Journal of Rehabilitation Medicine 51-7 | Page 4

J Rehabil Med 2019; 51: 473–478
REVIEW ARTICLE
EFFECT OF DIFFERENT LEVELS OF EXERCISE ON TELOMERE LENGTH: A
SYSTEMATIC REVIEW AND META-ANALYSIS
Xiufang LIN, MD, Jianghua ZHOU, MD and Birong DONG, MD
From The Center of Gerontology andGeriatrics/National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University,
Chengdu, China
Objective: To investigate the effect of different le-
vels of exercise on telomere length.
Methods: CINAHL, SPORTDiscus (EBSCO), OVID
(Medline) and EMBASE databases were searched for
eligible studies. Methodological quality was evalua-
ted using the Newcastle-Ottawa Scale, and hetero-
geneity among the studies was assessed using the
I-squared test. When heterogeneity among studies
was high (I 2  > 50%), a random-effects model was
used (Review Manager version 5, Cochrane Collabo-
ration, Copenhagen, Denmark); otherwise, a fixed-
effects model was used.
Results: Eleven eligible studies involving 19,292 par-
ticipants were included in this meta-analysis. Long-
er telomere length was associated with physically
active individuals, with a mean difference (MD) of
0.15 (95% confidence interval; 95% CI 0.05, 0.24);
I 2  = 99%. Longer telomere length was significantly
associated with robust exercise (MD 0.08 (95% CI
0.04, 0.12)); I 2  = 99%, as was moderate exercise (MD
0.07 (95% CI 0.03, 0.11)); I 2  = 100%. Subgroup ana-
lysis revealed that longer telomere length was positi-
vely associated with exercise, regardless of sex, but
was not statistically significant in elderly populations.
Conclusion: Compared with inactive individuals,
telomere lengths were longer in active subjects, re-
gardless of the intensity of exercise.
Key words: exercise; telomere length; meta-analysis.
Accepted Apr 25, 2019; Epub ahead of print May 16, 2019
J Rehabil Med 2019; 51: 473–478
Correspondence address: Birong Dong, The Center of Gerontology and
Geriatrics/National Clinical Research Center for Geriatrics, West China
Hospital, Sichuan University, Chengdu, China. E-mail: zjhwthx@163.
com
T
elomeres are special structures located at the end of
human eukaryotic chromosomes that help maintain
chromosomal stability and integrity (1, 2). Telomerase
is a critical ribonucleoprotein enzyme that synthesizes
G-rich repeats to maintain telomere length (3), but
is suppressed in most mammalian somatic cells. As
a result, 25–200 base-pair pieces are removed from
chromosomal termini with each round of cell division
(4). Therefore, many studies investigating ageing re-
gard telomere length as an important biomarker. In ad-
dition, many age-related diseases, including diabetes,
dementia and chronic psychiatric disorders, have been
found to be significantly associated with shortened
telomere length (5–7).
LAY ABSTRACT
Telomeres are structures found at the end of human
chromosomes that help to protect the chromosome.
Telomeres become shorter with ageing and age-related
diseases. This study investigated the effect of different
levels of exercise on telomere length. Research databa-
ses were searched for relevant studies and these were
checked for eligibility. Studies included in this meta-
analysis were analysed for heterogeneity, using the ran-
dom-effects or fixed-effects models. Longer telomere
length was found to be associated with physically ac-
tive individuals, and significantly associated with robust
and moderate exercise. Subgroup analysis revealed
that longer telomere length was positively associated
with exercise, regardless of the person’s sex, but this
was not statistically significant in elderly populations. In
conclusion, compared with inactive individuals, people
who were active had longer telomere lengths, regard-
less of the intensity of exercise.
Exercise has been shown to decrease the incidence of
morbidity and mortality in individuals with age-related
diseases (8, 9). For example, aerobic exercise contri-
butes to higher aerobic cardiovascular fitness, which is
closely related to good health and lengthened telomeres
(10). In addition, resistance exercise and yoga have
been found to have a positive effect on survival and
telomere length (11). The proposed potential mecha-
nisms include reduced oxidative stress and reduced
systemic inflammation (12, 13). However, the results
of existing studies investigating whether telomeres are
longer in active individuals are contradictory. Some
studies have reported that physical activity is not
associated with longer telomeres in leukocytes and
muscle cells (13–15).
The current study therefore aimed to evaluate the
effect of different intensities and types of exercise on
telomere length through a literature search and meta-
analysis.
METHODS
Search strategy
This study was performed according to the Meta-analyses of
Observational Studies in Epidemiology (MOOSE) checklist.
CINAHL, SPORTDiscus (EBSCO), OVID (Medline) and EM-
BASE databases were searched to retrieve potentially eligible
studies in April 2017; the search was updated in November 2017.
This is an open access article under the CC BY-NC license. www.medicaljournals.se/jrm
Journal Compilation © 2019 Foundation of Rehabilitation Information. ISSN 1650-1977
doi: 10.2340/16501977-2560