Content uploaded by Shannon J. Fitzgerald
Author content
All content in this area was uploaded by Shannon J. Fitzgerald on Jun 24, 2015
Content may be subject to copyright.
Muscular Fitness and All-Cause
Mortality: Prospective Observations
Shannon J. FitzGerald, Carolyn E. Barlow, James B. Kampert,
James R. Morrow, Jr., Allen W. Jackson, and Steven N. Blair
Background: The beneficial effects of cardiorespiratory fitness on mortality
are well known; however, the relation of muscular fitness, specifically muscu-
lar strength and endurance, to mortality risk has not been thoroughly exam-
ined. The purpose of the current study is to determine if a dose-response relation
exists between muscular fitness and mortality after controlling for factors such
as age and cardiorespiratory fitness. Methods: The study included 9105 men
and women, 20–82 years of age, in the Aerobics Center Longitudinal Study
who have completed at least one medical examination at the Cooper Clinic in
Dallas, TX between 1981 and 1989. The exam included a muscular fitness
assessment, based on 1-min sit-up and 1-repetition maximal leg and bench
press scores, and a maximal treadmill test. We conducted mortality follow-up
through 1996 primarily using the National Death Index, with a total follow-up
of 106,046 person-years. All-cause mortality rates were examined across low,
moderate, and high muscular fitness strata. Results: Mortality was confirmed
in 194 of 9105 participants (2.1%). The age- and sex-adjusted mortality rate
of those in the lowest muscular fitness category was higher than that of those
in the moderate fitness category (26.8 vs. 15.3 per 10,000 person-years, re-
spectively). Those in the high fitness category had a mortality rate of 20.6 per
10,000 person-years. The moderate and high muscular fitness groups had
relative risks of 0.64 (95%CI = 0.44–0.93) and 0.80 (95%CI = 0.49–1.31),
adjusting for age, health status, body mass index, cigarette smoking, and cardio-
respiratory fitness when compared with the low muscular fitness group. Con-
clusions: Mortality rates were lower for individuals with moderate/high
muscular fitness compared to individuals with low muscular fitness. These
findings warrant further research to confirm the apparent threshold effect be-
tween low and moderate/high muscular fitness and all-cause mortality.
Key Words: strength, prevention, prospective study, Aerobics Center Longitu-
dinal Study
Journal of Physical Activity and Health, 2004, 1, 7-18
© 2004 Human Kinetics Publishers, Inc.
7
S.J. FitzGerald, C.E. Barlow, J.B. Kampert, and S.N. Blair are with the Centers for
Integrated Health Research at The Cooper Institute, Dallas, TX 75230. J.R. Morrow, Jr.,
A.W. Jackson, and FitzGerald are with the Department of Kinesiology, Health Promotion,
and Recreation at the University of North Texas, Denton, TX 76203.
ORIGINAL RESEARCH
8FitzGerald et al.
Health-related physical fitness is often described as comprising cardiorespiratory
or aerobic fitness, body composition, and muscular fitness. Measures of muscular
fitness include muscular strength and endurance. It is well established that cardio-
respiratory fitness and aerobic activity are protective against mortality;1,2 however,
the relation of muscular fitness, specifically muscular strength and endurance, to
mortality risk is unclear. A few investigators have examined the relationship be-
tween grip strength and all-cause mortality and generally have found statistically
significant inverse relationships after controlling for other risk factors.3,4,5,6 There
has been little research on the relation of muscular endurance to mortality, al-
though Katzmarzyk et al.7 recently suggested an inverse association between the
number of sit-ups in 1 min and mortality in the Canada Fitness Survey.
There may be many health benefits directly and indirectly associated with
muscular fitness, and these could lead to a relationship between muscular fitness
and mortality. Although the evidence is equivocal, literature reviews suggest that
those who perform better on strength tests tend to be healthier8,9 and have better
functional capacity10,11 than those who do not perform as well. High levels of
muscular strength may indirectly improve health profiles through beneficial effects
on body composition and aerobic performance.12 Muscular strength and endur-
ance training programs have minor effects on maximal aerobic power, but they
may lead to improvements in submaximal exercise performance,12 thus reducing
the risk for mortality indirectly by lowering the risk for functional decline and
disability.13,14
The aim of the current study was to determine the relation between muscular
fitness and mortality after controlling for factors such as age, health status, body
mass index, cigarette smoking, and cardiorespiratory fitness. Muscular fitness, rep-
resented by a muscular strength and endurance index, included measures of upper
and lower body strength and abdominal muscular endurance. We examined the
dose-response relation of low, moderate, and high levels of muscular fitness to all-
cause mortality. We hypothesized that those in the moderate and high muscular
fitness categories would have lower rates of mortality compared with those in the
lowest muscular fitness category.
Methods
Study Population and Design
Data for the current study are from the Aerobics Center Longitudinal Study (ACLS).
The aim of the ACLS is to examine prospectively the association of physical activity
and physical fitness to health in men and women. Individuals who have completed
at least one medical examination at the Cooper Clinic in Dallas, TX are partici-
pants in the ACLS. To be eligible for the current study, participants also had to
have completed a muscular fitness assessment, which was offered from 1981–
1989, as part of their medical examination. They also completed a maximal tread-
mill test that followed a modified Balke protocol15 and achieved at least 85% of
their age-predicted maximal heart rate on the test. Annually, the Institutional Review
Boards of The Cooper Institute and the University of North Texas reviewed and
approved the study protocol. Prior to the examination, the participants fasted for
12 hours, were asked not to smoke on the day of the examination, and granted
written informed consent for the examination and follow-up. The evaluation in-
cluded a physical exam, anthropometrics, blood chemistry tests, blood pressure, a
Muscular Fitness and Mortality 9
maximal treadmill exercise test to assess cardiorespiratory fitness, and a question-
naire of personal and family medical history, demographic characteristics, and health
habits.
Following the standard examination, participants could volunteer to com-
plete a muscular fitness assessment. No standardized contraindications precluded
an individual from participating. They were allowed to volunteer as long as their
examining physician did not feel that participating in the assessment would worsen
an existing medical condition or place them at risk.16
Clinical Examination
Various tests were conducted as part of the muscular fitness assessment. Compo-
nents of the assessment included in the current study were 1-repetition maximal
bench and leg press lifts and a 1-min bent leg sit-up test. Briefly, the sit-up test
consisted of the participants performing as many correct bent leg sit-ups as pos-
sible in 1 min with their hands behind their head and their feet flat on the floor,
held by a technician. The 1-repetition maximal bench and leg press tests were all
performed on Universal weight machines (Universal Equipment, Cedar Rapids,
IA). The initial weight for the bench press was 70% of the participant’s body weight.
Weight was added in 2.3- to 4.5-kg increments until maximal effort was performed,
usually in five trials or less. This was also done for the maximal leg press test;
however, the starting weight for the participant was 100% of their body weight.
These assessment protocols have previously been described more thoroughly.16,17
Maximal treadmill tests were conducted to assess cardiorespiratory fitness.
Maximal oxygen uptake (VO2max) is the best indicator of cardiorespiratory fitness.18
Since VO2max is highly correlated (r = 0.92 in men and r = 0.94 in women) with the
duration of our maximal treadmill exercise test,19,20 time from the treadmill test
was used to estimate cardiorespiratory fitness in the current study. The specific
treadmill protocol was as follows: The treadmill speed was originally set at
88m/min and remained that speed for the first 25 min of the test. Initially, the grade
was set at 0% for the first minute, then increased to 2% for the second minute, and
subsequently increased 1% each minute until 25 min into the test. At this point, the
grade stayed constant and the speed increased 5.4 m/min each minute until the test
was stopped. All participants were encouraged to provide a maximal effort perfor-
mance.
Cooper Clinic laboratory technicians analyzed blood chemistry levels using
automated techniques. The lab participates in and meets quality control standards
of the Centers for Disease Control and Prevention Lipid Standardization Program.
Blood pressure was ascertained by the auscultatory method utilizing standard pro-
cedures using a mercury sphygmomanometer with the patient in the sitting posi-
tion. A standard physician’s balance beam scale and stadiometer were used to
measure weight and height.21 From this measurement, we estimated obesity based
on body mass index (BMI) [weight (kg)/height (m2)].
Mortality Ascertainment
We conducted mortality follow-up through 1996 primarily using the National Death
Index. The National Death Index has a sensitivity of 96% and a specificity of
100% for determining deaths in the general population.22 Once we identified possible
decedents, departments of vital statistics in the appropriate states were contacted,
10 FitzGerald et al.
and official copies of death certificates were requested. We compared information
on the death certificates with clinical records to confirm that the death certificate
matched the individual. A nosologist coded the underlying and potentially 4 other
contributing causes of death according to the International Classification of Diseases
(9th ed., revised; ICD-9).
Statistical Analysis
We created muscular fitness categories from a muscular fitness scoring index that
was based on results from 1-repetition maximal bench and leg press tests and from
a 1-min sit-up test. Tertiles were calculated for each test separately for men and
women and were assigned a 0 to 2 score (0 = the lowest tertile, 2 = the highest
tertile). Specific cutpoints for men and women for each test according to the score
are shown in Table 1. The individual scores were then summed to form the muscu-
lar fitness index (0 to 6 score). We investigated the cumulative incidence of all-
cause mortality across these scores and determined that the highest incidence of
mortality was in those who scored a 0 (n = 54) on the muscular fitness index, and
the lowest incidence was in those who scored a 6 (n = 8, data not shown). Based on
these observations, to have comparable numbers of deaths in each group, we de-
fined muscular fitness categories as follows: low = 0 on the muscular fitness index,
moderate = 1 to 3, and high = 4 to 6. We compared descriptive characteristics of
men and women across muscular fitness categories. We also conducted Pearson
correlation analyses to examine the strength of the associations among ungrouped
components of the muscular fitness assessment.
We calculated age- and sex-adjusted all-cause mortality rates per 10,000
person-years of observation across low, moderate, and high muscular fitness cate-
gories. The direct method was used for adjustment with the entire sample as the
standard.
Table 1 Cutpoints for Muscular Fitness Index Tertiles in Women and Men,
Aerobics Center Longitudinal Study
Test/score Men (N = 7605) Women (N = 1500)
Bench Press, maximal kg lifted
0£61.2 £27.2
1 61.3–74.8 27.3–36.3
274.9+ 36.4+
Leg press, maximal kg lifted
0£120.2 £63.5
1 120.3–140.6 63.6–81.6
2140.7+ 81.7+
Sit-ups, number in 1 min
0 0–28 0–20
1 29–36 21–28
237+ 29+
Muscular Fitness and Mortality 11
We used Cox proportional hazards regression to calculate multivariable ad-
justed relative risks (RR)23 for all-cause mortality. The log cumulative hazard plots
against follow-up time were parallel across groups. These models included age,
sex, smoking status, health status, cardiorespiratory fitness level, BMI, resting sys-
tolic blood pressure, serum cholesterol, and year of examination. We considered
individuals apparently healthy if, at the time of their exam, they had normal resting
and exercise electrocardiograms and did not report a history of myocardial infarc-
tion, high blood pressure, stroke, diabetes, or cancer. The 95% confidence inter-
vals (CI) around all RRs were also calculated. We conducted all data analyses
using SAS 8.2 statistical software (SAS Institute, Inc., Cary, North Carolina).
Results
Complete data were available on 9105 men and women, 20–82 years of age. Char-
acteristics of the study population by muscular fitness category are shown in Table 2.
More than 80% of the participants were men. Age, total cholesterol, and triglycerides
were lower in men and women in the high muscular fitness category than those in
the low or moderate muscular fitness category. Those in the high muscular fitness
group were also less likely to be current smokers or unhealthy and had better physical
activity/cardiovascular fitness profiles compared to those in the low or moderate
categories. Average follow-up time for each group ranged from 11.6 to 11.7 person-
years for a total follow-up time of 106,046 person-years. Approximately 4% of the
total follow-up time was accounted for individuals 60 years old and older.
Correlations among the three components of the muscular fitness index—
sit-up, leg, and bench press scores—are shown in Table 3. Bench and leg press
scores were the most highly correlated, r = 0.69 in women and r = 0.62 for men,
p< .001 for both. In men and women, sit-up score and bench press score were
moderately correlated (r = 0.48 to 0.41, respectively, p < .001 for both), and sit-up
score and leg press score were weakly correlated (r = 0.22 to 0.32, respectively,
p< .001 for both).
Mortality was confirmed in 194 participants (2.1%). Characteristics of the
decedents are shown in Table 4. Over 90% of the decedents were men, and 49.5%
were less than 50 years old. All of the deaths occurred between 1 and 14 years of
follow-up; 43.8% occurred between 6 and 10 years. Cancer was the cause of most
deaths (45.9%), followed by cardiovascular disease (25.2%). There were 56 deaths
in the low, 84 in the moderate, and 54 in the high muscular fitness groups, respec-
tively. Age- and sex-adjusted all-cause mortality rates per 10,000 person-years by
muscular fitness category are shown in Figure 1. The rate of those in the lowest
muscular fitness category was higher than that of those in the moderate fitness
category (26.8 vs. 15.3 per 10,000 person-years, respectively). Those in the high
fitness category had a mortality rate of 20.6 per 10,000 person-years.
Proportional hazards analyses demonstrated that those in the moderate and
high muscular fitness groups had a RR of 0.56 (95%CI = 0.40–0.80) and 0.65
(95%CI = 0.42–0.99), respectively, compared with the low muscular fitness group,
after adjustment for age and sex (Table 5). Test for linear trend for the categorical
muscular fitness variable reached borderline significance (p = .06). Test for linear
contrast comparing the combined effects of the moderate and high muscular fit-
ness groups with the low fitness group on mortality risk was statistically signifi-
cant (p < .01).
12 FitzGerald et al.
Table 2 Descriptive Characteristics of Men and Women
According to Muscular Fitness Category
Low Moderate High
Variable (N = 1069) (N = 4280) (N = 3756) p value
Men (%) 87.3 84.6 81.2 <.001
Age (y) 50.3 ± 9.1 43.6 ± 8.8 37.4 ± 7.7 <.001
Total cholesterol (mg/dl)†219.5 ± 44.4 213.2 ± 66.1 202.3 ± 40.1 <.001
HDL (mg/dl)†48.9 ± 13.6 48.6 ± 17.6 48.0 ± 13.1 .36
Triglycerides (mg/dl)†105.5 (75, 152) 100 (70, 148) 90.5 (65, 136) <.001
Glucose (mg/dl)†101.3 ± 16.8 99.8 ± 14.0 97.9 ± 10.6 <.001
Resting systolic blood
pressure (mm Hg) 118.9 ± 15.1 116.6 ± 13.0 117.1 ± 12.4 .001
Resting diastolic blood
pressure (mm Hg) 79.8 ± 9.7 78.4 ± 9.3 77.9 ± 9.1 <.001
BMI (kg/m2) 24.3 ± 2.9 25.0 ± 3.5 25.9 ± 4.0 <.001
Unhealthy (%)‡26.3 18.4 12.4 <.001
Current smoker (%) 16.9 14.7 12.8 .001
Cardiorespiratory fitness
(maximal METs on
treadmill test) 16.1 ± 4.5 18.4 ± 4.9 20.6 ± 4.9 <.001
Unfit (%)§10.7 8.9 6.7 .05
Sedentary (%)$28.6 22.1 16.2 <.001
Note. Mean ± SD or median (25th, 75th percentile) unless indicated. †To convert cholesterol
and HDL values to mmol/L, multiply by 0.0259. To convert triglycerides to mmol/L,
multiply by 0.0113. To convert glucose to mmol/L, multiply by 0.0555. ‡Abnormal or
equivocal resting or exercise electrocardiograms or a history of myocardial infarction, high
blood pressure, stroke, diabetes, or cancer. §Those in the lowest 20% age- and sex-specific
cardiorespiratory fitness category. $No regular physical activity reported 3 months before the
examination.
Table 3 Correlations Among Muscular Fitness Measures for Men and Women
Men (N = 7605) Women (N = 1500)
Measures Leg press†Bench press‡Leg press Bench press
Sit-ups§0.22 0.48 0.32 0.41
Leg press 0.62 0.69
Note. All correlations p < .001. †Maximal 1-repetition leg press. ‡Maximal 1-repetition
bench press. §Number of sit-ups in 1 min.
Muscular Fitness and Mortality 13
Table 4 Characteristics of 194 Decedents
Variable %
Men 91.2
≥50 years old 50.5
Follow-up time
1–5 years 26.8
6–10 years 43.8
11–14 years 29.4
Cause of death
Infectious disease 2.6
Cancer 45.9
Nutrition or metabolic disease 2.1
Nervous system 3.6
Cardiovascular disease 25.2
Digestive disease 2.0
Genitourinary disease 0.5
Injury or poisoning 1.6
Other 16.0
Unknown 0.5
Figure 1 — Mortality rates per 10,000 person-years by muscular fitness category.
14 FitzGerald et al.
There were no appreciable differences in results when baseline smoking and
health status were added to the model (Table 5). The moderate and high muscular
fitness groups had an adjusted RR of 0.58 (95%CI = 0.41–0.82) and 0.69 (95%CI
= 0.45–1.06) when compared with the low muscular fitness group. Linear contrast
comparing the mortality risk between the moderate and high muscular fitness groups
and the low fitness group was statistically significant (p = .01). When cardio-
respiratory fitness level, BMI, cholesterol, resting systolic blood pressure, and
baseline examination visit year were added to the model, the strength of the relation-
ships was slightly diminished (Table 5). Linear contrast for this model comparing
mortality risks of the moderate and high muscular fitness groups with the low
fitness group was borderline significant (p = .09). These analyses were repeated,
excluding all individuals who died within 3 years of their clinic exam (n = 18). The
results were not substantially changed with these exclusions (data not shown).
Table 5 Relative Risks of All-Cause Mortality
Across Muscular Fitness Categories
Model/category RR 95% CI
Model 1†
Low muscular fitness 1.0
Moderate muscular fitness 0.56 (0.40–0.80)
High muscular fitness 0.65 (0.42–0.99)
Model 2‡
Low muscular fitness 1.0
Moderate muscular fitness 0.58 (0.41–0.82)
High muscular fitness 0.69 (0.45–1.06)
Model 3§
Low muscular fitness 1.0
Moderate muscular fitness 0.64 (0.44–0.93)
High muscular fitness 0.80 (0.49–1.31)
Note. Fifty-six deaths in the low, 84 in the moderate, and 54 in the high muscular fitness
groups. †Adjusted for age and sex; p for trend = .06. ‡Adjusted for age, sex, health status, and
current smoking status. §Adjusted for age, BMI, sex, cardiorespiratory fitness, health status,
total cholesterol, resting systolic blood pressure, smoking status, and baseline examination
year.
Discussion
Mortality was confirmed in 194 of 9105 men and women over 106,046 person-
years of follow-up. Mortality rates across low, moderate, and high muscular fit-
ness categories, based on 1-min sit-up and 1-repetition maximal leg and bench
press scores, suggest there is a threshold effect, rather than a dose-response rela-
tion, between low muscular fitness and moderate/high muscular fitness and all-
cause mortality. Better muscular fitness was associated with lower age- and
sex-adjusted all-cause mortality rates.
Muscular Fitness and Mortality 15
When examining the relation between muscular fitness and all-cause mor-
tality using multivariate modeling, the moderate and high muscular fitness groups
had, respectively, a 44% and 35% reduction in risk compared with the low muscu-
lar fitness group, after adjusting for age and sex. Further adjustment for health and
current smoking status had minimal effects on the strength of the relationship,
with the risk reduction being 42% and 31% for the moderate and high muscular
fitness groups, respectively. Additional adjustment for cardiorespiratory fitness,
body mass index, cholesterol, resting systolic blood pressure, and baseline exami-
nation year slightly diminished the level of risk.
Our results support previously published literature regarding the relation
between muscular strength, a component of muscular fitness, and all-cause mor-
tality. Prospective studies have reported that survivors had higher strength at baseline
compared to those who died.24,25 Additional studies reported that the mortality risks
in those with low grip strength ranged from 20% higher to over twice that of the
high strength group.3,4,6,26 Metter and colleagues reported that lower grip strength
at baseline as well as declining grip strength over time were related to increased
mortality.5 Rantanen et al.6 examined these relationships across BMI strata and
found that the increased mortality risk for those with low grip strength was seen in
those who were low weight (BMI < 20), normal weight, and overweight/obese
(BMI ≥ 25).
There have not been many studies examining the relationship between all-
cause mortality and muscular endurance, another component of muscular fitness.
Investigators from the Canadian Fitness Survey found that men and women in the
lowest quartile for sit-up score had a significantly higher risk for all-cause mortal-
ity compared with those in the highest quartile.7 Fujita et al., however, did not find
a relationship between sit-up score and mortality.4
Most of the above-mentioned studies were performed in elderly cohorts (e.g.,
≥ 70 years old) and did not include a measure of cardiorespiratory fitness.3,24–26
These studies typically investigated the relationship between one component of
muscular fitness, usually strength, and mortality.3–6,24–26 For the most part, these
studies focused on strength assessed in one muscle group (e.g., grip strength). A
thorough strength assessment should include testing several major muscle groups,
including upper body, trunk, and lower body.2 Our study group was unique in that
the participants ranged in age from 20 to 82 years old and also had a measure of
cardiorespiratory fitness based on a maximal treadmill test. Since moderate and
high levels of muscular fitness could represent an active lifestyle, the ability to
adjust for cardiorespiratory fitness allowed us to focus specifically on the relation
of muscular fitness to mortality. In addition, our muscular fitness index was based
on both muscular strength and endurance tests, which involved the major muscle
groups of the upper and lower body and the trunk. The study results provide evi-
dence that participants with moderate/high muscular fitness had lower mortality
risk than low fit individuals.
Those who demonstrate high levels of strength tend to be healthier8,9 and
have better functional capacity10,11 than those with lower levels of strength. There-
fore, our results could be explained, in part, by the relationships between various
components of health and muscular strength. For example, it has been suggested
that low levels of muscular strength and/or endurance17,27 were predictive of poor
physical function, which in turn has been found to be related to an increased mor-
tality risk.13,14 Resistance training programs designed to improve muscular fitness
have been found to improve functional mobility in the elderly;28,29 therefore,
16 FitzGerald et al.
moderate and high levels of muscular fitness may reduce mortality risk through
improvements in health indices such as functional capacity. Additional beneficial
effects of resistance training programs include positive changes in bone mineral
density, body composition, and glucose metabolism.12,30
Strengths of the current study include the availability of an objective multi-
component assessment of muscular fitness and cardiorespiratory fitness on a large
sample of men and women. In addition, the thorough medical examination partici-
pants received at baseline allows us to control for additional risk factors such as
health status, systolic blood pressure, and cholesterol in multivariate models.
Because of the demographic structure of the population, predominantly white
and middle to upper socioeconomic status, the results of this study may not be
applicable to those in the general population of the United States. Earlier we com-
pared values of blood pressure, cholesterol, weight, and cardiorespiratory fitness
from subjects in the ACLS to participants in two other large epidemiological studies
that were conducted in representative populations in North America.31 The values
for these variables did not vary substantially across studies for age- and sex-specific
groups. The homogeneity of our sample on education, occupation, and income
reduces the potential for confounding by these characteristics.
Other limitations include the inability to analyze data for men and women
separately. This limitation was due to the low all-cause mortality rate in women
resulting in a lack of statistical power. Analyses were stratified by sex, and the
same trends between muscular fitness category and all-cause mortality were found
in men and women separately (data not shown). These relationships did not reach
statistical significance in women (p > .05). It is also possible that those individuals
who performed more poorly on the muscular fitness test had health conditions not
detected at the examination, making them at higher risk for mortality. However, all
participants received a thorough medical examination at baseline and were healthy
enough to achieve at least 85% of their age-predicted maximal heart rate on a
treadmill test. To further address this issue, we controlled for existing health con-
ditions in multivariate analyses and repeated analyses, excluding those who died
within 3 years of their exam. These adjustments did not alter the results substan-
tially. Finally, we examined muscular fitness at one point in time. The muscular
assessment was only offered from 1981 and 1989, and less than 8% of the sample
had more than one visit (data not shown). Given the lack of data for repeat muscu-
lar fitness assessments, we were unable to examine changes or maintenance of
muscular fitness over time. If changes in muscular fitness did occur, the strengths
of the associations reported potentially would be affected.
To our knowledge this is the first study to report a threshold effect between
low and moderate/high muscular fitness, based on muscular fitness screening, and
lower all-cause mortality. Future studies should examine the relation between
muscular fitness and the development of diseases such as coronary heart disease
and type 2 diabetes, as well as the effects of long-term maintenance and improve-
ments of muscular fitness on morbidity and mortality. Reports from organizations
such as the Centers for Disease Control and Prevention and the American College
of Sports Medicine1 and the Surgeon General2 suggest that physical activity regi-
mens designed to improve health should include a resistance training component.
Potentially, resistance training programs designed to improve total muscular fit-
ness should be recommended not only to improve overall health and functional
status, but perhaps to reduce all-cause mortality as well.
Muscular Fitness and Mortality 17
References
1. Pate RR, Pratt M, Blair SN, et al. Physical activity and public health: a recommenda-
tion from the Centers for Disease Control and Prevention and the American College of
Sports Medicine. JAMA. 1995;273:402-407.
2. U.S. Department of Health and Human Services. Physical Activity and Health: A Re-
port of the Surgeon General. Atlanta, GA: U.S. Department of Health and Human
Services, Centers for Disease Control and Prevention, National Center for Chronic
Disease Prevention and Health Promotion; 1996.
3. Anstey KJ, Luszcz MA, Giles LC, Andrews GR. Demographic, health, cognitive, and
sensory variables as predictors of mortality in very old adults. Psychol Aging. 2001;16:3-
11.
4. Fujita Y, Nakamura Y, Hiraoka J, et al. Physical-strength tests and mortality among
visitors to health-promotion centers in Japan. J Clin Epidemiol. 1995;48:1349-1359.
5. Metter EJ, Talbot LA, Schrager M, Conwit R. Skeletal muscle strength as a predictor
of all-cause mortality in healthy men. J Gerontol A Biol Sci Med Sci. 2002;57:B359-
B365
6. Rantanen T, Harris T, Leveille SG, et al. Muscle strength and body mass index as long-
term predictors of mortality in initially healthy men. J Gerontol A Biol Sci Med Sci.
2000;55:M168-M173
7. Katzmarzyk PT, Craig CL. Musculoskeletal fitness and risk of mortality. Med Sci Sports
Exerc. 2002;34:740-744.
8. Bassey EJ, Harries UJ. Normal values for handgrip strength in 920 men and women
aged over 65 years, and longitudinal changes over 4 years in 620 survivors. Clin Sci
(Lond). 1993;84:331-337.
9. Payne N, Gledhill N, Katzmarzyk PT, Jamnik VK, Keir PJ. Canadian musculoskeletal
fitness norms. Can J Appl Physiol. 2000;25:430-442.
10. Kell RT, Bell G, Quinney A. Musculoskeletal fitness, health outcomes and quality of
life. Sports Med. 1902;31:863-873.
11. Warburton DE, Gledhill N, Quinney A. Musculoskeletal fitness and health. Can J Appl
Physiol. 2001;26:217-237.
12. Warburton DE, Glendhill N, Quinney A. The effects of changes in musculoskeletal
fitness on health. Can J Appl Physiol. 2001;26:161-216.
13. Guralnik JM, Simonsick EM, Ferrucci L, et al. A short physical performance battery
assessing lower extremity function: association with self-reported disability and pre-
diction of mortality and nursing home admission. J Gerontol. 1994;49:M85-M94
14. Hirvensalo M, Rantanen T, Heikkinen E. Mobility difficulties and physical activity as
predictors of mortality and loss of independence in the community-living older popu-
lation. J Am Geriatr Soc. 2000;48:493-498.
15. Balke B, Ware RW. An experimental study of physical fitness in Air Force personnel.
US Armed Forces Med J. 1959;10:675-688.
16. Gordon NF, Kohl HW, III, Pollock ML, et al. Cardiovascular safety of maximal strength
testing in healthy adults. Am J Cardiol. 1995;76:851-853.
17. Brill PA, Macera CA, Davis DR, Blair SN, Gordon N. Muscular strength and physical
function. Med Sci Sports Exerc. 2000;32:412-416.
18. Wilmore JH. Design issues and alternatives in assessing physical fitness among appar-
ently healthy adults in a health examination survey of the general population. In: Drury
TF, ed. Assessing Physical Fitness and Physical Activity in Population-based Surveys.
Washington, DC: U.S. Government Printing Office; 1989:107-153.
18 FitzGerald et al.
19. Pollock ML, Bohannon RL, Cooper KH, et al. A comparative analysis of four proto-
cols for maximal treadmill stress testing. Am Heart J. 1976;92:39-46.
20. Pollock ML, Foster C, Schmidt D, et al. Comparative analysis of physiologic responses
to three different maximal graded exercise test protocols in healthy women. Am Heart
J. 1982;103:363-373.
21. Blair SN, Kampert JB, Kohl HW, et al. Influences of cardiorespiratory fitness and
other precursors on cardiovascular disease and all-cause mortality in men and women.
JAMA. 1996;276:205-210.
22. Stampfer MJ, Willett WC, Speizer FE, et al. Test of the National Death Index. Am J
Epidemiol. 1984;119:837-839.
23. Cox DR. Regression models and life tables (with discussion). J Royal Stat Soc. 1972;
Series B 34:187-220.
24. Rantanen T, Era P, Heikkinen E. Physical activity and the changes in maximal iso-
metric strength in men and women from the age of 75 to 80 years. J Am Geriatr Soc.
1997;45:1439-1445.
25. Schroll M, Avlund K, Davidsen M. Predictors of five-year functional ability in a longi-
tudinal survey of men and women aged 75 to 80. The 1914-population in Glostrup,
Denmark. Aging (Milano). 1997;9:143-152.
26. Laukkanen P, Heikkinen E, Kauppinen M. Muscle strength and mobility as predictors
of survival in 75–84-year-old people. Age Ageing. 1995;24:468-473.
27. Rantanen T, Guralnik JM, Foley D, et al. Midlife hand grip strength as a predictor of
old age disability. JAMA. 1999;281:558-560.
28. Fiatarone MA, Marks EC, Ryan ND, et al. High-intensity strength training in nonage-
narians. Effects on skeletal muscle. JAMA. 1990;263:3029-3034.
29. Hurley BF, Roth SM. Strength training in the elderly: effects on risk factors for age-
related diseases. Sports Med. 2000;30:249-268.
30. Pollock ML, Vincent KR. Resistance training for health. The President’s Council on
Physical Fitness and Sports Research Digest. 1996;Series 2:1-9.
31. Blair SN, Kohl HW, III, Paffenbarger RS, Jr., et al. Physical fitness and all-cause mor-
tality: a prospective study of healthy men and women. JAMA. 1989;262:2395-2401.
Acknowledgments
This study was supported in part by U.S. Public Health Service research grants from
the National Institute on Aging (AG06945) and National Institute of Arthritis and Musculo-
skeletal and Skin Diseases (AR39715), Bethesda, MD. We thank the physicians and techni-
cians of the Cooper Clinic, Kia Vaandrager and her staff for collecting data for this study,
Kenneth H. Cooper, M.D., for initiating the Aerobics Center Longitudinal Study, the MIS
and data entry staff of The Cooper Institute, Melba S. Morrow, M.A. for editorial assis-
tance, Neil Gordon, M.D., Ph.D., Principal Investigator, and Patricia Brill, Project Coordi-
nator, of the AR39715 project, for their contributions to that part of the study.
