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Short-term High Fat Diet Prior to Carbohydrate Loading: Gender Differences on Perceived Performance and Time to Fatigue. Alaine Mills KINS 6130 November 16, 2010. Introduction. Fuel Sources during Endurance Exercise Carbohydrates and Fats Most important to ensure optimal performance - PowerPoint PPT Presentation
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Short-term High Fat Diet Prior Short-term High Fat Diet Prior to Carbohydrate Loading: to Carbohydrate Loading: Gender Differences on Gender Differences on Perceived Performance and Perceived Performance and Time to Fatigue Time to Fatigue
Alaine MillsKINS 6130November 16, 2010
Introduction Introduction Fuel Sources during Endurance
Exercise◦Carbohydrates and Fats
Most important to ensure optimal performance
◦Protein Plays a small energetic role during
endurance activities
The Importance of The Importance of Carbohydrates for Endurance Carbohydrates for Endurance AthletesAthletesPlay a role in the rapid metabolizing of
fats for energyIf liver & muscles are depleted of
glycogen, athlete will experience extreme fatigue ◦“Hitting the wall”
Carbohydrate stores are limited◦ Needs increase for endurance exercise(Sedlock, 2008)
The Importance of The Importance of Carbohydrates for Endurance Carbohydrates for Endurance AthletesAthletesThe CNS relies on carbohydrates
to function properly◦Mental fatigue
The time to exhaustion during endurance◦directly related to the initial levels of
stored muscle glycogen(Sedlock, 2008)
The Importance of Fats for The Importance of Fats for Endurance Athletes Endurance Athletes Fat becomes a primary source of
energyEndurance training improves the
body's ability to utilize fats for energy◦Able to mobilize fats from adipocytes
making more fatty acids available to working muscle
Endurance training also improves the working muscle’s capacity to oxidize fats that are delivered
(Sedlock, 2008)
Carbohydrate Loading Carbohydrate Loading Manipulating one’s diet to
enhance performance◦High carbohydrate diet several days
prior to competition
Maximizing muscle glycogen levels before an exercise event to help prevent fatigue (Sedlock, 2008)
Literature ReviewLiterature ReviewResearch on short term high fat
diets prior to CHO loading (Lambert, 2001; Havemann, 2006; Burke, 2000)
Results:◦Modified patterns of fuel substrate
utilization◦Enhanced subsequent exercise capacity ◦Maximized the capacity for fat oxidation
Increased reliance on fat Decreased reliance on muscle glycogen
Literature ReviewLiterature Review
Women oxidize more lipids during exercise than men (Tarnopolsky, 1993; Devries, 2006).
◦ Lower RER◦ Greater Reliance on fat oxidation ◦ Due to Estrogen?
Some studies done on carbohydrate loading showed no effects on women (Tarnopolsky, 2001).
Literature ReviewLiterature Review
Gaps in Previous Research on High Fat Diets: ◦Primarily male subjects only (Lambert,
2001; Havemann, 2006; Burke, 2000)
◦Lack of female-male comparison◦Primarily Cycling (Lambert, 1994; Goedecke,
1999; Van Zyl, 1996)
PurposePurposeTherefore, the purpose of this
study is to compare male and female endurance runners on perceived performance and time to fatigue after following a short-term high fat diet prior to carbohydrate loading.
Research Hypotheses Research Hypotheses Women will increase their time to
fatigue significantly more than men.
Women will decrease their RPE score significantly more than men.
LimitationsLimitationsConvenience Sampling
◦Volunteers No randomization Internal & External Validity
AssumptionsAssumptionsParticipants will not deviate from
the assigned diet planParticipants will give maximal
effort throughout the study
Participants Participants Convenience Sample
◦20 volunteers who run 3 days per week Average 30 minutes per session
◦Ages: 19-24 years old College students
◦Grouped according to gender◦Recruitment ◦Informed consent
Preliminary TestingPreliminary Testing◦Anthropometric Data
Height & Weight
◦Body Fat Percentage BIA
Reliable (r= 0.95-0.987) Criterion-Related Validity(Jackson,1988)
Preliminary Testing Preliminary Testing VO² Max Test
Modified Bruce Treadmill TestProvides warm-upTreadmill speed increases in speed and
grade every 3 minutes. Stage Speed (mph) Grade (%) Duration (min)
0 1.7 0 3
.50 1.7 5 3
1 1.7 10 3
2 2.5 12 3
3 3.4 14 3
4 4.2 16 3
5 5.0 18 3
6 5.5 20 3
7 6.0 22 3
Preliminary TestingPreliminary TestingBruce Treadmill Test
◦Stability Reliability r=0.96
◦Criterion-Related Validity Expected relationships verified
(Robinson,2001)
Gender and Age Equation Activity Factor
18-30 year old Males (15.3 X BW) + 679 1.6-2.4
18-30 year old Females (14.7 X BW) + 496 1.6-2.4
RestingResting EnergyEnergy ExpenditureExpenditure CalculationsCalculations andand ActivityActivity FactorsFactors
BW = Body Weight in Kg World Health Organization, 2010
Performance Performance MeasurementMeasurementTime to Exhaustion
◦ Treadmill run to exhaustion @70% VO²max◦ Time to Exhaustion : The point when the subject can no longer
maintain exercise intensity For 15 seconds
◦ Reliability “Finding that there was no significant difference between
trials enables future researchers to utilize the Robinson protocol with confidence that the trials will consistently be the same.” (Robinson, 2001)
◦ Face Validity
(Walsh, 2010)
Performance Performance MeasurementMeasurementRate of Perceived
Exertion◦ Validated Borg RPE
Scale Criterion-Related
Validity Correlation w/ HR
Reliable (r=0.86) (Chen, 2002)
◦ An ordinal scale◦ Verbally Explained◦ The greater the exertion
felt the greater the number reported by the individual being tested
ProcedureProcedureTrial 1
◦Prior to any dietary manipulations◦Standard Warm-up◦Timed run to Exhaustion ◦Evaluation of RPE every 3 minutes
ProcedureProcedureDiets Begin
◦High Fat Diet for 7 days◦Carbohydrate Loading for 3 days
following the High Fat Diet Trial Two
◦Day 11◦Performed the same way as trial 1
Statistical AnalysisStatistical AnalysisTwo way ANOVA with Repeated Measures
◦ Independent Variable: Gender (Male and Female)
◦ Dependant Variable Time to Exhaustion (Pre and Post)
Two way ANOVA with Repeated Measures◦ Independent Variable: Gender (Male and
Female)◦ Dependant Variable
RPE (Pre and Post)
α < .05
ReferencesReferences Baechle, T.R., and R.W. Earle, eds. (2008). Essentials of Strength
Training and Conditioning, 3rd ed. Champaign, IL: Human Kinetics.
Lambert, E.V., Goedecke, J.H., Zyl, C.V., Murphy, K., Hawley, J.A., Dennis, S.C., & Noakes, T.D.(2001). High fat diet versus habitual diet prior to carbohydrate loading: Effects on exercise metabolism and cycling performance. International Journal of Sport Nutrition and Exercise Metabolism,11(2), 209-225.
Venables, M.C., Achten, J., &Jeukendrup, A.E. (2005). Determinants of fat oxidation during exercise in healthy men and women: A cross-sectional study. J.Appl Physiol, 98(1), 160-167.
Havemann, L., West, S.J., Goedecke, J.H., Macdonald, I.A., St. Clair Gibson, A., Noakes, T.D. & Lambert, E.V. (2006). Fat Adaptation followed by carbohydrate loading compromises high-intensity sprint performance. J Appl Physiol, 10,0 194-202. doi:10.1152/japplphysiol.00813.2006
Sherman, M.W., & Leenders (1995). Fat loading: The next magic bullet?. International Journal of Sport Nutrition, 5(S1-S12)
Walsh, A.L., Gonzalez, A.M., Ratamess, N.A., Kang, J., & Hoffman, J.R. (2010). Improved time to exhaustion following ingestion of energy drink Amino Impact. Journal of the International Society of Sport Nutrition. 7(14), 1-6.
ReferencesReferences Tarnopolsky, L.J., Tarnopolsky, S.A., & MacDougall, J.D. (1990).
Gender differences in substrate for endurance exercise. J. Appl. Physiol, 68: 302-308
Sedlock, D.A. (2008). The latest approach on carbohydrate loading: A practical approach. Current Sports Medicine Reports, 7 (4), 209-213.
Burke, L.M., Angus, D.J., Cox, R.C., Cummings, N.K., Febbraio, M.A., Gawthorn, K.,Hawley, J.A., Minehan, M., Martin, D.T., & Hargreaves, M. (2000). Effect of fat adaptation and carbohydrate restoration on metabolism and performance during prolonged cycling. J Appl Physiol, 89(6), 2413-2421.
Tarnopolosky, M.A., Zawada, C., Richmond, L.B., Carter, S., Shearer, J., Graham, T., & Philips, S.M. (2001). Gender differences in carbohydrate loading are related to energy intake. J. Appl Physiol, 91(1), 225-230.
Conlee, R.K., Hammer, R.L., Winder, W.W., Bracken, M.L., Nelson, A.G., & Barnett, D.W. (1990). Glycogen relpletion and exercise endurance in rats adapted to a high fat diet. Metabolism, 39 (3), 289-294.
Lambert, E.V., Speechly, D.P., Dennis, S.C., Noakes, T.D. (1994). Enhanced endurance in trained cyclists during moderate intensity exercise following 2 weeks adaptation to high fat diet. Eur J Appl Physiol, 69, 287-293.
ReferencesReferences Weltman, A., Snead, D., Stein, P., Seip, R., Schurrer,
R., Rutt, R., & Weltman, J. (2007). Reliability and validity of a continuous incremental treadmill protocol for the determination of lactate threshold, fixed blood lactate concentrations, and VO2 max. Int J Sports Med, 11 (1), 26-32.
Chen, M.J., Fan, X., Moe, S.T. (2002). Criterion-related validity of the Borg ratings of percieved exertion scale in healthy individuals: A meta-analysis. Journal of Sports Sciences, 11 (1), 873-899.
Billat, V., Renoux, J. C., Pinoteau, J., & Petit, B. (1994). Reproducibility of running time to exhaustion at VO2 max in subelite runners. Medicine and Science in Sports and Exercise, 26 (2), 254.
ReferencesReferences A. S. Jackson, M. L. Pollock, J. E. Graves and M. T.
Mahar (1988). Reliability and validity of BIA in determining body composition. J Appl Physiol .64: 529-534
Robinson, E.M., Graham, L.B., Headley, S.A. (2001). The Reliability of a run to exhaustion. Journal of Exercise Physiology.
Bruce, R. A., F. Kusomi, and D. Hosmer. Maximal oxygen uptake and nomographic assessment of functional aerobic impairment
in cardiovascular disease. Am. Heart J. 85: 546–562, 1973.