Sport supplements and young athletes: part 2 – Performance Boosters

Following our first article in this series, which focused on energy-related supplements, this 2nd article focuses on supplements that are deemed to boost performance.


Athletes often take caffeine through the intake of energy drinks, sports drinks or coke before and during training or competition.

Claims: Caffeine will enhance endurance, performance, concentration, motivation and mental alertness and mask fatigue.

Mechanisms: Caffeine is a stimulant. It decreases the perception of effort during exercise and boosts adrenaline levels which increase the levels of fatty acids in the bloodstream. The availability of fatty acids encourages the muscles to use more fatty acids instead of glucose or glycogen (carbohydrate) for fuel. In theory caffeine may help athletes exercise longer and harder.

Side effects: High doses of caffeine can lead to nervousness, an upset stomach, difficulty sleeping, anxiety, rapid heartbeat, dizziness and headaches in some individuals. The amount of caffeine that can lead to these side effects equates to a cup of coffee, two cups of tea or approximately 500 ml caffeinated sports drink.

Caffeine is a diuretic which means that it causes the body to lose water through urination. While studies with adults suggest that regular, moderate caffeine intakes do not dehydrate the body, the effect of caffeinated sports drinks on hydration in young athletes remains unknown.

Safety and effectiveness: The safety and effectiveness of consuming caffeine before and during exercises have yet to be established with children and teenage athletes. Younger athletes may have an increased sensitivity to caffeine and its side-effects which can be worsened by nervousness and anxiousness about the competition. The side-effects outweigh the potential benefits of caffeine for performance.

There are still many unknowns about the effect of caffeine on the performance and health of young athletes. Until more research is done, caffeine cannot be recommended.



Instant coffee


60 mg/cup



100 mg/shot

Filter coffee


120 mg/cup



40 mg/cup

Green tea


40 mg/cup

Sports drink with caffeine


80 mg/500 ml

Energy drinks (eg. Red Bull)


80 mg/250ml



40 mg/330ml

Energy gel


25 mg/sachet

Dark chocolate


40 mg/50g

Milk chocolate


12 mg/50g



Claims: Athletes use creatine mainly for its purported performance-boosting and muscle-building claims.

Mechanisms: Creatine is a protein that is made naturally in the body from amino acids, but can also be found in meat and fish, or taken in higher doses as a supplement. In the body it combines with phosphorus to form phosphorcreatine in the muscle cells, which is an energy-rich compound uses as a fuel source during anaerobic activities such as sprinting, jumping or throwing. Theoretically, creatine may allow athletes to sustain all-out effort longer than usual, recover faster between sets of high-intensity activities and increase muscle mass and strength gains.

Safety and effectiveness: Studies with adult athletes have suggested that creatine supplements can improve performance in high-intensity activities, as well as increase total lean body weight. Unfortunately there is little information about the use of creatine and the health risk in children and adolescents. Performance in children and adolescents tends to be limited by mechanical factors rather than the relative contribution of the aerobic and anaerobic energy systems which will prove creatine ineffective.

There is not enough research to support the use of creatine supplements by children and adolescents and until the safety of creatine can be established in adolescents the, use of this product should be discouraged.



This category includes mainstream fortified nutrition supplements (such as Ensure or Nutren Activ) as well as sports-targeted products (such as EAS Myoplex). They come either as powders designed to be mixed with water or milk, or as long-life ready-to-drink shakes in cartons.

Mechanism: Meal replacement drinks are essentially a mix of protein (usually form milk) and carbohydrate (sugars and/or maltodextrin) with added vitamins and minerals. Sports brands may also contain other ingredients, such as creatine and amino acids that claim to boost performance.

Advantage: Meal replacements supply fairly large amounts of energy, protein, vitamins and minerals in a convenient form to take after training sessions or in between meals.

Tips for using meal replacements:

  • They must be regarded as supplemental to meals, rather than replacers of meals.
  • Athletes with limited appetite may want to consider using meal replacements.
  • Athletes that want to gain weight can consider using meal replacement additional to their food intake.
  • Check the ingredients on the label carefully as some products may contain substances such as creatine, which are not suitable for children and adolescents.

Meal replacements are a safe and convenient way of getting extra energy and nutrients into the diet, particularly for those athletes who have high nutritional requirements.



Protein supplements include protein powders, ready-to-drink protein shakes and protein bars. These products provide a concentrated source of protein and may be based on milk proteins (whey or casein) or soy, or a mixture of these. They contain essential amino acids, used to build body proteins.

Children and adolescents need a little more protein than their non-athletic peers – around 1.2 to 1.4 grams per kilogram of body weight, which can easily be met with food sources. Two or three portions of protein-rich foods daily – chicken, turkey, fish, meat, eggs, lean meat, cheese, milk, yoghurt, beans, lentils and nuts – should fulfill the young athlete’s need. Protein is also found in bread, pasta and breakfast cereals.

Protein supplements are not necessary for young athletes, who should be encouraged to get their protein form a well-planned diet


We continue with our last category of sports supplements next week. These involve more of the natural kind of supplements.

Reference: Anita Bean’s sport nutrition for Young Athletes.(2010)

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