Human Factors-Based Development of a Pediatric Elliptical Machine for Rehabilitation and Fitness
TimeThursday, April 152:00pm - 3:00pm EDT
Elliptical trainers are used for both low impact exercise and rehabilitation, to create movement similar to joint motions and muscle activities required in gait (Buster, Burnfield, Taylor, & Stergiou, 2013; Nelson et al., 2011). Children with various physical limitations and chronic conditions, who face movement and walking difficulties. An elliptical machine – specifically designed for the pediatric population – could benefit children by helping to overcome limited mobility for rehabilitation, and strength and conditioning (Burnfield et al., 2018). The use of elliptical machines enables children to walk longer distances, making it easier for them to engage in community activities, and enhance their quality of life (Garbin, Eckels, Buster, & Burnfield, 2017).
However, lack of usability of elliptical trainers may create inefficiency in use and reduce benefits for the users. Some work has been done on the human factors and ergonomics associated with the usability and impacts of elliptical trainers (Garbin et al., 2017; Shu et al., 2010). Despite elliptical machines’ potential to enhance physical functionality, comfort and safety, there has been no research conducted on the interaction between pediatric elliptical machines and children of different ages and abilities. Commercially available elliptical trainers do not fully accommodate the physical, cognitive, and temporospatial stride characteristics of children over a wide range of ages and abilities. Therefore, this study focused on the ergonomic design of the machine, to offer customized use based on the user’s age, enhancing the interaction of the users with the machine. The objectives of the study were to incorporate adjustability into the machine, to make the machine easy to understand and operate, to make it comfortable for the children while using, to ensure safety, and to make it more engaging and motivating for the children.
A commercially available pediatric elliptical trainer was used for evaluation and redesign. An ergonomic study, approved by the Institutional Review Board, was conducted at a Rehabilitation hospital to evaluate the elliptical’s ergonomics for children with age of 3 to 12 years. Eleven (11) typically developing children and seventeen (17) children with physical disabilities and/or chronic conditions participated in the study. To design the elliptical to meet the needs of children with different physical abilities and limitations, anthropometric and clinical (functional) measurements were conducted with each participant prior to testing. Additionally, temporospatial stride characteristics, including step length and base of support, were collected using the GAITRite portable Gait Analysis System (CIR Systems, Inc., Sparta, NJ).
Based on the participant’s anthropometric, clinical, and gait measures, modifications made to the elliptical by improving various features or adding some. Under close supervision by the investigators, each child used the elliptical prior to and after modification. Kinematic pedal trajectories were recorded after modification at each manually adjustable step length of 9cm, 19cm, 29cm, and 39cm.
Structured interviews using comprehensive surveys were conducted of the users (children, caregivers, clinicians) to assess the modifications made to the pediatric elliptical machine. Moreover, pictures and videos of the children, captured while using the elliptical, were assessed to understand how they interact with the machine.
Collected data were analyzed using Minitab (V19, Minitab, LLC, State College, PA) software. Frequency analysis was performed of the children’s data, adults’ data and clinicians’ data to assess the satisfaction of the users on the various design factors of the machine. Additionally, clinician data and adult data were analyzed to assess the association of the design factors with the use experience of the users. Chi-square test was run for each of the two-way tables prepared by cross connecting the various aspects of use experience with each of the design factors.
Half of the features, (i.e., chair height, chair depth, console height, stride length, pedal straps and steps height etc.) resulted in similar child and adult use assessment. However, six features, (i.e., stationary handle’s height, moving handle’s height, moving handle width, stride width, and pedal length) resulted in divergent user responses. Clinicians were satisfied with the positioning of chair, stationary handles, pedal and pedal straps. However, the clinicians wanted further improvements to the chair depth and height of reciprocating handles and console height. Overall, the elliptical’s redesign resulted in user comfort, improved safety and better gait-specificity. Modifications to the pediatric elliptical allowed it to more closely replicate the temporospatial stride demands of over-ground walking for 3- to 12-year-old children with and without physical disabilities and/or chronic conditions. Some users (older children without disabilities) were not as physically challenged due to a limited stride length of the current prototype (p = 0.044). Future elliptical prototype will include a stride length of 40 cm to 110 cm to accommodate children aged 3 to 12 (Assi, Ghanem, Lavaste, & Skalli, 2009; Croarkin et al., 2009; Wondra, Pitetti, & Beets, 2007).
Children with or without physical disabilities and chronic conditions benefited from sustained engagement in appropriately challenging physical activity by strengthening muscles and bones, and improving walking ability, and can attain health and emotional well-being (Murphy & Carbone, 2008). In this study, a commercially-available pediatric elliptical machine was redesigned and then based on the users’ feedback. Additional modifications were suggested to include an automated stop switch, automated stop switch, adjustments instructions to the machine based on the child height and physical functionality and a greater adjustability for stride length. These additional enhancements will improve rehabilitation using an elliptical machine.