 |
|
Improved Cardiorespiratory Endurance Following 6 Months of Resistance Exercise in Elderly Men and Women
Kevin R. Vincent, PhD;
Randy W. Braith, PhD;
Ross A. Feldman, MS;
Henrique E. Kallas, MD;
David T. Lowenthal, MD, PhD
Arch Intern Med. 2002;162:673-678.
ABSTRACT
| |
Objective To examine the effect of 6 months of high- or low-intensity resistance
exercise on aerobic capacity and treadmill time to exhaustion in adults aged
60 to 83 years.
Methods Sixty-two men and women completed the study protocol. Subjects were
matched for strength and randomly assigned to a control (n = 16), low-intensity
exercise (LEX, n = 24), or high-intensity exercise (HEX, n = 22) group. Subjects
trained at either 50% of their one repetition maximum (1-RM) for 13 repetitions
(LEX) or 80% of 1-RM for 8 repetitions (HEX) 3 times per week for 24 weeks.
One set each of 12 exercises was performed. Strength was measured for the
leg press, chest press, leg curl, leg extension, overhead press, biceps curl,
seated row, and triceps dip. Muscular endurance was measured for the leg press
and chest press. Aerobic capacity (peak oxygen consumption [ O2peak]) was measured during an incremental treadmill test (Naughton).
Treadmill time to exhaustion was measured as the time to exhaustion during
the incremental exercise test.
Results The 1-RM significantly increased (P .05)
for all exercises tested for both the HEX and LEX groups. Aerobic capacity
increased (P.05) by 23.5% (20.2 to 24.7 mL ·
kg-1· min-1) and by 20.1% (20.9 to
24.4 mL · kg-1· min-1) for
the LEX and HEX groups, respectively. Treadmill time increased (P.05) by 26.4% and 23.3% for the LEX and HEX groups, respectively.
Conclusions Significant improvements in aerobic capacity and treadmill time to exhaustion
can be obtained in older adults as a consequence of either high- or low-intensity
resistance exercise. These findings suggest that increased strength, as a
consequence of resistance exercise training, may allow older adults to reach
and/or improve their aerobic capacity.
INTRODUCTION
CARDIORESPIRATORY fitness, measured as maximum oxygen consumption (O2max) or peak oxygen consumption (O2peak), is related
to all-cause mortality.1 Specifically, reduced
cardiorespiratory fitness is associated with increased risk of cardiovascular
disease, stroke, hypertension, and mortality.2-5
Interventions that improve cardiorespiratory endurance can have important
health implications by decreasing the probability of disease, disability,
and mortality.1, 6
Endurance exercise is traditionally viewed as the primary means of increasing
aerobic capacity.7 Resistance exercise, in
contrast, is not typically viewed as a means for improving cardiorespiratory
endurance.8-10
Indeed, studies11-12 of young
and middle-aged subjects using traditional resistance exercise regimens consisting
of multiple sets and long rest periods (>2 minutes) have failed to demonstrate
significant improvements in aerobic capacity. The absence of cardiorespiratory
adaptation may be explained by the fact that a session of resistance exercise
has been shown to correspond to an oxygen uptake of only 36% to 45% of O2max.13-14 These values
are lower than what is commonly recommended to elicit improvements in aerobic
capacity.7 An alternative explanation is that
augmentation of peripheral skeletal muscle strength does not influence cardiorespiratory
performance in young and middle-aged individuals because they possess normal
leg strength values.
Recent reports15-17
from several laboratories suggest that the measurement of aerobic capacity
in elderly subjects may be compromised by skeletal muscle weakness and strength
loss. Flegg and Lakatta16 suggested that the
age-related decline in aerobic capacity can be explained in part by decreased
muscle mass. Frontera et al18 observed increases
in O2max (when expressed as mL · kgFFM-1· min-1) (FFM indicates fat free mass) following
12 weeks of resistance training in the elderly. In addition to strength gains,
the authors reported that the aerobic adaptations were accompanied by increased
capillary density and citrate synthase activity.18
To date, however, no studies have been specifically designed to assess aerobic
adaptations during a traditional, total body resistance exercise regimen in
an elderly population.
Accordingly, the purpose of this study was to measure aerobic power
in subjects 60 to 85 years of age before and after 6 months of resistance
exercise training. We hypothesized that a traditional resistance exercise
regimen consisting of single sets and long rest periods (2 minutes) could
elicit increases in aerobic capacity and endurance in elderly people. In an
attempt to determine the quantity of resistance exercise necessary to elicit
aerobic adaptations, we trained our elderly subjects at both low and high
intensity.
SUBJECTS, MATERIALS, AND METHODS
SUBJECTS
Eighty-four apparently healthy adults between the ages of 60 and 83
years volunteered to participate in a 6-month training study. Sixty-two of
the volunteers completed the study protocol. Only subjects who had not participated
in regular resistance training for at least 1 year, but may have engaged in
low-intensity aerobic training equal to or less than 3 times per week were
eligible. Subjects also had to be free from any orthopedic or cardiovascular
problems that would limit exercise.
GROUP ASSIGNMENTS
After baseline testing, the subjects were rank ordered by composite
strength (one repetition maximum [1-RM] chest press plus 1-RM leg press) and
randomly stratified to 1 of the 2 training groups or a control group that
did not train. Subjects were randomly assigned to the control, low-intensity
exercise (LEX), or high-intensity exercise (HEX) groups using a random numbers
table. To be considered compliant and remain in the study, subjects had to
attend more than 85% of the possible exercise sessions. All subjects received
a comprehensive explanation of the proposed study, its benefits, its inherent
risks, and the expected commitments with regard to time. Following the explanation,
all subjects signed an informed consent document approved by the Institutional
Review Board at the University of Florida and in adherence with the guidelines
of the American College of Sports Medicine, Indianapolis, Ind.
MUSCLE STRENGTH ASSESSMENT
Dynamic muscular strength was measured using the following 8 resistance
exercises: leg press, leg curl, knee extension, chest press, seated row, overhead
press, triceps dip, and biceps curl. For each dynamic exercise, a 1-RM was
determined. A detailed description of the 1-RM testing procedure can be found
elsewhere.19 In brief, the subject began the
test by lifting a light weight and incremental increases were then made according
to the difficulty with which the subject executed the previous lift. The investigator
continued to increase the weight lifted until reaching the maximum weight
that could be lifted in 1 repetition with proper form. Maximal strength was
defined as the maximum weight that could be lifted through a full range of
motion with proper form.
AEROBIC POWER ASSESSMENT
The subject performed a walking symptom-limited graded exercise test
(GXT) using an incremental treadmill exercise protocol (Naughton) to determine
O2peak. The initial workload was 2.0 mph at 0% grade,
and the workload progressed every 2 minutes by increasing the grade 3.5%.
Once the test time reached 12 minutes, the treadmill speed increased to 3.0
mph and the incline decreased to a 12% grade. From this point, the grade again
increased 3.5% every 2 minutes until the subject reached voluntary maximal
exertion or became symptomatic with positive hemodynamic or medical indexes.20 The following criteria recommended by the American
College of Sports Medicine were used for termination of the symptom-limited
GXT.20 During the test, expired gases were
collected through a low-resistance 1-way valve (Hans Rudolph, Inc, Kansas
City, Mo). Breath-by-breath analysis of expired gases was performed continuously
throughout the test using a metabolic cart (CPS/Max; Medical Graphics, St
Paul, Minn). The oxygen and carbon dioxide analyzers were calibrated daily
and immediately before and after each test using a known gas mixture of 12%
oxygen and 5% carbon dioxide. Ventilatory responses (tidal volume and frequency
of breathing) were measured with a pneumotachograph. Volume calibration was
performed with a 3-L calibration syringe. Twelve-lead electrocardiograms were
recorded throughout the test using standard lead placement (Quinton Q 2000
system; Quinton Instruments, Seattle, Wash). Blood pressure measurements were
taken every other minute using a standard sphygmomanometer, and rating of
perceived exertion was obtained at the end of each minute throughout the test
using the Borg Scale of Perceived Exertion, a 6 (no exertion at all) to 20
(maximal exertion) point rated scale.
RESISTANCE EXERCISE TRAINING
The exercise training regimen is described in detail elsewhere.19 In brief, the exercise training equipment used in
this investigation was MedX resistance machines (MedX Corp, Ocala, Fla). The
machines used for this study were abdominal crunch, leg press, leg extension,
leg curl, calf press, seated row, chest press, overhead press, biceps curl,
seated dip, leg abduction, leg adduction, and lumbar extensions.
Subjects in both the LEX and HEX groups were asked to report to the
training facility 3 times per week for 6 months to perform dynamic variable
resistance exercise. Each set consisted of 8 repetitions for the HEX group
and 13 repetitions for the LEX group at the appropriate resistance load. To
examine the effects of training intensity on the outcome variables and criterion
measures, the LEX group trained at an intensity equivalent to 50% of their
1-RM, whereas the HEX group used loads corresponding to 80% of their 1-RM.
For the LEX and HEX groups, the load was increased by 5% when their rating
of perceived exertion dropped below 18. All exercise sessions were supervised
by trained study personnel, and all resistance loads were evaluated and adjusted
daily.
STATISTICAL ANALYSES
Statistical analyses were performed using the Statistical Package for
the Social Sciences software, version 9.0 (SPSS Inc, Chicago, Ill). Experimental
analysis was performed with a 3 x 2 repeated-measures analysis of variance
(ANOVA) model to determine differences within and between groups over time.
If a significant (group-by-time) interaction was found, a Scheffé post
hoc test was used to determine if and where there was a difference between
the group means. Although no statistical differences were observed between
groups at study entry, an analysis of covariance (ANCOVA) was performed on
outcome variables at the conclusion of the study. When the ANCOVA revealed
that the covariate significantly contributed to the outcome, then the predicted
means generated by the ANCOVA were analyzed with a 1-way ANOVA and a Scheffé
post hoc test. Pearson bivariate correlations were performed to examine the
degree of association between variables. A priori  levels were set
at .05.
RESULTS
SUBJECTS
Sixty-two of the original 84 subjects completed the study (controls
= 16, LEX = 24, HEX = 22). Of the 22 who did not finish, 11 were dropped by
the investigators for not adhering to the training protocol or dropped out
voluntarily for reasons of inconvenience. The other 11 dropped out because
of one of the following reasons: moved out of the area, financial difficulties,
or surgery or injury not related to the study protocol. Six of the training
subjects experienced joint discomfort (3 had pain in the knee, 2 suffered
soreness in the back, and 1 encountered pain in the elbow) and had to reduce
training for 2 weeks. The 6 subjects were distributed as follows: one of the
subjects who had knee pain and one who suffered back soreness were assigned
to the LEX group, and 2 subjects who experienced knee pain, 1 who suffered
back soreness, and 1 who encountered pain in the elbow were assigned to the
HEX group. Only subjects who completed both prestudy and poststudy testing
sessions and more than 85% of the possible exercise sessions were included
in the statistical analysis. Characteristics of those subjects who completed
the study are listed by group in Table 1. There were no statistically significant differences among groups
for age, height, and weight either before or after the study.
|
|
|
|
Table 1. Subject Characteristics*
|
|
|
MUSCULAR STRENGTH
A detailed description of the results for muscular strength changes
can be found elsewhere.19 Muscle strength did
not differ among groups at study entry. The percent changes for muscular strength
are shown in Table 2. Muscular
strength significantly increased in both training groups, ranging from 10.8%
to 25.3% and from 14.6% to 27.6% for the LEX and HEX groups, respectively.
Total strength values, calculated by summing the 1-RM values from the 8 tested
exercises, increased significantly from pretraining to posttraining (P.05), but were not different between the 2 training
groups (17.2% and 17.8% for the LEX and HEX groups, respectively).
|
|
|
|
Table 2. Percent Change in One Repetition Maximum Values Before and
After 6 Months of Resistance Training*
|
|
|
OXYGEN CONSUMPTION
Absolute values for O2peak are presented in Table 1. O2peak did
not differ among groups at study entry. O2peak significantly
increased as a consequence of resistance training from 20.2 to 24.7 mL ·
kg-1· min-1and from 20.9 to 24.4
mL · kg-1· min-1for the LEX
and HEX groups, respectively (P.05). The percent
changes for O2peak are shown in Figure 1. Both the LEX (23.5%) and HEX (20.1%) groups significantly
increased their O2peak during the 6 months of resistance
exercise (P .05). However, O2peak in the control group did not change.
TREADMILL TIME TO EXHAUSTION
Treadmill time to exhaustion during the GXT is presented in Table 1 and Figure 2. The control, LEX, and HEX groups increased treadmill time
by 6.2%, 26.4%, and 23.3%, respectively. However, only the LEX and HEX groups
significantly increased their treadmill time from pretraining to posttraining
(P.05).
|
|
|
|
Figure 2. Percent change in treadmill time
during a graded exercise test for the control (n = 16), low-intensity exercise
(LEX, n = 24), and high-intensity exercise (HEX, n = 22) groups following
6 months of resistance exercise training. Asterisk indicates P.05
from corresponding percent change in the control group. Error bars signify
SEM.
|
|
|
CORRELATIONS BETWEEN STRENGTH, O2peak, AND TREADMILL
TIME
Correlation coefficients between O2peak and muscular
strength are shown in Table 3.
O2peak was significantly correlated with leg press, leg
curl, leg extension 1-RMs, and total strength, with correlation coefficients
ranging from 0.40 to 0.54 (P.05).
|
|
|
|
Table 3. Correlations Between Absolute O2peak, Treadmill
Time, and Select Strength Measures*
|
|
|
Correlation coefficients between treadmill time to exhaustion and muscular
strength are shown in Table 3.
Treadmill time to exhaustion was significantly correlated with 1-RM leg extension
and total strength (P.05). However, treadmill
time was not significantly correlated with leg press or leg curl 1-RM (P .05).
COMMENT
This was the first study designed to assess the beneficial effects of
both low- and high-intensity traditional resistance exercise training regimens
on O2peak in elderly subjects. The principal findings
of this study were that O2peak increased 23.5% and 20.1%
and treadmill time to exhaustion increased 26.4% and 23.3% for the LEX and
HEX groups, respectively. These data suggest that resistance exercise of either
or both low or high intensity may be a valid means of increasing cardiorespiratory
endurance in older adults.
CARDIORESPIRATORY ENDURANCE
Previous investigations8, 10
examining the effects of resistance exercise on aerobic endurance have produced
mixed results. One factor that influences the disparate results is the style
of resistance exercise used by each study. For example, traditional circuit
weight training, characterized by high repetitions and short rest periods,
modestly increases O2peak (3%-11%).8, 18, 21
Conversely, more traditional programs consisting of multiple sets and longer
rest periods (2-4 minutes) have reported no change or sometimes a decrease
in O2peak.12, 22-23
However, Gettman et al,24 Hagberg et al,25 and Marcinik et al26
all reported nonsignificant changes in O2peak following
12 to 26 weeks of circuit weight training when the values were normalized
to body weight. Another confounding factor is the training program duration.
Training program durations have varied from 8 to 20 weeks, making comparisons
among studies difficult. For the remainder of this discussion, only studies
that used regimens similar in design and length to the present investigation
will be presented.
In the present study, a 23.5% and 20.1% increase in O2peak was observed for the LEX and HEX groups, respectively. These values
are considerably higher than the 5% to 12% increases reported by Frontera
et al18 and Gettman et al.21
Both Frontera et al and Gettman et al trained their subjects for only 12 weeks
compared with 24 weeks in this study. Furthermore, the average age for the
subjects in the study by Gettman et al was 35.7 years, considerably younger
than the subjects in the present study. Younger subjects may experience less
adaptation compared with older subjects. This fact may explain why the subjects
in the present study demonstrated a greater increase than is commonly reported.
The exercise regimen in the study by Gettman et al only consisted of leg flexion
and extension, whereas the present study used a comprehensive training regimen
with exercises for all major muscle groups. Wilmore et al14
reported an 11% increase in O2peak for their female subjects,
but no change for their male subjects. The authors speculated that the increase
in the female subjects occurred because they were less fit than their male
counterparts. It is known that less fit subjects commonly demonstrate greater
increases in strength or fitness when compared with fit subjects.8
The mechanism underlying the increase in O2peak
following resistance exercise training is unclear. It is possible that the
measurement of true O2peak in untrained subjects, particularly
elderly subjects, is prohibited or prevented by inadequate leg strength. Because
devices used to measure O2peak place an enormous premium
on leg strength, the subjects may be unable to reach their true maximum because
of a lack of strength in the lower extremities, not because they have central
cardiovascular limitations or exhaustion. Therefore, training-induced increases
in O2peak may not necessarily be due to an increased
ability to consume oxygen, but rather it may be that the person now has the
leg strength to approach or to reach central cardiovascular limitations. In
support of this postulate, O2peak was significantly correlated
to total strength, leg press, leg curl, and leg extension strength (P<.01). This finding is in accord with that reported
by Gettman and Ayers.27 That study examined
the effects of 2 different isokinetic resistance training regimens on aerobic
performance. Each of the 2 groups performed the same number of repetitions,
but one group performed more work than the other by moving at a slower speed
and against a greater resistance. The authors reported that the slow speed
group increased O2peak 7% more than the fast speed group,
suggesting a relationship between resistance training volume and aerobic capacity
improvement.
It is also possible that the increase in aerobic capacity in those people
who undergo resistance training may be in part due to an increase in oxidative
enzyme activities. Frontera et al18 reported
a 38% increase in citrate synthase enzyme activity following 12 weeks of resistance
exercise. They also reported a 15% increase in capillaries per fiber. The
regimen used in the study by Frontera et al consisted of 3 sets of 8 repetitions
at 80% of 1-RM for the knee flexors and extensors. The authors reported that
the increases in citrate synthase and capillary density were most likely due
to the resistance exercise and not an increase in daily activity due to their
increased strength, because their daily activity logs showed no change from
pretraining to posttraining. It is reasonable to conclude that a similar enzymatic
or metabolic adaptation may have occurred for our population, particularly
considering that the duration and volume of training was double that for the
study by Frontera et al.18
TREADMILL TIME TO EXHAUSTION
Treadmill time to exhaustion during the GXT was improved by 26.4% and
23.3% in the LEX and HEX groups, respectively. Since this increase was observed
during a maximal exercise bout, it is reasonable to conclude that endurance
performance during submaximal activities or activities of daily living would
also be improved. This could indicate that the trained elderly subjects from
this study may be better able to perform activities that require muscular
endurance, such as recreational exercise, shopping in a mall, or mowing the
lawn, compared with their untrained counterparts.
Several investigators12, 26, 28
have reported an increase in endurance performance without a concomitant increase
in O2peak. Marcinik et al26
reported a 33% increase in cycle time to exhaustion at 75% of O2max following 12 weeks of resistance training in young adults. The
subjects performed a circuit weight training regimen consisting of 3 sets
of 10 exercises separated by 30-second rest periods. The authors also reported
a 12% increase in lactate threshold. The increased time to exhaustion was
significantly (P<.001) correlated to increased
lactate threshold (r = 0.78) and 1-RM leg extension
strength (r = 0.89). Ades et al28
reported a 38% increase in submaximal treadmill walking time following 12
weeks of resistance exercise in older adults. Hickson et al12
reported increases in stationary cycle (47%) and treadmill running (12%) time
to exhaustion following 10 weeks of resistance training. The authors also
reported that O2peak only increased 4% as a consequence
of the exercise training. These data suggest that examining improved cardiorespiratory
endurance through measuring O2peak alone may be too limiting.
Functional assessment of improved muscular endurance may be more relevant
in terms of activities of daily living as opposed to strict changes in O2peak alone.
In the present investigation, resting heart rate was not reduced following
6 months of resistance training. However, the HEX group did have a significantly
higher peak heart rate compared with controls. The HEX group significantly
improved treadmill time, which may have allowed the trained subjects to achieve
a proportionately higher exercise intensity and heart rate. Therefore, the
most probable cause of a training-induced elevation in exercise heart rate
for the HEX group is the improved ability to sustain exercise, increase muscle
recruitment, and increase workload during the GXT.
PRACTICAL APPLICATION
Increased levels of cardiorespiratory endurance have been associated
with decreased rates of disease and mortality.1, 6
Traditionally, aerobic exercise has been viewed as the primary means of increasing
cardiorespiratory endurance. However, the data from the present study suggest
that resistance exercise may be a viable means of improving cardiorespiratory
endurance. This may be due to increased oxidative enzyme activities or by
increasing leg strength so that muscle weakness does not preclude achievement
of O2peak. Increased leg strength may allow aerobic exercise
training bouts to be performed at a greater intensity or for a longer duration,
also leading to improvements in aerobic capacity. Similar findings have not
been demonstrated in younger adults, indicating that the aerobic adaptations
to resistance exercise may be influenced by age and conditioning. Therefore,
it seems likely that improvements in aerobic capacity and endurance would
be greater in people who are more deconditioned, such as frail elderly people
or patients rehabilitating from an illness.
In summary, these are the first data that demonstrate improved aerobic
power in healthy elderly subjects following both low- and high-intensity resistance
exercise training regimens. Our data suggest that, in older adults, O2peak and endurance during a treadmill test are associated with and
possibly limited by muscular strength. These data indicate that resistance
exercise should be incorporated into a comprehensive exercise regimen to increase
muscular strength, cardiorespiratory endurance, and physical function.
AUTHOR INFORMATION
Accepted for publication July 31, 2001.
Corresponding author and reprints: Kevin R. Vincent, PhD, College
of Medicine, University of Florida Health Sciences Center, PO Box 101012,
Gainesville, FL 32610 (e-mail: kvincent{at}ufl.edu).
From the College of Medicine (Drs Vincent, Braith, and Lowenthal) and
Center for Exercise Science, College of Health and Human Performance (Dr Braith
and Mr Feldman), University of Florida, and Geriatric Research, Education
and Clinical Center, Veteran's Administration Hospital (Drs Kallas and Lowenthal),
Gainesville, Fla.
REFERENCES
| |
1. US Department of Health and Human Services. Physical Activity and Health: A Report of the Surgeon
General. Atlanta, Ga: US Dept of Health and Human Services, Centers for Disease
Control and Prevention, National Center for Chronic Disease Prevention and
Health Promotion; 1996.
2. Blair SN, Kohl III HW, Barlow CE, Paffenbarger RS Jr, Gibbons LW, Macera CA. Changes in physical fitness and all-cause mortality: a prospective
study of healthy and unhealthy men. JAMA. 1995;273:1093-1098.
ABSTRACT
3. Slattery ML, Jacobs DR, Nichman MZ. Physical fitness and cardiovascular disease mortality: the U.S. railroad
study. Am J Epidemiol. 1988;127:571-580.
FREE FULL TEXT
4. Menotti A, Keys A, Blackburn H, et al. Twenty-year stroke mortality and prediction in twelve cohorts of the
Seven Countries Study. Int J Epidemiol. 1990;19:309-315.
FREE FULL TEXT
5. Paffenbarger RS, Jung DL, Leung RW, Hyde RT. Physical activity and hypertension: an epidemiological review. Ann Med. 1991;23:319-327.
ISI
| PUBMED
6. Mancini DM, Eisen H, Kussmaul W, Mull R, Edmunds LH, Wilson JR. Value of peak exercise oxygen consumption for optimal timing of cardiac
transplantation in ambulatory patients with heart failure. Circulation. 1991;83:778-786.
FREE FULL TEXT
7. American College of Sports Medicine. The recommended quantity and quality of exercise for developing and
maintaining cardiorespiratory and muscular fitness in healthy adults. Med Sci Sports Exerc. 1998;30:975-991.
ISI
| PUBMED
8. Gettman LR, Pollock ML. Circuit weight training: a critical review of its physiological benefits. Phys Sports Med. 1981;9:44-60.
9. Pollock ML, Wilmore JH. Exercise in Health and Disease: Evaluation and Prescription
for Prevention and Rehabilitation. 2nd ed. Philadelphia, Pa: WB Saunders; 1990.
10. Stone MH, Fleck SJ, Triplett NT, Kraemer WJ. Health- and performance-related potential of resistance training. Sports Med. 1991;11:210-231.
ISI
| PUBMED
11. Fahey TD, Brown CH. The effects of an anabolic steroid on the strength, body composition,
and endurance of college males when accompanied by a weight training program. Med Sci Sports. 1973;5:272-276.
ISI
| PUBMED
12. Hickson RC, Rosenkoetter MA, Brown MM. Strength training effects on aerobic power and short-term endurance. Med Sci Sports Exerc. 1980;12:336-339.
ISI
| PUBMED
13. Hempel LS, Wells CL. Cardiorespiratory cost of the Nautilus express circuit. Phys Sportsmed. 1985;13:82-97.
14. Wilmore JH, Parr RB, Girandola RN. Physiological alterations consequent to circuit weight training. Med Sci Sports. 1978;10:79-84.
ISI
| PUBMED
15. Braith RW, Vincent KR. Resistance exercise in the elderly person with cardiovascular disease. Am J Geriatr Cardiol. 1999;8:63-79.
PUBMED
16. Flegg JL, Lakatta EG. Role of muscle loss in the age-related associated reduction in O2max. J Appl Physiol. 1988;65:1147-1151.
FREE FULL TEXT
17. Noakes TD. Implications of exercise testing for prediction of athletic performance:
a contemporary perspective. Med Sci Sports Exerc. 1988;20:319-330.
FULL TEXT
|
ISI
| PUBMED
18. Frontera WR, Meredith CN, O'Reilly KP, Evans WJ. Strength training and determinants of O2max in older
men. J Appl Physiol. 1990;68:329-333.
FREE FULL TEXT
19. Vincent KR, Braith RW, Feldman RA, et al. Resistance exercise and physical performance in elderly men and women. J Am Geriatr Soc. In press.
20. American College of Sports Medicine. Guidelines for Exercise Testing and Prescription. 6th ed. Philadelphia, Pa: Williams & Wilkins; 2000.
21. Gettman LR, Ward P, Hagan RD. A comparison of combined running and weight training with circuit weight
training. Med Sci Sports Exerc. 1982;14:229-234.
ISI
| PUBMED
22. Goldberg L, Elliot DL, Kuehl KS. A comparison of the cardiovascular effects of running and weight training. J Strength Cond Res. 1994;8:219-224.
23. Nakao M, Inoue Y, Murakami H. Longitudinal study of the effect of high intensity weight training
on aerobic capacity. Eur J Appl Physiol Occup Physiol. 1995;70:20-25.
FULL TEXT
|
ISI
| PUBMED
24. Gettman LR, Ayers JJ, Pollock ML, Jackson A. The effect of circuit weight training on strength, cardiorespiratory
function, and body composition of adult men. Med Sci Sports. 1978;10:171-176.
ISI
| PUBMED
25. Hagberg JM, Graves JE, Limacher M, et al. Cardiovascular responses of 70- to 79-yr-old men and women to exercise
training. J Appl Physiol. 1989;66:2589-2594.
FREE FULL TEXT
26. Marcinik EJ, Potts J, Schalbach G, Will S, Dawson P, Hurley BF. Effects of strength training on lactate threshold and endurance performance. Med Sci Sports Exerc. 1991;23:739-743.
ISI
| PUBMED
27. Gettman LR, Ayers JJ. Aerobic changes through 10 weeks of slow and fast speed isokinetic
training [abstract]. Med Sci Sports Exerc. 1978;10:47.
28. Ades PA, Ballor DL, Ashikaga T. Weight training improves walking endurance in healthy elderly persons. Ann Intern Med. 1996;124:568-572.
FREE FULL TEXT
RELATED LETTER
Sex Matters
Sharonne N. Hayes
Arch Intern Med. 2002;162(21):2490.
EXTRACT
| FULL TEXT
RELATED ARTICLE
Archives of Internal Medicine Reader's Choice: Continuing Medical Education
Arch Intern Med. 2002;162(6):722-723.
FULL TEXT
THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES
|
Resistance Exercise in Individuals With and Without Cardiovascular Disease: 2007 Update: A Scientific Statement From the American Heart Association Council on Clinical Cardiology and Council on Nutrition, Physical Activity, and Metabolism
Williams et al.
Circulation 2007;116:572-584.
ABSTRACT
| FULL TEXT
Prescribing Physical Activity for Cardiovascular and Metabolic Health
Zoeller
AMERICAN JOURNAL OF LIFESTYLE MEDICINE 2007;1:99-102.
ABSTRACT
Worksite intervention effects on physical health: a randomized controlled trial
Atlantis et al.
HEALTH PROMOT INT 2006;21:191-200.
ABSTRACT
| FULL TEXT
Aerobic Capacity in Patients Entering Cardiac Rehabilitation
Ades et al.
Circulation 2006;113:2706-2712.
ABSTRACT
| FULL TEXT
Resistance Exercise Training: Its Role in the Prevention of Cardiovascular Disease
Braith and Stewart
Circulation 2006;113:2642-2650.
FULL TEXT
Effect of Exercise Training on Peak Aerobic Power, Left Ventricular Morphology, and Muscle Strength in Healthy Older Women
Haykowsky et al.
J. Gerontol. A Biol. Sci. Med. Sci. 2005;60:307-311.
ABSTRACT
| FULL TEXT
Commentary
Lowenthal
J. Gerontol. A Biol. Sci. Med. Sci. 2003;58:M664-665.
FULL TEXT
Sex Matters
Hayes
Arch Intern Med 2002;162:2490-2490.
FULL TEXT
|
