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Departments of Medicine and Exercise and Sport Sciences, Center for Exercise Science, University of Florida, and Geriatric Research, Education and Clinical Center, Veterans Affairs Medical Center, Gainesville, Florida 32610
ABSTRACT
INTRODUCTION
METHODS
RESULTS
DISCUSSION
ACKNOWLEDGEMENTS
FOOTNOTES
REFERENCES
ABSTRACT 
Pollock, Michael L., Larry J. Mengelkoch, James E. Graves,
David T. Lowenthal, Marian C. Limacher, Carl Foster, and Jack H. Wilmore. Twenty-year follow-up of aerobic power and body composition of older track athletes. J. Appl.
Physiol. 82(5): 1508-1516, 1997.
The purpose was
to determine the aerobic power (maximal oxygen uptake) and body
composition of older track athletes after a 20-yr follow-up (T3). At 20 yr, 21 subjects [mean ages: 50.5 ± 8.5 yr at initial
evaluation (T1), 60.2 ± 8.8 yr at 10-yr follow-up (T2), and 70.4 ± 8.8 yr at 20-yr follow-up (T3)] were divided into three
intensity groups: high (H; remained elite; n = 9); moderate (M; continued
frequent moderate-to-rigorous endurance training;
n = 10); and low (L; greatly reduced
training; n = 2). All groups
decreased in maximal oxygen uptake at each testing point (H, 8 and
15%; M, 13 and 14%; and L, 18 and 34% from T1 to T2 and T2 to T3,
respectively). Maximal heart rate showed a linear decrease of
~5-7
beats · min
1 · decade1 and was independent
of training status. Body weight remained stable for the H and M groups
and percent fat increased ~2-2.5%/decade. Although fat-free
weight decreased at each testing point, there was a trend for those who
began weight-training exercise to better maintain it. Cross-sectional
analysis at T3 showed that leg strength and bone mineral density were
generally maintained from age 60 to 89 yr. Those who performed weight
training had a greater arm region bone mineral density than those who
did not. These longitudinal data show that the physiological capacities
of older athletes are reduced despite continued vigorous endurance
exercise over a 20-yr period (~8-15%/decade). Changes in body
composition appeared to be less than those shown for the healthy
sedentary population and were related to changes in training habits.
aging; maximal oxygen uptake; weight training; bone mineral
density
INTRODUCTION AFTER MATURITY, maximal oxygen uptake
( Although it has been suggested that the slopes of the regression in
A reduction in HRmax with age has
been shown to be linear, with an ~10
beat · min Changes in body composition with age are also greatly affected by
activity status, with more active individuals being less fat and able
to maintain FFW (27). Although these findings are consistent in the
literature for short-term longitudinal (~6 mo to 1 yr) and
cross-sectional studies (26), few data exist for longer term studies.
Therefore, the purpose of this investigation was to determine the
aerobic power and body composition of older track athletes after a
20-yr follow-up. This information is particularly important because
most of the longitudinal studies have been conducted on persons <60
yr of age.
METHODS Subjects. Twenty-seven male track
athletes were recruited to participate in the initial evaluation (T1)
(25). To qualify for the study, the athletes had to have trained
regularly for at least the preceding 2 yr and placed first, second, or
third in regional, national, or international competition in running (800 m or less, n = 6; 1,500 m or
longer, n = 17) or race-walking (5,000 m or longer, n = 2) events within the
preceding year. Twenty-five subjects returned for testing at the 10-yr
follow-up [T2; 9.8 ± 1.4 (SD) yr]. One subject who was
not in the original group at T1 was tested after the manuscript was
accepted for publication at T2 (n = 24) (23). Two subjects had died (homicide; cancer), and one subject was
not available for testing. Twenty-one of the original subjects returned
for testing at the 20-yr follow-up (T3; 20.0 ± 1.3 yr). The four
remaining subjects were unavailable for testing at T3: two had
orthopedic conditions that prevented regular exercise training (severe
hip arthritis; low back pain), one had Alzheimer's disease, and one
could not be located.
At T3, the subjects ranged from 60 to 92 yr of age (70.4 ± 8.8 yr;
20 white, 1 black; 15 runners, 6 walkers). Results from activity
questionnaires and personal interviews of the subject's training
intensity and level of competition at T3 were used to determine the
assignment of subjects into high (H;
n = 9)-, moderate (M;
n = 10)-, and low-intensity groups (L;
n = 2). The H group included subjects
whose usual training intensity was ~60-85%
HRmax reserve. In addition, they
performed an interval session or aerobic threshold training session
( No subject was using medications at T1 or T2. At T3, one subject
(group L, age 75 yr) was taking medication for
treatment of hypertension [a lisinopril-hydrochlorothiazide (25 mg) combination four times a day] and another (group
M, age 61 yr) was using flecainide acetate (125 mg
twice a day) to control for paroxysmail atrial fibrillation.
The present protocol (T3) was approved by the Institutional Review
Board of the University of Florida College of Medicine (Gainesville).
All subjects provided informed consent.
The subjects were instructed not to engage in vigorous physical
training, to abstain from drinking alcohol for a minimum of 24 h before
testing, and to report to the laboratory around 8:00 AM at least 12 h
postprandial. The subjects underwent a cardiopulmonary examination by a
physician before testing. After 15 min of quiet sitting, resting blood
pressure was determined by auscultation and resting HR was counted for
30 s.
Body composition. Body composition was
determined from height, weight, circumference, and skinfold fat
measurements. Anthropometric procedures followed the
recommendations described by Pollock and Wilmore (26). Skinfold fat
measurements were obtained from seven sites (chest, axilla, triceps,
subscapula, abdomen, suprailiac, and anterior thigh). Circumferences
were measured at the chest, waist, gluteal (hip), thigh, biceps, and
wrist. Chest expansion was determined by calculating the difference in
circumference between a full expiration and a full inspiration. Height
and circumference measurements were taken to the nearest 0.1 cm, total
body weight to the nearest 100 g, and skinfold fat to the nearest 0.5 mm. Anthropometric variables were taken by the same investigator at T1,
T2, and T3. The calculation of body density, percent fat, and
FFW has been previously described (23).
At T3, skinfold percent fat was compared with percent fat data obtained
from underwater weighing (UWW) and from dual-energy X-ray
absorptiometry (DXA). The UWW procedure was previously described (23).
Although only skinfold fat data were collected from all subjects at T1,
UWW was determined at T2 and T3 and DXA at T3. The mean values were
14.8 vs. 13.2% fat for the skinfold and UWW techniques, respectively,
at T2 (23). At T3, the mean values were 17.1, 18.4, and 16.8% fat for
the skinfold, UWW, and DXA methods, respectively. Thus, in our opinion,
the skinfold technique appears to be valid for use in this
investigation.
Bone mineral density (BMD) was assessed noninvasively with DXA (DPX-L,
Lunar Radiation, Madison, WI) only at T3. This information was used in
a cross-sectional analysis to compare BMD to age, years, and type of
training, including resistance (weight)-training activities. The sample
for this analysis included two additional marathon runners (ages 92 and
94 yr) who had won medals in recent national marathon competition.
Three scans were performed: anterioposterior total body, lateral spine
(L2 and
L3), and supine hip, providing information on the right trochanter. The same radiology technician performed and analyzed all scans.
Pulmonary function. Pulmonary function
measurements were determined by spirometry while the subjects were
seated. The subjects performed at least three forced expiratory volume
in 1 s (FEV1) and forced vital
capacity (FVC) maneuvers. Trials were repeated until two trials were in
close agreement ( Aerobic capacity. The subjects
performed maximal exercise on a motor-driven treadmill. At T1, all
subjects performed maximal treadmill exercise using either a multistage
running or walking protocol (depending on the subject's track
specialty), which has been previously described (25). At T2, all
subjects performed two maximal treadmill exercise tests over a 2-day
period. Because of the subjects' increased age, it was felt that a
diagnostic test using the standard Bruce protocol (26) was necessary to screen the subjects on day 1 to rule
out overt coronary heart disease (symptoms, arrhythmias, or ischemia).
On day 2, the original running or
walking protocol was utilized. The mean values between the two tests
were similar (run protocol, 49.7 vs. Bruce, 48.2 ml · kg At T1 and T3, Strength testing (T3 only). Lumbar
back strength was assessed by an isometric test of the lumbar extensor
muscles at seven different angles (0, 12, 24, 36, 48, 60, and 72°
of lumbar flexion) with the MedX (Ocala, FL) lumbar extension machine.
One-repetition maximum chest press and leg press exercises were
performed on Nautilus (Richmond, VA) chest press and leverage leg press
machines. The subjects began the test by lifting a light weight. This
was followed by incremental increases of 2.3-4.5 kg depending on
the difficulty of the previous lift. A 1-min rest was allowed between trials. The subjects continued to increase the weight lifted until they
reached the maximal amount of weight that could be lifted in one
repetition. Generally, four to five trials were used to reach one
repetition maximum (26).
Physical activity questionnaires and
interview. T1, T2, and T3 included the same activity
questionnaires that provided training information about the mode of
exercise and quantity and quality of training used the year before
testing. At T2 and T3, each subject had an extensive interview by the
same investigator. The purpose of the interview was to verify the
information provided on the questionnaires and to document on a
year-to-year basis (T2, years 0-10; T3, years
10-20) the nature and extent of their training program and to determine their level of competiveness. The subjects had
to be participating in resistance training using both upper and lower
extremity exercises a minimum of two times per week for a minimum of 2 yr before testing to be classified as a weight lifter.
Statistical analysis. Longitudinal
training data for anthropometric and metabolic measurements and
pulmonary function values were compared with a 3 (time) × 3 (group) or 2 (time) × 3 (group) repeated-measures analysis of
variance. When means were significantly different, contrast analyses
were performed to determine which individual treatment means were
significantly different. Cross-sectional strength and BMD data compared
by age groups at T3 were analyzed by one-way analysis of variance. When
a significant F ratio was observed,
Scheffé's post hoc analysis was used to determine which individual treatment means were significantly different. An independent t-test was used to compare differences
among variables between subjects who included regular resistance
training between T2 and T3. Simple and multiple regression techniques
were used to analyze the relationships among variables. Statistical
significance was accepted as P RESULTS Subjects. At T3, the H group averaged
70.4 ± 8.5 yr of age, the M group 69.8 ± 10.2 yr, and the L
group 73.5 ± 2.1 yr (P Table 1.
Training data and metabolic measurements
O2 max), pulmonary
ventilation
(Emax),
and heart rate (HRmax) decline
with age (2, 5, 9, 11, 16, 17, 19, 23, 25, 28, 29, 33). Fat-free weight
(FFW) and muscular strength also decrease (7, 14, 23, 27, 30), whereas
body fat increases significantly with age (23, 26). In a review of
multiple studies, Heath et al. (9) determined that in healthy men
O2 max declined ~9%/decade after the age of 25 yr. These same authors and others (5,
12, 17, 23, 29) have shown that if persons remain physically active and
body weight remains fairly stable, a decline in
O2 max with age will be
5%/decade.
O2 max with age may be
similar for active and sedentary persons, this interpretation may have
been a consequence of using cross-sectional data rather than the
results from longitudinal studies (5). Longitudinal studies conducted
on subjects both below and above 50 yr of age show that decreases in
O2 max are greatly
affected by the initial level of aerobic capacity and change in
activity status (5, 23, 26, 28).
1 · decade1
decline (16, 26). These findings seem to be supported more by
cross-sectional data than by longitudinal studies. Longitudinal data
suggest a 5-7 beat/min reduction in
HRmax with age, particularly in
groups below 55 yr of age (2, 11, 17, 23, 29, 33). Longitudinal studies
on older participants are more variable and generally lacking (11, 33).
85% HRmax reserve) 1 times
per week, and they continued participation in high-level competition.
They also maintained their elite athletic status by placing first, second, or third in national or international age-group championships the previous year. The M group included subjects whose usual training intensity was ~60-80%
HRmax reserve. These subjects only
occasionally competed. The L group changed their mode of activity from
running to walking. Their usual training intensity was 
70%
HRmax reserve, and they did not
compete. The two subjects in the L group reduced their activity levels
between T2 and T3 secondary to physical limitations (total hip
replacement; knee meniscectomy and prostate surgery).
5%). Reported values for
FEV1 and FVC were selected with
the "best test" method (single test that gives the largest sum of
FEV1 plus FVC) (1).
1 · min1;
P 0.05), and the highest value
attained for each subject was used to determine
O2 max at T2. At T3,
the Bruce protocol was utilized with the following
exceptions: the modified Naughton protocol (2-min stages)
(26) was used for two subjects who had orthopedic limitations.
O2 max
was determined by the Douglas bag method. At T2,
O2 max was determined
by an automated system that has been previously described (23).
Expiratory ventilation was measured with a Parkinson-Cowan dry-gas
meter (model CD-4) at T1 and T2 and a 150-liter Tissot spirometer
(Collins, Braintree, MA) at T3. Heart rate and electrocardiographic
measurements were recorded continuously during exercise with
multiple-lead electrocardiographic recordings and for 5-7 min of
recovery. Blood pressure was measured as previously described (23). At
T2 and T3, the rating of perceived exertion (RPE) was determined at the
end of each minute and at peak exercise (4).
0.05.
0.05 among groups). The average years of follow-up were also not significant
among groups (P 0.05); H group,
19.3 ± 1.7 yr; M group, 20.4 ± 0.7 yr; and L group, 20.9 ± 0 yr. Although the miles trained per week were generally the same from
T1 to T2 for the H and M groups, there was a significant reduction in
mileage per week from T2 to T3. The total miles trained between the H
and M groups at T3 were not significantly different. The major
difference in training for both the H and M groups was their
significant reduction in pace from T2 to T3 (Table
1).
All Subjects
High-Intensity Group
Moderate-Intensity Group
Low-Intensity Group
T1
T2
T3
T1
T2
T3
T1
T2
T3
T1
T2
T3
n
21
21
21
9
9
9
10
10
10
2
2
2
Age, yr
50.5 ± 8.5
60.2* ± 8.8
70.4
± 8.8 51.2 ± 7.6
60.4* ± 8.5
70.4
± 8.5 49.5 ± 10.3
59.5* ± 10.3
69.8
± 10.2 52.5 ± 2.1
62.5* ± 2.1
73.5
± 2.1
Follow-up, yr
9.8 ± 1.4
20.0
± 1.3
9.2 ± 1.9
19.3
± 1.7
10.1 ± 0.7
20.4
± 0.7
10.6 ± 0.1
20.9
± 0
Mileage, miles/wk
32.8 ± 23.8
27.1 ± 15.2
18.2* ± 11.7
38.3 ± 24.3
34.4 ± 18.9
21.9
± 15.2 30.6 ± 25.5
23.5 ± 8.5
17.0* ± 7.6
18.8 ± 5.3
12.0 ± 4.2
7.5 ± 0.7
Pace, min/miles
7.9 ± 1.3
8.6 ± 1.6
10.4§ ± 3.2
7.9 ± 1.4
8.3 ± 1.5
9.5
± 1.3 7.9 ± 1.4
8.7 ± 1.8
10.0
± 3.4 7.4 ± 0.1
8.8 ± 0.4
16.3
± 1.8
HRrest, beats/min
49 ± 8
48 ± 8
52
± 8 46 ± 7
47 ± 9
50 ± 10
52 ± 8
49 ± 7
54 ± 5
50 ± 3
48 ± 11
56 ± 8
HRmax, beats/min
174 ± 10
167* ± 10
161* ± 9
173 ± 13
165* ± 10
160
± 9 177 ± 8
171* ± 9
162
± 9 166 ± 6
159 ± 8
163 ± 3
O2 max
l/min
3.792 ± 0.615
3.465 ± 0.545
2.863§ ± 0.715
3.643 ± 0.470
3.390* ± 0.440
2.849
± 0.526 3.930 ± 0.750
3.593* ± 0.663
3.009
± 0.875 3.770 ± 0.580
3.165* ± 0.199
2.197
± 0.008
ml · kg
1 · min1
54.3 ± 8.0
50.1* ± 7.0
40.5
± 8.9 55.4 ± 8.7
52.1* ± 6.8
43.2
± 6.3 54.2 ± 7.7
50.0* ± 6.9
40.8
± 9.5 50.0 ± 8.7
42.3* ± 1.3
27.0
± 0.1
ml · kg
FFW
1 · min1 61.7 ± 7.5
58.7 ± 6.8
48.7§ ± 9.8
61.6 ± 9.0
59.7 ± 7.3
51.1
± 8.5 62.3 ± 6.4
59.2* ± 6.4
49.3
± 10.0 59.0 ± 9.6
51.4* ± 1.7
34.5
± 0.2
O2 pulse, ml/beat
21.9 ± 3.7
20.8 ± 3.3
17.8§ ± 4.7
21.2 ± 3.0
20.5 ± 2.3
17.8
± 3.2 22.3 ± 4.6
21.1 ± 4.4
18.6
± 5.9 22.7 ± 2.7
20.0 ± 0.3
13.5
± 0.3
Emax, l/min
BTPS 144.0 ± 23.4
151.4 ± 20.0
117.4
± 24.7 143.0 ± 19.4
148.6 ± 18.3
117.5
± 14.7 145.5 ± 29.8
154.6 ± 23.9
122.3
± 31.1 142.0 ± 15.6
147.9 ± 2.7
92.2
± 14.4
RER
1.11 ± 0.07
1.11 ± 0.05
1.13 ± 0.07
1.10 ± 0.08
1.11 ± 0.06
1.12 ± 0.05
1.11 ± 0.07
1.09 ± 0.05
1.14 ± 0.08
1.14 ± 0.01
1.14 ± 0.02
1.15 ± 0.06
Perceived exertion
19.1 ± 0.8
19.2 ± 0.8
19.3 ± 0.7
19.1 ± 0.3
19.0 ± 0.9
19.2 ± 1.0
18.5 ± 0.7
19.5 ± 0.7
Values are means ± SD; n, no. of subjects except
n = 20 for all subjects and 8 for high-intensity group initial
evaluation (T1) respiratory exchange ratio (RER) and n = 20 for
all subjects and 9 for moderate-intensity group T1 resting heart rate
(HRrest) and maximal ventilation
(
Emax). T2, 10-yr
follow-up; T3, 20-yr follow-up; HRmax, maximal HR;
O2 max, maximal
O2 uptake; FFW, fat-free weight. Significant difference
(P 0.05):
*
from T1;
T2 vs. T3;
T1 vs.
T3 and T2 vs. T3.
§
Group by time interaction.
Maximal aerobic capacity and related
variables. Table 1 shows data by groups for
O2 max expressed in
liters per minute and milliliters per kilogram of body weight or FFW
per minute. The results showed that
O2 max decreased
significantly for all groups at each test period but was more
pronounced from T2 to T3. The same was true whether the data were
expressed in terms of liters per minute or milliliters per kilogram of
body weight or FFW per minute except for the H group from T1 to T2 for
O2 max expressed in
millilliters per kilogram of FFW per minute. Figure 1 graphically displays the
O2 max (in
ml · kg1 · min1)
for the H, M, and L groups compared with an estimated aging curve for
athletes and sedentary persons (19). Figure 1 clearly shows that the L
group decreased in
O2 max at a greater
rate from T2 to T3 than both the H and M groups.
O2 max) of older
endurance athletes who continued to train at a high (
), moderate
(
), or low intensity (
) after 10- and 20-yr follow-ups (present
study). Curves for athletes (
) and untrained healthy persons (
)
are cross-sectional norms from Heath et al. (9).
In contrast to the
O2 max data,
O2 pulse and
Emax
were maintained from T1 to T2 and then decreased significantly from T2
to T3 for all groups. HRmax showed
a consistent reduction (P 0.05)
from T1 to T2 and from T2 to T3 for both the H and M groups but was
maintained by the L group. Resting HR increased but remained low and
generally constant for all groups over the 20-yr follow-up (Table 1).
Two markers of relative effort on the treadmill test, the respiratory exchange ratio and RPE, are shown in Table 1. The respiratory exchange ratio from T1 to T2 and from T2 to T3 and the RPE from T2 to T3 did not change significantly over time for all groups. These data were clearly in the range that is reflective of a maximal effort.
Factors associated with change in aerobic
power. To gain insight on potential factors affecting
the change in
O2 max
(
O2 max), Table
2 presents data on age and
longitudinal differences (T1 to T2 and T2 to T3) of selected variables
and their relationship to the
O2 max described by
simple linear regression. To further assess these relationships,
multiple regression analyses were performed, with all variables entered
into the regression equation in one single block. In assessing the T1
to T2
O2 max, combining %fat,
Emax,
and O2 pulse increased the
correlation with
O2 max to
r = 0.93 (r2 = 0.86;
P 0.05). In assessing the T2 to T3
O2 max, combining age, pace,
Emax,
and O2 pulse increased the
correlation with O2 max to
r = 0.87 (r2 = 0.75;
P 0.05).
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Body composition and selected anthropometric data. The data for body composition and other selected anthropometric measures are shown in Table 3. Standing height was maintained from T1 to T2 for all groups and decreased slightly from T2 to T3 for the H and M groups. Total body weight remained constant over the 20-yr testing period for the H and M groups but increased significantly from T2 to T3 for the L group. Although the H and M groups remained lean over the 20-yr follow-up period, they significantly decreased their FFW from T1 to T2 and from T2 to T3 and increased their body fat over the same time periods. The FFW of the L group initially decreased from T1 to T2 but increased to their T1 values at T3. The apparent maintenance of FFW is deceptive in that the L group had increased their body weight by 6.3 kg and their body fat by 3.7% from T2 to T3.
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The waist circumference followed the same pattern of increase as found with body fat values and was particularly evident from T2 to T3 in the L group. In contrast, the hip, thigh, and biceps circumferences were generally maintained for all groups except for an increase in hip girth from T2 to T3 for the L group. Chest expansion was generally maintained by all groups over the 20-yr follow-up except for a significant decrease from T2 to T3 for the H group. Because there was no significant difference in chest expansion from T1 to T3 for the H group, the above-mentioned decrease from T2 to T3 was most likely reflective of the small increase found between T1 and T2.
Pulmonary function. Spirometry results (FEV1, FVC, and FEV1-to-FVC ratio) were available for 20 of 21 subjects from T1, T2, and T3. Mean values remained similar for all subjects and all groups from T1 to T2 (Table 4). At T3, a significant decline was observed in FEV1 and FVC. The greater decline in FVC compared with FEV1 resulted in a significant increase in the FEV1-to-FVC ratio at T3 compared with T2. Residual volume (RV), total lung capacity (TLC), and the RV-to-TLC ratio were determined in all subjects at T2 and T3. At T3, RV remained similar to T2 values, whereas TLC significantly declined. The decline in TLC resulted in a significant increase in the RV-to-TLC ratio.
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Cross-sectional data on strength and BMD at T3. The data for strength and BMD by age are shown in Table 5. The results show that leg strength was well maintained up to 79-89 yr and significantly reduced by age 90+. In contrast, lumbar extension peak torque was significantly lower at 79+ yr. There was a general trend for chest press strength to decline with each decade of age and particularly after 79 yr, but it was only significant at 90+ yr. All BMD measurements were generally maintained for all age groups 60-90+ yr except for the total body BMD value for 60-69 vs. 90+ yr.
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Resistance training. The subjects who reported participating regularly in weight training between T2 and T3 (n = 16) were compared at T3 with those who did not (n = 5). The data in Table 6 represent the changes in scores from T2 to T3 in selected variables. There was no significant difference between the groups in any of the selected variables.
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DISCUSSION
Aerobic capacity. Previous studies (2,
5, 9, 28, 29, 33) have shown a 5-15% reduction/decade in
O2 max for men
20-75 yr of age. Some have suggested that highly trained endurance athletes and average-trained fitness participants may have less than a
5% decline/decade in
O2 max if they
continue high-level training. In contrast, highly trained endurance
athletes who become sedentary have a greater than average reduction in
O2 max with age (5, 28, 33). Part of the disparity in reports of the change
and/or decline in
O2 max with age is
related to whether the data were reported from cross-sectional or
longitudinal studies. Dehn and Bruce (5) stated that the information
reported from longitudinal studies is more accurate. Cross-sectional
studies may represent a bias sample, generally including more fit
persons who are willing to volunteer and provide a maximal effort
during exercise testing (5).
Lifestyle or change in activity habits can significantly affect the
rate of decline in
O2 max with age (10,
11, 23). Jackson et al. (10), in a cross-sectional analysis of 1,499 healthy men 25-70 yr of age, found that
O2 max was lower in older groups and that age accounted for 50% of the variation
associated with self-reported physical activity index and percent fat
values. This was also confirmed in a 4.1-yr follow-up on a subsample of 156 men. Even so, the lack of reported information concerning activity
status of the various studies often makes longitudinal data difficult
to interpret.
Our present 20-yr follow-up data show average declines from T1 to T2
and from T2 to T3 of 8 and 15%, respectively, for the H group, 13 and
14%, respectively, for the M group, and 18 and 34%, respectively, for
the L group (Fig. 1). This may appear contradictory to the results of
the 10-yr follow-up by Pollock et al. (23) in which the H
group did not change in
O2 max. The earlier H group did not change its intensity and volume of exercise from T1 to
T2. The H group at T3 were different individuals who all had
significantly reduced their training intensity and mileage. Heath et
al. (9) averaged the
O2 max values from nine
different studies that included 563 sedentary healthy men and found a
decline in O2 max of
9%/decade. On the basis of the assumptions of Heath et al., aging
curves for active and sedentary men were developed and plotted in Figs.
1 and 2. It is obvious from Fig. 1 that our H and M groups followed a similar pattern of decline in
O2 max over the 20-yr
period of follow-up and had a slightly greater rate of decline than the
active persons' curve, particularly from T2 to T3 for the H group.
Even so, both the H and M groups were ranked above the 95th percentile
norm values compared with their age group. [Norms were based on
data from the Cooper Aerobic Center Longitudinal Study (CACLS) and
published by Pollock and Wilmore (26). Additional norms were provided
by Dr. Stephen Blair and Mark Harris of the CACLS for persons over 80 yr of age (personal communication)]. In addition, the H group was
able to maintain its elite status in national and international
competition in aerobic endurance events. It is clear that the
accelerated rate of decline in
O2 max from T2 to T3
(34%) for the L group was caused by a dramatic reduction in exercise
volume and training intensity.
O2 max of endurance
athletes and nonathletes of various ages. Data are from studies listed
(bottom).
Figure 2 summarizes the
O2 max values for
various groups of endurance athletes, nonathletic aerobic-fitness
participants, and sedentary men reported from various longitudinal
studies (2, 9, 11, 12, 17, 23, 28, 29, 33). Also plotted in Fig. 2 are cross-sectional data points for elite young distance runners (22) and a 70-yr-old world recordholder in the marathon (18).
Several important points can be gleaned from Fig. 2:
1) the rate of decline in
O2 max is not the same
for each study; 2) the rate of
decline in O2 max is
related to the initial level of aerobic power and a reduction in the
activity level of the active groups;
3)
O2 max remains
relatively constant over time if training status does not change; and
4) in most studies in which active
participants reduced their training level but still remained quite
active, O2 max declined
at a rate of 5-10%/decade.
In the 10-yr follow-up studies by Pollock et al. (23) on highly trained
endurance athletes and Kasch and Wallace (12) on average
aerobic-fitness-trained participants, no significant changes in
O2 max were observed.
These were the only studies listed in which training volume and
intensity did not change. It is quite evident from the present study
and the 22-yr follow-up by Trappe et al. (33) on endurance athletes and
by Kasch et al. (11) and Trappe et al. (33) on aerobic-fitness
participants that maintaining the volume and intensity of training over
periods of time longer than 10 yr is difficult and has not been
reported. Difficulty in maintaining a high level of training intensity
appears to be the case with both younger and older participants. It
appears from one study that increasing the volume of training may
offset the change in training intensity and lessen the decline in
O2 max (11). Whether
maintaining both the volume and intensity of training for 15 or more yr
would enable O2 max to
be maintained is not known.
Factors associated with change in aerobic
power. It is important to note that age and measures of
training intensity (pace and miles per week) were not well correlated
to the O2 max during
the first 10-yr period. Table 1 shows that the mean ages (60 yr) of the
groups were similar and training was relatively similar within groups
during the first 10-yr period. These data suggest that the age-related
decrement in O2 max can
be attenuated through middle age (i.e., to age 60 yr) if subjects
maintain similar levels of training activity (23). During the second
10-yr follow-up period, however, age and pace were significantly
correlated to the decline in
O2 max. These data
thus suggest that a critical interaction among age, level of physical
activity, and cardiopulmonary function occurs near age 65-70 yr,
resulting in a nonlinear change in aerobic power.
Changes in body composition appear to have important effects on the
age-associated decline in
O2 max. Jackson et al.
(10) reported that decreasing levels of physical activity and
increasing levels of percent fat accounted for nearly 50% of the
age-associated difference in
O2 max in men age
25-70 yr. However, the mean age of the subjects at a 4.1-yr
follow-up was 50 yr, so it is difficult to interpret how these effects
might differ in older participants. Fleg and Lakatta (6) reported that
a large portion (at least 50%) of the age-associated decline in
O2 max can be attributed to the loss in muscle mass in untrained men. In the present
study, changes in percent fat had a moderate correlation with
O2 max during the
first 10-yr period, but changes in body composition variables had
weaker correlations during the second 10-yr follow-up period (Table 2).
These data suggest that body composition changes may be less
influential after age 65-70 yr than the cardiopulmonary factors
associated with reduced training in the reduction in
O2 max in
endurance-trained subjects.
O2 pulse [an estimate of
stroke volume (3)] and
Emax
were highly correlated to
O2 max, whereas
HRmax was not. The HRmax declined ~5-7
beats · min1 · decade1,
and these data provide strong evidence that habitual physical training
does not maintain HRmax with
increasing age. However, these data also indicate that the effect of
HRmax on
O2 max may be highly
variable. The maintenance of O2
pulse at T2, followed by a significant decline at T3 (Table 1), and the
high correlation between
O2 pulse and
O2 max suggest that
moderate- to high-intensity physical training may prevent an
age-related decline in maximal stroke volume at least to approximately
age 60 yr. This effect (and/or the muscle's ability to extract
O2, which was not assessed in this
study) might then attenuate the effect of decrements in HRmax on
O2 max.
Similar to O2 pulse,
Emax
was maintained at T2 but significantly declined at T3 (Table 1). These
data and the moderate correlations observed between
Emax
and O2 max suggest
that moderate- to high-intensity physical training may prevent an
age-related decline in
Emax
at least to approximately age 60 yr. The large decline in
Emax
at T3 averaged 
19 to 22% and was similar to or less than
the decline reported by Trappe et al. (33) for highly
trained younger subjects (20%) and fitness-trained older runners (>50 yr, 30%).
Little information is available concerning the role of pulmonary
function changes in the decline of
O2 max in
endurance-trained athletes. Studies report that most age-associated
physiological changes in resting lung function can be attributed to the
mechanics of ventilation, i.e., a decrease in chest wall and pulmonary
com
7 Skinfolds, mm