Nutrition for Athletes

Energy Needs

• The need for energy nutrients is high in athletes.
• Glucose is the main source of fuel for muscular activity, and the higher the exercise intensity, the greater the reliance on glucose as a fuel.

Glycogen Storage

• Humans can store about 350 grams (1,400 calories) in the form of muscle glycogen.
• An additional 90 grams (360 calories) in the liver.
• A small amount of circulating glucose in the blood (5 grams, or about 20 calories).
• The larger the muscle mass, the greater the potential glycogen storage but also the greater the potential need.
  

Hormones and Glycogen Storage

• Epinephrine (adrenaline) is a stress hormone
• Cortisol, is also a stress hormone that promotes protein breakdown
• Controlling epinephrine production helps preserve liver glycogen, and controlling cortisol helps preserve muscle protein
  

Low Blood Glucose

• Blood glucose is the primary fuel source for the central nervous system (CNS)
  
• Low blood sugar results in low CNS activity, along with increased irritability and a lower ability to concentrate.
  
• For athletes, low blood sugar may be related to mental tiredness, which is related to muscle fatigue

How Protein Helps An athlete

• Apart from building muscle, proteins help to grow and repair tissue, maintain blood and strengthen the immune system
• Athletes must take enough protein as their requirements could very well be more than normal individuals
• This is a reason why many athletes who do not have a protein rich diet suffer from falling hair and brittle nails
• Female athletes could suffer from amenorrhea (the absence of menstruation) due to the same reason
  
• A diet that lacks protein could be disastrous for the athlete's performance and could cause fatigue/tiredness
  
• Young athletes in the growing up stage need more proteins to fulfill their body needs for growth as well as for the sport they play
  

• Strength athletes need 1.4 to 1.8 grams of protein per kilogram of body weight per day
• Runners and other endurance athletes need 1.2 to 1.4 grams of proteins per kilogram of body weight per day