Journal of Gerontology: MEDICAL SCIENCES
2002, Vol. 57A, No. 1, M26–M36
Copyright 2002 by The Gerontological Society of America
Effects of Moderate-Intensity Exercise on
Physiological, Behavioral, and Emotional Responses
to Family Caregiving: A Randomized Controlled Trial
Abby C. King,1,3 Kellie Baumann,2 Paula O’Sullivan,3 Sara Wilcox,4 and Cynthia Castro3
1Division of Epidemiology, Department of Health Research and Policy, 2Center for Research on Women’s Health and
Reproductive Medicine, Department of Obstetrics and Gynecology, and 3Stanford Center for Research in Disease Prevention,
Department of Medicine, Stanford University School of Medicine, Palo Alto, California.
4Department of Exercise Science, School of Public Health, University of South Carolina, Columbia.
Background. The study objective was to determine the health and quality-of-life effects of moderate-intensity exercise among older women family caregivers.
Methods. This 12-month randomized controlled trial involved a volunteer sample of 100 women aged 49 to 82 years
who were sedentary, free of cardiovascular disease, and caring for a relative with dementia. Participants were randomized to 12 months of home-based, telephone-supervised, moderate-intensity exercise training or to an attention-control
(nutrition education) program. Exercise consisted of four 30- to 40-minute endurance exercise sessions (brisk walking)
prescribed per week at 60% to 75% of heart rate reserve based on peak treadmill exercise heart rate. Main outcomes
were stress-induced cardiovascular reactivity levels, rated sleep quality, and reported psychological distress.
Results. Compared with nutrition participants (NU), exercise participants (EX) showed significant improvements in
the following: total energy expenditure (baseline and post-test means [SD] for EX 1.4 [1.9] and 2.2 [2.2] kcal/kg/day;
for NU 1.2 [1.7] and 1.2 [1.6] kcal/kg/day; p .02); stress-induced blood pressure reactivity (baseline and post-test
systolic blood pressure reactivity values for EX 21.6 [12.3] and 12.4 [11.2] mm Hg; for NU 17.9 [10.2] and 17.7
[13.8] mm Hg; p .024); and sleep quality ( p .05). NU showed significant improvements in percentages of total calories from fats and saturated fats relative to EX ( p values .01). Both groups reported improvements in psychological
distress.
Conclusions. Family caregivers can benefit from initiating a regular moderate-intensity exercise program in terms of
reductions in stress-induced cardiovascular reactivity and improvements in rated sleep quality.
D
URING the upcoming decades, the burden and cost of
providing care to an ill or disabled relative will touch
nearly every U.S. household (1). The potentially devastating
physical and emotional impact of caregiving was recently
underscored by the Caregiver Health Effects Study, in
which family caregiving accompanied by emotional strain
was an independent risk factor for mortality among older
adults (2). Data from this study and others have shown that
caregivers are less likely than same-aged peers to engage in
preventive health behaviors that are important for chronic
disease prevention and control, including regular physical
activity (3–7). Regular physical activity of even moderate
intensity decreases cardiovascular disease risk in younger
and older adults alike (7–9) and can positively impact quality-of-life outcomes, such as stress responses, depressive
symptoms, and sleep quality, which are of particular relevance to older caregivers (10–14).
Despite the many benefits of regular moderate-intensity
physical activity, less than 25% of middle- and older-aged
adults, including older family caregivers, are regularly active enough to achieve these benefits (6,7). The majority
of physical activity programs for middle- and older-aged
adults occur in community-based settings, which can pose
significant challenges for caregivers, who often face subM26
stantial time and logistical constraints (6,15). Telephonesupervised, home-based, physical activity regimens are effective alternatives to group-based regimens and provide a
promising strategy for increasing physical activity in the
caregiving population (16).
The current study represents the first systematic investigation of the effectiveness of a physical activity intervention
tailored to the challenges and needs of family caregivers. We
investigated the following hypotheses: (i) The home-based
physical activity intervention would result in significantly
greater 1-year increases in physical activity levels relative to
an attention-control (nutrition education) condition. (ii) Caregivers randomly assigned to the physical activity intervention would demonstrate significantly reduced cardiovascular
reactivity levels at 1 year in response to an emotional challenge relative to controls. Such reactivity represents one potential pathway mediating the relationship between physical
inactivity and negative cardiovascular outcomes (17–20).
Notably, blood pressure elevations related to the caregiving
situation have been reported in at least one study comparing
women caregivers with noncaregivers (11). (iii) Caregivers randomly assigned to the physical activity intervention
would report significantly enhanced quality-of-life outcomes
relative to controls. Psychological distress and rated sleep
EXERCISE INTERVENTION WITH FAMILY CAREGIVERS
quality were selected due to their particular relevance to
older caregivers (21,22), and also because the literature indicates positive physical activity–related impacts on these outcomes (10,13). In addition, we predicted that caregivers randomly assigned to the nutrition education condition would
show better dietary patterns at 1 year relative to caregivers
assigned to the physical activity intervention. Healthful dietary patterns represent an additional important health behavior domain strongly linked to premature morbidity and
mortality (23,24). We targeted older women caregivers of
relatives with dementia in light of this increasingly prevalent
and challenging caregiving circumstance, undertaken primarily by older women (21,25,26).
METHODS
Participants
Participants were 100 women (47 adult children caregivers and 53 spousal caregivers) who had enrolled in the
Teaching Healthy Lifestyles for Caregivers study. Eligibility
criteria for the major trial were as follows: postmenopausal;
50 years of age or older (could be 46–49 years if participant
was postmenopausal due to a complete hysterectomy); a
woman caregiver (defined as providing care in one’s home
for a relative with Alzheimer’s disease or another form of
dementia, as documented by the care recipient’s physician);
providing at least 10 hours of unpaid care per week; not
planning to move from the area during the next year; free
from any medical conditions that would limit participation in
moderate-intensity exercise (e.g., walking); not participating
in a regular program of physical activity (i.e., less than three
times per week of exercise lasting 20 minutes per session
over the past 6 months); and stable on all medications for at
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least 3 months prior to study entry. Recruitment occurred via
community-wide promotion, including use of an array of
media sources as well as referrals from physicians and organizations serving older adults and caregivers. A summary of
enrollment patterns is shown in Figure 1.
Procedures
During the 1-week period prior to randomization and
following the attainment of informed consent, participants
underwent medical, physical, and psychosocial assessment
(repeated at 1 year). The assessment included an electrocardiogram- (ECG-) monitored, symptom-limited, graded treadmill exercise test using a Balke-type protocol with workloads
increasing by approximately 1.0 to 2.0 metabolic equivalents
every 2 minutes (27). Individuals with baseline evidence of
exercise-induced ischemia, determined by physician review
of the ECG, were excluded from study participation. Three
individuals were excluded because of a positive treadmill
test. Following baseline evaluation and stratification by relationship to care recipient (i.e., spouse vs other) and care recipient dementia diagnosis (Alzheimer’s disease vs other
forms of dementia), participants were randomly assigned to
one of two conditions using a computerized version of the
Efron procedure (28): (i) a 12-month moderate-intensity endurance exercise training program or (ii) a 12-month attention control (nutrition education) condition. Nutrition education has been found to provide an effective control for staff
attention and participant expectancy effects when evaluating
physical activity–related outcomes (29,30).
Physical activity condition.—Each participant randomly
assigned to the exercise training program was provided an
exercise prescription in which exercise intensity was gradu-
Figure 1. Progress through the various stages of the trial, including flow of participants, withdrawals, and timing of the outcome measures.
The “R” indicates randomization.
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KING ET AL.
ally increased over the initial 6-week period to 40% to 59%
of heart rate reserve based on the peak heart rate achieved
during symptom-limited treadmill testing (31).
Participants were instructed to engage in at least four
30- to 40-minute exercise sessions per week of primarily
brisk walking, in a home-based format, throughout the 12month period. Participants were also encouraged to increase
other forms of routine activity throughout the day, such as
leisurely walking and gardening.
During a 30- to 40-minute introductory session, following randomization, a project health educator provided instruction on the exercise program to be initiated. Each participant worked with the health educator to develop an
individualized physical activity plan based specifically on
her physical activity preferences and particular caregiving
situation. The majority of participants randomized to exercise chose to engage in brisk walking in their immediate
neighborhoods (76%). For the 12 participants who could not
leave or find coverage for their care recipient for 30 minutes
during the day, an indoor activity program was developed
based on the participant’s preferences. Indoor programs included stationary cycling or use of project-provided exercise videotapes. Participants were instructed in how to take
their heart rates and monitor their perceived exertion during
exercise using the Borg scale (32). They recorded this information on activity logs, which were used by the health educators to counsel them on how to increase their exercise
frequency, intensity (e.g., pace), and duration. Written information was provided, and the staff member telephoned
the participant at home the following week to check on
progress. Telephone contact, beginning the week following
randomization, occurred on a biweekly basis during the first
2 months, and then once monthly through 12 months (for a
total of 14 calls throughout the intervention period). Telephone contacts, which lasted an average of 15 to 20 minutes, were used to monitor progress, answer questions, and
provide individualized feedback. Participants completed
brief daily logs to record home-based physical activities, including activity type, intensity, and duration, which were
mailed back to the project staff monthly.
Attention-control (nutrition education) condition.—
Participants randomized to this condition received a telephone-based nutrition education program that was matched
with the physical activity program on the amount and type
of staff contact received (introductory session describing
the nutrition program and 14 telephone contacts). The nutrition program was based on recommendations from the
American Heart Association, and similar organizations, for
a heart-healthy diet (33). National dietary recommendations
aimed at reducing the total percentage of calories from fat to
less than 30% were used along with dietary guidelines
aimed at increasing fruit and vegetable intake (34). Participants completed brief daily nutrition logs, which were
mailed back to the project staff monthly. During each month
of the intervention period, a different nutrition topic was targeted for monitoring and intervention (e.g., high-fat snack,
fruit, and vegetable intake). Participants were given homework assignments to complete specific to each topic (e.g.,
trying certain recipes and label-reading assignments).
For both conditions, health educators utilized behavioral
strategies based on social cognitive theory to enhance behavioral adherence (35). These included discussion of the benefits associated with behavior change, specific goal-setting,
regular self-monitoring and feedback, topic-specific educational materials, and relapse prevention training (35,36).
Measurement Procedures
Demographics.—Participants completed a measure of
demographic characteristics, including their age (in years),
marital status, ethnicity, education (in years), and employment status (22). They were asked to note the number of
prescribed medications that they were currently taking, as
well as the number and type of chronic conditions. They
also rated their health on a 5-point Likert scale taken from
the Medical Outcomes Study Short-Form General Health
Survey (37). Participants were asked, “In general, would
you say your health is excellent [5 points], very good [4
points], good [3 points], fair [2 points], or poor [1 point]?”
Caregiving characteristics.—Participants completed a
survey focused on different aspects of their caregiving experience (6). Items included their familial relationship to the
care recipient, age and diagnosis of the care recipient (confirmed by the care recipient’s physician), length of time as a
caregiver, and average hours per week spent caregiving.
Caregiver burden was assessed for descriptive purposes
with the 25-item Screen for Caregiver Burden (38–40). Average scores for family caregivers on this scale typically
have been reported to be between 9 and 11 for objective burden and between 35 and 37 for subjective burden (38,41).
The level of behavioral problems evidenced by participants’ care recipients was measured using the Revised
Memory and Behavior Problems Checklist (RMBPC), a 24item caregiver-report measure of observable behavioral
problems in dementia patients (42). The caregiver’s perception of such behavioral problems has been found to be a
stronger predictor of caregiver burden, institutionalization,
and related factors than other care recipient factors, such as
cognitive impairment or functional limitations (43). The
measure provides one total score and three subscale scores
for patient problems (memory-related, depression, and disruptive behaviors) and parallel scores for caregiver reaction
(42). The RMBPC has been found to be a valid and reliable
instrument for assessing behavior problems in dementia patients (42). The average frequency score for the total scale
has been reported to be 34 (possible range, 1–87). The average reaction score for the total has been reported to be 23
(possible range, 0–77) (42).
Assessment of exercise adherence.—Average monthly adherence rates across the 12-month period were calculated for
subjects randomized to the physical activity condition as
follows: number of exercise sessions reported (based on activity logs described earlier) as a percentage of exercise sessions prescribed for the month.
Approximately 20% of participants were randomly selected to wear a solid-state two-channel portable microprocessor (Mini-Logger Series 2000, Mini Mitter Company,
EXERCISE INTERVENTION WITH FAMILY CAREGIVERS
Inc, Sunriver, OR), which recorded heart rate and body
movement continuously throughout the day for up to a 3-day
period during the course of the study. This and similar solidstate portable microprocessors provide a valid and reliable
indicator of adherence to prescribed exercise (44–46).
Physical activity assessment.—To assess change in physical activity levels, participants completed the Community
Health Activity Model Program for Seniors (CHAMPS)
physical activity questionnaire for seniors (47,48). This 47item self-report instrument, which summarizes frequency
and duration of a range of activities undertaken during the
previous month, has been found to provide a valid and reliable estimate of energy expenditure in older adults (47,48)
and is sensitive to change in response to moderate-intensity
physical activity interventions (31,47,48).
Cardiovascular reactivity to emotional challenge.—
Caregivers underwent a laboratory-based emotional challenge to evaluate levels of cardiovascular reactivity. Participants were instructed to refrain from caffeine intake or
physical exercise the morning of the emotional challenge.
The protocol began with a 10-minute rest period during
which time the participant sat alone quietly in a room and
listened to relaxing music via headphones (baseline). Following that period, a trained research assistant engaged the
participant in 2 minutes of neutral conversation and then directed the participant to speak for about 6 minutes about the
aspects of her caregiving experience that she found to be
most frustrating or disturbing. The research assistant made
minimal verbal responses during the task period. Following
the 6-minute task period, the research assistant left the room,
and the participant rested for an additional 10 minutes (the
recovery period). Heart rate and blood pressure recordings
were collected every 2 minutes from the beginning of the
baseline period through the recovery period through use of a
Colin ambulatory blood pressure monitor (model ABPM630, Colin Medical Instruments, Plainfield, NJ) attached to
the nondominant arm. The recordings were averaged within
each portion of the emotional challenge (i.e., baseline, task,
and recovery) to obtain mean heart rate, systolic blood pressure, and diastolic blood pressure levels. Reactivity levels
were obtained by subtracting the mean baseline from mean
task levels for each hemodynamic variable. Speaking tasks
involving emotionally relevant content have been shown to
provide a reliable means of eliciting elevations in hemodynamic variables in a variety of populations of women (49),
including caregivers (50).
Rated sleep quality.—The 19-item Pittsburgh Sleep Quality Index (PSQI) was used to evaluate self-rated sleep quality at baseline and at 1 year (51). This questionnaire assesses sleep quality and disturbances over a 1-month time
interval and generates seven “component” scores. Three
components found in previous research with older adults to
be sensitive to change with moderate-intensity physical activity were of interest (13): subjective sleep quality (possible subscale score, 0–3), sleep latency (i.e., average time in
minutes needed to fall asleep), and sleep duration (i.e., average number of hours of actual sleep per night). An average
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score on the sleep quality subscale for a sample of healthy
middle- to older-aged adults without sleep complaints has
been reported to be 0.35 (lower scores on this scale indicate
better sleep) (22,51). Middle- and older-aged adults in the
general population typically report a sleep duration of between 7 and 8 hours per night and a sleep latency of less
than 20 minutes (52,53).
Rated psychological distress.—The psychological distress domain included measures of rated stress and depressive symptoms. Rated stress was measured using the
Perceived Stress Scale (PSS) (54), a 14-item scale that measures the degree to which situations in one’s life are appraised as stressful. The PSS has been found to have adequate internal and test-retest reliability and is positively
correlated with a variety of self-report and behavioral indices of stress in adult populations (54,55). Average scores on
this scale for healthy adult noncaregiving populations typically range from 17 to 25 (10,54,56). The average score in a
study of older women caregivers was reported to be 29 (6).
Depressive symptoms were measured using the Beck Depression Inventory (BDI) (57), a valid and reliable 21-item
inventory that has been used extensively to measure depression and distress in a variety of populations (58,59). Average scores for nondepressed groups of middle- and olderaged adults typically are less than or equal to 6 (10,56).
Dietary assessment.—Participants completed the Block95
Food Frequency questionnaire, 1995 version, which is a revised version of the Health Habits and History questionnaire (60,61). Participants self-report the average frequency
of consumption of 90 foods and average serving sizes over
the past year. The correlations between versions of this
questionnaire and 4-day dietary records ranged from 0.42 to
0.71 (60,61). The National Cancer Institute’s DIETSYS
program was used to derive estimates of dietary nutrients
and frequency of various food groups (62). Based on the nutrition intervention, dietary components specifically targeted by the assessment were the percentage of calories derived from total fats and saturated fats, the intake of high-fat
snacks and sweets, and fruit and vegetable intake.
A food frequency questionnaire was chosen rather than
alternative instruments (e.g., dietary records or repeat 24hour dietary recalls), due to subject burden and cost issues.
The Block95 Food Frequency questionnaire was used in
light of its inclusion of food items particularly germane to
individuals living in the western United States.
Statistical Analyses
Analysis of covariance (ANCOVA) was used to assess
changes during the 1-year period in the variables of interest
(general linear model) (63). The main effects for group assignment were evaluated, with baseline levels of the dependent variable and relation to care recipient (spouse vs other)
and care recipient diagnosis (Alzheimer’s disease vs other)
serving as covariates. Two-way interactions between group
assignment and the latter two covariates were also evaluated. These interactions were undertaken in light of the potential differences in caregiver–care recipient relationship
factors, as well as in dementia time course, which could in-
M30
KING ET AL.
fluence caregiver burden and, consequently, intervention
outcomes. The least-squares means method was used to
compare group means for all significant effects (64). For the
psychological distress domain and rated sleep domain in
which several measures or subscales were collected, a multivariate ANCOVA (MANCOVA) was first used as an omnibus test incorporating the relevant scales. Following a statistically significant MANCOVA, ANCOVA procedures
were conducted for each measure or subscale. The level
for all tests was set at .05. A one-tailed test of significance
was applied for tests of major hypotheses in light of the directional nature of the posited hypotheses (65,66). For other
descriptive analyses, two-tailed tests of significance were
applied.
RESULTS
Subjects
Fifty-one caregivers were randomized to the physical activity condition and 49 to the nutrition control condition. A
description of the study sample is shown in Table 1. Caregivers were an average of 63 years old (range, 49–82 years).
Of these, 86% were white. Participants were living with
their care recipients either all (92%) or most (8%) of the
time throughout the week. They had spent an average of 4
years caring for their impaired relative, 63% of whom had
received a diagnosis of Alzheimer’s disease. The mean age
of the care recipients was 80 years. Caregivers reported
spending an average of 72 hours per week undertaking caregiving duties. These caregiving characteristics are similar to
those of samples of caregivers studied previously (6). As
expected, the levels of psychological distress observed in
this sample (shown in Table 1) are higher than typically observed in similarly aged noncaregiving samples (10,22). For
example, the mean baseline BDI score places this sample in
the mild depression category (scores of 10–15) on that clinical measure (67), which is similar to other samples of caregivers reported in the literature (6,38,68). This mean score
is twice that found in comparably aged samples of noncaregiving women living in the same locale (10). In addition,
the sample’s scores on the PSS averaged 10 points (i.e., 1
SD) higher than scores found in comparably aged samples
of noncaregiving women living in the same locale (10).
In evaluating the descriptive data at baseline, caregivers
randomized to the nutrition program had somewhat higher
initial levels of depressed affect and subjective burden, and
a somewhat smaller percentage were currently employed.
Exploratory analyses of covariance evaluating the interaction between these baseline variables and group assignment
indicated no differential impacts of these small baseline differences on any of the outcomes of interest.
Information collected about care recipient functioning via
the RMBPC is shown in Table 1. The means for the total
and subscale scores were quite similar to those reported in
the literature (42). The two conditions were comparable on
this measure at baseline and at 12 months, with both groups
showing modest (nonsignificant) changes in this measure
across the year. Changes in this scale across the year were
not significantly correlated with changes in either the physical activity or dietary measures (Spearman correlation coef-
Table 1. Descriptive Statistics† at Baseline and 12 Months for
Variables of Interest, by Condition Assignment
Variable
Physical
Activity
Nutrition
Education
Control
90%
Confidence
Intervals‡
n
45
40
—
Age, y
62.2 (9.3)
63.3 (9.0)
—
Education, y
15.4 (2.2)
14.6 (2.8)
—
Currently employed, %
37.7
27.5
—
Wife caregiver, %
55.6
50.0
—
Alzheimer’s care recipient
diagnosis, %
64.7
63.3
—
Antihypertensive medication use, % 27.5
30.6
—
27.8 (4.8)
26.9 (5.6)
—
Body mass index, kg/m2
At 12 mo
27.9 (5.2)
26.9 (5.3)
—
Resting systolic BP, clinic
117.3 (13.8) 123.2 (14.0)
—
At 12 mo
118.0 (15.2) 121.6 (15.0)
—
Resting diastolic BP, clinic
69.6 (6.7)
68.0 (7.4)
—
At 12 mo
68.8 (8.6)
66.5 (9.3)
—
Objective burden score
11.5 (3.7)
12.6 (4.0)
—
At 12 mo
10.8 (3.6)
11.8 (4.8)
—
Subjective burden score
39.6 (9.4)
43.7 (9.8)
—
At 12 mo
35.7 (7.5)
40.9 (12.8)
—
Revised memory and behavior
problems checklist
Total frequency ratings score
39.9 (12.7) 39.1 (14.3)
—
At 12 mo
39.7 (15.3) 39.9 (15.4)
—
Frequency, memory problems
19.8 (4.2)
20.4 (6.3)
—
At 12 mo
23.9 (7.8)
23.3 (5.4)
—
Frequency, depressive
symptoms
12.6 (7.3)
11.3 (7.8)
—
At 12 mo
10.4 (7.2)
9.5 (7.0)
—
Frequency, disruptive
behaviors
7.5 (5.8)
8.3 (5.7)
—
At 12 mo
6.4 (4.0)
7.1 (5.8)
—
Total reaction ratings score
24.6 (15.4) 25.5 (10.3)
—
At 12 mo
23.6 (15.4) 23.0 (12.1)
—
Reaction, memory problems
11.4 (5.6)
10.3 (4.5)
—
At 12 mo
9.1 (6.4)
9.2 (4.7)
—
Reaction, depressive
symptoms
10.3 (7.9)
7.3 (5.2)
—
At 12 mo
9.6 (7.5)
7.3 (6.2)
—
Reaction, disruptive behaviors
9.5 (7.2)
8.0 (5.7)
—
At 12 mo
6.0 (4.2)
6.5 (5.6)
—
Outcomes of Interest
Physical activity
Total energy expenditure,
kcal/kg/d
1.4 (1.9)
1.2 (1.7)
At 12 mo**
2.2 (2.2)
1.2 (1.6)
1.1 to 2.6
Total time spent in all
3.1 (3.8)
2.8 (3.6)
physical activity, h/wk§
At 12 mo**
5.0 (4.9)
2.9 (3.7)
1.2 to 3.6
Cardiovascular reactivity
Systolic BP reactivity,
mm hg
21.6 (12.3) 17.9 (10.2)
At 12 mo**
12.4 (11.2) 17.7 (13.8) 11.6 to 1.1
Diastolic BP reactivity,
mm hg
10.6 (6.6)
10.5 (5.4)
5.5 to 1.3
At 12 mo**
6.6 (5.4)
9.6 (7.1)
Heart rate reactivity,
beats/min
7.6 (4.9)
6.8 (5.2)
3.5 to 0.2
At 12 mo
6.1 (4.6)
7.2 (5.1)
Continued on next page
EXERCISE INTERVENTION WITH FAMILY CAREGIVERS
Table 1. Descriptive Statistics† at Baseline and 12 Months for
Variables of Interest, by Condition Assignment (Continued)
Variables
Sleep quality
Rated sleep quality
subscale score
At 12 mo*
Sleep duration, h/night
At 12 mo
Sleep latency, min to fall
asleep
At 12 mo
Psychological distress
Beck Depression
Inventory score
At 12 mo
Perceived stress scale
score
At 12 mo
Reported dietary intake
Total calories from fat, %
At 12 mo***
Total calories from
saturated fat, %
At 12 mo***
Fat/oils/sweets/snacks,
frequency/d
At 12 mo***
Vegetables, frequency/d
At 12 mo
Fruits, frequency/d
At 12 mo
Physical
Activity
Nutrition
Education
Control
1.1 (0.8)
0.9 (0.8)
6.6 (1.0)
5.5 (2.9)
1.1 (0.6)
1.2 (0.8)
6.6 (1.3)
6.2 (2.1)
90%
Confidence
Intervals‡
0.6 to 0.1
1.7 to 0.3
22.0 (23.8)
20.9 (23.3)
29.8 (39.4)
29.7 (32.1) 10.4 to 4.7
10.7 (6.5)
7.4 (4.8)
13.7 (6.3)
9.4 (7.2)
0.1 to 3.6
28.1 (8.3)
24.8 (8.1)
29.3 (6.8)
26.6 (8.5)
2.6 to 2.9
31.6 (5.7)
31.8 (6.3)
33.3 (6.9)
29.6 (8.3)
1.1 to 6.0
10.2 (2.3)
10.3 (2.2)
10.9 (2.7)
9.5 (2.9)
1.5 to 3.2
2.7 (2.0)
2.3 (1.3)
2.7 (0.9)
2.7 (1.2)
2.0 (1.1)
2.1 (1.3)
2.2 (1.4)
1.5 (1.2)
2.6 (1.1)
2.8 (1.1)
1.6 (0.9)
2.1 (1.0)
1.2 to 2.3
0.5 to 0.2
0.6 to 0.1
Note: BF blood pressure.
†Means (SD), frequencies.
‡Confidence intervals for outcomes of interest represent a measure of precision for the mean 12-mo difference between treatment and control conditions, adjusted for baseline value, relation to care recipient, and care recipient diagnosis.
§Includes light, moderate, and vigorous forms of physical activity.
For the sleep quality subscale, a decrease represents improvement.
*Physical activity condition different from nutrition condition at p .05.
**Physical activity condition different from nutrition condition at p .03.
***Physical activity condition different from nutrition condition at p .01.
ficients .30). This suggests that the targeted interventions
were able to promote changes in these health behaviors
across the year, irrespective of any changes that were occurring in care recipient behaviors during that period.
Fourteen caregivers experienced the institutionalization
or death of their care recipient during the study (comparable
numbers in each condition), with the majority of these incidences occurring toward the end of the 1-year intervention.
Individuals continued to receive exercise or nutrition counseling as indicated by their condition assignment. There
were no significant differences between this subgroup and
the rest of the sample with respect to either physical activity
or dietary behaviors at the end of the intervention.
The total energy expended by the sample in all forms of
physical activity at baseline averaged less than 100 kcal per
day, an amount that is less than current nationally recommended goals for physical activity (7). In addition, the sample spent an average of 85 minutes per week in activities of
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at least moderate intensity, in contrast to the surgeon general’s recommendations to spend at least 150 minutes per
week in such activities (7). Participants’ baseline V̇O2max
levels averaged 22.4 3.9 ml/kg/minute, which reflects fitness levels comparable to other similarly aged populations
of women not engaged regularly in vigorous forms of activity (7,36).
With respect to general health status, the mean score on
the self-rated health question was 3.3 (range, 1–5), which
places the sample in the “good” category (percentage
choosing “poor” 1.1%, “fair” 12.5%, “good” 48.6%, “very good” 31.8%, and “excellent” 6.0%).
The average number of chronic conditions reported by caregivers was 1.1 (range, 0–4). The most prevalent conditions
were arthritis (36% of the sample), hypertension (29%), and
chronic pulmonary disease (14%). Participants were taking
an average of 1.9 prescribed medications per day (range,
0–6). Eighty percent of the women in both conditions were
taking at least one medication daily. The most common
medications were hormone replacement therapy (HRT; n 47), antihypertensives (n 29), and thyroid medication (n 19). The two conditions were comparable on these health
factors at baseline.
The 12-month data were collected on 85% of the sample
(comparable percentages by study condition, relationship to
care recipient, and type of dementia diagnosis). Participants
who contributed 12-month data (n 85) were comparable
to those who did not (n 15) on all but three baseline variables of interest ( p values .02): Those lacking 12-month
data reported more baseline hours per week spent in caregiving duties (mean, 100.5 41.7 vs 66.2 45.4 hours)
and were significantly more depressed (mean score, 16.2 8.2 vs 11.6 6.1) and stressed (mean score, 33.5 4.8 vs
27.9 7.7) at baseline relative to those who returned at 12
months. Changes on the outcomes of interest for each condition are presented in Table 1.
Exercise Adherence
Among participants randomized to the physical activity
condition, adherence to the exercise prescription across the
12-month period averaged 73.4% 31% of prescribed exercise sessions completed (range, 9%–150%), with an average reported duration of 35.8 23.0 minutes per session.
This level of physical activity adherence is similar to that
obtained in noncaregiving groups of older adults using telephone-supervised home-based formats (16). The increase in
physical activity among subjects in the exercise condition
was reflected in the ambulatory heart rate and activity recording data. For the 9 exercise subjects randomly selected
to wear the 3-day ambulatory heart rate and activity monitor, there was an 87.5% agreement rate between continuous
bouts of physical activity within the moderate-intensity target heart rate range as recorded by the monitor as well as on
the participants’ logs. In addition, 2 of the participants reported physical activity bouts of sufficiently long duration,
but which failed to reach the targeted exercise heart rate
range. The exercise session duration in the prescribed heart
rate range as measured by the heart rate and activity monitor
averaged 32.8 20.3 minutes.
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KING ET AL.
Change in Physical Activity Levels
As hypothesized, caregivers assigned to the physical activity condition reported a significantly greater total daily
energy expenditure at 12 months (baseline-adjusted 12month mean, 2.1 kcal/kg/day) relative to caregivers assigned
to nutrition (adjusted mean, 1.3 kcal/kg/day; F[6,77] 4.1,
p .02). This translated into an adjusted mean of 5.0 hours
per week in all forms of physical activity for those in the
physical activity condition (adjusted mean, 2.9 hours/week
for nutrition condition; F[6,77] 4.8, p .02). Approximately half of those 5 hours (adjusted mean, 2.4) came from
moderate-intensity activities (primarily brisk walking), with
the other half (adjusted mean, 2.6) spent in more routine
forms of lighter activity, such as leisurely walking and gardening. For the average-weight participant in this study
(mean body weight, 74 kg), this amount of daily energy expenditure translates into approximately 1088 kcal/week expended in physical activity among physical activity participants.
There were no changes in fitness levels based on treadmill testing as a consequence of this moderate-intensity
physical activity program (69). Neither were there changes
in resting blood pressure levels in this initially normotensive sample of women.
Change in Cardiovascular Reactivity in Response to an
Emotional Challenge
As hypothesized, caregivers assigned to physical activity
showed significantly lower 12-month systolic and diastolic
blood pressure reactivity levels in response to the emotional
challenge relative to nutrition controls (p values .03).
These results are shown in Figure 2. No significant between-group differences were found for 12-month heart rate
reactivity, or during the baseline or recovery periods for the
three variables.
Two ANCOVAs were also undertaken to evaluate the effects of antihypertensive medication and HRT use, and their
Figure 2. Twelve-month reductions in stress-induced systolic and
diastolic blood pressure (BP) reactivity levels, by condition (means,
SE; conditions significantly different at post-test, *p .05).
interactions with condition assignment, on blood pressure
and heart rate reactivity. The results were identical to those
reported previously, with none of the antihypertensive medication or HRT effects achieving statistical significance (p
values .10). (Approximately 47% of participants in each
condition were on HRT.)
Change in Rated Sleep Quality
The MANCOVA evaluating the overall 12-month between-group differences in the three sleep variables was
significant (F[3,68] 2.4, p .039). Rated sleep quality
was significantly better at 12 months in the exercise condition (adjusted mean score, 0.87) relative to the nutrition
condition (adjusted mean score, 1.2; F[6,74] 2.9, p .045). (Note that a lower score on this subscale denotes better sleep quality.) Among exercisers, improvement in rated
sleep quality was significantly associated with 12-month reductions in perceived stress (Spearman rank r .33) and
subjective caregiver burden (r .33; p values .04). There
were no significant group differences in either the sleep duration or sleep latency variables (see Table 1).
Change in Psychological Distress
The MANCOVA evaluating the overall 12-month between-group differences on the PSS and the BDI did not
reach statistical significance. Within-group paired comparison t-test analyses, undertaken for descriptive purposes, indicated that both groups improved over the 12-month period
on these two psychological outcomes (p values .05; see
Table 1).
Change in Dietary Patterns
As hypothesized, caregivers assigned to the nutrition condition reported a significantly lower percentage of total calories from fat at 12 months (baseline-adjusted 12-month mean,
29.1%) relative to caregivers assigned to the physical activity condition (baseline-adjusted mean, 32.6%; F[6,68] 5.3, p .01). They also reported a lower percentage of calories from saturated fats at 12 months (baseline-adjusted
12-month mean, 9.3%) relative to exercisers (baselineadjusted mean, 10.6%; F[6,68] 7.5, p .004). Similarly,
caregivers assigned to the nutrition condition reported a significantly lower daily intake of fats, oils, sweets, and highfat snacks (baseline-adjusted mean, 1.6 servings/day) relative to exercisers (baseline-adjusted mean, 2.2 servings/day;
F[6,68] 5.5, p .01). For both conditions, there were relatively modest changes in average daily total caloric intake
across the year (baseline and 1-year means for exercise condition: 1756.5 520.5 and 1699.0 604.7 kcal, withingroup difference not significant; baseline and 1-year means
for nutrition condition: 1700.2 656.5 and 1432.4 411.2
kcal, within-group difference significant at p .03; no significant differences were found between conditions). Such
modest changes typically are insufficient, either alone or in
combination with a moderate-intensity walking program, to
promote significant weight loss in middle- and older-aged
women without specific, sustained efforts to restrict caloric
intake (7,70,71). It should be noted that weight loss was not
a goal of either of the interventions. Related to this point,
the measures of self-reported dietary and physical activity
EXERCISE INTERVENTION WITH FAMILY CAREGIVERS
behaviors used in this study, while appropriate for evaluating relative changes in behavioral patterns over time, lack
the high level of precision required for evaluating specific
contributions to energy balance (61,72).
A significant interaction effect was found for daily vegetable intake at 12 months (F[6,68] 5.2, p .01). Daughters assigned to nutrition evidenced greater vegetable intake
(adjusted mean, 3.1 servings/day) than daughters assigned
to physical activity (adjusted mean, 2.4, p for pairwise comparison .04). No significant effects were found for 12month fruit consumption.
Exercise-related Injuries
Exercise-related injuries (reported at assessments, on logs,
and during the telephone contacts) were minimal (reported
by 10% of subjects), and none were severe enough to require study termination. The most frequent exercise-related
symptoms (constituting approximately three fourths of those
reported) were muscle soreness and minor pain around the
joints, and these were quickly resolved with an adjustment of
the exercise program and instructions for self-care.
DISCUSSION
To our knowledge, this is the first study to show that interventions tailored to the situational constraints of caregiving result in significant, sustained improvements in health
behaviors critical to caregiver health and functioning (5).
Wife and daughter caregivers assigned to the moderateintensity home-based physical activity program showed significant increases in physical activity–related energy expenditure, averaging over 1000 kcal per week at 12 months, relative to those assigned to the attention-control (nutrition)
condition. This amount of weekly physical activity is commensurate with the amount currently being recommended
for middle- and older-aged adults to achieve important
health and functioning benefits (7,73). The amount of physical activity achieved was sufficient to result in significant
12-month reductions in stress-induced blood pressure reactivity among those assigned to physical activity relative to
controls. Stress-induced cardiovascular reactivity has been
postulated as one potential pathway mediating the relationship between chronic stress and cardiovascular outcomes
(20,74,75). The physical activity–associated decreases in
blood pressure reactivity levels observed, which may reflect
a down-regulation of sympathetic activity (20), were substantial relative to other studies in this area (19,75). Caregivers assigned to the physical activity condition also reported significant 12-month improvements in rated sleep
quality relative to controls. This is notable given that, although family caregivers as a group tend to suffer from poor
sleep (22), the subjects in this study were not selected based
on their level of sleep complaints. This made it potentially
more difficult to detect sleep quality improvements across
this subject sample (13). These results add to the small body
of literature indicating improvements in self-rated sleep
among older adults with the introduction of a moderateintensity home-based physical activity program (13).
Although there were no appreciable increases in fitness
as measured by the treadmill exercise test, a growing
amount of evidence in this area has shown that this is to be
M33
expected when the exercise stimulus is of a more moderate
intensity, such as walking, and the target group is of older
age (69). An increasing number of studies are now available
demonstrating that older adults can achieve significant
health benefits from these more moderate levels of activity,
irrespective of changes in V̇O2max or other fitness parameters (9,76–78). The information, obtained from the physical
activity logs as well as the heart rate and activity monitors,
indicated that participants were exercising at a level suitable
for obtaining such health benefits.
Caregivers assigned to the nutrition education program
evidenced significant 12-month improvements in the percentage of total calories reported from all fats as well as saturated fats to below the recommended 30% and 10% levels,
respectively (79). These changes were similar to those reported in other 1-year dietary intervention studies, many of
which involved more intensive interventions (80,81). Significant reductions were also observed in daily servings of
fats, oils, sweets, and high-fat snacks. The nutrition program represents one of the few systematic attempts to deliver ongoing nutrition counseling via telephone as opposed
to face-to-face formats (82). The study results provide a
starting point for the continued development of nutrition
programs tailored to the needs of different caregiver subgroups (i.e., caregivers of other patient populations).
The telephone delivery format used for both health behavior programs has been shown to be a convenient, flexible, and potentially low-cost alternative to the more traditional group-based health promotion programs offered in
the community (16,83). Participants received a 30- to 40minute face-to-face introductory counseling session, with
the remainder of the program delivered via biweekly, then
monthly, telephone and mail contacts. Studies with other
populations suggest that this frequency of telephone contact
could potentially be reduced once the program is established (84,85). Volunteer and service organizations operating through health centers and other settings could deliver
this type of support (16).
Although the inclusion of an attention-control condition
allowed us to rule out subject expectancy effects related to a
number of the outcomes of interest, the lack of a wait-list or
assessment-only condition prevents a clear interpretation of
the improvement in psychological distress outcomes noted
in both conditions. The improvements shown in both groups
on the depression and stress outcomes were notable (10)
(e.g., at 12 months, participants in both conditions had reduced their BDI score to below the cut point often used for
mild depression) (67). However, evaluation of the relative
efficacy of health behavior interventions compared with
psychosocial interventions aimed specifically at reducing
psychological distress in caregivers awaits study designs
that explicitly compare such different interventions directly
(43). The pre- to post-test changes in psychological distress
observed could be due to actual improvement stemming
from participation in a health promotion program, regardless of content, or to repeat testing or other time-related impacts. Unfortunately, the documented difficulty of maintaining caregivers in wait-listed or assessment-only control
conditions, even for short time periods (86,87), prevented
the use of that type of control condition in the current study.
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KING ET AL.
In addition, although the 85% 12-month response rate is
similar to 12-month return rates for other, noncaregiving
older adult samples (31,88), nonreturning caregivers were
more distressed and reported a greater number of hours
spent in caregiving duties at baseline relative to those who
returned for clinical assessment. These results are similar to
those from a study evaluating dementia caregivers who required assessment in their homes as opposed to in a university setting (89). In that study, those assessed at home were
more depressed and provided more hours of care per day
than those who could attend clinic-based assessments. Continued efforts to reach this particularly distressed caregiver
segment are indicated. Other limitations of the study include
the fact that the sample was primarily white and well educated, limiting the generalizability of the results for more
ethnically diverse caregiving populations.
We conclude that properly tailored health promotion programs can promote sustained improvements in health behaviors that are important to the ongoing health and functioning of older women family caregivers. The crucial and
increasingly prevalent societal role that family caregivers
play in providing an alternative to institutionalization exacts
a tremendous physical, emotional, and economic cost for
the caregiver herself and provides the rationale for continued development of programs to preserve both the caregiver’s health and quality of life.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
Acknowledgments
This research was supported by the National Institute on Aging (Public
Health Service grant AG-12358). Statistical support was provided by David
Ahn, PhD. We thank Patrick Henderson, Debbie Flandermeyer, and Karen
Bolen for their help with data collection.
22.
Address correspondence to Abby C. King, PhD, Stanford University
School of Medicine, 730 Welch Road, Suite B, Palo Alto, CA 94304-1583.
E-mail: [email protected]
24.
23.
25.
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Received October 9, 2000
Accepted February 14, 2001
Decision Editor: John E. Morley, MB, BCh