Manual Handling: Ergonomics and Risk Prevention

Manual handling of loads is one of the main causes of MSDs and lower back pain in the workplace. This article presents the ergonomic principles, weight limits, and mechanical aids available.

Manual handling of loads is one of the main causes of occupational accidents and diseases: musculoskeletal disorders (MSDs), lower back pain, and hernias. Its prevention involves the application of ergonomic principles, respect for weight limits, and the use of mechanical aids.

Definition

According to the French standard NF X 35-109 (Ergonomics — Manual handling of loads), manual handling refers to any operation of transporting or supporting a load weighing more than 3 kg, carried out by a single worker without mechanical assistance. It includes carrying, lifting, placing, pushing, pulling, and moving.

Associated Risks

The main risks are:

Lower back pain (pain in the lower back) — the leading cause of work stoppages.
MSDs of the upper limbs: tendinitis, carpal tunnel syndrome, epicondylitis.
Disc and abdominal hernias.
Falls when carrying bulky loads.

Ergonomic Principles

Several methods structure prevention:

RECO-2S (INRS): Simplify, Reduce, Consult, Organize.
NIOSH Equation (Revised NIOSH Lifting Equation, developed in 1991 and published in 1993 by Waters, Putz-Anderson, and Garg): Calculation of acceptable load based on distance, height, frequency, and asymmetry of the movement.
RULA / REBA Method: Postural assessment for static workstations.

The fundamental principles are: keep the back straight, bend the knees, keep the load close to the body, and avoid twisting the torso.

Regulatory Weight Limits

The Moroccan Labor Code (Law No. 65-99) sets limits for manual carrying of loads:

Women: Maximum 25 kg (reduced to 15 kg for loads carried over long distances).
Men: Maximum 55 kg (reduced to 35 kg for loads carried over long distances).
Prohibition of carrying loads exceeding 25 kg for young workers and pregnant women.

In the European Union, Directive 90/269/EEC of 29 May 1990 (manual handling of loads) requires the employer to assess risks related to manual handling and to minimize it (by using equipment, organizing work, and designing workstations). The directive does not set a specific numerical European limit: numerical limits are defined at the national level (for example, in France via the French Labor Code R4543-4 and following — limit of the load carried by a worker). The directive mandates assessment and reduction rather than a universal threshold.

Mechanical Aids

The elimination or reduction of manual carrying is achieved through the use of mechanical aids:

Hand pallet truck or electric pallet truck for moving pallets.
Hoist, overhead crane, gantry crane for heavy loads.
Lift table and scissor lift to adjust working height.
Trolleys and wheels for transporting items.

Manual Handling Training

Training in manual handling is mandatory for any exposed worker. It must be practical, tailored to the workstation, and regularly updated. It covers warm-up exercises, lifting techniques, and the use of mechanical aids.

Sources et références

Code du travail marocain (Loi n° 65-99), Titre IV (limites de port de charges) ILO NATLEX : https://natlex.ilo.org/dyn/natlex2/r/natlex/fe/details?p3_isn=67319
INRS — Manutention manuelle (portail risques professionnels) https://www.inrs.fr/risques/manutention.html
OSHA — Materials Handling and Storage https://www.osha.gov/materials-handling