Dear Biomch-l and Ortho-l subscribers:

Several weeks ago I posted a question to both biomch-l and ortho-l about
the risks of carrying backpacks on one shoulder. While much anecdotal
evidence exists, the research literature on this topic is scant. Below I
summarize the responses along with my original posting. A couple of people
pointed out to me that this same question had been posed by someone else on
biomch-l last May. Readers are encouraged to look at that summary posted
21 May 1995 for extra information. Thanks to all who replied to my

======Original posting========

Is it harmful to carry a backpack only on one shoulder (as many school
children do)? Is the asymmetrical loading produced by this behavior
bad for the spine or other areas of the body? Has there been any good
research on this topic? Any information you provide will be appreciated.

While I am not aware of any research regarding carrying backpacks
(although I honestly have not looked) I do know from my clinical practice
that occasionally, a male patient presenting with back pain will improve
markedly if he stops carrying his billfold in his back pocket. In sitting,
the pelvic asymmetry that's created, particularly if the wallet is thick,
may be enough to produce symptoms. A parallel thought to your question.

Barbara Loitz-Ramage
Department of Kinesiology
University of Wisconsin-Madison

Hi Dr Hinrichs,
Such a question was asked on the Physio-L in the last 12 months. I
would suggest that you take a look at their archives. The list is
situated on
If you have any problem connecting with those archives I will gladly
Good luck.

Michel Ladouceur, PhD(c)
McGill University
School of P.& O.T.
3630 Drummond, Room 105
Montreal (Quebec)
H3G 1Y5
Tel: 514.398.4519
Fax: 514.398.8193

There was a slide presentation at the 1994 (Indianapolis) ACSM
meeting on this subject. In addition there was a posting to BIOMCH-L
within the last year about this issue. Try the proceedings and then the
archives of BIOMCH-L for further info. Good luck. I know this is a
problem, someone should find some answers - both short and long term.

Jon Fewster
Biomechanics Lab
Oregon State University

Here are some references concerning carrying schoolbags :

Pascoe DE. Impact of book bags on gait cycle & posture. In Medicine
& Science in Sports & Exercise, abstract nr. 787, supplement to vol
26, 5 May 1994

Malhotra MS & Sen Gupta. Carrying schoolbags by children. In
Ergonomics 8, p 50-60

Vozenilkova H et al. Investigation of the effect of the weight of
schoolbags and other fators on the posture of children.
Ceskoslovenska Hygiena 1988, 33/7-8, p 419-425.

For more information : (Claartje ten

This is part of a list from a message on 21 May 1995

I hope this will help you further,

Veerle Hermans

You will probably receive many copies of this suggestion, but I suggest
that you search the biomch-l archives for messages related to this
topic, which was discussed a few months ago. I cannot remember
exactly when.
| Amy C. Courtney, Ph.D. |
| Dept. of Biomedical Engineering |
| The Cleveland Clinic Foundation |
| 9500 Euclid Avenue |
| Cleveland, Ohio 44195 USA |
| |
| |

Hello Mr. Hinrichs,
You have posted a question that is of personal interest to me. I have
a mild case of scoliosis, which is evident in the dramatic difference in
height of my shoulders. For a good portion of my adolescent life I
walked long distances (to school, barefoot, ten feet of snow, etc.)
carrying a gym bag or back pack over one shoulder. I also worked as a
paper boy; again, asymmetrical loading. Consultation with a
chiropractor led to the conclusion that these activities were probably a
significant factor in the develop of my postural problems.
When a person carries the load on one shoulder, they have to activate
the musculature in the shoulder girdle region to maintain the loaded
shoulder near the same posture as the unloaded; this facilitates easier
walking. Daily loading of one half of the body results in increased tension
and strength in those muscles, which could lead to unequal loading of the
spine. I believe that this type of activity will affect people
adversely, especially young people whose bodies are still developing, and
persons carrying heavy loads regularly.
All this is purely my opinion and thoughts on the matter. Two areas
that I would suggest you look into is research dealing with the military
and with the postal service. In my work with Canada Post, I had access to
many internally produced projects dealing with letter carriers, and noted
some other references from the military. If you have access to an
ergonomics group within the American postal service, I would guess they
have done some work on this also.
Good luck with your search,

David M. Brodie
Graduate Student/MSc. Occupational Biomechanics
University of Waterloo

There has been some work done on this by Don Neumann, PhD, PT. He is
currently at Marquette University. I believe an article appeared in the
journal PHYSICAL THERAPY in the late 80's or early 90's. His findings
related to arthritic changes in the hip from asymmetrical loading.
Hope this helps.


Scott D. Minor, Ph.D., P.T.
Program in Physical Therapy
Washington University School of Medicine
Box 8502, 4444 Forest Park Blvd.
St. Louis, MO 63108
(314) 286-1432 (voice)
(314) 286-1410 (fax)

I don't know for sure, but when I was a kid you were considered a geek
to use both straps. I suppose there is some harm using two straps too,
unless it is true, as it must be in my case, being an engineering student
(Geek by default).
Good luck!


Interesting topic. My thought are yes, it's not good. I have no supporting
science. Personally, however, I went throgh a heavy one-shouldered-lugging
period during my undergrad years. I think between that and the stress it
did wonders for my neck and back. Permanent? I don't think so, but I was
pretty much done growing by then.
Anyway, the reason I write is to ask if you've posted to Ortho-L.
That may be a good cross-post for this question.

Good luck. I await your summary.


[Note: I (rnh) did post to ortho-l and some of the replies here came from
that list.]

Dear Rick,
One of my students finishes her report about the same subject.
She has done a literature study in combination with a field study.
The field study consisted of a visit to two secondary schools,to observe
and question the students (actual about 100 students have filled in a
questionaire), to measure some anthropometrics.
If this would be useful to you(r student), please let me know.
With kind regards,

Johan F.M.Molenbroek,PhD
Associate Professor Engineering Anthropometry
Deputy Subdepartment Physical Ergonomics
Faculty Industrial Design Engineering
Delft University of Technology
Jaffalaan 9
2628 BX Delft, The Netherlands
voice + mailbox:+31-15783086
voice secr +31-15783029

[Note: I (rnh) replied to Johan Molenbroek and asked for more information.

Dr. Molenbroek sent a draft of a manuscript in preparation which contained
many references. While I do not think it is appropriate to include the
manuscript here, I am listing the references below. Contact Dr. Molenbroek
for more information.

1. Vozenilkova, H. et al. Investigation of the effect of the weight of
school bags and other factors on the posture of children. Ceskoslovenska
Hygiena, 1988, 33/7-8, p. 419-425.
2. Pearsall, D.J. and Reid, J.G. Line of gravity relative to upright
vertebral posture. Clinical biomechanics, 1992, 7/2, p. 80-86.
3. Beker, M.C. und Schlegel, K.F. Schultasse und haltung. Kinderheilkunde
92, 1965, p. 7-14.
4. Voskamp, P. Handboek van de ergonomie, 1991, p.49-55.
5. ARBO 1993 jaarboek, 1993, p. 439,447.
6. Mital, A. et al. Legislation of various countries addressing the
problems of MMH. A guide to manual materials handling, 1993, p.5-7.
7. Vink, P. Van den Berg, R. Dul, J. Het beoordelen van tillen met de
nieuwe NIOSH-methode, Tijdschrift voor de Ergonomie, 1992, 10, p. 2-9.
8. Vink, P. Smitt, P. Van den Berg, R. De nieuwe NIOSH-methode (II),
Tijdschrift voor de Ergonomie, 1993, 8, p. 7-11.
9. Arbeidsomstandighedenbesluit Onderwijs, 1991, H 1-34-1-H 1-34-5.
10. Kettner. G. Biogeographica, volume 3, 1973, p.13-15;129;135;145-146.
11. Wespi, H. Schulartzliche beurteilung der wirbbelsaulenschaden.
Rheumatismus in forschung und praxis II, 1964, p.119-130.
12. Kemper, H.C.G. Growth, health and fitness of teenagers, Medicine and
sport science vol. 20, 1985, p.129;140-149.
13. Hazebroek, A.A.J.M. Trunk abnormalties in adolescence, 1993, p.119-121.
14. Frankel,V.H. Nordin, M. Snijders, C.J. Biomechanica van het
skeletsysteem, 1984, p.284-294.
15. Garg, A. Maximum acceptable weights and maximum voluntary isometric
strengths for asymmetric lifting. Ergonomics, 1986, vol. 29, no. 7, p. 879-
16. Burton, K. Spinal strain from shopping bags with and without handles.
Applied ergonomics, 1986, 17.1, p.19-23
17. Martin, P.E. and Nelson, R.C. The effect of carried loads on the
walking patterns of men and woman. Ergonomics, 1986, vol. 29, no. 10, 1191-
18. Legg, S.J. and Mahanty, A. Comparison of five modes of carrying load
close to the trunk. Ergonomics, 1985, vol.28, no.12, 1653-1660.
19. Kinoshita, H. Effects of different loadsand carrying systems on
selected biomechanical parameters describing walking gait. Ergonomics,
1985, vol.28, no.9, 1347-1362.
20. Datta, S.R. and Ramanathan, N.L. Ergonomic comparison of seven modes
carrying loads on the horizontal plane. Ergonomics, 1971, vol.14, no.2,
21. Eveland, E. et al. Stooped vs. squat lifting techniques. CSER/AC
Gateway, 1994, vol V, no.2, p.14-15.
22. Malhorta, M. And Sen Gupta, J. Carruing of schoolbags by children.
Ergonomics 8, 1965, p.55-60.
23. Pascoe, D.E. et al. Impact of book bags on gait cycle and posture.
Medicine and science in sports and exercise, 1994, vol.26, no.5, p.140.
24. Levick, P. Bailey, M. and Mitchell, J. Posture at school and at work.
Can we change it? Ergonomics, technology and productivity, proceedings of
the 25th annual conferenceof the ergonomic society of Australia, 1989,
25. Vanickova, E. and Karnikova, R. Disorders of the locomotor apparatus in
junior school children. Cesko-Slovenska Hygiena, 1993, nr.38, p.233-238.
26. Smith, J.L. and Jiang, B.C. A manual materials handling study of bag
lifting. American Industrial Hygiene Association Journal, 1984, no.45,
27. Holewijn, M. Physiological strain due to load carrying. European
Journal of Applied Physiology, 1990, p.237-245.
28. Dukes-Dubos, F. What is the best way to lift and carry? Occupational
Health and Safety, 1977, no.46, p.16-18.
29. Kyral, J. And Emr, J. New types of lighter school bags for prevention
of poor posture. Acta Chir. Orthop. Traum., 1986, no.6, p.542-546.
30. VozenIlkova, H. Vanickova, M. and Jerabkova, A. A contribution to the
problem of weight of satchels in compulsory schools. Cs. Hug., 1977, no.3-
4, p.153-157.
31. Grimes, P. School pupil posture. Ergonomics; design for usability.
Proceedings of the 4th conference of the New Zealand ergonomic society,
Palmerstd north, 1992, 26-27 march, p.62-67
32. Amsterdams groei en gezondheidsondeerzoek. Nederlandse jongeren bewegen
minder dan goed voor ze is. Volkskrant, 1995, 28 juli, p.16.

Hi Rick,
Your note was forwarded to me from a mech e pal of mine here at the
Ergonomics program at Berkeley. I am one of the grad students here at
Berkeley and my background is in physical therapy. I know that the
metabolic demands of 1 armed carrying are higher. Grandjean and Kromer
both have ergonomics text that would reference that issue. Also the
effect of assymetrical carrying is a frequent issue clinically in
treating patients with neck, back and UE problems. Your question may be
covered in Physical therapy journals too.

Meg Honan

I have wondered about that myself, mostly since I've done it a long
time and get cervical pain and tightness. If you don't mind, please
pass on anything interesting to me.

************************************************** *****
Douglas J. Adams
Orthopaedic Surgery
The University of Iowa
************************************************** *****

--- You wrote:

Heavy asymmetric loading is associated with persistent changes in body
shape/size. The evidence for this includes mild scoliosis in oars-people
using a sweep in late adolescence, and tennis players, with marked
assymetry of the arms, the dominant arm being larger. Hand dominance can
often be ascertained on exam by comparing the width of the base of the
thumb-nail, which will be wider on the dominant hand.

My expectation, from clinical experience, would be to discount the practice
of heavy back-pack carriage as a source of persistent clinical difficulty.

None of which I am aware. Spine is a journal that might be worth

Dr. Michael Mayor
Professor of Surgery in Orthopaedics
Dartmouth Hitchcock Medical Center
Hanover, NH

I am not aware of any good dtudies related to this problem. In general it
has been a clinical observation that the shoulder and surrounding
structures increase their mass during the time this function is occuring.
Some have a clinical impression that it remains afterward but this has not
been proven. While it this activity occurs it is often obvious that one
shoulder is higher the child may lean to that side and the back can look
curved. However these are all what is termed functional changes - and there
is no evdence thast it leads to permanent changes or any pathological
processes. Often parents of many children who have scolioses consider
that this is the cause of it. True scolioses that requires treatment has a
curve much more severe than the functional curve that is present from
assymetric loading of the shoulders and shows many pathological changes in
the spine even very early in the process not found in these children who
have the habit of assymetric loading. By all indications it is entirely a
different problem.

Dear Rick,
I have only personal anectdotal evidence that single-shouldered backpack
carrying can cause changes, but I would assume that many others have made
similar observations. I carried my backpack on my left shoulder throughout
undergraduate and graduate school (11 years). Shortly after graduating, I
participated in a motion study which involved a brief screening for body
symmetry and alignment. Somewhat to my surprise, I was told that my left
shoulder was elevated (and hypertrophied) significantly above my right, and
thatthe malalignment extended down to my left calcaneus! I have not
carried a backpack for the past three years now, and there does not appear
to have been any permanent changes. I would be very interested to hear
whether anyone else has made (or been the subject of) similar observations.

Scott Banks, PhD
Orthopaedic Research Laboratory
Good Samaritan Medical Center
West Palm Beach, FL

Thanks to all who replied.


Richard N. Hinrichs, Ph.D.
Dept. of Exercise Science
Arizona State University
Box 870404
Tempe, AZ 85287-0404 USA
(1) 602-965-1624 (office)
(1) 602-955-8108 (fax) (email)