Ergonomic assessment of veterinarians during performance of bovine reproductive examinations

Robyn M. Reist Canadian Centre for Health and Safety in Agriculture, University of Saskatchewan, Saskatoon, SK S7N 2Z4 Canada.

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Brenna L. Bath Canadian Centre for Health and Safety in Agriculture, University of Saskatchewan, Saskatoon, SK S7N 2Z4 Canada.
School of Rehabilitation Science, College of Medicine, University of Saskatchewan, Saskatoon, SK S7N 2Z4 Canada.

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Murray D. Jelinski Department of Veterinary Medicine, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, SK S7N 2Z4 Canada.

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Nathan E. N. Erickson Department of Veterinary Medicine, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, SK S7N 2Z4 Canada.

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Chris R. Clark Department of Veterinary Medicine, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, SK S7N 2Z4 Canada.

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Catherine M. Trask Canadian Centre for Health and Safety in Agriculture, University of Saskatchewan, Saskatoon, SK S7N 2Z4 Canada.
Division of Ergonomics, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, Stockholm, Sweden.

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Abstract

OBJECTIVE

To identify and quantify potential ergonomic hazards associated with routine reproductive examinations of cattle.

SAMPLE

7 bovine veterinarians.

PROCEDURES

Each veterinarian was observed and videotaped during 2 bovine reproductive examination appointments. During each appointment, a force-matching protocol was used to estimate the entry force used by the veterinarian to insert an arm into a cow's rectum. Veterinarian posture and repetitive movements and the work environment were assessed and quantified during review of the video recordings. Descriptive data were generated.

RESULTS

Of the 14 appointments observed, 9 and 5 involved examination of beef and dairy cows, respectively. For all veterinarians, an arm inclination ≥ 60° was observed during most reproductive examinations. The number of examinations performed per hour ranged from 19.1 to 116.8. The estimated entry force ranged from 121 to 349 N. During all 9 appointments involving beef cows, the veterinarian participated in other tasks (eg, operating overhead levers, opening gates, or assisting with cattle handling) that represented ergonomic hazards.

CONCLUSIONS AND CLINICAL RELEVANCE

Results confirmed that reproductive examination of cattle exposes veterinarians to various ergonomic hazards involving awkward positions and repetitive and forceful exertions that can contribute to musculoskeletal discomfort and injury, particularly of the upper extremities (neck, shoulders, upper back, arms, elbows, wrists, and hands). Veterinarians frequently participated in other tasks during reproductive examination appointments that exposed them to additional ergonomic hazards. Risk mitigation strategies should prioritize minimizing exposure of veterinarians to tasks not directly associated with the reproductive examination procedure to decrease their overall ergonomic hazard burden.

Abstract

OBJECTIVE

To identify and quantify potential ergonomic hazards associated with routine reproductive examinations of cattle.

SAMPLE

7 bovine veterinarians.

PROCEDURES

Each veterinarian was observed and videotaped during 2 bovine reproductive examination appointments. During each appointment, a force-matching protocol was used to estimate the entry force used by the veterinarian to insert an arm into a cow's rectum. Veterinarian posture and repetitive movements and the work environment were assessed and quantified during review of the video recordings. Descriptive data were generated.

RESULTS

Of the 14 appointments observed, 9 and 5 involved examination of beef and dairy cows, respectively. For all veterinarians, an arm inclination ≥ 60° was observed during most reproductive examinations. The number of examinations performed per hour ranged from 19.1 to 116.8. The estimated entry force ranged from 121 to 349 N. During all 9 appointments involving beef cows, the veterinarian participated in other tasks (eg, operating overhead levers, opening gates, or assisting with cattle handling) that represented ergonomic hazards.

CONCLUSIONS AND CLINICAL RELEVANCE

Results confirmed that reproductive examination of cattle exposes veterinarians to various ergonomic hazards involving awkward positions and repetitive and forceful exertions that can contribute to musculoskeletal discomfort and injury, particularly of the upper extremities (neck, shoulders, upper back, arms, elbows, wrists, and hands). Veterinarians frequently participated in other tasks during reproductive examination appointments that exposed them to additional ergonomic hazards. Risk mitigation strategies should prioritize minimizing exposure of veterinarians to tasks not directly associated with the reproductive examination procedure to decrease their overall ergonomic hazard burden.

Introduction

Musculoskeletal discomfort of large animal veterinarians and its potential predictors have been investigated in various countries, with a high prevalence of MSKD consistently reported in the upper extremities (defined as neck, shoulders, upper back, arms, elbows, wrists, and hands) of that population.1,2,3,4 It has long been hypothesized that reproductive examinations of cattle are a major contributor to MSKD for bovine veterinarians.5,6,7 In cows, examination of the reproductive tract involves the insertion of the veterinarian's arm (ie, manual palpation of the reproductive tract per rectum [rectal palpation]) or a UEW into the rectum of the animal. Rectal palpation of cattle cannot be completely replaced by technology, although in beef cattle practice, a UEW can often be used for most reproductive examinations, with rectal palpation necessary for pregnancy confirmation only occasionally.

Epidemiological studies that have attempted to model the association between MSKD of veterinarians and reproductive examination of cattle have yielded mixed results. Most of those studies2,3,6,7,8 have had a cross-sectional design, which cannot establish cause-and-effect relationships. Additionally, many studies2,3,6,7,8 involved the use of self-reported data, and there was a lack of consistency across studies in regard to the metrics used to quantify symptoms of MSKD and the total exposure burden of reproductive examinations. Further complicating the issue is that reproductive examination of cattle may be seasonal depending on the type of cattle. Reproductive examination of dairy cattle generally occurs throughout the year, whereas reproductive examination of beef cattle generally occurs only in the fall and often involves the use of a UEW.4

Despite the lack of consistent evidence, veterinarians perceive reproductive examination of cattle to be one of the primary job-related tasks that contribute to MSKD of the upper extremities.2,9,10 In western Canada, bovine veterinarians rated reproductive examination of cattle as the second most physically demanding task they perform.4 In a large survey11 of New Zealand veterinarians from all types of practices (small, large, and mixed animal), rectal palpation of large animals emerged as the top perceived cause of MSKD. In a 1996 survey6 of members of the American Association of Bovine Practitioners, 132 of 432 (31%) respondents reported experiencing MSKD that they attributed to rectal palpation of cattle. Results of a rapid upper limb assessment of bovine reproductive examinations indicate that, aside from the risk of acute injury associated with working in close proximity to an unpredictable large animal, the procedure is also associated with repetitive forceful movements and the assumption of awkward postures by the individual performing it, regardless of whether it is performed manually or with a UEW, even under optimal conditions.12 Results of large-scale systematic reviews13,14 indicate that workplace exposure to repetitive forceful or heavy physical work and awkward (non-neutral) postures is associated with MSKD of the upper extremities and lower back.

To our knowledge, the aforementioned rapid upper limb assessment of bovine reproductive examination12 is the only ergonomic assessment of the procedure in the published literature. In 1996, Dr. Ronald Ailsby, a Canadian orthopedic surgeon who had treated a number of bovine veterinarians with shoulder and neck pain, published a report5 that described the syndrome and summarized the results of a survey of large animal veterinarians he conducted to further characterize the syndrome and its potential relationship with rectal palpation. In that report,5 he hypothesized a potential pathogenic mechanism and prevention strategies for the syndrome. However, that assessment5 was made on the basis of assumed pathological lesions and is not particularly useful for ergonomics practitioners or at-risk asymptomatic individuals who want to prevent injuries from occurring. The objective of the study reported here was to identify and quantify potential ergonomic hazards (eg, posture, repetition, force, and workplace environment) associated with routine reproductive examinations of cattle to help inform the prioritization and development of risk mitigation strategies.

Materials and Methods

Participants

The study was reviewed and approved by the University of Saskatchewan Behavioral Ethics Board. An email describing the study with an invitation for study participation was sent to members of the WCABP who resided within a 60-mile radius of the University of Saskatchewan by WCABP administrative staff in the summer of 2018. Two follow-up emails were sent in September and November 2018, the latter of which expanded the recruitment pool to the entire province of Saskatchewan. Additionally, a snowball sampling method was used to access the professional networks of study personnel who were also veterinarians and to directly contact potential study participants. Seven veterinarians agreed and provided written informed consent to participate in the study. Three of those 7 veterinarians were recruited through the WCABP emails, and the remainder were recruited by direct invitation.

Study personnel accompanied each participant on 2 appointments, during which routine reproductive examinations (examinations) of cattle were performed between October 2018 and January 2019. Examinations were performed by rectal palpation or use of a UEW (Figure 1), and the type of cattle (dairy or beef) differed among appointments. Participants also completed a survey regarding personal and workplace characteristics, current and past MSKD symptoms, and perceptions of physically demanding tasks as described in a previous study4 of MSKD among Canadian veterinarians.

Figure 1
Figure 1

Representative photographs of reproductive examinations being performed on cattle by manual palpation and ultrasonographic examination of the reproductive tract per rectum (rectal palpation; A) and use of a UEW (B).

Citation: Journal of the American Veterinary Medical Association 258, 11; 10.2460/javma.258.11.1243

Video observation and data collection

Study personnel video recorded each appointment. The video of each appointment was subsequently reviewed and analyzed to determine the repetition and frequency of examinations, veterinarian posture and extent of physical activity during the examinations, and work environment.

The repetition and frequency of examinations were assessed by quantifying the number of examinations performed during each appointment, duration of each examination (in seconds), and duration between each examination (in seconds). From those values, the median examination time, median rest time, and percentage of observed time spent performing examinations were calculated. The percentage of each appointment that the participant spent performing examinations was calculated as the time spent performing examinations divided by the duration of the observation.

The posture and physical activity of participants were assessed by observation in real time and during review of the video recorded appointments. Participants were monitored for extreme postures (ie, arm inclinations of ≥ 60° and ≥ 90°). Arm inclination was defined as the angle at which the arm was elevated above neutral in any plane of movement; neutral arm angle is hanging relaxed at the side of an individual standing upright (Figure 2). An arm inclination of ≥ 90° was considered present when the participant was required to operate an overhead lever or pulley system to open a gate between cows. For each participant, the condition extreme arm inclination angle was recorded as present if that angle was observed during most of the examinations. Other routine physical activities (eg, cattle handling and operation of cattle restraint facilities) that exposed the participant to awkward postures were also recorded.

Figure 2
Figure 2

Schematic depictions of arm inclination, which was used to assess veterinarians for extreme posture when performing reproductive examinations of cattle. Arm inclination was defined as elevation of the arm from a neutral position (arm hanging relaxed by the side of an upright individual; red line) in any plane. Arm inclination angles ≥ 60° and ≥ 90° were considered extreme postures for the veterinarians of this study.

Citation: Journal of the American Veterinary Medical Association 258, 11; 10.2460/javma.258.11.1243

For each appointment, the work environment was assessed for additional ergonomic hazards to which the participant was exposed while conducting examinations and associated activities. Factors assessed included whether the examination was performed by rectal palpation or use of a UEW, type of cattle restraint system used (chute, head locks, or palpation rail), and cattle temperament. An aggregate cattle agitation score was assigned to each appointment to characterize the typical temperament of the animals examined. The aggregate agitation score could range from 1 to 3 and was a modification of the 5-point temperament score described by Grandin15 (Grandin temperament scale). Briefly, an agitated cow was defined as an animal that subjected the veterinarian to sudden, forceful movements when being examined. An aggregate agitation score of 1 indicated that most of the cattle examined during the appointment were not agitated (ie, most cows would score a 1 or 2 on the Grandin temperament scale). An aggregate agitation score of 2 indicated that approximately half of the cows were agitated (ie, approx half of the cows would score a 3 on the Grandin temperament scale), whereas an aggregate agitation score of 3 indicated that most cows appeared agitated (ie, most cows would score a 4 or 5 on the Grandin temperament scale).

Estimation of entry force

Because it was not practical to directly measure the force used by a participant to insert their arm or the UEW through the anal sphincter and into the rectum, a force-matching estimation protocol was used. This protocol was adapted from a protocol described by Bao and Silverstein16 to accommodate a flat-palm posture. Briefly, during each appointment, a convenience sample of 10 cows was selected. The distance between the flooring surface and anus was measured for each of those cows, and the mean of those measurements was calculated to estimate the mean anus height for the cattle examined during that appointment. A handheld dynamometera was mounted on a static vertical surface at the mean anus height. The participant assumed a posture similar to that used during reproductive examination of cattle and, with their predominant palpation arm, pushed against the dynamometer with the subjective mean force they typically used to enter the rectum. This process was repeated 5 times for each appointment, and the estimated mean entry force was calculated for each appointment.

Data analysis

Descriptive data were generated. Because of the small number of study participants (n = 7), inferential tests were not performed.

Results

Participants

Seven veterinarians completed the study. The study participants included 2 women and 5 men ranging in age from 30 to 66 years (Table 1). The number of years of experience for the participants ranged from 5 to 41, and the estimated number of reproductive examinations performed each year ranged from 2,000 to 16,000. Five of the 7 participants reported that they had experienced upper extremity MSKD within the 12 months prior to study enrollment; however, MSKD had not interfered with their work. One participant reported he had not experienced upper extremity MSKD within the 12 months prior to study enrollment, and the remaining participant declined to answer that question.

Table 1

Demographic characteristics for 7 veterinarians who underwent ergonomic assessment while performing reproductive examinations of cattle.

Participant Gender Age (y) No. of years of experience Height (cm) Percentage of practice time devoted to cattle* No. of reproductive examinations performed/y* Upper extremity MSKD within the 12 months prior to study enrollment
1 Woman 30 5 163 65 3,000 Yes
2 Man 37 10 178 45 7,000 Yes
3 Man 34 9 178 80 16,000 Yes
4 Man 60 32 169 95 10,000 No
5 Man 47 22 175 60 11,000 Yes
6 Woman 37 13 173 45 6,000 Yes
7 Man 66 41 185 75 2,000 Declined to answer

Self-reported estimate.

Upper extremity MSKD was defined as discomfort associated with the neck, shoulders, upper back, arms, elbows, wrists, or hands.

Repetition and frequency of examinations

The duration of the appointments ranged from just less than 1 hour to a little over 3.5 hours (Table 2). The number of examinations performed per hour ranged from 19.1 to 116.8. The median examination time ranged from 5 to 80 seconds, and 3 veterinarians succeeded in examining > 100 cows/h during an appointment. The median rest time between cows ranged from 6 to 50 seconds. Within each appointment, the distribution for rest time between cows was highly skewed because several factors led to sporadic extended rest periods, such as traveling to another barn, moving groups of cows from secondary holding pens to the examination facility (chute), or waiting for other farm tasks (eg, milking) to be completed. Therefore, mean rest time between cows was not an appropriate metric for this study.

Table 2

Summary statistics for each of the 2 observed appointments for the veterinarians described in Table 1.

Participant Appointment Duration of appointment (h:min:s) No. of examinations performed No. of examinations/h Median (range) examination time/cow (s) Median (range) rest time between cows (s) Percentage of appointment spent performing examinations Mean (SD) estimated entry force (N)
1 1 3:39:19 156 42.7 25 (2–77) 6 (1–976) 31 121 (19.5)
2 1:32:41 79 51.0 37 (13–100) 24 (2–124) 57 183 (13.3)
2 1 1:06:14 77 70.0 20 (7–117) 13 (3–312) 43 232 (23.7)
2 1:47:47 59 32.8 30 (7–57) 50 (2–879) 33 326 (61.1)
3 1 2:44:13 154 56.3 7 (3–35) 38 (1–221) 13 141 (31.6)
2 1:58:02 207 105.3 9 (4–20) 18 (1–142) 31 242 (19.4)
4 1 2:28:20 47 19.1 80 (18–297) 46 (8–710) 48 157 (20.1)
2 1:05:00 100 92.3 9 (3–79) 22 (1–98) 38 153 (17.3)
5 1 0:56:44 96 101.1 11 (4–19) 16 (15–149) 42 349 (71.0)
2 2:07:34 156 73.1 8 (5–64) 35 (10–75) 19 242 (95.4)
6 1 3:11:40 173 54.1 10 (2–70) 26 (1–94) 18 203 (77.1)
2 2:31:12 294 116.8 5 (3–54) 18 (1–68) 25 140 (10.41)
7 1 3:13:00 143 44.5 12 (3–79) 41 (1–289) 19 157 (73.3)
2 2:10:18 133 61.4 10 (1–71) 26 (1–994) 24 199 (31.8)

Veterinarian posture and physical activity

An arm inclination of ≥ 60° during most examinations was recorded for all 7 participants (Table 3). An extreme arm inclination of ≥ 90° was recorded for only 2 participants and was associated with maneuvering an overhead lever to operate an access or head gate on a chute between each cow. Participant 6 operated an overhead pulley system between cows during appointment 2, but this movement was not visible on the video recording, so an extreme arm inclination in association with that task could not be verified.

Table 3

Reproductive examination characteristics and postures observed for the veterinarians described in Table 1 during each of the 2 observed appointments for those veterinarians described in Table 2.

Participant Appointment Examination method Cattle type Aggregate agitation score* Extreme postures observed Restraint facilities Other activities
1 1 Rectal palpation Dairy 1 Right arm ≥ 60° Palpation rail; manual chute None
2 Rectal palpation Dairy 1 Right arm ≥ 60° Head locks; hydraulic chute None
2 1 Rectal palpation Dairy 2 Left and right arms ≥ 60° Head locks; hydraulic chute Operated overhead levers on hydraulic chute
2 Rectal palpation Dairy 1 Left arm ≥ 60° Head locks None
3 1 UEW Beef 2 Left arm ≥ 90° Right arm ≥ 60° Manual chute Operated access gate via overhead lever and assisted with cattle handling
2 UEW Beef 1 Right arm approx 60° Chute with hydraulic head gate and manual squeeze feature Opened access gate and assisted with cattle handling
4 1 Rectal palpation Dairy 1 Left arm ≥ 60° Tie stalls; pens None
2 UEW Beef 1 Left arm ≥ 60° Manual chute Opened access gate and cattle door and assisted with cattle handling
5 1 Rectal palpation Beef 3 Left and right arms ≥ 60° Manual chute Opened access gate and positioned butt bar
2 Rectal palpation Beef 3 Left arm ≥ 60° Manual chute Opened access gate and assisted with cattle handling
6 1 UEW Beef 3 Left arm ≥ 60° Right arm ≥ 90° Manual chute Opened access gate operated overhead lever on chute, and assisted with cattle handling
2 UEW Beef 1 Left and right arms ≥ 60° Hydraulic chute Opened access gate via overhead pulley and assisted with cattle handling
7 1 Rectal palpation Beef 2 Left and right arms ≥ 60° Manual chute Opened cattle and access gates and assisted with cattle handling
2 Rectal palpation Beef 2 Left and right arms ≥ 60° Manual chute Opened access gate, positioned butt bar and assisted with cattle handling

Rectal palpation was defined as manual palpation of the reproductive tract per rectum. Extreme postures were defined as arm inclinations of ≥ 60° and ≥ 90°. Arm inclination was defined as the angle at which the arm was elevated above neutral (ie, arm relaxed and not elevated in an upright individual), regardless of plane. An extreme posture was considered present only when it was observed during most examinations. A manual chute was defined as a cattle chute with a manually operated head gate and squeeze option (mechanical feature of the chute that was used to apply pressure to the sides of the animal to help minimize its side-to-side movement). A hydraulic chute was defined as a cattle chute with a hydraulically operated head gate and squeeze option. A butt bar was a fence post (or something similar), which was slid through the chute behind the animal to prevent it from backing up into the veterinarian during the examination.

The aggregate agitation score could range from 1–3, where 1 indicated that most cattle examined were not agitated (ie, cows did not subject the veterinarian to sudden, forceful movements when being examined), 2 indicated that approximately half the cows examined were agitated (ie, cows subjected the veterinarian to sudden, forceful movements when being examined), and 3 indicated that most cows were agitated.

Work environment

Observed environmental factors and other potentially hazardous activities from an ergonomic perspective that were not directly associated with the reproductive examinations were summarized (Table 3). During examination, most beef cattle were restrained in a chute with a manually operated head gate and squeeze option (mechanical feature of the chute that was used to apply pressure to the sides of the animal to help minimize its side-to-side movement), whereas most dairy cows were restrained in head locks (Figure 3). During 1 appointment, dairy cows were examined while they were restrained in a palpation rail, in which cows were squeezed together to limit their movement during examination. Most dairy operations also had cattle chutes similar to those used on beef operations, which were occasionally used to examine cows with special needs or when the number of cows to be examined was insufficient for them to be adequately restrained for examination in head locks or a palpation rail. At 1 dairy operation, cows were examined while restrained in tie stalls, which limited their movement. At another operation, a group of dairy heifers was examined in a pen; each heifer was herded into a corner of the pen and squeezed between the fence and a swinging gate to restrain it during examination. In general, dairy cattle were less agitated than beef cattle during examination. During 7 (1 dairy and 6 beef) of the 14 observed appointments, participants were regularly subjected to unpredictable forceful movement from cattle that we characterized as being agitated. During all 9 appointments involving beef cattle, participants were observed doing other activities that posed potential ergonomic risks, such as operating overhead levers or pulleys and assisting with cattle handling, which typically involved physically pushing on a cow's backside or twisting a cow's tail to encourage it to move forward.

Figure 3
Figure 3

Representative photographs of commonly used methods to restrain cattle during reproductive examinations. A—Photograph of a manually operated cattle chute. To load the cow into the chute, the access (personnel) gate is closed and latched so the animal cannot escape out the side of the chute, and the head gate is opened. The cattle gate is opened to allow the cow to enter the chute, and the head gate is closed as the cow's head passes through it, preventing the animal from exiting the chute. The cattle gate is closed to prevent other cattle from entering the chute. This chute is equipped with a squeeze option, which is a mechanical feature that allows the sides of the chute to be drawn together to apply pressure on the sides of the animal to help calm it and prevent excessive side-to-side movement during examination. Once the animal is adequately restrained, the access gate is opened so the veterinarian can enter the chute behind the animal and perform the examination. B—Photograph depicting dairy cattle restrained in head locks for reproductive examination. Head locks are a series of connected stanchions that are generally permanently mounted along a feed alley. Cows must put their heads through the head locks to access feed. The stanchions can be set in a lock position to prevent cows from backing up and restraining them when necessary. When most of the head locks are occupied, side-to-side movement of the animals is minimized, and a veterinarian can perform reproductive examinations on a large group of cows in a fairly safe and efficient manner. C—Photograph depicting dairy cattle restrained in a palpation rail for reproductive examination. Cows are lined up immediately next to one another inside a palpation enclosure (approx 1.5 × 5 m). Cows are restrained by being crowded in and pressed against one another; a rope is tied behind the last cow to prevent the row of cows from exiting or moving laterally. The veterinarian performs reproductive examinations by reaching through the rails on the back side of the palpation enclosure.

Citation: Journal of the American Veterinary Medical Association 258, 11; 10.2460/javma.258.11.1243

Entry force

The median for the estimated mean entry force used by participants during examinations was 191 N (range, 121 to 326 N; Table 2). The estimated mean entry force exceeded 300 N during only 2 of the 14 observed appointments.

Discussion

To our knowledge the present study was the first to describe ergonomic assessment of multiple veterinarians while they were performing reproductive examinations of cattle in various types of work environments. Results of this study confirmed anecdotal reports that reproductive examination of cattle can expose veterinarians to various ergonomic hazards including awkward posture and repetitive and forceful exertions. The present study also revealed that it is common for veterinarians to participate in other tasks during reproductive examination appointments that pose a risk for additional exposure to ergonomic hazards.

Given that the present study was the first in which ergonomic assessment of veterinarians was performed while they were performing reproductive examinations of cattle, we cannot directly compare the findings of this study with results of other similar studies. However, the results of the ergonomic assessments for the veterinarians of the present study were similar to those for other workers who perform tasks involving the arms and shoulders. Airport baggage handlers are frequently exposed to awkward postures and repetitive heavy lifting, and that population has a high incidence of back and shoulder injuries.17 However, luggage is stationary and ultimately controlled by the baggage handler, whereas cattle are less predictable. House painters also spend a proportionately large amount of time working with elevated arms and have a high incidence of shoulder MSKD.18 Although house painting requires less force than is necessary for insertion of an arm or UEW into a cow's rectum, repetitive motion of the arm above shoulder level puts house painters at risk for shoulder injuries and abnormal muscle fatigue.19 Results of a large cross-sectional study20 of male machinists, car mechanics, and house painters indicate that working with arms in an extremely elevated position (> 90°) has a direct dose-dependent relationship with all symptoms of shoulder discomfort (eg, general pain, pain with disability, and supraspinatus tendinitis) evaluated.

When performing reproductive examinations of cattle, all veterinarians assessed in the present study assumed awkward positions in which arm inclination was at least 60°. It was typical for veterinarians to elevate their arm at least 60° to access a cow's rectum, regardless of whether they were inserting their arm or a UEW into the rectum. Awkward shoulder postures were also observed during secondary tasks performed by the veterinarians, particularly during appointments involving beef cattle (beef appointments). During 3 beef appointments, veterinarians were required to reach overhead levers or pulley systems to operate the cattle chute and facilitate cattle movement. This necessitated the assumption of arm inclinations > 150° between examinations. During all beef appointments, the veterinarian was responsible for operating the access gate to the cattle chute between examinations. The latching mechanism of the access gate differed among the chutes, and some veterinarians remarked that the continual opening and closing of the access gate caused MSKD in the lower portion of the arm and wrist.

Repetition is an obvious risk factor for upper-extremity MSKD in association with reproductive examinations of cattle. In the present study, the median examination rate was 58.9 examinations/h (range, 19.1 to 116.8 examinations/h), and the examination rate was > 100 examinations/h during 3 of the 14 observed appointments. In other studies2,6 involving bovine veterinarians, the mean rectal palpation rate was 136 and 250 cows/d. In cattle practice, high reproductive examination rates are generally not sustained throughout the year. Instead, the reproductive examination workload, particularly in beef practice, tends to be seasonal, with several days of rest between days during which high numbers of reproductive examinations are performed. In the present study, the median examination time exceeded the median rest time for 4 of the 5 appointments involving dairy cattle (dairy appointments). Repetitive secondary ergonomic hazards, such as operating overhead levers on chutes, were also observed in the present study. During each of the 9 beef appointments observed in the present study, the veterinarian opened at least 1 gate between examinations, which may have contributed to the overall burden on the musculoskeletal system and hastened fatigue. Positive associations between repetitive work and symptoms of shoulder discomfort have been described.13 However, in a 2010 systematic review14 of longitudinal studies, repetitive movement was not identified as a risk factor for shoulder MSKD but was a risk factor for MSKD of the elbow joint and forearm, and pain in the elbow joint and forearm can be a symptom of shoulder injury.21

In the epidemiological literature, forceful or heavy physical work, such as pushing, is positively associated with low back MSKD13,14 and may increase the risk of shoulder MSKD.14,22 Although the entry force exerted by veterinarians during reproductive examination of cattle was not directly measured in the present study, the mean estimated entry force was fairly consistent among appointments, ranging between 120 and 250 N for all but 2 appointments. We were not surprised by the large variation in estimated entry force observed among and within veterinarians because, from a biomechanical perspective, within-subject variability is common during repetition of identical physical exertions.23,24 Additionally, each appointment posed unique situations for the veterinarians, such as the size and temperament of cows, fecal volume and consistency within the rectum, and restraint facilities, which likely also contributed to variability in the estimated entry force. The existing literature22,25 on the ergonomic effects of pushing generally involves evaluation of a 2-handed push, with the assumption that the object being pushed is a cart or transfer device. Although tasks limited to 1-handed pushes are not common, the Canadian Centre for Occupational Safety and Health has established a recommended force limit of 110 N for a 1-handed push performed with the arm elevated to shoulder height.26 The type of forceful exertion required for an individual to insert their arm or UEW into a cow's rectum is unique to that task and requires further biomechanical analysis. Surprisingly, in the present study, the estimated mean entry force did not differ substantially between rectal palpation and UEW placement, although it was clear that the force exerted by the cow on the veterinarian was greatly reduced when the veterinarian did not have to insert their arm into the cow.

While performing reproductive examinations of cattle, veterinarians are exposed to all of the ergonomic hazards identified in previous studies18,19,20 that focused on posture and repetition of tasks by house painters and car mechanics as well as forceful exertions associated with the often unpredictable movement of the cow. Thus, veterinarians are at an increased risk for musculoskeletal injuries of the upper extremities when performing reproductive examinations of cattle.

The present study confirmed that reproductive examination of cattle exposes veterinarians to repetitive awkward postures and forceful exertions, as expected. However, we were surprised to find that secondary tasks, such as gate and cattle handling, also presented prominent posture and repetition hazards for veterinarians. Hazards associated with secondary tasks were more consistently observed during beef appointments than during dairy appointments, likely because reproductive examination of cows typically occurs only once per year on beef farms, whereas the task is performed frequently throughout the year on dairy farms. Consequently, the handling facilities for reproductive examination of cows are often of lower quality on beef farms than dairy farms owing to the infrequency of use, and bovine veterinarians may be exposed to ergonomic hazards associated with secondary tasks associated with reproductive examination of cattle on an almost daily basis during the fall when beef cattle are typically examined for pregnancy. In the present study, we observed that larger livestock operations tended to have higher quality and often automated (ie, hydraulic chutes) cattle handling facilities than did smaller operations, which alleviated some of the repetitive strain on the person responsible for operating the head gate and squeeze for cattle restraint. However, for the 2 operations with hydraulic chutes observed during the present study, the access gate of the chutes, which was operated by the veterinarian, had manually operated latch mechanisms.

Cattle handling techniques appeared to affect the agitation level of the cows. Subjectively, cows were more likely to make unexpected movements as their state of agitation increased, which increased the risk of traumatic injury to the veterinarian during the reproductive examination procedure. For example, frequent use of an electric prod while a cow was being loaded into the chute typically caused the animal to become agitated and continue to struggle even after being restrained by the head gate and squeeze feature. Loading of cows into the chute without the use of electric prods or otherwise aggressive handling practices (paddles or yelling) generally led to the cows being fairly calm and moving less during examination. When examining agitated cows, veterinarians generally had to use more forceful exertion to insert their arm or the UEW into the rectum, compared with the exertion required to insert their arm or the UEW into the rectum of cows that were not agitated, owing to the animal struggling against the procedure. That observation was consistent with findings of another study27 in which the adoption of low-stress cattle handling techniques (ie, eliminating the use of dogs, electric prods, and excessive human-induced agitation) resulted in a safer work environment for both animals and people.

The present study had several limitations inherent in any exploratory study. Only 7 veterinarians were observed, and the working conditions varied greatly among the observed appointments within and among veterinarians. Thus, statistical comparisons between the veterinarians of this study or larger population-based studies were not feasible. The lack of direct measurement of posture and forces (eg, entry forces) exerted by the veterinarians during the reproductive examinations prevented quantification of those variables and calculation of biomechanical strain. Research into hand force–matching estimates has traditionally focused on grip force,16,28 and an attempt to validate that methodology yielded mixed results, owing to intersubject variability.29 Forces exerted by veterinarians and to which veterinarians are exposed during reproductive examination of cattle may need to be measured by simulation in a laboratory setting. The mean estimated entry force calculated for the veterinarians of the present study was a simulated measure of the peak push force used by the veterinarian to insert their arm into a cow's rectum; it did not account for the various other forces to which veterinarians are exposed during reproductive examinations of cattle. Additionally, we were unable to measure or estimate the force exerted on veterinarians by cow movements, and it is possible that force might be greater than the estimated entry force. Despite the exploratory nature and associated limitations of the present study, the findings can be used to inform and prioritize strategies to prevent upper extremity MSKD in veterinarians resulting from reproductive examination of cattle.

Unfortunately, the observations of the present study failed to provide definitive evidence regarding which aspect of reproductive examination of cattle was the main contributor to shoulder injuries in veterinarians. It is likely that a combination of the observed hazards along with individual psychosocial risk factors, such as stress owing to long hours of work and physical activities of daily life (eg, farming, childcare, and athletic activities), all contribute to upper extremity MSKD in bovine veterinarians. Awkward posture, repetition, and forceful exertions are inherent characteristics of reproductive examination of cattle. Agitated cattle also increase the potential for veterinarians to incur acute injuries. However, there are ways these risks can be minimized, and there is an opportunity for veterinarians and cattle producers to work together to prioritize risk mitigation strategies, ideally by following a hierarchy-of-controls approach (ie, elimination, substitution, engineering, administrative, and protective equipment).30

Although elimination and substitution are often difficult controls to implement, there are a number of potential strategies to eliminate or reduce secondary exposure of veterinarians to ergonomic hazards that are not extensive or expensive and that could be implemented immediately. This may be as simple as having a farm employee be responsible for opening gates rather than the veterinarians, changing a stiff gate latch for a less physically demanding mechanism, or adopting low-stress cattle handling practices so the cows do not become agitated prior to examination. It is unrealistic to expect small operations to invest in costly upgrades to their cattle handling facilities, so lower-cost strategies should be prioritized. In some locations, veterinary practices could acquire transportable cattle containment equipment (ie, a mobile cattle chute) that practice staff could set up on the livestock operation the day before the reproductive examination appointment. This strategy has been adopted by many veterinary practices in the United States to ensure that veterinarians are working with a consistent set of well-maintained and fully operational equipment. That strategy has not been widely adopted by Canadian veterinary practices, but with appropriate adjustments to staffing and fee structure, it could be implemented.

Some veterinarians may find it difficult to ask cattle producers to restructure their cattle handling facilities or staffing plans during reproductive examination appointments. It may be difficult to motivate producers to make major changes for a task that requires only a few hours once a year. To address this issue, veterinarians should emphasize to the client the benefits of a safe and efficient working environment for both animals and people and point out that they perform reproductive examinations at dozens, if not hundreds, of cattle operations over the course of a season. On the basis of our observations during the present study, it appeared that veterinarians were sometimes exposed to unsafe situations. They might arrive at an operation with inadequate cattle handling facilities or farm personnel for the planned task and may be unwilling to potentially strain their relationship with the client by refusing to work in unsafe conditions. Or, veterinarians may simply choose to take a risk and work in suboptimal conditions to finish a job they had already driven several hours to get to, a strategy commonly described by rural farmers with chronic MSKD,31 rather than refuse to do the job until the facilities are fixed and have to fit another visit into a busy schedule. Prioritization of safety and advocation of risk mitigation techniques could be emphasized in veterinarian training programs so that new veterinarians come to expect safe work practices and environments. Experienced veterinarians could also mentor new veterinarians on how to advocate for their personal safety and well-being.

Currently, in most veterinary curricula, students are trained to use their nondominant arm for rectal palpation of cattle, but that may be detrimental in the long term. Owing to the inherent ergonomic hazards associated with reproductive examination of cattle, veterinarians may want to consider the use of both arms when faced with examining a large number of animals to reduce the physical burden on 1 arm. That strategy is consistent with the concept of job rotation, which is a common ergonomic intervention that potentially minimizes exposure to hazards by distributing it across different muscle groups.32 One veterinarian observed during the present study had adopted that approach and described a long career in large animal practice; therefore, it is a strategy worthy of further investigation. In human health care facilities, implementation of safe patient handling protocols reduces injuries to facility staff.33 The introduction of an evidence-based patient handling program for practicing and student veterinarians may also be helpful.

A participatory ergonomics approach should be used to develop injury prevention strategies, regardless of whether those strategies are technique-based or organizational, so veterinarians and cattle producers can take ownership of the interventions.34 A participatory ergonomics approach involves workers in development and implementation of solutions and has been consistently shown to have a positive effect on reducing employee MSKD in workplaces.35 However, the implementation of a participatory ergonomics approach across many independent livestock operations and veterinary practices versus a defined company or workplace would be challenging. Effective technical and organization strategies for injury prevention may already be in practice on a small scale. Unpublished data from a previous survey4 of Canadian bovine veterinarians conducted by our research group indicate that respondents have implemented multiple strategies, including altering body position and patient restraint techniques, to alleviate physical stress while performing reproductive examinations; these strategies should be investigated for more widespread use. Feedback from veterinarians on diverse techniques for mitigating work-related MSKD could be used to begin a conversation among interested parties and prioritize areas of focus for future intervention research and implementation.

Regardless of the strategies implemented, minimizing exposure of veterinarians to ergonomic hazards in large animal practice must be prioritized by the profession. Veterinarian demographics are changing. Although most bovine veterinarians in Canada are men,4 80% of current veterinary students in both Canada and the United States are women.36,37 Research indicates that, when women and men perform identical tasks, women are at greater risk for development of musculoskeletal disorders.38 The number of veterinarians observed in the present study was too small to draw any definitive conclusions about the relationship between MSKD and gender. Nevertheless, when veterinarians were exposed to similar external forces from cattle, the mean estimated entry force for the female participants of the present study was similar to that of the male participants. On average, the strength capacity of women is lower than that of men39; therefore, female veterinarians may need to expend a greater proportion of their strength than male veterinarians to perform reproductive examinations of cattle. Thus, the next generation of veterinarians might be more susceptible than is the current population of bovine veterinarians to the ergonomic hazards associated with reproductive examination of cattle unless adequate strategies for prevention of upper extremity MSKD are implemented.

Results of the present study confirmed that reproductive examination of cattle, regardless of whether it is performed by rectal palpation or use of a UEW, exposes veterinarians to repetitive awkward postures and forceful exertions that are similar to those associated with MSKD and injury in other occupations.17,18,19,20 In the present study, veterinarians were observed, particularly during beef appointments, performing secondary tasks in addition to examining cattle that exposed them to additional ergonomic hazards. The ergonomic hazards observed and estimated in this study should be validated by direct measurement or laboratory-based task simulations. However, the lack of direct measurement of the ergonomic hazards associated with reproductive examination of cattle should not prevent the veterinary community from initiating efforts to mitigate those hazards. A participatory ergonomics technique should be used to develop hazard mitigation strategies in collaboration with veterinarians. Those mitigation strategies should prioritize minimizing exposure to ergonomic hazards (ie, secondary tasks) not directly associated with reproductive examination of cattle.

Acknowledgments

Supported by the Canada Research Chairs Program (No. 228136) and University of Saskatchewan Department of Medicine Grant Program.

Funding sources did not have any involvement in the study design, data analysis and interpretation, or writing and publication of the manuscript.

The authors thank Dr. Saeed Shanehsazzadeh for assistance with collection of field data.

Footnotes

a.

MicroFET2 digital handheld dynamometer, Hoggan Scientific LLC, Salt Lake City, Utah.

Abbreviations

MSKD

Musculoskeletal discomfort

UEW

Ultrasound extension wand

WCABP

Western Canadian Association of Bovine Practitioners

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    Kozak A, Schedlbauer G, Peters C, et al. Self-reported musculoskeletal disorders of the distal upper extremities and the neck in German veterinarians: a cross-sectional study. PLoS One 2014;9:e89362.

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    Ergan M, Balkurt F, Balkurt Z. The examination of work-related musculoskeletal discomforts and risk factors in veterinarians. Arh Hig Rada Toksikol 2017;68:198205.

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    Rosati PM, Chopp JN, Dickerson CR. Investigating shoulder muscle loading and exerted forces during wall painting tasks: influence of gender, work height and paint tool design. Appl Ergon 2014;45:11331139.

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    Bayam L, Ahmad MA, Naqui SZ, et al. Pain mapping for common shoulder disorders. Am J Orthop (Belle Mead NJ) 2011;40:353358.

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    • Search Google Scholar
    • Export Citation
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    Granata KP, Marras WS, Davis KG. Variation in spinal load and trunk dynamics during repeated lifting exertions. Clin Biomech (Bristol, Avon) 1999;14:367375.

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    • Search Google Scholar
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    van der Beek AJ, Kuiper JI, Dawson M, et al. Sources of variance in exposure to nonneutral trunk postures in varying work situations. Scand J Work Environ Health 1995;21:215222.

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    • Search Google Scholar
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    • Search Google Scholar
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    Zalk DM. Grassroots ergonomics: initiating an ergonomics program utilizing participatory techniques. Ann Occup Hyg 2001;45:283289.

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  • Figure 1

    Representative photographs of reproductive examinations being performed on cattle by manual palpation and ultrasonographic examination of the reproductive tract per rectum (rectal palpation; A) and use of a UEW (B).

  • Figure 2

    Schematic depictions of arm inclination, which was used to assess veterinarians for extreme posture when performing reproductive examinations of cattle. Arm inclination was defined as elevation of the arm from a neutral position (arm hanging relaxed by the side of an upright individual; red line) in any plane. Arm inclination angles ≥ 60° and ≥ 90° were considered extreme postures for the veterinarians of this study.

  • Figure 3

    Representative photographs of commonly used methods to restrain cattle during reproductive examinations. A—Photograph of a manually operated cattle chute. To load the cow into the chute, the access (personnel) gate is closed and latched so the animal cannot escape out the side of the chute, and the head gate is opened. The cattle gate is opened to allow the cow to enter the chute, and the head gate is closed as the cow's head passes through it, preventing the animal from exiting the chute. The cattle gate is closed to prevent other cattle from entering the chute. This chute is equipped with a squeeze option, which is a mechanical feature that allows the sides of the chute to be drawn together to apply pressure on the sides of the animal to help calm it and prevent excessive side-to-side movement during examination. Once the animal is adequately restrained, the access gate is opened so the veterinarian can enter the chute behind the animal and perform the examination. B—Photograph depicting dairy cattle restrained in head locks for reproductive examination. Head locks are a series of connected stanchions that are generally permanently mounted along a feed alley. Cows must put their heads through the head locks to access feed. The stanchions can be set in a lock position to prevent cows from backing up and restraining them when necessary. When most of the head locks are occupied, side-to-side movement of the animals is minimized, and a veterinarian can perform reproductive examinations on a large group of cows in a fairly safe and efficient manner. C—Photograph depicting dairy cattle restrained in a palpation rail for reproductive examination. Cows are lined up immediately next to one another inside a palpation enclosure (approx 1.5 × 5 m). Cows are restrained by being crowded in and pressed against one another; a rope is tied behind the last cow to prevent the row of cows from exiting or moving laterally. The veterinarian performs reproductive examinations by reaching through the rails on the back side of the palpation enclosure.

  • 1.

    Fowler HN, Holzbauer SM, Smith KE, et al. Survey of occupational hazards in Minnesota veterinary practices in 2012. J Am Vet Med Assoc 2016;248:207218.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 2.

    Berry SL, Susitaival P, Ahmadi A, et al. Cumulative trauma disorders among California veterinarians. Am J Ind Med 2012;55:855861.

  • 3.

    Scuffham AM, Legg SJ, Firth EC, et al. Prevalence and risk factors associated with musculoskeletal discomfort in New Zealand veterinarians. Appl Ergon 2010;41:444453.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 4.

    Zeng X, Reist R, Jelinski M, et al. Musculoskeletal discomfort among Canadian bovine practitioners: prevalence, impact on work, and perception of physically demanding tasks. Can Vet J 2018;59:871879.

    • Search Google Scholar
    • Export Citation
  • 5.

    Ailsby RL. Occupational arm, shoulder, and neck syndrome affecting large animal practitioners. Can Vet J 1996;37:411.

  • 6.

    Cattell MB. Rectal palpation associated cumulative trauma disorders and acute traumatic injury affecting bovine practitioners. Bov Pract 2000;34:15.

    • Search Google Scholar
    • Export Citation
  • 7.

    Reist RM, Bath BL, Jelinski MD, et al. Risk factors associated with work-preventing musculoskeletal discomfort in the upper extremities of bovine practitioners. J Am Vet Med Assoc 2020;257:410416.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 8.

    Kozak A, Schedlbauer G, Peters C, et al. Self-reported musculoskeletal disorders of the distal upper extremities and the neck in German veterinarians: a cross-sectional study. PLoS One 2014;9:e89362.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 9.

    Ergan M, Balkurt F, Balkurt Z. The examination of work-related musculoskeletal discomforts and risk factors in veterinarians. Arh Hig Rada Toksikol 2017;68:198205.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 10.

    Rood KA, Pate ML. Assessment of musculoskeletal injuries associated with palpation, infection control practices, and zoonotic disease risks among Utah clinical veterinarians. J Agromedicine 2019;24:3545.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 11.

    Scuffham AM, Firth EC, Stevenson MA, et al. Tasks considered by veterinarians to cause them musculoskeletal discomfort, and suggested solutions. N Z Vet J 2010;58:3744.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 12.

    Reist R, Jelinski M, Bath B, et al. Up to our elbows in ergonomics: quantifying the risks of bovine rectal palpations, in Proceedings. 20th Congr Int Ergon Assoc 2018;639649.

    • Search Google Scholar
    • Export Citation
  • 13.

    Bernard B, Putz-Anderson V, Burt S, et al. CDC. Musculoskeletal disorders and workplace factors: a critical review of epidemiologic evidence for work-related musculoskeletal disorders of the neck, upper extremity, and low back. Available at: www.cdc.gov/niosh/docs/97–141/pdfs/97–141.pdf. Accessed Oct 12, 2020.

    • Search Google Scholar
    • Export Citation
  • 14.

    da Costa BR, Ramos Vieira E. Risk factors for work-related musculoskeletal disorders: a systematic review of recent longitudinal studies. Am J Ind Med 2010;53:285323.

    • Search Google Scholar
    • Export Citation
  • 15.

    Grandin T. Behavioral agitation during handling of cattle is persistent over time. Appl Anim Behav Sci 1993;36:19.

  • 16.

    Bao S, Silverstein B. Estimation of hand force in ergonomic job evaluations. Ergonomics 2005;48:288301.

  • 17.

    Wahlström J, Bergsten E, Trask C, et al. Full-shift trunk and upper arm postures and movements among aircraft baggage handlers. Ann Occup Hyg 2016;60:977990.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 18.

    Stenlund B, Lindbeck L, Karlsson D. Significance of house painters’ work techniques on shoulder muscle strain during overhead work. Ergonomics 2002;45:455468.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 19.

    Rosati PM, Chopp JN, Dickerson CR. Investigating shoulder muscle loading and exerted forces during wall painting tasks: influence of gender, work height and paint tool design. Appl Ergon 2014;45:11331139.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 20.

    Svendsen SW, Bonde JP, Mathiassen SE, et al. Work related shoulder disorders: quantitative exposure-response relations with reference to arm posture. Occup Environ Med 2004;61:844853.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 21.

    Bayam L, Ahmad MA, Naqui SZ, et al. Pain mapping for common shoulder disorders. Am J Orthop (Belle Mead NJ) 2011;40:353358.

  • 22.

    Hoozemans MJ, van der Beek AJ, Frings-Dresen MH, et al. Pushing and pulling in association with low back and shoulder complaints. Occup Environ Med 2002;59:696702.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 23.

    Granata KP, Marras WS, Davis KG. Variation in spinal load and trunk dynamics during repeated lifting exertions. Clin Biomech (Bristol, Avon) 1999;14:367375.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 24.

    van der Beek AJ, Kuiper JI, Dawson M, et al. Sources of variance in exposure to nonneutral trunk postures in varying work situations. Scand J Work Environ Health 1995;21:215222.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 25.

    Weston EB, Aurand A, Dufour JS, et al. Biomechanically determined hand force limits protecting the low back during occupational pushing and pulling tasks. Ergonomics 2018;61:853865.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 26.

    Canadian Centre for Occupational Health and Safety. Pushing & pulling—general. Available at: www.ccohs.ca/oshanswers/ergonomics/push1.html. Accessed Jul 8, 2019.

    • Search Google Scholar
    • Export Citation
  • 27.

    Pereira Lima ML, Negrão JA, de Paz CCP, et al. Minor corral changes and adoption of good handling practices can improve the behavior and reduce cortisol release in Nellore cows. Trop Anim Health Prod 2018;50:525530.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 28.

    Molenaar S, McKinnon C, Van Velzer CT. The use of force matching to quantify job demands, in Proceedings. 42nd Annu Conf Assoc Can Ergonomists 2013.

    • Search Google Scholar
    • Export Citation
  • 29.

    Dale AM, Rohn AE, Patton A, et al. Variability and misclassification of worker estimated hand force. Appl Ergon 2011;42:846851.

  • 30.

    National Institute for Occupational Safety and Health. Hierarchy of controls. Available at: www.cdc.gov/niosh/topics/hierarchy/default.html. Accessed Sept 14, 2019.

    • Search Google Scholar
    • Export Citation
  • 31.

    Bath B, Jaindl B, Dykes L, et al. Get ‘er done: experiences of Canadian farmers living with chronic low back disorders. Physiother Can 2019;71:2433.

  • 32.

    The Swedish Work Environment Authority. Ergonomics for the prevention of musculoskeletal disorders. Available at: www.av.se/globalassets/filer/publikationer/foreskrifter/engelska/ergonomics-for-the-prevention-of-musculoskeletal-disorders-afs-2012–2.pdf. Accessed Oct 12, 2020.

    • Search Google Scholar
    • Export Citation
  • 33.

    Restrepo TE, Schmid FA, Gucer PW, et al. Safe lifting programs at long-term care facilities and their impact on workers’ compensation costs. J Occup Environ Med 2013;55:2735.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 34.

    Zalk DM. Grassroots ergonomics: initiating an ergonomics program utilizing participatory techniques. Ann Occup Hyg 2001;45:283289.

  • 35.

    Rivilis I, Van Eerd D, Cullen K, et al. Effectiveness of participatory ergonomic interventions on health outcomes: a systematic review. Appl Ergon 2008;39:342358.

    • Crossref
    • Search Google Scholar
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