What do people get wrong about heavy bags and the strain on the body?
This answer is a draft. It stays unpublished until legal review and source verification are complete.
Carrying a heavy bag on one shoulder every day is discussed worldwide as a cause of stiff shoulders and poor posture. In Japan, commuters and students carry heavy loads, and the weight of children's *randoseru* (the rigid school backpack used by primary pupils) became a public issue. This article sets out the official guidance and what people do about it.
Numbers and guidelines
| Item | Detail | Source |
|---|---|---|
| Guide weight for a bag | 10–15% of body weight or less (for children 10% or less is given as an international guideline) | American Academy of Pediatrics; orthopaedic guidance in various countries |
| Randoseru | Average about 4–6 kg (textbooks and tablet included). Can exceed 20% of a first-year pupil's body weight; in 2018 the Ministry of Education (MEXT) issued a notice allowing "oki-ben" (置き勉, leaving textbooks at school) | MEXT (the notice); the weights come from private surveys |
| Commuter bag | Often 3–5 kg with laptop, water bottle and papers | — |
| Effect of one-shoulder carrying | The shoulder rises, the neck and shoulder muscles tense, the trunk tilts. One factor in stiff shoulders and headaches | Standard orthopaedic explanation |
| Fixes | Alternate sides, backpack (both shoulders), cross-body strap held close to the body, shorten the strap (bag above the hips) | As above |
- In September 2018 MEXT notified schools nationwide that pupils may leave textbooks and other items at school ("oki-ben"). The background was heavier randoseru and children complaining of back and shoulder pain.
- A backpack spreads the load over both shoulders, but if the straps are long and the bag hangs below the hips, the strain on the lower back increases. A chest strap adds stability.
- On a crowded train, wear your backpack on your front (see the article on train etiquette).
[Verify] Check the MEXT notice (September 2018, "On consideration for items carried by pupils and students") and the source for the weight guidelines.
Misunderstanding 1｜You get used to the weight
Muscles may adapt, but a continuous load on one side is generally described as affecting posture and neck-shoulder tension. Simply swapping sides makes a difference.
Misunderstanding 2｜With a backpack, any weight is fine
Above 10–15% of body weight it is a burden. Shorten the straps, keep it against your back, use the chest strap.
Misunderstanding 3｜A child's randoseru cannot be made lighter
MEXT allows "oki-ben". Talk to the school and reduce what comes home every day. Some schools got heavier when tablets were introduced, so check.
Misunderstanding 4｜A cross-body bag is one-sided too, so it is the same as a shoulder bag
A cross-body bag sits against the body and spreads the weight across the trunk, so it is generally described as less strain than a shoulder bag. Swapping sides still applies.
Misunderstanding 5｜To lighten your bag, buy a new one
Go through the contents first. Take out "things I do not use every day", carry a smaller water bottle, leave the laptop charger at work — tips shared among Japanese commuters. Look at the weight of the bag itself, too (leather can be over 1 kg).
---
Sources
- Ministry of Education, Culture, Sports, Science and Technology (MEXT), "On consideration for items carried by pupils and students" (administrative notice, 6 September 2018) [文部科学省「児童生徒の携行品に係る配慮について」（平成30年9月6日 事務連絡）]
https://www.mext.go.jp/a_menu/shotou/new-cs/
- Japanese Orthopaedic Association, "Stiff shoulders and posture" [公益社団法人日本整形外科学会「肩こり・姿勢」]
https://www.joa.or.jp/public/sick/
- Consumer Affairs Agency, "Safety of children's school bags (randoseru)" [消費者庁「子どもの通学用かばん（ランドセル）の安全」]
https://www.caa.go.jp/policies/policy/consumer_safety/child/
- American Academy of Pediatrics (AAP), "Backpack Safety" (HealthyChildren.org)
https://www.healthychildren.org/English/safety-prevention/at-play/Pages/Backpack-Safety.aspx
⚠️ Editorial note: the source URLs above were identified by search. Our working environment cannot reach go.jp domains, so the contents have not been checked against the text. Verify every source before publication and record who checked it and when.
About this article
What we share here are ideas and everyday practices passed down among people living in Japan, together with general information drawn from public sources. They are not official recommendations, and they are not professional instruction. Practices vary between households and regions.
This is general information. Results vary from person to person and depend on your own conditions and surroundings.
Please decide for yourself, using your own judgement, whether any of this suits your situation. We cannot accept responsibility for any damage, loss or injury arising from following this article.
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