Aerobic exercise and neurocognitive performance: a meta-analytic review of randomized controlled trials.

TLDR: Aerobic exercise training is associated with modest improvements in attention and processing speed, executive function, and memory, although the effects of exercise on working memory are less consistent.

Abstract: Objectives—Although the effects of exercise on neurocognition have been the subject of several previous reviews and meta-analyses, they have been hampered by methodological shortcomings and are now outdated as a result of the recent publication of several large-scale randomized controlled trials (RCTs). Methods—We conducted a systematic literature review of RCTs examining the association between aerobic exercise training on neurocognitive performance conducted between January, 1966 and July, 2009. Suitable studies were selected for inclusion according to the following criteria: randomized treatment allocation, mean age ≥ 18 years of age, duration of treatment > 1 month, incorporated aerobic exercise components, exercise training was supervised, the presence of a nonaerobic-exercise control group, and sufficient information to derive effect size (ES) data. Results—Twenty-nine studies met inclusion criteria and were included in our analyses, representing data from 2,049 participants and 234 effect sizes. Individuals randomly assigned to receive aerobic exercise training demonstrated modest improvements in attention and processing speed (g = .158 [95% CI: .055 to .260], P = .003), executive function (g = .123 [95% CI: .021 to . 225], P = .018), and memory (g = .128 [95% CI: .015 - .241], P = .026). Conclusions—Aerobic exercise training is associated with modest improvements in attention and processing speed, executive function, and memory, although the effects of exercise on working memory are less consistent. Rigorous RCTs are needed with larger samples, appropriate controls, and longer follow-up periods.

Figures

TABLE 2. Effects of Aerobic Exercise Interventions Versus Controls on Neurocognitive Performance for Various Cognitive Indices

TABLE 3. Classification of Neurocognitive Tests by Domain

Figure 1. Effect of aerobic exercise on attention and processing speed (n 24). Individuals randomized to aerobic exercise treatment exhibited improved attention and processing speed relative to controls (g 0.158; 95% confidence interval [CI], 0.055–0.260; p .003). Each study is denoted with a circle, with larger sample sizes corresponding to larger marks.

TABLE 1. Randomized Controlled Trials Examining the Effect of Aerobic Exercise on Neurocognitive Function

Figure 3. Effect of aerobic exercise on working memory (n 12). Individuals randomized to aerobic exercise treatment did not exhibit significant improvements in working memory relative to controls (g 0.032; 95% confidence interval [CI], 0.103 to 0.166; p .642). Each study is denoted with a circle, with larger sample sizes corresponding to larger marks.

Figure 2. Effect of aerobic exercise on executive function (n 19). Individuals randomized to aerobic exercise treatment exhibited improved executive function (g 0.123; 95% confidence interval [CI], 0.021–0.225; p .018). Each study is denoted with a circle, with larger sample sizes corresponding to larger marks.

Full text

Aerobic Exercise and Neurocognitive Performance: A Meta-Analytic Review of
Randomized Controlled Trials
PATRICK J. SMITH, MA, JAMES A. BLUMENTHAL,PHD, BENSON M. HOFFMAN,PHD, HARRIS COOPER,PHD,
TIMOTHY A. STRAUMAN,PHD, KATHLEEN WELSH-BOHMER,PHD, JEFFREY N. BROWNDYKE,PHD,
AND ANDREW SHERWOOD,PHD
Objectives: To assess the effects of aerobic exercise training on neurocognitive performance. Although the effects of exercise on
neurocognition have been the subject of several previous reviews and meta-analyses, they have been hampered by methodological
shortcomings and are now outdated as a result of the recent publication of several large-scale, randomized, controlled trials (RCTs).
Methods: We conducted a systematic literature review of RCTs examining the association between aerobic exercise training on
neurocognitive performance between January 1966 and July 2009. Suitable studies were selected for inclusion according to the
following criteria: randomized treatment allocation; mean age ⱖ18 years of age; duration of treatment ⬎1 month; incorporated
aerobic exercise components; supervised exercise training; the presence of a nonaerobic-exercise control group; and sufficient
information to derive effect size data. Results: Twenty-nine studies met inclusion criteria and were included in our analyses,
representing data from 2049 participants and 234 effect sizes. Individuals randomly assigned to receive aerobic exercise training
demonstrated modest improvements in attention and processing speed (g ⫽ 0.158; 95% confidence interval [CI]; 0.055–0.260;
p ⫽ .003), executive function (g ⫽ 0.123; 95% CI, 0.021– 0.225; p ⫽ .018), and memory (g ⫽ 0.128; 95% CI, 0.015– 0.241;
p ⫽ .026). Conclusions: Aerobic exercise training is associated with modest improvements in attention and processing speed,
executive function, and memory, although the effects of exercise on working memory are less consistent. Rigorous RCTs are
needed with larger samples, appropriate controls, and longer follow-up periods. Key words: cognitive performance, aerobic
exercise, neuropsychological performance, executive function, randomized controlled trial, meta-analysis.
ITT ⫽ intention-to-treat; RCT ⫽ randomized controlled trial.
INTRODUCTION
S
trategies to enhance neurocognitive functioning have
important public health implications as subclinical neuro-
cognitive deficits are associated with increased risk of neuro-
cognitive impairment (1), dementia (2), and mortality (3–7),
independent of traditional risk factors. One such strategy that
has gained increased attention is the use of aerobic exercise to
improve neurocognitive functioning (8 –12). Although the
value of exercise has been critically examined in review
articles (13) and meta-analytic syntheses (8 –11), there has
been a lack of agreement as to the magnitude of improvement
in neurocognitive function associated with physical activity
interventions. The current lack of consensus is due to differ-
ences in the evaluation of study methodologies, studies in-
cluded in the analyses, data analytic approaches, and in the
classification of various neurocognitive measures.
Cross-sectional studies have shown that physically active
individuals tend to exhibit better neurocognitive function rel-
ative to inactive individuals (13–22). Prospective observa-
tional studies have reported similar findings, demonstrating
that individuals who maintain greater levels of physical activ-
ity show improvements in neurocognitive function relative to
their sedentary counterparts (1,23–28). However, randomized
trials have provided inconsistent results, with some reporting
cognitive gains (29,30) and others equivocal findings (31).
Meta-analytic reviews of randomized controlled trials (RCTs)
have also reported great variation in the magnitude of im-
provement in neurocognition associated with aerobic exercise
(10 –12), with some meta-analyses reporting moderate cogni-
tive gains (9,10) and others reporting more modest improve-
ments (8,11,32).
In several recent meta-analyses, including a Cochrane re-
view (11), it was concluded that current data are insufficient to
show that improvements in neurocognitive function associated
with physical activity are due to improved cardiovascular
fitness, and that larger studies are necessary (11,32). However,
since the publication of this review, there have been several
large-scale RCTs examining this relationship (30,31,33,34). In
addition, although one previous systematic review (12) exam-
ined the effects of various forms of physical activity on
boosting cognitive function (primarily general orientation)
among individuals with dementia, no reviews have combined
data from trials attempting to prevent dementia among vul-
nerable populations (i.e., individuals with cognitive impair-
ment). The Cochrane review was limited, in this sense, as
persons with neurocognitive impairments (e.g., mild cognitive
impairment [MCI] and depression) were excluded (11). Fur-
thermore, previous meta-analyses examining this relationship
may have been influenced by the inclusion of two relatively
large studies reporting substantial treatment effects that were
not truly randomized (9,35,36), which may have overly influ-
enced the reported effects. Therefore, we conducted a meta-
analysis that included the most recent exercise intervention
trials and addressed several issues including: 1) the effects of
aerobic exercise training on specific domains of neurocogni-
tive performance, including attention and processing speed,
executive function, working memory, and memory; 2) the
influence of specific dimensions of the exercise prescription,
such as the mode, duration, and intensity of the exercise
From the Department of Psychiatry and Behavioral Sciences (P.J.S., J.A.B.,
B.M.H., K.W.-B., J.N.B., A.S.), Duke University Medical Center, Durham,
North Carolina; and the Department of Psychology and Neuroscience (H.C.,
T.A.S.), Duke University, Durham, North Corolina.
The research was supported, in part, by Grants MH 49679 and HL080664-
01A1 from the National Institutes of Health and Grant M01-RR-30 from the
General Clinical Research Center Program, National Center for Research
Resources, National Institutes of Health (J.A.B.).
Address correspondence and reprint requests to Patrick Smith, Box 3119,
Department of Psychiatry and Behavioral Sciences, Duke University Medical
Center, Durham, NC 27710. E-mail: Smith562@mc.duke.edu
Received for publication March 23, 2009; revision received December 3, 2009.
DOI: 10.1097/PSY.0b013e3181d14633
239Psychosomatic Medicine 72:239–252 (2010)
0033-3174/10/7203-0239
Copyright © 2010 by the American Psychosomatic Society

intervention; and 3) the issue of individual differences in
response to exercise training, with a focus on baseline, pre-
exercise level of cognitive functioning as a potential moder-
ator of exercise effects (i.e., we compared individuals with
MCI to cognitively intact samples), as well as the age of study
participants.
METHODS
To determine the effects of aerobic exercise interventions on neurocog-
nitive status, an extensive literature search was conducted, using the following
databases between January 1966 and July 2009: MEDLINE, Pubmed, EMBASE,
Gateway, CENTRAL, PsycINFO, Dissertation Abstracts International, Edu-
cational Research in Completion (ERIC), Sports Discus, Cochrane Register,
PEDRO, Ageline, and CINAHL. The following search terms were used:
cogniti*, cognitive performance, age*, elderly, mental performance, and
neuropsychological in combination with fitness, aerobic, cardiovascular, VO
2
,
and physical activity. Additional titles were identified by a manual search of
relevant journals and by identification of references included in previous
meta-analyses. Unpublished dissertations and conference papers were also
obtained, when possible.
Suitable studies were selected for inclusion according to the following crite-
ria: 1) randomized treatment allocation; 2) mean age ⱖ18 years of age and
nondemented; 3) duration of treatment ⬎1 month; 4) involved aerobic exercise
training (e.g., brisk walking, biking, or jogging). Age 18 years was selected as a
lower age limit to control for developmental age differences in cortical thickness
and myelination, which stabilize around the second decade of life (37). Studies
utilizing walking interventions that were not aerobic were not included (e.g., slow
walking with frequent breaks) to ensure that included trials incorporated some
aerobic exercise component. Additional inclusion criteria included 5) the pres-
ence of a control group that did not engage in aerobic exercise; and 6) sufficient
information to derive an estimate of effect size (ES).
After initial identification and retrieval of studies, several were found to
be quasirandomized studies (36) or used case-control methodologies
(15,36,38 – 44), were of insufficient duration to include (45–47), were found
not to be nonrandomized based on personal communication with the trial’s
principal investigator (36), or did not utilize a nonaerobic exercise control
group (48,49). Another trial was conducted among adolescents and was,
therefore, excluded (50). Several trials utilized “dual-task” interventions (e.g.,
walking and talking) (51–53) or balance and strength-training (54,55) and
were, therefore, not included as it could not be ascertained whether exercise
was of sufficient intensity to produce aerobic changes. Several trials were not
included because they utilized physical activity interventions with exclusively
nonaerobic exercise components among individuals with dementia (52,56–
65). The few studies utilizing walking interventions were either explicitly
nonaerobic (58) or allowed residents with limited mobility (e.g., using walk-
ers) to rest as needed (52), thereby limiting their generalizability to more
healthy samples. Accordingly, these studies were excluded from the current
analyses. For two trials in which the method of randomization was unclear
(39,66), we attempted to contact the respective authors and were able to
confirm that one trial followed a true randomization scheme (39). Results
were unchanged when the remaining study was excluded and we, therefore,
included this trial in all analyses (66).
Assessment of Study Quality
Two raters (P.J.S., B.M.H.) independently extracted information from
each article, using an identical review protocol, which included study iden-
tifiers (e.g., authors’ names, year of publication, publishing journal), duration
of treatment, intensity of exercise, modality of exercise, blinding of assess-
ment personnel to treatment status, during assessments, intention-to-treat
(ITT) analyses, and time of follow-up assessment. ESs were assessed inde-
pendently. Interrater reliability was assessed for the outcome domains in
question (i.e., in each cognitive domain as well as for study characteristics).
For all areas, interrater reliability was found to be excellent (r ⬎ .90; Cohen’s
␬
⫽ 0.75).
Data Analysis
Neuropsychological test results were classified according to the cognitive
domains described by Lezak and colleagues (67). We considered neurocognitive
tests that could be classified in the following categories: attention and processing
speed (the sustained focus of cognitive resources with selective concentration and
rapid processing of information (67,68), executive function (a set of cognitive
skills responsible for the planning, initiation, sequencing, and monitoring of
complex, goal-directed behavior), working memory (short-term storage and ma-
nipulation of information), and declarative memory (retention, recollection,
and recognition of previously encountered information, hereafter referred
to only as “memory”). We considered including “complex processing
speed” as a measure of executive function as in previous analyses (9), but
results were unchanged regardless of the classification of this test.
Analyses were conducted, using Comprehensive Meta Analysis software
(Biostat, Englewood, New Jersey). Data were analyzed, using both fixed and
random effects models and Cohen’s G for between-group differences (69). Fixed
effects analysis assumes that all studies are drawn from the same population, such
that differences in treatment effects across studies are attributed to sampling and
methodological variability (i.e., error variance). In contrast, random effects anal-
ysis allows for the possibility that studies are drawn from different populations,
such that differences across studies may be due to unidentified sources of
variation and provides a more conservative estimate of treatment effects (70).
However, because results did not differ between fixed and random effects
analyses and because random effects are generally recommended for examining
treatment effects in meta-analytic studies (70), we have presented the random
effects findings only. In trials reporting multiple effect sizes within the same
neurocognitive domain, data were collapsed by averaging all ESs within each
neurocognitive domain for each study, such that each study produced no more
than one ES per domain. For the purposes of the study quality analyses, treatment
effects were collapsed for each study for all neurocognitive domains. In addition,
two trials in our literature search produced multiple publications in either peer-
reviewed journals (71–73) or book chapters (74,75) that were combined for the
purposes of analysis. Homogeneity of treatment effects was assessed, using the Q
statistic. Three trials collected neurocognitive data at multiple time points in
which participants continued to receive treatment (30,73,76). However, in only
one study were the effects of treatment uncontaminated by crossover between
groups (30). For this study only (30), we chose data from the longest follow-up
assessment for inclusion in our analyses, although results were unchanged when
other time points were examined.
Exploratory sensitivity analyses (77,78) were conducted to investigate
sample characteristics that may have moderated the effects of treatment on
neurocognitive outcomes. Specifically, three trial characteristics were
examined: duration, intensity, and mode of exercise intervention. We also
examined two important methodological characteristics associated with meth-
odological quality: blinding of assessors of neurocognitive outcomes and use
of ITT analyses. As an additional analysis, we examined whether treatment
effects varied by cognitive status of participants at baseline (i.e., “nonim-
paired” or MCI; patients with dementia [Alzheimer’s disease] were excluded)
and age of study participants.
RESULTS
Our initial literature search yielded 5538 potentially rele-
vant studies, 68 of which were retrieved for full-text review.
Twenty-nine studies incorporating data from 2049 participants
met inclusion criteria and were included in the present anal-
yses (Table 1), including data for 1024 experimental partici-
pants and 997 controls. Two hundred thirty-four ESs were
available for analysis. Trials ranged in duration from 6 weeks
(79) to 18 months (30). As shown in Table 1, the primary
exercise modality was brisk walking and/or jogging and control
groups were typically assigned to a wait-list control, although
P. J. SMITH et al.
240 Psychosomatic Medicine 72:239–252 (2010)

TABLE 1. Randomized Controlled Trials Examining the Effect of Aerobic Exercise on Neurocognitive Function
Author / Year Sample Intervention Instruments
Methodological
Characteristics
Hedge’s G
Bakken, 2001 (103) 15, older adults, ages
72 to 91
Duration: 8 wks
Frequency: 30 min, 3/wk
Intensity:---
Combined Strength
Training: Y
MCI: N
Imaging (Verbal Fluency), Visual
Discrimination, Raven’s
Progressive Matrices, Short-Term
Retention, Addition, Perception of
Ambiguous Stimuli
Attrition: 0%
ITT: N
Blinding: N
AT ⫽ .169
Blumenthal, 1989 (72)
& Madden, 1989 (71)
101, sedentary, ages
60 to 83
Duration: 16 wks
¥
Frequency: 40 min, 3/wk
Intensity: 70% HRR
Combined Strength
Training: N
MCI: N
Finger Tapping, Benton Revised
Visual Retention Test, Digits
Forward, Digits Backward,
Selective Reminding Test, Randt
Memory Test – Short Story, TMT-
B, Digit Symbol, Ruff2&7Test,
Stroop Color, Stroop Color-Word
Interference, Nonverbal Fluency
Test, Verbal Fluency Test
Attrition: 8%
ITT:Y
Blinding: Y
AT ⫽ .218
EX ⫽⫺.025
WM ⫽ .114
ME ⫽⫺.066
Emery, 1990 (110) 48, “inner-city
cohort”, ages 61 to
86
Duration: 12 wks
Frequency: 60 min, 3/wk
Intensity: 70% HRR
Combined Strength
Training: Y
MCI: N
Digit Symbol, Digit Span, Word
Copy, Number Copy
Attrition:10%
ITT: N
Blinding: N
AT ⫽ .028
EX ⫽⫺.043
WM ⫽ .023
Emery, 1998 (111) 79, with stable COPD,
age range not
reported M ⫽ 67
Duration: 10 wks
¥
Frequency: 45 min, 3/wk
Intensity:---
Combined Strength
Training: Y
MCI: N
Verbal Fluency, Digit Vigilance,
Finger Tapping, TMT-A, TMT -B,
Digit Symbol
Attrition: 5%
ITT: N
Blinding: N
AT ⫽ .075
EX ⫽ .325
Fabre, 2002 (112) 32, healthy elderly
adults, ages 60 to
76
Duration: 8 wks
Frequency: 45 min, 2/wk
Intensity:---
Combined Strength
Training: N
MCI: N
Wechsler Memory Scale Attrition: 0%
ITT: N
Blinding: N
EX ⫽⫺.188
WM ⫽ .878‡
ME ⫽⫺.339
Hassmen, 1992 (39) 32, all women, ages
55 to 75
Duration: 12 wks
Frequency: 20 min, 3/wk
Intensity: 9–13 RPE
Combined Strength
Training: N
MCI: N
Digit Span, Face Recognition,
Simple Reaction Time, Choice
Reaction Time
Attrition: 7%
ITT: N
Blinding: N
AT ⫽ .179
EX ⫽ .167
WM ⫽ .204
ME ⫽⫺.145
Hawkins, 1992 (66) 40, sedentary, ages 63
to 82
Duration: 10 wks
Frequency: 45 min, 3/wk
Intensity:---
Combined Strength
Training: N
MCI: N
Single-Task Reaction Time, Dual-
Task Reaction Time, Difference
Between Single-Task And Dual-
Task Reaction Time
Attrition: 10%
ITT: N
Blinding: N
AT ⫽⫺.243
EX ⫽ .047
Hoffman, 2008 (31) 153, sedentary and
depressed, ages 41
to 87
Duration: 16 wks
Frequency: 45 min, 3/wk
Intensity: 70–85% HRR
Combined Strength
Training: N
MCI: N
Logical Memory, Verbal Paired
Associates, Digit Span, Animal
Naming, COWAT, Stroop Color
Word, Ruff2&7Test, Digit
Symbol, TMT B-A
Attrition: 28%
ITT: Y
Blinding: Y
AT ⫽ .277
EX ⫽ .172
WM ⫽⫺.031
ME ⫽ .072
Khatri, 2001 (113) 84, sedentary and
depressed, ages 50
to 72
Duration: 17 wks
Frequency: 45 min, 3/wk
Intensity: 70–85% HRR
Combined Strength
Training: N
MCI: N
Visual Reproduction, Stroop Color-
Work Interference, Digit Span,
TMT-A, Digit Symbol, Stroop
Color, Stroop Word, TMT-B,
Logical Memory
Attrition: 25%
ITT: Y
Blinding: Y
AT ⫽ .121
EX ⫽ .291
WM ⫽⫺.047
ME ⫽ .186
Kramer, 1999 &
2002 (74, 75)
124, sedentary, ages
60 to 75
Duration: 26 wks
Frequency: 40 min, 3/wk
Intensity: 50–70% HRR
Combined Strength
Training: N
MCI: N
Reaction Time Tests: Switching
Trials, Non-Switching Trials,
Incompatible Trials, Compatible
Trials, Interference Effect
(Difference Between Compatible
Trials and Incompatible Trials),
Stop Signal Trials, Simple
Reaction-Time Trials
Attrition: 29%
ITT:N
Blinding: N
AT ⫽ .091
EX ⫽ .196
WM ⫽⫺.101
ME ⫽ .156
(Continued)
AEROBIC EXERCISE AND NEUROCOGNITION
241Psychosomatic Medicine 72:239–252 (2010)

TABLE 1. Continued
Author/Year Sample Intervention Instruments
Methodological
Characteristics
Hedge’s G
Lautenschlager,
2008 (30)
170, elderly adults
with MCI, age M ⫽
69
Duration: 72 wks
¥
Frequency: 50 min, 3/wk
Intensity:---
Combined Strength
Training: N
MCI: Y
Word list recall (immediate and
delayed), Digit Symbol, COWAT
Attrition: 19%
ITT: Y
Blinding: Y
AT ⫽ .083
EX ⫽⫺.071
ME ⫽ .322**
Masley, 2008 (114) 56, adults, age M ⫽
45
Duration: 10 wks
Frequency: 5/wk
Intensity: 70–85% MHR
Combined Strength
Training: Y
MCI: N
CNS Vital Signs (verbal memory,
symbol digit coding, the Stroop
test, shifting attention,
continuous performance)
Attrition: 16%
ITT: N
Blinding: N
(computerized)
AT ⫽⫺.158
EX ⫽ .487‡
Moul, 1995 (115) 30, sedentary, ages 65
to 72
Duration: 8 wks
Frequency: 35 min, 5/wk
Intensity: 60–65% HRR
Combined Strength
Training: N
MCI: N
Ross Information Processing
Assessment Subtests:
Organization, Auditory
Processing, Immediate Memory,
Recent Memory, Temporal
Orientation, Problem Solving/
Abstract Reasoning
Attrition: 0%
ITT: N
Blinding: N
EX ⫽ .780‡
ME ⫽ .351
Munguia-Izquierdo,
2008 (116)
60, middle-aged
women with
fibromyalgia, ages
18 to 60
Duration: 16 wks
Frequency: 50 min, 3/wk
Intensity: 50–80% MHR
Combined Strength
Training: N
MCI: N
Paced Auditory Serial Addition Task
(PASAT)
Attrition: 12%
ITT: Y
Blinding: Y
AT ⫽ .922***
Oken, 2004 (117) 69, multiple sclerosis,
M ⫽ 49
Duration: 26 wks
Frequency: 90 min, 1/wk
Intensity:---
Combined Strength
Training: N
MCI: N
Stroop Color-Word test, Simple
Reaction Time, Complex Reaction
Time, Attentional Shift Task,
PASAT, Logical Memory, WAIS
Similarities
Attrition ⫽ 12%
ITT: N
Blinding: Y
AT ⫽ .074
EX ⫽ .133
WM ⫽⫺.354
ME ⫽ .000
Oken, 2006 (118) 135, healthy adults,
ages 65 to 85
Duration: 26 wks
Frequency: 60 min, 1/wk
Intensity: 70% HRR
Combined Strength
Training: N
MCI: N
Stroop Interference, Word List
Recall, Letter-Number
Sequencing, Covert Orienting,
Divided Attention, Set Shifting,
Simple Reaction time, Complex
Reaction time
Attrition: 13%
ITT: N
Blinding: Y
AT ⫽⫺.132
EX ⫽⫺.034
WM ⫽⫺.029
ME ⫽⫺.055
Okumiya, 1996 (29) 42, healthy older
adults, ages 75 to
87
Duration: 24 wks
Frequency: 60 min, 3/wk
Intensity:---
Combined Strength
Training: Y
MCI: N
MMSE, Hasegawa Dementia Scale,
Visuospatial Cognitive
Performance Test
Attrition: 0%
ITT: N
Blinding: N
AT ⫽ .938**
Panton, 1990 (119) 39, healthy untrained
older adults, ages 70
to 79
Duration: 26 wks
Frequency: 45 min, 3/wk
Intensity: 75% HRR
Combined Strength
Training: N
MCI: N
Reaction time, Speed of Movement
Time
Attrition: 14%
ITT: N
Blinding: N
AT ⫽ .111
Perri, 1984 (121) 42, healthy older
adults, ages 60 to
79
Duration: 15 wks
Frequency: 30 min, 3/wk
Intensity: 40–50% HRR
Combined Strength
Training: N
MCI: N
Rey Auditory Verbal Learning Task Attrition: 41%
ITT: N
Blinding: N
ME ⫽ .261
Pierce, 1993 (120) 90, middle-aged adults
with hypertension,
ages 29–59
Duration: 16 wks
Frequency: 50 min, 3/wk
Intensity: 70% HRR
Combined Strength
Training: N
MCI: N
Digit Symbol, Stroop Color Word
test, Digit Span, TMT-B,
Sternberg Memory Search Task
(Slope and Y-intercept), Verbal
Paired Associates, Logical Memory
(immediate and delayed), Figural
Memory (immediate and delayed)
Attrition: 7%
ITT: Y
Blinding: Y
AT ⫽ .249
EX ⫽ .126
WM ⫽⫺.283
ME ⫽ .233
(Continued)
P. J. SMITH et al.
242 Psychosomatic Medicine 72:239–252 (2010)

TABLE 1. Continued
Author/Year Sample Intervention Instruments
Methodological
Characteristics
Hedge’s G
Russell, 1982 (122) 45, sedentary older
adults, ages 55 to
70
Duration: 16 wks
Frequency: 45 min, 3/wk
Intensity:---
Combined Strength
Training: N
MCI: N
Simple Reaction Time, Complex
Reaction Time
Attrition: 4%
ITT: N
Blinding: N
AT ⫽ .214
EX ⫽ .081
Scherder, 2005 (79) 43, elderly adults with
MCI, ages 76 to 94
Duration: 6 wks
Frequency: 30 min, 3/wk
Intensity:---
Combined Strength
Training: N
MCI: Y
Category Naming, TMT-A, TMT-B,
Digit Span, Visual Memory Span,
Rivermead Behavioral Memory
Test (Faces and Pictures), Verbal
Learning and Memory Test:
Direct Recall, Delayed Recall, and
Recognition
Attrition: 7%
ITT: N
Blinding: Y
EX ⫽ .441
WM ⫽ .037
ME ⫽ .413
Smiley-Oyen, 2008 (123) 57, older adults, ages
65–79
Duration: 40 wks
Frequency: 25–30 min, 3/wk
Intensity: 65–80% HRR
Combined Strength
Training: N
MCI: N
Stroop Test, Go-No-Go Test, Simple
Reaction Time, Choice Reaction
Time, Wisconsin Card Sorting
Test
Attrition: 7%
ITT: N
Blinding: N
AT ⫽ .234
EX ⫽⫺.092
Stroth, 2009 (124) 28, young adults, age
M ⫽ 20
Duration: 6 wks
Frequency: 30 min, 3/wk
Intensity: 70–100% aerobic
threshold
Combined Strength
Training: N
MCI: N
Digit Symbol Substitution Test, Rey
Auditory Verbal Learning Test,
Stroop Test
Attrition: 22%
ITT: N
Blinding: Y
AT ⫽⫺.123
ME ⫽ .650‡
Wallman, 2004 (125) 61, adults with chronic
fatigue syndrome,
ages 16 to 74
Duration: 12 wks
Frequency: increased
progressively Intensity: based
on target HR
from treadmill testing
Combined Strength
Training: N
MCI: N
Stroop Test (82 questions) Stroop
Test (95 questions)
Attrition: 10%
ITT: N
Blinding: Y
EX ⫽ .479*
Whitehurst, 1991 (126) 14, sedentary older
women, ages 61 to
73
Duration: 8 wks
Frequency: 35 min, 3/wk
Intensity:---
Combined Strength
Training: N
MCI: N
Simple Reaction Time, Choice
Reaction Time
Attrition: 0%
ITT: N
Blinding: N
AT ⫽⫺.551
EX ⫽⫺.609
Williams, 1997 (104) 187, all women, age M
⫽ 72
Duration: 42 wks
Frequency: 35 min, 2/wk
Intensity:---
Combined Strength
Training: Y
MCI: N
Digit Span, Picture Arrangement,
Cattell’s Matrices
Attrition: 20%
ITT: N
Blinding: N
AT ⫽ .501**
EX ⫽ .189
WM ⫽ .348*
Williamson, 2009 (34) 102, elderly adults,
ages 70–89 years
Duration: 52 wks
Frequency: 45 min, 1–2/wk
Intensity:---
Combined Strength
Training: Y
MCI: N
Digit Symbol, Modified Stroop Test,
3MSE, Rey Auditory Verbal
Learning Test
Attrition: 10%
ITT: N
Blinding: Y
AT ⫽ .206
EX ⫽ .026
ME ⫽ .011
van Uffelen, 2008 (33) 152, elderly adults
with MCI, age M ⫽
75
Duration: 52 wks
Frequency: 60 min, 2/wk
Intensity: ⬎3 METs
Combined Strength
Training: N
MCI: Y
Digit Symbol, Stroop Color Word
Test,Verbal Fluency, Auditory
Verbal Learning Test
Attrition: 9%
ITT: Y
Blinding: Y
AT ⫽⫺.10
EX ⫽⫺.04
ME ⫽⫺.03
*** p ⬍ .001; ** p ⬍ .01; * p ⬍ .05; ‡ p ⬍ .10; AT ⫽ attention and processing speed; EX ⫽ executive function; MET ⫽ metabolic equivalent, WM ⫽ working
memory; MCI ⫽ Mild Cognitive Impairment, ME ⫽ memory; HRR ⫽ Heart Rate Reserve; MHR ⫽ maximum heart rate; RPE ⫽ Ratings of Perceived Exertion;
TMT ⫽ Trail Mating Test; ¥ ⫽ indicates multiple time points of data.
AEROBIC EXERCISE AND NEUROCOGNITION
243Psychosomatic Medicine 72:239–252 (2010)