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Training Effect -Disturbance of HomeostasisVO 2max of beginner exercisers increases 10-20%during the first 10-20 weeks and thereafter levels off.VO 2max of endurance athletes increases for ~1-3 yearsand thereafter only small changes occur.Why? Because disturbance of homeostasis inducedby training is necessary to obtain training effect forboth athletes and beginnersDo we know when our homeostasis is disturbed andis longer duration at lower intensity better thanshorter duration at higher intensity?

EPOC:Excess Postexercise Oxygen ConsumptionE.g. Brooks & Fahey, EXERCISE PHYSIOLOGY, JohnWiley & Sons Inc 1984: ”In reality, the cause of Excessive PostexerciseOxygen Consumption (EPOC) is the generaldisturbance to homeostasis brought on byexercise” ”EPOC integrates the effects of increase in bodytemperature, changes in stress hormone andmetabolite levels, changes in intracellular ionconcentrations, etc… after exercise” EPOC could be a physiological measure for disturbance of homeostasis, exercise induced fatigue accumulation and recovery time needed after exercise

PurposeTo evaluate the effect of increased duration orintensity of exercise on training load as evaluatedby EPOC meas , EPOC pred and TRIMPTo evaluate the differences between EPOC meas ,EPOC pred and TRIMP

Subjects 8 males Age 28 4 years(mean SD) Weight 81 15 kg Height 180 4 cm BMI 25 4 (%Fat 17 5) VO 2max 52 8 ml/kgmin -1 vVO 2max 13,6 2,1 km/h vRCT 10,8 2,2 km/h vLT 8,1 1,5 km/h (3% slope)MethodsThree treadmillrunning exercises(3% slope) Normal: CV21/68% 21 min at 9,3 km/h, 68%vVO 2max Increased Intensity:CV21/79% 21 min at 10,8 km/h, 79%vVO 2max Increased Duration:CV40/68% 40 min at 9,3 km/h, 68%vVO 2maxMeasurements: VO 2 (Sensor Medics), RR-Intervals (Polar RRrecorder),blood lactate concentration (EBIO 6666), RPE

EPOC meas and TRIMP EPOC meas : 15-min recovery VO 2 – resting VO 2(sitting) TRIMP: = t x %HRR x 0.64e 1,92(%HRR) = duration x relative intensity x multiplying factor Bannister E.W. 1991: Modelling Elite AthleticPerformance. In: MacDougall, J.D., Wenger, H.A. &Green, H.J. (Eds.) Physiological Testing of High-Performance Athlete 2 nd ed. Human Kinetics,Champaign, Illinois.

EPOC pred EPOC pred : EPOC t = EPOC t-1 + f(EPOC t, %HR t, Δt) Neural Network computational model based on therelations between EPOC vs. intensity of exercise as the%VO 2max (%HR max ), duration of exercise and On-Offinformation Saalasti S. 2003: Neural networks for heart rate timeseries analysis. Ph.D. Dissertation. Department ofMathematical Information Technology, University ofJyväskylä, FinlandRusko, H.K., Pulkkinen, A., Saalasti, S., Hynynen, E., & Kettunen, J. Pre-prediction of EPOC: A tool for monitoringfatigue accumulation during exercise? Medicine and Science in Sports and Exercise, 35: S183, 2003.

Description of exercisesVO2 (ml/kg/min)5040302010CV21/68%CV21/79%CV40/68%MaxRCTLTVO 2 asexpected:higher withincreasedintensity00 5 10 15 20 25 30 35 40 45 50 55Time (min)Heart Rate (bpm)20018016014012010080600 5 10 15 20 25 30 35 40 45 50 55CV21/68%CV21/79%CV40/68%MaxRCTLTHeart rate asexpected:continued toincrease withincreaseddurationTime (min)

12Blood lactate (mM)108642CV21/68%CV21/79%CV40/68%MaxRCTLTBlood lactateas expected:higher withincreasedintensityRPE01098765432100 10 20 30 40 50 60 70Time (min)0 10 20 30 40 50 60 70Time (min)CV21/68%CV21/79%CV40/68%MaxRCTLTRPEas expected:continued toincrease withincreaseddurationWhich one induced a greater disturbance of homeostasis?

Accumulation of TRIMP and EPOC predTRIMP (arb. units)12010080604020CV21/68%CV21/79%CV40/68%TRIMPgreater changewith increasedduration00 10 20 30 40 50Time (min)250EPOC predEPOCpred (ml/kg)200150100500CV21/68%CV21/79%CV40/68%greater changewith increaseddurationAnd decreasedduring recovery0 10 20 30 40 50 60Time (min)

RPE / bLa (mM)1801601401201008060402009,08,07,06,05,04,03,02,01,00,0Comparison of exercisesp

High Correlation between EPOC predTRIMPandpred and350EPOCpred (ml/kg)300250200150100500R 2 = 0,750 20 40 60 80 100 120 140TRIMP (arb. units)

Why difference between EPOC meas vs.EPOC pred and TRIMP?LT RCT CV21/69% CV21/78% CV40/69%1009080%7060504030%vVO2max%HRREPOC pred and TRIMP start to accumulate with time at ~50-60%HRR (over LT)Present subjects had higher VO 2max , LT and RCT than”average persons”: e.g. LT 63%HRR (78%HRmax)

Conclusions Increase in training intensity from 68% to 79%vVO 2max for 21 min exercise induced a greaterdisturbance of homeostasis (increase in trainingload) than increase in training duration from 21to 40 min at 68%vVO 2max based on Heart rate Blood lactate RPE Measured EPOC TRIMP and EPOC pred were more sensitive toincrease in training duration than intensity at thepresent training intensities

Conclusions TRIMP and EPOC pred integrated similarly theintensity and duration of exercise EPOC pred and TRIMP depend very much on the %HR and %HRR level which may differ betweensubjects having different training background Calculation of EPOC pred and TRIMP should takeinto account the differences in individual”threshold” –values EPOC pred can give dynamic information on theaccumulation of training load and allowscalculation of time needed for recovery(decrease of EPOC pred to resting level)

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