Strength data for female shield-activated autoinjector users

BACKGROUND: Shield-activated autoinjectors are common for self-administration of medication, but data describing the strength required for their operation remain scarce. This study quantifies the maximum force capabilities of female autoinjector users. RESEARCH DESIGN AND METHODS: The study crossed three variables: age group (young adolescents, adults, elderly), grip type (power grip, precision grip), and injection site (abdomen, thigh, upper arm). A sample of 123 female United States residents completed six simulated injections using surrogate autoinjectors measuring maximum force (activation force) and mean force at fixed intervals (hold force). RESULTS: The primary results are statistics characterizing the activation and hold force exerted by each group across grip types and injection sites. Adults generally exerted higher activation forces but no significant differences were observed between adolescents and elderly. All participants exerted higher activation forces using power grip regardless of injection site, and injections in the thigh might allow for the highest forces when using power grip, but precision grip forces were less dependent on injection site. CONCLUSIONS: The study provides ecologically valid strength data for female users that can inform force specifications for shield-activated autoinjectors and inform training materials by identifying optimal grip types and injection sites for maximizing force.