is no clinical decision tool to judge the hydration status of athletes during a long-distance race. 


  • Role in maintaining acid-base homeostasis in athletes.

  • Calcium is particularly important: 

  • For bones: it contributes to good bone health. If food and energy intake are inadequate for sporting activity, bones gradually decalcify, which can lead to overload fractures. 

  • For muscles: Muscle contractility is an essential function for sportsmen and women, since calcium exchanges between muscle cells induce muscle contraction.

  • In sportsmen and women, calcium's role in neuromuscular excitability functions means that, in the event of a deficiency, fatigability during exercise and impaired performance in terms of recovery, coordination and speed can be evoked.

  • If acidity is too high, the body will draw on its only available alkaline reserve: the bones, which may result in a loss of minerals, including calcium. This demineralization can lead to osteoporosis and kidney stones.

  • In the event of dehydration, the production of acid urine during high intensity effort leads to crystal precipitation and irritation of the urinary mucosa.

  • Regular weight training helps maintain bone density by increasing calcium fixation.


  • Vitamin C, also known as ascorbic acid, is an essential vitamin for the human body. Water-soluble, it is naturally present in fruit and vegetables.

  • It plays an essential role in regular sport and bodybuilding. It helps reduce fatigue, promotes recovery after exercise, prevents muscle breakdown and facilitates wound healing.

  • Renowned for its antioxidant and immunostimulant properties, vitamin C is undoubtedly one of the most widely consumed vitamins in the world as a dietary supplement by athletes.

  • However, as the body is unable to manufacture or store it, it is important to consume it regularly to meet nutritional requirements, particularly for athletes and body-builders, as vitamin C is eliminated through perspiration.  Regular physical activity significantly increases the body's need for vitamin C. During exercise, the body produces substances known as free radicals, which are harmful to the organism. As vitamin C is a powerful antioxidant, it helps neutralize the damage caused by free radicals. It is therefore essential to increase your intake accordingly.


  • These are immune system cells, also known as white blood cells, which play a role in fighting infection and certain diseases. 

  • Locally, white blood cells create vasodilatation in the blood vessels, allowing the influx of other cells to reinforce the fight against aggression.

  • During intense sports activities, the presence of leukocytes in the urine may be a sign of physical overtraining, illustrating the existence of an inflammatory phenomenon. Their production is a natural repair phenomenon. Leukocytes detach from their original location to meet the demands of muscles and their inflammation. They are transported to the site of inflammation by the blood, which explains their presence in urine. Sport helps to strengthen the immune system. If physical activity is too intense, the immune system may be weakened. 

  • Acute inflammation: Granulocytes, macrophages (mainly with sprint sports, bacteria...)

  • Chronic inflammation: Lymphocytes (overtraining, viruses...)

  • Women: 4x greater risk of urinary tract infection

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