Journal of Applied Physiology
Vol. 82, No. 5, pp. 1508-1516, May 1997
EXERCISE AND MUSCLE

Twenty-year follow-up of aerobic power and body composition of older track athletes

Michael L. Pollock, Larry J. Mengelkoch, James E. Graves, David T. Lowenthal, Marian C. Limacher, Carl Foster, and Jack H. Wilmore

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 · min¹ · 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 (O_{2 max}), pulmonary ventilation (E_max), and heart rate (HR_max) 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 O_{2 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 O_{2 max} with age will be 5%/decade.

Although it has been suggested that the slopes of the regression in O_{2 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 O_{2 max} are greatly affected by the initial level of aerobic capacity and change in activity status (5, 23, 26, 28).

A reduction in HR_max with age has been shown to be linear, with an ~10 beat · min¹ · 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 HR_max 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).

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% HR_max reserve. In addition, they performed an interval session or aerobic threshold training session (85% HR_max 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% HR_max reserve. These subjects only occasionally competed. The L group changed their mode of activity from running to walking. Their usual training intensity was 70% HR_max 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).

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 (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).

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 · kg¹ · min¹; P  0.05), and the highest value attained for each subject was used to determine O_{2 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.

At T1 and T3, O_{2 max} was determined by the Douglas bag method. At T2, O_{2 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).

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  0.05.

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  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).

Table 1. Training data and metabolic measurements 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 · kg1 · 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 FFW1 · 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 O_{2 max} expressed in liters per minute and milliliters per kilogram of body weight or FFW per minute. The results showed that O_{2 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 O_{2 max} expressed in millilliters per kilogram of FFW per minute. Figure 1 graphically displays the O_{2 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 O_{2 max} at a greater rate from T2 to T3 than both the H and M groups.

In contrast to the O_{2 max} data, O₂ pulse and E_max were maintained from T1 to T2 and then decreased significantly from T2 to T3 for all groups. HR_max 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 O_{2 max} (O_{2 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 O_{2 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 O_{2 max}, combining %fat, E_max, and O₂ pulse increased the correlation with O_{2 max} to r = 0.93 (r² = 0.86; P  0.05). In assessing the T2 to T3 O_{2 max}, combining age, pace, E_max, and O₂ pulse increased the correlation with O_{2 max} to r = 0.87 (r² = 0.75; P  0.05).

Table 2. Longitudinal changes among all subjects of selected variables and simple linear regression model of relationship with O2 max Age, yr  O2 max, ml · kg1 · min1  %Fat, skinfolds  FFW, kg  Mileage, miles/wk  Pace, min/miles  Emax, l/min BTPS  HRmax, beats/min  O2 Pulse, ml/beats T1 to T2 Mean ± SD 60.2 ± 8.8   4.2 ± 4.5  2.5 ± 1.6   2.4 ± 1.2   5.7 ± 0.4  0.68 ± 0.93  8.4 ± 14.4   7 ± 6   1.1 ± 1.6  r 0.07 1.0 0.52* 0.16 0.02 0.32 0.50* 0.15 0.88* T2 to T3 Mean ± SD 70.4 ± 8.8   9.6 ± 4.6  2.4 ± 2.2   0.5 ± 1.9   8.9 ± 10.0  1.82 ± 2.30   34.0 ± 14.9   6 ± 7   3.0 ± 2.3  r 0.45* 1.0 0.29 0.01 0.08 0.56* 0.56* 0.08 0.85* n = 21 subjects except n = 20 subjects for longitudinal change () from T1 to T2 Emax. Ages are for subjects at T2 and T3. * P  0.05.

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.

Table 3. Anthropometric measurements 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 Height, cm 177.4 ± 5.9  176.6* ± 6.2  175.8 ± 6.5  175.6 ± 5.6  175.5 ± 6.0  174.5 ± 6.6  179.6 ± 6.2  178.2* ± 6.9  177.6* ± 7.0  174.3 ± 2.2  173.4 ± 1.6  173.1 ± 0.5  Weight, kg 70.1 ± 7.8  69.4 ± 8.2  70.8 ± 8.8  66.3 ± 5.7  65.3 ± 5.9  65.8 ± 5.2  72.3 ± 8.9  71.9 ± 9.3  73.1 ± 9.6  75.9 ± 1.7  75.2 ± 3.0  81.5 ± 0.1  FFW, kg 61.4 ± 6.2  59.1 ± 6.2  58.6§ ± 6.5  59.5 ± 5.1  57.0* ± 5.0  55.7 ± 4.7  62.7 ± 7.5  60.4* ± 7.4  60.0* ± 7.6  63.9 ± 0.6  61.6* ± 1.9  63.7 ± 0.6   7 Skinfolds, mm 66.9 ± 25.8  75.2* ± 25.6  82.6 ± 26.3  53.7 ± 12.7  61.8 ± 15.8  70.6* ± 19.9  74.5 ± 31.4  83.3 ± 29.8  87.7* ± 28.7  88.0 ± 5.7  95.0 ± 7.1  111.5* ± 6.4  %Fat, skinfolds 12.2 ± 4.2  14.6* ± 4.2  17.1 ± 4.2  10.2 ± 2.1  12.7* ± 2.6  15.3 ± 2.9  13.2 ± 5.3  15.8* ± 5.0  17.7 ± 4.8  15.7 ± 1.1  18.1 ± 0.8  21.8 ± 0.6  Waist girth, cm 80.0 ± 6.0  82.4* ± 6.5  85.4 ± 7.3  76.3 ± 3.9  79.3* ± 5.0  81.2* ± 5.5  83.1 ± 6.5  84.3* ± 7.4  87.4 ± 7.1  82.7 ± 0.7  86.6 ± 0.2  94.6 ± 3.3  Hip girth, cm 93.6 ± 3.9  92.1* ± 4.0  92.9 ± 3.8  91.7 ± 3.5  90.5 ± 3.6  90.9 ± 2.2  94.6 ± 3.7  92.9 ± 4.0  93.6 ± 3.8  97.8 ± 2.2  95.8 ± 1.4  98.6 ± 2.8  Thigh girth, cm 54.1 ± 3.8  54.3 ± 3.1  53.5 ± 3.3  54.1 ± 3.8  54.1 ± 2.9  52.3 ± 2.4  55.0 ± 4.6  54.4 ± 3.6  53.8 ± 3.6  57.5 ± 1.8  54.9 ± 1.8  57.8 ± 0.8  Biceps girth, cm 30.5 ± 2.2  30.5 ± 2.3  30.7 ± 2.4  29.2 ± 1.7  29.3 ± 1.5  29.2 ± 1.5  31.2 ± 1.9  31.0 ± 2.4  31.3 ± 2.2  33.9 ± 0.2  33.2 ± 1.0  34.8 ± 0.8  Chest expansion girth, cm 7.3 ± 1.8  7.8 ± 1.4  7.1 ± 1.8  7.0 ± 1.5  7.8 ± 1.2  6.7 ± 1.5  7.2 ± 1.7  7.5 ± 1.3  7.2 ± 1.9  9.1 ± 3.8  9.7 ± 1.3  7.9 ± 3.1 Values are means ± SD; n, no. of subjects except n = 20 for all subjects and 9 for moderate-intensity group T1 waist girth and hip girth, n = 19 for all subjects and 8 for moderate-intensity group T1 thigh girth and biceps girth, and n = 18 for all subjects and 8 each for high- and moderate-intensity group T1 chest expansion girth. Significant difference (P  0.05): * from T1; T2 vs. T3; T1 vs. T3 and T2 vs. T3. § Group by time interaction.

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.

Table 4. Changes in pulmonary function All Subjects High-Intensity Group Moderate-Intensity Group Low-Intensity Group T1 T2 T3 T1 T2 T3 T1 T2 T3 T1 T2 T3 n 20 20 20 9 9 9 10 10 10 1 1 1 FEV1, liters 3.906 ± 0.559  3.840 ± 0.619  3.392 ± 0.627  3.742 ± 0.467  3.656 ± 0.499  3.282 ± 0.498  4.013 ± 0.640  3.971 ± 0.721  3.469 ± 0.764  4.313 ± 0  4.190 ± 0  3.620* ± 0  FVC, liters 5.187 ± 0.848  5.248 ± 0.742  4.376 ± 0.692  4.980 ± 0.459  5.009 ± 0.579  4.211 ± 0.591  5.445 ± 1.080  5.447 ± 0.872  4.527 ± 0.806  5.289 ± 0  5.420 ± 0  4.340 ± 0  FEV1/FVC, %  76 ± 6  73 ± 7  78 ± 6  77 ± 6  73 ± 7  78 ± 6  74 ± 5  73 ± 7  76 ± 7  82 ± 0  77 ± 0  83 ± 0  RV, liters 2.514 ± 0.426  2.530 ± 0.469  2.365 ± 0.384  2.463 ± 0.403  2.507 ± 0.347  2.416 ± 0.326  3.217 ± 0.428  3.403 ± 0.675  TLC, liters 7.712 ± 0.974  6.838 ± 0.885  7.374 ± 0.778  6.674 ± 0.750  7.954 ± 1.115  6.943 ± 1.047  8.335 ± 0  7.265 ± 0  RV/TLC, %  32 ± 3  36 ± 4  32 ± 4  37 ± 3  32 ± 3  35 ± 3  35 ± 0  40 ± 0 Values are means ± SD; n, no. of subjects except n = 21 for all subjects and 2 for low-intensity group residual volume (RV). FEV1, forced expiratory volume in 1 s; FVC, forced vital capacity; TLC, total lung capacity. Significant difference (P  0.05): * from T1; T2 vs. T3; T1 vs. T3 and T2 vs. T3.

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.

Table 5. Cross-sectional strength and bone mineral density data by age at T3 Total Group n 60-69 yr n 70-78 yr n 79-89 yr n 90+ yr n Leg press 1 RM, kg 120.7 ± 32.9  21 134.4 ± 29.3  9 126.4 ± 9.7  5 126.7 ± 21.9  4 62.1 ± 17.2 3 Chest press 1 RM, kg 54.9 ± 17.1  22 65.4 ± 13.5  9 57.6 ± 14.3  6 44.9 ± 12.4  4 31.0 ± 5.7* 3 Lumbar peak torque, N · m 292.2 ± 58.0  22 326.4 ± 50.0 10 297.8 ± 50.0  5 234.6 ± 28.1  4 245.4 ± 45.4  3 Bone mineral density, g/cm2   L2 1.126 ± 0.119  23 1.163 ± 0.134  10 1.082 ± 0.131  6 1.098 ± 0.066  4 1.128 ± 0.115  3   L3 1.181 ± 0.125  23 1.177 ± 0.132  10 1.186 ± 0.147  6 1.190 ± 0.120  4 1.174 ± 0.126  3   L1-4 1.148 ± 0.112  23 1.157 ± 0.132  10 1.124 ± 0.127  6 1.154 ± 0.085  4 1.157 ± 0.075  3   Total body 1.185 ± 0.050  23 1.203 ± 0.057  10 1.185 ± 0.022  6 1.182 ± 0.046  4 1.129 ± 0.041* 3   Trochanter 0.859 ± 0.103  23 0.888 ± 0.117  10 0.839 ± 0.105  6 0.834 ± 0.051  4 0.837 ± 0.133  3 Values are means ± SD; n, no. of subjects. 1 RM, 1 repetition maximum. Of 23 subjects evaluated for bone mineral density, two 90+ yr subjects were evaluated only at T3. Significant difference (P  0.05): * 90+ yr vs. 60-69 yr; 90+ yr vs. 69-69 yr, 70-78, and 79-89 yr; 60-69 yr vs. 79-89 and 90+ yr.

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.

Table 6. Comparison of subjects who reported regular resistance exercise training at T3 with longitudinal changes from T2 to T3 n Age, yr  Weight, kg  FFW, kg  %Fat, skinfolds  Chest Expansion Girth, cm  Biceps Girth, cm  Thigh Girth, cm  O2 max, ml · kg1 · min1 Resistance and aerobic 16 70.3 ± 9.6  0.6 ± 3.9   0.4 ± 2.1  2.3 ± 2.3   0.6 ± 1.2  0.4 ± 1.1   0.06 ± 3.0   9.9 ± 5.1  Aerobic 5 71.0 ± 6.4  0.9 ± 3.1   1.0 ± 1.0  2.9 ± 2.0   1.3 ± 0.8   0.2 ± 0.9   1.4 ± 1.6   8.9 ± 2.9 Values are means ± SD; n, no. of subjects. No significant differences were found between groups.

DISCUSSION

Aerobic capacity. Previous studies (2, 5, 9, 28, 29, 33) have shown a 5-15% reduction/decade in O_{2 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 O_{2 max} if they continue high-level training. In contrast, highly trained endurance athletes who become sedentary have a greater than average reduction in O_{2 max} with age (5, 28, 33). Part of the disparity in reports of the change and/or decline in O_{2 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 O_{2 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 O_{2 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 O_{2 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 O_{2 max} values from nine different studies that included 563 sedentary healthy men and found a decline in O_{2 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 O_{2 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 O_{2 max} from T2 to T3 (34%) for the L group was caused by a dramatic reduction in exercise volume and training intensity.

Figure 2 summarizes the O_{2 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 O_{2 max} is not the same for each study; 2) the rate of decline in O_{2 max} is related to the initial level of aerobic power and a reduction in the activity level of the active groups; 3) O_{2 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, O_{2 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 O_{2 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 O_{2 max} (11). Whether maintaining both the volume and intensity of training for 15 or more yr would enable O_{2 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 O_{2 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 O_{2 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 O_{2 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 O_{2 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 O_{2 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 O_{2 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 O_{2 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 O_{2 max} in endurance-trained subjects.

O₂ pulse [an estimate of stroke volume (3)] and E_max were highly correlated to O_{2 max}, whereas HR_max was not. The HR_max declined ~5-7 beats · min¹ · decade¹, and these data provide strong evidence that habitual physical training does not maintain HR_max with increasing age. However, these data also indicate that the effect of HR_max on O_{2 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 O_{2 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 HR_max on O_{2 max}.

Similar to O₂ pulse, E_max was maintained at T2 but significantly declined at T3 (Table 1). These data and the moderate correlations observed between E_max and O_{2 max} suggest that moderate- to high-intensity physical training may prevent an age-related decline in E_max at least to approximately age 60 yr. The large decline in E_max 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 O_{2 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 compliance and a decrease in respiratory muscle strength (19). We attempted to determine whether changes in resting lung function and an indirect measurement of chest wall and pulmonary compliance (circumference measurement of chest expansion) were correlated to E_max. As shown in Tables 3 and 4, significant changes in chest expansion and resting lung function were not observed until T3. These data suggest that moderate- to high-intensity physical training may prevent an age-related decline in resting lung function at least to approximately age 60 yr. These data are in agreement with McClaran et al. (19), who suggested that nonlinear changes in resting lung function in fit elderly adults likely occur near age 65-70 yr. With the use of simple regression analyses, the E_max (T2 to T3) was only significantly correlated with the TLC (r = 0.44) and pace (r = 0.50) but not with the chest expansion or the changes in other lung function measurements. Because hyperpnea is an effective training method for respiratory muscle endurance training (15), it is interesting to speculate that changes in pace and its association with hyperpnea and respiratory muscle endurance, as well as changes in lung volume, may have important effects on age-related changes in E_max.

1

1

1

1

1

1

1

1

1

1

1

1

ACKNOWLEDGEMENTS

The authors acknowledge Linda Martin for typing skills and Linda Garzarella for technical assistance in preparing the tables and figures for this manuscript.

FOOTNOTES

Address for reprint requests: M. L. Pollock, Univ. of Florida, Dept. of Medicine, PO Box 100277, Gainesville, FL 32610.

Received 25 June 1996; accepted in final form 23 December 1996.

REFERENCES

1.	American Thoracic Society Standardization of spirometry1987 update. Am. Rev. Respir. Dis. 136: 1285-1298, 1987. [Medline]
2.	Astrand, I., P. O. Astrand, I. Hallback, and A. Kilbom. Reduction in maximal oxygen uptake with age. J. Appl. Physiol. 35: 649-654, 1973. [Free Full Text]
3.	Bhambhami, Y., S. Norris, and G. Bell. Prediction of stroke volume from oxygen pulse measurements in untrained and trained men. Can. J. Appl. Physiol. 19: 49-59, 1994. [Medline]
4.	Borg, G., and H. Linderholm. Perceived exertion and pulse rate during graded exercise in various age groups. Acta Med. Scand. 472: 194-206, 1967.
5.	Dehn, M. M., and R. A. Bruce. Longitudinal variations in maximal oxygen intake with age and activity. J. Appl. Physiol. 33: 805-807, 1972. [Free Full Text]
6.	Fleg, J. L., and E. G. Lakatta. Role of muscle loss in the age-associated reduction in O2 max. J. Appl. Physiol. 65: 1147-1151, 1988 [Abstract/Free Full Text] .
7.	Forbes, G. B. The adult decline in lean body mass. Hum. Biol. 48: 161-173, 1976. [Medline]
8.	Golding, L. A., C. R. Myers, and W. E. Sinning. Y's Way to Physical Fitness (3rd ed.). Champaign, IL: Human Kinetics, 1989, p. 125-130.
9.	Heath, G. W., J. M. Hamberg, A. A. Ehsani, and J. O. Holloszy. A physiological comparison of young and older endurance athletes. J. Appl. Physiol. 51: 634-640, 1981. [Abstract/Free Full Text]
10.	Jackson, A. S., E. F. Beard, L. T. Wier, R. M. Ross, J. E. Stuteville, and S. N. Blair. Changes in aerobic power of men, ages 25-70 yr. Med. Sci. Sports Exercise 27: 113-120, 1995 [Medline] .
11.	Kasch, F. W., J. L. Boyer, S. VanCamp, F. Nettl, L. S. Verity, and J. R. Wallace. Cardiovascular changes with age and exercise: a 28-year longitudinal study. Scand. J. Med. Sci. Sports 5: 147-151, 1995 [Medline] .
12.	Kasch, F., and J. P. Wallace. Physiological variables during 10 years of endurance exercise. Med. Sci. Sports 8: 5-8, 1976 [Medline] .
13.	Lane, N. E., D. A. Bloch, H. H. Jones, W. H. Marshall, P. D. Wood, and J. F. Fries. Long-distance running, bone density, and osteoarthritis. JAMA 255: 1147-1151, 1986 [Abstract/Free Full Text] .
14.	Larsson, L., G. Grimby, and J. Karlsson. Muscle strength and speed of movement in relation to age and muscle morphology. J. Appl. Physiol. 46: 451-456, 1979. [Abstract/Free Full Text]
15.	Leith, D. E., and M. Bradley. Ventilatory muscle strength and endurance training. J. Appl. Physiol. 41: 508-516, 1976. [Abstract/Free Full Text]
16.	Londeree, B. R., and M. L. Moeschberger. Effect of age and other factors on maximal heart rate. Res. Q. Exercise Sport 53: 297-304, 1982.
17.	Marti, B., and H. Howland. Long-term effects of physical training on aerobic capacity: controlled study of former elite athletes. J. Appl. Physiol. 69: 1451-1459, 1990 [Abstract/Free Full Text] .
18.	Maud, P. J., M. L. Pollock, C. Foster, J. Anholm, G. Guten, M. Al-Nouri, C. Hellman, and D. H. Schmidt. Fifty years of training and competition in the marathon: Wally Hayward aged 70a physiological profile. S. Afr. Med. J. 59: 153-157, 1981 [Medline] .
19.	McClaran, S. R., M. A. Babcock, D. F. Pegelow, W. G. Reddan, and J. A. Dempsey. Longitudinal effects of aging on lung function at rest and exercise in healthy active fit elderly adults. J. Appl. Physiol. 78: 1957-1968, 1995 [Abstract/Free Full Text] .
20.	Montoye, H. J. The 1987 C. H. McCloy Research Lecture Better Bones and Biodynamics. Res. Q. Exercise Sport 58: 334-348, 1987.
21.	Montoye, H. J., E. L. Smith, D. F. Fardon, and E. T. Howley. Bone mineral in senior tennis players. Scand. J. Sports Sci. 2: 26-32, 1980.
22.	Pollock, M. L. Submaximal and maximal working capacity of elite distance runners. Ann. NY Acad. Sci. 301: 310-322, 1977 [Medline] .
23.	Pollock, M. L., C. Foster, D. Knapp, J. L. Rod, and D. H. Schmidt. Effect of age and training on aerobic capacity and body composition of master athletes. J. Appl. Physiol. 62: 725-731, 1987 [Abstract/Free Full Text] .
24.	Pollock, M. L., L. R. Gettman, A. Jackson, J. Ayres, A. Ward, and A. C. Linnerud. Body composition of elite class distance runners. Ann. NY Acad. Sci. 301: 361-370, 1977 [Medline] .
25.	Pollock, M. L., H. S. Miller, and J. H. Wilmore. Physiological characteristics of champion American track athletes 40-75 years of age. J. Gerontol. 29: 645-649, 1974 .
26.	Pollock, M. L., and J. H. Wilmore. Exercise in Health and Disease: Evaluation and Prescription for Prevention and Rehabilitation (2nd ed.). Philadelphia, PA: Saunders, 1990, p. 128-138, 319-348, 660-665.
27.	Porter, M. M., A. A. Vandervoort, and J. Lexell. Aging of human muscle: structure, function and adaptability. Scand. J. Med. Sci. Sports 5: 129-142, 1995 [Medline] .
28.	Robinson, S., D. B. Dill, R. D. Robinson, S. P. Tzankoff, and J. A. Wagner. Physiological aging of champion runners. J. Appl. Physiol. 41: 46-51, 1976. [Abstract/Free Full Text]
29.	Rogers, M. A., J. M. Hagberg, W. H. Martin, A. A. Ehsani, and J. O. Holloszy. Decline in O2 max with aging in master athletes and sedentary men. J. Appl. Physiol. 68: 2195-2199, 1990 [Abstract/Free Full Text] .
30.	Sandler, R. B., R. Burdett, M. Zaleskiewicz, C. Sprowls-Repcheck, and M. Harwell. Muscle strength as an indicator of the habitual level of activity. Med. Sci. Sports Exercise 23: 1375-1381, 1991 [Medline] .
31.	Suominen, H. Bone mineral density and long term exercise: an overview of cross-sectional athlete studies. Sports Med. 16: 316-330, 1993 [Medline] .
32.	Suominen, H., and P. Rahkila. Bone mineral density of the calcaneus in 70- to 81-yr-old male athletes and population sample. Med. Sci. Sports Exercise 23: 1227-1233, 1991 [Medline] .
33.	Trappe, A. W., D. L. Costill, M. D. Vukovich, J. Jones, and T. Melhom. Aging among elite distance runners: a 22-yr longitudinal study. J. Appl. Physiol. 80: 285-290, 1996. [Abstract/Free Full Text]