Diet and nutrition and their effect on physical activity and performance

Carbohydrates

• principle source of energy used by the body

• the main fuel for high intensity or anaerobic work

• Carbohydrate in food is digested and converted into glucose and enters the bloodstream

• The glucose is stores in the muscles and liver as glycogen

• stores are limited so regular refuelling is necessary.

What are the two types of carbohydrates?

• simple carbohydrates

• Complex carbohydrates

What are simple carbohydrates?

• The quickest source of energy

• easily digested by the body

• found in fruits, processed foods, anything with refined sugar added

What are complex carbohydrates?

• found in nearly all plant-based foods

• usually take longer for the body to digest

• most commonly found in bread, pasta, rice and vegetables.

What are the different types of fats? And what do they all carry?

• saturated fats

• Cholesterol

• Trans-fats

• Unsaturated fats

  They all carry fat soluble vitamins, ADEK

Saturated fats

• Found in both sweet and savoury foods most come from animal sources

• Too much saturated fat leads to excessive weight gain, which will reduce stamina, limit flexibility and lead to health problems such as CHD, atherosclerosis, diabetes and high blood pressure.

Cholesterol

• Type of fat found in the blood

• Too much saturated fat needs to high cholesterol levels

• Cholesterol is made predominantly in the liver and is carried by the blood as LDL and HDL

• Too much LDL can’t lead to fatty deposits developing in the arteries which can have a negative effect on blood flow

• HDL takes cholesterol away from the part of the body where it has accumulated to the liver where it disposed of.

Trans-fats

• Artificial hydrogenated fats

• found in meat and dairy products

• Most are made from an industrial process that allows food to have a longer shelf life

• They can lead to high levels of blood cholesterol, heart disease and diabetes.

Unsaturated fats

• A major source of energy in the body

• Used for low intensity aerobic work (jogging)

• can’t be used for high intensity exercise where oxygen is in limited supply as they require oxygen to be broken down

What are fats an energy source for?

• Long-duration

• low-intensity exercise

Proteins

• Combination of many chemicals called amino acids

• important for muscle growth and repair and to make enzymes, hormones, and haemoglobin

• minor source of energy and tend to be used more by power athletes, who have a greater need to repair and develop muscle tissue.

Vitamins

• keep an individual healthy with a good immune system

• allows a performer to train maximally and recover quickly.

vitamin C

Source – green vegetables and fruit

• protect cells and keep them healthy

• Required for the breakdown of carnitine, which is a molecule essential for the transport of fatty acids into the mitochondria

• Helps in the maintenance of bones, teeth gums and connective tissue such as ligaments

Vitamin D

Source - our body under the skin when it is exposed to sunlight, can also come from oily fish and dairy produce

• Has a role in the absorption of calcium which keeps bones and teeth healthy

• Helps with phosphocreatine recovery in the mitochondria

Vitamin B1 (thiamin)

Source - yeast, egg, liver, wholegrain bread, nuts, bread, meat, and cereals

• works with other B group vitamins to help breakdown and release energy from food

• Keeps the nervous system healthy

Vitamin B2 (riboflavin)

Source - dairy products, liver, vegetables, eggs, cereals, and fruit

• Works with other B group vitamins to help breakdown and release energy from food

• Keeps the skin eyes and nervous system healthy

Vitamin B6

Source - meat, fish, eggs, bread, vegetables, and cereals

• Makes red blood cells and keeps the nervous system healthy

• Releases energy from food

What are the minerals?

• calcium

• Sodium

• Iron

calcium

• Needed for strong bones and teeth

• necessary for efficient nerve and muscle contraction which is important during an exercise

sodium

• Helps regulate fluid levels in the body

• too much sodium is linked to an increase in blood pressure which can increase the risk of a stroke or heart attack

iron

• Involved in the formation of haemoglobin in red blood cells, which helps transport oxygen and therefore improve stamina

• lack of iron can lead to amenia.

Fibre

• Source - wholemeal bread and pasta, potatoes, nuts, seeds, fruit, vegetables, and pulses

• Important during exercise as it can slow down the time it takes the body to breakdown food

• results in a slower more sustained release of energy

• Dietary fibre causes bulb in the small intestine, helping to prevent constipation and aiding digestion

Water

• Makes up 60% of a persons body weight

• essential for good health

• it transports nutrients hormones and waste products around the body

• regulates body temperature - when you take part in exercise, energy is required and some of that energy is released as heat. Water will help you from overheating

• The evaporation of sweat helps to cool you down, but this means water is lost during the cooling down process. A lack of water pre-during or post exercise can cause dehydration.

What is dehydration?

• Occurs when the body is losing more fluid than it is taking in.

What does dehydration result in?

• Increase in blood viscosity reducing blood flow to working muscles and the skin

• Reduce sweating to prevent water loss which results in an increase in core temperature

• Muscle fatigue and headaches

• Reduction in the exchange of waste products/transportation of nutrients

• Increased heart rate resulting in a lower cardiac output

• Decrease performance/ reaction time/ decision-making

What is glycogen loading?

• A form of dietary manipulation to increase glycogen stores over and above that which can normally be stored (supercompensation)

• An increase in water intake will also aid glycogen storage

• used by endurance performers.

Method one for glycogen loading

• Six days before competition performer eat a diet high in protein for three days and exercise at relatively high intensity to burn off any existing carbohydrate stores

• followed by three days of a diet high in carbohydrates and some light training

• by totally depleting glycogen stores they can then be increased by up to 2 times the original amount (supercompensation) and can prevent a performer from hitting the wall.

Method two for glycogen loading

• day before competition three minutes of high intensity exercise opens a carbon window

• Replenishing glycogen stores during the first 20 minute window after exercise can enhance performance the next day

• In the 20 minutes immediately after exercise the body is most able to restore lost glycogen the carbo window closes after two hours.

method three of glycogen loading

• Non-depletion protocol

• training intensity is reduced the week before competition

• three days before competition a high carbohydrate diet is followed with light intensity exercise.

positive effects of glycogen loading

• Increased glycogen storage

• Increased glycogen stores in the muscle

• Delays fatigue

• Increases endurance capacity

Negative effects of glycogen loading

During carbo-loading phase

• water retention which results in bloating

• heavy legs

• Problems with digestion

• Weight increase

During the depletion phase

• Irritability

• Need to alter the training program through lack of energy

Creatine monohydrate

• supplement used to increase the amount of phosphocreatine stored in the muscles

• Phosphocreatine is used to view the ATP PC system which provides energy

• Increasing the amount of creatine in the muscles will allow this energy system to last longer

• can also help improve recovery times

• Athletes in explosive events such as sprint jumps and throws are likely to experience the more benefits as they can perform at higher intensity for longer.

Positive effects of taking creatine monohydrate

• Aims to provide ATP

• Replenishes phosphocreatine stores

• Allows the ATP-PC system to last longer

• Improves muscle mass

Negative effects of taking creatine monohydrate

• possible side-effects, including muscle cramps, diarrhoea, water retention, bloating, and vomiting

• Hinder aerobic performance

• Mixed evidence to show benefits

Sodium bicarbonate

• an antacid

• can increase the buffering capacity of the blood so it can neutralise the negative effects of lactic acid and hydrogen ions that are produced in the muscles during high intensity exercise.

• It reduces the acidity within the muscle cells in order to deliver fatigue and allows the performer to continue exercise at a very high intensity for longer.

Define buffering

• The ability of the blood to compensate for the buildup of lactic acid or hydrogen ions to maintain the pH level

Define lactic acid

• A byproduct of anaerobic respiration

• As it accumulate it causes fatigue

Define hydrogen ions

• Responsible for the acidity of the blood

Positive effects of taking sodium bicarbonate

• reduces acidity in the muscle cells

• Delays fatigue

• Increases the buffering capacity of the blood

Negative effects of taking sodium bicarbonate

• possible side-effects, including vomiting, pain, cramping, diarrhoea, and feeling bloated

Caffeine

• naturally occurring stimulant which can increase mental alertness and reduce fatigue

• improve the mobilisation of fatty acids in the body thereby sparing muscle glycogen stores

• used by endurance performers who predominantly rely on the aerobic system

• found in coffee, tea and caffeinated gels.

Positive effects of caffeine.

• it is a stimulant/ increases mental alertness

• Reduces effects of fatigue

• Allows fats to be used as energy source/delays use of glycogen stores

• Improve decision-making/reaction time

• May benefit aerobic performance/endurance athletes

Negative effects of caffeine

• loss of fine control

• Against rules in most sports when consumed in large quantities

• Possible side-effects, include dehydration, insomnia, muscle cramps, stomach cramps, vomiting, irregular heartbeat, and diarrhoea