Explosive power and asymmetry in leg muscle function in frequent fallers and non-fallers aged over 65

Abstract

Background: although low strength is a risk factor for falls, lower limb explosive power is more predictive of functional difficulties than strength. Power may be more predictive of a future fall than strength per se.

Objective: to compare leg muscle strength and explosive power and asymmetry of leg strength and power of women aged 65 or over living at home, with and without a history of falls.

Design: a case controlled study of self-reported 'fallers' versus 'non-fallers'.

Subjects: twenty women, aged 65 or over, with a history of at least three falls in the previous year were age matched with 15 women with no history of falls in the previous year.

Methods: lower limb explosive power, isometric strength of the quadriceps and hamstrings, isokinetic concentric strength (100 degrees/sec) of the quadriceps, hamstrings, ankle plantar- and dorsi-flexors and quadriceps eccentric strength (100 degrees/sec). Habitual physical activity was assessed using the self-completed Habitual Activity Profile Questionnaire.

Results: the women with a history of falls were less active but were not significantly weaker in any of the strength measurements, apart from ankle dorsiflexion adjusted for body weight. Both groups had significant asymmetry in all the leg muscles for both strength and power. Although both groups were asymmetrical in their lower limb power, the fallers demonstrated a significantly greater asymmetry. When the least powerful legs were compared, the women with a history of falls were 24% less powerful for their weight than those who did not fall (P=0.04).

Conclusions: weakness and asymmetry is prevalent in women aged 65 and over, with and without a history of falls. Poor lower limb explosive power combined with asymmetry between limbs may be more predictive of future falls than more traditional measurements of strength in older women who live independently.