The comparison EPOC duration and magnitude between different exercise intensities PDF

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Excess post exercise oxygen consumption: a comparison between exercise intensities Introduction Whilst recovering from exercise there is an increase in oxygen uptake, this is called excess post exercise oxygen consumption (EPOC). The raise of oxygen consumption results in an increase of energy expenditure, which contributes towards the overall metabolic cost of exercise (Townsend et al. 2013). EPOC is the total oxygen consumed in recovery minus the total theoretical oxygen consumed at rest (McArdle, Katch and Katch, 2010). EPOC duration is how long after exercising your volume of oxygen uptake (V O2) takes to return to baseline levels. EPOC magnitude is dependent on duration and intensity of the exercise (Børsheim & Bahr, 2003). EPOC is suggested to be an exercise-induced disturbance in homeostasis, increasing the tissue temperature and changes in electrolyte, metabolite and hormone levels (Brooks & Fahey, 1985), previously known as oxygen debt. Oxygen (O2) debt can be defined as the total amount of O2 that is needed to recover from exercise (Scarabello, Heigenhauser & Wood, 1991). EPOC is the numerical value for O2 consumption, whereas O2 debt is the amount of O2 needed to remove lactate from the system (McArdle et al. 2010). Research by Fletcher and Hopkins (1907) observed oxygen debt when experimenting with working muscles in frogs’ legs. Finding, when a frog legs muscle had been contracting lactic acid was produced although adding O2 meant it disappeared. It was later found that the decline in lactic acid in the blood did not decrease until the recovery period had started (Margaria, Edwards & Dill, 1933). Exercise intensity has been found to effect EPOC magnitude the first 2 hours of exercise and 5 hours after recovery (Bahr & Sejersted, 1991). With low intensity exercise, no EPOC effects were found after 20 minutes (Børsheim et al. 2003). A curvilinear relationship was found between EPOC magnitude and intensity and duration of the exercise (Børsheim et al. 2003). O2 deficit is the area between the curve of actual V O2 and required V O2 (Gore & Withers, 1990). Representing the depletion of phosphagens in the working muscles the O2 deficit changes the body O2 stores and the Adenosine triphosphate (ATP) generation (Gore et al. 1990). The greater the O2 deficit, the larger the O2 debt. Knowing this, the aims and hypothesis were set. The aim of this experiment was to compare EPOC duration and EPOC magnitude between different exercise intensities. Following research, the directional hypothesis was predicted the greater the exercise intensity of exercise, the greater the EPOC duration and EPOC magnitude, during cycle ergometry.

Methods Sample 16 participants (2 female and 14 male) signed consent to participate in the experiment (mean ± SD age 20 years ± 0.73 years, height 1.77 metres ± 0.07 metres and mass 74.65 kg± 10.08 kg). They were all healthy enough to participate (found by using self-reported health). The experiment provided a favourable ethical opinion. Instrumentation & Procedures Conditions of the lab were collected using the Barometer (Fortin Barometer, Russel Scientific, UK) (mean ± SD Barometric Pressure 763.69 mmHg ± 3.84 mmHg, Temperature 21.9 ˚c ± 0.71 ˚C and humidity 55.13% ± 9.49%). Participants were then told if they would be participating in low intensity or moderate intensity exercise. Mass of the participants was collect using digital weighing scales (Seca 770, Seca, UK) and height collected using Stadiometer (Seca 213, Seca, UK) (mean ± SD Mass 74.65 kg ± 10.08 kg, Height 1.77 m ± 0.07m). The participants then sat on the Cycle Ergometer (Peak Bike 894E, Monark, Sweden) with the mouth piece connected to the Douglas Bag Gas collection system (Cranlea, UK) with a T-shaped Non Rebreathing Value (2700 series, Hans Rudolph, USA). Participants rested for 5 minutes (timed using Stop watches, Fastime 21, Fastime, Uk) in a relaxed condition with the mouth piece breathing, with the nose clip, into the Douglas bags. Resting data was collected for the final minute of the rest. Depending on participant sex, the wattage varied (see table 1). The participant then undertook 10 minutes of constant intensity exercise, corresponding to the wattage showed in table 1. For the last minute of exercise (minute 9), they placed the mouth piece into the mouth alongside placing the nose clip on their nose. The post exercise measurement was taken for 60 seconds continuously until 20 minutes have passed or until they reach their baseline levels of pre-exercise, whichever occurred first. Each Douglas bag holder contained four Douglas bags meaning the bags were continuously swapped over and analysed (Bahr et al. 1991). Using the Gas Analyser (Rapidox 3100, Cambridge Sensotec, UK) the fraction of expired oxygen and carbon dioxide, per Douglas Bag, were calculated. These were given in the form of percentages, so by dividing by 100, it was converted to decimals. After, using the Dry Gas Meter (Harvard Apparatus, USA) volume and temperate of the gas in the Douglas bags were recorded (Bahr et al. 1991).

Table 1: shows the wattage depending on sex and intensity of exercise.

Low Intensity

Moderate Intensity

Male

75 W

150 W

Females

50 W

100 W

Data Analysis Standardised equations were used to calculate V E, VO2, V CO2 and RER (see appendix 7). EPOC duration and EPOC magnitude were also calculated (see appendix 6). Effect size were also calculated using standardised equations (see appendix 5). The r equation was used. With the group sizes r-1 = small effect; .3 = medium effect; .5 = large effect. Using IBM SPSS Statistics 25 (USA, Chicago), a ran a test of normality (Shapiro-Wilk), one of the data was normally distributed and one was not so its assumed that the data was not normally distributed (p=0.017, p=0.165, p=0.015, p=0.488), so a non-parametric test was ran (Mann-Whitney U) on EPOC magnitude and Duration. The p value used was p ≥ 0.05. Results The mean EPOC duration was 10.5 minutes ± 6.01 minutes and the mean EPOC magnitude was 2.19 litres (l) ± 1.87 l. There was a statistical significance found with EPOC duration (p=0.022) and EPOC magnitude (p=0.002). when statistically analysed with Man Whitney U as both values were less than the P value 0.05. Table 2: shows the mean ± SD EPOC magnitude and EPOC duration for low and moderate intensity Moderate Intensity

Low Intensity

EPOC Magnitude (l)

3.4 ± 1.87

0.98 ± 0.9

EPOC Duration (minutes)

13.87 ± 5.49

7.13 ± 4.61

The effect size calculations (see appendix 5) showed that EPOC duration and magnitude had a large effect. EPOC magnitudes Z value was equal to p=-2.941 and EPOC durations Z value was p=-2.265. Showing EPOC duration and magnitude to be meaningful. Discussion

The aim of the experiment was to compare EPOC duration and EPOC magnitude between different exercise intensity and the hypothesis was predicted the greater the exercise intensity of exercise, the greater the EPOC duration and EPOC magnitude, during cycle ergometry. Finding that there was a statistical significance, effect size calculations were run. The effect size found EPOC duration and Magnitude to be meaningful. The EPOC magnitude result for moderate intensity was 3.4 l ± 1.87 l and for low intensity was 0.98 l ± 0.9 l. EPOC duration for moderate intensity was 13.87 minutes ± 5.49 minutes and for low intensity was 7.13 minutes ± 4.61 minutes. The increase in the means from moderate intensity to low intensity shows a positive correlation between both EPOC magnitude and EPOC duration with exercise intensity. As the exercise intensity increases, so do both components of EPOC. Intensity has an impact on EPOC duration and magnitude. It was found that the exercise intensity affected EPOC duration and EPOC magnitude (Larsen, Welde, Martins & Tjønna, 2014), whereas exercise duration affects EPOC duration (Sedlock, Fissinger & Melby, 1989). EPOC following high intensity exercises has these effects on the body; resynthesising of ATP and PCr (Tomlin & Wenger, 2011), resynthesize lactate to glycogen (Cori Cycle) (Wood, 1991), oxidise lactate in energy metabolism (Bangsbo, Graham, Johansen & Saltin, 1994), restore O2 to myoglobin and blood (Tomlin et al. 2011), restore thermogenic effects of elevated core temperature (McArdle et al. 2010), thermogenic effects of hormones and restoration of elevated heart rate and ventilation (McArdle et al. 2010). Maehlum, Grandmontagne, Newsholme & Sejersted (1986) used cycling for 80 minutes (10-30 minute intervals with 5 minute breaks) at 70 % of V O2max, finding the mean EPOC magnitude of 26 l. They found that EPOC can have this effect for up to 24 hours. A curvilineal relationship is found between EPOC magnitude and duration with exercise intensity (Børsheim et al. 2003). EPOC has a large anaerobic component and lactate accumulation, meaning that EPOC has the capability to resynthesise lactate to glycogen. Whilst exercising the body temperature increases to about 3 oC, meaning the elevated temperature stimulates metabolism to increase recovery O2 consumption (McArdle et al. 2010). Furthermore, up to 10% of the recovery O2 consumption reloads the blood returning to the lungs from the active muscles. The ventilation volumes are also 8 to 10 times more than the resting requirements (McArdle et al. 2010). EPOC can be affected by different types of exercise, this is because of the variety of slow twitch fibre amounts can vary upon area of the body. There would also be a different response dependant on the size of muscle. Implying that EPOC would be larger on lower

body work (Vianna, Werneck, Coelho, Damasceno & Reis, 2014). Vianna et al. (2014) compared a bench press with a half squat, finding that EPOC was higher within the half squat, providing evidence to what was previously stated. Measuring training status with EPOC magnitude and duration is incredibly difficult as there is not a study design that would work. This is difficult because you cannot expect an untrained individual to work for the same duration or intensity as a trained athlete (Børsheim & Bahr, 2003). Sedlock (1994) tried to compare fit with unfit males, getting them to cycle at 50% of their V O2 peak until 300 kcals were used. There was no difference found between the two groups on EPOC magnitude and duration. Contrasting this, Chad and Quigley (1991) found that well trained women had a higher V O2 than the untrained group. Chad et al. (1991) suggested that the difference in trained and untrained participants may be because of the higher rate of post exercise fat utilisation. Few studies have been done to assess EPOC duration and magnitude with females. Sedlock (1991) assessed females exercising at either 40% or 60% of their V O2max for a duration to that burned 200 kcals. There was no difference found between the two intensities on EPOC duration or magnitude. However, another study found that females undergoing cycling exercise at 50% and 75% of their V O2 max found that the higher intensity exercises resulted in a greater EPOC duration and magnitude (Phelain, Reinke, Harris & Melby, 1997). The results could differ between sexes because energy expenditure can differ throughout the stages of menstruation (Solomon, Kurzer & Calloway, 1982). The limitations of the experiment were: collection of gas, sample size and data analysis. Using Douglas bags are not as reliable as breath by breath. However, using breath by breath, some data can be lost in the process of analysing it. The changing of the Douglas bags meant that small amounts of breath was lost and not analysed. The sample size was not large, meaning the findings are harder to generalise. Trying to resolve this, effect size calculations were done to ensure if any of the data is meaningful. Finally, we used a non-parametric test as only of the results were normally distributed, assuming the data was not normally distributed. This is a limitation because a non-parametric test is not as thorough as a parametric test as the difference could be from normal distribution. Conclusion It was found that there was an increase in EPOC duration and EPOC magnitude, with an increased exercise intensity. However, no statistical difference was found. Meaning we must

reject the null hypothesis. Effect size for EPOC duration and magnitude gave meaningful values. For further research, it would be suggested larger samples are used as most studies have relatively small samples. With more focus into the different effects on EPOC as the literature tends to be contradicting. Finally, separating the genders to further the look into gender difference from EPOC. References: Bahr, R. O. A. L. D., & Sejersted, O. M. (1991). Effect of feeding and fasting on excess postexercise oxygen consumption. Journal of Applied Physiology, 71(6), 2088-2093. Bahr, R., & Sejersted, O. M. (1991). Effect of intensity of exercise on excess postexercise O2 consumption. Metabolism-Clinical and Experimental, 40(8), 836-841. Bangsbo, J., Graham, T., Johansen, L., & Saltin, B. (1994). Muscle lactate metabolism in recovery from intense exhaustive exercise: impact of light exercise. Journal of Applied Physiology, 77(4), 1890-1895. Børsheim, E., & Bahr, R. (2003). Effect of exercise intensity, duration and mode on postexercise oxygen consumption. Sports medicine, 33(14), 1037-1060. Brooks, G.A., & Fahey, T.D. (1985). Human Bioenergetics and its applications. Exercise Physiology, 189-215. Chad, K. E., & Quigley, B. M. (1991). Exercise intensity: effect on postexercise O2 uptake in trained and untrained women. Journal of Applied Physiology, 70(4), 1713-1719. Fletcher, W. M., & Hopkins, F. G. (1907). Lactic acid in amphibian muscle 1. The Journal of physiology, 35(4), 247-309. Gore, C. J., & Withers, R. T. (1990). The effect of exercise intensity and duration on the oxygen deficit and excess post-exercise oxygen consumption. European journal of applied physiology and occupational physiology, 60(3), 169-174. Larsen, I., Welde, B., Martins, C., & Tjønna, A. E. (2014). High‐and moderate‐intensity aerobic exercise and excess post‐exercise oxygen consumption in men with metabolic syndrome. Scandinavian journal of medicine & science in sports, 24(3), e174-e179.

Maehlum, S., Grandmontagne, M., Newsholme, E. A., & Sejersted, O. M. (1986). Magnitude and duration of excess postexercise oxygen consumption in healthy young subjects. Metabolism-Clinical and Experimental, 35(5), 425-429. Margaria, R. O. D. O. L. F. O., Edwards, H. T., & Dill, D. B. (1933). The possible mechanisms of contracting and paying the oxygen debt and the role of lactic acid in muscular contraction. American Journal of Physiology-Legacy Content, 106(3), 689-715. McArdle, W. D., Katch, F. I., & Katch, V. L. (2010). Exercise physiology: nutrition, energy, and human performance. Lippincott Williams & Wilkins. Phelain, J. F., Reinke, E., Harris, M. A., & Melby, C. L. (1997). Postexercise energy expenditure and substrate oxidation in young women resulting from exercise bouts of different intensity. Journal of the American College of Nutrition, 16(2), 140-146. Scarabello, M., Heigenhauser, G. J. F., & Wood, C. M. (1991). The oxygen debt hypothesis in juvenile rainbow trout after exhaustive exercise. Respiration physiology, 84(2), 245-259. Sedlock, D. A. (1991). Effect of exercise intensity on postexercise energy expenditure in women. British journal of sports medicine, 25(1), 38-40. Sedlock, D. A. (1994). Fitness level and postexercise energy expenditure. The Journal of sports medicine and physical fitness, 34(4), 336-342. Sedlock, D. A., Fissinger, J. A., & Melby, C. L. (1989). Effect of exercise intensity and duration on postexercise energy expenditure. Medicine and Science in Sports and Exercise, 21(6), 662-666. Solomon, S. J., Kurzer, M. S., & Calloway, D. H. (1982). Menstrual cycle and basal metabolic rate in women. The American journal of clinical nutrition, 36(4), 611-616. Tomlin, D. L., & Wenger, H. A. (2001). The relationship between aerobic fitness and recovery from high intensity intermittent exercise. Sports Medicine, 31(1), 1-11. Townsend, J. R., Stout, J. R., Morton, A. B., Jajtner, A. R., Gonzalez, A. M., Wells, A. J., ... & Edward, H. (2013). Excess Post-Exercise Oxygen Consumption (EPOC) following multiple effort sprint and moderate aerobic exercise. Kinesiology, 45(1).

Vianna, J. M., Werneck, F. Z., Coelho, E. F., Damasceno, V. O., & Reis, V. M. (2014). Oxygen uptake and heart rate kinetics after different types of resistance exercise. Journal of human kinetics, 42(1), 235-244. WOOD, C. M. (1991). Acid-base and ion balance, metabolism, and their interactions, after exhaustive exercise in fish. Journal of Experimental Biology, 160(1), 285-308. Appendix: EPOC Duration: Appendix 1- Test of normality for EPOC Duration Tests of Normality Kolmogorov-Smirnova Intensity

Statisti

Shapiro-Wilk Statisti

df

Sig.

c

df

Sig.

Duration (W)

c

EPOC duration

moderate

.276

8

.074

.779

8

.017

(minutes)

low

.261

8

.116

.874

8

.165

a. Lilliefors Significance Correction

Appendix 2- test of difference (Mann-Whitney U) for EPOC Duration Test Statisticsa EPOC duration (minutes) Mann-Whitney U

10.500

Wilcoxon W

46.500

Z

-2.265

Asymp. Sig. (2-tailed)

.024

Exact Sig. [2*(1-tailed

.021b

Sig.)] Exact Sig. (2-tailed)

.022

Exact Sig. (1-tailed)

.011

Point Probability

.001

a. Grouping Variable: Intensity Duration (W) b. Not corrected for ties. EPOC Magnitude: Appendix 3- Test of normality for EPOC Magnitude

Tests of Normality Kolmogorov-Smirnova Intensity

Statisti

Duration

c

EPOC

moderate

.189

magnitude

low

.381

Shapiro-Wilk Statisti

df

Sig.

c

df

8

.200*

.927

8

.488

8

.001

.774

8

.015

*. This is a lower bound of the true significance. a. Lilliefors Significance Correction Appendix 4- Test of difference (Mann-Whitney U) for EPOC Magnitude Test Statisticsa EPOC magnitude Mann-Whitney U

4.000

Wilcoxon W

40.000

Z

-2.941

Asymp. Sig. (2-tailed)

.003

Exact Sig. [2*(1-tailed

.002b

Sig.)] Exact Sig. (2-tailed)

.002

Exact Sig. (1-tailed)

.001

Point Probability

.000

a. Grouping Variable: Intensity Duration b. Not corrected for ties.

Sig.

Appendix 5- Effect size calculations for EPOC magnitude and EPOC duration

Appendix 6- Calculations for EPOC duration and Magnitude

Appendix 7- Calculations for V E, VO2, V CO2 and RER...