title: Motor readiness and joint torque production in lower limbs of older women fallers and non-fallers.
abstract: This study aimed to evaluate the motor response time and ability to develop joint torque at the knee and ankle in older women with and without a history of falls, in addition to investigating the effect of aging on these capacities. We assessed 18 young females, 21 older female fallers and 22 older female non-fallers. The peak torque, rate of torque development, rate of electromyography (EMG) rise, reaction time, premotor time and motor time were obtained through a dynamometric assessment and simultaneous electromyography. Surface EMGs of the rectus femoris (RF), vastus lateralis (VL), biceps femoris (BF), gastrocnemius lateralis (GL) and tibialis anterior (TA) muscles were recorded. Knee extension and flexion peak torques were lower in older fallers than in non-fallers. Knee extension and flexion and ankle plantarflexion and dorsiflexion peak torques were lower in both older groups than in the younger group. The rate of EMG rise of the BF and the motor time of the TA were lower and higher, respectively, in older fallers than in the younger adults. The time to reach peak torque in knee extension/flexion and ankle plantarflexion/dorsiflexion and the motor times of the RF, VL, BF and GL were higher in both older groups than in the younger groups. The motor time of the TA during ankle dorsiflexion and the knee extension peak torque were the major predictors of falls in older women, accounting for approximately 28% of the number of falls. Thus, these results further reveal the biomechanical parameters that affect the risk of falls and provide initial findings to support the prescription of exercises in fall prevention programs.
authors.affiliation: Department of Physical Education, São Paulo State University, Rio Claro, São Paulo, Brazil. lucianoeduca@gmail.com
authors.forename: Luciano Fernandes
authors.initials: LF
authors.lastname: Crozara
authors.forename: Mary Hellen
authors.initials: MH
authors.lastname: Morcelli
authors.forename: Nise Ribeiro
authors.initials: NR
authors.lastname: Marques
authors.forename: Camilla Zamfolini
authors.initials: CZ
authors.lastname: Hallal
authors.forename: Deborah Hebling
authors.initials: DH
authors.lastname: Spinoso
authors.forename: Antônio Francisco
authors.initials: AF
authors.lastname: de Almeida Neto
authors.forename: Adalgiso Coscrato
authors.initials: AC
authors.lastname: Cardozo
authors.forename: Mauro
authors.initials: M
authors.lastname: Gonçalves
mesh_terms: D000058:Accidental Falls; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D000843:Ankle Joint / Q000502:physiology; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000502:physiology*; D007866:Leg / Q000502:physiology*; D035002:Lower Extremity / Q000502:physiology; D008875:Middle Aged; D009119:Muscle Contraction / Q000502:physiology*; D053580:Muscle Strength / Q000502:physiology; D018482:Muscle, Skeletal / Q000502:physiology*; D005082:Physical Exertion / Q000502:physiology; D016059:Range of Motion, Articular / Q000502:physiology; D011930:Reaction Time / Q000502:physiology*; D019415:Torque; D055815:Young Adult
keywords: Falls; Muscle activation; Peak torque; Rate of torque development