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Journal of Aging Research
Volume , Article ID , pages
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Research Article
Physical Activity Improves Verbal and Spatial Memory
in Older Adults with Probable Mild Cognitive Impairment:
A 6-Month Randomized Controlled Trial
Lindsay S. Nagamatsu,1Alison Chan,2Jennifer C. Davis,2B. Lynn Beattie,3,4 Peter Graf,1
Michelle W. Voss,5Devika Sharma,2and Teresa Liu-Ambrose2,4
1DepartmentofPsychology,UniversityofBritishColumbia(UBC),2136WestMall,Vancouver,BC,CanadaV6T1Z4
2DepartmentofPhysicalerapy,UniversityofBritishColumbia(UBC),212-2177WesbrookMall,
Vancouver,BC,CanadaV6T1Z3
3Alzheimer Clinic, G37 Purdy Pavilion, UBC Hospital, University of British Columbia (UBC), 2211 Wesbrook Mall, Vancouver, BC,
Canada V6T 2B5
4Brain Research Centre, University of British Columbia (UBC), 2211 Wesbrook Mall, Vancouver, BC,
Canada V6T 2B5
5Department of Psychology, e University of Iowa, E11 Seashore Hall, Iowa City, IA 52242-1409, USA
Correspondence should be addressed to Teresa Liu-Ambrose; tlambrose@exchange.ubc.ca
Received November ; Accepted January
Academic Editor: Louis Bherer
Copyright © Lindsay S. Nagamatsu et al. is is an open access article distributed under the Creative Commons Attribution
License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly
cited.
We report secondary ndings from a randomized controlled trial on the eects of exercise on memory in older adults with probable
MCI. We randomized women aged – years with subjective memory complaints into one of three groups: resistance training,
aerobic training, or balance and tone (control). All participants exercised twice per week for six months. We measured verbal
memory and learning using the Rey Auditory Verbal Learning Test (RAVLT) and spatial memory using a computerized test,
before and aer trial completion. We found that the aerobic training group remembered signicantly more items in the loss aer
interference condition of the RAVLT compared with the control group aer six months of training. In addition, both experimental
groups showed improved spatial memory performance in the most dicult condition where they were required to memorize the
spatial location of three items, compared with the control group. Lastly, we found a signicant correlation between spatial memory
performance and overall physical capacity aer intervention in the aerobic training group. Taken together, our results provide
support for the prevailing notion that exercise can positively impact cognitive functioning and may represent an eective strategy
to improve memory in those who have begun to experience cognitive decline.
1. Introduction
Cognitive decline is one of the most pressing health care
issues of the st century. Currently worldwide, one new
case of dementia is detected every seven seconds []and
the number of people aected is projected to be over
million by []. us, the societal value of developing
eective intervention strategies cannot be overstated [].
To date, pharmacological interventions for dementia have
remained medically challenging at best. As a result, there has
been growing interest in exercise training as an alternative
intervention strategy.
e primary aim of our current study was to investigate
the ecacy of exercise as an intervention strategy to improve
memory performance in older adults who have already
begun to experience cognitive decline—namely, those with
mild cognitive impairment (MCI). MCI is characterized
by cognitive decline that is greater than expected for an
individual’s age and education level, but does not signicantly
interfere with everyday function (i.e., instrumental activities
Journal of Aging Research
of daily living) []. Importantly, MCI is a well-recognized risk
factor for dementia; longitudinal studies report that seniors
with MCI develop Alzheimer’s disease at a rate of –%
annually [,], compared to -% of seniors without MCI
[]. us, MCI represents a critical window of opportunity
to intervene and alter the trajectory of both cognitive and
functional decline in seniors.
Exercise is a promising strategy for improving cognitive
functions. Previous research has found that both resistance
training [,] and aerobic training [] positively impact
cognitive functioning and result in functional plasticity in
healthy older adults. Furthermore, emerging evidence also
suggests that exercise training has cognitive benets for
seniors with MCI. For example, a -week home-based
physical activity program improved performance on the
Alzheimer Disease Assessment Scale-Cognitive Subscale in
seniors with probable MCI []. Additionally, a six-month
aerobic training program improved selective attention and
conict resolution, processing speed, and verbal uency in
senior women with amnestic MCI [].
Expanding upon the existing body of knowledge on
exercise and cognitive functions, we found that twice-weekly
progressive resistance training in our six-month interven-
tion improved associative memory—or the memorization of
two items in conjunction—in senior women with probable
MCI []. ese ndings were further corroborated by our
neuroimaging results, where resistance training was asso-
ciated with increased activation over time in key cortical
regions that subserve associative memory. Importantly, other
research groups have found complementary evidence for
a relationship between physical activity and memory in
seniors with MCI []. However, a comparison has not been
conducted between resistance and aerobic training for their
propensity to improve various forms of memory in older
adults who are showing signs of memory decline.
For our study reported here, we analyzed the secondary
outcome measures of our randomized controlled trial that
was previously published []. Our current analysis was
primarily designed to examine the ecacy of both resistance
training and aerobic training to improve memory perfor-
mance in senior women with probable MCI. To this end,
we examined the impact of exercise on two distinct forms
of memory: () verbal memory and learning and () spatial
memory. e second aim of our study was to determine
whether memory performance at the end of the trial might
be associated with physical performance measures. While
research on the eects of resistance training on cognitive
function has been limited, preliminary evidence does suggest
that dierent forms of exercise (e.g., aerobic versus resistance
training) alter distinct cognitive processes [,]. Consis-
tent with this idea, Cassilhas and colleagues []recently
reported dierences in underlying molecular mechanisms
between the two types of exercise for how they may improve
cognitive function; whereas resistance training appeared to
increase levels of serum IFG-, aerobic training increased
levels of brain-derived neurotrophic factors (BDNF) in the
hippocampus. erefore, we hypothesized that both types
of exercise training would yield benecial—although poten-
tially divergent—impacts on memory.
2. Methods
2.1. Study Design. We conducted a -week, single-blinded,
randomized trial of exercise (NCT) with assess-
ments at baseline, mid-point, and trial completion. Details of
the trial have been reported elsewhere [].
2.2. Participants. Our study only included women due to
sex dierences in cognitive response to exercise []. From
April to August , we recruited participants using
advertisements in local media and a memory clinic. Individ-
uals were screened by a standardized telephone interview and
by a -minute in-person assessment. Women who lived in
Vancouver, Canada, were eligible for study entry if they ()
were aged to years; () were living independently in
their own home; () scored ≥/ on the Mini-Mental State
Examination (MMSE); () scored </ on the Montreal
Cognitive Assessment (MoCA) []; () answered “yes” to the
question“doyouhaveanydicultywithyourmemory?”[];
() scored ≥/ on the Lawton and Brody []Instrumental
Activities of Daily Living; () had a visual acuity of at least
/, with or without corrective lenses; and () obtained
their physician’s clearance to start a supervised exercise
program. We excluded those who () had a current medical
condition for which exercise is contraindicated; () had par-
ticipated regularly in resistance training or aerobic training
in the last six months; () had a neurodegenerative disease
and/or stroke; () had a diagnosed psychiatric condition (e.g.,
depression); () had a diagnosis of dementia of any type; ()
did not speak and understand English uently; or () were on
oestrogen replacement therapy.
In Figure ,theCONSORT(ConsolidatedStandardsof
Reporting Trial) owchart shows the number and distri-
bution of participants. Ethical approval was obtained from
the Vancouver Coastal Health Research Institute and the
University of British Columbia’s Clinical Research Ethics
Board. All participants provided written informed consent.
2.3. Descriptive Variables. Current level of physical activity
was determined by the Physical Activities Scale for the
Elderly (PASE) self-report questionnaire []. e -item
Geriatric Depression Scale [] screened for depression. e
Functional Comorbidity Index was calculated to estimate the
degree of comorbidity associated with physical functioning
[]. We used the Lawton and Brody []Instrumental
Activities of Daily Living Scale to subjectively assess ability
to perform daily activities.
2.4. Verbal Memory and Learning. e Rey Auditory Verbal
Learning Test (RAVLT) [] assessed verbal memory and
learning. Participants were read a list of common words
ve times. Immediately aer each time, they were required
to recall as many words as possible. Aer the h trial,
an interference list was presented, aer which participants
had to spontaneously recall the original words. Finally, par-
ticipants were required to spontaneously recall the original
words aer a minute delay. Scores were calculated as
thetotalnumberofwordsrecalled()acrossthevetrials
Journal of Aging Research
Flyer advertisement in a
hospital memory clinic
General newspaper,
television, flyer, radio, and
email advertisements
Telephone screen
285 screened
111 excluded
58 eligible based on phone screen but no longer interested
In person screening session
116 screened
25 excluded
4 eligible but no longer interested
87 consented and booked for baseline assessment
Baseline assessment
86 completed the assessment
1 withdrew
86 randomized
2𝑥/week resistance training
𝑛=28 2𝑥/week balance and tone
𝑛=28 2𝑥/week walking program
𝑛=30
1 withdrew 6withdrew
(5 =no interest;
Midpoint assessment
Final assessment Final assessment Final assessment
Midpoint assessment Midpoint assessment
26 completed 28 completed 23 completed
26 completed 27 completed 24 completed
1 did not complete
midpoint assessment
1did not complete
midpoint assessment
1did not complete nal
assessment
1did not complete
nal assessment
77 completed trial and included in analysis
(1=no interest)
(1=anxiety)
(1 =health)
(1 =health) (1 =health)
1=health)
(1=weather)
F : e CONSORT (Consolidated Standards of Reporting Trials) owchart.
(total acquisition); () aer the interference list (recall aer
interference); () on the h trial minus aer the interference
(loss aer interference); and () aer the delay (long delay free
recall).
2.5. Spatial Memory. Spatial memory was assessed using a
computerized task developed in-house by one of our co-
authors along with her collaborators. is task was chosen
because it has previously been found to modulate with
physical activity [–] and allows for the collection of
reaction times and accuracy—rather than just working mem-
ory span which other spatial memory tasks provide. Our
spatialmemorytaskrequiredparticipantstorecallthespatial
location of dots presented on a screen. Specically, one, two,
or three dots appeared at randomly selected locations on the
screen for ms. Next, a xation-cross appeared for s. At
theendofthedelay,asingleredtestdotwaspresentedon
the screen, either at the same location as one of the previous
black dots (match), or at a new location (nonmatch). Subjects
Journal of Aging Research
T
Variabl e aBAT
(𝑛=28)
AT
(𝑛=30)
RT
(𝑛=28)
Total
𝑁=86
Mean (SD) Mean (SD) Mean (SD) Mean (SD)
Age, years . (.) . (.) . (.) . (.)
Height, cm . (.) . (.) . (.) . (.)
Weight, kg . (.) . (.) . (.) . (.)
Physical activity scale for the elderly . (.) . (.) . (.) . (.)
Education, No (%)
Less than grade () (.) ( (.)
Grade to without certicate or diploma (.) (.) (.) (.)
High school certicate or diploma (.) (.) (.) (.)
Trades or professional certicate or diploma (.) (.) (.) (.)
University certicate or diploma (.) (.) (.) (.)
University degree (.) (.) (.) (.)
Geriatric depression scaleb. (.) . (.) . (.) . (.)
Functional comorbidities indexc. (.) . (.) . (.) . (.)
Instrumental activities of daily livingd. (.) . (.) . (.) . (.)
Montreal cognitive assessmente. (.) . (.) . (.) . (.)
Minimental state examinationf. (.) . (.) . (.) . (.)
Exercise class compliance, % (.) (.) (.) (.)
Abbreviations: BAT: balance and tone; AT: aerobic training; RT: resistance training.
aUnless otherwise indicated, data are expressed as mean (SD). Percentages (%) have been rounded and may not total .
bMaximum was points.
cMaximum was points.
dMaximum was points.
eMaximum was points.
fMaximum was points.
were required to indicate whether the red test dot was a match
or a nonmatch to any of the previously presented black dots
by pressing the designated key on a computer keyboard (“x”
= nonmatch; “m” = match). Participants were instructed to
respondasquicklyandaccuratelyaspossible.eentiretask
consistedoftrials(trialsforeachsetsize,dividedinto
match and nonmatch conditions). Participants were
provided with practice trials prior to beginning the test to
ensure they understood the task instructions. Reaction times
and accuracy were recorded.
2.6. Choice Reaction Time. Choice reaction times were col-
lectedtouseasacovariateinourstatisticalanalysesfor
computerized tasks measuring reaction times to account for
dierences in basic processing speed secondary to memory
performance []. Participants were required to indicate
whetheranumber(,,,,,,,)presentedonacomputer
screen was higher or lower than the number “”. Numbers
were presented individually for ms in the centre of the
screen,andthesamenumberdidnotrepeattwiceinarow.
Usingonehand,theywererequiredtopressonebuttonwith
theirindexngerifthecorrectanswerwas“higher”thanve
and another button with their middle nger if the number
was “lower” than ve. Participants were instructed to respond
as quickly and accurately as possible.
2.7. Physical Performance. General balance and mobility was
assessed using the Short Physical Performance Battery, which
is a composite score of the following tasks: () tandem
standing; () four-metre walk (gait speed); and () chair
stands. General cardiovascular capacity was assessed using
the Six-Minute Walk Test, where the total distance walked
at participants’ usual pace in six minutes was measured in
metres.
2.8. Randomization. e randomization sequence was gener-
ated by (http://www.randomization.com) and was concealed
until interventions were assigned. is sequence was held
independently and remotely by the Research Coordinator.
Participants were enrolled and randomized by the Research
Coordinator to the twice-weekly exercise groups: resistance
training (RT), aerobic training (AT), or balance and tone
(BAT).
2.9. Exercise Intervention. e exercise protocol has been
reported elsewhere []. Briey, classes began one month
aer baseline assessments and were held at a fully equipped
gym in a research centre. Classes were led by certied
tness instructors who received additional training from the
study investigators. e classes were minutes in duration
(-minute warm-up, minutes of core content, and -
minute cool-down). Attendance was recorded daily, which
Journal of Aging Research
was used to calculate compliance (i.e., percentage of total
classes attended). Strategies were implemented to promote
participant engagement [,].
2.9.1. Resistance Training. For the RT program, both a
Keiser Pressurized Air system and free weights were used
[]. e Keiser-based exercises consisted of biceps curls,
triceps extension, seated row, latissimus dorsi pull downs,
leg press, hamstring curls, and calf raises. e intensity of
the training stimulus was at a work range of six to eight
repetitions (two sets). e training stimulus was subsequently
increased using the RM method—when two sets of six
to eight repetitions were completed with proper form and
without discomfort. Other key strength exercises included
minisquats, minilunges, and lunge walks.
2.9.2. Aerobic Training. e AT program was an outdoor
walking program. e intensity of the training stimulus was
at approximately % of one’s age specic target heart rate
(i.e., heart rate reserve; HRR) and progressed over the rst
weeks to the range of % to % of HRR. Exercise intensity
was monitored through heart rate monitors. Participants also
monitored the intensity of their workouts by the Borg’s Rating
of Perceived Exertion [] and the “talk” test [,].
2.9.3. Balance and Tone. e BAT program consisted of
stretching exercises, range of motion exercises, balance exer-
cises, functional sand relaxation techniques []. Other than
bodyweight, no additional loading (e.g., hand weights, etc.)
was applied. is group served to control for confounding
variables such as physical training received by traveling to the
training centres, social interaction, and changes in lifestyle
secondary to study participation.
2.10. Adverse Eects. Participants were questioned about the
presence of any adverse eects, such as musculoskeletal pain
or discomfort, at each exercise session. Instructors monitored
participants for symptoms of angina and shortness of breath
during the exercise classes.
2.11. Statistical Analysis. All analyses were “full analysis set”
[] (dened as the analysis set which is as complete and as
close as possible to the intention-to-treat ideal of including
all randomized participants). Data were analyzed using IBM
SPSS STATISTICS (Version ).
Performance on the RAVLT was measured using univari-
ate ANOVAs for each outcome measure, with two planned
simple contrasts to assess dierences between () RT versus
BAT and () AT versus BAT. Baseline scores were entered as
covariates. For the spatial memory task, repeated measures
ANOVAs were performed to examine changes over the
course of the trial in both reaction time and accuracy,
with number of items (one, two, or three) as the within-
subjects factor and group as the between-subjects factor. e
reaction time analysis included choice reaction time as a
covariate to account for dierences in processing speed [].
Bivariate Pearson correlations were calculated to examine
the relationship between memory and physical performance
0
0.5
1
RT AT BAT
−0.5
−1
−1.5
−2
Change in loss aer interference (trial completion −baseline)
F : Change between baseline and trial completion in loss
aer interference on the RAVLT as a function of exercise group. e
AT group showed signicantly more change compared to the BAT
group. Error bars represent standard error of the mean.
at trial completion within each group. For all analyses the
overall alpha was set at 𝑃 ≤ 0.05.
3. Results
3.1. Descriptive Variables, Physical Activity, and Participants.
In this trial, participants were recruited and randomized
(Figure ). Baseline demographic and characteristics of the
participants are shown in Table .Physicalactivitylevels
(PASE scores) did not dier signicantly between the groups
at midpoint (𝑃 = 0.93)ortrialcompletion(𝑃 = 0.67). Of the
participants, completed the -week trial. e number
of dropouts was the greatest in the AT group (Figure ).
3.2. Verbal Memory and Learning. Ta b l e shows the baseline,
mid-point, and trial completion results for verbal memory
andlearningperformance.FortheRAVLT,therewereno
signicant between-group dierences at trial completion in
totalacquisition,recallaerinterference,andlongdelayfree
recall (all P’s >.). However, there was a signicant dif-
ference in loss aer interference at trial completion between
theATandBATgroups,𝑃 = 0.04 (Figure ). Conversely,
the RT and BAT contrast for loss aer interference was
nonsignicant, 𝑃 = 0.20.Overall,lossaerinterferencewas
reducedby.%and.%intheATgroupandtheRT
group, respectively. In contrast, the BAT group demonstrated
a .% increase in loss aer interference. e improvement
observed in the AT group was not present at mid-point, 𝑃=
0.71.
3.3. Spatial Memory. Ta b l e shows the baseline, mid-point,
and trial completion results for reaction time and accuracy
Journal of Aging Research
T : Mean values (SDs) for RAVLT p e r f o r m a n c e .
Variabl e Baseline Midpoint Final
Mean (SD) Mean (SD) Mean (SD)
RT 𝑛 = 25 𝑛 = 24 𝑛 = 25
Total acquisition . (.) . (.) . (.)
Recall aer interference . (.) . (.) . (.)
Loss aer interference . (.) . (.) . (.)
Long delay free recall . (.) . (.) . (.)
AT 𝑛 = 24 𝑛 = 23 𝑛 = 24
Total acquisition . (.) . (.) . (.)
Recall aer interference . (.) . (.) . (.)
Loss aer interference . (.) . (.) . (.)
Long delay free recall . (.) . (.) . (.)
BAT 𝑛 = 25 𝑛 = 24 𝑛 = 25
Total acquisition . (.) . (.) . (.)
Recall aer interference . (.) . (.) . (.)
Loss aer interference . (.) . (.) . (.)
Long delay free recall . (.) . (.) . (.)
Abbreviations: BAT: balance and tone; AT: aerobic training; RT: resistance training.
0
20
Change in reaction time
One item Two items ree items
RT
AT
BAT
−20
−40
−60
−80
−100
−120
(trial completion minus baseline)
F : Change between baseline and trial completion on the
spatial memory task as a function of number of items presented
and exercise group. Both the RT and AT groups showed improved
performance compared to the BAT group for the memorization of
three items. Error bars represent standard error of the mean.
on the spatial memory task. e exercise groups diered
in reaction time changes aer completion of the trial as a
function of number of items to be remembered. is was
evidenced by a signicant item by group interaction, F(,)
= ., 𝑃 = 0.05.Examiningtheplots(Figure ), the RT and
AT groups appear to have improved their reaction times for
memorizing the spatial location of three items more than the
BAT group. Notably, this between-groups dierence was not
present at mid-point, 𝑃 = 0.18. ere were no signicant
dierences between the exercise groups in accuracy for
−400 −300 −200 −100
0
0.5
1
1.5
2
2.5
3
3.5
0100200
SPPB score at trial completion
minus baseline
ree item reaction time at trial completion minus baseline
Aerobic training group
F : Signicant correlations between change in reaction time
performance on the spatial memory task and change in performance
on the SPPB for the AT group. SPPB performance was negatively
correlated with spatial memory reaction time, where better balance
and mobility were associated with faster reaction times.
spatial memory for either mid-point or trial completion (𝑃=
0.83 and ., resp.).
3.4. Correlations between Memory and Physical Performance.
Changes in physical performance as a function of exercise
group have been previously reported []. In this study,
faster reaction times at trial completion compared to baseline
during the three-item condition on the spatial memory task
were associated with better performance on the SPPB in the
AT gr oup ( Figure ). is was conrmed via a signicant neg-
ative correlation between the two variables, 𝑟(13) = −0.57,
𝑃 = 0.04. Spatial memory reaction times and SPPB were
not signicantly correlated in the RT or BAT groups (𝑃=
0.20 and ., resp.). Furthermore, reaction times were not
associated with performance on the Six-Minute Walk Test
(all P’s >.). ere were no signicant correlations between
Journal of Aging Research
T : Mean values (SDs) for spatial memory performance.
Variabl e Baseline Midpoint Final
Mean (SD) Mean (SD) Mean (SD)
RT 𝑛=19 𝑛=18 𝑛=19
Reaction time, ms
One item . (.) . (.) . (.)
Two items . (.) . (.) . (.)
ree items . (.) . (.) . (.)
Accuracya
One item . (.) . (.) . (.)
Two items . (.) . (.) . (.)
ree items . (.) . (.) . (.)
Choice reaction time, ms . (.) . (.) . (.)
AT 𝑛=17 𝑛=16 𝑛=17
Reaction time, ms
One item . (.) . (.) . (.)
Two items . (.) . (.) . (.)
ree items . (.) . (.) . (.)
Accuracy
One item . (.) . (.) . (.)
Two items . (.) . (.) . (.)
ree items . (.) . (.) . (.)
Choice reaction time, ms . (.) . (.) . (.)
BAT 𝑛=19 𝑛=19 𝑛=19
Reaction time, ms
One item . (.) . (.) . (.)
Two items . (.) . (.) . (.)
ree items . (.) . (.) . (.)
Accuracy
One item . (.) . (.) . (.)
Two items . (.) . (.) . (.)
ree items . (.) . (.) . (.)
Choice reaction time, ms . (.) . (.) . (.)
Abbreviations: BAT: balance and tone; AT: aerobic training; RT: resistance training.
aMaximum was ..
RAVLT performance and either of the physical performance
measures (all P’s >.).
3.5. Adverse Events. Adverse eects included episodes of
shortness of breath that resolved with rest (𝑛=2)and
noninjurous falls (𝑛=4).ResultsoftheChiSquaretest
indicated no signicant between-group dierences (𝑃=
0.54) in the proportion of participants reporting adverse
events.
4. Discussion
We analyzed our secondary data from a six-month inter-
vention to examine the eects of aerobic training and
resistance training on two distinct forms of memory. Our
specic aims were to evaluate whether either type of exercise
would improve verbal memory and learning and/or spatial
memory and to determine whether an association might exist
between postintervention memory performance and physical
measures. In this regard, we report three key ndings.
First, we found that twice-weekly aerobic training for six
months remembered signicantly more items in the loss aer
interference condition on the verbal memory test. Second,
our results suggest that both types of exercise improved
reaction times during the spatial memory test compared to
the control group. Last, spatial memory performance appears
to be positively associated with physical performance in the
aerobic training group aer the intervention. e results
of our present study extend those from our previous work
[], where we found that resistance training signicantly
improved associative memory. Within this context, several
noteworthy points of discussion follow.
To begin with, our nding that aerobic exercise signi-
cantly improved verbal memory and learning is consistent
with previous reports. Specically, Pereira and colleagues
Journal of Aging Research
[] found that three months of aerobic exercise improved
performance on the RAVLT. While the benets of aerobic
activity on verbal memory and learning in our study were
only observed aer six months—compared to three months
in the study by Pereira et al. [], dierences in study design
may account for this apparent discrepancy. For example,
participants in the study by Pereira et al. []wereyoung,
healthy adults who engaged in aerobic activity four times per
week;thisiscontrastedwitholderadultsinourstudywho
were already experiencing cognitive decline and exercised
twice per week. is suggests that a higher dose of exercise
may result in observable changes in memory more quickly.
It is worth mentioning that in our study, the resistance
training group also showed a greater reduction in loss aer
interference aer the trial compared with the control group,
although this change was not signicant. Nevertheless, future
studies with larger sample sizes may discover that resistance
training does yield similar benets to aerobic training for
verbal memory performance.
Second, we found that both of our experimental exercise
groups showed improved reaction time performance for
recalling the spatial location of three items, as compared to
the balance and tone group. Task performance on the spatial
memory test has been shown to systematically decline as a
function of load []. at the between-group dierence was
solely observed for three items—the most dicult condition
for the spatial memory task—suggests that exercise distinc-
tively improves higher-level cognitive processing required for
morecomplicatedtasks.esendingsdirectlysupportthose
from previous studies, where both resistance and aerobic
training improved executive functioning—such as selective
attention and conict resolution, as measured by the Stroop
task [,,].
ird, in light of our initial ndings regarding improved
associative memory performance aer six months of twice-
weekly resistance training, the results of our present study
suggest that dierent types of exercise may selectively target
distinct cognitive processes—and their underlying neural
correlates. To recapitulate, we previously reported that resis-
tance training resulted in improved associative memory
performance and increased functional activation in three
key regions of the cortex: the right lingual and occipital-
fusiform gyri and the right frontal pole []. In contrast,
here we found that both types of exercise training led to
im prov ed spat i a l m emory. Imp ortant l y, spatia l m e mory has
neural underpinnings in the hippocampus [,], thus
suggesting that both forms of exercise training may impact
hippocampal structure and/or function. Indeed, it has been
established that the hippocampus is the structure most
sensitive to exercise-induced change via neurogenesis and
cell proliferation. For example, aerobic exercise has been
found to increase hippocampal volume and levels of BDNF—
a neurotrophic factor involved in cell growth and survival
and memory promotion [].us,whiletherearemultiple
potential mechanisms to account for the relationship between
cognitive functions and physical activity, such as increased
cerebral blood ow [], reduced neuroinammation [],
and contribution of white matter hyperintensities [], we can
speculate that underlying changes in hippocampal structure
and/or function may be a mediating observed relationship
between spatial memory and physical performance.
Finally, the link between physical activity and cognitive
functioning is further supported by the signicant corre-
lation we have reported between our measure of overall
physical performance and spatial memory in the aerobic
training group. Notably, these results correspond to our
previous ndings that improvements in conict resolution
and selective attention, as measured by Stroop performance,
were signicantly correlated to improved gait speed aer
months of resistance training []. at these two studies
found relationships between dierent types of exercise (aer-
obic versus resistance training) and two dierent measures
of cognitive function further supports the notion presented
abovethatthetwotypesofexercisemaytargetdistinctmolec-
ular pathways []—and thus, modify dierent subtypes
of cognitive function. However, in combination, evidence
from these two studies demonstrate that higher levels of
physical performance are associated with better cognitive
performance. Given that there are multiple ways to improve
general physical performance levels, our results therefore
suggest that individuals may gain cognitive benets from a
wide variety of exercise options. Future work is needed to
explore this possibility.
e conclusions of our study are tempered by our exclu-
sion of men and those older or younger than – years
old. Additionally, our study was only powered to compare the
resistance training versus the control group and the aerobic
training versus the control group; therefore, we were unable
to directly compare changes in performance between our two
exercise groups. Hence, future research on how our results
may apply to the broader population with larger sample sizes
is warranted.
In sum, our study provides preliminary evidence that
multiple benets for memory can be observed aer six
months of exercise training. However, the mechanisms
behind how resistance training and aerobic training may dif-
ferentially impact cognition remain unclear; thus future work
should be aimed at further understanding the contribution
of each type of exercise to cognitive functioning, functional
plasticity, and brain structure. Furthermore, while our study
did nd performance improvements aer six months, we did
not see comparable changes aer only three months using a
twice-weekly exercise protocol. erefore, the dose-response
relationship of exercise needs to be elucidated so that future
recommendations for the most eective program can be
translated to health care practitioners and the public.
Disclosure
T. L. Ambrose had full access to all the data in the study
and takes responsibility for the integrity of the data and the
accuracy of the data analysis.
Conflict of Interest
All authors have no conict of interests to declare.
Journal of Aging Research
Acknowledgments
e Pacic Alzheimer’s Research Foundation provided fund-
ing for this study (to T. L. Ambrose). e authors thank the
instructors for their commitment to the participants’ health
and safety. T. L. Ambrose is a Michael Smith Foundation
for Health Research Scholar and a Canada Research Chair
in Physical Activity, Mobility, and Cognitive Neuroscience.
L. Nagamatsu is a Michael Smith Foundation for Health
Research Senior Graduate trainee and a Natural Sciences and
Engineering Research Council of Canada Doctoral trainee.
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