CHECKPOINTS

UNDERSTANDING THE COMPLEX GIRDLE The Rationale for Using Technology to Prevent Injury By Toni-Louise Gianatti For most people, when asked how one’s feel, the word that comes to mind is “tense.” The shoulders generally will rise around the ears if any form of stress or anxiety is present in the body.

To have the head easily balance atop the and coordination for the to move Fatigue also plays a big part. The muscles spine free of gravity, the neck with supple in all directions; the spokes must work surrounding the are relatively small rotation and a freely gliding shoulder gir- simultaneously to pull evenly and with and fatigue faster than bigger muscles, dle is upper-extremity nirvana, unheard of the same amount of strength to maintain such as those of the thigh. Fatigue in- for most manual handling workers. balance and provide a smooth ride of the terrupts the connections between these To have good shoulder organization arm. A well-organized muscles (intermuscular coordination), takes a high level of awareness and pro- has this. However, it is common for one making the joint prone to injury. prioception (i.e., the perception of joint area to pull harder or less than the other, Repetition, angles, frequencies, time motion and position; Salles et al., 2015). which, if not managed, can be the begin- frames, time patterns (exposure and Properly understanding the shoulder ning of problems. recovery), push or pull pressures, cumu- and how it functions coupled with tech- To move with ease, or for the wheel lative exposures, and static elevations are nology’s ability to record and evaluate to circle freely, consistently and with factors. Evidence suggests that work done can provide an opportunity to lessen the longevity, the shoulder girdle does not with the arm elevated more than 90° is a impact on these hard-working in require a lot of strength; it requires co- higher risk. This is especially related to the workplace. ordination. The muscles, and increased time in the position (Hanvold that hold it all in place must et al., 2015). The Wheel Hub work evenly. This takes an ability to sense All of these factors must be considered To manage workplace injuries or is- when it is overdue for a rest and perform- when deciding on training or any pro- sues pertaining to the shoulder, it must ing periodic movement changes in all gram designed to help with decreasing be understood well. This is important so directions to help keep it lubricated and the risk of injury in the workplace to help that the correct adjustments, whether prevent stiffness. Most of all, it requires a to keep this complex joint healthy. Guide- environmental or personal, are made. strong positional and movement aware- lines that seek to decrease the risk of The shoulder girdle, often simply de- ness from the host so that the latter can musculoskeletal disorders (MSDs) such as scribed as the shoulder, consists of three be adhered to (Aydin et al., 2001). the NIOSH lifting equation, Washington main : collarbones, upper arm Industrial Safety and Health Act calcula- bones and shoulder blades. The shoulder Shoulders & Posture tor, rapid upper assessment or rapid girdle has greater mobility than any oth- When referring to the shoulders, we entire body assessment suggest redesign- er joint in the body. It enables arm move- often think about posture; this has a large ing workplaces to be ergonomically safe ment in all three planes. To perform any influence on shoulder function. Habitu- for workers. Although these guidelines lifting, pushing or pulling movement, it ally slouched posture might form as the have proven their efficiency theoretically, takes many elements all working togeth- result of a work pattern, emotional state, in practical application, the variability er in harmony. The shoulder contains certain sports or even initiated in child- of workers’ body types and sizes prevent muscles that not only stabilize, but also hood, imitating the posture of a caregiver. applying these guidelines through rede- move the arm. A slouched posture weakens some signing the workplace. To help understand the workings of muscles while tightening and spasming It is common to find workers with dif- this well-organized apparatus, when vi- others. Weakening of the muscles sup- ferent posture, awareness, proprioception sualizing how it functions simultaneous- porting the shoulder due to slouched levels, strength, age, race, sex, shape and ly, it helps to use the example of a wheel posture predisposes the area to problems health conditions working in the same hub, expressed by Franklin (2002). such as torn rotator cuffs and frozen place and doing the same job. Therefore, There are three main joints in the shoulder; referring back to the wheel a workplace cannot be ergonomically shoulder girdle but for the purpose of hub, this is an example of the spokes not redesigned based on a standard height this explanation, we will focus on one: pulling simultaneously (Gianatti, 2020). or size. The challenge presented by the the glenohumeral joint, and note this diversity of workers’ anthropometric as the wheel hub. The glenohumeral Evaluating Risk Factors parameters requires a method that can joint is a ball-and-socket joint where the Incorrect shoulder mechanics or help with applying health organization upper arm attaches into the shoul- faulty movement patterns resulting from guidelines. The required method should der blade. The muscles of the shoulder learned behavior, repetition, tension, be applicable, practical and efficient. girdle are arranged radically around the emotions, pain inhibition, inflexibility, Medical doctor and physiotherapist “wheel hub” of this joint. Each spoke previous injury or pain, among other Anastasia Vasina has been part of the represents a muscle. It takes a lot of effort factors can contribute to causes of injury. research and development team at Soter

assp.org JUNE 2021 PROFESSIONAL SAFETY PSJ 53 CHECKPOINTS

Understanding the mechanics of the shoulder, how it is best used to stay healthy and having technology to assist with measuring and evaluating it is game changing for manual handling workers and safety managers. Analytics conducting extensive research single action with a large arm elevation changing for manual handling workers pertaining to the shoulder and its abilities will probably cause no harm, even if and safety managers. Given the com- and limitations in the workplace based the situational assessment indicates an plexity of the shoulder, the aim is not on health organization guidelines. “Of unacceptable arm position according to to simply redesign the workplace but to course, the most practical way to decrease international standards. However, the combine this with using technology to the risk of shoulder issues occurring in duration of single events of arm elevation help realign the girdle muscles, tendons workers is to reduce the movements that is important because it reflects the static and ligaments to create a well-oiled, easy predispose the shoulder to injuries, but loading of the arm that is associated with spinning wheel hub for a lifetime. PSJ this is not a straightforward process,” Va- the prolonged muscle activation and sina explains. “It is important to investi- muscle fatigue (Hanvold et al., 2015). References gate the extent to which occupational arm Aydin, T., Yildiz, Y., Yanmis, I., Yildiz, C. & elevation, including movement character- Frequency: How Many Times? Kalyon, T.A. (2001). Shoulder proprioception: Besides the arm elevation amplitude, A comparison between the in istics such as static loading, repetition, ve- healthy and surgically repaired shoulders. locity of the movement and overexertion the frequency of arm elevation events is an important dimension characterizing Archives of Orthopaedic and Trauma Surgery, during the day impacts musculoskeletal 121(7), 422-425. https://doi.org/10.1007s0040 health and have the tools to help deter- the exposure. It is typically represented 20000245 mine this. This is where the use of tech- by health organization guidelines as Franklin, E. (2002). Relax your neck, liberate nology for both workers and management “Number of arm elevations per minute/ your shoulders: The ultimate exercise program is aimed to help solve the problem.” hour”; this is usually measured by obser- for tension relief. Elysian Editions. Using technology to evaluate the level vation assessment and captures one task. Gianatti, T.-L. (2020, Sept. 14). Understand- of exposure and to capture this informa- High frequency may indicate repetitive ing the complex shoulder girdle. Occupational movements over one task; however, this Health and Safety. tion can improve the safety of workers Hanvold, T.N., Wærsted, M., Mengshoel, in ways that reach beyond the original is a crucial measure to be captured over a given period, be it a day, a week, or even A.M., Bjertness, E. & Veiersted, K.B. (2015). methods. Metrics such as the angle of Work with prolonged arm elevation as a risk arm elevation (both in sagittal and cor- a year, and over a variation of tasks per- factor for shoulder pain: A longitudinal study onal planes) and its characteristics such formed throughout a day. among young adults. Applied Ergonomics, 47, as repetition or static, overall duration 43-51. https://doi.org/10.1016/j.apergo.2014 of the exposure during the working day, Time Patterns: Exposure & Recovery .08.019 frequency of exposure and exposure-re- Another important aspect in the con- Salles, J.I., Velasques, B., Cossich, V., Nich- covery patterns can all be determined. text of MSD risk associated with arm ele- oliche, E., Riberio, P., Amaral, M.V. & Motta, vation is the time distribution of periods G. (2015). Strength training and shoulder pro- prioception. Journal of Athletic Training, 50(3), Angle of Arm Elevation at different exposure amplitudes: Does the timeline of exposure allow sufficient 277-280. https://doi.org/10.4085/1062-6050 The amplitude of arm elevation is the time for recovery from periods with high -49.3.84 angle describing upper-arm position elevation? Svendsen, S.W., Gelineck, J., Mathiassen, in relation to the vertical line (i.e., the S.E., Bonde, J.P., Frich, L.H., Stengaard- arm elevation angle). Arm elevation can Conclusion Pedersen, K. & Egund, N. (2004). Work above shoulder level and degenerative alterations of happen in the sagittal plane (flexion- Understanding the mechanics of extension movement) or in the coronal the rotator cuff tendons: A magnetic resonance the shoulder, how it is best used to stay imaging study. Arthritis and Rheumatism, plane (abduction-adduction movement; healthy and having technology to assist Svendsen et al., 2004). 50(10), 3314-3322. https://doi.org/10.1002/ with measuring and evaluating it is game art.20495

Duration: How Long Toni-Louise Gianatti is the head of PR and content for Soter Analytics (www.soteranalytics.com), The most common duration metric is a global safety science company producing artificial-intelligence-supported wearable solutions and the total duration of increased arm eleva- training programs to improve ergonomic safety. Gianatti has more than 25 years of movement-coach- tion during the working day that shows ing experience, with a focus on using individualized biofeedback training to break faulty movement

the cumulative aspect of the exposure. A habits and reprogram body maps to reduce injury risks. IMAGES SEISA/E+/GETTY KATLEHO

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