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Research Quarterly for Exercise and Sport Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/urqe20
Postexercise Energy Expenditure following Upper Body Exercise Darlene A. Sedlock
a
a
Affiliated with Purdue University , USA Published online: 26 Feb 2013.
To cite this article: Darlene A. Sedlock (1991) Postexercise Energy Expenditure following Upper Body Exercise, Research Quarterly for Exercise and Sport, 62:2, 213-216, DOI: 10.1080/02701367.1991.10608712 To link to this article: http://dx.doi.org/10.1080/02701367.1991.10608712
PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http:// www.tandfonline.com/page/terms-and-conditions
Research Quarterly for Exercise and Sport © 1991 bythe American Alliance for Health,
Physical Education, Recreation and Dance Vol. 62,No.2, pp. 213·216
Postexercise Energy Expenditure Following Upper Body Exercise
Downloaded by [New York University] at 05:50 26 May 2015
Darlene A. Sedlock This study was designed to examine the magnitude and duration ofexcess postexercise oxygen consumption (EPOC) following upper body exercise, using lower body exercise for comparison. On separate days and in a counterbalanced order, eight subjects (jour male and four female) performed a 20-min exercise at 60% of mode-specific peak oxygen uptake (YO) using an arm crank and cycle ergometer. Priorto each exercise, baseline V0 2 and heartrate (HR) were measured during thefinal 15 min of a 45-min seated rest. V02 and HR were measured continuously during thepostexercise period until baseline V02 was reestablished. No significant difference between the two experimental conditions wasfound for magnitude ofEPOC (t [7J = 0.69, P > .05). Mean (± SD) values were 9.2 ± 3.3 and 10.4 ± 5.8 kcalfor the arm crank and cycle ergometer exercises, respectively. Duration of EPOC was relatively shortand not significantly different (t [7J = 0.24, p > .05) between the upper body (22.9± 13.7 min) and lower body (24.2± 19.4 min) exercises. Within theframework of the chosen exercise conditions, these results suggest EPOC may berelated primarily to the relative metabolic rate of the activemusculature, as opposed to the absolute exercise V0 2 or quantity of activemusclemass associated with these two types of exercise.
Key words: recovery, arm ergometry, cycle ergometry, caloric expenditure
R
e su l ts of studies that have examined excess postexercise oxygen consumption (EPOC) remain equivocal as to both the magnitude and duration of this phenomenon (Bahr, Ingnes, Vaage, Sejersted, & Newsholme, 1987; Brehm & Gutin, 1986; Maehlum, Grandmon tagne, Newsholme, & Sejersted, 1986; Sedlock, Fissinger, & Melby, 1989). To date, these investigations have involved lower body exercise, most often utilizing a treadmill or cycle ergometer. Notwithstanding some studies that have addressed oxygen uptake (V0 2) kinetics specifically (Cerretelli, Shindell, Pendergast, di Prampero, & Rennie, 1977; Hagberg, Hickson, Ehsani, & Holloszy, 1980), little is known about the overall EPOC response following upper body exercise. When compared to lower body exercise, several differences exist in the physiological responses to upper body exercise that warrant an investigation of EPOC following this type of activity. Some of these include differences in peak V02 (Sawka, 1986), quantity ofactive musculature (Washburn & Seals, 1984), metabolic rate during submaximal exercise at a comparable relative (to maximum) intensity or external power output (Vokac, Bell, Bautz-Holter, & Rodahl, 1975), and thermoregula-
Darlene A. Sedlock is affiliated with Purdue University. Address correspondence to the author at Exercise Physiology Laboratory, PEHRS-Lambert 10BA, Purdue University, West Lafayette, IN 47907. Submitted: April 25, 1990 Revision accepted: October 9, 1990 ROES: June 1991
tory responses (Sawka, Pimental, & Pandolf, 1984). Both metabolic rate (Knuttgen, 1970) and core temperature (Hagberg, Mullin, & Nagle, 1980) have been proposed as mechanisms that affect the EPOC response. In contrast to the differences mentioned above, some similarities in the physiological responses to upper and lower body exercise suggest the EPOC response following these two types ofactivity might be comparable. These include the ratio of cardiac output to metabolic rate (i.e., Qc:V02 = 6:1) (Reybrouck, Heigenhauser, & Faulkner, 1975), blood lactate concentrations and other acid-base parameters (Sawka, 1986), and V02 kinetics during similar relative intensity exercise (Cerretellietal., 1977). Study of the physiology of upper body exercise is important because this type of activity is employed for manyvocational, recreational, sport, health, locomotory, and clinical diagnostic/rehabilitative reasons. Given the con troversial nature ofEPOC, the numerous mechanisms purported to be involved in the EPOC response (Gaesser & Brooks, 1984), and contemporary perspectives concerning similarities and differences in the physiological responses to upper body exercise when compared to lower body exercise, the purpose of this study was to examine the duration of the EPOC response following upper body (arm crank ergometer) exercise using lower body (cycle ergometer) exercise for comparison. It was hypothesized that upper body and lower body exercise, when performed at a comparable relative metabolic intensity, would elicit similar EPOC responses. Additionally, since magnitude of EPOC is not necessarily related to the duration (Sedlock et al., 1989), a second purpose was to quantify the magnitude ofEPOC following upper body exercise.
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Method Subjects Eight untrained subjects, four male and four female, volunteered to participate in the study. Mean (±SD) age, height, and weight were 22.3 ± 1.5 years, 173.4 ± 11.7 em, and 71.2 ± 14.4 kg, respectively. The procedures used in this studywere reviewed and approved by the institutional committee for research involving human subjects. All subjects signed a statement of informed consent.
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Procedure Research design. Each subject performed two tests for peak V0 2, one using a mechanically braked cycle ergometer (Monark) and another using an arm crank ergometer (Monark Rehab Trainer). Order of testing was counterbalanced with a minimum of 3 days separating the tests. Additionally, a 20-min submaximal exercise was performed on each ergometer atan in tensity equal to 60% of the mode-specific peak V0 2 , as this was representative of exercise conditions used by many for healthrelated reasons. This exercise intensity was also chosen because results of pilot testing indicated it would have been difficult for these untrained subjects to complete the upper body exercise at a higher relative metabolic intensity. Order of administration of the submaximal tests for each subject was identical to the order used to determine peak V0 2 • A minimum of 3 days separated each of the submaximal exercise tests. Testsforpeak V02.A con tin u ous, incrementalworkload protocol was used for each ergometer. Initial power output level for the cycle was 50 W, with subsequent increases of25 W every 2 min un til termination ofthe test. Initial power output was 12.5 W on the arm crank, with a 12.5 W increase every 2 min. Criteria for termination of the test included an increase in power output with little or no increase in V0 2, heart rate (HR) at or near agepredicted maximum, inability to main tain the prescribed cranking rate of50 rpm, or volitional termination by the subject due to fatigue. Peak V0 2 was recorded as the highest V0 2 measured during each test. Submaximal exercise tests. Subjects were transported to the laboratory in the early morning after an overnight fast and having refrained from any strenuous physical activity for 24-36 hours. After applying surface electrodes to measure HR via electrocardiography, subjects were seated in a chair, where they rested quietly for 45 min. Baseline V0 2 and HR were measured during the last 15 min of this period. Exercise was then performed using the prescribed ergometer. Immediately on termination of the exercise, subjects were again seated in a chair, while V0 2 and HR were continuously monitored until baseline V0 2 was achieved. The criterion for having achieved baseline was that the V0 2 averaged over 5 consecutive min was equal to the preexercise value.
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Measurements. V0 2 was measured by open-circuit spirometry. Subjects inspired room air via a low-resistance breathing valve (Hans-Rudolph), and expired air was measured for volume and analyzed for fractional oxygen and carbon dioxide using an automated system (Quinton Q-Plex I). V0 2 was converted to kcal using the caloric equivalent of a liter of oxygen based on the nonprotein respiratory exchange ratio (RER). Duration ofEPOC following each submaximal exercise was defined as elapsed time (min) from termination of the exercise to the first minute of the 5-min average of V0 2 that was equal to the baseline value. Magnitude of EPOC was calculated as the sum of the net caloric expenditure for each minute of the EPOC period.
Statistical Analyses All data are reported as M ± SD. A t-test for related samples was used to test for differences between the responses elicited by the arm crank and cycle ergometer exercises. Statistical significance was accepted at p < .05.
Results Results from the tests for peak V0 2 indicated the arm crank peak V0 2 averaged approximately 72% ofthe value achieved during cycling. This value is consistent with the reported value of 73%, which represents the difference between upper and lower body peak V0 2 when averaged across a minimum of 18 previously reported studies (Sawka, 1986). Mean peak V0 2 was 1.94 ± 0.57 L'mirr' (27.0 ± 4.4 ml-kgl-rnin") for the arm crank and 2.68 ± 0.73 Lvmirr' (37.4 ± 5.7 ml-kgl-rnirr') for the cycle ergometer. Peak HR averaged 186.1 ± 9.7 and 188.4 ± 9.7 b-rnirr' for the upper body and lower body exercises, respectively. A description of the physiological status of the subjects during the baseline period of each experimental condition is shown in Table 1. Mean values for V02 , HR, RER, and energy expenditure indicate the subjects were in a comparable resting state for each experimental condition.
Table1. Description ofthe physiological status ofthe subjects (N= 8)during the baseline periodpreceding arm crank and cycle ergometry Variable Oxygen uptake (Lmirr') Oxygen uptake (ml.kg"min") Hear! rate [b-min"] Respiratory exchange ratio Energy expenditure [kcal-rnirr']
Arm Crank 0.26 ± 0.06 3.59 ± 0.27 67.40 ± 9.30 0.89 ± 0.03 1.28 ± 0.29
Cycle 0.24 3.41 68.40 0.91 1.24
± ± ± ±
0.05 0.23 9.70 0.03 ± 0.29
Note. Values represent M± SO.
RQES: June 1991
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Sedlock
Exercise V0 2 averaged 1.18± 0.34 L'mirr' during the arm crank exercise and 1.63 ± 0.47 Lvmin" during cycling. This represented 60.7 ± 1.19% and 60.3 ± 2.26% of the mode-specific peak V0 2, respectively. Mean HR was 136.9± lfi.Sb-rnirr' during arm cranking and 137.3±13.7 b-mirr' during cycling. RERaveraged 1.02±0.08and 1.02 ±0.04duringupperandlowerbodyexercise, respectively. Mean values for data obtained during the EPOC period are presented in Table 2. Neither the arm crank nor the cycle ergometer exercise produced a prolonged EPOC response. Additionally, there was no significant difference in the duration of EPOC between the two experimental conditions (t [7] = 0.24, p » .05). Magnitude of EPOC was small and not significantly different following the upper and lower body exercises (t [7] = 0.69, p » .05). The two experimental conditions also had no differential effect on HR or RER at the end of the EPOC period.
Discussion This study was designed to investigate the magnitude and duration of EPOC following upper body exercise, using lower body exercise for comparison. Results indicate the EPOC responses to moderate intensity arm crank and cycle ergometer exercise were not significantly different when the exercises were performed at a comparable relative metabolic intensity. Moreover, these results occurred despite a 28% lower absolute metabolic rate and exercise energy expenditure during arm crank than cycle ergometer exercise. To date, lower body exercise has been employed in the literature focused on examining the magnitude and duration of EPOC. In this regard, it has been suggested EPOC may be related to the magnitude of the disturbance to the body's resting homeostasis (Brehm & Cutin, 1986), especially since lower body exercise utilizes a large proportion of the body's skeletal muscle mass. Brehm and Cutin (1986) have proposed a model showing that recovery V0 2
Table2. Mean (±SO) values for excess postexercise oxygen consumption following arm crank and cycle ergometer exercise (N=8)
Variable
Arm Crank
Duration (min) Magnitude" (kcal) Heartrate" (b-mirr'] Respiratory exchange ratio'
22.9 9.2 78.8 0.88
± 13.7 ± 3.3 ± 12.3 ± 0.05
Cycle 24.2 10.4 76.3 0.90
± 19.4 ± 5.8 ± 10.2 ± 0.05
t*
0.24 0.69 1.03 1.21
" Sum ofthe net caloric expenditure for each minute ofthe excess postexercise oxygen consumption period. b Values measuredatthe end ofthe excess postexercise oxygen consumption period. * p » .05 for allvariables.
ROES: June 1991
increases in a curvilinear manner as a function of relative (to maximum) exercise intensity. This model is based on EPOC responses to treadmill walking and running. Results of the present study can be viewed within the context of the model proposed by Brehm and Cutin (1986). The exercise conditions of this study were not performed atseveral differentmetabolic intensities, since it was not the intent to determine the shape ofthe EPOC curve for upper body exercise as a function of relative intensity. However, since both upper body and lower body exercise were performed at the same percentage of peak V0 2 and elicited comparable EPOC responses, it could be suggested, within the context of the present research design, that EPOC may be related primarily to the relative (to maximum) perturbation to the exercising muscle mass rather than to the overall magnitude of the disturbance to the body's resting homeostasis. It could also be postulated this would occur regardless of the absolute metabolic rate, since this value was significantly different for the arm crank and cycle exercises of this study. Additionally, it might be suggested the EPOC response is independent of the quantity of muscle mass involved in upper versus lower body exercise, since this also differs for these exercise modes. Other researchers have also suggested exercise intensity is one ofthe primary factors governing the EPOC response (Knuttgen, 1970; McMiken, 1976). However, it seems this hypothesis is limited in scope since itis drawn from studies using lower body exercise exclusively. In this regard the present investigation, which employed a different quantity of muscle mass and absolute metabolic rate during exercise, adds unique support for this hypothesis. However, this is the first study to examine EPOC following upper body exercise. Therefore, much more research is needed to examine these issues. The two exercise conditions used in this study did not elicit a prolonged EPOC. These results support others who report the absence of a prolonged EPOC following moderate intensity exercise of a similar duration (Brehm & Cutin, 1986; Freedman-Akabas, Colt, Kissileff, & Pi-Sunyer, 1985; Pacy, Barton, Webster, & Carrow, 1985; Sedlock et al., 1989). An exercise intensity of 70% V0 2 max has been suggested as a threshold level necessary to produce a prolonged EPOC (Brehm, 1988). However, it seems other (as yet unidentified) factors are involved in producing a protracted EPOC. Thatis, exercise intensities of 70% V0 2 max or greater have been reported to both elicit (Bahr et al., 1987; Maehlum et aI., 1986) and fail to produce (Kaminsky, Kanter, Lesmes, & Laham-Saeger, 1987; Sedlock et aI., 1989) a lengthy EPOC period, whereas lower intensity (50% V0 2 max) longer duration exercise has been shown to result in a prolonged EPOC (Bielinski, Schutz, &Jequier, 1985). The findings ofthis study indicate the EPOCresponse following moderate intensity upper body exercise was similar to that of lower body exercise when the exercise
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was performed at equivalent relative metabolic rates. Within the limitations of the experimental design, these results suggest postexercise energy expenditure following moderate intensity exercise may be related primarily to the relative metabolic rate ofthe active musculature, as opposed to the absolute rate of exercise energy expenditure or quantity ofactive muscle mass involved in these two modes of exercise. Future work should be directed toward exploring these issues, in addition to examining the EPOC response to a variety of exercise intensity/ duration combinations.
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References Bahr, R, Ingnes, I., Vaage, 0., Sejersted, O. M., & Newsholme, E. A. (1987). Effect of duration of exercise on excess postexercise O 2 consumption. Journal ofApplied Physiology, 62, 485-490. Bielinski, R, Schutz, Y., &]equier, E. (1985). Energy metabolism during the postexercise recovery in man. American Journal ofClinical Nutrition, 42,69-82. Brehm, B. A. (1988). Elevation of metabolic rate following exercise: Implications for weight loss. SportsMedicine, 6, 72-78. Brehm, B. A., & Gutin, B. (1986). Recovery energy expenditure for steady state exercise in runners and nonexercisers. Medicine and Science in Sportsand Exercise, 18, 205-210. Cerretelli,P.,Shindell,D.,Pendergast,D.P.,diPrampero,P.E., & Rennie, D. W. (1977). Oxygen uptake transients at the onset and offset ofarm and leg work. RespirationPhysiology, 30,81-97.
Freedman-Akabas, S., Colt, E., Kissileff, H. R, & Pi-Sunyer, F. X. (1985). Lack of sustained increase in VO following exercise in fit and unfit subjects. AmericanJ~rnal ofClinical Nutrition, 41,545-549. Gaesser,G.A., & Brooks, G.A. (1984). Metabolic bases ofexcess post-exercise oxygen consumption: A review. Medicineand Science in Sportsand Exercise, 16, 29-43. Hagberg,]. M., Hickson, R C., Ehsani, A. A., & Holloszy,]. O. (1980).Fasteradjustmenttoandrecoveryfromsubmaximal
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exercise in the trained state. Journal ofApplied Physiology: Respiration, EnvironmentalandExercisePhysiology, 48, 218-224. Hagberg,]. M., Mullin,]. P., & Nagle, F.]. (1980). Effectofwork intensity and duration on recovery O 2, Journal ofApplied Physiology: Respiration, Environmental and Exercise Physiology, 48, 540-544. Kaminsky, L. A., Kanter, M. M., Lesmes, G. R, & Laham-Saeger, ]. (1987). Excess oxygen consumption following exercise ofdifferent in tensity and duration. CanadianJournalofSport Sciences, 12, 237-239. Knuttgen,H. G. (1970). Oxygen debtafter submaximal physical exercise. Journal ofApplied Physiology, 29, 651-657. Maehlum, S., Grandmontagne, M., Newsholme, E. A., & Sejersted, O. M. (1986). Magnitude and duration ofexcess postexercise oxygen consumption in healthyyoungsubjects. Metabolism, 35, 425429. McMiken, D. F. (1976). Oxygen deficit and repayment in submaximal exercise. EuropeanJournal ofAppliedPhysiology and OccupationalPhysiology, 35, 127-136. Pacy,P.]., Barton,N., Webster,]. D., &Garrow,].S. (1985). The energy cost of aerobic exercise in fed and fasted normal subjects. AmericanJournal of ClinicalNutrition, 42,764-768. Reybrouck, T., Heigenhauser, G. F., & Faulkner,]. A. (1975). Limitations to maximum oxygen uptake in arm, leg, and combined arm-leg ergometry.Journal ofAppliedPhysiology, 38,774-779. Sawka, M. N. (1986). Physiology of upper body exercise. In K. B. Pandolf (Ed.), Exercise and sport sciences reviews, vol. 14 (pp. 175-211). New York: Macmillan. Sawka,M.N.,Pimental,N.A.,&Pandolf,K.B. (1984). Thermoregulatory responses to upper body exercise. European Journal ofApplied Physiology and OccupationalPhysiology, 52, 230-234. Sedlock, D. A., Fissinger,]. A., & Melby, C. L. (1989). Effect of exercise intensity and duration on postexercise energy expenditure. Medicineand Science in Sportsand Exercise, 21, 662-666. Vokac, Z., Bell, H., Bautz-Holter, E., & Rodahl, K. (1975). Oxygen uptake/heart rate relationship in leg and arm exercise, sitting and standing. Journal ofAppliedPhysiology, 39,54-59. Washburn, R A., & Seals, D. R. (1984). Peak oxygen uptake during arm cranking for men and women.JournalofApplied Physiology, 56, 954-957.
ROES: June 1991
Research Quarterly for Exercise and Sport Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/urqe20
Postexercise Energy Expenditure following Upper Body Exercise Darlene A. Sedlock
a
a
Affiliated with Purdue University , USA Published online: 26 Feb 2013.
To cite this article: Darlene A. Sedlock (1991) Postexercise Energy Expenditure following Upper Body Exercise, Research Quarterly for Exercise and Sport, 62:2, 213-216, DOI: 10.1080/02701367.1991.10608712 To link to this article: http://dx.doi.org/10.1080/02701367.1991.10608712
PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http:// www.tandfonline.com/page/terms-and-conditions
Research Quarterly for Exercise and Sport © 1991 bythe American Alliance for Health,
Physical Education, Recreation and Dance Vol. 62,No.2, pp. 213·216
Postexercise Energy Expenditure Following Upper Body Exercise
Downloaded by [New York University] at 05:50 26 May 2015
Darlene A. Sedlock This study was designed to examine the magnitude and duration ofexcess postexercise oxygen consumption (EPOC) following upper body exercise, using lower body exercise for comparison. On separate days and in a counterbalanced order, eight subjects (jour male and four female) performed a 20-min exercise at 60% of mode-specific peak oxygen uptake (YO) using an arm crank and cycle ergometer. Priorto each exercise, baseline V0 2 and heartrate (HR) were measured during thefinal 15 min of a 45-min seated rest. V02 and HR were measured continuously during thepostexercise period until baseline V02 was reestablished. No significant difference between the two experimental conditions wasfound for magnitude ofEPOC (t [7J = 0.69, P > .05). Mean (± SD) values were 9.2 ± 3.3 and 10.4 ± 5.8 kcalfor the arm crank and cycle ergometer exercises, respectively. Duration of EPOC was relatively shortand not significantly different (t [7J = 0.24, p > .05) between the upper body (22.9± 13.7 min) and lower body (24.2± 19.4 min) exercises. Within theframework of the chosen exercise conditions, these results suggest EPOC may berelated primarily to the relative metabolic rate of the activemusculature, as opposed to the absolute exercise V0 2 or quantity of activemusclemass associated with these two types of exercise.
Key words: recovery, arm ergometry, cycle ergometry, caloric expenditure
R
e su l ts of studies that have examined excess postexercise oxygen consumption (EPOC) remain equivocal as to both the magnitude and duration of this phenomenon (Bahr, Ingnes, Vaage, Sejersted, & Newsholme, 1987; Brehm & Gutin, 1986; Maehlum, Grandmon tagne, Newsholme, & Sejersted, 1986; Sedlock, Fissinger, & Melby, 1989). To date, these investigations have involved lower body exercise, most often utilizing a treadmill or cycle ergometer. Notwithstanding some studies that have addressed oxygen uptake (V0 2) kinetics specifically (Cerretelli, Shindell, Pendergast, di Prampero, & Rennie, 1977; Hagberg, Hickson, Ehsani, & Holloszy, 1980), little is known about the overall EPOC response following upper body exercise. When compared to lower body exercise, several differences exist in the physiological responses to upper body exercise that warrant an investigation of EPOC following this type of activity. Some of these include differences in peak V02 (Sawka, 1986), quantity ofactive musculature (Washburn & Seals, 1984), metabolic rate during submaximal exercise at a comparable relative (to maximum) intensity or external power output (Vokac, Bell, Bautz-Holter, & Rodahl, 1975), and thermoregula-
Darlene A. Sedlock is affiliated with Purdue University. Address correspondence to the author at Exercise Physiology Laboratory, PEHRS-Lambert 10BA, Purdue University, West Lafayette, IN 47907. Submitted: April 25, 1990 Revision accepted: October 9, 1990 ROES: June 1991
tory responses (Sawka, Pimental, & Pandolf, 1984). Both metabolic rate (Knuttgen, 1970) and core temperature (Hagberg, Mullin, & Nagle, 1980) have been proposed as mechanisms that affect the EPOC response. In contrast to the differences mentioned above, some similarities in the physiological responses to upper and lower body exercise suggest the EPOC response following these two types ofactivity might be comparable. These include the ratio of cardiac output to metabolic rate (i.e., Qc:V02 = 6:1) (Reybrouck, Heigenhauser, & Faulkner, 1975), blood lactate concentrations and other acid-base parameters (Sawka, 1986), and V02 kinetics during similar relative intensity exercise (Cerretellietal., 1977). Study of the physiology of upper body exercise is important because this type of activity is employed for manyvocational, recreational, sport, health, locomotory, and clinical diagnostic/rehabilitative reasons. Given the con troversial nature ofEPOC, the numerous mechanisms purported to be involved in the EPOC response (Gaesser & Brooks, 1984), and contemporary perspectives concerning similarities and differences in the physiological responses to upper body exercise when compared to lower body exercise, the purpose of this study was to examine the duration of the EPOC response following upper body (arm crank ergometer) exercise using lower body (cycle ergometer) exercise for comparison. It was hypothesized that upper body and lower body exercise, when performed at a comparable relative metabolic intensity, would elicit similar EPOC responses. Additionally, since magnitude of EPOC is not necessarily related to the duration (Sedlock et al., 1989), a second purpose was to quantify the magnitude ofEPOC following upper body exercise.
213
Sedlock
Method Subjects Eight untrained subjects, four male and four female, volunteered to participate in the study. Mean (±SD) age, height, and weight were 22.3 ± 1.5 years, 173.4 ± 11.7 em, and 71.2 ± 14.4 kg, respectively. The procedures used in this studywere reviewed and approved by the institutional committee for research involving human subjects. All subjects signed a statement of informed consent.
Downloaded by [New York University] at 05:50 26 May 2015
Procedure Research design. Each subject performed two tests for peak V0 2, one using a mechanically braked cycle ergometer (Monark) and another using an arm crank ergometer (Monark Rehab Trainer). Order of testing was counterbalanced with a minimum of 3 days separating the tests. Additionally, a 20-min submaximal exercise was performed on each ergometer atan in tensity equal to 60% of the mode-specific peak V0 2 , as this was representative of exercise conditions used by many for healthrelated reasons. This exercise intensity was also chosen because results of pilot testing indicated it would have been difficult for these untrained subjects to complete the upper body exercise at a higher relative metabolic intensity. Order of administration of the submaximal tests for each subject was identical to the order used to determine peak V0 2 • A minimum of 3 days separated each of the submaximal exercise tests. Testsforpeak V02.A con tin u ous, incrementalworkload protocol was used for each ergometer. Initial power output level for the cycle was 50 W, with subsequent increases of25 W every 2 min un til termination ofthe test. Initial power output was 12.5 W on the arm crank, with a 12.5 W increase every 2 min. Criteria for termination of the test included an increase in power output with little or no increase in V0 2, heart rate (HR) at or near agepredicted maximum, inability to main tain the prescribed cranking rate of50 rpm, or volitional termination by the subject due to fatigue. Peak V0 2 was recorded as the highest V0 2 measured during each test. Submaximal exercise tests. Subjects were transported to the laboratory in the early morning after an overnight fast and having refrained from any strenuous physical activity for 24-36 hours. After applying surface electrodes to measure HR via electrocardiography, subjects were seated in a chair, where they rested quietly for 45 min. Baseline V0 2 and HR were measured during the last 15 min of this period. Exercise was then performed using the prescribed ergometer. Immediately on termination of the exercise, subjects were again seated in a chair, while V0 2 and HR were continuously monitored until baseline V0 2 was achieved. The criterion for having achieved baseline was that the V0 2 averaged over 5 consecutive min was equal to the preexercise value.
214
Measurements. V0 2 was measured by open-circuit spirometry. Subjects inspired room air via a low-resistance breathing valve (Hans-Rudolph), and expired air was measured for volume and analyzed for fractional oxygen and carbon dioxide using an automated system (Quinton Q-Plex I). V0 2 was converted to kcal using the caloric equivalent of a liter of oxygen based on the nonprotein respiratory exchange ratio (RER). Duration ofEPOC following each submaximal exercise was defined as elapsed time (min) from termination of the exercise to the first minute of the 5-min average of V0 2 that was equal to the baseline value. Magnitude of EPOC was calculated as the sum of the net caloric expenditure for each minute of the EPOC period.
Statistical Analyses All data are reported as M ± SD. A t-test for related samples was used to test for differences between the responses elicited by the arm crank and cycle ergometer exercises. Statistical significance was accepted at p < .05.
Results Results from the tests for peak V0 2 indicated the arm crank peak V0 2 averaged approximately 72% ofthe value achieved during cycling. This value is consistent with the reported value of 73%, which represents the difference between upper and lower body peak V0 2 when averaged across a minimum of 18 previously reported studies (Sawka, 1986). Mean peak V0 2 was 1.94 ± 0.57 L'mirr' (27.0 ± 4.4 ml-kgl-rnin") for the arm crank and 2.68 ± 0.73 Lvmirr' (37.4 ± 5.7 ml-kgl-rnirr') for the cycle ergometer. Peak HR averaged 186.1 ± 9.7 and 188.4 ± 9.7 b-rnirr' for the upper body and lower body exercises, respectively. A description of the physiological status of the subjects during the baseline period of each experimental condition is shown in Table 1. Mean values for V02 , HR, RER, and energy expenditure indicate the subjects were in a comparable resting state for each experimental condition.
Table1. Description ofthe physiological status ofthe subjects (N= 8)during the baseline periodpreceding arm crank and cycle ergometry Variable Oxygen uptake (Lmirr') Oxygen uptake (ml.kg"min") Hear! rate [b-min"] Respiratory exchange ratio Energy expenditure [kcal-rnirr']
Arm Crank 0.26 ± 0.06 3.59 ± 0.27 67.40 ± 9.30 0.89 ± 0.03 1.28 ± 0.29
Cycle 0.24 3.41 68.40 0.91 1.24
± ± ± ±
0.05 0.23 9.70 0.03 ± 0.29
Note. Values represent M± SO.
RQES: June 1991
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Sedlock
Exercise V0 2 averaged 1.18± 0.34 L'mirr' during the arm crank exercise and 1.63 ± 0.47 Lvmin" during cycling. This represented 60.7 ± 1.19% and 60.3 ± 2.26% of the mode-specific peak V0 2, respectively. Mean HR was 136.9± lfi.Sb-rnirr' during arm cranking and 137.3±13.7 b-mirr' during cycling. RERaveraged 1.02±0.08and 1.02 ±0.04duringupperandlowerbodyexercise, respectively. Mean values for data obtained during the EPOC period are presented in Table 2. Neither the arm crank nor the cycle ergometer exercise produced a prolonged EPOC response. Additionally, there was no significant difference in the duration of EPOC between the two experimental conditions (t [7] = 0.24, p » .05). Magnitude of EPOC was small and not significantly different following the upper and lower body exercises (t [7] = 0.69, p » .05). The two experimental conditions also had no differential effect on HR or RER at the end of the EPOC period.
Discussion This study was designed to investigate the magnitude and duration of EPOC following upper body exercise, using lower body exercise for comparison. Results indicate the EPOC responses to moderate intensity arm crank and cycle ergometer exercise were not significantly different when the exercises were performed at a comparable relative metabolic intensity. Moreover, these results occurred despite a 28% lower absolute metabolic rate and exercise energy expenditure during arm crank than cycle ergometer exercise. To date, lower body exercise has been employed in the literature focused on examining the magnitude and duration of EPOC. In this regard, it has been suggested EPOC may be related to the magnitude of the disturbance to the body's resting homeostasis (Brehm & Cutin, 1986), especially since lower body exercise utilizes a large proportion of the body's skeletal muscle mass. Brehm and Cutin (1986) have proposed a model showing that recovery V0 2
Table2. Mean (±SO) values for excess postexercise oxygen consumption following arm crank and cycle ergometer exercise (N=8)
Variable
Arm Crank
Duration (min) Magnitude" (kcal) Heartrate" (b-mirr'] Respiratory exchange ratio'
22.9 9.2 78.8 0.88
± 13.7 ± 3.3 ± 12.3 ± 0.05
Cycle 24.2 10.4 76.3 0.90
± 19.4 ± 5.8 ± 10.2 ± 0.05
t*
0.24 0.69 1.03 1.21
" Sum ofthe net caloric expenditure for each minute ofthe excess postexercise oxygen consumption period. b Values measuredatthe end ofthe excess postexercise oxygen consumption period. * p » .05 for allvariables.
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increases in a curvilinear manner as a function of relative (to maximum) exercise intensity. This model is based on EPOC responses to treadmill walking and running. Results of the present study can be viewed within the context of the model proposed by Brehm and Cutin (1986). The exercise conditions of this study were not performed atseveral differentmetabolic intensities, since it was not the intent to determine the shape ofthe EPOC curve for upper body exercise as a function of relative intensity. However, since both upper body and lower body exercise were performed at the same percentage of peak V0 2 and elicited comparable EPOC responses, it could be suggested, within the context of the present research design, that EPOC may be related primarily to the relative (to maximum) perturbation to the exercising muscle mass rather than to the overall magnitude of the disturbance to the body's resting homeostasis. It could also be postulated this would occur regardless of the absolute metabolic rate, since this value was significantly different for the arm crank and cycle exercises of this study. Additionally, it might be suggested the EPOC response is independent of the quantity of muscle mass involved in upper versus lower body exercise, since this also differs for these exercise modes. Other researchers have also suggested exercise intensity is one ofthe primary factors governing the EPOC response (Knuttgen, 1970; McMiken, 1976). However, it seems this hypothesis is limited in scope since itis drawn from studies using lower body exercise exclusively. In this regard the present investigation, which employed a different quantity of muscle mass and absolute metabolic rate during exercise, adds unique support for this hypothesis. However, this is the first study to examine EPOC following upper body exercise. Therefore, much more research is needed to examine these issues. The two exercise conditions used in this study did not elicit a prolonged EPOC. These results support others who report the absence of a prolonged EPOC following moderate intensity exercise of a similar duration (Brehm & Cutin, 1986; Freedman-Akabas, Colt, Kissileff, & Pi-Sunyer, 1985; Pacy, Barton, Webster, & Carrow, 1985; Sedlock et al., 1989). An exercise intensity of 70% V0 2 max has been suggested as a threshold level necessary to produce a prolonged EPOC (Brehm, 1988). However, it seems other (as yet unidentified) factors are involved in producing a protracted EPOC. Thatis, exercise intensities of 70% V0 2 max or greater have been reported to both elicit (Bahr et al., 1987; Maehlum et aI., 1986) and fail to produce (Kaminsky, Kanter, Lesmes, & Laham-Saeger, 1987; Sedlock et aI., 1989) a lengthy EPOC period, whereas lower intensity (50% V0 2 max) longer duration exercise has been shown to result in a prolonged EPOC (Bielinski, Schutz, &Jequier, 1985). The findings ofthis study indicate the EPOCresponse following moderate intensity upper body exercise was similar to that of lower body exercise when the exercise
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was performed at equivalent relative metabolic rates. Within the limitations of the experimental design, these results suggest postexercise energy expenditure following moderate intensity exercise may be related primarily to the relative metabolic rate ofthe active musculature, as opposed to the absolute rate of exercise energy expenditure or quantity ofactive muscle mass involved in these two modes of exercise. Future work should be directed toward exploring these issues, in addition to examining the EPOC response to a variety of exercise intensity/ duration combinations.
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