Influence of Increased Duration or Intensity on Training Load as evaluated by EPOC and TRIMPS Heikki Rusko Department of Biology of Physical Activity, University of Jyväskylä, and KIHU - Research Institute for Olympic Sports Jyväskylä, FINLAND
Training Effect - Training Effect - Disturbance of Homeostasis Disturbance of Homeostasis VO 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 years and thereafter only small changes occur. Why? Because disturbance of homeostasis induced by training is necessary to obtain training effect for both athletes and beginners Do we know when our homeostasis is disturbed and is longer duration at lower intensity better than shorter duration at higher intensity?
How to measure Disturbance of How to measure Disturbance of Homeostasis - Training Load? Homeostasis - Training Load? Heart rate: time at diff. intensities, not enough? Blood lactate: invasive, time consuming, momentary? Stress hormones: invasive, expensive, time consuming, requires laboratory analysis? RPE: feelings of fatigue, need for recovery TRIMP: Training Impulse (Bannister 1991): Time x relative intensity x multiplying factor (blood lactate vs. relative exercise intensity) Accumulates also during low intensity recovery exercise Not totally physiological index
EPOC: Excess Postexercise Oxygen Consumption E.g. Brooks & Fahey, EXERCISE PHYSIOLOGY, John Wiley & Sons Inc 1984: ”In reality, the cause of Excessive Postexercise Oxygen Consumption (EPOC) is the general disturbance to homeostasis brought on by exercise” ”EPOC integrates the effects of increase in body temperature, changes in stress hormone and metabolite levels, changes in intracellular ion concentrations, etc… after exercise” EPOC could be a physiological measure for disturbance of homeostasis, exercise induced fatigue accumulation and recovery time needed after exercise
Purpose Purpose To evaluate the effect of increased duration or intensity of exercise on training load as evaluated by EPOC meas , EPOC pred and TRIMP To evaluate the differences between EPOC meas , EPOC pred and TRIMP
Methods Methods Subjects Three treadmill running exercises 8 males (3% slope) Age 28 4 years (mean SD) Normal: CV21/68% Weight 81 15 kg 21 min at 9,3 km/h, 68% vVO 2max Height 180 4 cm Increased Intensity: BMI 25 4 (%Fat 17 5) CV21/79% VO 2max 52 8 ml/kg min -1 21 min at 10,8 km/h, 79% 13,6 2,1 km/h vVO 2max vVO 2max 10,8 2,2 km/h vRCT Increased Duration: 8,1 1,5 km/h vLT CV40/68% (3% slope) 40 min at 9,3 km/h, 68% vVO 2max Measurements: VO 2 (Sensor Medics), RR-Intervals (Polar RR- recorder), blood lactate concentration (EBIO 6666), RPE
EPOC meas and TRIMP TRIMP EPOC meas and 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 Athletic Performance. In: MacDougall, J.D., Wenger, H.A. & Green, H.J. (Eds.) Physiological Testing of High- Performance Athlete 2 nd ed. Human Kinetics, Champaign, Illinois.
pred EPOC pred EPOC EPOC pred : EPOC t = EPOC t-1 + f(EPOC t , %HR t , Δt) Neural Network computational model based on the relations between EPOC vs. intensity of exercise as the %VO 2max (%HR max ), duration of exercise and On-Off information Saalasti S. 2003: Neural networks for heart rate time series analysis. Ph.D. Dissertation. Department of Mathematical Information Technology, University of Jyväskylä, Finland Rusko, H.K., Pulkkinen, A., Saalasti, S., Hynynen, E., & Kettunen, J. Pre-prediction of EPOC: A tool for monitoring fatigue accumulation during exercise? Medicine and Science in Sports and Exercise, 35: S183, 2003.
Description of exercises Description of exercises VO 2 as 50 CV21/68% expected: VO 2 (ml/kg/min) 40 CV21/79% higher with CV40/68% 30 increased Max 20 RCT intensity LT 10 0 0 5 10 15 20 25 30 35 40 45 50 55 Time (min) 200 Heart rate as 180 CV21/68% Heart Rate (bpm) expected: 160 CV21/79% 140 continued to CV40/68% Max 120 increase with RCT 100 increased LT 80 duration 60 0 5 10 15 20 25 30 35 40 45 50 55 Time (min)
12 10 Blood lactate Blood lactate (mM) CV21/68% as expected: 8 CV21/79% higher with 6 CV40/68% increased Max 4 RCT intensity 2 LT 0 0 10 20 30 40 50 60 70 Time (min) 10 9 8 RPE CV21/68% 7 CV21/79% 6 as expected: CV40/68% RPE 5 Max continued to 4 RCT 3 increase with 2 LT increased 1 0 duration 0 10 20 30 40 50 60 70 Time (min) Which one induced a greater disturbance of homeostasis?
Accumulation of TRIMP and EPOC pred Accumulation of TRIMP and EPOC pred 120 TRIMP 100 greater change TRIMP (arb. units) 80 with increased CV21/68% 60 CV21/79% duration CV40/68% 40 20 0 0 10 20 30 40 50 Time (min) EPOC 250 pred greater change 200 EPOCpred (ml/kg) with increased 150 CV21/68% CV21/79% duration 100 CV40/68% And decreased 50 during recovery 0 0 10 20 30 40 50 60 Time (min)
Comparison of exercises Comparison of exercises Intensity 9,0 190 p<0.01 p<0.01 p<0.01 8,0 185 induced a 7,0 180 Heart Rate (bpm) RPE / bLa (mM) greater 6,0 175 5,0 change: RPE, 170 4,0 bLa, peakHR, 165 3,0 2,0 160 EPOC meas 1,0 155 0,0 150 RPE bLa HR Duration CV21/68% CV21/79% CV40/68% 180 induced a p<0.01 160 p<0.01 greater 140 CV21/68% CV21/79% CV40/68% change: 120 EPOC pred , 100 p<0.01 80 TRIMP 60 40 20 0 EPOCmeasured EPOCpred TRIMP
and pred High Correlation between EPOC pred and High Correlation between EPOC TRIMP TRIMP 350 300 R 2 = 0,75 250 EPOCpred (ml/kg) 200 150 100 50 0 0 20 40 60 80 100 120 140 TRIMP (arb. units)
Why difference between EPOC meas vs. EPOC pred and TRIMP? LT RCT CV21/69% CV21/78% CV40/69% 100 90 80 70 % 60 50 40 30 %vVO2max % HRR EPOC 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 Conclusions Increase in training intensity from 68% to 79% vVO 2max for 21 min exercise induced a greater disturbance of homeostasis (increase in training load) than increase in training duration from 21 to 40 min at 68%vVO 2max based on Heart rate Blood lactate RPE Measured EPOC TRIMP and EPOC pred were more sensitive to increase in training duration than intensity at the present training intensities
Conclusions Conclusions TRIMP and EPOC pred integrated similarly the intensity and duration of exercise EPOC pred and TRIMP depend very much on the % HR and %HRR level which may differ between subjects having different training background Calculation of EPOC pred and TRIMP should take into account the differences in individual ”threshold” –values EPOC pred can give dynamic information on the accumulation of training load and allows calculation of time needed for recovery (decrease of EPOC pred to resting level)
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