Effect of Individual and Work-Related Risk Factors on Hand Grip Strength During Pruning Task of Greenhouse Farmers

OBJECTIVES: Greenhouse pruning involves repetitive hand movements, sustained grip force, and prolonged exposure to heat, placing farmers at risk of work-related musculoskeletal disorders. This study examined the effects of individual, work-related, and environmental factors on hand grip strength (HGS) among greenhouse farmers during pruning tasks. METHODS: A field-based repeated-measures study was conducted among 100 greenhouse farmers performing tomato-pruning activities under real-time greenhouse conditions. HGS was measured six times daily over a 15-day pruning period using a digital hand dynamometer for both hands. Anthropometric variables, pruning tool type, and environmental temperature were recorded. Hierarchical linear mixed-effects modelling was performed to account for within-subject variability across repeated work phases and working days. RESULTS: Mean HGS was 32.55 ± 5.41 kg for the dominant hand and 28.24 ± 5.05 kg for the non-dominant hand. Dominant hand usage, gender, and forearm-to-hand length were the strongest predictors of HGS. HGS progressively declined across work phases, with an overall reduction of approximately 7.6% from morning to evening work periods. Male participants demonstrated consistently greater HGS values than female participants. HGS was significantly associated with anthropometric characteristics. Indoor greenhouse temperature demonstrated a weak negative but statistically non-significant association with HGS. CONCLUSION: Repetitive greenhouse pruning tasks contribute to progressive reductions in HGS during prolonged work periods. Anthropometric characteristics and pruning tool design substantially influence grip performance during pruning activities. The findings support ergonomic interventions, including optimized tool design, task-specific training, and work-rest scheduling, to reduce cumulative upper-extremity loading and improve occupational health among greenhouse farmers.