Sports nutrition

Nutri&onal Perspec&ve

Performance enhancing substances

Overview

•  CHO loading •  Crea&ne supplementa&on •  Colostrum •  Branched-‐chain amino acids •  Caffeine •  Hydra&on considera&ons •  Minerals

Carbohydrate loading

•  Involves changes in training and nutri&on to maximise muscle and liver glycogen stores prior to endurance compe&&on

•  An athlete con&nuously exercising for 90+ minutes would benefit from CHO loading


•  When considering what to eat, the Glycemic index would need to be consulted.

•  CHOs with a low Glycemic index would be most beneficial –  Pasta, rice (see p. 122)

Carbohydrate loading •  It would be impossible to

achieve a proper CHO loading protocol in team sports because of the weekly demand of games and training.

•  Most common sports to CHO load would be: –  Tour cycling –  Marathon –  Triathlon –  Cross-‐country skiing


•  Loading would generally begins 3-‐4 days prior to the event

•  Exercise would taper to ensure more successful loading

•  The day before compe&&on, a rest day is required. CHO loading will be compromised without a rest day


•  Common issues with CHO loading –  Exercise taper is required

–  Some athletes find it hard to lightly train leading up to an event

–  Failure to rest –  Failure to eat enough CHOs (7-‐10g per KG of body weight)

•  You need to cut back on fiber otherwise you may not be able to eat enough –  Too bulky to consume –  Stomach upsets

–  Low fat foods also need to be consumed


•  CHO loading VS. the extra weight

•  In a 70kg athlete, they should put on about 2kg during a loading period.

•  Example CHO loading diet on P.319 -‐ 322

•  Snacks are cri&cal when CHO loading. Why?

Foods to eat 3-‐4 hours before an event

•  Crumpets with honey/jam + flavored milk •  Baked beans on toast •  Breakfast cereal with milk •  Bread roll with meat/cheese/salad •  Pasta with low fat sauce

Foods to eat

One-‐two hours before an event

•  Milk shake/smoothie •  Cereal bars •  Sports bars (low protein) •  Flavored yogurt •  Fruit

Less than one hour before an event

•  Sports drinks •  Cordial •  Lollies

Crea&ne Supplementa&on

•  Used by athletes hoping to increase their strength, power and anaerobic performances

•  The body’s stores of Crea&ne are replenished either by food (beef, tuna, salmon, herring and pork) or supplement

•  You would need to eat 10kg of meat to achieve the same loadings provided by Crea&ne monohydrate supplementa&on

Crea&ne supplementa&on •  Available in capsule,

chewable and powder •  Depending on the

product, 1 tsp contains 5g of Crea&ne monohydrate

•  A ‘fill up’ phase is used to load the muscles with Crea&ne (10-‐20g over 5-‐7 days)

•  This protocol is claimed to increase Crea&ne muscle stores by up to 50%

Crea&ne supplementa&on: Perceived benifits

•  Increased: –  Pre-‐exercise PC stores –  PC resynthesis –  Training intensity –  Short-‐term muscular performance

•  Decreased: –  Dependence on glycogen

–  Lactate

–  Therefore delayed onset of fa&gue

What PC does:

•  Provides the fuel for the rapid resythesis of ADP + pi into ATP

•  An increase in Crea&ne stores in the body will ul&mately lead to an increase in PC store, which increase the ATP PC systems capacity to produce ATP

Possible side effects

•  Increase in body weight (Crea&ne is an osmo&c substance)

•  An increase in water absorp&on can lead to – Muscle cramps –  Dehydra&on problems –  Heat intolerance

–  Proper hydra&on in strongly recommended

•  Other side effects include: –  Seizures, vomi&ng, diarrhoea, anxiety, cardiac arrhythmia and DVT

Ques&ons

•  Are there long-‐term side effects of use?

•  Is the enhanced performance great enough to warrant the expense of the supplement

•  What are the medico-‐legal considera&ons that need to be considered?

Colostrum

•  Some&mes referred to as ‘mothers milk’ because its taken from the mammary glands from a cow.

•  Researchers believe that bovine (cow) colostrum is almost iden&cal the human, and is the only safe form for human consump&on

Colostrum

•  Contains nutrients such as –  Proteins –  CHOs –  Fats –  Vitamins – Minerals –  Bioac&ve growth factors –  Immunoglobulin

Colostrum-‐ benefits

•  Encourages good health during training and compe&&on

•  Immunoglobulin boosts the body’s defense against disease

•  Some effect on muscle &ssue growth (protein synthesis)

Branched-‐chain amino acids

•  Excellent muscle building proper&es

•  Generally used by athletes who use are aker increases in strength, power and anaerobic capacity

•  Delay the onset of fa&gue

Caffeine

•  Big increase in the number of energy drinks consumed

•  Regular caffeine drinks (tea/coffee): 30 – 80mg of caffeine

•  Energy drinks: 100-‐200mg

Caffeine

•  Is absorbed through the stomach and peaks in the blood around 1-‐2 hours aker consump&on

•  Can affect most of the bodies &ssues

Caffeine -‐ benefits

•  Used to s&mulate the CNS and cardiorespiratory system or a diure&c

•  Increases the intensity of muscle contrac&on

•  Can mask the discomfort of physical excursion

•  Can increase fat-‐oxida&on (therefore sparing glycogen stores)

Minerals

•  Many minerals are important electrolytes •  Minerals help control osmosis between body compartments

•  They help maintain the acid/base balance required for normal cellular ac&vi&es

•  Table 14.3 summarises the minerals used to enhance performance

Iron

•  Sources: Red meat, poultry, shelfish, green vegetables.

•  Benefits: Increase O2 carrying capacity, hence aerobic capacity

•  Side effects: Cons&pa&on, upset stomach

Calcium

•  Sources: Dairy, green leafy veggies, white flour, bones of small fish, soya beans

•  Benefits: Prevents calcium deficiencies such as osteoporosis.

•  Side effects: Excess dosage can decrease iron absorp&on

Magnesium

•  Sources: Veggies, fruits, potatoes, unprocessed cereals

•  Benefits: May increase aerobic capacity and vital to enzyme func&on

•  Side effects: Diarrhoea

Potassium

•  Sources: Veggies, fruit/juices, unprocessed cereals

•  Benefits: Reduced BP, facilitates the secre&on of sodium, may prevent cramps, improves nerve transmission

•  Side effects: Toxic effect is very rare.

Sodium

•  Sources: Fish, processed meats, cheese, table salt

•  Benefits: Controls pressures and blood volumes

•  Side effects: Excess results in high BP, stroke, cramps and dehydra&on

Zinc •  Sources: Meats, cereals,

milk, legumes, peas, beans and nuts

•  Benefits: Increases immune system func&on, possibility increased protein synthesis, improves CHO use, vital for muscular growth and repair

•  Side effects: Nausea, can inhibit iron absorp&on causing anemia

Phosphorus

•  Sources: Meat, fish, cereals, dairy, products, green veggies

•  Benefits: Improves aerobic func&on and delays onset of fa&gue

•  Side effects: Long term use can reduce calcium levels.

Glycerol

•  Allows for rapid reten&on of extra fluid

•  Beneficial when undertaking mod-‐high intensity ac&vity in hot/humid condi&ons

•  Typically taken two hours prior to an event/training session

Bicarbonate

•  Increases the body’s ability to dispose of excess hydrogen ions produced during anaerobic glycolysis

•  Acts as a buffer in the muscles reducing the fa&gue effect of a build up of H+

Bicarbonate

•  Taken pre-‐event under the strict supervision of a die&&an

•  Relevant to high intensity ac&vity las&ng between 3 and 7 minutes

•  Poten&al side effects: Gastrointes&nal distress

Sport supplement groupings Group A

•  Defini&on – Products with scien&fic support for enhancement of performance or that support specific nutri&onal goals (recommended by the AIS for its athletes)

– Examples: •  Sports drinks, electrolyte replacement supplements, liquid meal supplements, sports bars and gels, Crea&ne, Glycerol, bicarbonate, caffeine, iron, an&oxidants, glucosamine

Sport supplement groupings Group B

•  Defini&on – Products that are s&ll under inves&ga&on, bit at present – do not have substan&al proof of health or performance benefits (under considera&on by the AIS)

– Examples: •  Probio&cs, Colostrum, Echinacea, Glutamine, Butyrate

Sport supplement groupings Group C

•  Defini&on – Products with no proof of beneficial effects on performance – the majoirty of popular sports supplements belong to this category

– Examples: •  Amino acids (BCAA’s), Ginseng, Gingko biloba, IV vitamin injec&ons, Oral B12, IV iron intake

Sport supplement groupings Group D

•  Defini&on – Products containing banned substances – these are deemed illegal by WADA and must not be used by AIS athletes

– Examples: •  Androstenedione, any testosterone supplement, beta-‐blockers, etc