The aim of the study was to follow up changes in physiological responses to incremental exercise after 4 weeks of moderate-intensity training in overweight men. Prior to the training, all subjects underwent 2 identical control tests (C1 and C2). Each test included three treadmill running exercises, starting at the treadmill speed of 4 km/h, and increased by 1 km/h at the end of each 4 min stage. The same protocol was repeated after 4 weeks of training (T1). The subjects’ body mass index was not changed after the training. Heart rate, oxygen uptake and blood pressure were significantly reduced in C2 as compared with C1 test. After 4 weeks of training the respiratory frequency (Rf), was lower than that in the C2 but a significant difference was noted only at the running speeds of 4 and 6kmhr-1 (P<0.04). Tidal volume (TV) increased after training in comparison with C2. A significant difference was found at the running speeds of 5 and 6 km/h (P<0.03 and P<0.04, respectively). Minute ventilation (VE) was not significantly different between the tests. The present study showed that in obese subjects 4 weeks of moderate uncontrolled walking training is advantageous for changes in the respiratory pattern. However, it is too short for the cardiovascular adaptation and body weight loss. Familiarization of the subjects with the experimental procedure diminished activation of the sympathetic nervous system and has a important role for the results interpretation

B  Kruk

H  Pekkarinen

O  Hanninen

The aim of the study was to follow up changes in physiological responses to incremental exercise after 4 weeks of moderate-intensity training in overweight men. Prior to the training, all subjects underwent 2 identical control tests (C1 and C2). Each test included three treadmill running exercises, starting at the treadmill speed of 4 km/h, and increased by 1 km/h at the end of each 4 min stage. The same protocol was repeated after 4 weeks of training (T1). The subjects’ body mass index was not changed after the training. Heart rate, oxygen uptake and blood pressure were significantly reduced in C2 as compared with C1 test. After 4 weeks of training the respiratory frequency (Rf), was lower than that in the C2 but a significant difference was noted only at the running speeds of 4 and 6kmhr-1 (P<0.04). Tidal volume (TV) increased after training in comparison with C2. A significant difference was found at the running speeds of 5 and 6 km/h (P<0.03 and P<0.04, respectively). Minute ventilation (VE) was not significantly different between the tests. The present study showed that in obese subjects 4 weeks of moderate uncontrolled walking training is advantageous for changes in the respiratory pattern. However, it is too short for the cardiovascular adaptation and body weight loss. Familiarization of the subjects with the experimental procedure diminished activation of the sympathetic nervous system and has a important role for the results interpretation

Directory of Open Access Journals

Biology of Sport, Vol. 20 No4, 2003  .  RESPIRATORY  RESPONSE  TO  WALKING  TRAINING  IN OVERWEIGHT MEN  B.Kruk1, H.Pekkarinen2, O.Hanninen2 1Dept.  of  Applied  Physiology,  Medical  Research  Centre,  Polish  Academy  of Sciences, Warsaw, Poland; 2Dept. of Physiology, University of Kuopio, Kuopio, Finland   Abstract.  The  aim  of  the  study  was  to  follow  up  changes  in  physiological responses to incremental exercise after 4 weeks of moderate-intensity training in overweight men. Prior to the training, all subjects underwent 2 identical control tests (C1 and C2). Each test included three treadmill running exercises, starting at the treadmill speed of 4 km/h, and increased by 1 km/h at the end of each 4 min stage. The same protocol was repeated after 4 weeks of training (T1). The subjects’ body mass index was not changed after the training. Heart rate, oxygen uptake and blood pressure were significantly reduced in C2 as compared with C1 test. After 4 weeks of training the respiratory frequency (Rf), was lower than that in the C2 but a significant  difference  was  noted  only  at  the  running  speeds  of  4  and  6kmhr-1 (P<0.04). Tidal volume (TV) increased after training in comparison with C2. A significant difference was found at the running speeds of 5 and 6 km/h (P<0.03 and P<0.04,  respectively).  Minute  ventilation  (VE)  was  not  significantly  different between the tests. The present study showed that in obese subjects 4 weeks of moderate  uncontrolled  walking  training  is  advantageous  for  changes  in  the respiratory pattern. However, it is too short for the cardiovascular adaptation and body weight loss. Familiarization of the subjects with the experimental procedure diminished activation of the sympathetic nervous system and has a important role for the results interpretation.                                           (Biol.Sport 20:281-288, 2003)   Key words: Breathing pattern - Aerobic training - Familiarization                                                                 Reprint request to: Dr Barbara Kruk, Dept. Applied Physiology, Medical Research Centre, Polish Academy of Sciences, Pawińskiego 5, 02-106 Warsaw, Poland E-mail: kruk@cmdik.pan.pl                                                                                                         B.Kruk et al. Biol.Sport 20(4), 2003   282 Introduction    Regular physical exercise is one of the most important recommendations in treatment of obesity and it appears to be one of the major factors determining the long-term success in the weight loss programs [4,5} An inverse relationship was found  between  the  amount  of  daily  physical  activity  and  body  mass  [13]. Unfortunately, from two thirds of over-weight persons trying to lose weight using physical activity as a strategy for weight loss, only one fifth reported to be active at the  recommended  levels  [12].  Overweight  subjects  often  find  the  exercise prescription difficult to follow, since they get extremely tired, while walking at the pace  recommended  by  doctors  [11],  since  the  energetic  cost  of  their  work  is enhanced  in  comparison  with  leaner  subjects  [8,13].  At  comfortable  pace  the normal-weight subjects reach approx. 35% VO2max, whereas the obese ones as much as 56% VO2max [1]. Moreover, in obese subjects breathing frequency is higher, and their tidal volume lower than in lean subjects [17]. Therefore, the low-intensity weight loss programs, resulting in a slow but steady body mass reduction, seems to be more effective than the more intensive exercise [16].    The  aim  of  this  investigation  was  to  follow  up  changes  in  physiological responses  to  a  very  early  phase  of  moderate-intensity  training  programs  in overweight men. For this purpose, the cardiovascular and respiratory responses to incremental treadmill exercise were controlled before and after training. To find out whether familiarization with the laboratory testing procedure has any influence on the investigated variables, two control treadmill tests were performed.   Material and Methods     Subjects:  Twenty  four  moderately  obese  subjects,  not  participating  in  any regular physical activity or sport, gave their written informed consent to participate in this study. The project was approved by the Ethics Committee of the Kuopio University (Finland). The physical characteristics (mean±SD) of the subjects were: age - 45.7±7.0 years, body mass - 90.9±9.4 kg, and height - 177.9±6.9 cm.    Experimental  procedure:  The  subjects  were  submitted  to  4  weeks  of uncontrolled, moderate-intensity walking training program (without any changes in their usual diet) consisting of 45 min daily walk, at the heart rate of 130 beats/min. An  accuracy  of  recommended  training  was  controlled  only  by  the  subjects themselves.  Prior  to  the  training,  all  subjects  underwent  2  identical  control exercise  tests  2-3  days  apart  (C1  and  C2).  Each  test  included  three  treadmill running exercises, starting at the treadmill speed of 4 km/h, and increased by 1 Respiratory response to walking training in overweight men Biol.Sport 20(4), 2003   283 km/h at the end of each 4 min stage. During all tests the respiratory gas exchange was analyzed continuously with Oxycon 4 (Mijnhardt) and computed every 30 s. Besides, the tidal volume (TV), respiratory frequency (Rf) and minute ventilation (VE) were recorded. Heart rate (HR) was measured using Sport Tester (PE 3000, Oulu,  Finland)  before  and  during  the  whole  test.  Blood  pressure  (BP)  was measured before and after termination of the test by auscultation method. The rate of perceived exertion (RPE) was registered at the end of each running speed. The same  protocol  was  repeated  with  the  subjects  after  4  weeks  of  training  (T1). Before  the  C1  and  T1  tests  the  anthropometric  measurements  were  made, including height (H), body mass (M), and thickness of four skin-folds (biceps, triceps, sub-scapular and abdominal) on the left body side.   Statistics: Statistical significance of differences was compared by depended t test of means. Significance was set at the P<0.05 level of confidence. All data are reported as meansSE.  Results     Body mass index and body fat percentage: The subjects’ body mass index was maintained on a similar level during the whole experimental period and it was: 28.90.5 and 28.70.5 (N.S.) before and after the training, respectively. Similarly, no differences were found in their body fat percentage. These values varied from 24.4±0.6 % before training to 24.5±0.6 % after it (N.S.).   Physiological variables (Fig. 1):  Heart rate (HR). At each successive running speeds HR was significantly lower in C2 than in C1 (P<0.01, P<0.01 and P<0.03, respectively).   Oxygen uptake (VO2). In the first two of running speeds (4 and 5 kmhr-1), VO2 was  significantly  reduced  in  C2  in  comparison  with  C1  (P<0.01  and  P<0.02, respectively). This tendency P<0.09) was maintained to the end of the test.   Respiratory quotient (RQ) was significantly lower in the C2 than in C1 test but only at the running speed of 4 kmhr-1 (P<0.03).   Respiratory frequency (Rf) During the C2 test, Rf was significantly decreased in comparison  with  C1  at  each  running  speed  (P<0.01,  P<0.004  and  P<0.003, respectively). After 4 weeks of training Rf, decreased further and it was lower than that in the C2 at the running speeds of 4 and 6kmhr-1 (P<0.04).   Tidal volume (TV) was similar in two control tests (C1 and C2). After training it increased and a significant difference was found at the running speed of 5 and 6 km/h (P<0.03 and P<0.04, respectively).                                                                                                          B.Kruk et al. Biol.Sport 20(4), 2003   284  Respiratory response to walking training in overweight men Biol.Sport 20(4), 2003   285 Fig. 1 Mean values (SE) of heart rate (HR), oxygen uptake (VO2), respiratory exchange ratio (RER), respiratory frequency (Rf), tidal volume (TV) and minute ventilation (VE) in 24 subjects performing 3 graded incremental tests on the treadmill; The first control test (C1) - open circles; the second control test (C2) – close circles; after training (T1) – squares.  *Significance  differences  between  C1  and  C2  tests; +Significant  differences between C2 and T1 tests     Minute ventilation (VE) was lower in C2 than that in C1 at the first running speeds (4 kmhr.-1).   Mean  arterial  blood  pressure  (MAP).  Under  resting  conditions  MAP  was significantly lower in C2 than in C1 test (109.7±2.5 mmHg vs.114.5±3.1 mmHg, P<0.01). Similarly, after exercise MAP values were lower in C2 than in C1 test (111.6±2.8 mmHg and 116.2±3.2 mmHg, P<0.02). As compared to C2 the training did not change either the resting or the exercise induced changes in MAP.   Perceive  exertion:  The  subjects’  subjective  rating  of  perceive  exertion (measured  by  Borg’s  scale)  tended  to  be  diminished  from  test  to  test.  At  the running speed of 5 kmhr-1 it significantly decreased from 10.70.4 points in the C1 test to 10.10.4 points in the C2 test (P<0.05). This tendency was also evident after training (P<0.07).   Discussion    It  was  found  that  the  earliest  and  most  prominent  effect  induced  by  the moderate-intensity  training  applied  in  the  present  study  were  changes  in  the breathing pattern. After training the breathing frequency of the subjects decreased, while  tidal  volume  increased  at  the  similar  minute  ventilation.  Thus,  after  the training  the  subjects  could  breath  in  the  way  more  similar  to  leaner  person, although their body mass did not be change. Such advantageous changes in the breathing pattern after a short-lasting training seem important because it is known, that in obesity the relationships between the lungs, chest walls, and diaphragram are disadvantageous for respiratory function [2,3]. Markov et al. [10] found that in healthy  men  the  respiratory  muscle  training  improves  breathing  and  cycling similarly  to  the  effects  observed  after  endurance  training.  The  above  authors suggested that these changes were not due to cardiovascular adaptation but that fatigue  of  the  respiratory  muscles  might  have  been  reduced  by  their  training,                                                                                                         B.Kruk et al. Biol.Sport 20(4), 2003   286 allowing the subjects to cycle for longer time. In the light of these results our finding  seems  very  interesting  because  we  have  found  that  walking  endurance training in obese subjects improves their respiratory functions. Moreover, it can be assumed that the improvement in the subjective rating of perceive exertion could have a psychological meaning stimulating the obese subjects for continuation of the training, the more so as the some obese subjects have a poor adherence to prescribed exercise [5,6].   It  should  be  emphasized  that  other  physiological  variables  measured  in  our study  did  not  change  significantly  during  4  weeks  of  training.  However,  these results have delivered some proofs concerning the importance of familiarization with exercise testing procedure for valuation of early effects of training. In our previous study [18] it was hypothesized that familiarization might reduce intra-individual  variability of some physiological responses because of physiological stress limitation. Our conclusion was based on the observation, that the early post-training  decrease  in  HR  might  be  due  to  familiarization  of  subjects  to  the experimental protocol. Thus, the lack of the second control in the above mentioned study could change interpretation of our training effects. Similarly, in the present investigation,  oxygen  uptake,  BP  and  HR  responses  to  the  treadmill  test  were significantly attenuated during the 2nd control test in comparison with the 1st one. Since after 4 weeks of walking training, these responses were similar to those found in the 2nd control test it seems justified to suggest that the uncontrolled walking  training  by  itself  does  not  affect  the  above  mentioned  variables. Therefore, it may be assumed that familiarization with the experimental procedure causes attenuation of HR and BP responses to the treadmill test, probably though the lesser activation of the sympathetic nervous system already during the second control test. We consider that there is a similarity between exercise- and mental-induced stress in reactivity of HR and BP [9]. A transient sympathetic arousal in response to the mental stress, characterized by excessive reactions to the stress were described by many authors. [7,9,14].    Summarizing.  The  present  study  showed  that  in  obese  subjects  4  weeks  of moderate  uncontrolled  walking  training  is  advantageous  for  changes  in  the respiratory pattern. Familiarization of the subjects with the experimental procedure diminished activation of sympathetic nervous system and has a important role for the results interpretation.     Respiratory response to walking training in overweight men Biol.Sport 20(4), 2003   287 References    1. Astrand P.O., K.Rodahl (1986) Textbook of work physiology. Physiological bases of exercise. McGraw-Hill, New York, pp 1-756   2. Babb T.G., D.Korzick, M.Meador, J.L.Hodgson, E.R.Buskirk (1991) Ventilatory response of moderately obese women to submaximal exercise. Int.J.Obesity 15:59-65   3. Babb T.G., D.S.DeLorey, B.L.Wyrick, P.P.Gardner (2002) Mild obesity does not limit  change  in  end-expiratory  lung  volume  during  cycling  in  young  women.  J.Appl. Physiol. 92:2483-2490   4. Blaak E.E., W.H.Saris (2002) Substrate oxidation, obesity and exercise training Best Pract. Res.Clin.Endocrinol.Metab. 16:667-678   5. Borg P., K.Kukkonen-Harjula, M.Fogelholm, M.Pasanen (2002) Effects of walking or resistance training on weight loss maintenance in obese, middle-aged men: a randomized trial. Int.J.Obes.Relat.Metab.Disord. 26:576-583   6. Byrne N.M., A.P.Hills ((2002) Relationship between HR and VO2 in the obese. Med.Sci. Sports Exerc. 34:1419-1427   7. Everson S.A., J.W.Lynch, G.A.Kaplan, T.A.Lakka, J.Sivenius, J.T.Salonen. (2001) Stress-induced blood pressure reactivity and incident stroke in middle-aged men. Stroke 32:1263-1270   8. Hulens M., G.Vansant, R.Lysens, A.L.Claessens, E. Muls (2001) Exercise capacity in lean versus obese women. Scand.J.Med.Sci.Sports 11:305-309   9.  Kral  B.G.,  L.C.Becker,  R.S.Blumenthal,  T.Aversano,  L.A.Fleisher,  R.M.Yook, D.M.Becker  (1997)  Exaggerated  reactivity  to  mental  stress  is  associated  with  exercise-induced  myocardial  ischemia  in  an  asymptomatic  high-risk  population.  Circulation 96:4246-4253 10. Markov G., Ch.M.Spengler, C.Knopfli-Lenzin, Ch.S.Boutellier (2001) Respiratory muscle training increases cycling endurance without affecting cardiovascular responses to exercise. Eur.J.Appl.Physiol. 85:233-239 11. Mattsson E., U.E.Larsson, S.Rossner (1977) Is walking for exercise too exhaustiong for obese women? Int.J.Obes.Relat.Metab.Disord. 21:380-386 12. Pate R.R., M.Pratt, S.N.Blair, W.L.Haskell, C.A.Macera, C.Bouchard, D.Buchner, W.Ettinger,  G.W.Heath,  A.C.King,  et  al.  (1995)  Physical  activity  and  public  health.  A recommendation  from the Centers for Disease Control and Prevention and the American College of Sports Medicine.  JAMA 273:402-407 13. Poirier P.P., J-P.Despres (2001) Exercise in weight management of obesity. Cardiol. Clin. 19:459-470 14. Rozanski A., J.A.Blumenthal, J.Kaplan (1999) Impact of psychological factors on the  pathogenesis  of  cardiovascular  disease  and  implications  for  therapy.  Circulation 99:2192-2217                                                                                                         B.Kruk et al. Biol.Sport 20(4), 2003   288 15.  Wadden  T.A.,  G.D.Foster,  K.A.Letizia  (1994)  One-year  behavioral  treatment  of obesity; comparison of moderate and severe caloric restriction and the effects of weight maintenance therapy. J.Consult.Clin.Psychol. 62:165-171 16. Whipp B.J., J.A.Davis (1984) The ventilatory stress of exercise obesity. Am.Rev. Respir.Dis. 129 (Suppl.):590-592 17. Ziemba A.W., J.Chwalbińska-Moneta, H.Kaciuba-Uściłko, B.Kruk, K.Krzemiński, G.Cybulski,  K.Nazar  (2003)  Early  effects  of  short-term  aerobic  training.  Physiological responses to graded exercise. J.Sports Med.Phys.Fitness 43:57-63   Accepted for publication 4.07.2003  

Respiratory response to walking training in overweight men

Abstract

Similar works

Full text

Available Versions

Directory of Open Access Journals