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The effect of moderate aerobic exercise on physical fitness among women 70 years and older
Mururifus, 14 (1991) 49-56 Elsevier Scientific Publishers Ireland Ltd.
49
MAT 00639
The effect of moderate aerobic exercise on physical fitness among women 70 years and older C.K. Probarta, M. Notelovitzb, D. Martinc, F.Y. Khand and C. Fieldsb *Department of Health Science Education, College of Health & Human Performance, University of Florida. Gainesville, Florida, ‘The Center for Climacteric Studies, Inc., Women S Medical and Diagnostic Center, Gainesville. Florida, “Department of Physical Therapy, College of Health-Related Professions, University of Florida. Gainesville. Florida and “Department of Pathology, College of Medicine, University of Florida, Gainesville, Florida (U.S. A.)
(Received December 7, 1990; revision received May 28. 1991; accepted
June
4,
19$11)
This study investigated benefits of 26 weeks of moderate aerobic exercise for women 70 years or older. Sixteen healthy women with a mean age of 72.0 years were randomized into exercise (n = IO) and control groups (n = 6). The exercise group walked on a treadmill 3 times per week for 20 mitt, at 70% of maximum heart rate. Oxygen uptake V02,, expressed in I/min and ml. kg-’ . min-‘, total exercise time on the treadmill (TET), maximum heart rate (HR,,,) and body mass index (BMI) were measured at baseline and 6 months. Two-way repeated measures analysis of variance (ANOVA) determined the effect of exercise intervention. Both measures of VOZmilnin addition to TET were significantly improved by the moderate training program, compared to the control group. VOzmaxin the exercise group increased by +6.6X (S.E. 2.9) measured in I/min and 8.4% (SE. 3.2) measured in ml . kg-’ min-t. TET increased by 25.4% (S.E. 4.9) in the exercise group. The ANOVA was unable to detect significance between the exercise and control groups for HR,,, or BML All exercising subjects finished the program, apparently tolerating the intervention. The results indicate that healthy women over the age of 70 years can increase fitness measures with a moderate training program.
Key words: exercise; VO, max; elderly; cardiorespiratory
fitness: females
Introduction
Recommendations for aerobic exercise for women over the age of 70 years have been mixed because of uncertainty regarding benefits and the possibility of poor compliance and injury. Some question the benefit and safety of aerobic exercise for older individuals [l]. Others suggest a healthy lifestyle including exercise may increase quality of life, and possibly extend life, into the 8th and 9th decade [2,3]. Summary recommendations of the Physical Fitness and Exercise working group from the Correspondence ro: Morris Notelovitz. MD, Ph.D. Women’s Medical and Diagnostic Center, 222 SW. 36th Terrace, Suite C, Gainesville, FL 32607, U.S.A.
0378-5122/91/SO3.500 1991 Elsevier Scientific Publishers Ireland Ltd. Printed and Published in Ireland
50
Surgeon General’s Workshop on Health Promotion and Aging, point to the lack of research in the area of appropriate physical activity for older persons, specifically women, and suggest that ‘Research should determine the appropriate types and levels of physical activity (i.e., in terms of intensity, frequency, and duration) necessary to safely achieve the potential benefits in health and functional capacity...’ p. 2507 [4]. Of the reports that have been published on training benefits for older persons in general, conclusions regarding cardiovascular benefits have been mixed. Research conducted before the 1980s was inconclusive in uncovering increases in fitness measurements such as oxygen uptake [5,6]. However most studies conducted with older subjects within the last 10 years have identified change in a variety of measures resulting from exercise, including psychological gains [7,8] and increased strength and muscle mass [9,10], in addition to cardiorespiratory improvements [ll-181, shown in Table I. Previously, many studies have considered everyone over the age of 50 years to be one homogeneous group, without considering persons age 70 and above might respond differently to exercise. To date, few studies have focused on the ability of older individuals to tolerate endurance exercise or improve cardiorespiratory status. In addition, research exists that suggests women and men differ in benefits gained from exercise [ 1,4,6,8,13]. However, few studies have been identified that focus exclusively on women aged 70 years or older, who may be unique in their tolerance and response to endurance training. In one study of a mixed gender sample of 70-79-year-old subjects, Hagberg et al. [ 121 found an increase in VOzmaxin the aerobic exercise group (aerobic exercise n = 21, resistance training, n = 23, control group n = 13). Subjects increased VOzmax 16% during the first 13 weeks at moderately intense exercise (50-70% HR,,,). Exercise level was intensified for the next 13 weeks, to 75-85% maximum heart rate, during which time VOZ,,,~~increased an additional 6%, for a total of 22% increase by the end of the 26 week study. A fairly high attrition rate (24%) was reported in the exercise group. Reasons for the attrition were not discussed, nor was it indicated if dropouts were male or female. Others have found gender differences in response to aerobic exercise, with males typically showing greater improvement. Blumenthal et al. [8] in their study of 100 older men and women (mean age 67 years) found men increased VOZmaxby 14.4%, while women improved by only 8.6% after 16 weeks of exercise for 30 min at 70% maximum heart rate, in a walking/jogging program. Juneau, et al. [13] in a population of middle aged men and women (mean age 50 years) found men improved by 14% and women by only 9% after participating in exercise 65-77% of VOZmax maximum heart rate, including walking and jogging for 45-60 min daily for 26 weeks. In addition, in Juneau’s study, the rate of attrition appeared different by gender, with 3 men and 10 women dropping out. It appears that women respond differently to exercise, with levels of improvement of VOZmaxof 8-g%, making the comparison to mixed gender studies difficult. In addition, tolerance of older women to exercise may be lower than that of older men, increasing attrition and injury in females. In the only study identified with exclusively older female subjects, Foster et al. [ 181 studied aerobic exercise response in 24 women recruited from independent-living
63
II
56
8 8 16 72
Foster et al., 1989 [18]
Probart et al., 1991 (present study) White et al., 1984 [lo]
78 78 72
14 14 57 68
61 >70 50
63
(years)
Mean age
101 41 120
88
N
26
10 10 24
9 9
52
16 13 26
52
Training (weeks)
FROM AEROBIC TRAINING
Cowan and Gregory, 1984 [ 171 Badenhop et al., 1983 [I I]
Female population
Blumenthal et al., 1989 [8] Hagberg et al., 1989 [I21 Juneau et al., 1987 [13] Seals et al., 1987 [I41 Yerg et al., 1985 [I61
Mixed populations
Thomas et al., 1985 [15] Men only
Male populations
Author and date
COMPARISON OF VOZmaxRESULTING
TABLE I
33
20
60 25
27
30 40 50
30
Duration (min)
70
80 57 70 40 60 70
50-80
70 50-70 77
4
4 3 3 3 3 3
4-5
3 3 5
3
Frequency (per week)
FROM 1980 TO PRESENT
Intensity (‘l/uHR nl*x)
IN OLDER POPULATIONS
-
19 16 15 13 15 8
22
II 16 12
12
(ml. kg-’ . min-‘)
VOZmax
u/uGain
52
retirement homes, ranging in ages from 67-89 years, with a mean of 78.4 years. In the IO-week study, subjects increased oxygen uptake by 13-l% depending on intensity. However, comparison to other research is difficult as low baseline values for V%ax and HR,,, and the fact that the subjects were recruited from a congregate living site, suggest the population may have been quite different from free-living subjects. The purpose of the present study was to determine if previously sedentary, healthy women aged 70 years or older will tolerate moderate aerobic exercise and increase measures of physical fitness in a structured, 26-week training program. Method Subjects for the study included 16 healthy women aged 70 and over selected from a university community in north-central Florida, United States of America. General good health was required for participation, and physical examinations were performed to determine health status. Exclusion criteria included cardiovascular or pulmonary disease, medications that might interfere with analysis of the exercise protocol, including hormone therapy, or problems with mobility. Participants were randomized into exercise (n = 10) and control groups (n = 6). More subjects were allocated to the exercise group in anticipation of greater attrition from that group. Written informed consent was obtained prior to data collection. To assess physical fitness, participants were screened for cardiovascular normalcy by 12 lead electrocardiogram stress tests. Maximal oxygen uptake (VOZmax) was determined by a modified Balke and Ware treadmill protocol [19]. Each subject’s VOZmaxwas measured with a Beckman Metabolic Measurement Cart at the start of the study and following 6 months of training. The gas analyzers were calibrated with precision gases prior to each test, and calibration was verified following each test to insure that there had not been unacceptable analyzer drift during the test. Temperature transducer and volume turbine calibration were verified prior to each test. Electrocardiograph tracings were used to monitor lead Vs every 60 s during the test. Speed of the treadmill was constant at 3 miles/h, while elevation increased at 1% each subsequent minute. Criteria for attaining VOZmaxwere: a failure to increase 02 uptake despite an increase in treadmill grade; reaching 95% of age-adjusted maximal heart rate; and respiratory exchange ratio greater than 1.15 at exhaustion. Maximum heart rate (HR,,,) was considered to be the highest of three consecutive measures recorded by the electrocardiogram. Variables measured were relative VOZmax(ml . kg-’ +min-‘), absolute VOZmax (l/min), total exercise time in mins (TET), height and weight. The latter two measures were used to calculate body mass index (BMI = kg/m*). In addition, maximum heart rate in beats/min (HR,,,) was measured over time to assure differences did not occur, indicating actual maximum levels were attained at baseline V02max measurement. Exercise group subjects received aerobic exercise training consisting of walking on a treadmill 3 times per week for 20 min, at 70% of measured maximum heart rate. All training sessions were monitored, one-on-one by trained personnel to assess attainment of target exercise intensity and exercise tolerance. Exercise tolerance was monitored by research staff using continual participant feedback and
II
OF WOMEN
ABOVE group
9.9 (1.17)
72 (0.60) 21.2 (1.2) 1.34 (0.04) 25.5 (1.3) 163.7 (1.3)
Baseline
Exercise
12.07 (1.21)**
I .43 (0.07)* 25.1 (1.2) 162.3 (1.4)
22.8 (1.3)**
6 Months
AEROBIC
(3.2)# (2.9)# (0.1) (0.4)
+25.4 (4.9)#
+8.4 +6.6 -0.1 -0.8
‘%bChange
OF MODERATE
n = IO, Mean (S.E.)
AGE 70 TO 6 MONTHS group
10.9 (0.76)
repeated
measures
10.3 (l.03)**
23.7 (1.8)** 1.34 (o.lo)* 23.5 (1.1) 168.7 (2.5)
6 Months
n = 6, Mean (S.E.)
OR NON-EXERCISING
72 (0.68) 25.1 (1.4) I .4l (0.08) 23.3 (1.1) 175.8 (1.5)
Baseline
Control
EXERCISE
Between group differences between change in exercise group compared to change in control. based on two-way **P< 0.01. Within group differences from baseline to 6 months, based on post hoc r-test. #P < 0.05.
Time (mitt)
Age V02,,,(ml . kg-’ mitt-‘) VOz,,,(l/min) Body Mass Index (kg/m*) Heart rate,,, (beats/min) Total exercise
Variable
RESPONSES
TABLE
ANOVA.
-5.4
-6.1 -5.0 +o. I -4.0
*P < 0.05:
(4.3)
(3.0) (3.2) (0.01) (0. I)
u/j Change
CONTROLS
54
periodic, informal, individual interviews. Subjects in the control group received no intervention and were instructed not to engage in systematic exercise for the duration of the study. Two-way repeated measures analysis of variance (Exercise Group x Time) was used to compare the rate of change for the exercise versus the control group, with used as deV02max measured in l/min and ml * kg.-’ * min-‘, TET, BMI and HR,,, pendent variables. Post hoc t-tests were performed to detect within group changes over time (baseline compared to 6 months) for each group, when the ANOVAs were significant. Significance was considered at the 0.05 probability level. Results
Average age of the subjects was 72.0 years (S.E. = 0.60) for the exercise group and 72.0 (S.E. = 0.68) for the control group. All subjects in both the intervention and control groups remained in the study for the 6-month period. Baseline and 6-month measurements for study variables are summarized in Table II. Control group means at baseline were slightly higher for I/min, ml. kg-’ . min-‘, TET and HR,,, and slightly lower for BMI. These baseline differences, however, were not statistically significant. The exercise group increased VOZmaxmeasured by I/min (+6.6% S.E. = 2.9) and ml * kg-’ * min-’ (+8.4% S.E. = 3.2). Controls decreased V02max (l/min, -5.0% S.E. = 3.2; ml * kg-’ * min-‘, -6.1% S.E. = 3.0) from baseline values. These treatment group differences were significant when expressed both as l/min and ml - kg-’ . min-‘, compared to the control group, as determined by significant interaction (Group x Time) in the ANOVA for the 2 VOZmaxmeasures. Post-hoc f-tests were significant at the 0.05 level for VOZmax(both l/min and ml/kg per min) for the exercise group, but not for the control group, indicating within group changes occurred for the exercisers but not for controls. Total exercise time on the treadmill paralleled changes in oxygen consumption. Exercise groups means increased by 25.4% (S.E. = 4.9) and control group decreased by 5.4% (S.E. = 4.3). These group differences were significant (P < 0.001). Within group differences from baseline to 6 months were also significant for the activity group (P < 0.001) but not controls (P = 0.22). Body mass index means were within the 50% percentile range for age at baseline, according to National Health Survey statistics [20,21], and did not change significantly, based on the ANOVA. Maximum heart rate during treadmill testing appeared to decrease slightly in the control group. However, the decrease approximated day to day physiologic variation, and was not statistically significant. Stability in maximum heart rate for the treatment group suggested HR,,, was achieved during the initial VOZmaxtesting at baseline. Based on the fact that 100% of the subjects completed the 6-month program, no injuries or serious discomfort were reported, and informal interviews and feedback to staff were positive, the program appeared to be tolerated by the subjects. Discussion
Utilization of VOzmaxas an indicator of fitness in older subjects has been questioned by some [22,23]. However, VOZmaxhas been found reproducible in the
55
healthy older population by others [24,25] and was confirmed in this study by stability of HR,,, and respiratory quotient values in excess of 1.15. In addition, typical of exercise studies using volunteers, subjects in this study were healthy and wellmotivated, limiting generalization to less healthy older females. Little has been reported previously about the ability of women 70 years and older to respond to aerobic training in the moderate range of exercise intensity. The present study utilized a moderate walking program over a 26-week training period to determine the response and tolerance of older females to aerobic exercise. The training protocol of 70”/;,maximum heart rate reported in the present study was apparently well tolerated. In addition, cardiorespiratory fitness and functional status improved significantly in the exercise treatment group over time and as compared to controls. The greater response in VOZmaxreported by others with subjects in the same age range, may be explained by the inclusion of males and increased exercise intensity (Hagberg et al. [ 12]), and differences in exercise protocol (Foster et al. [ 181).The rate of improvement in VOZmaxreported by the current study (8.4%) was consistent with the improvement reported for younger women by both Blumenthal et al. of 8.6% [8] and Juneau, et al. of 9% [13]. Although a moderate walking program may be less effective than more intense exercise in increasing VOZmax[12], indication of signiticant improvement was detected without the attrition and injury reported in higher intensity exercise programs [6,12,26,27]. The 1979 Health Goals for the United States list increased functional status and independence as high national priorities for older adults [28]. The U.S. Surgeon General’s Workshop on Health Promotion and Aging also suggests moderate aerobic exercise for aging adults [4]. Increased functional status by moderate exercise may foster far reaching consequences including greater mobility and increased social interaction, which could enhance well being [2-4,21,28-301. Yet, up to onethird of non-institutionalized older Americans report some form of functional disability, at least partially related to disuse [ 1,281. Activity level of older women in the United States is clearly very low and needs to be increased [4,29-3 I]. However, intense exercise may not be well tolerated by older individuals. The present research supported other findings [3] that intense aerobic exercise is not necessary for improvements in various parameters of health status. Oxygen uptake and functional status measured by total exercise time were improved with moderate walking, at levels of intensity practical for previously sedentary older women. References I
Wheat
2
Freis J. Aging, natural
3
Blair SN, Kohl HW,
ME.
Exercise in the elderly.
all-cause mortality. 4
West J Med
death, and compression
Paffenbarger
RS, Clark
1987; 145: 477-480. of morbidity.
DG,
Cooper
Gibbons
1980; 33: 130-135.
LW. Physical fitness and
J Am Med Assoc 19119; 262:2395-2437.
Centers for Disease Control summary recommendations
(CDC).
Surgeon General’s
workshop
of physical fitness and exercise working
5
262: 2507-2510. Adams GM, deVries
6
52 to 79. J Gerontol 1973; 28: 50-55. Niinimaa V, Shephard RJ. Training and oxygen conductance system. J Gerontol
N Engl J Med
KH,
HA.
Physiological
1978; 33: 362-367.
on health promotion
and aging:
group. J Am Med Assoc 1989;
effects of an exercise training
regimen upon women aged
in the elderly. iI The cardiovascular
56 7 8
9 10
II 12
13
14 I5 16 17 18 I9
20
21 22 23 24 25 26 27 28
29 30 31
Emery CF. Blumenthal JA. Perceived change among participants in an exercise program for older adults. The Gerontolgist 1990; 30: 516-521. Blunlenthal JA, Emery CF. Madden DJ, George LK. Coleman RE. Riddle MW, McKee DC, Reasoner J, Williams RS. Cardiovascular and behavioral effects of aerobic exercise training in healthy older men and women. J Gerontol 1989; 44: Ml47-Ml57. Fiatarone MA, Marks EC, Ryan ND, Meredity CN. Lip&z LA, Evans WJ. High-intensity strength training in nonagenarians. J Am Med Assoc 1990: 263: 3029-3034. White MK. Yeater RA, Martin RB, Rosenberg BS, Sherwood L. Weber KC. Della Giustina DE. Effects of aerobic dancing and walking on cardiovascular function and muscular strength in postmenopausal women. J Sports Med 1984; 24: 159-166. Badenhop DT, Cleary PA, Schaal SF, Fox EL, Bartels RL. Physiological adjustments to higher- or lower- intensity exercise in elders. Med Sci Sports Exert 1983: 15: 496-502. Hagberg JM. Graves JE, Limacher M, Woods DR. Leggett SH, Cononie C. Gruber JJ. Pollock M. Cardiovascular responses of 70-79-yr-old men and women to exercise training. J Appl Physiol 1989: 66: 2589-2594. Juneau M. Rogers F, DeSantos V. Yee M. Evans A, Bohn A. Haskell WL, Taylor CB. DeBusk RF. Effectiveness of self-monitored. home based, moderate-intensity exercise training in middle-aged men and women. Am J Cardiol 1987; 60: 66-70. Seals DR, Hagberg JM, Hurley BF. Ehsani AA, Holloszy JO. Endurance training in older men and women: I. Cardiovascular responses to exercise. J Appl Physiol 1984: 57: 1024-1029. Thomas SG, Cunningham DA, Rechnitzer PA, Donner AP, Howard JH. Determinants of the training response in elderly men. Med Sci Sports Exert 1985; 17: 667-672. Yerg II JE, Seals DR. Hagberg JM, Holloszy JO. Effect ofendurance exercise training on ventilatory function in older individuals. J Appl Physiol 1985: 58: 791-794. Cowan MM, Gregory LW. Responses of pre- and post-menopausal females to aerobic conditioning, Med Sci Sports Exert 1985; 17: 138-143. Foster VL, Hume GJ, Byrnes WC, Dickinson AL, Chattield SJ. Endurance training for elderly women: Moderate vs. low intensity. J Gerontol: Med Sci 1989; 44: M 184-M 188. Notelovitz M, Fields C, Caramelli K, Dougherty M, Schwartz AL. Cardiorespiratory fitness evaluation in climacteric women: Comparison of two methods. Am J Obstet Gynecol 1986: 154: 1009-1013. National Center for Health Statistics, Najjar MF. Rowland M. Anthropometric reference data and prevalence of overweight, United States, 1976-80. Vital and Health Statistics. Series I I, No. 238. DHHS Pub. No. (PHS) 87-1688. Public Health Service. Washington. U.S. Government PrintingOffice, Oct. 1987. Gelein JL. Aged women and health. Nurs Clin North Am 1982: 17: 179-185. Chodzko-Zajko WJ, Ringel RL. Physiological fitness measures and sensory and motor performances in aging. Exp Gerontol 1987; 22: 317-328. Posner JD, Gorman KM. Klein HS. Woldow A. Exercise capacity in the elderly. Am J Cardiol 1986: 57: 52c-58~. Foster VL, Hume GJE, Dickinson AL. Chatfield SJ, Byrnes W. The reproducibility of VOzmaxventilatory. and lactate thresholds in elderly women. Med Sci Sports Exert 1986: 18: 425-430. Bruce RA. Exercise, functional aerobic capacity. and aging-another viewpoint. Med Sci Sports Exert 1984; 16: 8-13. Hurley BF, Seals DR. Ehsani AA, Cartier LJ, Dalsky GP. Hagberg JM. Holloszy JO. Effects of high-intensity strength training on cardiovascular function. Med Sci Sports Exert 1984; 16: 483-498. Kilbom A. Hartley LH, Saltin B. Bjure J. Grimby G. Astrand I. Physical training in sedentary middle-aged men and older men. I. Medical evaluation. Stand J Clin Lab Invest 1969; 24: 315-327. Public Health Service, Office of the Assistant Secretary for Health and Surgeon General. Healthy People. The Surgeon General’s Report on Health Promotion and Disease Prevention. (DHEW Publication No. 79-55071). Washington, DC: U.S. Government Printing Oftice. 1979. Shephard RJ, Montelpare W: Geriatric benefits of exercise as an adult. J Gerontol: Med Sci 1988: 43: M86-M90. Fitzgerald PL. Exercise for the elderly. Med Clin N Am 1985; 69: 189-196. Heckler MM. Health promotion for older Americans. Public Health Rep 1985: 100: 225-230.
49
MAT 00639
The effect of moderate aerobic exercise on physical fitness among women 70 years and older C.K. Probarta, M. Notelovitzb, D. Martinc, F.Y. Khand and C. Fieldsb *Department of Health Science Education, College of Health & Human Performance, University of Florida. Gainesville, Florida, ‘The Center for Climacteric Studies, Inc., Women S Medical and Diagnostic Center, Gainesville. Florida, “Department of Physical Therapy, College of Health-Related Professions, University of Florida. Gainesville. Florida and “Department of Pathology, College of Medicine, University of Florida, Gainesville, Florida (U.S. A.)
(Received December 7, 1990; revision received May 28. 1991; accepted
June
4,
19$11)
This study investigated benefits of 26 weeks of moderate aerobic exercise for women 70 years or older. Sixteen healthy women with a mean age of 72.0 years were randomized into exercise (n = IO) and control groups (n = 6). The exercise group walked on a treadmill 3 times per week for 20 mitt, at 70% of maximum heart rate. Oxygen uptake V02,, expressed in I/min and ml. kg-’ . min-‘, total exercise time on the treadmill (TET), maximum heart rate (HR,,,) and body mass index (BMI) were measured at baseline and 6 months. Two-way repeated measures analysis of variance (ANOVA) determined the effect of exercise intervention. Both measures of VOZmilnin addition to TET were significantly improved by the moderate training program, compared to the control group. VOzmaxin the exercise group increased by +6.6X (S.E. 2.9) measured in I/min and 8.4% (SE. 3.2) measured in ml . kg-’ min-t. TET increased by 25.4% (S.E. 4.9) in the exercise group. The ANOVA was unable to detect significance between the exercise and control groups for HR,,, or BML All exercising subjects finished the program, apparently tolerating the intervention. The results indicate that healthy women over the age of 70 years can increase fitness measures with a moderate training program.
Key words: exercise; VO, max; elderly; cardiorespiratory
fitness: females
Introduction
Recommendations for aerobic exercise for women over the age of 70 years have been mixed because of uncertainty regarding benefits and the possibility of poor compliance and injury. Some question the benefit and safety of aerobic exercise for older individuals [l]. Others suggest a healthy lifestyle including exercise may increase quality of life, and possibly extend life, into the 8th and 9th decade [2,3]. Summary recommendations of the Physical Fitness and Exercise working group from the Correspondence ro: Morris Notelovitz. MD, Ph.D. Women’s Medical and Diagnostic Center, 222 SW. 36th Terrace, Suite C, Gainesville, FL 32607, U.S.A.
0378-5122/91/SO3.500 1991 Elsevier Scientific Publishers Ireland Ltd. Printed and Published in Ireland
50
Surgeon General’s Workshop on Health Promotion and Aging, point to the lack of research in the area of appropriate physical activity for older persons, specifically women, and suggest that ‘Research should determine the appropriate types and levels of physical activity (i.e., in terms of intensity, frequency, and duration) necessary to safely achieve the potential benefits in health and functional capacity...’ p. 2507 [4]. Of the reports that have been published on training benefits for older persons in general, conclusions regarding cardiovascular benefits have been mixed. Research conducted before the 1980s was inconclusive in uncovering increases in fitness measurements such as oxygen uptake [5,6]. However most studies conducted with older subjects within the last 10 years have identified change in a variety of measures resulting from exercise, including psychological gains [7,8] and increased strength and muscle mass [9,10], in addition to cardiorespiratory improvements [ll-181, shown in Table I. Previously, many studies have considered everyone over the age of 50 years to be one homogeneous group, without considering persons age 70 and above might respond differently to exercise. To date, few studies have focused on the ability of older individuals to tolerate endurance exercise or improve cardiorespiratory status. In addition, research exists that suggests women and men differ in benefits gained from exercise [ 1,4,6,8,13]. However, few studies have been identified that focus exclusively on women aged 70 years or older, who may be unique in their tolerance and response to endurance training. In one study of a mixed gender sample of 70-79-year-old subjects, Hagberg et al. [ 121 found an increase in VOzmaxin the aerobic exercise group (aerobic exercise n = 21, resistance training, n = 23, control group n = 13). Subjects increased VOzmax 16% during the first 13 weeks at moderately intense exercise (50-70% HR,,,). Exercise level was intensified for the next 13 weeks, to 75-85% maximum heart rate, during which time VOZ,,,~~increased an additional 6%, for a total of 22% increase by the end of the 26 week study. A fairly high attrition rate (24%) was reported in the exercise group. Reasons for the attrition were not discussed, nor was it indicated if dropouts were male or female. Others have found gender differences in response to aerobic exercise, with males typically showing greater improvement. Blumenthal et al. [8] in their study of 100 older men and women (mean age 67 years) found men increased VOZmaxby 14.4%, while women improved by only 8.6% after 16 weeks of exercise for 30 min at 70% maximum heart rate, in a walking/jogging program. Juneau, et al. [13] in a population of middle aged men and women (mean age 50 years) found men improved by 14% and women by only 9% after participating in exercise 65-77% of VOZmax maximum heart rate, including walking and jogging for 45-60 min daily for 26 weeks. In addition, in Juneau’s study, the rate of attrition appeared different by gender, with 3 men and 10 women dropping out. It appears that women respond differently to exercise, with levels of improvement of VOZmaxof 8-g%, making the comparison to mixed gender studies difficult. In addition, tolerance of older women to exercise may be lower than that of older men, increasing attrition and injury in females. In the only study identified with exclusively older female subjects, Foster et al. [ 181 studied aerobic exercise response in 24 women recruited from independent-living
63
II
56
8 8 16 72
Foster et al., 1989 [18]
Probart et al., 1991 (present study) White et al., 1984 [lo]
78 78 72
14 14 57 68
61 >70 50
63
(years)
Mean age
101 41 120
88
N
26
10 10 24
9 9
52
16 13 26
52
Training (weeks)
FROM AEROBIC TRAINING
Cowan and Gregory, 1984 [ 171 Badenhop et al., 1983 [I I]
Female population
Blumenthal et al., 1989 [8] Hagberg et al., 1989 [I21 Juneau et al., 1987 [13] Seals et al., 1987 [I41 Yerg et al., 1985 [I61
Mixed populations
Thomas et al., 1985 [15] Men only
Male populations
Author and date
COMPARISON OF VOZmaxRESULTING
TABLE I
33
20
60 25
27
30 40 50
30
Duration (min)
70
80 57 70 40 60 70
50-80
70 50-70 77
4
4 3 3 3 3 3
4-5
3 3 5
3
Frequency (per week)
FROM 1980 TO PRESENT
Intensity (‘l/uHR nl*x)
IN OLDER POPULATIONS
-
19 16 15 13 15 8
22
II 16 12
12
(ml. kg-’ . min-‘)
VOZmax
u/uGain
52
retirement homes, ranging in ages from 67-89 years, with a mean of 78.4 years. In the IO-week study, subjects increased oxygen uptake by 13-l% depending on intensity. However, comparison to other research is difficult as low baseline values for V%ax and HR,,, and the fact that the subjects were recruited from a congregate living site, suggest the population may have been quite different from free-living subjects. The purpose of the present study was to determine if previously sedentary, healthy women aged 70 years or older will tolerate moderate aerobic exercise and increase measures of physical fitness in a structured, 26-week training program. Method Subjects for the study included 16 healthy women aged 70 and over selected from a university community in north-central Florida, United States of America. General good health was required for participation, and physical examinations were performed to determine health status. Exclusion criteria included cardiovascular or pulmonary disease, medications that might interfere with analysis of the exercise protocol, including hormone therapy, or problems with mobility. Participants were randomized into exercise (n = 10) and control groups (n = 6). More subjects were allocated to the exercise group in anticipation of greater attrition from that group. Written informed consent was obtained prior to data collection. To assess physical fitness, participants were screened for cardiovascular normalcy by 12 lead electrocardiogram stress tests. Maximal oxygen uptake (VOZmax) was determined by a modified Balke and Ware treadmill protocol [19]. Each subject’s VOZmaxwas measured with a Beckman Metabolic Measurement Cart at the start of the study and following 6 months of training. The gas analyzers were calibrated with precision gases prior to each test, and calibration was verified following each test to insure that there had not been unacceptable analyzer drift during the test. Temperature transducer and volume turbine calibration were verified prior to each test. Electrocardiograph tracings were used to monitor lead Vs every 60 s during the test. Speed of the treadmill was constant at 3 miles/h, while elevation increased at 1% each subsequent minute. Criteria for attaining VOZmaxwere: a failure to increase 02 uptake despite an increase in treadmill grade; reaching 95% of age-adjusted maximal heart rate; and respiratory exchange ratio greater than 1.15 at exhaustion. Maximum heart rate (HR,,,) was considered to be the highest of three consecutive measures recorded by the electrocardiogram. Variables measured were relative VOZmax(ml . kg-’ +min-‘), absolute VOZmax (l/min), total exercise time in mins (TET), height and weight. The latter two measures were used to calculate body mass index (BMI = kg/m*). In addition, maximum heart rate in beats/min (HR,,,) was measured over time to assure differences did not occur, indicating actual maximum levels were attained at baseline V02max measurement. Exercise group subjects received aerobic exercise training consisting of walking on a treadmill 3 times per week for 20 min, at 70% of measured maximum heart rate. All training sessions were monitored, one-on-one by trained personnel to assess attainment of target exercise intensity and exercise tolerance. Exercise tolerance was monitored by research staff using continual participant feedback and
II
OF WOMEN
ABOVE group
9.9 (1.17)
72 (0.60) 21.2 (1.2) 1.34 (0.04) 25.5 (1.3) 163.7 (1.3)
Baseline
Exercise
12.07 (1.21)**
I .43 (0.07)* 25.1 (1.2) 162.3 (1.4)
22.8 (1.3)**
6 Months
AEROBIC
(3.2)# (2.9)# (0.1) (0.4)
+25.4 (4.9)#
+8.4 +6.6 -0.1 -0.8
‘%bChange
OF MODERATE
n = IO, Mean (S.E.)
AGE 70 TO 6 MONTHS group
10.9 (0.76)
repeated
measures
10.3 (l.03)**
23.7 (1.8)** 1.34 (o.lo)* 23.5 (1.1) 168.7 (2.5)
6 Months
n = 6, Mean (S.E.)
OR NON-EXERCISING
72 (0.68) 25.1 (1.4) I .4l (0.08) 23.3 (1.1) 175.8 (1.5)
Baseline
Control
EXERCISE
Between group differences between change in exercise group compared to change in control. based on two-way **P< 0.01. Within group differences from baseline to 6 months, based on post hoc r-test. #P < 0.05.
Time (mitt)
Age V02,,,(ml . kg-’ mitt-‘) VOz,,,(l/min) Body Mass Index (kg/m*) Heart rate,,, (beats/min) Total exercise
Variable
RESPONSES
TABLE
ANOVA.
-5.4
-6.1 -5.0 +o. I -4.0
*P < 0.05:
(4.3)
(3.0) (3.2) (0.01) (0. I)
u/j Change
CONTROLS
54
periodic, informal, individual interviews. Subjects in the control group received no intervention and were instructed not to engage in systematic exercise for the duration of the study. Two-way repeated measures analysis of variance (Exercise Group x Time) was used to compare the rate of change for the exercise versus the control group, with used as deV02max measured in l/min and ml * kg.-’ * min-‘, TET, BMI and HR,,, pendent variables. Post hoc t-tests were performed to detect within group changes over time (baseline compared to 6 months) for each group, when the ANOVAs were significant. Significance was considered at the 0.05 probability level. Results
Average age of the subjects was 72.0 years (S.E. = 0.60) for the exercise group and 72.0 (S.E. = 0.68) for the control group. All subjects in both the intervention and control groups remained in the study for the 6-month period. Baseline and 6-month measurements for study variables are summarized in Table II. Control group means at baseline were slightly higher for I/min, ml. kg-’ . min-‘, TET and HR,,, and slightly lower for BMI. These baseline differences, however, were not statistically significant. The exercise group increased VOZmaxmeasured by I/min (+6.6% S.E. = 2.9) and ml * kg-’ * min-’ (+8.4% S.E. = 3.2). Controls decreased V02max (l/min, -5.0% S.E. = 3.2; ml * kg-’ * min-‘, -6.1% S.E. = 3.0) from baseline values. These treatment group differences were significant when expressed both as l/min and ml - kg-’ . min-‘, compared to the control group, as determined by significant interaction (Group x Time) in the ANOVA for the 2 VOZmaxmeasures. Post-hoc f-tests were significant at the 0.05 level for VOZmax(both l/min and ml/kg per min) for the exercise group, but not for the control group, indicating within group changes occurred for the exercisers but not for controls. Total exercise time on the treadmill paralleled changes in oxygen consumption. Exercise groups means increased by 25.4% (S.E. = 4.9) and control group decreased by 5.4% (S.E. = 4.3). These group differences were significant (P < 0.001). Within group differences from baseline to 6 months were also significant for the activity group (P < 0.001) but not controls (P = 0.22). Body mass index means were within the 50% percentile range for age at baseline, according to National Health Survey statistics [20,21], and did not change significantly, based on the ANOVA. Maximum heart rate during treadmill testing appeared to decrease slightly in the control group. However, the decrease approximated day to day physiologic variation, and was not statistically significant. Stability in maximum heart rate for the treatment group suggested HR,,, was achieved during the initial VOZmaxtesting at baseline. Based on the fact that 100% of the subjects completed the 6-month program, no injuries or serious discomfort were reported, and informal interviews and feedback to staff were positive, the program appeared to be tolerated by the subjects. Discussion
Utilization of VOzmaxas an indicator of fitness in older subjects has been questioned by some [22,23]. However, VOZmaxhas been found reproducible in the
55
healthy older population by others [24,25] and was confirmed in this study by stability of HR,,, and respiratory quotient values in excess of 1.15. In addition, typical of exercise studies using volunteers, subjects in this study were healthy and wellmotivated, limiting generalization to less healthy older females. Little has been reported previously about the ability of women 70 years and older to respond to aerobic training in the moderate range of exercise intensity. The present study utilized a moderate walking program over a 26-week training period to determine the response and tolerance of older females to aerobic exercise. The training protocol of 70”/;,maximum heart rate reported in the present study was apparently well tolerated. In addition, cardiorespiratory fitness and functional status improved significantly in the exercise treatment group over time and as compared to controls. The greater response in VOZmaxreported by others with subjects in the same age range, may be explained by the inclusion of males and increased exercise intensity (Hagberg et al. [ 12]), and differences in exercise protocol (Foster et al. [ 181).The rate of improvement in VOZmaxreported by the current study (8.4%) was consistent with the improvement reported for younger women by both Blumenthal et al. of 8.6% [8] and Juneau, et al. of 9% [13]. Although a moderate walking program may be less effective than more intense exercise in increasing VOZmax[12], indication of signiticant improvement was detected without the attrition and injury reported in higher intensity exercise programs [6,12,26,27]. The 1979 Health Goals for the United States list increased functional status and independence as high national priorities for older adults [28]. The U.S. Surgeon General’s Workshop on Health Promotion and Aging also suggests moderate aerobic exercise for aging adults [4]. Increased functional status by moderate exercise may foster far reaching consequences including greater mobility and increased social interaction, which could enhance well being [2-4,21,28-301. Yet, up to onethird of non-institutionalized older Americans report some form of functional disability, at least partially related to disuse [ 1,281. Activity level of older women in the United States is clearly very low and needs to be increased [4,29-3 I]. However, intense exercise may not be well tolerated by older individuals. The present research supported other findings [3] that intense aerobic exercise is not necessary for improvements in various parameters of health status. Oxygen uptake and functional status measured by total exercise time were improved with moderate walking, at levels of intensity practical for previously sedentary older women. References I
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Blair SN, Kohl HW,
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