Michael Puglisi, PhD, RD Sports Nutrition. Estimation of Energy Needs.
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Transcript of Michael Puglisi, PhD, RD Sports Nutrition. Estimation of Energy Needs.
Michael Puglisi, PhD, RD
Sports Nutrition
Estimation of Energy Needs
Energy Source with Aerobic Training~50-60% of energy during continuous
exercise at 70% maximal oxygen capacity is derived from carbohydratesRemainder mainly from fatty acid oxidationGreater proportion from fat as intensity ↓
Energy derived from fat ↑ with aerobic training↑ muscle TG utilized for energyPrevents glycogen depletion
Coyle E et al. Am J Physiol. 1997.
Low Energy Intake↓ Muscle Mass↓ Bone densityMenstrual DysfunctionFatigue, Injury, IllnessInability to recover between workouts and
from injuryIf weight loss is the goal, should take place
in the off-season, not during the competitive season
Weight Loss in Competitive SeasonLoss of lean mass→↓ strength and
enduranceImpaired immune, endocrine and
musculoskeletal function↓ Resting Metabolic RatePoor Micronutrient Intake
Iron deficiency a major concern, especially with female athletes
↓ oxygen carrying capacity, critical for endurance athletes
Burke LM et al. J Sports Sci. 2006.
Iron DeficiencyPlasma volume expansion occurs with training
~300 mL for recreational runnersUp to 1L for endurance athletes
↑ Hemolysis with exercise “foot strike” hemolysis for runners
GI BleedingUp to 1/4 of marathoners ↓ visceral blood flow, promoting ischemic
damage↓ LES pressure
Needs estimated to be 70% greater
Zoller and Vogel. Nutrition. 2004.
Carbohydrate IntakeMuscle glycogen stores of a trained athlete
are adequate to fuel exercise up to 60-90 minutes
Fatigue or ↓ work capacity with prolonged continuous exercise or high intensity intermittent exercise of 60 minutes or greaterDepletion of glycogen stores
Carbohydrate for Weight TrainingMuscle glycogen most likely not depleted
Possible with sessions of high intensity lasting longer than an hour
May be an issue for athletes doing cardio and weight lifting
Muscle protein synthesis is maximized with addition of carbohydrate
Carbohydrate LoadingPrevious Protocol
3 days of low carbohydrate diet + trainingDeplete stores
3 days of high carbohydrate diet + tapered training or rest
Current ProtocolFound that 24-36 hours of rest and a high
carbohydrate diet is sufficient to increase muscle glycogen stores
High Carbohydrate Diet8-12 g/kg/dayFor a 70 kg person, 2240-3360 kcal of
carbohydate per day60-70% of kcal as CHO for 5000 kcal dietOkay for an elite athletePretty difficult for casual athlete or someone
who restricts intakeAim for lower end of rangeNot a good idea to overeat just to maximize
glycogen
Overall Carbohydrate Recommendations
Casual Athlete: 50-55% of kcals• 60-70% for 1-2 days before competitionEndurance Athlete
60-65% of intakeProtein will most likely be adequate given
high caloric intake~20% fat
High fat diet will displace necessary carbohydrate
Carbohydrates during exerciseImproves performance for exercise lasting
longer than 90 minutesIntake greater than 1.5g/min lead to oxidation
of exogenous glucose above 1.0g/minAlternative fuel source to muscle glycogen,
preventing depletionRecommendation is 0.7g/kg body weight per
hourShown to improve performance70 kg person: 49g/hr8 oz Gatorade has 14 g carbohydrate~28 oz (3.5 cups) an hour
Jentjens RL et al. Metabolism. 2005.
2
Timing of Carbohydrate Ingestion
TABLE 2 . Total work and physiological responses during, and plasma lactate at the end of, 15-min performance ride following 2 h of exercise at 70+/- 1% [spacing dot above]VO2 peak with ingestion of a sweet placebo throughout exercise (CON), 7% carbohydrate throughout exercise (CHO-7), or a sweet placebo for the first 90 min followed by 21% carbohydrate (CHO-0/21).
McConnell G et al. MSSE. 1996.
Recommendations During ExerciseConsume carbohydrates spaced out every
15-20 minutes6-8% carbohydrate, primarily glucose• More concentrated source or fructose may
slow gastric emptying or cause GI distress~3-4 cups/hr
Postexercise CarbohydratesDelaying carbohydrate intake for 2 hours
after exercise reduces maximal glycogen repletion 24 hours postexercise
Recommendations: 1.0-1.5g/kg carbohydrate every 2 hours for up to 6 hours postexercise70 g person: 70-105 g every 2 hours
Simple if time meal after exerciseNot critical if resting next day and diet
provides adequate carbohydrate
Ivy JL et al. J Appl Physiol. 1988.
Postexercise Carbohydrates Sample 50 gram carbohydrate choices for the foundation
of a meal or snack:
-Wheaties, 2 cups-Nature Valley Granola Bar, 2 packets (4 bars)-Thomas’ Bagel, 1 (3.5 oz)-Banana, 2 medium-Orange juice, 16 ounces-Apple, 2 medium-Raisins, 1/2 cup-Pepperidge Farm multi-grain bread, 2.5 slices-Baked potato, 1 large (6.5 ounces)-Pasta, 1 cup cooked-Rice, 1 cup cooked-Fig Newtons, 5-Flavored Yogurt + 3 graham cracker squares
Carbohydrate Quality?Low GI recovery
diet seemed to increase fat utilization during 90 minute cycling bout at 70% VO2 max
No sparing of glycogen
Needs more research
Stevenson EJ et al. Am J Physiol Endocrinol Metab. 2009.
HydrationLoss of 2% of body weight impairs
performanceWithin 4 hours of exercise: 5-7 ml/kg• 70 kg: ~12-16 ouncesDuring exercise
Sweat rates vary depend on person, weather conditions, and intensity of exercise
0.3-2.4 L/hFluid intake should be adjusted accordingly
Fluid RecommendationsAdjust based on conditionsPlan Ahead! Longer than 60-90 minutes: sodium aids in
fluid retention (sports drinks)Fluid balance is hard during exercise
Sweat rates may be greater than gastric emptying8% carbohydrate or less
Postexercise: 16-24 oz for every pound of weight lostWith food: sodium sources
Tips for PerformanceTest out diets around training
Get used to drinking fluids with longer sessions
Meal timing and types of foods before competition should be tested in training
Plan!Not bringing enough food Delaying consumption prior to next workout
Protein NeedsGenerally met in the typical Western diet• Exceptions may be vegetarians or athletes
who severely restrict their intakeCurrent RDA (0.8 g/kg) is most likely
adequate for most noncompetitive athletes
Protein and Endurance AthletesNitrogen balance studies estimate needs at
1.2-1.4 g/kg per day • ↑ oxidation for fuel with exerciseMain concern is adequate energy intake to
ensure protein sparingWill ensure that other fuels are oxidized,
sparing amino acids for protein synthesis
Phillips SM et al. Int J Sports Nutr Exer Metab. 2007.Tipton KD and Witard OC. Clin Sports Med. 2007.
Protein and Resistance ExerciseExtra protein and energy required for
muscle growthRange from 1.2-1.7g/kg per day
Once again, usually being met, especially in resistance training population
Needs are highest with initiation of training, where most size gain occursTrained individuals more efficient in protein use
Phillips SM et al. Int J Sports Nutr Exer Metab. 2007.
Protein QualityCuthbertson et al. and Phillips et al.
~8.5-10g of EAAs maximally stimulates protein synthesis
Comes out to ~20-25 g of protein sources of high biological value~40% EAAs~20-25 oz milk, 3 ounces meat, fish or poultry, ~4
eggs
Cuthbertson DK et al. FASEB J. 2005.Phillips SM et al. Int J Sports Nutr Exer Metab. 2007.
Protein Synthesis in Response to Exercise
Phillips SM. Nutrition. 2004.
Muscle protein synthesis and breakdown
Phillips SM. Nutrition. 2004.
Protein Intake for Strength Athletes
~1.33 g/kg per day for Nitrogen Balance
Phillips SM. Nutrition. 2004.
Nitrogen BalanceAdequate to assess prevention of
deficiency, but not for maximizing gains with resistance exercise
Positive balance necessary for extra amino acids for muscle growth
Problems with measurementHigher than possible balances with excessive
protein intake Calculation of loss is hard to estimate
Recommendations Based on Research for Strength AthletesProtein intake for strength athletes will
most likely be appropriate when energy needs are met
Adequate energy intake is most often the limiting factor and area that demands more attention for muscle strength gain
Amount of protein in foods
Protein Consumption Around a WorkoutEssential amino acids (EAA) stimulate
muscle protein synthesis 6 g EAA shown to be just as effective as 40
g for muscle protein synthesis stimulation postexerciseNo effect from nonessential amino acids
Copyright ©2000 American Physiological Society
Rasmussen, B. B. et al. J Appl Physiol 88: 386-392 2000
Fig. 6. Muscle protein synthesis as determined by the 3-compartment model
Biochemical Society Transactions www.biochemsoctrans.org Biochem. Soc. Trans. (2007) 35, 1302-1305
Amino Acid InfusionAcutely stimulates muscle protein synthesisStarts to fall back to baseline ~2 hours
after infusionSubstrate needs for synthesis metEnzymes for amino acid oxidation are
upregulated in response to greater circulating concentrations
Bohe J et al. J Physiol. 2001.
Importance of carbohydrateInsulin suppresses protein breakdownAfter resistance training, carbohydrate
alone can reduce muscle protein breakdown
• No effect on muscle protein synthesisCombination of protein and carbohydrate
around exercise would be most beneficialMilk?Amino acids for synthesis, carbohydrate to
stimulate insulin, thus inhibiting breakdown
Borsheim E. et al. J Appl. Physiol. 2004.
Lecker SH et al. J Nutr. 1999.
Ubiquitin PathwayMajor pathway for protein breakdownInsulin reduces Ubiquitin mRNAATP dependent process
↑ by fasting
High Protein IntakeNot shown to detrimentally affect kidney
functionDifficult to link high protein intake with
negative health outcomes Of course it exacerbates existing kidney disease
Does it affect performance?Yes if you are an endurance athlete or
engage in repeated high intensity exercise~8 g/kg Carbohydrate is considered optimal;
tough to reach if overeating protein
Phillips et al. Int J Sports Nutr Exerc Metab. 2007.
Questions?