Manually stacking boxes at great heights poses serious risks to employees’ musculoskeletal health. The combination of heavy loads, poor posture, and repetitive movements above shoulder height makes this one of the most physically demanding tasks in a warehouse setting. This article answers the most frequently asked questions about the hazards of manual stacking at height and what you can do about it.
What are the most common injuries associated with manually stacking boxes at height?
The most common injuries associated with manually stacking boxes are back pain, shoulder injuries, and wrist problems. Specifically, these include muscle strain in the lower back, rotator cuff injuries in the shoulder, and overuse of the tendons in the neck and arms. These conditions result from a combination of weight, poor posture, and repetitive movements.
When lifting boxes above shoulder height, the shoulder joint is forced into an extreme position, placing maximum strain on the stabilizing muscles and tendons. A box weighing just five kilograms feels many times heavier when held at arm’s length above the head due to the effect of leverage on the joint.
In addition to acute injuries such as sprains and muscle tears, there are also cumulative conditions that develop over weeks or months. Examples include:
- Tendinitis of the shoulder or wrist caused by repetitive stretching and lifting
- Cervical herniated disc resulting from prolonged neck strain
- Lower Back Pain Caused by Combining Lifting and Twisting
- Carpal tunnel syndrome caused by repeated forceful gripping with the wrist in an unfavorable position
In occupational medicine, these conditions are classified as musculoskeletal disorders (MSDs) and are one of the leading causes of long-term absenteeism in the logistics and industrial sectors.
Why does the risk increase as the stack height increases?
The risk associated with stacking boxes increases with height because the biomechanical strain on the body rises exponentially as the arms are raised higher. Above shoulder height, the body loses its most stable lifting zone, causing muscles and joints to bear a disproportionately heavy load, even when handling light loads.
From a biomechanical perspective, the optimal lifting zone for humans is between knee height and elbow height. Outside this zone, the strain on the spine and shoulder joints increases rapidly. When reaching overhead to the maximum, the effective load on the shoulder can be three to four times the actual weight of the box.
Additional risk factors that increase with altitude:
- Impaired vision: The employee can no longer see the stacking area clearly, which leads to uncontrolled movements
- Unstable grip: when the arms are outstretched, grip strength is significantly lower, making it easier for boxes to slip out of one’s hands
- Loss of balance: the body’s center of gravity shifts, increasing the risk of falling
- Fatigue builds up more quickly: the body cannot maintain the poor posture for as long, leading to an increase in errors
Box-handling operations in a warehouse are therefore most hazardous when the stack height exceeds the height of the employee's shoulders.
Less effort, more performance
Lift more efficiently with ergonomic lifting solutions. Our specialists are happy to work with you to find the right solution.
What does the law say about manually handling loads at heights?
Belgian law requires employers to assess and reduce the risks associated with manual handling of loads. This is set forth in the Codex on Well-Being at Work, which transposes European Directive 90/269/EEC into national law. Employers are legally required to implement technical or organizational measures whenever manual handling poses a health risk.
The law does not set absolute weight limits, but instead takes a risk-based approach. Factors that the employer must consider in its risk analysis include:
- The weight and size of the load
- The distance and height over which the load is moved
- The frequency and duration of the action
- The employee's body posture while lifting
- The employee's individual characteristics
If the risk assessment indicates that manual handling poses a health risk, the employer is required to provide technical aids as a first step. Only if this is not possible may organizational measures be implemented. Prevention advisors and occupational physicians play a central role in this process within the company.
How does repeatedly reaching overhead affect long-term health?
Repeated overhead reaching leads, in the long term, to chronic degeneration of the shoulder joints, known as impingement syndrome or rotator cuff injury. These conditions develop gradually and are barely noticeable in the early stages, causing employees to often ignore the symptoms for too long until major medical intervention is necessary.
Impingement syndrome occurs when the rotator cuff tendons are repeatedly compressed between the acromion and the humeral head. This process occurs in stages: first, irritation develops, then inflammation, and eventually the tendons may tear partially or completely. In severe cases, recovery requires surgery and months of rehabilitation.
In addition to the shoulder, prolonged overhead work also affects:
- The Cervical Spine: Chronic Neck Pain and Increased Risk of Cervical Disc Herniation
- The Elbows: Lateral Epicondylitis, Better Known as Tennis Elbow
- The hands and wrists: reduced grip and tingling caused by nerve compression
What makes these conditions particularly problematic is that they affect not only work performance but also quality of life outside of work. Everyday activities such as reaching for something on a shelf or raising one’s arm become painful, leading to a downward spiral of avoiding movement and further weakness.
What ergonomic aids reduce the risks associated with stacking boxes?
Ergonomic aids that reduce the risks associated with stacking boxes at height include vacuum lifters, mobile lifters, and electric hoists. These devices bring the load to the worker instead of requiring the worker to reach for the load, thereby drastically reducing the strain on the shoulders, neck, and back.
Choosing the right tool depends on the weight of the boxes, the desired stacking height, the available space, and the frequency of the operation. Some commonly used solutions:
- Vacuum lifters: ideal for boxes that are picked up using suction cups and precisely positioned at the desired height, without the employee having to carry the weight themselves
- Mobile lifts: platform lifts that raise the worker to the required working height, ensuring that lifting always takes place within the optimal zone
- Electric pallet trucks with a lift mast: suitable for moving and stacking heavy boxes on pallets
In addition to mechanical aids, workstation design and job rotation also play a role. By regularly rotating employees between tasks that engage different muscle groups, cumulative strain is minimized. A vacuum lifter or hoist can make the difference between a safe and a high-risk workstation.
When is manual stacking of boxes no longer advisable?
Manual stacking of boxes is no longer considered safe when the stack height exceeds the employee’s shoulder height, the weight of the boxes exceeds ten kilograms, or the task is repeated more than twenty times per hour. At that point, the ergonomic risks are too great to work without technical aids.
In practice, there are clear signs that manual stacking has reached its limits:
- Employees frequently complain of shoulder or neck pain after the workday
- There is an increase in absenteeism due to illness among the team that performs stacking work
- Boxes frequently fall while being placed at heights
- Employees use stairs or ladders to reach the top of the stack
- A large portion of the staff is unable to perform the stacking task due to physical limitations
If one or more of these signs are present, a thorough workstation analysis is necessary. After all, the law requires employers to take action as soon as a real health risk is identified. Waiting until an injury occurs is both ethically and legally irresponsible.
How Logitrans Handling Helps Ensure the Safe Stacking of Boxes at Height
At Logitrans Handling, we understand that the risks of manual stacking at height are not always immediately apparent, but can gradually build up to cause serious health problems and lost productivity. That is why we offer a comprehensive approach that goes beyond simply supplying a product.
- Free Workstation Analysis: Our specialists will analyze your specific stacking situation and identify the ergonomic risks
- Customized solution: Based on the analysis, we select the most suitable assistive device, whether it’s a vacuum lift, a mobile lift, or an electric hoist
- Try it out in the demo room: In our demo room in Drongen, you can test the solution with your own boxes to ensure you make the right choice
- Training upon installation: We ensure that your employees use the new device correctly and safely
- Maintenance Contract: With our maintenance contract, your equipment will remain in top condition and safety will be guaranteed
An investment in ergonomic aids is an investment in the health of your employees and the continuity of your business. Would you like to know which solution best suits your situation? Feel free to contact us for a no-obligation consultation.
Less effort, more performance
Lift more efficiently with ergonomic lifting solutions. Our specialists are happy to work with you to find the right solution.
