# Pushing and pulling risk assessment: ISO 11228-2 and the Snook & Ciriello tables explained > Trolleys, pallet trucks and carts load the shoulders and the lower back in a way lifting methods do not measure. This guide explains how ISO 11228-2 assesses pushing and pulling, how to read the Snook & Ciriello tables and what the Movement Index tells you. - Type: free guide · 5 chapters - Topics: Snook & Ciriello, Manual handling, Methods - Author: Postura Ergonomics team - Published: 2026-11-10 · Updated: 2026-11-10 - Overview: https://postura.vision/resources/guides/push-pull-risk-assessment/ - Read online: https://postura.vision/resources/guides/push-pull-risk-assessment/read/ ## Why pushing and pulling need their own method A lifting method looks at a vertical load. A trolley is moved by a horizontal force, first to get it going and then to keep it moving, and that force depends on the load, the wheels, the floor and the distance. Pushing and pulling need their own measurements and their own limits. - **75%** of women find the design-goal values of the Snook & Ciriello tables acceptable (Liberty Mutual tables, adapted by T. Bernard), which makes them a conservative target for a mixed workforce. (Source: [Snook & Ciriello, Ergonomics 34(9), 1991](https://doi.org/10.1080/00140139108964855)) - **2 forces** initial, to overcome inertia, and sustained, to keep the load moving, each with its own limit. (Source: [Snook & Ciriello, Ergonomics 34(9), 1991](https://doi.org/10.1080/00140139108964855)) - **2 methods** in ISO 11228-2, a psychophysical screening and an in-depth physiological and biomechanical procedure. (Source: [ISO 11228-2, Pushing and pulling](https://www.iso.org/search.html?q=11228-2)) - **0.85** the Movement Index up to which a task is green in the three-zone reading of Method 2, which many guidelines also apply to Method 1. (Source: [ISO 11228-2, risk zones](https://www.iso.org/search.html?q=11228-2)) ## Which ISO 11228-2 method do you need? Answer up to four questions about the push or pull task. You get the method the guide recommends, with the reason behind it. 1. Is this the first assessment of the task? If yes → **Method 1**: Start with the psychophysical screening of Method 1. It is quicker and tells you whether a deeper analysis is needed. 2. Does the checklist flag many critical factors, or is the Movement Index above the limit? If yes → **Method 2**: Escalate to Method 2, which adjusts the acceptable force for the operator, the distance and the frequency. 3. Do you need a biomechanical demonstration, for example of the load on the lower back? If yes → **Method 2**: Only Method 2 includes a check of lumbar compression to set the maximum acceptable force. 4. Is the load carried by hand rather than rolled? If yes → **Snook carrying tables**: Carrying is not pushing or pulling. Use the carrying tables of Snook & Ciriello, or ISO 11228-1, instead. If none applies: If nobody pushes, pulls or carries a load, ISO 11228-2 does not apply. Check the task for lifting (NIOSH) or repetitive work (OCRA). ## Who it is for - **HSE:** HSE managers assessing trolleys, pallet trucks and carts in logistics and production areas. - **Ergonomics:** Ergonomists who need a clear path from a quick screening to a full ISO 11228-2 assessment. - **Industrial engineering:** Engineers choosing wheels, floors and routes who need to know what lowers the force. ## Contents 1. **What ISO 11228-2 covers** — The scope of the standard, initial and sustained force, and why pushing beats pulling. 2. **The Snook & Ciriello tables** — What the design values mean, the inputs you need, out-of-range cells and mixed populations. 3. **Method 1: the screening** — The four steps, measuring force with a dynamometer and computing the Movement Index. 4. **Method 2: the in-depth assessment** — Base force, the reduction for distance and frequency, lumbar compression and the three risk zones. 5. **Assessing push and pull in practice** — Weighted representative distance, the most common mistakes and how to lower the force. ## FAQ **Which standard covers pushing and pulling?** ISO 11228-2, part 2 of the ISO 11228 series on manual handling. It covers whole-body pushing and pulling by one person, with both hands, standing or walking, applying a smooth controlled force to an object in front of them. It offers two methods: a psychophysical screening based on the Snook & Ciriello tables and an in-depth physiological and biomechanical procedure. **What is the difference between initial and sustained force?** Initial force is the force needed at the start to overcome inertia and get the load moving. Sustained force is the force needed to keep it moving once it has started. The Snook & Ciriello tables give a separate acceptable value for each, so both have to be measured and compared. **What is the Movement Index in a push-pull assessment?** The Movement Index is the ratio between the force measured on the task and the acceptable force from the Snook & Ciriello tables, computed separately for initial and sustained force. Up to 1.00 the force is within the acceptable limit. In the three-zone reading recommended by many guidelines, up to 0.85 is green, above 0.85 and up to 1.00 is yellow, borderline, and above 1.00 is red. **Is pushing better than pulling?** In most situations, yes. Pushing allows a more upright posture, recruits more efficient muscle groups and gives better forward visibility. Pulling is appropriate in specific cases, such as getting over a step or holding a load back on a slope, but it brings rotated postures that overload the shoulder and the lower back. **Which limits apply to a mixed male and female workforce?** The female limits. When the people exposed to a push or pull task are both men and women, the assessment uses the female reference values because they are more conservative. Limits for one sex are used only when the exposed population is entirely of that sex. **What does OR mean in the Snook tables?** OR stands for out of range. It marks combinations of frequency and distance outside the data the tables are based on. The tables give no value for those cells, and you should not extrapolate one without a specific methodological justification. --- ## Introduction Pushing and pulling a load on wheels, such as a trolley, a pallet truck or a cart, is assessed with ISO 11228-2 and the Snook & Ciriello tables, not with lifting methods. The risk lies in a horizontal force applied by the hands and transmitted through the shoulders, trunk and legs, and it depends on things a lifting equation does not see: the wheels, the floor, the distance and how often the load is moved. This guide explains how that assessment works, from the first screening to the in-depth analysis, so you can run it, read it and use it to decide what to change. ### What the guide covers - **What ISO 11228-2 covers**, and the difference between initial and sustained force. - **The Snook & Ciriello tables**: what their values mean and how to read them without overreaching. - **Method 1**, the psychophysical screening, and the Movement Index. - **Method 2**, the in-depth physiological and biomechanical procedure, and the three risk zones. - **Practice**: measuring the forces, the distance that really counts and how to lower the risk. ### Sources The guide follows ISO 11228-2 and the psychophysical tables published by Stover Snook and Vincent Ciriello at Liberty Mutual (Ergonomics, 1991), in the adapted edition by Thomas Bernard. It explains the structure of the method and does not reproduce the table values: use the original tables for an assessment. ## 1. What ISO 11228-2 covers ISO 11228-2 covers whole-body pushing and pulling by one person, with both hands, while standing or walking, applying a smooth and controlled force to an object in front of them. Trolleys, roll containers, pallet trucks and carts are the typical cases. ### Two forces, two limits Every push or pull task involves two different forces, and each has its own limit. | Criterion | Initial force | Sustained force | | --- | --- | --- | | **What it does** | Overcomes inertia and gets the load moving | Keeps the load moving once it has started | | **When it acts** | At the start, and at every restart | Throughout the travel, at a steadier level | | **What raises it** | Load, worn or small wheels, soft or uneven floors | Load, rolling resistance, slopes | Both have to be **measured** and **compared** with their own acceptable value. A task can pass on sustained force and fail on initial force, typically when a heavy trolley is stopped and restarted many times per shift. ### What drives the risk - **The force itself**, initial and sustained. - **Frequency**: how many times per minute, hour or shift the task is repeated. - **Distance**: how far the load travels each time. - **Hand height**: where the hands apply the force. - **Posture and floor**: the trunk position, the footing and the condition of the floor. ### Pushing is usually better than pulling In most situations **pushing is preferable to pulling**. When pushing: - the posture is more upright; - the body recruits more efficient muscle groups; - the operator sees where the load is going. Pulling remains the right choice in specific cases, such as getting a load over a step or holding it back on a slope. Its cost is a **rotated posture** that overloads the shoulder and the lower back, so it should be the exception in the design of a route, not the rule. ### Where it sits in the ISO 11228 series | Task | Standard | Typical method | | --- | --- | --- | | Lifting and lowering | ISO 11228-1 | NIOSH Lifting Equation | | Carrying | ISO 11228-1 | Cumulative mass limits, or the Snook & Ciriello carrying tables | | Pushing and pulling | ISO 11228-2 | Snook & Ciriello tables | | Repetitive work of the upper limbs | ISO 11228-3 | OCRA | ## 2. The Snook & Ciriello tables The Snook & Ciriello tables give the maximum acceptable force for a push or pull task, based on how often it is done, how far the load travels and how high the hands are. They come from psychophysical studies at Liberty Mutual and are the reference behind Method 1 of ISO 11228-2. ### What the values mean The tables are **design goals**: the values are set at a load or force acceptable to **75% of women** in the adapted Liberty Mutual tables (T. Bernard). That makes them a conservative target for a broad working population before any adjustment. Separate tables exist for lifting and lowering, carrying, pushing and pulling. ### The inputs you need | Input | What to record | | --- | --- | | **Frequency** | One push or pull every so many seconds, minutes or hours | | **Distance** | How far the load travels each time | | **Hand height** | High, middle or low point of force application (about 140, 90 and 60 cm) | | **Force type** | Initial or sustained, each read separately | For each combination the tables return an acceptable **initial** force and an acceptable **sustained** force. The adapted edition uses US units (pounds, feet for distances and inches for heights), so convert carefully. ### Out of range (OR) Some cells of the tables are marked **OR, out of range**: combinations of frequency and distance that were outside the data the tables are built on. The tables give no value there, and **you should not extrapolate one** without a specific methodological justification. If your task falls in an OR cell, change the parameter you can act on, or move to Method 2. ### Adjustment factors The tables can be converted into male-only design goals or into upper design limits with **adjustment factors**. They are different for lifting, carrying, pushing and pulling, so never apply one factor across all task types. ### Mixed populations use the female limits When the people exposed to a task are **both men and women**, the assessment uses the **female** reference values, because they are more conservative. Limits for one sex apply only when the exposed population is entirely of that sex. Amendment 1 of ISO 11228-2 (2022) states this rule explicitly. ## 3. Method 1: the screening Method 1 of ISO 11228-2 is a screening: it compares the force measured on the task with the acceptable force from the Snook & Ciriello tables and expresses the result as a Movement Index. Use it first on every push or pull task. ### The four steps 1. **Survey the situation**: the load, the trolley or truck, the route, the floor, the frequency and the people who do the task. 2. **Run the qualitative checklist**: the conditions that make pushing or pulling harder, such as poor wheels, slopes, obstacles, restricted space or awkward handles. 3. **Measure the forces** with a dynamometer: the initial force at the start and the sustained force while the load is moving. 4. **Compare** each measured force with the acceptable value from the tables for the same frequency, distance and hand height. ### The Movement Index The **Movement Index (IM)** is the ratio between the measured force and the acceptable force. It is computed separately for initial force and for sustained force. **Movement Index = measured force ÷ acceptable force from the tables** An index of 1 means the task uses exactly the acceptable force. Above 1, the force exceeds what the design goal allows. ### Reading the result ISO 11228-2 uses a two-zone reading for Method 1, and many guidelines recommend the three-zone reading of Method 2 for it too. | Movement Index | Two zones | Three zones | | --- | --- | --- | | Up to 0.85 | Acceptable | Green, acceptable | | Above 0.85, up to 1.00 | Acceptable | Yellow, borderline | | Above 1.00 | Not acceptable | Red, not acceptable | The task is classified by the **higher** of the two indices, initial or sustained. ### When to escalate to Method 2 - The checklist flags **many critical factors**. - The Movement Index is **above the limit**. - You need a **biomechanical demonstration**, for example for a redesign or a dispute. ## 4. Method 2: the in-depth assessment Method 2 of ISO 11228-2 sets an acceptable force for the specific task and operator group, starting from muscular strength, reducing it for distance and frequency and checking it against the load on the lower back. ### Three components - **Base force (FB)**: the muscular force available, which depends on sex, age and the height at which the hands apply the force. - **Reduced base force (FBr)**: the base force reduced for the distance travelled and the frequency of the task. - **Lumbar check (FLs)**: a biomechanical verification of compression on the lower back, used to set the **maximum acceptable force (FMax)**. The reduced base force is computed as: **FBr = FB × [1 − m(d) − m(f)]** where **m(d)** is the multiplier for distance and **m(f)** the multiplier for frequency. As in Method 1, the calculation is done separately for initial and for sustained force. ### The three risk zones The result is read on three zones, using the ratio between the measured force and the acceptable force. | Ratio | Zone | Meaning | | --- | --- | --- | | Up to 0.85 | Green | Acceptable | | Above 0.85, up to 1.00 | Yellow | Borderline: improve when possible | | Above 1.00 | Red | Not acceptable: act | ### When Method 2 is worth it Method 2 takes more data and more expertise. It is worth it when Method 1 flags the task, when the population differs from the one behind the tables, or when you need to show, with a biomechanical argument, that a redesign brings the force within limits. ## 5. Assessing push and pull in practice In practice, the reliability of a push-pull assessment depends on three things: forces measured with a dynamometer, a distance weighted for how the task is really done and the conditions of the route on the day. ### Weight the distance, do not guess it The distance that goes into the assessment is a **weighted representative distance**: the distance travelled, weighted by how often and for how long each kind of trip happens in the shift. It is the parameter that most often decides the result, so **calculate it from the repetitions and durations**, do not estimate it by eye. ### Measure the forces properly - Measure **initial and sustained force** separately, on the real trolley, with the real load, on the real route. - Repeat the measurement and use a representative value, not the best attempt. - Note the **hand height** and the posture at which the force is applied. ### Common mistakes - Reading only the **sustained** force and missing a high initial force. - Extrapolating a value from an **OR** cell of the tables. - Using **male** limits for a mixed workforce. - Measuring on a new trolley, on a perfect floor, on a quiet day. ### How to lower the force | Lever | Effect | | --- | --- | | **Wheels**: larger, well maintained, suited to the floor | Lower initial and sustained force | | **Floor**: smooth, level, without thresholds | Lower rolling resistance | | **Route**: shorter, fewer stops and restarts | Fewer peaks of initial force | | **Load**: split, or a powered truck above a threshold | Lower force overall | | **Push, not pull**, with handles at a good height | Better posture, more efficient muscles | ### Combine methods when the task does more than push If the operator also lifts the load on and off the trolley, assess that part with NIOSH. If the station involves repetitive work of the hands, add OCRA. Each demand gets its own method. ## Your next step List the trolleys, pallet trucks and carts in one area, note how often and how far each one moves, and run Method 1 on the busiest. A dynamometer, the Snook & Ciriello tables and an afternoon are enough to know where the forces are too high. ### With Postura Postura assesses pushing and pulling with Snook & Ciriello (ISO 11228-2): you enter the forces measured with a dynamometer, the handle height, the route and how often each trolley moves. No video is needed for this part. It sits alongside OCRA, NIOSH, REBA and time and methods in the same platform. - **See it on your own footage**: [book a demo](https://calendar.google.com/calendar/u/0/appointments/schedules/AcZssZ1vaRyHk2DvHW84TDK4rpDfgwOFSYqkmYbXOn_17BZ2S8BvLTSLYXhy7wdXo_DlMxpu61AJvnxv). - **Choosing the method**: read [OCRA vs NIOSH vs REBA](/resources/guides/ocra-vs-niosh-vs-reba/). - **Lifting and repetitive work on the same station**: read [OCRA High-Precision Checklist](/resources/guides/ocra-checklist-guide/).