Muri
無理·muri·"unreasonableness, impossible"
Personalize This
Get insights for your role
Muri refers to overburden or unreasonable stress placed on people or equipment beyond their capacity.
Definition
Muri is the Japanese term for overburden, strain, or unreasonableness—placing excessive demands on people, equipment, or systems beyond their sustainable capacity. While muda focuses on waste and mura on unevenness, muri addresses the stress that leads to breakdowns, injuries, errors, and burnout. Muri often results from mura (peaks in uneven workloads) or from poorly designed processes that require unnatural movements or unsustainable pace. Eliminating muri is both a practical concern for quality and reliability and an ethical imperative under the lean principle of respect for people.
Examples
An assembly station required operators to reach overhead 400 times per shift to retrieve parts, causing shoulder strain and repetitive stress injuries. This muri was eliminated by repositioning parts at elbow height, reducing injuries to zero and improving cycle time as the ergonomic motion was faster.
Key Points
- Muri creates defects, equipment failures, injuries, and employee burnout
- Sustainable pace, not maximum speed, produces the best long-term results
- Standard work should be designed within human and equipment capabilities
- Respect for people requires eliminating conditions that harm workers physically or mentally
Common Misconceptions
Pushing harder increases output. Short-term gains from overburden are offset by quality problems, equipment failures, and human costs. Sustainable operations at appropriate pace consistently outperform heroic efforts.
Muri only applies to physical work. Knowledge workers experience muri through excessive cognitive load, unrealistic deadlines, and constant interruptions. Mental overburden causes errors and burnout just as physical overburden causes injuries.