Summary: Nutrition and Sports
Introduction 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
Introduction 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
