Samenvatting
Summary Nutrition and Sports (HNH36806)
Summary of the course Nutrition and Sports (HNH36806) lectures with highlighted terms and illustrations.
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Summary: Nutrition and SportsIntroduction to sports nutrition
Describe some specific issues in sports nutrition (research), like the nutrition pyramid, aspects of assessing
performance and new perspectives.
• Sports nutrition → application of nutrition principles for the purpose of improving training, recovery and
performance
• ‘Customised nutrition’ → eating strategies for athletes must take account of each athlete's physiological
and biochemical characteristics as well as the training load and competition goals
• ‘Periodized nutrition’ → sports nutrition is now more about using nutrition strategies to modulate training-
induced muscle adaptations
• Speed, strength (power), coordination, flexibility and endurance are determinants of performance
o Measuring strength (power) → one repetition maximum (e.g. leg press)
o Measuring endurance → time trial (as much work as possible within a time frame)
• Validity, reliability and sensitivity of measures of sporting performance
o Validity → accuracy; resembles the performance that is simulated
o Reliability → precision
o Sensitivity → detect small but important differences
• External factors need to be controlled when doing performance testing
o Familiarisation → always first familiarise with the test method before baseline measurement to
prevent learning effect from influencing results
o Diet standardisation → diet on test day or day before (provide, measure and report)
o Exercise standardisation → training status, habitual training, last exercise bout and experimental
exercise intensity (relative vs. absolute)
• The sport nutrition pyramid consists out of a balanced diet, sport
specific nutrition and supplements
o Balanced diet → healthy and active lifestyle Supplements
▪ Sufficient energy intake
▪ Adequate macro- and micronutrients
Sport specific
▪ Sufficient fluid intake nutrition
o Sport specific nutrition → optimize performance and recovery
▪ Macronutrients/fluid to meet training/competition goals
▪ Timing of nutrient intake Balanced diet
o Supplements → final winning edge
▪ Ergogenic supplements
Energy metabolism
Describe the metabolic pathways of energy expenditure during exercise and apply this to different types of athletes
• As only a small amount of ATP is stored in the body, it needs to be resynthesized from:
o Phosphocreatine (PCr) → high rate (mol/min), no delay, low
capacity (mol)
o Anaerobic glycolysis → medium rate, small delay (5-10 s),
medium capacity
o Oxidative metabolism → low rate, big delay (minutes
(glycogen) to hours (lipids)), high capacity
• The energy metabolism is regulated by hormones, substrate
availability and local factors
o Hormones → e.g. adrenalinꜛ, insulinꜜ, glucagonꜛ and cortisolꜛ
o Substrate availability → e.g. muscle glycogen
o Local factors → e.g. ATP/ADP ratio, Ca2+ and H+
• Metabolic pathway weightlifter → explosive power
o Uses ATP stores
• Metabolic pathway sprinter → mainly anaerobic metabolism
o Phosphagen system → ATP and phosphocreatine breakdown
▪ Phosphocreatine breakdown into creatine → ATP
• Activated by a decrease in ATP/ADP ratio
• Complete resynthesis within 4 minutes
• Recovery inhibited by a lack of oxygen
o Glycolytic system → ATP resynthesis from glycogen metabolism
▪ Glycogenolysis → breakdown of glycogen
▪ Glycolysis → conversion of glucose to pyruvic acid
▪ Rate lower (2x) and size higher (4x) than PCr → lower power output
o Performance depends on maximum speed achieved early in exercise → PCr availability
▪ Maintenance of force is pH dependent (H+ and lactate) → acidification/fatigue
after +/- 20 sec
o Supplementation of creatine can lead to higher PCr levels
▪ Downside → weight gain (water) due to osmotic effect
, • Metabolic pathway middle-distance athlete → both aerobic and anaerobic
metabolism
o Glycolytic system → ATP resynthesis from glycogen and blood
glucose
▪ Glycogen → 4 – 1 = 3 ATP
▪ Blood glucose → 4 – 2 = 2 ATP
▪ Glycogen phosphorylase → stimulated by adrenalin
and Ca2+ & inhibited by H+
▪ PFK → stimulated by F-6-P and ADP and inhibited by
ATP/PCr and H+
▪ NAD regeneration (from NADH) is a crucial step to keep
a high glycolysis rate
o Recovery takes longer than for sprinters
▪ ATP/PCr → few minutes
▪ Removal lactate (restore pH) takes longer
▪ Recovery muscle glycogen → at least 24h
o Fatigue is caused by a pH drop in the muscle (lactate)
▪ Buffer systems → carnosine in muscle and HCO3- in blood
▪ pH drop has an influence on muscle contraction, causes
pain and slows down glycolysis
• Metabolic pathway endurance athlete → mainly aerobic metabolism
o Aerobic power/capacity is determined by the maximal oxygen
uptake (VO2max) and fractional utilisation (% VO2max)
▪ VO2max = Q x (a-v)O2
• Q = cardiac output
• (a-v)O2 = arteriovenous oxygen difference
o Carbohydrate oxidation (CHO oxidation)
▪ Pyruvate dehydrogenase (PDH) → pyruvate to
acetyl-CoA
• Rate limiting for CHO oxidation
▪ Balance between aerobic (oxidative
phosphorylation) and anaerobic metabolism
(substrate phosphorylation)
o Fat oxidation → β-oxidation
▪ Limited by carrier (CPT-1) into mitochondria
▪ Stimulation lipolysis by (nor)adrenaline, glucagon,
growth hormone and cortisol
▪ Inhibition lipolysis by lactate accumulation and
insulin (CHO intake)
▪ Lower rate than CHO oxidation
o Factors influencing substrate utilisation are substrate availability, oxygen availability, previous
exercise and diet, type, intensity and duration of exercise, drugs and levels of plasma hormones
o Fatigue (‘hitting the wall’) can be caused by:
▪ Muscle glycogen depletion → fat oxidation can only meet energy for 50-60% VO2max
▪ Hepatic glycogen depletion → hypoglycaemia
• Metabolic pathway game player → intermittent high intensity
exercise (sprinting)
o Repeated sprints → relative contribution PCr and aerobic
metabolism increases and contribution anaerobic
glycolysis rapidly decreases
▪ As muscle glycogen stores run out
▪ PCr can be recovered within 4 min
o Fatigue is caused by insufficient recovery time, muscle
glycogen depletion and lactate accumulation
• The energy requirement of athletes can be calculated:
o Energy requirement (ER) = general EEhours beside exercise + total
EE exercise
▪ General EEhours beside exercise = (BMR x PAL) x h/24
• BMR → Basic Metabolic Rate
• PAL → Physical Activity Level
▪ Total EEhours exercise = (MET x BW) x h
• MET → Metabolic Equivalent of Task
o Ratio of work MR to a standard RMR
(Resting Metabolic Rate) of 1
o Moderate intensity → MET 3-6
• Energy balance → amount of dietary energy added to or lost from the body energy stores after the body’s
physiological systems have completed their work for the day
o Energy Balance (EB) = Energy Intake (EI) – Total Energy Expenditure (TEE)
o Not best concept as body adapts when TEE is higher than EI by lowering the BMR
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