Age differences in energy absorption in the upper extremity during a descent movement: implications for arresting a fall.
BACKGROUND
Falls are the number one cause of unintentional injury in older adults. The protective response of "breaking the fall" with the outstretched hand is often essential for avoiding injury to the hip and head. In this study, we compared the ability of young and older women to absorb the impact energy of a fall in the outstretched arms.


METHODS
Twenty young (mean age = 21 years) and 20 older (M = 78 years) women were instructed to slowly lower their body weight, similar to the descent phase of a push-up, from body lean angles ranging from 15 degrees to 90 degrees . Measures were acquired of peak upper extremity energy absorption, arm deflection, and hand contact force.


RESULTS
On average, older women were able to absorb 45% less energy in the dominant arm than young women (1.7 +/- 0.5% vs 3.1 +/- 0.4% of their body weight x body height; p < .001). These results suggest that, even when both arms participate equally, the average energy content of a forward fall exceeds by 5-fold the average energy that our older participants could absorb and exceeds by 2.7-fold the average energy that young participants could absorb.


CONCLUSIONS
During a descent movement that simulates fall arrest, the energy-absorbing capacity of the upper extremities in older women is nearly half that of young women. Absorbing the full energy of a fall in the upper extremities is a challenging task even for healthy young women. Strengthening of upper extremity muscles should enhance this ability and presumably reduce the risk for injury to the hip and head during a fall.
Sran
Meena M
MM
Injury Prevention and Mobility Lab, Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, British Columbia, Canada.
Stotz
Paula J
PJ
Normandin
Sarah C
SC
Robinovitch
Stephen N
SN
D000058:Accidental Falls / Q000517:prevention & control*; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D001696:Biomechanical Phenomena; D001823:Body Composition; D005260:Female; D050723:Fractures, Bone / Q000209:etiology / Q000517:prevention & control; D006801:Humans; D009068:Movement / Q000502:physiology*; D011187:Posture / Q000502:physiology*; D012307:Risk Factors; D034941:Upper Extremity / Q000502:physiology*; D014954:Wrist Injuries / Q000209:etiology* / Q000503:physiopathology / Q000517:prevention & control; D014955:Wrist Joint / Q000503:physiopathology*; D055815:Young Adult