Core in the Kitchen: The Kinetic Chain and Knife Use

The traditional chef’s knife, celebrated for its heritage and versatility, may actually be working against the user — particularly when it comes to force efficiency, safety, and long-term strain. Most conventional knives demand a full grip, forcing users to stabilize and drive the blade entirely with their hand and wrist. This not only reduces cutting power but also isolates force in the smallest and most fatigue-prone muscle groups in the upper extremity.

In contrast, NULU’s circular design, superior force transfer geometry and centrally positioned handle allow users to generate and transfer force directly from their core and shoulders, promoting ergonomic, stable, and powerful movement. This shift isn’t just about accessibility — it’s about unlocking biomechanical potential.

The Biomechanical Problem

When the hand is forced into a full, stabilizing grip, the body’s natural kinetic chain is interrupted. In movement science, the kinetic chain refers to the sequence of body segments and joints working together to perform a task efficiently. For athletes and manual workers alike, optimal motion starts at the core and radiates outward through the shoulders and arms to the hands. By overburdening the grip, traditional knives trap energy at the periphery.

Contemporary ergonomics research now recognizes kitchen environments as critical areas requiring biomechanical optimization. A 2024 scoping review on kitchen ergonomics emphasizes that proper kinetic chain function in food preparation spaces has been understudied despite its importance for worker health and performance.

Effective knife design hinges on optimizing both force transfer geometry and blade geometry. Traditional linear knives, with their straight blades and aligned handles, transfer force in a straight line requiring inefficient sawing motions. The force transfer geometry is suboptimal for repetitive tasks, concentrating force in specific areas rather than distributing it efficiently across the blade. This uneven force distribution increases user effort and contributes to the epidemic of kitchen-related injuries.

In sports like rowing or boxing, power flows from the hips and trunk, not the fingers. Research in kinesiology and occupational therapy has shown that tasks requiring localized muscular endurance — especially fine motor control under load — are more prone to repetitive strain injuries, fatigue, and coordination loss (Armstrong et al., 1982; Keir et al., 1998). The same holds true in the kitchen.

The Epidemic of Kitchen-Related Injuries

Recent occupational health research confirms the severity of musculoskeletal problems in food service work. A 2025 study of food service kitchen workers in Ontario found that 98.1% experienced musculoskeletal discomfort, with 88.9% reporting pain at multiple anatomical locations. Similarly, a 2024 study in Ethiopia documented that kitchen work-related musculoskeletal disorders are major public health problems that deteriorate workers’ quality of life.

Updated carpal tunnel syndrome statistics reveal alarming rates in food service occupations. California workers’ compensation data shows food processing workers face 6.3 cases per 10,000 workers annually. More concerning, NIOSH investigations found that 34–42% of workers in highly repetitive food processing jobs develop carpal tunnel syndrome. Cafeteria and food service counter attendants experience rates of 66.0 per 10,000 workers — among the highest of any occupation.

Compensatory Behaviors and Their Consequences

Chefs, home cooks, and food prep professionals often compensate for poor knife ergonomics by placing a hand on the spine of the blade, abandoning the handle entirely. While this maneuver offers slightly more control, it introduces significant hand strain. The open-pinch configuration used in spine gripping stresses the thenar and hypothenar muscles and relies on friction, not leverage. Over time, this leads to increased risk for carpal tunnel syndrome, tenosynovitis, and generalized fatigue (Rempel et al., 1992).

The Age Factor: Declining Grip Strength

The problem becomes more acute with age. Research demonstrates that grip strength declines significantly with advancing years — women lose approximately 0.19 kg of grip strength per year between ages 50–67, accelerating to 0.45 kg annually thereafter. Men experience even steeper declines of 0.51–0.95 kg per year. By age 70, individuals retain only 84–85% of their age-50 grip strength, making traditional knife designs increasingly difficult to use effectively.

Moreover, users with arthritis, neurological disorders, or upper extremity injuries often find traditional knives virtually unusable. Grip strength is among the first functions to decline with age or injury, and tools that require it as a baseline are inherently exclusionary.

The NULU Solution: Geometric Innovation for Core-Engaged Cutting

NULU’s design addresses this problem by fundamentally reimagining force transfer geometry — the spatial relationship between the handle, the user’s hand, and the blade that determines how efficiently force is transferred from the user to the cutting surface. Traditional knives force users into inefficient motions with straight-line force transfer, while NULU’s alignment of the control area with the blade optimize the entire cutting equation.

Revolutionary Offset Handle Design

The key innovation lies in NULU’s handle placement, which shifts the user’s point of force application to allow complete engagement of the blade’s crescent-shaped cutting surface. This design maximizes the blade’s effectiveness by extending the usable cutting surface approximately 45 degrees beyond what traditional Ulu designs offer. Unlike the traditional aligned-handle Ulu that restricts users to half the blade, NULU’s offset geometry enables full blade engagement.

By centering the handle above an arced blade edge, NULU aligns motion with the natural curve of the shoulder and torso. The crescent blade geometry provides mechanical advantage, allowing for more efficient cutting with less effort while maintaining continuous contact with the cutting surface. The result: less force required, greater control, and dramatically reduced fatigue. This isn’t just more comfortable — it’s more powerful. The user can engage their core, apply bodyweight, and maintain a neutral wrist position throughout the cut.

Multi-Grip Flexibility Without Compromise

NULU was designed with intentional flexibility, allowing users to employ multiple grips without compromising optimized force transfer geometry. This adaptability ensures that regardless of how NULU is held, the force applied remains efficient and ergonomic. The crescent-shaped blade and offset handle work together to maintain optimal force transfer, distributing applied force evenly across the blade:

• Precision slicing and carving engaging the forward blade section

• Direct chopping maximizing the curved blade with natural downward motion

• Heavy cleaving tasks leveraging the back section through the offset handle

• Fine julienne work maintaining force transfer efficiency for intricate cuts

• Rocking cuts ensuring consistent force transfer throughout the cutting arc

• Repetitive mincing with ergonomic comfort and efficiency

The handle placement also brings superior precision capability by better aligning the handle with the precision section of the blade, giving users greater control and accuracy for delicate cutting tasks.

This design also enables bidirectional cutting. Users can execute a controlled pull motion — cutting toward themselves in a safe, fluid arc. For seated users, individuals with limited forward range, or anyone experiencing shoulder stiffness, this technique expands access while preserving power and precision.

Evidence-Based Benefits

Multiple studies in occupational ergonomics support these findings. Reducing grip force and allowing the body’s larger muscle groups to contribute results in greater task endurance, improved safety, and lower musculoskeletal strain (Putz-Anderson, 1988; Marras et al., 2000). Recent biomechanics research confirms that compromised biomechanical control during activities affects performance, particularly in tasks requiring landing and force transfer.

User feedback from NULU adopters supports these biomechanical principles. Users report reduced fatigue during extended food preparation, improved cutting control, and decreased hand strain compared to traditional knife designs. These observations align with the predicted benefits of core-engaged cutting mechanics.

Universal Design, Universal Benefit

Inclusion is often viewed as a trade-off — making a tool easier to use for some at the cost of performance for others. NULU defies that assumption. By embracing the physics of circular cutting and optimizing for force transfer from the core, it offers a universal benefit: better, safer, more sustainable cutting for all.

NULU offers this advantage not just to people with disabilities or chronic pain, but to chefs, caregivers, seniors, and anyone seeking more efficient motion in the kitchen. With 2024 research showing that food service workers with jobs involving cooking and food preparation are at higher risk of sustaining workplace injuries or musculoskeletal symptoms, innovative ergonomic solutions like NULU become essential tools for injury prevention.

References

Armstrong, T.J., Foulke, J.A., Joseph, B.S., & Goldstein, S.A. (1993). Investigation of cumulative trauma disorders in a poultry processing plant. American Industrial Hygiene Association Journal.

Keir, P.J., Bach, J.M., Rempel, D.M. (1998). Effects of computer mouse design and task on carpal tunnel pressure. Ergonomics, 41(8), 1080–1094.

Rana, R., Thomas, D., & El-Farargy, N. (2024). Kitchen ergonomics in health and healthcare: A rapid scoping review. Health & Place, 82, 103986. https://doi.org/10.1016/j.healthplace.2023.103986

Katz, D. & Lou, G. (2024). Maximizing Efficiency and Ergonomics Through Optimized Force Transfer Geometry in Knife Design. Unpublished internal data, NULU Research.

Marras, W.S., Davis, K.G., Kirking, B.C., & Bertsche, P.K. (2000). A comprehensive analysis of low-back disorder risk and spinal loading during the transferring and repositioning of patients using different techniques. Ergonomics, 42(7), 904–926.

Prevalence of musculoskeletal discomfort, occupational working factors, and work demands amongst food service kitchen workers in Ontario Canada. (2025). Discover Public Health.

Putz-Anderson, V. (1988). Cumulative Trauma Disorders: A Manual for Musculoskeletal Diseases of the Upper Limbs. Taylor & Francis.

Rates of Carpal Tunnel Syndrome in a State Workers’ Compensation Database. (2018). CDC MMWR.

Rempel, D., Gerr, F., & Goldner, G. (1992). The effect of workplace design on hand and wrist biomechanics. Journal of Hand Surgery, 17(5), 861–870.

Work-related musculoskeletal disorders among kitchen workers in hospitality industry. (2024). Ethiopia Public Health Journal.