Journal of Exercise Physiologyonline

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1 84 Journal of Exercise Physiologyonline August 2013 Volume 16 Number 4 Editor-in-Chief Official Research Journal of Tommy the American Boone, PhD, Society MBA of Review Exercise Board Physiologists Todd Astorino, PhD Julien Baker, ISSN PhD Steve Brock, PhD Lance Dalleck, PhD Eric Goulet, PhD Robert Gotshall, PhD Alexander Hutchison, PhD M. Knight-Maloney, PhD Len Kravitz, PhD James Laskin, PhD Yit Aun Lim, PhD Lonnie Lowery, PhD Derek Marks, PhD Cristine Mermier, PhD Robert Robergs, PhD Chantal Vella, PhD Dale Wagner, PhD Frank Wyatt, PhD Ben Zhou, PhD Official Research Journal of the American Society of Exercise Physiologists ISSN JEPonline Comparison of the Acute Cardiopulmonary Responses of Trained Young Men Walking or Running the Same Distance at Different Speeds on a Treadmill Marcelo de Castro Cesar 1, Márcio Antônio Gonsalves Sindorf 1, Luciano Antônio da Silva 1, Pamela Roberta Gomes Gonelli 1, Idico Luiz Pellegrinotti 1, Rozangela Verlengia 1, Maria Imaculada de Lima Montebelo 2, Fúlvia de Barros Manchado-Gobatto 3 1 Physical Education Course College of Health Science and 2 College of Exacts and Nature Science, Methodist University of Piracicaba, Piracicaba, São Paulo, Brazil, 3 University of Campinas, Limeira, São Paulo, Brazil ABSTRACT Cesar MC, Sindorf MAG, Silva LA, Gonelli PRG, Pellegrinotti IL, Verlengia R, Montebelo MIL, Manchado-Gobatto FB. Comparison of the Acute Cardiopulmonary Responses of Trained Young Men Walking or Running the Same Distance at Different Speeds on a Treadmill. JEPonline. 2013;16(4): The aim of this study was to compare the acute cardiopulmonary responses of men to walking and running the same distance at different speeds on a treadmill. Sixteen trained young men participated. All the volunteers underwent one maximal and two submaximal cardiopulmonary exercise tests. The submaximal tests covered a distance of two miles each, one walking at 3.0 miles h -1 for 40 min and the other 6.0 miles h -1 running for 20 min. The following variables were higher while running: oxygen uptake, carbon dioxide output, heart rate, oxygen pulse, pulmonary ventilation, and energy expenditure. No significant differences were found between running and walking for ventilatory equivalents for oxygen or carbon dioxide. The percentage of oxygen uptake reserve was 58.9 ± 5.2% for running and 18.5 ± 2.1% for walking. The findings indicate that running 2 miles is more efficient than walking for improving cardiorespiratory fitness in trained young men because running is associated with greater cardiopulmonary responses. Key Words: Walk, Run, Oxygen Uptake, Exercise

2 85 INTRODUCTION Regular physical exercise provides a number of health benefits (1,10,18,21). In particular, it reduces the risk of developing chronic diseases (5) and, therefore, lowers mortality rate and increases longevity (6,14). But, training programs for health-related physical fitness must be at a sufficient intensity to improve cardiorespiratory capacity (1). This point is important in that running is often necessary to increase intensity. While many people walk or run for exercise, it is common questioned when to begin one or the other. Running can be inappropriate for beginners, since they may not be ready for vigorous exercise. People who are physically inactive should begin an exercise program by walking according to their fitness level and switch to running later on (3). Nevertheless, questions remain about whether walking longer at a lower intensity or running for a shorter time at higher intensity is more effective at improving cardiorespiratory function and body composition. The American College of Sports Medicine (1) recommends that apparently healthy adults engage in moderate-intensity cardiorespiratory exercise training (40-59% oxygen uptake reserve, 64-76% maximal heart rate, 46-63% maximal oxygen uptake) for 30 min or more per day, or vigorous-intensity exercise training (60-89% oxygen uptake reserve, 77-95% maximal heart rate, 64-90% maximal oxygen uptake) for 20 min or more per day. By comparison, Swan and Franklin (16) reviewed 18 previous studies on healthy subjects and found that 45% oxygen uptake reserve (%VO 2 R) was a minimal effective training intensity for highly fit subjects (i.e., baseline VO 2 max >40 ml kg -1 min -1 ) and 30% for less fit subjects (i.e., baseline VO 2 max <40 ml kg -1 min -1 ). Previous studies comparing the energy expenditure in walking or running the same distance (4,9,11, 12,19,22) have reported that running involves greater energy expenditure than walking. However, to our knowledge, no studies have compared the acute cardiopulmonary responses of walking and running the same distance at different speeds. Thus, the aim of this study was to compare the acute cardiopulmonary responses of walking and running two miles on a treadmill in trained young men to help maximize the results obtained during physical training. METHODS Subjects This study included 16 healthy men, mean ± standard deviation (SD) age 26.2 ± 4.6 yrs, body weight 73.4 ± 7.1 kg, and height ± 5.1 cm. All subjects had been engaged in physical training for a minimum of 1 yr. After being informed of the potential risks associated with the study, the volunteers signed an informed consent form that had been previously approved by the Research Ethics Committee of the Methodist University of Piracicaba. They also completed a health history questionnaire before undergoing the tests. Procedures The subjects underwent one maximal and two submaximal cardiopulmonary treadmill exercise tests 24 to 72 hrs apart. All tests were performed in a temperature-controlled laboratory (22 C to 25 C) on an Inbrasport ATL treadmill. The cardiopulmonary variables were measured directly with a Medical Graphics VO2000 metabolic gas analyzer. Heart rate was monitored during the treadmill tests with a Polar Vantage NV telemetry system.

3 The subjects performed a maximal cardiopulmonary test on the treadmill using a continuous protocol that consisted of a warm-up of 3.7 miles hr -1 for 1 min followed by an initial load of 4.35 miles hr -1 for 2 min with an increase of 0.6 miles hr -1 in the load every minute up to 8.7 miles hr -1, which was then followed by an increase in grade of 2.5% per minute until exhaustion (17). Maximal oxygen uptake (VO 2 max) was determined according to previously described criteria (7,15). Anaerobic threshold was determined by the ventilatory method (16). The submaximal tests involved the same distance, but in two different modalities: walking and running. Eight of the subjects performed the first submaximal test in the walking mode and the second test in running mode, while the remaining eight did the opposite. Two miles were covered in the submaximal tests, one walking at 3.0 miles hr -1 for 40 min and the other running at 6.0 miles hr -1 for 20 min. The subjects were instructed to maintain a regular diet, to avoid strenuous exercise for at least 24 hrs before the tests and to not eat for at least 2 hrs prior their submaximal tests. The cardiopulmonary variables were measured for 5 min prior to submaximal exercise, throughout the exercise period, and during recovery until the oxygen uptake values returned to the pre-test levels, which concluded the data collection. The following cardiopulmonary variables were measured: oxygen uptake (VO 2 ), carbon dioxide output (VCO 2 ), heart rate (HR), oxygen pulse (VO 2 /HR), pulmonary ventilation (V E ), ventilatory equivalents for oxygen (V E O 2 ) and carbon dioxide (V E CO 2 ). The cardiopulmonary variables VO 2, HR, and V E were compared before each exercise session to determine each subject s pre-exercise condition. Moreover, VO 2, HR, and V E were compared during walking and running as a percentage of the same variables obtained at maximal effort during the maximal cardiopulmonary exercise test. Exercise energy expenditure (EE) was calculated by multiplying VO 2 values by the thermal equivalent of oxygen (13). It was expressed in kilocalories min -1 and kilocalories during a total of 40 min of walking and 20 min of running. Percentage of oxygen uptake reserve (16) was calculated using: %VO 2 R = (gross exercise VO 2 3.5)/(VO 2 max 3.5). Statistical Analyses The data were expressed as the mean ± SD. Data normality was assessed with the Shapiro-Wilk test. Walking and running data were compared using paired t-tests for variables that met parametric test assumptions. For variables not checked for parametric assumptions, the Wilcoxon test was used (23). The significance level was set P<0.05. The data were processed with SPSS 7.5 software. 86 RESULTS Table 1 shows the results of the maximal cardiopulmonary test. Anaerobic threshold speed was greater than 6 miles hr -1 for all subjects. Table 1. Data from the Maximal Cardiopulmonary Exercise Test (n = 16). Variables Mean ± SD Maximal oxygen uptake (ml kg -1 min -1 ) 53.8 ± 4.9 Maximal heart rate (beats min -1 ) 190 ± 10 Maximal pulmonary ventilation (L min -1 ) ± 10.5 Oxygen uptake at anaerobic threshold (ml kg -1 min -1 ) 37.0 ± 3.7 Heart rate at anaerobic threshold (beats min -1 ) 161 ± 12 Pulmonary ventilation at anaerobic threshold (L min -1 ) 71.3 ± 9.4 Speed at anaerobic threshold (miles hr -1 ) 6.9 ± 0.5

4 Table 2 shows a comparison of the cardiopulmonary responses for walking and running in the pretest condition. The results show no significant differences in the measured variables. During the postexercise session recovery, VO 2 returned to resting values in <10 min for both types. 87 Table 2. Mean ± SD and Statistical Comparison of the Cardiopulmonary Variables before Submaximal Exercises (n = 16). Variables Walking Running VO 2 (ml kg -1 min -1 ) 4.6 ± ± 1.1 HR (beats min -1 ) 68 ± ± 10 V E (L min -1 ) 9.8 ± ± 1.7 VO 2 oxygen uptake; HR heart rate; V E pulmonary ventilation. No significant differences were found (t-test; P>0.05). The following cardiopulmonary variables were found to be higher during running than walking: VO 2, VCO 2, and VO 2 /HR. No statistical differences between running and walking were found in V E O 2 and V E CO 2 (Table 3). The absolute VO 2, HR, and V E, and the percent of the maximal exercise intensity were higher while running than while walking (Table 4). Table 3. Mean ± SD and Statistical Comparison of the Cardiopulmonary Responses during Submaximal Exercises (n = 16). Variables Walking Running VO 2 (L min -1 ) 0.94 ± ± 0.10 ** VCO 2 (L min -1 ) ± 0.24 ** VO 2 /HR (ml beat -1 ) 10.9 ± ± 2.0 ** V E O ± ± 2.6 V E CO ± ± 2.4 VO 2 oxygen uptake; VCO 2 carbon dioxide output; VO 2 /HR - oxygen pulse; V E O 2 ventilatory equivalent for oxygen; V E CO 2 ventilatory equivalent for carbon dioxide. **P<0.01, significant difference between walking and running. Table 4. Mean ± SD and Statistical Comparison of the Absolute Cardiopulmonary Responses during the Submaximal Exercises, and in Relation to the Percent of the Maximal Exercise Intensity (n = 16). Variables Walking Running VO 2 (ml kg -1 min -1 ) W 12.8 ± ± 3.0 ** VO 2 % max (%) t 23.9 ± ± 5.0 ** HR (beats min -1 ) t 87 ± ± 14 ** HR % max (%) t 45.8 ± ± 5.6 ** V E (L min -1 ) t 22.0 ± ± 8.5 ** V E % max (%) t 17.1 ± ± 6.4 ** VO 2 oxygen uptake; HR heart rate; V E pulmonary ventilation. t t-test, W Wilcoxon test. **P<0.01, significant difference between walking and running.

5 Energy expenditure per minute of running (11.9 ± 1.2 kcal min -1 ) was higher (P<0.01) than that of walking (4.5 ± 0.5 kcal min -1 ). The energy expenditure for 20 min of running (236.6 ± 23.8 kcal min -1 ) was also higher (P<0.01) than for 40 min of walking (181.7 ± 18.4 kcal min -1 ). The percentage of oxygen uptake reserve was 58.9 ± 5.2% for running (with all results above 45%), and 18.5 ± 2.1% for walking (with all results below 30%). 88 DISCUSSION The comparison of the cardiopulmonary variables before the submaximal tests presented no significant differences. Thus, the pre-test conditions of the subjects were similar before engaging in the exercises. The VO 2 max values indicated that the subjects had either good or high maximal aerobic power (2) with an anaerobic threshold speed of more than 6.0 miles hr -1, which was expected in trained young men. Oxygen uptake was higher during running than walking, indicating greater aerobic overload, which provides a stimulus for improving cardiorespiratory fitness. Heart rate and oxygen pulse also were higher during running than walking. Higher heart rate and oxygen pulse levels suggest greater cardiovascular effort and/or peripheral oxygen extraction during running (20). Although the increased pulmonary ventilation observed during running indicates that a greater nonsignificant respiratory system overload occurred than during walking, it was nevertheless proportional to oxygen uptake and carbon dioxide output as shown by V E O 2 and V E CO 2. These results indicate that pulmonary ventilation was linked with metabolic requirements during running and walking. This finding was an expected result for exercises below the anaerobic threshold (20). Energy expenditure was higher while running than while during walking. This is a finding in keeping with other studies (4,9,11,12,19,22). Therefore, running 2 miles is more effective than walking 2 miles for improving body composition. The present study found acute cardiopulmonary responses higher during running than during walking. These findings are in agreement with Cesar et al. (8) who reported that running was associated with higher VO 2, VCO 2, HR, VO 2 /HR, and V E, and EE values in young healthy men than when walking at the same speed (4.35 miles hr -1 ). Interestingly, though, they also observed no significant differences between running and walking for V E O 2 and V E CO 2. The running values in the present study indicate that the exercise intensity involved moderate-tovigorous cardiorespiratory effort (1) with the %VO 2 R above 45% in all subjects. Therefore it is an effective training intensity for fitter subjects. On the other hand, the walking values indicate less than moderate-intensity with a VO 2 R of less than 30% (16). Walking fails to meet the ACSM s recommendation that apparently healthy adults engage in cardiorespiratory exercise training defined as 40-59% VO 2 R (1). CONCLUSIONS This study showed that, in trained young men, running 2 miles at 6.0 miles hr -1 is associated with higher oxygen uptake, carbon dioxide output, heart rate, oxygen pulse, pulmonary ventilation, and energy expenditure than walking 2 miles at 3.0 miles hr -1. Thus, running 2 miles is more efficient for the improvement of cardiorespiratory fitness that is likely to be associated with an increase in health and well-being.

6 89 ACKNOWLEDGMENTS We gratefully thank the National Council of Scientific and Technological Development (CNPq) and the Federal Agency for Support and Evaluation of Graduate Education (CAPES) for the scholarship funding as well as William F. Hanes for revising the English manuscript. Address for correspondence: Marcelo de Castro Cesar, Methodist University of Piracicaba - College of Health Science. Rodovia do Açúcar, Km 156, Piracicaba, São Paulo, Brazil, Phone (+55) ; FAX: (+55) ; maccesar@unimep.br REFERENCES 1. American College of Sports Medicine. Quantity and quality of exercise for developing and maintaining cardiorespiratory, musculoskeletal, and neuromotor fitness in apparently healthy adults: Guidance for prescribing exercise. Med Sci Sports Exerc. 2011;43: American Heart Association. Exercise Testing and Training of Apparently Healthy Individuals. A Handbook for Physicians. Dallas, New York: AHA, Barros Neto TL. Exercise, Health and Physical Performance. São Paulo: Atheneu, 1997, pp Bhambhani Y, Singh M. Metabolic and cinematographic analysis of walking and running in men and women. Med Sci Sports Exerc. 1985;1: Blair SN. Physical activity, physical fitness, and health. Res Q Exerc Sport. 1993;64: Blair SN, Kohl HW, Barlow CE, et al. Changes in physical fitness and all- cause mortality: A prospective study of healthy and unhealthy men. JAMA. 1995;273: Cesar MC, Borin JP, Gonelli PRG, Simões, RA, Souza TMF, Montebelo MIL. The effect of local muscle endurance training on cardiorespiratory capacity in young women. J Strength Condit Res. 2009;23(6): Cesar MC, Gonelli PRG, Seber S, Pellegrinotti IL, Montebelo MIL. Comparison of physiological responses to treadmill walking and running in young men. Gazz Med Ital Arch Sci Med. 2007;166(5): Fellingham GW, Roundy ES, Fisher AG, Bryce GR. Caloric cost of walking and running. Med Sci Sports Exerc. 1978;10: Franklin BA, Roitman JL. Cardiorespiratory adaptations to exercise. In Roitman JL. (Editor). ACSM s Resource Manual for Guidelines for Exercise Testing and Prescription. Baltimore: Williams & Wilkins; 1998, pp

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