Lauren J Lattimer1, Joel L Lanovaz2, Jonathan P Farthing3, Stéphanie Madill4, Soo Y Kim5, Stephen Robinovitch6, Catherine M Arnold7. 1. College of Kinesiology, University of Saskatchewan, 87 Campus Dr., Saskatoon, SK S7N 5B2, Canada. Electronic address: lauren.lattimer@usask.ca. 2. College of Kinesiology, University of Saskatchewan, 87 Campus Dr., Saskatoon, SK S7N 5B2, Canada. Electronic address: Joel.Lanovaz@usask.ca. 3. College of Kinesiology, University of Saskatchewan, 87 Campus Dr., Saskatoon, SK S7N 5B2, Canada. Electronic address: jon.farthing@usask.ca. 4. School of Physical Therapy, University of Saskatchewan, Suite 3400, 104 Clinic Place, Saskatoon, SK S7N 2Z4, Canada. Electronic address: Stephanie.madill@usask.ca. 5. School of Physical Therapy, University of Saskatchewan, Suite 3400, 104 Clinic Place, Saskatoon, SK S7N 2Z4, Canada. Electronic address: soo.kim@usask.ca. 6. School of Engineering Science, Simon Fraser University, 8888 University Drive, Burnaby, BC V5A 1S6, Canada. Electronic address: stever@sfu.ca. 7. School of Physical Therapy, College of Medicine, Suite 3400, 104 Clinic Place, University of Saskatchewan, Saskatoon, SK S7N 2Z4, Canada. Electronic address: cathy.arnold@usask.ca.
Abstract
BACKGROUND: Falling on the outstretched hands, a protective mechanism to arrest the body and avoid injury, requires upper limb and trunk motor control for effective body descent. Older women are particularly susceptible to injury from a forward fall, but the biomechanical and physiological (e.g., muscle strength) factors related to this increased risk are poorly understood. Determining age differences in the modifiable neuromuscular factors related to a forward fall landing and descent could help to inform injury prevention strategies. The purpose was to investigate age related differences in upper extremity strength and fall arrest strategy differences during a simulated fall and to evaluate the relationships between muscle strength and biomechanical variables. METHODS: Nineteen younger (mean age 23.0 yrs., SD 3.8) and 16 older (mean age 68.2 yrs., SD 5.3) women performed five trials of simulated falls. Biomechanical measures and electromyographic muscle activity were recorded during the descents. Concentric, isometric and eccentric strength of the non-dominant upper limb was measured via a dynamometer using a customized protocol. FINDINGS: Older women demonstrated lower concentric elbow extension strength compared to younger women (p = 0.002). Landing strategies differed where younger women had significantly greater elbow joint angle (p = 0.006) and velocity (p = 0.02) at impact. Older women demonstrated diminished capacity to absorb energy and control descent on outstretched hands compared to younger women (p = 0.001). INTERPRETATION: The landing strategy used by older women along with decreased energy absorption may increase risk of fall-related injury and increase the likelihood of trunk or head impact with the ground.
BACKGROUND: Falling on the outstretched hands, a protective mechanism to arrest the body and avoid injury, requires upper limb and trunk motor control for effective body descent. Older women are particularly susceptible to injury from a forward fall, but the biomechanical and physiological (e.g., muscle strength) factors related to this increased risk are poorly understood. Determining age differences in the modifiable neuromuscular factors related to a forward fall landing and descent could help to inform injury prevention strategies. The purpose was to investigate age related differences in upper extremity strength and fall arrest strategy differences during a simulated fall and to evaluate the relationships between muscle strength and biomechanical variables. METHODS: Nineteen younger (mean age 23.0 yrs., SD 3.8) and 16 older (mean age 68.2 yrs., SD 5.3) women performed five trials of simulated falls. Biomechanical measures and electromyographic muscle activity were recorded during the descents. Concentric, isometric and eccentric strength of the non-dominant upper limb was measured via a dynamometer using a customized protocol. FINDINGS: Older women demonstrated lower concentric elbow extension strength compared to younger women (p = 0.002). Landing strategies differed where younger women had significantly greater elbow joint angle (p = 0.006) and velocity (p = 0.02) at impact. Older women demonstrated diminished capacity to absorb energy and control descent on outstretched hands compared to younger women (p = 0.001). INTERPRETATION: The landing strategy used by older women along with decreased energy absorption may increase risk of fall-related injury and increase the likelihood of trunk or head impact with the ground.
Authors: Catherine M Arnold; Joel Lanovaz; Jonathan P Farthing; Hayley Legg; Melanie Weimer; Soo Kim Journal: Clin Rehabil Date: 2022-03-15 Impact factor: 2.884