A brief overview of Macronutrients, Miconutrients and Hydration.
Foods
The three main sources of energy come from Carbohydrates, Protein and Fats which are all called Macronutrients.
The energy per gram from these sources are:
- Fats 37 kilojoules per gram (9 calories)
- Proteins 17 kilojoules per gram (4 calories)
- Carbohydrates 16 kilojoules per gram (4 calories)
During times of high energy/activity to maintain weight, replenish glycogen (energy) stores and to provide adequate protein to build and repair tissues marconutrients such as carbohydrates and protein are required. Essential fatty acids and fat soluble vitamins should be maintained at a sufficient level to also help maintain body weight.
Food should be consumed before, during and after exercise to help maintain blood glucose concentration levels to maximise exercise performance and improve recovery times.
Supplementation has not been shown to improve overall performance in athletes who are well nourished and have a well balanced diet. They benefit those athletes who do not have a well balanced diet or those who utilise severe weight loss practices as a part of their training (ie. jockey's, boxers). These benefits also crosses over to sedentary individuals who do not have a balanced diet.
Minerals and Trace Elements (Micronutrients)
Trace elements and minerals generally include calcium, iron, magnesium, selenium, chromium, phosphates, copper and zinc. Research shows these are important for muscle contraction, normal heart rhythm, nerve impulse conduction, oxygen transportation, enzyme activation, immune function, anti-oxidant activation, bone health and acid/base balance.
Iron and calcium are traditionally the minerals deficient in people who have a low micronutrient diet.
The minerals of most importance include:
Calcium-plays a role in muscle contraction, levels may drop during high intensive training and this can predispose to osteoporosis, especially in female athletes. The body has high levels of calcium stores (bone), which is where the body will leach calcium from if levels in the blood fall, this then leads to a decrease in bone mineral density (osteoporosis).
RDI-1000-1200 mg/day
Food Sources: tofu, sardines, milk, cheese, dark green vegetables
Phosphates-are required for energy production (ATP) and red blood cell (RBC) production. Studies have showed phosphate salt supplementation may positively influence oxygen release from haemoglobin (substance which holds oxygen in RBC) therefore improving aerobic endurance exercise performance.
RDI-800mg
Food Sources: cheese, fish, milk, beef, eggs, legumes, nuts, seeds
Magnesium-plays a role in regulation of muscle contraction, oxygen delivery and protein synthesis (muscle, ligament growth/repair). It may improve strength and cardiorespiratory function.
RDI-310-420 mg
Food Sources: soy flour, fortified cereal, lentils, spinach, walnuts, peanuts, almonds, seafood
Iron-is one of the most important minerals in the body as it is involved with haemoglobin, myoglobin (delivers oxygen into the muscle) and activation of enzymes in muscles cells, all of which are involved with the transportation and metabolism of oxygen for aerobic energy production during endurance exercise.
- Iron deficiency anaemia is common among athletes and is actually more prevalent in athletes than in normal healthy sedentary individuals. This deficiency ultimately impairs muscular performance, primarily due to a lack of oxygenation to the muscles.
- Because of it is effect on oxygen transportation and deliver to the muscles athletes like Lance Armstrong have used iron supplementation to boost oxygen deliver and improve their endurance performance. This is only of benefit though when RBC and haemoglobin levels are increased (ie. altitude training). If RBC and haemoglobin levels are normal, additional iron levels (supplementation) will not improve performance.
RDI-10mg
Food Sources: liver, beef, lamb, pork, fortified cereal, nuts, beans
Zinc-is involved with muscle energy and protein synthesis. Diets high in carbohydrates and low in protein and fats can lead to a zinc deficiency with loss of body weight, fatigue and reduce endurance. The research on zinc supplementation to improve athletic performance is limited.
RDI-60mg/day
Food Sources: oysters, liver, beef, poultry, seafood, diary products, eggs, oatmeal corn, lentils
Chromium-is involved with insulin (insulin lowers blood glucose levels) and there is some (limited) research supporting chromium supplementation to increase lean muscle body mass and reduce body fat.
RDI-50-200 mcg
Food Sources: raw oysters, peanuts, wine, mushrooms, apples
Selenium-supplementation provides no additional performance gains
RDI-2.5mg
Food Sources: oatmeal, soy flour, wheat gem, rice bran, peanuts, mussels, bananas
Supplementation in those on a low micronutrient diet or on a strict specific diet, athletes or lay people, may improve peoples day-to-day well-being and performance.
Sources:
Rodriguez NR, Di Marco NM, Langley S, "American College of Sports Medicine position stand. Nutrition and Athletic Performance", Journal of Medicine and Science in Sport and Exercise, 2009, March, pages 709-31
Sawka MN, et.al, "American College of Sports Medicine position stand. Exercise and Fluid Replacement, Journal of Medicine and Science in Sport and Exercise, 2007, February, pages 377-90
Williams MH, "Dietary Supplements and Sports Performance: Minerals", Journal of the International Society of Sports Nutrition, 2005, June, pages 43-49
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