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Ergonomics Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/terg20
Preliminary observations on parameters of human location a
R.N. DAS & S. GANGULI
b
a
Mechanical Engineering Department , Bhagalpur College of Engineering , P.O. Sabour, Bhagalpur, 813210, India b
Bio-Engineering unit, Department of Orthopaedics and Artificial Limb and Appliances Centre , University College of Medicine, University of Calcutta , Calcutta, India Published online: 24 Oct 2007.
To cite this article: R.N. DAS & S. GANGULI (1979) Preliminary observations on parameters of human location, Ergonomics, 22:11, 1231-1242 To link to this article: http://dx.doi.org/10.1080/00140137908924697
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ERGONOMICS,
1979,
VOL.
22,
NO.
II, 1231-1242
Preliminary observations on parameters of human location BY R. N. DAs Mechanical Engineering Department, Bhagalpur College of Engineering, P.O, Sabour, Bhagalpur 813210, India
and S. GANGULI
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Bio-Engineering unit, Department of Orthopaedics and Artificial Limb and Appliances Centre, University College of Medicine, University of Calcutta, Calcutta, India A preliminary experimental field investigation was conducted on seventeen normal male adults to study the important observable parameters of human locomotion and the interrelationship existing among them. New generalized terms such as specific speed (statures s - 1), specific energy consumption (kJ kg- 1 min - I), percentage increase of peak heart rate and a non-dimensionalized term, relative step length, have been introduced. Superiority of cadence and specific speed over speed and specific energy consumption over energyconsumption has been observed and a single linear relationship connecting specific speed and specific energy consumption up to a speed of 6·7 m S-l (24 km h- l ) has been seen. Stair climbing and Baithaki exercises have been included as two other rhythmic activities for the sake of comparison with locomotion. Use of cadence as a relatively more important observable gait parameter for walking or running activity as well as for other rhythmic activities has been suggested. These findings have potential for application in the field of work study and industrial engineering..
I. Introduction In the field of work study as a measure of performance evaluation the' rating' (that is, rate of working) of industrial workers is based on the equivalent speed of level walking (Introduction to Work Study 1974). The standard rating in the USA and UK corresponds to the speed of motion of limbs of an average man walking straight without any load on level ground at a rate of 1'8 m s - 1 (6-4 km h - 1). This is the average speed of walking which a normal healthy worker is expected to maintain with optimum energy consumption. While this may hold good in countries like the USA and UK, it must be appreciated that the average speed of walking, as with any other physical activity, depends on geographical, climatic, sociological, ethnic, and nutritional conditions and may vary from country to country. In India, the average speed of level walking for industrial workers has been reported by Ganguli (1973, 1977) to be 1·25 m s -1 (4'5 km h - I) and not 1·8 m s " 1 (6-4 km h - t) which is universally followed in industrial engineering practice. The energy cost of walking on level ground at varying speeds has been measured by biomechanical engineers and physiologists from time to time. Interestingly, Durnin and Passmore (1967) have shown a linear relationship between energy expenditure and speed over the narrow range of 0,97-1·8 m S-1 (3,5-6, 5 km h -I), whereas Bard and Ralston (1959) observed tha t at speeds significantly above or below 1·14 m s - I (4'1 km h - '), the energy cost per metre walked increased rapidly. This paper reports an investigation that was undertaken with the object of determining the relationship between speed and energy expenditure and also to compare some of the observable gait parameters in relation to their suitability and rationality of use in different activities. Activities selected were walking, running, stair climbing and Baithaki exercise. Baithaki exercise is a common physical exercise prevalent in Indian villages. It comprises OO\4-0IJ9/79/2211 1231502.001:9 1979 Taylor & Francis Ltd
R. N. Das and S. Ganquli
1232
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lowering of the body from the standing position by bending the knees only till the buttocks approach the heels and subsequently raising the body to the upright position again by stretching the knees. 2. Method This report is based on preliminary experimental studies conducted on seventeen normal young male adults. All were undergraduate students of average age 25·17 ± 4·27 yrs, average weight 59·56 ± 5·71 kg, and average height 1·68 ± 0·065 m of the Bhagalpur College of Engineering, Bihar, India, comprising twelve from India and five from Nepal, who volunteered to become subjects for this study. The purpose of the present work was to study the interrelationship among various gait parameters; namely, cadence, speed, step-length, and cycle-time vis-a-vis the subjects' heart rates in the pre- and post-activity periods and their rates of energy consumption. After having explained the purpose and method ofconduct of this study to generate the necessary motivation to the subjects, all the data according to the Human Locomotion Chart (Appendix B) were recorded. The walking and running activities were conducted in the open air on the level playground of the college in the months of March and April during the morning hours (0800--1 100 h). The mean dry bulb temperature recorded was 25°C (23°-27°C) and relative humidity varied between 63 and 69 %. Pre-activity and post-activity heart rates were measured in the supine and sitting postures respectively during the post-absorptive periods. On the basis of a preliminary study conducted earlier on a few subjects, the range of speed during running activity was arranged in 5 progressive steps from walking to maximum running speeds. This was explained to the subjects and they were asked to maintain uniformity of stepping as well as speed throughout the full stretch of any walking or running event. 2.1. Watkin!! and running actioit v A straight line measuring I 10m between points C and D with a central zone, AB, measuring 100 m was marked by chalk on level ground (Figure I). All the subjects were to walk or run as necessary, traversing the straight stretch AB measuring 100 m starting at C and stopping at D. Time was measured with stop watches (O'l s accuracy, Rocar) by two time-keepers positioned at E and F who pressed the knob of the stopwatches as soon as the torso of the subjects crossed point A or B. Each time-keeper simultaneously pressed the knob of his stop-watch and raised one arm to signal the information that the subject had crossed point A or B. Thus each time-keeper measured the time taken by the subject either to walk or to run the distance AB. The mean of these two times was recorded to calculate the mean ground speed of the subject in that event. Similarly, the number of steps was counted by another group of two individuals conveniently positioned in order to see the movement of the subjects' legs and the time-keeper's signalling. The mean of these step countings was recorded Sm
c
1••- - - - l 0 0 m ----~I Sm A
E Figure 1.
B
_
o
F
A line diagram showing the walking and running track.
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Preliminary observations on parameters of human locomotion
1233
for calculation of cadence, cycle-time etc. The gap between any two activities was kept sufficient so that, at the beginning of each walk or run, the pre-activity heart rate was approximately the same as the initial pre-activity heart rate of that day. The pre-activity heart rate (resting heart rate) was measured by counting five times the number of pulse beats in sixty seconds in the supine posture preceding the first walk or run and taking the mean of the five counts. In subsequent runs the preactivity heart rate was measured once or twice to see if there was any variation from the initial value. In the case of any variation, more resting time was given to stabilize to the normal heart rate. The pulse beat was palpated in all cases at the subjects' wrist. The post-activity heart rate (peak heart rate) was measured by counting the time for twenty pulse beats immediately after each walking or running activity in the sitting posture on a chair. In this case, two recorders took the time for twenty pulse beatsone for the left hand and the other for the right and the mean of these two values was recorded. Factors, which affect the heart rate, such as smoking, ingestion of food, emotion and the thermal environment were explained to the subjects before the study was undertaken and the necessary precautions were taken accordingly for the first three factors. As regards the effect of temperature, all the subjects were exposed to the same environmental changes (slight rise of temperature only) and as such would have been similarly affected. 2.2. Stair climbinq A smaller group of subjects climbed up a staircase without any load. The staircase in Hostel No.2 of the Bhagalpur College of Engineering, where the subjects normally reside, was chosen so that no psychological factor would presumably affect the postactivity heart rates. The test was conducted in the morning hours in the post-absorptive periods. The staircase leading to the first floor from the ground floor has one halflanding in the middle. All subjects were asked to follow the same pattern of climbing up the steps and to negotiate the turning in the half-landing in the same fashion by not taking too large a path radius. The rise and tread of the steps were measured in the same way as in the walking or running activities. 2.3. Baithaki exercise The same group which took part in the stair climbing participated in the Baithak i exercise. The experiments took place during the morning hours in the post-absorptive periods. This exercise was conducted at three speeds of increasing Baithuk i cadence (number of Baithakis per minute). The time for twenty Baithakis was noted by timekeepers and the mean value recorded. Pre- and post-activity heart rates were measured us before. Energy consumption has been reported to bear a straight line relationship with heart rate ratio as described by Ganguli, Bose, and Datta (1976). The same relationship has been used here for the determination of' energy cost' in all the four activities. The relationship is given by E = 4'187(6 HRR - 5'1),
where
E= energy consumption (kJ min -I). and HRR
Heart rate ratio Peak heart rate (Post-activity heart rate) Resting heart rate (Pre-activity heart rate)
1234
R. N. Das and S. Ganquli
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It may be pointed out here that the above relationship was obtained in the estimation of energy cost in walking without any load and with graded loads only at a speed of 0·83 m S-I (3 km h-'). In the present study the same formula has been applied to calculate the energy cost of subjects walking or running without any load but at a much higher rate (maximum speed 6·7 m S-I (24,2 km h- I)) and performing other activities (stair climbing and Baithaki exercise).
3. Results and discussions 3.1. Walkint; and runninq actiuit v Table I provides detailed information regarding the height, weight and resting heart rate of the subjects. Table 2 presents the results obtained in respect of the speed, cadence, step length, heart rate ratio (HRR), percentage increase in postactivity heart rate ratio over pre-activity heart rate (%PHR) and energy consumption characteristics for the activities of walking and running. Tables 3 and 4 contain similar data for the activities of stair climbing and Baithak i exercise respectively. Plots of dependent variables like heart rate ratio (HRR), percentage increase in post-activity heart rate over pre-activity heart rate (%PRR), energy consumption E (kJ min-I), specific energy consumption E* (kJ kg-' min-I), and step length L (m) have been shown in the ordinate (Y -axis) against the three parameters, speed, V (km h - I), specific speed, V* (statures s - I), and cadence (C) in the abscissa (X-axts) for the sake of comparative study in Figures 2 to 7. Figure 2 shows that speed V and cadence C had a non-linear relationship throughout the whole range of walking to running 1-4-6'7 m S-I (5:...24 km h- 1 ) whereas specific speed (stature s -') had a linear relationship with cadence, which suggests that both specific speed and cadence may serve equally well as independent observable gait parameters contrary to speed. Figures 2 and 3 show that, within the absolute speed range 1·4-6·7 m S-I (5-24 km h- I), the energy consumption and speed V Table I.
Physical details of the subjects.
Age (years)
Sex
Height (m)
Barefooted weight (kg)
3." P. N. Singh 4. B. K. Choudhary 5. R. C. Ravidas 6. S. G. Ahsan 7. S. K. Sinha 8. S. S. Prasad 9. B. Thakur 10. S. S. P. Singh II. V. L. Shrestha 12: S. K. Gurung 13. H. Shrestha 14. S. R. Rizal 15. 1". H. S. Singh 16. M. A. Samad
25 26 26 25 29 24'5 24·5 31 24 25 23 24 21 23 J9 20
M M M M M M M M M M M M M M M M
1·725 1'63 1·66 \·712 1·59 1'62 1·73 1'67 1'80 1·73 ),70 J.7) 5 ),64 1·605 \·67 1'76
60 53'5 68 57 52'5 65 66 78·5 60'5 59·5 59 65·5 50·5 52 54·5 54·5
17. T. C. Prasad
38
M
1'63
56
1·68 (± 0'056)
59-56 (± 5'714)
SI. No.
Name of subject
I. A. Pandey 2. N. Puswun
Place of
Resting heart rate (beats
normal residence
min-I)
Indian plains Indian plains
64-86 63'15 70·00 66'66 70·96 64'17 74·07 67·00 70·00 63'15 74'53 74·07 74'53 61·85 61·22 64'17
Indian plains Indian plains Indian plains Indian plains Indian plains
Indian plains Indian plains lndian plains Nepal Tarai Nepal Tarai Nepal Tarai Nepal Tarai Nepal Tarai
Tripura (Indian hilly terrain)
Arithmetic mean: Standard deviation:
25'17 (± 4'27)
Indian plains
56'00
5.
4.
3.
2.
I.
10418 ( ±0·184) 1·98 (±0·127) 4·15 ( ±0·267) 5·765 (±0·51) 6·72 (±Oo43)
5·128 ( ±0·673) 7·13 ( ±Oo455) 1495 I ±0·949) 20·76 (± 1·84) 24·2 (± 1·54)
S-l
m
km h- I
VI
Mean speed
0·854 ( ±0·087) 1·24 ( ±0·065) 2-485 (±0·14) 3-26 ( ±0·27) 4·06 ( ±0·268)
statures 5- 1
V'
N.B. Figures under bracket denote standard deviation.
S. No.
V 119-42 (±5·31) 136·3 (±7-81) 175-6 (±6·14) 200·6 ( ±9·348) 231·7 (± 16·5)
C
Cadence
Mean
Table 2.
1·548 (±0·212) 1·698 (±0·20) 2·01 ( ±0·203) 2·158 ( ±0·2ISl 2-48 ( ±0·26Il
HRR
Mean 16·748 (±4-31)
54·07 (± 19·8) 72-84 (± 19-49) 102·10 (±21·05) In·50 I± 1986) i 52·0 (±25·0) t ±4·81) 30·73 ( ±4·31) 35-54 (±5·6) 38·52 ( ±8·79)
noo
kJ min-I
E
0·322 ( ±0·142) 0·397 ( ±0·104) 0·565 ( ±O·129) 0·657 (±0·146) 0·782 (±0·167)
kJ kg- 1 min-I
E'
Energy consumption
%PHR
Mean
Walking and running activities.
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O·g~O
( ±0·0271 10434 (±O·O72) 1·6X3 ( ±0·082) 1·73 ( ±0·067)
L*
( ±0·058) 1·04 ( ±0·022)
0·~g2
0442 ( ±0037l 0530 ( ±0·0269) o·g) 1 (±O·O481
Step length
0·761 ( ±0·059)
L m
'""
W
N
is· =:
(5
g
s-
§
=:
§"
~
Co
'"
iii ..,
..,
s'"
":::
g
Co
=:
:2.
'5·"
~
~
"
.~
'"
~.
::p §" ~
R. N. Das and S. Ganquli
1236
Table 3.
mean HRR
(kJ min-I)
PHR
0'861 ( ±0'068)
1·76 (±0'166)
22-86 ( ±3'97)
76·0 (± 17'52)
Energy consumption
Table 4. SI. No. Mean Baithaki Cadence
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3.
of
Baithaki Exercise. Energy consumption
%increase
Mean HRR
(kJ min-I)
ofPHR
1·706 ( ±0'088) 1'835 (±0'107) 1'92 ( ±0'204)
21'56 (±1·84) 24'74 ( ±2-67) 27'00 (±5'191)
71
26'43 ( ±5-68) 39·22 (±6'98) 52-96 ( ±3-82)
2.
% increase
Mean Ascending Velocity km h- I 0·239 (±0'019)
I.
Stair Climbing.
83 92
Figures under bracket denote standard deviation.
1'2
*
1'0
*~
L
o-e
..-"
...-.l:J,_._-~
....-.~.~·-"·L x.. _~_ . . -x------_x
0'6
t
0'4
*>
s-:......... a 3
_---1-0...J
x.......... x ...
0'5
2
>
'0
110
190
210
230
C ----
Figure 2.
Variation of speed, specific speed, step length and relative step length with cadence.
HRR \.
..tJ.-------s->:"
OfoPHR ,,
o-" " -0-- - ; .
"0
E\.
_ -o-
-----If"- _----~ _-0
-0--"
cc
it
100 40
30t 20'"
t
110
Figure 3.
t
ISO
_-'"t1""---
Variation of HRR, %PHR, Eand E- with cadence.
"
Preliminary observations on parameters of human locomotion
1237
t
*~
25 20
t
15 > 10
2
3
4
SPECIFIC SPEED
Figure 4.
v*_
5
Variation of speed, step length and relative step length with specific speed of walking and
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running.
0'8
0'7
125t 1000::: I n,
75", 0·3 SO
o
2'0
1·0
3'0
4'0
SPECIFIC SPEED
Figure 5.
5'0
V* ~
Variation of HRR, %PHR, E and E· with specific speed of walki'f and running.
~2'0"r
t '" c,
I
'"
1'5 0'50
HRR \
x
A: sr"
" " ~ _,c,-,-.%PHR X," '" x ; , ' -»
.F' r:f
L"" -",/'
E .......
40 2'0 1'5
"0 0'5
t
35 30
~
25
t w
20 15
Figure 6.
Variation of HRR, %PHR, step length and E with speed of walking and running.
R. N. Dos and S. Ganquli
1238
ID
IS
20
25
SPEED V ~
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Figure 7.
Variation of relative step length. L· and E* with speed of walking and funning.
(km h -I) relationship was non-linear, though with cadence the energy consumption relation was linear at first but became non-linear at higher cadence values. Contrary to this, specific energy consumption increased linearly with cadence as well as with specific speed (Figure 5). However, both these observations presumably would restrict themselves to a group of persons having little or no variation in stature and body weight as was the case in the present investigation. To establish the general validity of these findings, it would be necessary to apply the same tests to different groups of subjects having different heights and weights. Figures 2 to 7jointly convey that although absolute speed V increased with cadence in the beginning with slow running and consequently energy consumption E (kJ min - I) also increased linearly with cadence, with a further increase of cadence, speed V and energy consumption E appeared to rise rather slowly, nevertheless, the specific speed V* (statures s" I) and specific energy consumption E* (kJ kg- 1 min - I) continued to rise linearly with cadence. Two reasons can perhaps be attributed to explain the above fact: (a) Figures 2 and 4 show that step length L did not increase linearly with cadence (or specific speed) at higher running speeds; thus speed which is a function ofthesrroduct of cadence and step length, cannot increase at such a rate as it did at slow running speeds; and (b) the specific energy consumption continued to increase with cadence or specific speed as the body movement is faster at an increased cadence and thus energy must be expended in the increased activity condition. This suggests that, cadence or specific speed in the case of the group studied appeared to be more representative as a gait parameter than speed of locomotion. Figures 3 and 5 respectively show a linear relationship between heart rate ratio HRR and cadence C and HRR with specific speed V*. Similar relationships exist between %PHR and cadence or specific speed (Figure 4). This suggests that %PH R can also be used as an index of energy cost as well as HRR. The plot of %PHR and HRR on a speed base has been seen to be non-linear (Figure 6) and this indicates once again the inefficiency of speed as a gait parameter compared to cadence or specific speed in the group of subjects of the present investigation. The specific energy consumption,E* (kJ kg-I min-I) has a linear relationship with specific speed V* (statures s-') up to 4 statures S-I (equivalent speed 6·7 m s-' (24'2 km h- I )) , where~s the energy consumption, E (kJ min-I) and speed, V (km h- I ) relationship is linear up to 1·8 m S-I (6'5 km h-') only. Thus a single linear relation between specific energy consumption and specific speed (from walking to running) can be obtained for the whole range of human locomotion on the level.
Preliniinarv obseroations on parameters of human locomotion
1239
However, as pointed out already, this hypothesis needs to be validated by extending the investigation on more subjects of different heights and weights.
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3.2. Stair climbinq Table 3 shows the mean value of ascending speed 0·066 ± 0·005 m S-1 (0,239 ± 0·019 km h - 1) with a corresponding mean value of HRR (I. 76 ± 0'166) and energy consumption (22'87 ± 3'97) (kJ min - '). This exercise could not be carried out at different speeds because of many practical difficulties, such as danger ofslipping while climbing at higher speeds and exhaution of the subjects after a few steps had been climbed at higher rates of climbing. However, the small magnitude of the standard deviation of the mean values, based on a sample of 5 subjects did show consistency of results. 3.3. Baitliak! exercise Figure 8 shows the mean values of %PH R, HRR, and energy consumption E as a function of the Baithaki cadence. As expected, the relationship is linear in all the three cases confirming that cadence is the governing parameter, not only in gait-study but possibly in other human activities also where a rhythmic type of work is involved. On inspection of the Human Locomotion Chart in the Appendix it is apparent that, out of various parameters relevant to locomotion, only a few have been covered so far. Interrelationship among other parameters, like step length L, subjects' height H, cycle time T. or cadence C seem to be straightforward. The simple fact of experience suggests that tall people normally take longer steps at a slower cadence and short persons take shorter steps at an increased cadence. Hence, the value of the ratio THI2L was calculated for walking activity only. It was observed that values of the quantity K = THI2L became almost constant for 17 subjects (K = 1·07 ± 0,06). Similarly the value of the Ponderal Index
PI
=
H
ijW'
where H
= Height of the subject (m)
W
=
Weight of the subject (kg)
for the first 10 subjects gave a mean value of 0·4319 ± 0·09.
28
22
20
30
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1240
R. N. Das and S. Ganquli
4. Conclusion This investigation has shown, although in a limited way, that cadence and specific speed would emerge as relatively more useful gait parameters with which most of the other dependent observable parameters can suitably be related. Cadence is easy to measure with a stopwatch and even without the knowledge of the subject being observed, and has an added advantage over other parameters such as speed where accurate measurement of distance and time is required. This is particularly relevant in the context of work measurement where rating the performance of an individual worker engaged iii a rhythmic activity, in terms of speed of walking (as is done today throughout the world) poses perceptual problems and thus becomes an unrealistic and futile exercise. Visualizing a physical work rhythm in terms of cadence is much more objective. This study has also highlighted that as a standard basis of energy cost, the unit should always be in kJ kg-' min - I for better rationality. This investigation has indicated that speed would also be expressed in terms of statures s-, (instead of conventional unit km h - 1 or m s - '). However the suggested unit of speed in statures s -, may not be appreciated quantitatively at the beginning by many, as it does not give a correct idea of how fast or slow the subject is moving. Therefore it is proposed that with the conventional unit of speed in m s - I. or km h - I, the non-conventional speed in statures S-I should be mentioned in parenthesis. It could perhaps be used on a trial basis for comparison of different speeds of activity in rating workers in Industry and Agriculture. The importance of cadence as a governing parameter has been confirmed in another activity like the Baithaki exercise and hence can also be generalized for other repetitive work. A distinct limitation of this preliminary investigation has, nevertheless, been the larger standard deviations of some of the parameters (Tables 2, 3, and 4). This could be avoided by taking larger samples and improved experimental procedures, which the authors propose to incorporate in their future work.
V'"
V
,
H
Specific speed (statures
S-I).
Weight (bare-footed) of a subject (kg). Height or stature (bare-footed) of a subject (m). Step length, stride length (m).
W H L
L*
Glossary Walking Running speed on level ground (km h - '). Walking/Running speed on level ground (m S-I).
L H
T
C RHR PHR %PHR PHR HRR = - RHR E
Relative step length. Time period for one cycle (s). Cycle time. Cadence (Number of steps per minute). Pre-activity Heart Rate (Resting Heart Rate) (beats min -') Post-activity Heart Rate (Peak Heart Rate) (beats min - [). Percentage increase in PHR over RHR after any activity. Heart Rate Ratio. Energy consumption (kJ min - ').
Preliminarv observations E* =
E
W H K= 2L
Be
parameters of human locomotion
1241
Specific energy consumption (kJ kg-I min -I). A constant (characteristic of level walking). Baithaki Cadence (No. of Baithakis min - I).
H
P1=
011
Vw
Ponderal Index.
Une recherche pre-liminaire sur Ie terrain a etc effectuee sur J 7 sujets adultes masculins afin de determiner
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les parametres importants concernant la marche, ainsi que les relations qui existent entre eux. Des termes nouveaux leis que "vitesse specifique", "consommation specifique d'energie" (kJ .kg- ' min -I) "pourcentage d'augmentation de la frequence cardiaque de pointe" et une grandeur sand dimension: "la longueur relative d'un pas" ont etC utilises. On a observe une superiorite de 1a cadence et de 1a vitesse specifique sur la vitesse, ainsi que de la consommation specifique denergie sur l'energie. De rneme une relation lineaire est apparue entre la vitesse specifique et la consommation specifique pour des vitesses allant jusqu'a 6,7 m.s- 1 (24 km.heure). Dans les comparaisons on a inclu l'ascension d'un escalier et des exercices de Baithaki qui constituent des taches rythmiques au meme titre que la marche. On suggere d'utiliser 1a cadence en tant que parametre observable Ie plus important pour la marche et la course ainsi que pour d'autres activites ryrhmecs. Les resultats peuvent ctre utilises pour l'etude du travail.
Eine experimentelle Voruntersuchung im Feld wurde mit 17 normalen erwachsenen Mannern durchgefUhrt, urn die wichtigsten wahrnehmbaren Parameter der menschlichen Fortbewegung und die Beziehungen, die zwischen ihnen bestehen, zu untersuchen. Neue allgemeine Ausdrucke, wie z.8. die spezifische Geschwindigkeit (S-I), der spezifische Energieumsatz (KJKg- 1 min -1), der prozentuale Anstieg der Herzschlagfrequenz, und ein dirnensionsloser Ausdruck, ntimlich die relative Schriulange wurden eingefUhrt. Eine Uberlegenheit der rhythmischen und spezifischen Geschwindigkeit i.iber der Geschwindigheit und eine Oberlegenheit des spezifischen Energieumsatzes i.iber dem Energieumsatz wurde beobchtet und es wurde eine einzige lineare Abhangigkeit zwischen der spezifischen Geschwindigkeit und dem spezifischen Energieumsatz bis zu einer Geschwindigkeit von 6.7 m s" I) (24 krn h ~ 1) festgestellt. Stufensteigen und Baithaki Ubungen wurden a1s zwei weitere rhythmische Tatigkeiten wegen des Vergleichs mit der Fortbewegung mit eingeschlossen. Die Verwendung des Rhythmus als ein verhaltnismabig wichtigerer wahrnehmbarer Gangparameter wurde filr Geh- oder Laufbewegungen ebensogut wie fur andere rhythrnische Tatigkeiten vorgeschlagen. Diese Untersuchungen haben fur die Anwendung im Bereich yon Arbeitsstudium und Industrial Engineering Moglichkeiten.
References BARD. G.. and RALSTON. H. J., 1959. Measurement of energy expenditure during ambulation with special reference to evaluation of assistive devices. Archives of Physico! Medicine and Rehubilitutinn, 40, 415-420. DURNIN, J. V. G. A., and PASSMORE. R., 1967, Energy Work and Leisure (London: HEINEMAN EDUCATIONAL BooKS).
GANGULI, S., t 973, Observations on the basic gait characteristics of Indian Industrial Workers. Indian Journal of Industrial Medicine. 19,28-35. GANGULJ, S., BOSE, K. S., and DATTA, S. R.. 1976, A new method of energy evaluation in Rehabilitation clinics. I.S.P.O. Bulletin. 20, 4-5. GANGULI, S., 1977, Human Engineeringfor Belfer Munaqement, (Calcutta: KWALITY BOOK COMPANY).
GRIEVE. D. W.• and GEAR. H. J., 1966. The relationship between length of stride, step frequency. lime of swing and speed of walking for children and adults. Ergonomics, 9, 379-399. Introduction to Work Study, 1974. (Geneva: INTERNATIONAL LABOUR OFFICE). Fourth Impression. Manuscript received 28 August 1978. Revised manuscript received 9 May 1979. ERG.
51
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R. N. Das and S. Ganguli
APPENDIX I. 2. 3. 4. 5. 6. 7.
Name and occupation. Date. Time. Dry bulb temperature. Wet bulb temperature. Relative humidity. Age and sex.
H. Height (bare footed) (m). 9. Weight (bare footed) (kg) . . 10. Leg length: (a) hip joint to knee. (b) knee to the ground, and knee to ankle, (c) hip joint to the ground. II. Pre-activity resting heart rate (beats min -'). 12. Post-activity peak heart rate (beats min-')-
Ergonomics Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/terg20
Preliminary observations on parameters of human location a
R.N. DAS & S. GANGULI
b
a
Mechanical Engineering Department , Bhagalpur College of Engineering , P.O. Sabour, Bhagalpur, 813210, India b
Bio-Engineering unit, Department of Orthopaedics and Artificial Limb and Appliances Centre , University College of Medicine, University of Calcutta , Calcutta, India Published online: 24 Oct 2007.
To cite this article: R.N. DAS & S. GANGULI (1979) Preliminary observations on parameters of human location, Ergonomics, 22:11, 1231-1242 To link to this article: http://dx.doi.org/10.1080/00140137908924697
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ERGONOMICS,
1979,
VOL.
22,
NO.
II, 1231-1242
Preliminary observations on parameters of human location BY R. N. DAs Mechanical Engineering Department, Bhagalpur College of Engineering, P.O, Sabour, Bhagalpur 813210, India
and S. GANGULI
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Bio-Engineering unit, Department of Orthopaedics and Artificial Limb and Appliances Centre, University College of Medicine, University of Calcutta, Calcutta, India A preliminary experimental field investigation was conducted on seventeen normal male adults to study the important observable parameters of human locomotion and the interrelationship existing among them. New generalized terms such as specific speed (statures s - 1), specific energy consumption (kJ kg- 1 min - I), percentage increase of peak heart rate and a non-dimensionalized term, relative step length, have been introduced. Superiority of cadence and specific speed over speed and specific energy consumption over energyconsumption has been observed and a single linear relationship connecting specific speed and specific energy consumption up to a speed of 6·7 m S-l (24 km h- l ) has been seen. Stair climbing and Baithaki exercises have been included as two other rhythmic activities for the sake of comparison with locomotion. Use of cadence as a relatively more important observable gait parameter for walking or running activity as well as for other rhythmic activities has been suggested. These findings have potential for application in the field of work study and industrial engineering..
I. Introduction In the field of work study as a measure of performance evaluation the' rating' (that is, rate of working) of industrial workers is based on the equivalent speed of level walking (Introduction to Work Study 1974). The standard rating in the USA and UK corresponds to the speed of motion of limbs of an average man walking straight without any load on level ground at a rate of 1'8 m s - 1 (6-4 km h - 1). This is the average speed of walking which a normal healthy worker is expected to maintain with optimum energy consumption. While this may hold good in countries like the USA and UK, it must be appreciated that the average speed of walking, as with any other physical activity, depends on geographical, climatic, sociological, ethnic, and nutritional conditions and may vary from country to country. In India, the average speed of level walking for industrial workers has been reported by Ganguli (1973, 1977) to be 1·25 m s -1 (4'5 km h - I) and not 1·8 m s " 1 (6-4 km h - t) which is universally followed in industrial engineering practice. The energy cost of walking on level ground at varying speeds has been measured by biomechanical engineers and physiologists from time to time. Interestingly, Durnin and Passmore (1967) have shown a linear relationship between energy expenditure and speed over the narrow range of 0,97-1·8 m S-1 (3,5-6, 5 km h -I), whereas Bard and Ralston (1959) observed tha t at speeds significantly above or below 1·14 m s - I (4'1 km h - '), the energy cost per metre walked increased rapidly. This paper reports an investigation that was undertaken with the object of determining the relationship between speed and energy expenditure and also to compare some of the observable gait parameters in relation to their suitability and rationality of use in different activities. Activities selected were walking, running, stair climbing and Baithaki exercise. Baithaki exercise is a common physical exercise prevalent in Indian villages. It comprises OO\4-0IJ9/79/2211 1231502.001:9 1979 Taylor & Francis Ltd
R. N. Das and S. Ganquli
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lowering of the body from the standing position by bending the knees only till the buttocks approach the heels and subsequently raising the body to the upright position again by stretching the knees. 2. Method This report is based on preliminary experimental studies conducted on seventeen normal young male adults. All were undergraduate students of average age 25·17 ± 4·27 yrs, average weight 59·56 ± 5·71 kg, and average height 1·68 ± 0·065 m of the Bhagalpur College of Engineering, Bihar, India, comprising twelve from India and five from Nepal, who volunteered to become subjects for this study. The purpose of the present work was to study the interrelationship among various gait parameters; namely, cadence, speed, step-length, and cycle-time vis-a-vis the subjects' heart rates in the pre- and post-activity periods and their rates of energy consumption. After having explained the purpose and method ofconduct of this study to generate the necessary motivation to the subjects, all the data according to the Human Locomotion Chart (Appendix B) were recorded. The walking and running activities were conducted in the open air on the level playground of the college in the months of March and April during the morning hours (0800--1 100 h). The mean dry bulb temperature recorded was 25°C (23°-27°C) and relative humidity varied between 63 and 69 %. Pre-activity and post-activity heart rates were measured in the supine and sitting postures respectively during the post-absorptive periods. On the basis of a preliminary study conducted earlier on a few subjects, the range of speed during running activity was arranged in 5 progressive steps from walking to maximum running speeds. This was explained to the subjects and they were asked to maintain uniformity of stepping as well as speed throughout the full stretch of any walking or running event. 2.1. Watkin!! and running actioit v A straight line measuring I 10m between points C and D with a central zone, AB, measuring 100 m was marked by chalk on level ground (Figure I). All the subjects were to walk or run as necessary, traversing the straight stretch AB measuring 100 m starting at C and stopping at D. Time was measured with stop watches (O'l s accuracy, Rocar) by two time-keepers positioned at E and F who pressed the knob of the stopwatches as soon as the torso of the subjects crossed point A or B. Each time-keeper simultaneously pressed the knob of his stop-watch and raised one arm to signal the information that the subject had crossed point A or B. Thus each time-keeper measured the time taken by the subject either to walk or to run the distance AB. The mean of these two times was recorded to calculate the mean ground speed of the subject in that event. Similarly, the number of steps was counted by another group of two individuals conveniently positioned in order to see the movement of the subjects' legs and the time-keeper's signalling. The mean of these step countings was recorded Sm
c
1••- - - - l 0 0 m ----~I Sm A
E Figure 1.
B
_
o
F
A line diagram showing the walking and running track.
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Preliminary observations on parameters of human locomotion
1233
for calculation of cadence, cycle-time etc. The gap between any two activities was kept sufficient so that, at the beginning of each walk or run, the pre-activity heart rate was approximately the same as the initial pre-activity heart rate of that day. The pre-activity heart rate (resting heart rate) was measured by counting five times the number of pulse beats in sixty seconds in the supine posture preceding the first walk or run and taking the mean of the five counts. In subsequent runs the preactivity heart rate was measured once or twice to see if there was any variation from the initial value. In the case of any variation, more resting time was given to stabilize to the normal heart rate. The pulse beat was palpated in all cases at the subjects' wrist. The post-activity heart rate (peak heart rate) was measured by counting the time for twenty pulse beats immediately after each walking or running activity in the sitting posture on a chair. In this case, two recorders took the time for twenty pulse beatsone for the left hand and the other for the right and the mean of these two values was recorded. Factors, which affect the heart rate, such as smoking, ingestion of food, emotion and the thermal environment were explained to the subjects before the study was undertaken and the necessary precautions were taken accordingly for the first three factors. As regards the effect of temperature, all the subjects were exposed to the same environmental changes (slight rise of temperature only) and as such would have been similarly affected. 2.2. Stair climbinq A smaller group of subjects climbed up a staircase without any load. The staircase in Hostel No.2 of the Bhagalpur College of Engineering, where the subjects normally reside, was chosen so that no psychological factor would presumably affect the postactivity heart rates. The test was conducted in the morning hours in the post-absorptive periods. The staircase leading to the first floor from the ground floor has one halflanding in the middle. All subjects were asked to follow the same pattern of climbing up the steps and to negotiate the turning in the half-landing in the same fashion by not taking too large a path radius. The rise and tread of the steps were measured in the same way as in the walking or running activities. 2.3. Baithaki exercise The same group which took part in the stair climbing participated in the Baithak i exercise. The experiments took place during the morning hours in the post-absorptive periods. This exercise was conducted at three speeds of increasing Baithuk i cadence (number of Baithakis per minute). The time for twenty Baithakis was noted by timekeepers and the mean value recorded. Pre- and post-activity heart rates were measured us before. Energy consumption has been reported to bear a straight line relationship with heart rate ratio as described by Ganguli, Bose, and Datta (1976). The same relationship has been used here for the determination of' energy cost' in all the four activities. The relationship is given by E = 4'187(6 HRR - 5'1),
where
E= energy consumption (kJ min -I). and HRR
Heart rate ratio Peak heart rate (Post-activity heart rate) Resting heart rate (Pre-activity heart rate)
1234
R. N. Das and S. Ganquli
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It may be pointed out here that the above relationship was obtained in the estimation of energy cost in walking without any load and with graded loads only at a speed of 0·83 m S-I (3 km h-'). In the present study the same formula has been applied to calculate the energy cost of subjects walking or running without any load but at a much higher rate (maximum speed 6·7 m S-I (24,2 km h- I)) and performing other activities (stair climbing and Baithaki exercise).
3. Results and discussions 3.1. Walkint; and runninq actiuit v Table I provides detailed information regarding the height, weight and resting heart rate of the subjects. Table 2 presents the results obtained in respect of the speed, cadence, step length, heart rate ratio (HRR), percentage increase in postactivity heart rate ratio over pre-activity heart rate (%PHR) and energy consumption characteristics for the activities of walking and running. Tables 3 and 4 contain similar data for the activities of stair climbing and Baithak i exercise respectively. Plots of dependent variables like heart rate ratio (HRR), percentage increase in post-activity heart rate over pre-activity heart rate (%PRR), energy consumption E (kJ min-I), specific energy consumption E* (kJ kg-' min-I), and step length L (m) have been shown in the ordinate (Y -axis) against the three parameters, speed, V (km h - I), specific speed, V* (statures s - I), and cadence (C) in the abscissa (X-axts) for the sake of comparative study in Figures 2 to 7. Figure 2 shows that speed V and cadence C had a non-linear relationship throughout the whole range of walking to running 1-4-6'7 m S-I (5:...24 km h- 1 ) whereas specific speed (stature s -') had a linear relationship with cadence, which suggests that both specific speed and cadence may serve equally well as independent observable gait parameters contrary to speed. Figures 2 and 3 show that, within the absolute speed range 1·4-6·7 m S-I (5-24 km h- I), the energy consumption and speed V Table I.
Physical details of the subjects.
Age (years)
Sex
Height (m)
Barefooted weight (kg)
3." P. N. Singh 4. B. K. Choudhary 5. R. C. Ravidas 6. S. G. Ahsan 7. S. K. Sinha 8. S. S. Prasad 9. B. Thakur 10. S. S. P. Singh II. V. L. Shrestha 12: S. K. Gurung 13. H. Shrestha 14. S. R. Rizal 15. 1". H. S. Singh 16. M. A. Samad
25 26 26 25 29 24'5 24·5 31 24 25 23 24 21 23 J9 20
M M M M M M M M M M M M M M M M
1·725 1'63 1·66 \·712 1·59 1'62 1·73 1'67 1'80 1·73 ),70 J.7) 5 ),64 1·605 \·67 1'76
60 53'5 68 57 52'5 65 66 78·5 60'5 59·5 59 65·5 50·5 52 54·5 54·5
17. T. C. Prasad
38
M
1'63
56
1·68 (± 0'056)
59-56 (± 5'714)
SI. No.
Name of subject
I. A. Pandey 2. N. Puswun
Place of
Resting heart rate (beats
normal residence
min-I)
Indian plains Indian plains
64-86 63'15 70·00 66'66 70·96 64'17 74·07 67·00 70·00 63'15 74'53 74·07 74'53 61·85 61·22 64'17
Indian plains Indian plains Indian plains Indian plains Indian plains
Indian plains Indian plains lndian plains Nepal Tarai Nepal Tarai Nepal Tarai Nepal Tarai Nepal Tarai
Tripura (Indian hilly terrain)
Arithmetic mean: Standard deviation:
25'17 (± 4'27)
Indian plains
56'00
5.
4.
3.
2.
I.
10418 ( ±0·184) 1·98 (±0·127) 4·15 ( ±0·267) 5·765 (±0·51) 6·72 (±Oo43)
5·128 ( ±0·673) 7·13 ( ±Oo455) 1495 I ±0·949) 20·76 (± 1·84) 24·2 (± 1·54)
S-l
m
km h- I
VI
Mean speed
0·854 ( ±0·087) 1·24 ( ±0·065) 2-485 (±0·14) 3-26 ( ±0·27) 4·06 ( ±0·268)
statures 5- 1
V'
N.B. Figures under bracket denote standard deviation.
S. No.
V 119-42 (±5·31) 136·3 (±7-81) 175-6 (±6·14) 200·6 ( ±9·348) 231·7 (± 16·5)
C
Cadence
Mean
Table 2.
1·548 (±0·212) 1·698 (±0·20) 2·01 ( ±0·203) 2·158 ( ±0·2ISl 2-48 ( ±0·26Il
HRR
Mean 16·748 (±4-31)
54·07 (± 19·8) 72-84 (± 19-49) 102·10 (±21·05) In·50 I± 1986) i 52·0 (±25·0) t ±4·81) 30·73 ( ±4·31) 35-54 (±5·6) 38·52 ( ±8·79)
noo
kJ min-I
E
0·322 ( ±0·142) 0·397 ( ±0·104) 0·565 ( ±O·129) 0·657 (±0·146) 0·782 (±0·167)
kJ kg- 1 min-I
E'
Energy consumption
%PHR
Mean
Walking and running activities.
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O·g~O
( ±0·0271 10434 (±O·O72) 1·6X3 ( ±0·082) 1·73 ( ±0·067)
L*
( ±0·058) 1·04 ( ±0·022)
0·~g2
0442 ( ±0037l 0530 ( ±0·0269) o·g) 1 (±O·O481
Step length
0·761 ( ±0·059)
L m
'""
W
N
is· =:
(5
g
s-
§
=:
§"
~
Co
'"
iii ..,
..,
s'"
":::
g
Co
=:
:2.
'5·"
~
~
"
.~
'"
~.
::p §" ~
R. N. Das and S. Ganquli
1236
Table 3.
mean HRR
(kJ min-I)
PHR
0'861 ( ±0'068)
1·76 (±0'166)
22-86 ( ±3'97)
76·0 (± 17'52)
Energy consumption
Table 4. SI. No. Mean Baithaki Cadence
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3.
of
Baithaki Exercise. Energy consumption
%increase
Mean HRR
(kJ min-I)
ofPHR
1·706 ( ±0'088) 1'835 (±0'107) 1'92 ( ±0'204)
21'56 (±1·84) 24'74 ( ±2-67) 27'00 (±5'191)
71
26'43 ( ±5-68) 39·22 (±6'98) 52-96 ( ±3-82)
2.
% increase
Mean Ascending Velocity km h- I 0·239 (±0'019)
I.
Stair Climbing.
83 92
Figures under bracket denote standard deviation.
1'2
*
1'0
*~
L
o-e
..-"
...-.l:J,_._-~
....-.~.~·-"·L x.. _~_ . . -x------_x
0'6
t
0'4
*>
s-:......... a 3
_---1-0...J
x.......... x ...
0'5
2
>
'0
110
190
210
230
C ----
Figure 2.
Variation of speed, specific speed, step length and relative step length with cadence.
HRR \.
..tJ.-------s->:"
OfoPHR ,,
o-" " -0-- - ; .
"0
E\.
_ -o-
-----If"- _----~ _-0
-0--"
cc
it
100 40
30t 20'"
t
110
Figure 3.
t
ISO
_-'"t1""---
Variation of HRR, %PHR, Eand E- with cadence.
"
Preliminary observations on parameters of human locomotion
1237
t
*~
25 20
t
15 > 10
2
3
4
SPECIFIC SPEED
Figure 4.
v*_
5
Variation of speed, step length and relative step length with specific speed of walking and
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running.
0'8
0'7
125t 1000::: I n,
75", 0·3 SO
o
2'0
1·0
3'0
4'0
SPECIFIC SPEED
Figure 5.
5'0
V* ~
Variation of HRR, %PHR, E and E· with specific speed of walki'f and running.
~2'0"r
t '" c,
I
'"
1'5 0'50
HRR \
x
A: sr"
" " ~ _,c,-,-.%PHR X," '" x ; , ' -»
.F' r:f
L"" -",/'
E .......
40 2'0 1'5
"0 0'5
t
35 30
~
25
t w
20 15
Figure 6.
Variation of HRR, %PHR, step length and E with speed of walking and running.
R. N. Dos and S. Ganquli
1238
ID
IS
20
25
SPEED V ~
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Figure 7.
Variation of relative step length. L· and E* with speed of walking and funning.
(km h -I) relationship was non-linear, though with cadence the energy consumption relation was linear at first but became non-linear at higher cadence values. Contrary to this, specific energy consumption increased linearly with cadence as well as with specific speed (Figure 5). However, both these observations presumably would restrict themselves to a group of persons having little or no variation in stature and body weight as was the case in the present investigation. To establish the general validity of these findings, it would be necessary to apply the same tests to different groups of subjects having different heights and weights. Figures 2 to 7jointly convey that although absolute speed V increased with cadence in the beginning with slow running and consequently energy consumption E (kJ min - I) also increased linearly with cadence, with a further increase of cadence, speed V and energy consumption E appeared to rise rather slowly, nevertheless, the specific speed V* (statures s" I) and specific energy consumption E* (kJ kg- 1 min - I) continued to rise linearly with cadence. Two reasons can perhaps be attributed to explain the above fact: (a) Figures 2 and 4 show that step length L did not increase linearly with cadence (or specific speed) at higher running speeds; thus speed which is a function ofthesrroduct of cadence and step length, cannot increase at such a rate as it did at slow running speeds; and (b) the specific energy consumption continued to increase with cadence or specific speed as the body movement is faster at an increased cadence and thus energy must be expended in the increased activity condition. This suggests that, cadence or specific speed in the case of the group studied appeared to be more representative as a gait parameter than speed of locomotion. Figures 3 and 5 respectively show a linear relationship between heart rate ratio HRR and cadence C and HRR with specific speed V*. Similar relationships exist between %PHR and cadence or specific speed (Figure 4). This suggests that %PH R can also be used as an index of energy cost as well as HRR. The plot of %PHR and HRR on a speed base has been seen to be non-linear (Figure 6) and this indicates once again the inefficiency of speed as a gait parameter compared to cadence or specific speed in the group of subjects of the present investigation. The specific energy consumption,E* (kJ kg-I min-I) has a linear relationship with specific speed V* (statures s-') up to 4 statures S-I (equivalent speed 6·7 m s-' (24'2 km h- I )) , where~s the energy consumption, E (kJ min-I) and speed, V (km h- I ) relationship is linear up to 1·8 m S-I (6'5 km h-') only. Thus a single linear relation between specific energy consumption and specific speed (from walking to running) can be obtained for the whole range of human locomotion on the level.
Preliniinarv obseroations on parameters of human locomotion
1239
However, as pointed out already, this hypothesis needs to be validated by extending the investigation on more subjects of different heights and weights.
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3.2. Stair climbinq Table 3 shows the mean value of ascending speed 0·066 ± 0·005 m S-1 (0,239 ± 0·019 km h - 1) with a corresponding mean value of HRR (I. 76 ± 0'166) and energy consumption (22'87 ± 3'97) (kJ min - '). This exercise could not be carried out at different speeds because of many practical difficulties, such as danger ofslipping while climbing at higher speeds and exhaution of the subjects after a few steps had been climbed at higher rates of climbing. However, the small magnitude of the standard deviation of the mean values, based on a sample of 5 subjects did show consistency of results. 3.3. Baitliak! exercise Figure 8 shows the mean values of %PH R, HRR, and energy consumption E as a function of the Baithaki cadence. As expected, the relationship is linear in all the three cases confirming that cadence is the governing parameter, not only in gait-study but possibly in other human activities also where a rhythmic type of work is involved. On inspection of the Human Locomotion Chart in the Appendix it is apparent that, out of various parameters relevant to locomotion, only a few have been covered so far. Interrelationship among other parameters, like step length L, subjects' height H, cycle time T. or cadence C seem to be straightforward. The simple fact of experience suggests that tall people normally take longer steps at a slower cadence and short persons take shorter steps at an increased cadence. Hence, the value of the ratio THI2L was calculated for walking activity only. It was observed that values of the quantity K = THI2L became almost constant for 17 subjects (K = 1·07 ± 0,06). Similarly the value of the Ponderal Index
PI
=
H
ijW'
where H
= Height of the subject (m)
W
=
Weight of the subject (kg)
for the first 10 subjects gave a mean value of 0·4319 ± 0·09.
28
22
20
30
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R. N. Das and S. Ganquli
4. Conclusion This investigation has shown, although in a limited way, that cadence and specific speed would emerge as relatively more useful gait parameters with which most of the other dependent observable parameters can suitably be related. Cadence is easy to measure with a stopwatch and even without the knowledge of the subject being observed, and has an added advantage over other parameters such as speed where accurate measurement of distance and time is required. This is particularly relevant in the context of work measurement where rating the performance of an individual worker engaged iii a rhythmic activity, in terms of speed of walking (as is done today throughout the world) poses perceptual problems and thus becomes an unrealistic and futile exercise. Visualizing a physical work rhythm in terms of cadence is much more objective. This study has also highlighted that as a standard basis of energy cost, the unit should always be in kJ kg-' min - I for better rationality. This investigation has indicated that speed would also be expressed in terms of statures s-, (instead of conventional unit km h - 1 or m s - '). However the suggested unit of speed in statures s -, may not be appreciated quantitatively at the beginning by many, as it does not give a correct idea of how fast or slow the subject is moving. Therefore it is proposed that with the conventional unit of speed in m s - I. or km h - I, the non-conventional speed in statures S-I should be mentioned in parenthesis. It could perhaps be used on a trial basis for comparison of different speeds of activity in rating workers in Industry and Agriculture. The importance of cadence as a governing parameter has been confirmed in another activity like the Baithaki exercise and hence can also be generalized for other repetitive work. A distinct limitation of this preliminary investigation has, nevertheless, been the larger standard deviations of some of the parameters (Tables 2, 3, and 4). This could be avoided by taking larger samples and improved experimental procedures, which the authors propose to incorporate in their future work.
V'"
V
,
H
Specific speed (statures
S-I).
Weight (bare-footed) of a subject (kg). Height or stature (bare-footed) of a subject (m). Step length, stride length (m).
W H L
L*
Glossary Walking Running speed on level ground (km h - '). Walking/Running speed on level ground (m S-I).
L H
T
C RHR PHR %PHR PHR HRR = - RHR E
Relative step length. Time period for one cycle (s). Cycle time. Cadence (Number of steps per minute). Pre-activity Heart Rate (Resting Heart Rate) (beats min -') Post-activity Heart Rate (Peak Heart Rate) (beats min - [). Percentage increase in PHR over RHR after any activity. Heart Rate Ratio. Energy consumption (kJ min - ').
Preliminarv observations E* =
E
W H K= 2L
Be
parameters of human locomotion
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Specific energy consumption (kJ kg-I min -I). A constant (characteristic of level walking). Baithaki Cadence (No. of Baithakis min - I).
H
P1=
011
Vw
Ponderal Index.
Une recherche pre-liminaire sur Ie terrain a etc effectuee sur J 7 sujets adultes masculins afin de determiner
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les parametres importants concernant la marche, ainsi que les relations qui existent entre eux. Des termes nouveaux leis que "vitesse specifique", "consommation specifique d'energie" (kJ .kg- ' min -I) "pourcentage d'augmentation de la frequence cardiaque de pointe" et une grandeur sand dimension: "la longueur relative d'un pas" ont etC utilises. On a observe une superiorite de 1a cadence et de 1a vitesse specifique sur la vitesse, ainsi que de la consommation specifique denergie sur l'energie. De rneme une relation lineaire est apparue entre la vitesse specifique et la consommation specifique pour des vitesses allant jusqu'a 6,7 m.s- 1 (24 km.heure). Dans les comparaisons on a inclu l'ascension d'un escalier et des exercices de Baithaki qui constituent des taches rythmiques au meme titre que la marche. On suggere d'utiliser 1a cadence en tant que parametre observable Ie plus important pour la marche et la course ainsi que pour d'autres activites ryrhmecs. Les resultats peuvent ctre utilises pour l'etude du travail.
Eine experimentelle Voruntersuchung im Feld wurde mit 17 normalen erwachsenen Mannern durchgefUhrt, urn die wichtigsten wahrnehmbaren Parameter der menschlichen Fortbewegung und die Beziehungen, die zwischen ihnen bestehen, zu untersuchen. Neue allgemeine Ausdrucke, wie z.8. die spezifische Geschwindigkeit (S-I), der spezifische Energieumsatz (KJKg- 1 min -1), der prozentuale Anstieg der Herzschlagfrequenz, und ein dirnensionsloser Ausdruck, ntimlich die relative Schriulange wurden eingefUhrt. Eine Uberlegenheit der rhythmischen und spezifischen Geschwindigkeit i.iber der Geschwindigheit und eine Oberlegenheit des spezifischen Energieumsatzes i.iber dem Energieumsatz wurde beobchtet und es wurde eine einzige lineare Abhangigkeit zwischen der spezifischen Geschwindigkeit und dem spezifischen Energieumsatz bis zu einer Geschwindigkeit von 6.7 m s" I) (24 krn h ~ 1) festgestellt. Stufensteigen und Baithaki Ubungen wurden a1s zwei weitere rhythmische Tatigkeiten wegen des Vergleichs mit der Fortbewegung mit eingeschlossen. Die Verwendung des Rhythmus als ein verhaltnismabig wichtigerer wahrnehmbarer Gangparameter wurde filr Geh- oder Laufbewegungen ebensogut wie fur andere rhythrnische Tatigkeiten vorgeschlagen. Diese Untersuchungen haben fur die Anwendung im Bereich yon Arbeitsstudium und Industrial Engineering Moglichkeiten.
References BARD. G.. and RALSTON. H. J., 1959. Measurement of energy expenditure during ambulation with special reference to evaluation of assistive devices. Archives of Physico! Medicine and Rehubilitutinn, 40, 415-420. DURNIN, J. V. G. A., and PASSMORE. R., 1967, Energy Work and Leisure (London: HEINEMAN EDUCATIONAL BooKS).
GANGULI, S., t 973, Observations on the basic gait characteristics of Indian Industrial Workers. Indian Journal of Industrial Medicine. 19,28-35. GANGULJ, S., BOSE, K. S., and DATTA, S. R.. 1976, A new method of energy evaluation in Rehabilitation clinics. I.S.P.O. Bulletin. 20, 4-5. GANGULI, S., 1977, Human Engineeringfor Belfer Munaqement, (Calcutta: KWALITY BOOK COMPANY).
GRIEVE. D. W.• and GEAR. H. J., 1966. The relationship between length of stride, step frequency. lime of swing and speed of walking for children and adults. Ergonomics, 9, 379-399. Introduction to Work Study, 1974. (Geneva: INTERNATIONAL LABOUR OFFICE). Fourth Impression. Manuscript received 28 August 1978. Revised manuscript received 9 May 1979. ERG.
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R. N. Das and S. Ganguli
APPENDIX I. 2. 3. 4. 5. 6. 7.
Name and occupation. Date. Time. Dry bulb temperature. Wet bulb temperature. Relative humidity. Age and sex.
H. Height (bare footed) (m). 9. Weight (bare footed) (kg) . . 10. Leg length: (a) hip joint to knee. (b) knee to the ground, and knee to ankle, (c) hip joint to the ground. II. Pre-activity resting heart rate (beats min -'). 12. Post-activity peak heart rate (beats min-')-
