Investigation on hand twisting force developed by the Indian elderly for opening different kinds of bottle packaging

Most liquid, semi-solid or granular foods are bottled to preserve and protect from external impacts. But, `open-ability' of packaging is a major issue for the elderly. Most of the elderly population experience problems in opening a bottle or jar, as they are unable to develop sufficient hand twisting force. The required force is far beyond their capacity. It is, therefore, essential to understand the biomechanical abilities of the elderly population for generating hand twisting force. The aim of this study was to determine the maximum hand twisting force can be generated by the elderly when opening a jar, medicine bottles or other type of bottles. The study was carried out on senior citizens from age range of 65 to 75 years. The age range was divided into groups, 65-70 and 70-75 years. The torque was measured using a calibrated torque transducer. To make the study realistic, a bottle-shaped unit containing a torque transducer internally was used that could easily be picked up and handled like regular activities. To explore the impact of different combinations of closure and base dimension, each volunteer underwent trials in 18 conditions, where the base diameter was 50, 60, 70, 80 and 100 mm and closure diameter was 30, 40, 60, 80, 100 mm. The diameter of the bases, closures and their combinations was derived based on market survey of 130 hand held bottle samples. In each trial, the torque exertion was repeated for three times in between a rest period of 1 minute and between two consecutive trials a rest of 3 minute was given to the elderly to avoid fatigue. The voltage obtained from the transducer was converted to torque data by using a prediction equation `Torque = (0.8309*volt) + 0.0164', developed while calibrating the torque transducer. The torque data were later converted to force data. The torque data were gathered through BIOPAC `AcqKnowledge' software (version 3.7.3) and all statistical analysis were performed using `OriginPro 8.5.1' software. The anthropometric profile of the elderly was studied and no significant variation was observed in the hand dimension of the elderly of different age groups. Statistical analysis of the force data indicated that the hand twisting force exerted by the male elderly of 65-70 years was significantly higher than both the male and female elderly group of 70-75 years (p<;0.05), which is natural phenomenon. But, no significant difference had been observed between the male and female elderly of the age 70-75 years. The mean twisting force was observed maximum with the bottle of 50 mm base and 80 mm closure diameter for both the gender of two age groups (age 65-70 years, 3.72 kg and age 70-75 years, 2.01 kg). Similarly, for both the age groups the mean hand twisting force observed minimum with the bottle of 100 mm base and 30 mm closure diameter (age 65-70 years, 1.20 kg and age 70-75 years, 0.73 kg). It was also observed that for each base, the hand twisting force increased with the increase of the closure diameter. The hand twisting force decreased with increase of the base diameter. It was noted that the minimum hand twisting force exerted by the elderly of different age groups are very similar but, a wide range of variation was observed in the maximum. The range of hand twisting force for 65-70 years age group varied from 0.3-5.7 kg and 0.5-14.0 kg for the female and male elderly respectively. The same for the 70-75 years age group varied from 0.4-2.6 kg for the female and 0.5-6.3 kg for the male elderly.