Redesign and ergonomic assessment of a chest-support baby walker.

BACKGROUND: Parents often use baby walkers (BWs) as assistive devices to improve their infants' independent movement and motor skill acquisition. However, the literature suggests that conventional baby walkers (CBW) may cause delays in an infant's ability to walk independently and musculoskeletal burden on parents. OBJECTIVE: In the current study, a baby walker (RBW) with chest support was redesigned and ergonomically assessed during an infant-walking task. METHODS: The anthropometric dimensions of 90 infants aged 7-11 months were measured in the city of Urmia, northwestern Iran. Following redesigning based on the results from expert panel meetings and prototyping of the RBW, 18 mothers (age: 28.33±4.27 and height: 163.75±5.32 and weight: 59.45±5.99) with their infants (9 boys and 9 girls) performed a simulated infant walking task in two experimental sessions using the CBW and RBW over a repeated measurements design. The infants' feet track patterns, including the number of steps and step distances were assessed via the image analysis of the footprints. The mothers' body posture and lower back spinal load were evaluated using Rapid Upper Limb Assessment (RULA) technique and 3D Static Strength Prediction Program (3DSSPP), respectively. RESULTS: Wilcoxon signed-rank tests showed infants walked more steps with the RBW (p = 0.002). Similarly, the distance between the infants' left heel strike (p = 0.008) and their right and left toe-off (p = 0.03 and 0.02 respectively) was also significantly lower in the RBW use. Additionally, the body posture of mothers was improved (RULA final score from 7 for CBW to 5 for RBW). Moreover, lower back compression and shear forces were reduced significantly (p = 0.002) by the RBW use. CONCLUSION: According to the feet track pattern, infants took more balanced steps when the RBW was used. In addition, mothers were subjected to less pressure on the lumbar region when they placed and lifted their infant from the RBW. However, further work is necessary to investigate potential long-term effects of the RBWs use.

Prevalence of musculoskeletal disorders, working conditions, and related risk factors in the meat processing industry: Comparative analysis of Iran-Poland.

BACKGROUND: Activities performed by people in the meat processing industry are very repetitive, time-consuming, dangerous, and require long-term downtime during a shift (forced-static position). OBJECTIVES: This study aims to assess the prevalence of musculoskeletal disorders and working conditions among Polish and Iranian workers to fill this research gap. METHODS: A comparative analysis of the prevalence of musculoskeletal disorders (MSDs) in developed and developing countries was conducted. After selecting the target factories, data was collected using Nordic and Mental Stress Questionnaires and 3DSSPP software with the participation of 110 meat processing workers, including 55 Iranian and 55 Polish. RESULTS: This study showed nearly the same prevalence of MSDs among male Iranian and Polish workers, especially in elbow, wrist/hand, upper back, hip/thigh, and ankle/foot. The overall prevalence of MSDs was relatively high and connected to the lower back (38%, 64%), knee (40%, 24%), neck (24%, 42%), and upper back (24%, 34.5%), among Iranian and Polish workers, respectively. Assessment of logistic regression disclosed that the workplace is considerably associated with the elbow and the ankle/foot musculoskeletal pain, with 2.34 and 3.81 times more likely for the production room, respectively, among Iranian workers. CONCLUSION: Age, gender, type of occupation, work experience, smoking, insufficient physical activity, workplace, working postures, and stress level all affected the likelihood of MSDs happening in various body regions in both countries, implying that both individual and work-related (both physical and psychosocial) aspects should be taken into consideration when evaluating and managing such complaints in this workforce.

Evaluation of working conditions, work postures, musculoskeletal disorders and low back pain among sugar production workers.

BACKGROUND: It is generally agreed that musculoskeletal disorders (MSDs) are a severe health concern, particularly for agricultural laborers. OBJECTIVES: The study aimed to identify risk factors and work-related disorders among agricultural workers at Amirkabir agro-industry company in Iran. METHOD: A total of 158 workers, of which 66 were manual harvesting workers (four postures), 40 were fertilizer transportation workers (three postures), and 52 were spraying workers (one posture), were included in the study. The research used questionnaires to collect data, and the postures were analyzed using 3DSSPP software. Related risk factors such as age, body mass index, work experience, working hours, and sports activity were analyzed. RESULTS: The incidence rate of lower back pain (94%), knee pain (82%), neck pain (69%), upper-back (63%), and shoulder (63%) were calculated. The logistic regression revealed that working hours and sports activities are significantly correlated to the wrist/hand and neck MSD with 5.62 and 6.38 times more likely among manual harvesting workers. The 3DSSPP software estimated that the lower back pain, especially in the first posture, for manure transportation workers was very high. Maximum L5-S1 compression, shear, and moment forces in the first posture among manure transportation workers were 7113 N and 472 N, -381 N-m, respectively. CONCLUSION: The 3DSSPP results also illustrated that compression, shear, and moment forces exceeded the NIOSH limit for the other postures. After interventions, compression, shear, and moment forces among all farm workers decreased. These findings emphasize that farm workers need to be under surveillance continuously at their workstations where interventions and improvement in specific tasks are required.