Journal of Gerontology: MEDICAL SCIENCES
2002, Vol. 57A, No. 3, M168–M172
Copyright 2002 by The Gerontological Society of America
Anaerobic Power and Physical Function in
Strength-Trained and Non–Strength-Trained
Older Adults
Jill M. Slade,1 Tanya A. Miszko,1 Jennifer H. Laity,1 Subodoh K. Agrawal,2 and M. Elaine Cress1
1Department
of Exercise Science, University of Georgia, Athens.
2Athens Heart Center, Athens.
Background. Challenging daily tasks, such as transferring heavy items or rising from the floor, may be dependent on
the ability to generate short bursts of energy anaerobically. The purposes of this study were to determine if strengthtrained (ST) older adults have higher anaerobic power output compared with non–strength-trained (NST) older adults
and to determine the relationship between anaerobic power and performance-based physical function.
Methods. Thirty-five men and women (age 71.5 6.4 years, mean SD; NST: n 18, ST: n 17) were grouped
by training status. Outcome variables included relative anaerobic power (Wingate test), physical function measured with
the Continuous Scale Physical Functional Performance Test (CS-PFP, scaled 0 to 100), and anthropometric lean thigh
volume (LTV). Analysis of covariance (with age and sex as covariates) was used to determine group differences in the
dependent variables listed above. Pearson’s r was used to determine the relationship between anaerobic power, CS-PFP
total score (TOT), and CS-PFP lower body strength domain score (LBS).
Results. The ST group had significantly higher mean anaerobic power (NST 58.9 16 W/l, ST 96.3 23 W/l), CSPFP total (NST 61.2 13, ST 73.7 8), and LBS (NST 54.1 17, ST 70.9 8) compared with the NST group (p .05). However, LTV was similar for both groups (NST 3.323 0.75; ST 3.179 0.79), which suggests that the ST
group had higher muscle quality compared with the NST group. Anaerobic power was significantly related to TOT (r .611, p .001) and LBS (r .650, p .001).
Conclusions. High levels of physical function in ST older adults may in part be explained by higher levels of anaerobic power associated with strength training.
S
USTAINING a physical capacity adequate to maintain
independence and carry out daily activities is a challenge encountered by many older adults. Age-associated declines in muscle mass (1,2), strength, and aerobic capacity
(3,4) contribute to the loss of physical function. Aerobic capacity is an important determinant of function (5,6). Oxygen
costs for daily activities have been measured at 0.70 l/min,
0.81 l/min, 0.90 l/min, and 1.4 l/min for slow walking (2
mph), showering, using a bedpan, and walking upstairs, respectively (7). In addition, a peak aerobic capacity of less
than 18 ml·kg1·min1 has been associated with low levels
of self-reported physical function in daily tasks (5). Due to
age-related declines in aerobic capacity, older adults may
need to rely on anaerobic pathways to complete daily tasks.
Although data support an age-related decline in anaerobic
capacity (7.5% decline per decade) (8–11), energy supplied from anaerobic sources may be important to complete
challenging daily tasks. Older adults with diminished aerobic capacities may utilize a high percentage of their aerobic
capacity while completing daily tasks, may require more
frequent rest breaks, and may be more prone to fatigue.
These adults may independently complete serial tasks (combining two or more daily tasks) in spite of low aerobic capacities, but only by taking frequent rest breaks. In addition,
more demanding daily tasks, such as getting up from the
floor or transferring heavy items, may require quick moveM168
ment and power, which may require use of an anaerobic
pathway. Daily task completion includes short tasks that require less than 30 seconds to complete and long tasks that
require more than 30 seconds to complete; both may be
challenging for an older adult. The completion of challenging daily tasks as well as serial tasks may be affected by
anaerobic abilities.
If anaerobic power is important to the completion of daily
tasks, then exercise protocols that increase anaerobic power
should be implemented. Strength training is primarily an
anaerobic activity and may affect anaerobic power because
exercise sets are brief and typically of moderate to high intensity, reflecting the use of ATP-PCr and glycolytic pathways. In contrast, aerobic exercise trains oxidative pathways and enhances the ability to perform sustained work
but may not enhance the ability to complete short, highintensity tasks. Highly strength-trained individuals demonstrate high anaerobic power (11,12), and improvements in
anaerobic power have been reported following strength
training in younger individuals (13–17). Strength training in
older adults may indicate a similar response. The purpose of
this article is three-fold: (i) to examine anaerobic power in
strength-trained (ST) and non–strength-trained (NST) older
adults, (ii) to evaluate physical function in these two groups,
and (iii) to determine the relative contribution of anaerobic
power to physical function. We hypothesized that ST older
ANAEROBIC POWER AND PHYSICAL FUNCTION
adults would have higher mean and peak anaerobic power
and physical function compared with NST older adults. We
further hypothesized that anaerobic power would be positively correlated with physical function.
METHODS
Participants
We recruited healthy older adults (aged 60–85) from the
Athens, GA community who met the criteria for the ST and
NST groups. We attempted to recruit equal numbers of men
and women for each group (ST: 10 men, 7 women; NST: 8
men, 10 women). Current participation in a strength-training program ( 2 d/wk for 12 or more weeks) consisting of
whole-body strength training ( 8 exercises including leg
extension, leg press, or squat exercise) was used to determine eligibility for the ST group. Aerobic training was not
an exclusionary criterion. Exclusion criteria for both groups
included uncontrolled diabetes, diseases with variable disorders (neuromuscular conditions such as multiple sclerosis
and Parkinson’s disease), recent bone fracture, knee or hip
replacement (within 12 months), severe osteopenia, and severe hypertension (resting blood pressure 160/90). Following a physician’s clearance, the subjects gave written informed consent prior to participation in the research study
as approved by the Institutional Review Board at the University of Georgia.
Physical Performance Measures
Anaerobic power (mean and peak power) was measured
during a cardiologist-supervised Wingate test. The 30-second Wingate test was performed on a friction-braked bike
(model 814E; Monark, Varberg, Sweden). An optical sensor
was used to detect reflective markers on the flywheel of the
cycle ergometer. The sensor was interfaced with a PC
equipped with software from Sports Medicine Industries
(St. Cloud, MN) to calculate power indices. Measures obtained included peak power (highest 5-second average) and
mean power (average power output over 30 seconds). Results are expressed absolute (W) and relative to lean thigh
volume (LTV) in liters (W/l). Fat-free mass (FFM) was
used to determine a proportional load applied during the
Wingate test.
Load (kp) (57.4 FFM)/0.085
This equation is based on a 70-kg person with 18% body
fat (FFM 57.4 kg) and a load of 0.085 kp/kg body weight.
Before, during, and after the test, 12-lead electrocardiograph and blood pressure were recorded. Each subject performed a 5-minute warm-up at a low resistance, interspersed with 5-second sprints at various resistance settings.
The rating of perceived exertion (RPE) was assessed immediately after the test using the Borg scale (18), and heart rate
was recorded. A whole-blood sample was obtained 7.5 minutes postexercise from a prewarmed finger. Heparinized
samples were processed in duplicate immediately using a
lactate analyzer (YSI 2300; Stat Plus, Yellow Springs, OH).
Leg strength was determined from a one-repetition maximum (1-RM) using a double leg press (Alliance Rehab,
Chattanooga, TN). 1-RM is defined as the maximal weight
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that can be lifted through the full range of motion one time
while holding to good form. Participants were familiarized
with the leg press prior to the 1-RM test with two sets of 5
to 10 repetitions at a moderate resistance (40 to 80 lbs), adjusting the starting position to achieve 90 hip and knee
flexion. On a separate day, each subject returned to the lab
for the 1-RM test. After one set of 5 to 10 repetitions at a
moderate resistance, 1-RM testing commenced, and weight
was gradually added until the participant could not press the
machine one time. Rest intervals between each 1-RM attempt trial were 3 minutes. Maximal strength was measured to the nearest 5-lb increment.
The Continuous Scale Physical Functional Performance
Test (CS-PFP) was used to evaluate physical function. In
brief, the CS-PFP is a valid and reliable measure of physical
function without known ceiling effects, and therefore the
CS-PFP is ideal for quantifying function in adults with
higher levels of fitness (19). The CS-PFP is comprised of 16
everyday tasks including making a bed, getting down and
up from the floor, stair climbing, and transferring laundry
according to standardized instruction. A detailed description
of the set-up and test administration has been published
elsewhere (19,20) and is described on the World Wide Web
(http://www.coe.uga.edu/csp-pfp/). Each task contributes to
the total CS-PFP score and one or more of the five domains
that comprise a total CS-PFP score (TOT), scaled 0 to 100.
The domains of the CS-PFP are lower body strength (LBS),
upper body strength (UBS), upper body flexibility, balance
and coordination, and endurance. CS-PFP interrater reliability for this lab is high (r .988, p .010).
Body Composition
Percent fat was estimated from the sum of seven skinfold
sites using calipers (Lange, Cambridge, MD) and valid sexspecific equations (21,22). LTV was determined using anthropometric procedures as previously described (23). The
same tester measured each site twice, and values were recorded within 2 mm and 0.25 cm for skinfolds and circumferences, respectively.
Statistical Analysis
Statistical analyses were performed using SPSS for Windows, version 10 (SPSS Inc., Chicago, IL). A one-way
ANCOVA was used to examine differences in anaerobic
power output and physical function between training groups.
Age and sex were used as covariates. The data were analyzed
for linear, cubic, or quadratic trends to examine the relationship
between anaerobic power and physical function. Linear trends
were further analyzed using Pearson’s correlation (r). An alpha
level of .05 was used to determine statistical significance.
RESULTS
Selected physical characteristics are listed in Table 1. The
ST groups were significantly stronger than the NST group
(p .040; CI: NST 84.4–116.6, ST 110.2–141.4), but there
were no significant differences in LTV between the groups.
The groups averaged a similar number of medications per
subject (NST: 1.8 medications; NST: 1.7 medications).
Groups also had similar amounts of moderate aerobic activity (NST: 3.0 days per week; ST: 2.8 days per week), which
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SLADE ET AL.
Table 1. Physical Characteristics and Anaerobic Power
Measure
Age, yr
Height, cm
Weight, kg
FFM, kg
Lean thigh volume, 1
Leg strength (1-RM), kg
Mean power, W
Peak power, W
Lactate, mmol/1
Male NST
(n 7)
Female NST
(n 10)
NST Group
(n 17)
Male ST
(n 10)
Female ST
(n 8)
ST Group
(n 18)
76 7
177.11 9.6†
82.00 7.8†
61.65 6.8†
4.024 0.45†
129.22 28.2†
249.90 49.8
357.00 55.5†
5.39 1.3†
73 7
161.09 6.2
63.89 7.7
42.5 3.29
2.792 0.41
64.32 15.5
164.80 62.4
244.60 96.7
4.01 1.6
74 7
167.69 11.0
71.35 13.1
50.39 10.8
3.323 0.75
91.04 39.0
199.80 70.6
282.09 99.5
4.56 1.6
71 5*
174.47 5.8†
81.82 7.7†
61.08 6.3†
3.711 0.59†
163.64 47.1
357.10 81.4†
467.73 91.3†
6.36 1.1†
66.3 3*
158.36 4.5
71.61 11.3
45.44 4.0
2.513 0.38
98.58 20.6*
231.25 31.4
297.13 47.6
5.03 0.9
69 5*
167.30 9.7
77.28 10.6
54.13 9.6
3.179 0.79
134.72 49.6*
301.22 90.1
391.92 114.0
5.77 1.2*
Notes: Values are means SD. NST nonstrength trained; ST strength trained; FFM fat-free mass.
*p .05 training group difference, †p .05 sex difference.
included bicycling, walking, swimming, and tennis for at
least 25 minutes. Subjects in the ST group had been training
for 3 months to 40 years (mean 4.89 years, median 5.5
months; mode 3 months) and strength trained an average of
2.8 days per week (range 2–4 days).
Performance values from the Wingate anaerobic test are
shown in Table 1. Anaerobic power expressed absolute and
relative to body weight was not significantly different between the training groups. However, anaerobic power expressed relative to LTV (W/l) was significantly different
between the groups for mean power ( p .010; CI: NST
58.8–78.5, ST 79.3–97.6) and peak power ( p .016; CI:
NST 78.5–107.0, ST 106.0–133.0) (Figure 1).
Following the Wingate test, RPE was equivalent for both
groups (ST: 19; NST: 18). Heart rate immediately following
the Wingate test averaged 151 and 139 beats per minute for
the ST and NST groups, respectively. Blood lactate values
are reported in Table 1. A strong positive relationship was
observed between absolute peak power and blood lactate
(r .857, p .01). The load applied during the Wingate
anaerobic test averaged 0.077 kp/kg body weight and 0.067
kp/kg for men and women, respectively, and did not differ
between the training groups.
Physical function was significantly greater in the ST
group as shown in Figure 2 (TOT p .022; CI: NST 58.8–
68.7, ST 67.6–77.4. LBS p .023; CI: NST 51.6–63.5, ST
62.1–74.0. UBS p .044; CI: NST 67.3–77.0, ST 74.9–
Figure 1. Anaerobic power relative to lean thigh volume (SEM)
for strength-trained (ST) and non–strength-trained (NST) groups.
*p .05.
84.6). The LBS domain score in the female ST group was
50% greater than in the NST women ( p .002; mean
scores: NST 48.2 15, ST 71.5 7).
A positive linear trend was significant between anaerobic
power and LBS (Figure 3) and between anaerobic power
and TOT (Table 2). Correlations between anaerobic power,
physical function, and age are displayed in Table 2. Mean
anaerobic power explained 44.9% of the variance in the
lower body strength domain of the CS-PFP.
DISCUSSION
This study demonstrates that ST adults have greater
anaerobic power output and physical function than NST
older adults. Although the ST and NST groups had similar
LTV, the ST group produced more power relative to their
estimated LTV. In addition, relative anaerobic power was
positively related to physical function.
Both ST and NST groups reported high levels of exertion
(RPE) and also achieved age-predicted maximal heart rate
(220 age 1 SD) during the Wingate anaerobic test, indicating an equivalent and near-maximal effort. Blood lactate was significantly related to anaerobic power. Due to the
positive relationship between lactate production and anaerobic glycolysis (24), we expected to find higher levels of lactate production with greater levels of anaerobic power.
Figure 2. Physical function scores from Continuous Scale Physical
Functional Performance test (CS-PFP) in strength-trained (ST) and
non–strength-trained (NST) groups (*p .05). Domains of CS-PFP:
UBS upper body strength; UBF upper body flexibility; LBS lower body strength; BALC balance and coordination; END endurance; TOT total CS-PFP score.
ANAEROBIC POWER AND PHYSICAL FUNCTION
M171
Table 2. Pearson Product Correlations Between Physical Function,
Anaerobic Power, and Age
CS-PFP-TOT CS-PFP-LBS
CS-PFP-TOT
CS-PFP-LBS
Peak power
Mean power
Age
1.000
.944**
1.000
Peak Power Mean Power
(W/l)
(W/l)
.550*
.627*
1.000
.611**
.670**
.940**
1.000
Age
.398*
.473**
.658**
.628*
1.000
Notes: CS-PFP-TOT total physical function score; CS-PFP-LBS lower
body strength domain of Continuous Scale Physical Function Performance test
(CS-PFP); mean and peak power anaerobic power relative to lean thigh volume (W/l) from the Wingate test.
*p .05; **p .01.
Figure 3. Relationship between lower body strength domain of
physical function measured by the Continuous Scale Physical Functional Performance test to relative peak power (, solid line) and
mean power (, dashed line), p .01.
Our finding of greater anaerobic power without concurrent reflection in muscle mass has been previously documented. Shaw and Snow (25) report increases in peak
anaerobic power (13.2% 12%) in older women that were
not explained by increases in muscle mass following a combined jumping and weight training (lunges, squats, step-ups,
and toe raises) program. Higher relative anaerobic power in
the ST group suggests that ST adults more fully activate
their muscle. Data from both rat (26) and human studies
(27–29) show increased specific tension (strength/unit area)
following strength training and increased muscle activity
through EMG (30), which may account for increased
strength associated with neural adaptations. Higher power
output through neural adaptation may be achieved through
increased recruitment of motor units, synchronization, increased synergistic activation of other musculature, or decreased activation of antagonistic muscle groups. The ST
group may also have higher anaerobic enzyme activities or
substrates, which have been reported to increase with
strength training (31). Muscle composition (percent fasttwitch fibers) may also contribute to higher anaerobic
power output (32,33). Although possible, it is unlikely that
higher relative anaerobic power output in the ST group resulted from a higher proportion of type II fibers compared
with the untrained group. Due to the design of this study, we
were unable to determine the mechanism responsible for the
higher power output for the ST group.
Our results confirm several previous studies that show
that functional performance is improved by strength training (20,34,35). However, to our knowledge, no one has
looked at those factors associated with strength training that
are important as contributors to functional performance.
Our data show that ST adults carried more weight (29%)
and moved faster (17%) than the NST group. Specifically,
when examining the female groups, the greater LBS scores
from the ST group suggest that physical functional performance may be greatly enhanced through strength training.
Results of this study indicate that anaerobic power production is related to the ability to complete daily activities.
Lower extremity power is highly related to stair climbing,
rising from the chair and floor, and walking speed (r .53–
.88) (36,37). Using the CS-PFP to evaluate physical function, we showed that whole-body function (total physical
function score) and multi-task lower body function (LBS
domain) were significantly related to anaerobic power production. The CS-PFP test may be an ideal measure of physical function for these purposes due to the serial nature of the
tasks, the quantification of domains, and the ability to assess
high-functioning individuals without a ceiling effect.
Anaerobic power output may be a critical component for
completing serial tasks, occasional highly demanding tasks,
and emergency tasks (e.g., correcting balance after a trip).
Daily tasks, such as transferring wet laundry, carrying groceries, and rising from the floor, can be highly demanding
for an older adult. Dutta and colleagues suggest that older
adults are challenged by “emergency tasks” in daily life
(38). These emergency tasks include correcting balance after a trip, stopping abruptly, transferring heavy items, and
rising from the floor. Success in these tasks may depend on
adequate anaerobic power. The CS-PFP measure of physical function includes highly demanding or emergency daily
tasks (floor sit to stand, a grocery task, a bus-stop task with
baggage, and a stair climb), which may be reflective of
anaerobic power.
This study shows positive support for strength training in
older adults. However, there were some limiting factors.
This cross-sectional study design does not provide direct
evidence for changes in anaerobic power. Strength training
regimens of the ST group differed in the training frequency,
intensity, and volume, as well as in the type of exercises
regularly completed and the number of months individuals
had been strength training.
In conclusion, older adults who strength trained a minimum of 2 d/wk achieved higher anaerobic power than NST
adults, independent of age. ST individuals produced more
power per unit of LTV and had higher physical function
than the NST group, indicating that strength training possibly affects muscle quality. High levels of physical function
in ST older adults may be explained by an increase in anaerobic power resulting from strength training.
Acknowledgments
This research was supported by the Georgia Gerontology Consortium
Seed Grant. We thank Dr. Harry Duval and Dr. Kirk Cureton for providing
essential laboratory space and equipment.
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SLADE ET AL.
Address correspondence to Jill Slade, Department of Exercise Science,
University of Georgia, Athens, GA 30602. E-mail: [email protected]
21.
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Received April 17, 2001
Accepted July 3, 2001
Decision Editor: John E. Morley, MB, BCh