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


Protein Intake for Strength Athletes

~1.33 g/kg per day for Nitrogen Balance


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

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?

michael puglisi, phd, rd sports nutrition. estimation of energy needs

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