fih medical seminar, the hague, june 4 2014 dr …...nutritional strategies and hydration before,...
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Nutritional Strategies and Hydration
before, during and after a hockey match
FIH Medical Seminar, The Hague, June 4 2014
Dr Marco Mensink, Wageningen University, Division of Human Nutrition
Field Hockey
skills
tale
nt
Endurance capacity tactics
Power
train
ing
speed anthropometrics
psychological
Sports Nutrition Pyramid
Energy Metabolism
ATP resynthesis
RATE DELAY CAPACITY
Phosphocreatine very high instantaneous very small
(anaerobic) Glycolysis high seconds small
Oxidative metabolism
Glycogen
Blood-borne glucose
Lipids
moderate
low
low
minutes
~ 90 min
> 2 hour
large
small
unlimited
Game player
Football, Soccer, Hockey, Tennis, …
Intermittent exercise
Soccer:
● 1000 bouts of action
● 8-13 km covered
● Jogging (37%), walking, cruising, sprinting (11%)
● ~75% V02 max
● Blood lactate ~4-6; peak 8-12 mmol/L
Intermittent high intensity exercise
With repeated sprints power output supported by PhosphoCreatine and aerobic metabolism
Nutritional Strategies
(Phospho)Creatine
High-energy Phosphate
Contributes to high-intensity exercise for initial seconds, up to 20 sec
Restoration aerobic (O2 availability), within 4-5 minutes
Muscle (95% of body store)
Sources
● Diet (meat; supplements!)
● Endogenous production liver
Carbohydrates
The Main Energy Food
Glycogen
Skeletal Muscle and Liver
Limited amount
Exercise intensity
Anaerobic glycolysis
Oxidative breakdown
Carbohydrates: Diet
Light 3-5 g/kg/day
Moderate exercise 5-7 g/kg/day
Moderate to heavy exercise 7-12 g/kg/day
Extreme exercise 10-12+ g/kg/day
Carbohydrates: (before) Exercise
Pre-event meal GI complaints
Pre-event snack rebound hypoglycaemia
30-75 min Single/multiple CHO -> mouth rinse
1-2 hour Single/multiple CHO -> 30 g/h
2-3 hour Single/multiple CHO -> 60 g/h
> 2.5 hours Glucose:fructose (2:1) -> 90 g/h
Nutritional training essential
Carbohydrates: Recovery
Immediate (0-4h): 1.0-1.2 g/kg/h
Thereafter: ‘daily scheme’
Practical
recommendations
Protein
The Tissue Builder
Protein: optimizing training adaptation
Protein recommendations
.. individuals engaged in regular exercise training require more dietary protein than sedentary individuals.
.. intakes of 1.4 – 2.0 g/kg/day .. is not only safe, but may improve the training adaptations to exercise training.
.. possible .. to obtain .. protein requirements through a varied, regular diet, supplemental protein is a practical way of ensuring adequate intake.
..superiority of one protein type over another .. remains to be convincingly demonstrated.
.. appropriately timed protein intake is an important component of an overall exercise training program.
Protein balance
Optimizing training adaptation
Optimizing training adaptation
Provide sufficient protein with each main meal (20-25 g)
Ingest 20-25 g dietary protein during/immediately after exercise
Whey (dairy) is an excellent source
Consider protein prior to sleep
Co-ingest carbohydrates to replete glycogen
Practical recommendations
Hydration
Hydration status
Fluid balance during exercise
Fluid balance/sweat rate: preBW-postBW+fluid-urine
Practical recommendations
Before Exercise
● Start well-hydrated
● Pay attention to thirst
● Drink last 2 hours 5-10 ml per kg -> pale yellow urine
● Hyperhydrate
During Exercise
● Short-term: drink to sweat loss
● Long-term: drink to thirst or prevent > 2-3% BW loss
● Cold drinks (thermoregultaion)
● ‘overdrinking’ (hyponatremia)
Beverage composition
Sodium
● Decreases diuresis (urine output)
● Stimulates thirst
Carbohydrates
● Sodium-glucose co-transport
● Gastric emptying
● Glycogen restoration
Palatability
Issues in post-exercise rehydration
Practical issues: opportunities, conscious decisions
Voluntary intake: 30-70% of sweat losses
People fail to rehydrate
Difficult after high levels of hypohydration (2-5% BM) or interval between exercises short (6-8h)
Solid foods
Practical recommendations
After Exercise
● 150% of sweat loss
● add to your liquid:
● Sodium and Glucose
● Slower drinking (GI complaints)
● Palatable is key
● Limit alcohol intake
● Solid foods / sodium replacement
Summary
Carbohydrates: the Energy Food
● Daily diet
● Pre/during/post exercise
Protein: The Muscle Builder
● 20-25 gram per meal and post exercise
Rehydration:
● 150% sweat loss
● Sodium content
Recovery meal/drink
Repletion: Carbohydrates -> 1-1.5 g/kg
Rehydration: Fluid
Reparation: Protein -> 10-20 gram
