Diet

A balanced diet is the combination and proportions of…

carbohydrates, fats, proteins, roughage (fibre), water, and essential vitamins and minerals which best provide a sportsperson’s nutritional requirements

Describe energy balance

Energy input = energy expenditure

BMR

Basal metabolic rate, rate at which the body uses energy while at rest to maintain vital functions- such as breathing

How can too much carbs cause weight gain

• excess carbs stored as glycogen

• When glycogen stores are filled, carbohydrates are converted into fatty acids and glycerol

• They are then stored as triglycerides or fat

What is the only way to cause weight loss

Energy intake < energy expenditure

Why an athlete may want to create an energy imbalance

To gain body mass

• sumo wrestler, higher intake than expenditure, helps them gain body fat making it harder for opponent

  To lose body mass

• A jockey would have higher expenditure so they are lighter on the horse to increase speed and chance of winning

Factors that will raise BMR

• eating frequent meals

• exercise

• muscle mass

• age -up to peak physical maturation

• height

• pregnancy

• environment

• smoking/caffeine

Factors that will lower BMR

• age- after peak physical maturation

• fasting/starvation

• sleep

• hormones - thyroxine can lower bmr by 50%

Optimal weight

The weight at which someone should be based on their sex, height, bone structure and muscle girth

Factors affecting optimal weight

• gender

• height

• muscle girth

• bone structure

Hydration

The body’s ability to absorb water

What happens due to the loss of water during exercise

Osmotic pressure raises and the electrolytes become more concentrated in these fluids. Only by replenishing water content, can the electrolytes return to normal concentrations

Sodium ions

helps keep the water and electrolyte balance of the body and needed for ‘action potential’

Potassium ions

regulates fluid balance, muscle contractions and

also for ‘action potential’

Chloride

helps keep the amount of fluid inside and outside

of your cells in balance. It also helps maintain proper blood volume, blood pressure, and PH of your fluids.

Osmolality

The number of particles of solute per kg of solvent.

• Osmolality increases when you are dehydrated and decreases when you have too much fluid in your blood

• Hypotonic

• isotonic

• hypertonic

• Osmolality lower than in blood

• Osmolality same as in blood

• Osmolality higher than in blood

Hypotonic drinks

glucose osmolality of the drink is lower than in blood

• ideal pre exercise

• most beneficial at low intensities

• designed to quickly replace fluids lost through sweating, 1-4% carb content

• fastest glucose benefit for a marathon runner

Isotonic drinks

glucose osmolality same as in blood

• 6-8% carb content

• offers good hydration

• taken up the body as quick as water

• ideal for endurance sports

• aims to quench thirst, provide energy

Hypertonic drinks

Glucose osmolality is greater than in blood

• 10% + carb content

• ideal post exercise

• higher concentration of sugar and salt

• taken up slower than water

• replenishes glycogen stores

• good for recovery immediately after exercise

What is the point of supplementation

• Filling gaps in diet caused by imbalanced diet or inappropriate dietary content

• enhance features of food and drink to improve sports performance

Why are supplements used

• enhance energy stores

• enhance hydration & recovery

• enhance metabolic processes

• delay fatigue

Creatine

Found in skeletal muscle, which is stored as phosphocreatine (PC). Supplementation increases PC levels to enhance ATP-PC system of ATP re-synthesis

Benefits and drawbacks of creatine

Benefits

• replenishes energy stores, increases anaerobic power, improves muscle recovery, delays lactic acid build up

  Drawbacks

• muscle cramps, weight gain, dehydration, stress

Protein shakes

Used to increase total protein content of an athlete’s diet. Athlete’s need more protein than the untrained person to enable muscular hypertrophy and repair muscle following intense training

Benefits and drawbacks of protein powder

Benefits

• helps recovery, helps repair damaged muscle tissue, muscular hypertrophy

  Drawbacks'

• Nausea, headaches, weight gain, liver & kidney damage

Sodium Bicarbonate

Bicarbonate loading is a process whereby a performer ingests bicarbonate prior to competition, which will in turn increase plasma bicarbonate levels that provide additional buffering capacity

Sodium bicarbonate benefits and drawbacks

Benefits'

• delay fatigue, buffers lactate so athlete can train at same intensity for longer, delays onset of OBLA

  Drawbacks'

• cramping, vomiting, bloating, diarrhoea