Velocity training induces power-specific adaptations in highly functioning older adults

OBJECTIVE

To test the efficacy of high-velocity training in healthy older persons.

DESIGN

A 12-week randomized trial, with subjects blocked for gender and residence, comparing high-velocity resistance training with a self-paced walking program.

SETTING

Retirement community.

PARTICIPANTS

Forty-three volunteers over the age of 70 years.

INTERVENTION

Power group: high-velocity leg exercises 3 times weekly with weekly increases in resistance combined with 45 minutes of moderate, nonresistance exercise weekly. Walking group: moderate intensity exercise 30 minutes daily, 6 days weekly.

MAIN OUTCOME MEASURES

Variables measured included leg press peak power and leg extensor strength. Functional performance outcomes included: 6-minute walk distance, Short Physical Performance Battery, Physical Performance Test, and Medical Outcomes Study Short-Form Health Survey.

RESULTS

Peak power improved 22% (p =.004) in the power group (3.7 +/- 1.0 W/kg to 4.5 +/- 1.4 W/kg) but did not change in the walking group (3.99 +/-.76 W/kg to 3.65 +/-.94 W/kg). Leg extensor power at resistance of 50%, 60%, and 70% of body weight increased 50%, 77%, and 141%, respectively, in the power group (p <.0001, repeated-measures analysis of variance). Strength improved 22% in the power-trained individuals and 12% in the walkers (p <.0001). Training did not improve functional task performance in either group. One subject developed a radiculopathy during training.

CONCLUSIONS

Resistance training focusing on speed of movement improved leg power and maximal strength substantially, but did not improve functional performance in healthy high-functioning older volunteers.

Preferences for CPR among the elderly: the influence of attitudes and values

OBJECTIVES

While many older individuals wish to forgo cardiopulmonary resuscitation regardless of potential positive outcomes, others desire this intervention despite low chances of survival. This study examines the extent to which health, function, attitudes, and values influence preferences for cardiopulmonary resuscitation.

DESIGN

An in-person, physician-administered survey.

SETTING

Three clinical sites affiliated with a university-based geriatrics program.

PARTICIPANTS

One hundred three individuals age 65 or older with ability to speak, read, and write English.

MEASUREMENTS

Demographic, health and functional status, social involvement, religiosity, attitudes, and values were assessed. A standard description of cardiopulmonary resuscitation was followed by open-ended questions regarding treatment preferences.

RESULTS

Mean age was 81 (+/- 7), 66% were women and 78% had an advance directive. The majority (75%) declined cardiopulmonary resuscitation. Women were more likely to decline cardiopulmonary resuscitation. Attitudes toward life were the strongest predictors for the cardiopulmonary resuscitation decision. Family issues were important, especially the prospect of becoming a burden, as well as the outcome of cardiopulmonary resuscitation.

CONCLUSION

Attitudes toward life, perceived outcome of cardiopulmonary resuscitation, and family issues play a significant role in end-of-life treatment decision-making.

Reliability and responsiveness of two physical performance measures examined in the context of a functional training intervention

BACKGROUND AND PURPOSE

The reliability and responsiveness of 2 physical performance measures were assessed in this nonrandomized, controlled pilot exercise intervention.

SUBJECTS

Forty-five older individuals with mobility impairment (mean age=77.9 years, SD=5.9, range=70-92) were sequentially assigned to participate in an exercise program (intervention group) or to a control group.

METHODS

The intervention group performed exercise 3 times a week for 12 weeks that targeted muscle force, endurance, balance, and flexibility. Outcome measures were the 8-item Physical Performance Test (PPT-8) and the 6-minute walk test. Test-retest reliability and responsiveness indexes were determined for both tests; interrater reliability was measured for the PPT-8.

RESULTS

The intraclass correlation coefficient for interrater reliability for the PPT-8 was. 96. Intraclass correlation coefficients for test-retest reliability were.88 for the PPT-8 and.93 for the 6-minute walk test. The intervention group improved 2.4 points and the control group improved 0.7 point on the PPT-8, as compared with baseline measurements. There was no change in 6-minute walk test distance in the intervention group when compared with the control group. The responsiveness index was.8 for the PPT-8 and.6 for the 6-minute walk test.

CONCLUSION AND DISCUSSION

Measurements for both the PPT-8 and the 6-minute walk test appeared to be highly reliable. The PPT-8 was more responsive than the 6-minute walk test to change in performance expected with this functional training intervention.

Exercise at midlife: how and why to prescribe it for sedentary patients

Moderate exercise for middle-aged and older adults is emerging as an important adjuvant to the treatment of many diseases. These include cardiovascular disease, diabetes, osteoporosis, osteoarthritis, insomnia, deconditioning, and (to a degree) obesity. A recent report from the United States Surgeon General recommends that most adults exercise most if not all days of the week, accumulating 180 minutes of moderate intensity exercise weekly. If your patients have been previously sedentary, encourage them to start a slow, stepwise exercise program. Ongoing support, encouragement, and follow-up can help them commit to and maintain a program of regular exercise.

Step length reductions in advanced age: the role of ankle and hip kinetics

BACKGROUND

Aging is associated with a reduction in gait velocity, which is due to a shortened step length. This study investigated the relationship between joint kinetics and step length.

METHODS

Three-dimensional gait kinematics and kinetics were measured during usual pace gait in 26 older subjects (average age 79) and in 32 young subjects (average age 26). Gait measures were obtained at maximal velocity in five older subjects. Lower extremity strength was measured in the older subjects on an isokinetic dynamometer.

RESULTS

Older persons had a 10% shorter step length during usual gait, when corrected for leg length (.65 +/- .07, .74 +/- .04/leg length, respectively, p < .001). Older persons had reduced ankle plantarflexion during late stance (13 +/- 5 degrees, 17 +/- 5 degrees, p = .02) and lower ankle plantarflexor power (2.9 +/- 0.9 W kg-1, 3.5 +/- 0.9 W kg-1, respectively, p = .007). Ankle strength was associated with plantarflexor power developed during late stance (r = .49, p < .001). When gait kinetics were corrected for step length, the older subjects developed 16% greater hip flexor power during late stance than younger subjects (estimate of effect: .15 W kg-1, p = .002). Older subjects were unable to increase ankle plantarflexor power at maximal pace, but increased hip flexor power 72% (1.1 +/- 0.3 W kg-1 to 1.9 +/- 1.0 W kg-1, p = .02).

CONCLUSIONS

Older subjects had lower ankle plantarflexor power during the late stance phase of gait and appeared to compensate for reductions in plantarflexor power by increasing hip flexor power. Appropriate training of ankle plantarflexor muscles may be important in maintaining step length in advanced age.

The relationship between physical performance measures and independence in instrumental activities of daily living. The FICSIT Group. Frailty and Injury: Cooperative Studies of Intervention Trials

OBJECTIVES

Understanding the relationship between physical capacity and functional status is required to design exercise interventions to maintain independent living. This study assessed the importance of physical performance in maintaining independence in Instrumental Activities of Daily Living (IADL).

DESIGN

A pre-planned meta-analysis of cross-sectional data from six sites of the Frailty and Injury: Cooperative Studies of Intervention Trials (FICSIT). Linear regression was used to estimate the relationship between physical performance and IADL.

PARTICIPANTS

2190 community-dwelling older subjects.

MEASUREMENTS

IADL was the dependent variable; gait velocity, balance function, grip strength and chair rise time were the predictor variables. Age, gender, education, falls self-efficacy, and cognitive status were covariates.

RESULTS

Gait velocity, balance function, and grip strength were independently related to IADL deficits, after correcting for covariates. The linear slopes were relatively steep. For gait, a decrease of 0.1 m s-1 was associated with 0.10 (95% Cl: 0.17, 0.04) increase in IADL deficits, which is equivalent to 1 ADL deficit in 10 subjects. The linear slopes for hand grip and balance were similar or steeper. In the sites where chair stand time was measured, an increase of 1 second in the time to rise was associated with a 0.14 (0.04, 0.24) increase in IADL deficits. The relationships found in the meta-analytic analysis were consistent across sites which enrolled subjects with widely varying levels of physical performance.

CONCLUSION

Simple measures of physical performance were strongly associated with IADL independence after correcting for many previously identified predictors of functional status. The data from this meta-analysis support testing interventions designed to improve physical performance to determine whether improved performance can maintain or improve independence in IADLs.

Effects of age on the biomechanics and physiology of gait

There are significant changes in gait across the life span, but particularly after the age of 70 years. This article reviews the physiology of gait and the motor control challenges during gait. The kinematics (motion) and the kinetics (moment and power) of normal gait of a database of healthy young and older adults are compared. Older subjects generate significantly lower peak ankle plantar flexor power during gait. The clinical significance of the reduction in ankle plantar flexion power is discussed.

Factors affecting sample selection in a randomized trial of balance enhancement: the FICSIT Study

OBJECTIVE

To determine demographic, functional, and health-related factors that may have influenced the selection of older adults for a randomized trial of balance enhancement.

DESIGN

Comparison of participants with nonparticipants at various stages of the recruiting process.

SETTING

Northeastern suburban community.

PARTICIPANTS

Registered voters aged 75 and older (n = 7191).

MEASUREMENTS

Demographic, health-related, functional, balance, gait, and falling characteristics.

RESULTS

The overall participation rate in the randomized trial was 1.5%. Compared with nonparticipants, participants were significantly more likely to be male, married, living with others, living in a house, highly educated, healthy, and physically active.

CONCLUSION

Recruiting older subjects by mail to studies of rigorous interventions can produce significant selection biases that may limit the population to which results can be generalized.

Dynamic balance in older persons: effects of reduced visual and proprioceptive input

BACKGROUND

Understanding the motor and sensory contributions to balance function in older persons is important in order to design effective interventions to prevent falls and loss of mobility. We tested the contributions of visual and proprioceptive input, muscle strength, and age to balance performance in 110 subjects free of clinical evidence of neurologic disease (mean age 80 years).

METHODS

The EquiTest Sensory Organization Test was used to present sequential conditions that altered sensory input in a 2 (tactile/proprioceptive input) x 3 (visual input) design. Center of force and shear force data were recorded from the platform; the primary outcomes were loss of balance (LOB) and anterior-posterior center of force (COF) displacement as a proportion of foot length (COFD).

RESULTS

Subjects had 3.5 +/- 2.7 LOB during testing. Reduction of vision input increased the odds ratio of a LOB 5.7 fold (3.9, 8.4, 95% CI) in unstable surface conditions, but adaptation with repeated trials was substantial. The adjusted odds ratio of a LOB was 0.65 and 0.45 in the second and third trials, respectively, compared to the first. Muscle strength and age were independent predictors of LOB. Gait velocity, single stance balance, and reported difficulty with ambulation, mobility, and instrumental activities of daily living were also associated with LOB.

CONCLUSIONS

Performance on clinical tests of strength, balance, and gait was associated with performance on a challenging balance test which reduced sensory input and effectiveness of motor responses. Adaptation to challenging balance conditions was substantial in this group of older subjects, but was diminished in the oldest subjects.

Functional base of support decreases with age

BACKGROUND

Poor balance in older persons increases the risk of injurious falls during daily activities. Functional base of support (FBOS), the anterior-posterior proportion of foot length used in maximal sustained forward and backward leaning, tests controlled center of mass movement, a component of balance required in daily activities. The purpose of this study was to examine the relationship between FBOS and age and establish the reliability of this measure.

METHODS

Subjects were 113 community-dwelling men and women, ages 20 to 91. FBOS, measured on a force platform, is the difference between mean center of pressure location during sustained forward and backward leaning, divided by foot length. Forward lean (FL), backward lean (BL), and average sway distance during normal standing (STAND SWAY) and while leaning (FBOS SWAY) were also measured.

RESULTS

Mean FBOS was .60 +/- .07 in subjects under age 60, and .42 +/- .12 in subjects 60 and older. FBOS remained constant in younger subjects; beyond age 60, FBOS declined about 16% per decade and was more variable. FL and BL also declined with age, remaining 66% and 34% of FBOS, respectively. STAND SWAY and FBOS SWAY were significantly correlated with each other, but not with FBOS.

CONCLUSIONS

FBOS is a reliable measure and is decreased on average in older persons. This decrease is not related to increased sway while standing or leaning. FBOS is a simple force platform test that has potential as a measure of change in this dimension of balance and as a predictor of falls risk in older persons.

Effects of resistive and balance exercises on isokinetic strength in older persons

OBJECTIVE

To determine the safety and efficacy of 3 months of resistive training of multiple lower extremity muscle groups compared with balance training in persons over 75 years.

DESIGN

Randomized 3-month clinical trial. Subjects (n = 110, mean age 80) were randomized to 4 groups in a 2 x 2 design (control, resistive, balance, combined resistive/balance).

INTERVENTIONS

Resistive training involved knee extension and flexion, hip abduction and extension, and plantar and dorsiflexion using simple resistive machines and sandbags. Balance training consisted of exercises to improve postural control. The control group attended 5 health-related discussion sessions.

MEASUREMENTS

Summed isokinetic moments (N m) of 8 leg movements: hip, knee and ankle flexion/extension, and hip abduction/adduction. Secondary outcomes were gait velocity and chair rise time.

MAIN RESULTS

Summed peak moment increased in both resistive exercise-trained groups (13% increase in the resistive group and 21% in the combined training group, P < 0.001). The effect of resistance training was significant (MANOVA F = 21.1, P < 0.001), but balance training did not improve strength, and there was no interaction (positive or negative) between balance and resistive training. Maximal gait velocity and chair rise time did not improve. Eleven subjects (20%) had musculoskeletal complaints related to resistive training, but all were able to complete the program with modifications.

CONCLUSION

Resistive training using simple equipment is an effective and acceptable method to increase overall leg strength in older persons. Resistive or balance training did not improve maximal gait velocity or chair rise time in this sample of relatively healthy older persons.

Balance improvements in older women: effects of exercise training

BACKGROUND AND PURPOSE

Loss of lower-extremity strength increases the risk of falls in older persons. The purpose of this study was to test the hypothesis that a vigorous program of lower-extremity strengthening, walking, and postural control exercises would improve the single-stance balance of healthy older women and lower their risk of falls and fall-associated injuries.

SUBJECTS

From a total of 38 respondents, 21 women were randomly assigned to either a treatment group (combined training, n = 12) or a control group (flexibility training, n = 9). The subjects ranged in age from 62 to 75 years (mean = 68, SD = 3.5).

METHODS

A randomized control trial compared the effects of two exercise programs on static balance. The combined training group exercised three times per week on knee extension and sitting leg press machines, walked briskly for 20 minutes, and performed postural control exercises, which included simple tai chi movements. The flexibility training group performed postural control exercises weekly. Measurements of balance were obtained on a force platform in double and single stance, at baseline and following 6 months of exercise training.

RESULTS

Double-stance measurements were unchanged after training. The mean displacement of the center of pressure in single stance improved 17% in the combined training group and did not change in the flexibility training group. A repeated-measures analysis of variance revealed that the difference in improvement between the combined training and flexibility training groups was not significant.

DISCUSSION AND CONCLUSION

This is the first intervention trial to demonstrate improvements in single-stance postural sway in older women with exercise training. Additional studies with more subjects will be needed to determine whether a combined training program of resistance training, walking, and postural exercises can improve balance more than a program of postural control exercises alone.

Exercise to improve gait velocity in older persons

The effect of 12 weeks of resistance and balance training on strength and gait measures in older persons was tested in a randomized control trial. Thirty-one residents of two life-care communities volunteered (mean age, 82.1 years). The exercise group (E) trained three times per week, performing resistance training to fatigue for knee extension, hip abduction, ankle dorsiflexion, hip extension, and knee flexion, and postural control exercises. The control group (C) met weekly for flexibility exercises performed sitting in a chair. The exercise group achieved significant improvements in muscle strength and gait velocity (p < .05). Knee extension one maximum repetition increased 32% (24% to 40%, 95% confidence interval [CI]), from 55 +/- to 72 +/- 4N.m. Isokinetic knee extension torque increased 25% (3% to 47%) from 40 +/- 5 to 50 +/- 5N.m at 120 degrees s-1. Usual gait velocity increased 8% (3% to 13%) in E from 1.04 +/- .07 to 1.12 +/- .06m/s. There was a trend of improvement in maximal gait speed 4% (0 to 8%) from 1.43 +/- 0.1 to 1.49 +/- 0.1m/s, p = 0.054. Gait and strength measures in C were unchanged. A short-term exercise program that trained strength and balance achieved a clinically significant improvement in gait velocity.