Designing an ergonomic watering tool and electromyographic assessment of its effect on the upper limb muscle activity

Background Manual watering involves prolonged gripping, repetitive wrist motions, and static postures, potentially contributing to musculoskeletal disorders. Objective To design an ergonomic watering tool and compare its effects on upper-limb muscle activity with two conventional methods using surface electromyography (sEMG). Methods Fifteen healthy males performed standardized watering tasks using a garden hose, a commercial spray nozzle, and the novel ergonomic tool. sEMG was recorded from the biceps brachii, triceps brachii, upper trapezius, and wrist flexors. Amplitude-domain (RMS, mean, median, peak) and frequency-domain (MNF, MDF) parameters were analyzed using repeated-measures ANOVA with post-hoc tests. Results No significant differences were observed among conditions for the biceps, triceps, or trapezius (p > 0.05). However, significant differences were found for all wrist flexor parameters: RMS (F = 28.41, p < 0.001, η 2 = 0.686), mean amplitude (F = 27.49, p < 0.001, η 2 = 0.647), median amplitude (F = 19.04, p < 0.001, η 2 = 0.576), peak amplitude (F = 11.45, p = 0.001, η 2 = 0.417), MNF (F = 8.10, p = 0.002, η 2 = 0.366), and MDF (F = 17.25, p < 0.001, η 2 = 0.497). Post-hoc analyses indicated significantly lower wrist flexor activity with the ergonomic tool versus both conventional methods, with no differences between the hose and nozzle. Conclusions The ergonomic tool substantially reduced wrist flexor demand during laboratory tasks, likely through improved forearm support and load distribution. Field studies with agricultural workers and extended durations are needed before broader occupational recommendations can be made.