Effects of combined lower-extremity resistance and balance exercises in older women

Abstract

Purpose. This study compared the effects of lower-extremity resistance exercise combined with either step or static balance exercise on strength and balance in older women. Methods. 27 community-dwelling older women completed a 10-week lower-extremity exercise programme combining resistance exercise with either a step (n=11) or static (n=16) balance exercise. Lower-extremity strength was evaluated using the 30-second chair stand test. Balance was assessed using the one leg stance test, multi-directional reach test, timed up and go test, and four square step test. Results. Respectively for the step and static exercise groups, the 30-second chair stand test for lower-extremity strength improved 36% and 24%, whereas the timed up and go test for balance improved 4% and 8% (with no interaction effect), and the four square step test for balance improved 21% and 1% (with interaction effect). Conclusion. A 10-week combined lower-extremity resistance and balance exercise programme may improve strength in older women, but improvement in balance varies depending on the balance exercise. The risk of fall may be reduced by a combination of resistance and balance exercises.

Headnote

ABSTRACT

Purpose. This study compared the effects of lower-extremity resistance exercise combined with either step or static balance exercise on strength and balance in older women.

Methods. 27 community-dwelling older women completed a 10-week lower-extremity exercise programme combining resistance exercise with either a step (n=11) or static (n=16) balance exercise. Lower-extremity strength was evaluated using the 30-second chair stand test. Balance was assessed using the one leg stance test, multi-directional reach test, timed up and go test, and four square step test.

Results. Respectively for the step and static exercise groups, the 30-second chair stand test for lower-extremity strength improved 36% and 24%, whereas the timed up and go test for balance improved 4% and 8% (with no interaction effect), and the four square step test for balance improved 21% and 1% (with interaction effect).

Conclusion. A 10-week combined lower-extremity resistance and balance exercise programme may improve strength in older women, but improvement in balance varies depending on the balance exercise. The risk of fall may be reduced by a combination of resistance and balance exercises.

Key words: Aged; Exercise; Muscle strength; Postural balance; Women

INTRODUCTION

Approximately one-third of people over 65 years of age experience falls each year, and approximately 10% of falls result in fracture.1 Of all fall-related fractures, 55% occur at the hip2 and 18% at the radius.3 Fractures have a considerable impact on the cause of illness, disability, and death in the elderly.4 In addition, falls in older adults lead to loss of self-confidence and independence.5 Thus, falls in older adults are a major public-health concern and fall prevention is important.

Risk factors that contribute to falls in older adults include extrinsic factors related to the environment (slippery floors and poor lighting) and intrinsic factors related to functional capacity (muscle weakness, impairments in balance or gait, vision or sensory disorders, vestibular disorders, decreased cognition, and medication).6,7 Lower-extremity muscle weakness and balance deficits are among the major intrinsic risk factors for falls.8,9 Muscle weakness is also associated with increased disability and a decline in function and balance.10 Good balance is essential for most activities of daily living (ADLs).11

Combined exercises with strength and balance components have a greater effect on fall prevention than other types of exercise such as aerobic training.12 Combined resistance and balance exercises (reaching, weight shifting through activity, marching in place, and stepping) improve both muscle strength and balance.13 Balance is the ability to maintain the projection of the body's centre of mass within manageable limits of the base of support, as in standing or sitting, or in transit to a new base of support, as in walking.14 Different combinations of strategies have been used to develop balance exercises for older adults (e.g. tandem stance, stepping, and dual tasks).15 This study compared the effects of lower-extremity resistance exercise combined with either step or static balance exercise on strength and balance in older women.

METHODS

This study was approved by the ethical committee of Seijoh University (2007C0004, 2008C0001); written informed consent was obtained from each participant. 34 community-dwelling older women aged >65 years who could stand and walk independently were assigned to undergo lower-extremity resistance exercise combined with either a step (n=15) or static (n=19) balance exercise. Those advised by their physician to refrain from exercise were excluded. 11 and 16 participants in the respective groups completed the study. Four participants dropped out due to fracture (n=1), low back pain (n=1), and other reasons (n=2), and 3 participants did not complete the post-test due to schedule conflicts.

The programme lasted for 10 weeks (one session at centre and 2 sessions at home per week) and included a warm-up (10 mins), balance exercises (30 mins), lower-extremity resistance exercises (one set of 12 repetitions) using elastic bands (30 mins), and cool down (10 mins). The intensity of the resistance exercises was rated using Borg's rate of perceived exertion (RPE) scale.16 Participants were asked to perform at an RPE of 11 to 13 for the first 3 weeks and then at 15 for 4 weeks. For step balance exercises, participants stepped forwards and backwards or from side to side over a bar made of rolled newspapers, changing direction on the instructor's cue. The speed increased progressively during the exercise session. For the static balance exercises, participants performed neck rotations with eyes open or closed in a tandem stance on a firm surface for first 3 weeks and then on a foam pad for 4 weeks. Participants were asked to perform the same exercises at the same intensity at home.

The height and weight, characteristics, comorbidity, exercise habit, lower-extremity strength, and static and dynamic balance of the participants were examined. Lower-extremity strength was evaluated using the 30-second chair stand test (in times/30 seconds).17 Static balance was measured using a one-leg stance test (in seconds) with closed eyes.18 Dynamic balance was measured using the multi-directional reach test (in cm),19 the timed up and go test (in seconds),17 and the four square step test (in seconds).20

The 2 groups were compared using unpaired f-test or Chi-square test. Repeated-measures analysis of variance (ANOVA) was used for the time x group effect. The interaction effect was determined by comparing pre- and post-intervention difference for each group using the paired f-test. Effect size was then calculated. A p value of <0.05 was considered statistically significant. When there was a significant difference in baseline characteristics of the 2 groups, analysis of covariance (ANCOVA) was used for dependent variables.

RESULTS

The 2 groups differed significantly in terms of age (Table i). Therefore, the percentage change was a dependent variable, and the age was a covariate for all measurements. Regression slopes were homogeneous and no differences in the slope of the regression lines were found, except for the multi-directional reach test in the forward direction. For that test, there was an interaction between the dependent variable according to the group and the covariate. Therefore, ANCOVA was used without entering age as a covariate in all measurements.

The step and static exercise groups were comparable in terms of home exercise frequency for resistance exercise (1.7±1.5 vs. 0.9±1.0 day/week) and balance exercise (1.2±1.4 vs. 1.3±1.5 day/week).

The 2 groups differed significantly at baseline in terms of the 30-second chair stand test and the four square step test results (Table 2). Therefore, the effect of the 2 tests was determined using ANCOVA, with the pre-intervention value as a covariate. An interaction effect was noted for the four square step test, with the step exercise group improving more than the static exercise group (21% vs. 1%, F=19.38, p<0.001). In the step exercise group, the four square step test result improved significantly from 8.1 to 6.3 seconds (p=0.001, effect size=1.5). No interaction effect was noted for the 30-second chair stand test, the timed up and go test, one leg stance test, or the multi-directional reach test. The 30-second chair stand test result improved significantly from 12.8 to 17.1 times/30 seconds (p=0.012, effect size=0.9) in the step exercise group and from 17.9 to 21.5 times/30 seconds (p<0.001, effect size=1.3) in the static exercise group. The timed up and go test result improved significantly from 4.8 to 4.4 seconds (p<0.001, effect size=1.2) in the static exercise group. Neither group showed any improvement in the one leg stance test or the multi-directional reach test.

DISCUSSION

Both groups demonstrated improvement in lower-extremity strength measured by the 30-second chair stand test, with an equal effect size, whereas improvement in balance differed between the step and static exercise groups. Resistance exercises using elastic bands improve muscular strength and mass in older adults.21,22 Weakness in the lower-extremity muscles is a major risk factor for falls in older people,8,9 and is associated with physical disability in regular and instrumental ADLs.23,24

The timed up and go test result improved more in the static exercise group than the step exercise group (with no interaction effect). The timed up and go test is a composite functional measurement.18 An increase in more accurate postural control improves dynamic balance.25 In addition, it can be used as a marker of frailty,26,27 and can be a predictor of difficulty with ADLs and increased risk of falls.28,29 Therefore, static balance exercise, combined with lower-extremity resistance exercise, may improve the physical function for ADLs and reduce the risk of falls.

An interaction effect was noted on the four square step test results, with the step exercise group improving more than the static exercise group. Stepping measures (maximal step length test and rapid step test) improve significantly following a 10-week programme of combined balance exercise and stepping training.30 In addition, step training can improve initiation time and step length.31 Most falls in community-dwelling older adults occur secondary to trips and slips during movement.32 Step exercises that improve rapid stepping ability may thus be effective in reducing falls that result from trips and slips in older adults.

This study had several limitations. All participants were from the same community. Participants were not randomised to the treatment group, and thus the results may not be generalised. The sample size was small and unbalanced and may lead to type-II error. Age of participants differed significantly, although most results were not affected by age. Nonetheless, for the multi-directional reach test in the forward direction, there was an interaction effect between the dependent variable (the percentage change) according to the group and age.

CONCLUSION

A 10-week combined lower-extremity resistance and balance exercise programme may improve strength in older women, but improvement in balance varies depending on the balance exercise. The risk of fall may be reduced by a combination of resistance and balance exercises.

ACKNOWLEDGEMENTS

This study was supported by grants from the Seijoh University.

References

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