Rapid torque development in older female fallers and nonfallers: a comparison across lower-extremity muscles

The objective of this study was to compare reaction time, joint torque, rate of torque development, and magnitude of neuromuscular activation of lower-extremity muscles in elderly female fallers and nonfallers. Participants included 11, elderly, female fallers (71.3+/-5.4 years) and twelve nonfallers (71.3+/-6.2 years) who completed a fall risk questionnaire. Then, maximal, voluntary, isometric contractions of the knee and ankle muscles were performed in reaction to a visual cue to determine joint torque, rate of torque development, reaction time, and nervous activation of agonists and antagonists. Results indicated that significantly more fallers reported "dizziness upon rising", "use of balance altering medications", "stress or depression", "not enough sleep", "arthritis in lower body", "chronic pain in lower body", and "tiring easily while walking" (all P<0.05). Normalized dorsiflexion and plantarflexion strength scores (summation of peak torque, rate of torque development and impulse) were lower in fallers than in nonfallers (P<0.05). When summed across lower-extremity muscle groups, fallers demonstrated 19% lower peak torque and 29% longer motor time (P<0.05). In conclusion, comprehensive fall risk screening and prevention programs should address both neuromuscular and non-muscular factors, and, weakness of the ankle dorsiflexors and plantarflexors should be further studied as potential contributors to falls in older adults.