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Journal of Sports Sciences Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/rjsp20
Perceived exertion and physiological economy of competition walking, ordinary walking and running a
Gunilla Ljunggren & Peter Hassmen
a
a
Department of Psychology , University of Stockholm , S-106 91, Stockholm, Sweden Published online: 14 Nov 2007.
To cite this article: Gunilla Ljunggren & Peter Hassmen (1991) Perceived exertion and physiological economy of competition walking, ordinary walking and running, Journal of Sports Sciences, 9:3, 273-283, DOI: 10.1080/02640419108729889 To link to this article: http://dx.doi.org/10.1080/02640419108729889
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, sublicensing, systematic supply, or distribution in any form to anyone is expressly
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Journal of Sports Sciences, 1991, 9, 273-283
Perceived exertion and physiological economy of competition walking, ordinary walking and running GUNILLA LJUNGGREN and PETER HASSMEN Downloaded by [University of Sunderland] at 18:34 01 January 2015
Department of Psychology, University of Stockholm, S-106 91 Stockholm, Sweden
Accepted 28 June 1990
Abstract Four competition walkers performed competition walking, ordinary walking and running on a treadmill on two different occasions. During the two walking modes, the subjects performed maximal tests. During running, the session was terminated at a heart rate of 150 beats m i n - l or an exertion rating - for either chest or leg - of 5 or higher. The tests commenced at 2.5 km h-1 and the velocity was increased by 2.5 km h-1 every 4 min. Measures of chest exertion and breathlessness, leg exertion, heart rate and blood lactate were taken every 4 min just prior to the velocity changes. The measured psychological and physiological variables were described by monotonously accelerating power functions with exponents around 2 for the perceptual variables at both walking modes. The heart rate growth for competition walking accelerated according to a function with an exponent of 1.7, which is lower than that for ordinary walking (2.0), but higher than that for running which is linear. No significant difference was found between maximal oxygen uptake when competition walking and running were compared. A second test was carried out so as to confirm the cross-over point for the heart rate curves in the two walking modes. The cross-over point for the two walking curves was determined to be at 8.6 km h - 1 . Keywords: Competition walking, walking, running, perceived exertion, VO2 max.
Introduction
Walking is probably the most easily accessible of all types of physical exercise, and often underestimated as a way to increase a person's overall level of fitness. It does not require any special equipment and it is easy to exercise for an extended period of time with relatively low intensity. A trained walker can, however, very easily reach fairly high exercise intensities. Competition walking is a variation of walking that provides excellent possibilities for increasing the intensity of exercise, thus making it potentially a highly demanding sport. One major advantage with competition walking over running is that it has a lower frequency of injuries. The strain on ligaments and joints is far less than for comparable running exercises. One example of this is the magnitude of the ground reaction forces, i.e. the force between the ground and the foot. When running, these forces are normally around three times bodyweight, whereas they hardly ever exceed two times bodyweight when walking (Payne, 1978; Rippe et al., 1986). 0264-0414/91 $03.00 + .12 © 1991 E. & F.N. Spon
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Regardless of the type of physical activity, the individual's own perception of exertion is a vital component in determining how hard the exercise intensity is. An underestimation of the exertion can lead to overstrain, something that can be risky in certain situations or for certain groups of the population, e.g. heart patients. Healthy people can also misjudge the intensity of the exercise, e.g. in hot or humid environments and during psychological stress. Consequently, it is important to study how the perception of exertion varies for different modes of physical exercise and compare this with objective data such as observations on heart rate and blood lactate. Studies of perceived exertion in relation to physical work have been performed since the late 1950s (e.g. Borg and Dahlstrom, 1959, 1960; Borg, 1962, 1973; see also reviews by Mihevic, 1981; Pandolf, 1983). Most studies have dealt with bicycle ergometer exercise, although an increasing number of studies have been conducted where motor-driven treadmills were used instead of, or in combination with, ergometer bicycles (e.g. Noble and Borg, 1972; Mihevic, 1981; Pandolf, 1983). In all studies with graded exercise tests, perceived exertion has been shown to increase according to positively accelerating functions (Borg, 1962). As regards competition walking, the physiological studies performed so far have mainly been descriptive (see, e.g. Forsberg and Lundin, 1975) or have focused on comparisons between the rate of oxygen consumption in runners and walkers (Menier and Pugh, 1968; Wyndham and Strydom, 1971). Some studies have also included heart rate and ratings of perceived exertion (Noble and Borg, 1972; Hagberg and Coyle, 1984). When comparing the increase of both physiological and perceptual variables during running and walking, cross-over points are usually found for the physiological variables at certain velocities (Menier and Pugh, 1968; Wyndham and Strydom, 1971; Noble and Borg, 1972; Hagberg and Coyle, 1984). The cross-over point for heart rate seems to be around 8-9 km h~ 1 , at which point running becomes the more efficient. A corresponding cross-over point for perceived exertion is, however, only rarely found (Hagberg and Coyle, 1984). For competition walking, psychophysical functions have never been determined. Hence the aim of this study was to describe the psychophysical functions obtained for chest exertion and breathlessness (henceforth in the text abbreviated to chest exertion), as well as for leg exertion. Also of interest were the functional increases in heart rate and blood lactate, which were also collected in this study as indices of physiological responses. A second goal was to compare the effectiveness of competition walking relative to ordinary walking and to find the eventual cross-over points for the psychophysical and physiological curves. Thirdly, a comparison was made between measurements of maximal oxygen uptake (VO2 max) for competition walking and running, thus making it possible to study how efficiently subjects perform competition walking compared to running, i.e. do subjects reach as high levels of VO2 max while competition walking as they do while running. Methods The study was conducted in two separate parts.
Parti Subjects. Four male competition walkers of Swedish national standard were paid to participate in this study. Their mean age was 26.8 + 8.4 years, height 177.5 + 3.5 cm and weight 68.3 ±4.6 kg.
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Apparatus. The tests were performed on a treadmill (Power Jog) with no inclination. A second treadmill, with the facility to change the inclination gradually, was used for determining maximal oxygen uptake (VO2 max). Both treadmills were calibrated just prior to the tests. Expired air was collected in Douglas bags, to be subsequently analysed according to standard procedures. Heart rate was calculated at all work rates from ECGs transmitted telemetrically from the subject and recorded continuously on a one-channel ECG machine. Finger-prick blood samples were taken for subsequent lactate analysis (Rydevik et ah, 1982; Karlsson et al., 1983). Ratings of chest and leg exertion were made on Borg's (1982) category-ratio scale (CR-10; see Fig. 1). 0
Nothing at all
0,5
Extremely weak
1
Very weak
2
Weak
3
Moderate
(just noticeable)
(light)
4 5
Strong
(heavy)
6
7
Very strong
o o
9 10
Extremely strong
•
Maximal
(almost max)
Fig. 1. Borg's category-ratio scale (CR-10).
Design and procedure. After detailed instructions, a written informed consent was obtained. Thereafter, the subjects were taught to use the CR-10 scale by applying it to a visual test measuring intensities of greyness. The four subjects were tested on two different occasions, separated by an average of 2 weeks. Two of the subjects were randomly assigned to perform competition walking on the first occasion and ordinary walking on the second occasion; the other two subjects were tested in the reverse order. Qn both occasions, the subjects 'warmed up' by running for a total of 5 min at 2.5 km h" 1 and 5 km h" 1 . Thereafter, the actual experiment started with running until the subjects' heart ra^e reached approximately 150 beats min" 1 or they showed an exertion rating - for either chest or leg - of 5 or higher. After completing the running part, the subjects received a 30-min rest before they commenced the competition or ordinary walking. The reason the subjects started with running was two-fold: first, so that the psychophysical and physiological functions obtained from competition and ordinary walking could be compared
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with those from running, and, secondly, to compare the running data from the two different occasions so as to ensure that the subjects' physical ability had not changed between the first and second test occasions. In all three exercise modes, the subjects started at 2.5 kmh" 1 with a subsequent increase of 2.5 k m h ' 1 every 4 min, with a 1-min rest between each successive change. While performing competition walking and ordinary walking, the subjects only stopped when they could continue no longer. The subjects' heart rates were recorded just prior to the ratings which were given during the last 20 s at each velocity. During the two walking modes (competition and ordinary walking), blood lactate samples were taken in the pauses between the exercise bouts. All of the measurements were also taken before the tests started as well as after the 30-min rest. At the end of the testing, when the subjects were close to their maximum, heart rate was registered continuously. The psychophysical ratings were given just prior to when they jumped off the treadmill and the blood lactate samples were taken immediately afterwards. At both test occasions, the subjects' maximal oxygen uptake (VO2 max) was measured using Douglas bags. This was done when the ordinary test session was finished and the subjects had recovered enough to perform a maximal test (after about 5 min). During this part of the test, the treadmill with variable inclinations was used. The inclination was increased gradually until the subjects were unable to continue. After the competition walking test, the VO2 max for competition walking was measured; after the ordinary walking test, the VO2 max for running was measured. Part 2 The study was enlarged (part 2) because there was a need for a better anchorage of the cross-over point between the heart rate curves for ordinary walking and competition walking. The results from part 1 included only one velocity after the cross-over point. To make sure that the apparent divergence after the cross-over point was not simply accidental, the study was enlarged in the manner now described. Subjects. The same four subjects that participated in part 1 also participated in part 2. On this occasion, their age, height and weight were 28.0+8.4 years, 177.5 + 3.5 cm and 67.5+4.0 kg respectively. Apparatus. A treadmill (Rodby RL 1400, calibrated just prior to the test) with no inclination was used. The subjects' heart rates were recorded using a heart rate meter (Sport Tester PE-3000). The ratings and blood lactate samples were obtained as for part 1. Design and procedure. The subjects received detailed instructions after providing a written informed consent. During this part of the study, the subjects performed both ordinary walking and competition walking on the same test occasion. Two of the subjects randomly started with ordinary walking, and then, after a 20-min rest, they continued with competition walking. The other two subjects performed the test in the reverse order. Before the test started, as well as after the 20-min rest period, the subjects 'warmed up' for 3 min at 5 km h ~* using the same walking mode as they were going to perform later. During ordinary walking, the velocities were 6, 8, 10 and 12kmh" 1 , and during competition walking, 6, 8, 10, 12 and 14 km h" 1 . The subjects walked for 4 min at each
Perceived exertion during competition walking
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velocity and had a 1-min break between each. The reason why there was one more velocity for competition walking than for ordinary walking was to have a better opportunity to confirm the heart rate functions for both competition walking and ordinary walking as obtained in part 1. If both the cross-over point and the functions were the same, this would confirm the findings of part 1. As in part 1, the heart rates were recorded just prior to the ratings and the blood lactate samples were taken during the breaks between the velocity increments. All measurements were also taken before the test started and after the 20-min rest period. Arithmetic means were used in all calculations in both parts 1 and 2.
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Results Part 1 The subjects performed ordinary walking up to 10 km h " 1 and competition walking up to 17.5 km h " 1 . The running trials were terminated at 15 km h ~* at which velocity the subjects' heart rates reached 150 beats min" 1 or they rated 5 or higher on the CR-10 scale. The comparisons made between the run parts did not reveal any significant differences either for heart rate or for the ratings of leg and chest exertion between the two test occasions in part 1. The relations between heart rate and velocity were linear. On none of the test occasions were there any significant differences between the pre-test values and the values recorded after the 30-min rest period for ratings, heart rate or blood lactate. Concerning chest and leg exertion, there were no significant differences between the two walking modes and running below 7.5 km h " 1 (standard analysis of variance procedures). At higher velocities, however, the curves for the two walking modes accelerated more than the running curves. The chest and leg exertion curves for competition and ordinary walking followed each other closely (Fig. 2). The chest exertion function for competition walking was i?=0.7 + 1.601 • 10~ 2 • S 2 - 1 (rxy = 0.955) and for ordinary walking ^ = 0 . 6 + 1.213 • 10 ~2 • S21 (rxy=0.986). The corresponding functions for leg exertion were i?=0.9 + 3 . 6 0 6 - 1 0 - 2 S 1 9 ( ^ = 0 . 9 9 8 ) and 7?= 1.0+1.017 • 10" 2 • S2A (rx, = 0.994) respectively. The subjects' heart rates were higher for running than for either of the two walking styles up to 8.2 km h ~ *. At this velocity, the curves for running and competition walking cross each other. The cross-over point between running and ordinary walking can be found at 8.5 km h " 1 (Fig. 3). At 8.8 km h " 1 , the two walking curves cross each other. There is, however, only one common velocity level after the cross-over point between the walking curves. This point is studied further in part 2. The heart rate (HR) increment during competition walking is expressed by HR = 59 + 1.181 • Si/J (^=0.999). The corresponding function obtained for ordinary walking is HR = 57+ 0.607 • S20 (rxy=0.999). The blood lactate curves for ordinary walking and competition walking are mainly parallel, although at slightly different levels, up to the point where the subjects finished ordinary walking (Fig. 4). Above that point (10 km h~ 1 ), the curve for competition walking starts to accelerate. The blood lactate curve for ordinary walking is best described using linear regression (Y= 1.999 • 10~ 3 • x +1.3; rX), = 0.674). In order to describe the increase of competition walking there is a need for a b-value (Borg, 1962, 1973). The function is: R= 1.79 + 9.883 • 10" 3 • (S-9)30 (r, =0.999).
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DC
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o
CC
o
109876543210 10" 9876543212.5
5.0
12.5 15.0 17.5 7.5 10.0 1 h " ) Velocity (km Fig. 2. Perceived chest exertion and breathlessness (Chest) as well as leg exertion (Leg) during part 1, measured with Borg's CR-10 scale for running (on the two separate test occasions, Run 1 and Run 2), ordinary walking (OW) and competition walking (CW). 0.0
A comparison between the measurements of VO2 max does not reveal any significant differences between competition walking and running. However, the data for one of the subjects show that while race walking he used less than 90% of his VO2 max observed during running (see Table 1). Part 2
In part 2, the maximal velocities were set to 14kmh - 1 for competition walking and 1 2 k m h - 1 for ordinary walking. The results confirm the findings from part 1, with a cross-over point for heart rate between ordinary walking and competition walking at 8.6 km h" 1 (Fig. 5). Concerning chest and leg exertion, as well as blood lactate, no corresponding cross-over
Perceived exertion during competition walking
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2004T 180.E 160 i
1 140 H 2 120 H 1008060Downloaded by [University of Sunderland] at 18:34 01 January 2015
4020
0.0
2.5
5.0
7.5 10.0 12.5 15.0 17.5 Velocity (km h~ 1 ) Fig. 3. Heart rate (beats min"1) during part 1 for running (on the two separate test occasions, Run 1 and Run 2), ordinary walking (OW) and competition walking (CW).
8OWI OW II CWI
7o E E.
6543-
o m
210.0
2.5
5.0
7.5 10.0 12.5 15.0 17.5 Velocity (km h " 1 ) Fig. 4. Blood lactate during part 1 for ordinary walking (CW I) and competition walking (CW I) and during part 2 for ordinary walking (OW II). points are found. Nor are there any significant differences between the growth of the curves when comparing competition and ordinary walking. The heart rate functions found in part 2 are very much the same as in part 1. For competition walking, the function is R = 57 +1.4057 • S1"7 ( ^ = 0.998) and for ordinary walking #=57+0.5512 • S 2 1 ( ^ = 0.999). During ordinary walking, there was no increase in blood lactate in part 1. In part 2, where 1 2 k m h " ' was included, the function expressing the accumulation of blood lactate is # = 0.92 + 1.6912 • 10 ~ 5 • S 4 - 8 (rx =0.977) (see Fig. 4).
280
Ljunggren and Hassmen Table 1. VO2 max values obtained during running and competition walking (n = 4) Running Subject
1
^ O 2 max
ml k g " min"
1 2 3 4
5.3 3.7 4.5 4.8
74.0 60.3 67.0 66.4
4.7 3.5 4.6 5.0
64.9 56.6 69.2 70.3
X
4.6 0.7
66.9
4.5 0.7
65.3
S.D.
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Competition walking 1
VO2 max
5.6
ml kg * min
1
6.2
180" •
160" c
I
— ow C W
140"
(3 120100-
** w
CO
r0>
80-
*^
60ACl .
4
5
6
7
8
9
10
1 1 1 2 1 3
14
Velocity (km h" 1 ) Fig. 5. The cross-over point for heart rate determined in part 2 between competition walking (CWII) and ordinary walking (OW II).
Discussion Because they were highly trained athletes, the subjects were able to perform ordinary walking at higher levels than non-athletes are usually able to (Menier and Pugh, 1968). However, in part 2, the subjects had some difficulty performing'ordinary walking'at 12 km h " 1 , and they sometimes oscillated between ordinary walking and competition walking. This might, of course, influence the results to a certain degree when comparing the two walking modes. To what extent and in what direction, however, is difficult to judge. As can be seen from the results, however, the growth functions for ordinary walking obtained in part 1 and part 2 respectively, as well as for competition walking, concerning both heart rate and the psychophysical variables, were very much the same on the two test occasions. The subjects were constantly reminded of the necessity to stick to 'ordinary walking' and for the most part they were able to do so. They also verified that it was quite a different feeling to walk ordinarily, as compared to competition walking, at 12 km h " 1 . This velocity is therefore included in the calculations.
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The two different parts of the test were performed with an interval of almost \\ years. The subjects' weight had not changed significantly between the two test occasions even if two of the subjects were a little less active in their training the second time. There were no significant differences between the subjects' heart rate levels in parts 1 and 2, neither for competition walking nor for ordinary walking. Additionally, the heart rate functions were almost identical. As for the two test sessions within each part, and the rest periods of 30 and 20 min, there were no significant differences between the pre-test values and the values recorded after the rest periods. This indicates that a sufficient physical recovery had taken place, before the second halves of the test sessions. The correspondence of the heart rate curves between parts 1 and 2 indicates that the strain was very much the same in the two parts of the test. As found earlier (e.g. Borg et al., 1987), heart rate for ordinary walking was increasing according to a squared function. Competition walking includes additional biomechanical techniques which allow the subjects to walk at faster speeds. The slightly lower exponent in the heart rate growth function for competition walking may reflect this. The exponent is found to be between those usually found for running and ordinary walking, but a little closer to the latter. It is interesting to note that the chest exertion growth function is almost the same for the two walking modes, although the level of exertion seems to be a little lower for ordinary walking (N.S.). This means that the strain on chest and breathing is about equal for both. Even the two leg exertion curves follow each other closely, but as can be seen on the exponents the ordinary walking curve accelerates a little faster. Bearing in mind the biomechanical limitations for ordinary walking at higher velocities, this faster acceleration is understandable. The straight line obtained for the blood lactate increase during ordinary walking in part 1 means that, for this group of trained athletes, the accumulation of blood lactate starts after 10 km h ~1. The exponent of the lactate growth function for competition walking obtained in part 1 was very much the same as that found for running in the study by Borg et al. (1987). Moreover, the exponent of the blood lactate function for ordinary walking in part 2 was almost identical to what has been found earlier for walking (Borg et al., 1987). The curves for competition and ordinary walking cross each other at 8.6 km h~ * and the ordinary walking curve starts to accelerate more than the competition walking curve. This indicates that at this velocity, competition walking becomes physiologically more economical than ordinary walking, which is the most economical means of motion at lower velocities. The difference between the two walking modes is, however, small. This cross-over point is of the same magnitude as that usually found for running and ordinary walking. This strengthens the assumption that ordinary walking becomes physiologically uneconomical as a mode of locomotion at about this velocity, which is also in accordance with earlier findings of cross-over points mainly between 8 and 9 km h" 1 (Menier and Pugh, 1968; Noble and Borg, 1972; Hagberg and Coyle, 1984; Borg et al, 1987). The results also point to the great similarity between competition walking and running concerning efficiency during motion. The comparison between the values of maximal oxygen uptake revealed no significant difference between running and competition walking. The results also indicate a close similarity in the economy of locomotion of competition walking and running. This is in accordance with the findings of Hagberg and Coyle (1984) who found that VO2 max was the same during competition walking as during running among eight competition walkers. In conclusion, this study shows that the variables measured can be described by monotonically accelerating power functions for competition and ordinary walking. For
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competition walking, the chest and leg exertion functions have the exponents 2.1 and 1.9 respectively. The heart rate growth function accelerates with the exponent 1.7, and blood lactate with 3.0. With this last function, there is also a need for a b-value, meaning that the curve does not start to accelerate immediately. Furthermore, the study shows that competition walking becomes a more economical way of locomotion than ordinary walking at velocities above 8.6 km h~ 1 . This finding resembles what is usually found for running and ordinary walking, which in various studies shows a cross-over point between 8 and 9 km h" 1 . Finally, the study shows that elite competition walkers are able to reach VO2 max values during competition walking as high as those during running. Acknowledgements This research was supported by grants 14/86 and 22/88 from the Swedish Sports Research Council. References Borg, G. (1962). Physical performance and perceived exertion. Studia Psychologica et Paedagogica, Series Altera, Investigationes XI, Lund. Borg, G. (1973). Perceived exertion during walking: A psychophysical function with two additional constants. Reports of the Institute of Applied Psychology, University of Stockholm, 39, 1-10. Borg, G. (1982). A category scale with ratio properties for intermodal and interindividual comparisons. In Psychophysical Judgment and the Process of Perception (edited by H. G. Geissler and P. Petzold), pp. 25-33. Berlin: VEB Deutscher Verlag der Wissenschaft. Borg, G. and Dahlstrom, H. (1959). Psykofysisk undersokning av arbete pa cykel-ergometer. Nordisk Medicin, 62, 1383-6. Borg, G. and Dahlstrom, H. (1960). The perception of muscular w o r k - a psychophysical study of short-time work on the bicycle ergometer. Publications of the Research Library, No. 5, Umea. Borg, G., van den Burg, M., Hassmen, P., Kaijser, L. and Tanaka, S. (1987). Relationships between perceived exertion, HR and HLa in cycling, running and walking. Scandinavian Journal of Sports Sciences, 9, 69-77. Forsberg, A. and Lundin, A. (1975). Idrottsfysiologi, G&ng. Trygg- Hansa, Report No. 15. Hagberg, J.M. and Coyle, E.F. (1984). Physiologic comparison of competitive racewalking and running. International Journal of Sports Medicine, 5, 74-7. Karlsson, J., Jacobs, I., Sjodin, B., Tesch, P., Kaiser, P., Sahl, O. and Karlberg, B. (1983). Semiautomatic blood lactate assay: Experiences from an exercise laboratory. International Journal of Sports Medicine, 4, 52-5. Menier, D.R. and Pugh, L.G.C.E. (1968). The relation of oxygen intake and velocity of walking and running, in competition walkers. Journal of Physiology, 197, 717-21. Mihevic, P.M. (1981). Sensory cues for perceived exertion: A review. Medicine and Science in Sports and Exercise, 13, 150-63. Noble, B. and Borg, G. (1972). Perceived exertion during walking and running. In Proceedings of the XVIIth International Congress of Applied Psychology, Vol. 1, pp. 387-92. Brussels: Editest. Pandolf, K.B. (1983). Advances in the study and application of perceived exertion. In Exercise and Sport Sciences Reviews (edited by R.L. Terjung), Vol. 11, pp. 119-58. Philadelphia: Franklin Institute Press. Payne, A.H. (1978). A comparison of the ground reaction forces in race walking with those in normal walking and running. In Biomechanics VI-A (edited by E. Asmussen and K. Jergensen), pp. 293-302. Baltimore, Md.: University Park Press.
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Rippe, J.M., Ward, A., Haskell, W.L, Freedson, P., Franklin, B.A. and Campbell, K.R. (1986). Walking for fitness. The Physician and Sportsmedicine, 14, 145-59. Rydevik, U., Nord, L. and Ingman, F. (1982). Automatic lactate determination by flow injection analysis. International Journal of Sports Medicine, 3, 47-9. Wyndham, C.H. and Strydom, N.B. (1971). Mechanical efficiency of a champion walker. South African Medical Journal, 45, 551-3.
Journal of Sports Sciences Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/rjsp20
Perceived exertion and physiological economy of competition walking, ordinary walking and running a
Gunilla Ljunggren & Peter Hassmen
a
a
Department of Psychology , University of Stockholm , S-106 91, Stockholm, Sweden Published online: 14 Nov 2007.
To cite this article: Gunilla Ljunggren & Peter Hassmen (1991) Perceived exertion and physiological economy of competition walking, ordinary walking and running, Journal of Sports Sciences, 9:3, 273-283, DOI: 10.1080/02640419108729889 To link to this article: http://dx.doi.org/10.1080/02640419108729889
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, sublicensing, systematic supply, or distribution in any form to anyone is expressly
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Journal of Sports Sciences, 1991, 9, 273-283
Perceived exertion and physiological economy of competition walking, ordinary walking and running GUNILLA LJUNGGREN and PETER HASSMEN Downloaded by [University of Sunderland] at 18:34 01 January 2015
Department of Psychology, University of Stockholm, S-106 91 Stockholm, Sweden
Accepted 28 June 1990
Abstract Four competition walkers performed competition walking, ordinary walking and running on a treadmill on two different occasions. During the two walking modes, the subjects performed maximal tests. During running, the session was terminated at a heart rate of 150 beats m i n - l or an exertion rating - for either chest or leg - of 5 or higher. The tests commenced at 2.5 km h-1 and the velocity was increased by 2.5 km h-1 every 4 min. Measures of chest exertion and breathlessness, leg exertion, heart rate and blood lactate were taken every 4 min just prior to the velocity changes. The measured psychological and physiological variables were described by monotonously accelerating power functions with exponents around 2 for the perceptual variables at both walking modes. The heart rate growth for competition walking accelerated according to a function with an exponent of 1.7, which is lower than that for ordinary walking (2.0), but higher than that for running which is linear. No significant difference was found between maximal oxygen uptake when competition walking and running were compared. A second test was carried out so as to confirm the cross-over point for the heart rate curves in the two walking modes. The cross-over point for the two walking curves was determined to be at 8.6 km h - 1 . Keywords: Competition walking, walking, running, perceived exertion, VO2 max.
Introduction
Walking is probably the most easily accessible of all types of physical exercise, and often underestimated as a way to increase a person's overall level of fitness. It does not require any special equipment and it is easy to exercise for an extended period of time with relatively low intensity. A trained walker can, however, very easily reach fairly high exercise intensities. Competition walking is a variation of walking that provides excellent possibilities for increasing the intensity of exercise, thus making it potentially a highly demanding sport. One major advantage with competition walking over running is that it has a lower frequency of injuries. The strain on ligaments and joints is far less than for comparable running exercises. One example of this is the magnitude of the ground reaction forces, i.e. the force between the ground and the foot. When running, these forces are normally around three times bodyweight, whereas they hardly ever exceed two times bodyweight when walking (Payne, 1978; Rippe et al., 1986). 0264-0414/91 $03.00 + .12 © 1991 E. & F.N. Spon
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Regardless of the type of physical activity, the individual's own perception of exertion is a vital component in determining how hard the exercise intensity is. An underestimation of the exertion can lead to overstrain, something that can be risky in certain situations or for certain groups of the population, e.g. heart patients. Healthy people can also misjudge the intensity of the exercise, e.g. in hot or humid environments and during psychological stress. Consequently, it is important to study how the perception of exertion varies for different modes of physical exercise and compare this with objective data such as observations on heart rate and blood lactate. Studies of perceived exertion in relation to physical work have been performed since the late 1950s (e.g. Borg and Dahlstrom, 1959, 1960; Borg, 1962, 1973; see also reviews by Mihevic, 1981; Pandolf, 1983). Most studies have dealt with bicycle ergometer exercise, although an increasing number of studies have been conducted where motor-driven treadmills were used instead of, or in combination with, ergometer bicycles (e.g. Noble and Borg, 1972; Mihevic, 1981; Pandolf, 1983). In all studies with graded exercise tests, perceived exertion has been shown to increase according to positively accelerating functions (Borg, 1962). As regards competition walking, the physiological studies performed so far have mainly been descriptive (see, e.g. Forsberg and Lundin, 1975) or have focused on comparisons between the rate of oxygen consumption in runners and walkers (Menier and Pugh, 1968; Wyndham and Strydom, 1971). Some studies have also included heart rate and ratings of perceived exertion (Noble and Borg, 1972; Hagberg and Coyle, 1984). When comparing the increase of both physiological and perceptual variables during running and walking, cross-over points are usually found for the physiological variables at certain velocities (Menier and Pugh, 1968; Wyndham and Strydom, 1971; Noble and Borg, 1972; Hagberg and Coyle, 1984). The cross-over point for heart rate seems to be around 8-9 km h~ 1 , at which point running becomes the more efficient. A corresponding cross-over point for perceived exertion is, however, only rarely found (Hagberg and Coyle, 1984). For competition walking, psychophysical functions have never been determined. Hence the aim of this study was to describe the psychophysical functions obtained for chest exertion and breathlessness (henceforth in the text abbreviated to chest exertion), as well as for leg exertion. Also of interest were the functional increases in heart rate and blood lactate, which were also collected in this study as indices of physiological responses. A second goal was to compare the effectiveness of competition walking relative to ordinary walking and to find the eventual cross-over points for the psychophysical and physiological curves. Thirdly, a comparison was made between measurements of maximal oxygen uptake (VO2 max) for competition walking and running, thus making it possible to study how efficiently subjects perform competition walking compared to running, i.e. do subjects reach as high levels of VO2 max while competition walking as they do while running. Methods The study was conducted in two separate parts.
Parti Subjects. Four male competition walkers of Swedish national standard were paid to participate in this study. Their mean age was 26.8 + 8.4 years, height 177.5 + 3.5 cm and weight 68.3 ±4.6 kg.
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Apparatus. The tests were performed on a treadmill (Power Jog) with no inclination. A second treadmill, with the facility to change the inclination gradually, was used for determining maximal oxygen uptake (VO2 max). Both treadmills were calibrated just prior to the tests. Expired air was collected in Douglas bags, to be subsequently analysed according to standard procedures. Heart rate was calculated at all work rates from ECGs transmitted telemetrically from the subject and recorded continuously on a one-channel ECG machine. Finger-prick blood samples were taken for subsequent lactate analysis (Rydevik et ah, 1982; Karlsson et al., 1983). Ratings of chest and leg exertion were made on Borg's (1982) category-ratio scale (CR-10; see Fig. 1). 0
Nothing at all
0,5
Extremely weak
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Moderate
(just noticeable)
(light)
4 5
Strong
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o o
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•
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Fig. 1. Borg's category-ratio scale (CR-10).
Design and procedure. After detailed instructions, a written informed consent was obtained. Thereafter, the subjects were taught to use the CR-10 scale by applying it to a visual test measuring intensities of greyness. The four subjects were tested on two different occasions, separated by an average of 2 weeks. Two of the subjects were randomly assigned to perform competition walking on the first occasion and ordinary walking on the second occasion; the other two subjects were tested in the reverse order. Qn both occasions, the subjects 'warmed up' by running for a total of 5 min at 2.5 km h" 1 and 5 km h" 1 . Thereafter, the actual experiment started with running until the subjects' heart ra^e reached approximately 150 beats min" 1 or they showed an exertion rating - for either chest or leg - of 5 or higher. After completing the running part, the subjects received a 30-min rest before they commenced the competition or ordinary walking. The reason the subjects started with running was two-fold: first, so that the psychophysical and physiological functions obtained from competition and ordinary walking could be compared
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with those from running, and, secondly, to compare the running data from the two different occasions so as to ensure that the subjects' physical ability had not changed between the first and second test occasions. In all three exercise modes, the subjects started at 2.5 kmh" 1 with a subsequent increase of 2.5 k m h ' 1 every 4 min, with a 1-min rest between each successive change. While performing competition walking and ordinary walking, the subjects only stopped when they could continue no longer. The subjects' heart rates were recorded just prior to the ratings which were given during the last 20 s at each velocity. During the two walking modes (competition and ordinary walking), blood lactate samples were taken in the pauses between the exercise bouts. All of the measurements were also taken before the tests started as well as after the 30-min rest. At the end of the testing, when the subjects were close to their maximum, heart rate was registered continuously. The psychophysical ratings were given just prior to when they jumped off the treadmill and the blood lactate samples were taken immediately afterwards. At both test occasions, the subjects' maximal oxygen uptake (VO2 max) was measured using Douglas bags. This was done when the ordinary test session was finished and the subjects had recovered enough to perform a maximal test (after about 5 min). During this part of the test, the treadmill with variable inclinations was used. The inclination was increased gradually until the subjects were unable to continue. After the competition walking test, the VO2 max for competition walking was measured; after the ordinary walking test, the VO2 max for running was measured. Part 2 The study was enlarged (part 2) because there was a need for a better anchorage of the cross-over point between the heart rate curves for ordinary walking and competition walking. The results from part 1 included only one velocity after the cross-over point. To make sure that the apparent divergence after the cross-over point was not simply accidental, the study was enlarged in the manner now described. Subjects. The same four subjects that participated in part 1 also participated in part 2. On this occasion, their age, height and weight were 28.0+8.4 years, 177.5 + 3.5 cm and 67.5+4.0 kg respectively. Apparatus. A treadmill (Rodby RL 1400, calibrated just prior to the test) with no inclination was used. The subjects' heart rates were recorded using a heart rate meter (Sport Tester PE-3000). The ratings and blood lactate samples were obtained as for part 1. Design and procedure. The subjects received detailed instructions after providing a written informed consent. During this part of the study, the subjects performed both ordinary walking and competition walking on the same test occasion. Two of the subjects randomly started with ordinary walking, and then, after a 20-min rest, they continued with competition walking. The other two subjects performed the test in the reverse order. Before the test started, as well as after the 20-min rest period, the subjects 'warmed up' for 3 min at 5 km h ~* using the same walking mode as they were going to perform later. During ordinary walking, the velocities were 6, 8, 10 and 12kmh" 1 , and during competition walking, 6, 8, 10, 12 and 14 km h" 1 . The subjects walked for 4 min at each
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velocity and had a 1-min break between each. The reason why there was one more velocity for competition walking than for ordinary walking was to have a better opportunity to confirm the heart rate functions for both competition walking and ordinary walking as obtained in part 1. If both the cross-over point and the functions were the same, this would confirm the findings of part 1. As in part 1, the heart rates were recorded just prior to the ratings and the blood lactate samples were taken during the breaks between the velocity increments. All measurements were also taken before the test started and after the 20-min rest period. Arithmetic means were used in all calculations in both parts 1 and 2.
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Results Part 1 The subjects performed ordinary walking up to 10 km h " 1 and competition walking up to 17.5 km h " 1 . The running trials were terminated at 15 km h ~* at which velocity the subjects' heart rates reached 150 beats min" 1 or they rated 5 or higher on the CR-10 scale. The comparisons made between the run parts did not reveal any significant differences either for heart rate or for the ratings of leg and chest exertion between the two test occasions in part 1. The relations between heart rate and velocity were linear. On none of the test occasions were there any significant differences between the pre-test values and the values recorded after the 30-min rest period for ratings, heart rate or blood lactate. Concerning chest and leg exertion, there were no significant differences between the two walking modes and running below 7.5 km h " 1 (standard analysis of variance procedures). At higher velocities, however, the curves for the two walking modes accelerated more than the running curves. The chest and leg exertion curves for competition and ordinary walking followed each other closely (Fig. 2). The chest exertion function for competition walking was i?=0.7 + 1.601 • 10~ 2 • S 2 - 1 (rxy = 0.955) and for ordinary walking ^ = 0 . 6 + 1.213 • 10 ~2 • S21 (rxy=0.986). The corresponding functions for leg exertion were i?=0.9 + 3 . 6 0 6 - 1 0 - 2 S 1 9 ( ^ = 0 . 9 9 8 ) and 7?= 1.0+1.017 • 10" 2 • S2A (rx, = 0.994) respectively. The subjects' heart rates were higher for running than for either of the two walking styles up to 8.2 km h ~ *. At this velocity, the curves for running and competition walking cross each other. The cross-over point between running and ordinary walking can be found at 8.5 km h " 1 (Fig. 3). At 8.8 km h " 1 , the two walking curves cross each other. There is, however, only one common velocity level after the cross-over point between the walking curves. This point is studied further in part 2. The heart rate (HR) increment during competition walking is expressed by HR = 59 + 1.181 • Si/J (^=0.999). The corresponding function obtained for ordinary walking is HR = 57+ 0.607 • S20 (rxy=0.999). The blood lactate curves for ordinary walking and competition walking are mainly parallel, although at slightly different levels, up to the point where the subjects finished ordinary walking (Fig. 4). Above that point (10 km h~ 1 ), the curve for competition walking starts to accelerate. The blood lactate curve for ordinary walking is best described using linear regression (Y= 1.999 • 10~ 3 • x +1.3; rX), = 0.674). In order to describe the increase of competition walking there is a need for a b-value (Borg, 1962, 1973). The function is: R= 1.79 + 9.883 • 10" 3 • (S-9)30 (r, =0.999).
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o
CC
o
109876543210 10" 9876543212.5
5.0
12.5 15.0 17.5 7.5 10.0 1 h " ) Velocity (km Fig. 2. Perceived chest exertion and breathlessness (Chest) as well as leg exertion (Leg) during part 1, measured with Borg's CR-10 scale for running (on the two separate test occasions, Run 1 and Run 2), ordinary walking (OW) and competition walking (CW). 0.0
A comparison between the measurements of VO2 max does not reveal any significant differences between competition walking and running. However, the data for one of the subjects show that while race walking he used less than 90% of his VO2 max observed during running (see Table 1). Part 2
In part 2, the maximal velocities were set to 14kmh - 1 for competition walking and 1 2 k m h - 1 for ordinary walking. The results confirm the findings from part 1, with a cross-over point for heart rate between ordinary walking and competition walking at 8.6 km h" 1 (Fig. 5). Concerning chest and leg exertion, as well as blood lactate, no corresponding cross-over
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2004T 180.E 160 i
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4020
0.0
2.5
5.0
7.5 10.0 12.5 15.0 17.5 Velocity (km h~ 1 ) Fig. 3. Heart rate (beats min"1) during part 1 for running (on the two separate test occasions, Run 1 and Run 2), ordinary walking (OW) and competition walking (CW).
8OWI OW II CWI
7o E E.
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o m
210.0
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7.5 10.0 12.5 15.0 17.5 Velocity (km h " 1 ) Fig. 4. Blood lactate during part 1 for ordinary walking (CW I) and competition walking (CW I) and during part 2 for ordinary walking (OW II). points are found. Nor are there any significant differences between the growth of the curves when comparing competition and ordinary walking. The heart rate functions found in part 2 are very much the same as in part 1. For competition walking, the function is R = 57 +1.4057 • S1"7 ( ^ = 0.998) and for ordinary walking #=57+0.5512 • S 2 1 ( ^ = 0.999). During ordinary walking, there was no increase in blood lactate in part 1. In part 2, where 1 2 k m h " ' was included, the function expressing the accumulation of blood lactate is # = 0.92 + 1.6912 • 10 ~ 5 • S 4 - 8 (rx =0.977) (see Fig. 4).
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1
^ O 2 max
ml k g " min"
1 2 3 4
5.3 3.7 4.5 4.8
74.0 60.3 67.0 66.4
4.7 3.5 4.6 5.0
64.9 56.6 69.2 70.3
X
4.6 0.7
66.9
4.5 0.7
65.3
S.D.
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Competition walking 1
VO2 max
5.6
ml kg * min
1
6.2
180" •
160" c
I
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140"
(3 120100-
** w
CO
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80-
*^
60ACl .
4
5
6
7
8
9
10
1 1 1 2 1 3
14
Velocity (km h" 1 ) Fig. 5. The cross-over point for heart rate determined in part 2 between competition walking (CWII) and ordinary walking (OW II).
Discussion Because they were highly trained athletes, the subjects were able to perform ordinary walking at higher levels than non-athletes are usually able to (Menier and Pugh, 1968). However, in part 2, the subjects had some difficulty performing'ordinary walking'at 12 km h " 1 , and they sometimes oscillated between ordinary walking and competition walking. This might, of course, influence the results to a certain degree when comparing the two walking modes. To what extent and in what direction, however, is difficult to judge. As can be seen from the results, however, the growth functions for ordinary walking obtained in part 1 and part 2 respectively, as well as for competition walking, concerning both heart rate and the psychophysical variables, were very much the same on the two test occasions. The subjects were constantly reminded of the necessity to stick to 'ordinary walking' and for the most part they were able to do so. They also verified that it was quite a different feeling to walk ordinarily, as compared to competition walking, at 12 km h " 1 . This velocity is therefore included in the calculations.
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The two different parts of the test were performed with an interval of almost \\ years. The subjects' weight had not changed significantly between the two test occasions even if two of the subjects were a little less active in their training the second time. There were no significant differences between the subjects' heart rate levels in parts 1 and 2, neither for competition walking nor for ordinary walking. Additionally, the heart rate functions were almost identical. As for the two test sessions within each part, and the rest periods of 30 and 20 min, there were no significant differences between the pre-test values and the values recorded after the rest periods. This indicates that a sufficient physical recovery had taken place, before the second halves of the test sessions. The correspondence of the heart rate curves between parts 1 and 2 indicates that the strain was very much the same in the two parts of the test. As found earlier (e.g. Borg et al., 1987), heart rate for ordinary walking was increasing according to a squared function. Competition walking includes additional biomechanical techniques which allow the subjects to walk at faster speeds. The slightly lower exponent in the heart rate growth function for competition walking may reflect this. The exponent is found to be between those usually found for running and ordinary walking, but a little closer to the latter. It is interesting to note that the chest exertion growth function is almost the same for the two walking modes, although the level of exertion seems to be a little lower for ordinary walking (N.S.). This means that the strain on chest and breathing is about equal for both. Even the two leg exertion curves follow each other closely, but as can be seen on the exponents the ordinary walking curve accelerates a little faster. Bearing in mind the biomechanical limitations for ordinary walking at higher velocities, this faster acceleration is understandable. The straight line obtained for the blood lactate increase during ordinary walking in part 1 means that, for this group of trained athletes, the accumulation of blood lactate starts after 10 km h ~1. The exponent of the lactate growth function for competition walking obtained in part 1 was very much the same as that found for running in the study by Borg et al. (1987). Moreover, the exponent of the blood lactate function for ordinary walking in part 2 was almost identical to what has been found earlier for walking (Borg et al., 1987). The curves for competition and ordinary walking cross each other at 8.6 km h~ * and the ordinary walking curve starts to accelerate more than the competition walking curve. This indicates that at this velocity, competition walking becomes physiologically more economical than ordinary walking, which is the most economical means of motion at lower velocities. The difference between the two walking modes is, however, small. This cross-over point is of the same magnitude as that usually found for running and ordinary walking. This strengthens the assumption that ordinary walking becomes physiologically uneconomical as a mode of locomotion at about this velocity, which is also in accordance with earlier findings of cross-over points mainly between 8 and 9 km h" 1 (Menier and Pugh, 1968; Noble and Borg, 1972; Hagberg and Coyle, 1984; Borg et al, 1987). The results also point to the great similarity between competition walking and running concerning efficiency during motion. The comparison between the values of maximal oxygen uptake revealed no significant difference between running and competition walking. The results also indicate a close similarity in the economy of locomotion of competition walking and running. This is in accordance with the findings of Hagberg and Coyle (1984) who found that VO2 max was the same during competition walking as during running among eight competition walkers. In conclusion, this study shows that the variables measured can be described by monotonically accelerating power functions for competition and ordinary walking. For
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competition walking, the chest and leg exertion functions have the exponents 2.1 and 1.9 respectively. The heart rate growth function accelerates with the exponent 1.7, and blood lactate with 3.0. With this last function, there is also a need for a b-value, meaning that the curve does not start to accelerate immediately. Furthermore, the study shows that competition walking becomes a more economical way of locomotion than ordinary walking at velocities above 8.6 km h~ 1 . This finding resembles what is usually found for running and ordinary walking, which in various studies shows a cross-over point between 8 and 9 km h" 1 . Finally, the study shows that elite competition walkers are able to reach VO2 max values during competition walking as high as those during running. Acknowledgements This research was supported by grants 14/86 and 22/88 from the Swedish Sports Research Council. References Borg, G. (1962). Physical performance and perceived exertion. Studia Psychologica et Paedagogica, Series Altera, Investigationes XI, Lund. Borg, G. (1973). Perceived exertion during walking: A psychophysical function with two additional constants. Reports of the Institute of Applied Psychology, University of Stockholm, 39, 1-10. Borg, G. (1982). A category scale with ratio properties for intermodal and interindividual comparisons. In Psychophysical Judgment and the Process of Perception (edited by H. G. Geissler and P. Petzold), pp. 25-33. Berlin: VEB Deutscher Verlag der Wissenschaft. Borg, G. and Dahlstrom, H. (1959). Psykofysisk undersokning av arbete pa cykel-ergometer. Nordisk Medicin, 62, 1383-6. Borg, G. and Dahlstrom, H. (1960). The perception of muscular w o r k - a psychophysical study of short-time work on the bicycle ergometer. Publications of the Research Library, No. 5, Umea. Borg, G., van den Burg, M., Hassmen, P., Kaijser, L. and Tanaka, S. (1987). Relationships between perceived exertion, HR and HLa in cycling, running and walking. Scandinavian Journal of Sports Sciences, 9, 69-77. Forsberg, A. and Lundin, A. (1975). Idrottsfysiologi, G&ng. Trygg- Hansa, Report No. 15. Hagberg, J.M. and Coyle, E.F. (1984). Physiologic comparison of competitive racewalking and running. International Journal of Sports Medicine, 5, 74-7. Karlsson, J., Jacobs, I., Sjodin, B., Tesch, P., Kaiser, P., Sahl, O. and Karlberg, B. (1983). Semiautomatic blood lactate assay: Experiences from an exercise laboratory. International Journal of Sports Medicine, 4, 52-5. Menier, D.R. and Pugh, L.G.C.E. (1968). The relation of oxygen intake and velocity of walking and running, in competition walkers. Journal of Physiology, 197, 717-21. Mihevic, P.M. (1981). Sensory cues for perceived exertion: A review. Medicine and Science in Sports and Exercise, 13, 150-63. Noble, B. and Borg, G. (1972). Perceived exertion during walking and running. In Proceedings of the XVIIth International Congress of Applied Psychology, Vol. 1, pp. 387-92. Brussels: Editest. Pandolf, K.B. (1983). Advances in the study and application of perceived exertion. In Exercise and Sport Sciences Reviews (edited by R.L. Terjung), Vol. 11, pp. 119-58. Philadelphia: Franklin Institute Press. Payne, A.H. (1978). A comparison of the ground reaction forces in race walking with those in normal walking and running. In Biomechanics VI-A (edited by E. Asmussen and K. Jergensen), pp. 293-302. Baltimore, Md.: University Park Press.
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Rippe, J.M., Ward, A., Haskell, W.L, Freedson, P., Franklin, B.A. and Campbell, K.R. (1986). Walking for fitness. The Physician and Sportsmedicine, 14, 145-59. Rydevik, U., Nord, L. and Ingman, F. (1982). Automatic lactate determination by flow injection analysis. International Journal of Sports Medicine, 3, 47-9. Wyndham, C.H. and Strydom, N.B. (1971). Mechanical efficiency of a champion walker. South African Medical Journal, 45, 551-3.
