Samenvatting Nutrition and Sports

Nutrition and Sports | lectures
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Sport specific
nutrition


Balanced diet


Cycle of sports sciences

Importance of sports nutrition: good food choices will not make a mediocre athlete into a champion, but poor
food choices may prevent the potential champion from realising his/her potential

Balanced diet Sport-specific nutrition Supplements
To support healthy & active To optimize performance and Final winning edge
lifestyle recovery  To supplement your diet
 Sufficient energy intake  Macronutrients/fluid → should never be main focus
 Adequate macronutrients  Timing of nutrient intake  Be critical, backed-up by science
 Sufficient fluid intake  Discuss with experts
 Adequate micronutrients  Normal foods → would this work for me?
→ varied diet  Sport nutrition products

Types of athletes
 Explosive power weightlifter
 Phosphagen system sprinter
 Anaerobic middle-distance
 Aerobic capacity endurance athlete
 Multiple sprints gameplayer




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,It is hard to measure performance
 Validity accuracy
 Resembles performance that is stimulated
 Correlation, prediction
 Reliability precision
 Correlation
 Sensitivity
 To detect small but important differences

Endurance performance: time to complete a certain task
Endurance capacity: exercise time to volitional fatigue

External factors to control when doing performance testing
 Familiarization
 Verbal encouragement
 Music
 Feedback
 Additional measurements
 Diet
 Exercise

Dietary standardization Exercise standardization
 Provide standardized meals  Training status of subjects
 Measure intake of nutrients during study  Habitual training
 Report dietary intake (compliance)  Last exercise bout
 Choose between measuring relative or absolute
exercise intensity




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,Energy metabolism I & II

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+¿+energy (31 )¿
mol
ATP+ H 2 O → ADP+ P i+ H
ATPase




Sources of energy
 ATP breakdown Phosphagen system
 Phosphocreatine (PCr) → creatine + Pi
 Anaerobic glycolysis glucose-6-P → lactate Substrate-level phosphorylation
 Oxidative phosphorylation CHO, fat, proteins, alcohol

ATP re-synthesis
Rate Capacity
Delay
(mol/min) (mol)
Phosphocreatine 4.4 Instantly 0.67
Anaerobic glycolysis 2.3 5-10 s 1.6
Oxidative metabolism
Glycogen ~1.0 Minutes 84
Blood-borne glucose 0.34 ~90 min 19
Lipids 0.40 > 2 hours* 4000
* Lipid oxidation for ATP re-synthesis starts instantly when starting exercise, but lipid metabolism only 100%
active after 2 hours




1 Relative contribution of energy systems 2 Absolute contribution of energy systems;
total ATP resynthesis speed declines; decreased performance



ATP breakdown hydrolysis of the ATP that is stored in the body


Phosphocreatine breakdown
 Activation: ratio ATP/ADP ↓ because of ATP breakdown
 Inhibition: ratio ATP/ADP ↑ because of aerobic ATP
production ↑ or ATP utilization ↓
 Recovery within 4 minutes after exercise, all PCr restored
 Oxygen dependent!

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, Glycolysis (anaerobic; O2 independent pathway)
 Glycogenolysis glycogen as substrate yields 3 ATP (50% more!)
 Glycolysis glucose as substrate yield 2 ATP
 Acetyl-CoA goes into citric acid cycle (TCA-cycle); aerobic metabolism
 When oxygen is limited; pyruvic acid → lactic acid
 Maximum not reached until after 5 seconds
 Maintained up to 30 seconds
 Rate lower (2x), but size higher (4x) compared to PCr lower power
output
 Goals of glycolysis
 ATP synthesis
 NAD regeneration (H+ carrier); to keep glycolysis running
 Phosphofructokinase (PFK)
 Inhibited by: ATP ↑ , PCr ↑ , citrate ↑
→ accumulation of glucose-6-P → inhibits hexokinase
 Stimulated by: ADP ↑, AMP ↑, fructose-6-P ↑




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