The relationships between active transport to work or school and cardiovascular health or body...

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published online 9 April 2013Asia Pac J Public HealthHuilan Xu, Li Ming Wen and Chris Rissel

Health or Body Weight : A Systematic ReviewThe Relationships Between Active Transport to Work or School and Cardiovascular

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Review

The Relationships Between Active Transport to Work or School and Cardiovascular Health or Body Weight: A Systematic Review

Huilan Xu, MBiostat, MPH1, Li Ming Wen, MD, MMed, PhD1,2 and Chris Rissel, MPH, PhD2

AbstractTo systematically examine the relationships between active transport to work or school and cardiovascular health, body weight, or other health outcomes, a systematic review of the literature was conducted in September 2012 using 3 electronic databases. A total of 3887 articles were screened, 30 full text articles were retrieved, and 19 articles were identified. Two reviewers independently assessed the quality of each article. The review found that active transport to work or school was significantly associated with improved cardiovascular health and lower body weight. However, the strength of the evidence varied from weak (mental health and cancer), moderate (body weight), to strong (cardiovascular health). The evidence was limited by lack of comparability of study outcomes, weak study designs, small sample sizes, and lack of experimental studies. Further research is needed to examine the effect of active transport on health using stronger research designs, including randomized controlled trials or longitudinal studies.

Keywordsepidemiology, public health, population health, evaluation, education, health promotion, air pollution and health, occupational and environmental health

Introduction

Active transport (walking, cycling, and public transport) is one component of an active lifestyle, which can be incorporated into routine daily activities.1,2 There is emerging and consistent evi-dence that active transport increases physical activity.3-7 Increased physical activity reduces mor-bidity and mortality rates from cardiovascular disease (CVD), hypertension, obesity, diabetes, respiratory disease, certain cancers, and musculoskeletal and mental health problems.8-11 Yet the evidence linking active transport directly to health outcomes has not been examined extensively, and the relationship between active transport and health remains unclear.

1Health Promotion Service, South Western Sydney & Sydney Local Health Districts, NSW Health, Australia2University of Sydney, Australia

Corresponding Author:Li Ming Wen, Health Promotion Service, South Western Sydney & Sydney Local Health Districts, Level 9, King George V Building, Missenden Road, Camperdown NSW 2050, Australia. Email: [email protected]

482965 APHXXX10.1177/1010539513482965Asia-Pacific Journal of Public HealthXu et alresearch-article2013



2 Asia-Pacific Journal of Public Health XX(X)

We found 6 reviews that examined the health benefits of active transport,3,4,12-15 which included body weight, cardiovascular health, and all-cause mortality, for adults or school children. The reviews found that the cross-sectional nature of many studies of this kind prevented detection of a causal relationship between active transport and health outcomes.3,4,12,13,15 Lack of standardized definitions and measurements of active transport were identified by the reviews,3,4,12-14 and the use of nonobjective health outcome measures (eg, self-reported body weight) was also of con-cern.4,13 Other potential health outcomes such as cancer and mental health were not covered in the previous reviews.

To date, there have been no systematic reviews of the literature examining the impact of active transport to work or school (excluding trips for other reasons, eg, social and entertainment) on health outcomes for both adults and school children. The purpose of this review was to systemati-cally examine the relationships between active transport to work or school and body weight, cardiovascular health, and other health outcomes, including cancer, mental health, and injury, and also to update the existing evidence about health benefits of active transport for adults and school children. This review focused on the research literature from January 2002 to September 2012 because several previous reviews have already reviewed the active transport research litera-ture published before 2002.

Methods

Search Strategy

A literature search was conducted using the electronic databases (January 2002-September 2012), including MEDLINE, the Cochrane Central Register of Controlled Trials (CENTRAL), and Cochrane Database for Systematic Review. The studies were limited to those written in English. Included study designs were limited to randomized controlled trials (RCTs), cohort, case-control, and cross-sectional studies, and systematic reviews. Study participants were limited to school children and adults in the workforce. Active transport was defined as walking, cycling, or taking public transport to school or work and the health outcomes included body weight, cardiovascular health, cancer, mental health, injury, and general health. The search strategy used for the MEDLINE database is displayed in Table 1. A similar search strategy was used for CENTRAL and the Cochrane database. Additional manual searching was conducted for referenced articles of those published articles included in this review. Grey literature, such as unpublished studies and ongoing trials, was not included.

Study Selection

The present systematic review focused on the association between active transport (walking, cycling, and public transportation) to work or school and health outcomes. To be selected for this present review, studies had to meet 2 inclusion criteria: the study had to (1) investigate quantita-tive associations between active transport (walking/cycling/public transport) to work or school and health outcomes (excluding physical activity) and (2) be published in English with full text in a peer-reviewed journal.

The following types of studies were excluded: (1) validation studies, (2) pilot studies, (3) stud-ies investigating associations between walking or cycling and physical activity, and (4) studies investigating association between active transport and environmental health.

A total of 3887 articles were identified through database searching; 220 duplicated articles were removed, and 3635 articles were excluded by title. References of the remaining 32 articles were searched manually to identify relevance of the articles, and 16 additional articles were included. Of these 48 articles, 18 articles were excluded based on their abstracts. The remaining



Xu et al 3

Table 1. The Search Strategy Used for Medline Database (January 2002 to September 2012).a

Database: Ovid MEDLINE(R) <1946 to September Week 3 2012>Search Strategy: 1. randomized controlled trial.tw,sh,pt. (342294) 2. randomized.ab. (240228) 3. randomly.ab. (172607) 4. cross-section*.ab. (139212) 5. cohort.ab. (179276) 6. case-control.ab. (57800) 7. systematic review.ab. (19866) 8. 1 or 2 or 3 or 4 or 5 or 6 or 7 (872264) 9. walk*.mp. (63087)10. public transport*.mp. (640)11. cycl*.mp. (894515)12. active travel*.mp. (75)13. active transport*.mp. (14152)14. active commut*.mp. (139)15. non-motori*ed.mp. (66)16. bik*.mp. (2376)17. bicycl*.mp. (26936)18. bus.mp. (1758)19. train.mp. (16175)20. 9 or 10 or 11 or 12 or 13 or 14 or 15 or 16 or 17 or 18 or 19 (1002675)21. overweight.mp. (30399)22. body weight.mp. (245450)23. obes*.mp. (175612)24. BMI.mp. (55483)25. body mass index.mp. (109948)26. heart disease*.mp. (165311)27. Cardiovascular disease*.mp. (134777)28. mental health.mp. (94583)29. injur*.mp. (677752)30. health.mp. (1652490)31. cancer.mp. (873684)32. 21 or 22 or 23 or 24 or 25 or 26 or 27 or 28 or 29 or 30 or 31 (3638739)33. adult*.mp. (4116056)34. school child*.mp. (15414)35. adolescent.mp. (1509723)36. teenager.mp. (1442)37. 33 or 34 or 35 or 36 (4568006)38. 8 and 20 and 32 and 37 (10785)39. limit 38 to (english language and humans and yr=“2002 -Current”) (6995)40. (39 not workplace injury not sport injury not biological transport not biological travel not substrate

cycling not therapy not physiology not exercise test not validation study not clinic* not built environment* not chromosome walking not Dandy-Walker Syndrome not treadmill not gait not cell).mp. (2188)

41. remove duplicates from 40 (2062)

aThe asterisk sign stands for any character(s).




30 full texts were assessed for their eligibility, and a further 11 articles that did not meet the inclu-sion criteria were excluded. Finally, 19 articles (13 individual articles and 6 reviews, including 76 studies) were included in the present systematic review. The process of study selection is reported in Figure 1. Because of the heterogeneity of the studies, it was not possible to conduct a meta-analysis. Therefore, the results are presented descriptively.

Assessment of Included Articles

Two reviewers (HX and LMW) independently screened the study titles and abstracts and then critically appraised the selected articles. Scores for each article were given using a previously used assessment tool13 (Table 2) as a quality index. Brief summaries of all the studies included in this review are presented in Tables 3, 4, and 5.

Results

Description of Studies

The present systematic review included 4 previous systematic reviews, 2 narrative reviews, and 13 articles derived from 12 individual studies (1 study published 2 articles investigating the asso-ciation between cycling to school and cardiovascular health and body weight separately).

Figure 1. Study selection process.



Xu et al 5

Of the 13 articles, 4 reported the association between active transport to school with body weight,16-19 1 study reported the association between active transport and both body weight and physical fitness,20 5 articles reported the association between active transport and cardiovascular health,21-25 1 article reported the association between active transport and both cardiovascular health and body weight,26 and 2 other articles reported the association with colon cancer, quality of life, and mental health respectively.27,28

Among the articles included in the previous 6 reviews, 63 studies reported the association between active travel and body weight,3,4,12,13 10 studies reported the association with cardiovas-cular health,14,15 and 3 studies reported the association with all-cause mortality.15

Therefore, the present systematic review included 88 individual studies investigating the asso-ciations between active transport to work or school and cardiovascular health, body weight, and other health outcomes.

Quality of Studies

Of 6 review articles, 4 reviews did not assess the quality of selected studies; 1 did quality assessment but did not report it, and only 1 review had developed and applied an assessment

Table 2. Quality Criteria and Specification of Scores.a

Quality Criteria Specification of Scores Score

1. Study type Cross-sectional/Case-control 0Longitudinal/RCT/Quasiexperiment 1

2. Assessment of exposure (active transport)

Walking and cycling combined, dichotomous 0Walking and cycling combined, categorical 1Walking and cycling combined, continuous 2Walking and cycling separate, dichotomous 1Walking and cycling separate, categorical 2Walking and cycling separate, continuous 3

3a. Assessment of CV health or physical fitness or other health outcomes

Self-reported, not validated 0Self-reported, validatedb 1Objectively measured,c not validated 1Objectively measured, validated 2

3b. Assessment of body weight as outcome

Self-reported 0Objectively measuredd 2

4. Sample size Too small for meaningful results (<500) 0500 to 10 000 1>10 000 2

5. Completeness of data Data available for <80% of participants or not reported

0

Data available for >80% of participants 16. Control for confounding Not controlled for confounders 0

Controlled at least for gender, age, and some proxy of SES (eg, income and education)

1

Total score Minimum 0 Maximum 10

Abbreviations: RCT, randomized controlled trial; CV, cardiovascular; SES, socioeconomic status.aAdapted from Wanner et al.13

bValidity of the instrument was examined against another measure of health outcome.cAn objective measure of health outcome was used, such as muscle endurance and functional strength.dHeight and weight were measured objectively.



6

Tab

le 3

. A

ssoc

iatio

ns B

etw

een

Act

ive

Tra

nspo

rt t

o Sc

hool

or

Wor

k an

d Bo

dy W

eigh

t.

Aut

hor

(Dat

e)/Q

ualit

y Sc

ore

Stud

y D

esig

nSa

mpl

eA

ge (

year

s)A

ctiv

e T

rave

l C

lass

ifica

tion

Hea

lth O

utco

me

Indi

cato

rsA

djus

ted

Con

foun

ders

Mai

n Fi

ndin

gs

Ara

ngo

et a

l16

(201

1)/5

Cro

ss-

sect

iona

l54

6 C

hild

ren,

M

onte

ria,

C

olom

bia

14.8

(m

ean)

Act

ive

(wal

king

/cy

clin

g)/in

activ

e (c

ar/b

us/

mot

orcy

cle/

othe

r)

to s

choo

l

BMI

Age

, gen

der,

sch

ool

loca

tion,

PA

leve

l, sc

reen

tim

e

Chi

ldre

n w

ho a

ctiv

e tr

avel

ed t

o sc

hool

had

a lo

wer

lik

elih

ood

of b

eing

ove

rwei

ght

com

pare

d w

ith t

hose

w

ho in

activ

e tr

avel

ed t

o sc

hool

(A

OR

= 0

.5; 9

5% C

I =

0.3

-0.8

)

Men

doza

et

al17

(20

11)/

7C

ross

-se

ctio

nal

789 Ado

lesc

ents

, U

nite

d St

ates

14.4

(m

ean)

Wal

king

/cyc

ling

to

scho

ol, m

in/d

BMI z

-sco

re, w

aist

ci

rcum

fere

nce,

sk

in fo

lds

Die

tary

ene

rgy

inta

ke,

soci

oeco

nom

ic

and

dem

ogra

phic

ch

arac

teri

stic

s

Gre

ater

min

utes

of a

ctiv

e co

mm

utin

g w

ere

asso

ciat

ed w

ith lo

wer

BM

I z-s

core

and

ski

n fo

lds

(β =

−0.

07, P

= .0

46; β

= −

0.06

. P =

.29)

; gre

ater

be

fore

- an

d af

ter-

scho

ol M

VPA

exp

lain

ed p

art

of

the

rela

tions

hip

betw

een

activ

e co

mm

utin

g an

d w

aist

cir

cum

fere

nce

(Sob

el z

= −

1.98

; P =

.48)

Paba

yo e

t al

18

(201

0)/5

Long

itudi

nal

1170

Chi

ldre

n,

Que

bec,

C

anad

a

Base

line

age:

6;

follo

w-

up: 8

Act

ive(

wal

king

/cy

clin

g)/

inac

tive(

bus/

publ

ic

tran

sit/

car)

to

scho

ol

BMI z

-sco

res

Soci

oeco

nom

ic

and

dem

ogra

phic

ch

arac

teri

stic

s; m

othe

r’s

over

wei

ght/

obes

e st

atus

; m

othe

r’s

perc

eptio

n of

chi

ld’s

hea

lth a

nd

neig

hbor

hood

qua

lity

Act

ive

trav

el t

o an

d fr

om s

choo

l bot

h w

hen

in

kind

erga

rten

and

in g

rade

1 w

as p

redi

ctiv

e of

a

low

er B

MI z

-sco

re (β

= −

0.18

; P =

.05)

in g

rade

1;

act

ive

trav

el t

o an

d fr

om s

choo

l bot

h w

hen

in

kind

erga

rten

, gra

de 1

, and

gra

de 2

was

pre

dict

ive

of

a lo

wer

BM

I z-s

core

(β

= −

0.30

; P =

.003

) in

gra

de 2

Wen

et

al19

(2

010)

/4C

ross

-se

ctio

nal

1362

Chi

ldre

n,

Sydn

ey,

Aus

tral

ia

10-1

2 (r

ange

)W

alki

ng/c

ar/

publ

ic t

rans

port

/co

mbi

ned

to

scho

ol

BMI

Scre

en t

ime

Com

pare

d w

ith c

hild

ren

who

wer

e dr

iven

to

scho

ol

daily

, chi

ldre

n w

ho w

alke

d to

sch

ool d

aily

wer

e si

gnifi

cant

ly le

ss li

kely

to

be o

bese

(A

OR

= 0

.20;

95

% C

I = 0

.16-

0.74

)A

nder

sen

et

al20

(20

09)/

8C

ross

-se

ctio

nal

1249

A

dole

scen

ts,

Den

mar

k

15-1

9 (r

ange

)C

yclin

g/w

alki

ng/

trai

n or

bus

/car

or

mot

orcy

cle

to

scho

ol

BMI,

phys

ical

fit

ness

: aer

obic

po

wer

; mus

cle

endu

ranc

e;

func

tiona

l st

reng

th;

flexi

bilit

y; a

gilit

y

Gen

der

No

diffe

renc

e fo

und

in B

MI a

mon

g ad

oles

cent

s us

ing

diffe

rent

mod

els

to t

rave

l to

scho

ol; c

hild

ren

who

bic

ycle

d to

sch

ool h

ad h

ighe

r ae

robi

c po

wer

(d

iffer

ence

= 2

.34;

95%

CI =

1.4

5-3.

24),

mus

cle

endu

ranc

e (d

iffer

ence

in s

it-up

s =

2.9

7, 9

5% C

I =

0.84

-5.0

9; d

iffer

ence

in s

tatic

bac

k st

reng

th =

17.

63,

85%

CI =

9.0

3-26

.22)

, and

flex

ibili

ty (

diffe

renc

e =

3.

14; 9

5% C

I = 1

.72-

4.57

) th

an c

hild

ren

who

wal

ked

or w

ere

driv

en t

o sc

hool

(con

tinue

d)



7

Aut

hor

(Dat

e)/Q

ualit

y Sc

ore

Stud

y D

esig

nSa

mpl

eA

ge (

year

s)A

ctiv

e T

rave

l C

lass

ifica

tion

Hea

lth O

utco

me

Indi

cato

rsA

djus

ted

Con

foun

ders

Mai

n Fi

ndin

gs

Faul

kner

et

al

(200

9)Sy

stem

atic

re

view

10 S

tudi

es

(9 o

ut 1

0 ar

e cr

oss-

sect

iona

l st

udie

s)

Scho

ol

child

ren

4 St

udie

s: u

sual

tr

avel

to/

from

sc

hool

(ca

r/cy

cle/

bus/

wal

k);

2 st

udie

s: u

sual

m

ode

of t

rans

port

9 St

udie

s:

body

wei

ght/

BMI;

1 st

udy:

pe

rcen

tage

bod

y fa

t

Not

rep

orte

dO

nly

1 st

udy

repo

rted

act

ive

com

mut

ers

havi

ng a

lo

wer

bod

y w

eigh

t; 9

stud

ies

foun

d no

diff

eren

ce

in b

ody

wei

ght/

BMI b

etw

een

activ

e an

d pa

ssiv

e co

mm

uter

s

Lee

et a

l4 (2

008)

Syst

emat

ic

revi

ew18

Stu

dies

(16

ou

t of

18

wer

e cr

oss-

sect

iona

l st

udie

s)

Scho

ol

child

ren

Act

ive

com

mut

ing:

w

alki

ng/c

yclin

g to

sc

hool

15 S

tudi

es: B

MI;

2 st

udie

s:

over

wei

ght/

obes

ity; 1

stu

dy:

perc

enta

ge b

ody

fat

Not

rep

orte

dO

nly

3 st

udie

s fo

und

a co

nsis

tent

ass

ocia

tion

betw

een

activ

e co

mm

utin

g an

d lo

wer

bod

y w

eigh

t; 5

stud

ies

foun

d si

gnifi

cant

res

ults

onl

y fo

r su

bgro

ups

of t

he s

tudy

pop

ulat

ion;

9 s

tudi

es fo

und

no s

igni

fican

t as

soci

atio

n; 1

stu

dy fo

und

a si

gnifi

cant

as

soci

atio

n be

twee

n ac

tive

com

mut

ing

and

high

er

BMI

Dav

ison

et

al12

(2

008)

Nar

rativ

e re

view

5 St

udie

s (4

ou

t of

5

wer

e cr

oss-

sect

iona

l st

udie

s)

Scho

ol

child

ren

Act

ive

com

mut

ing:

w

alki

ng/c

yclin

g to

sc

hool

BMI

Not

rep

orte

dO

nly

1 st

udy

foun

d m

iddl

e-sc

hool

-age

d yo

uth

who

w

ere

at r

isk

for

over

wei

ght

wer

e le

ss li

kely

tha

n th

ose

who

wer

e no

nove

rwei

ght

to w

alk

or c

ycle

to

sch

ool;

3 st

udie

s fo

und

no a

ssoc

iatio

n be

twee

n ac

tive

com

mut

ing

to s

choo

l and

BM

I; 1

stud

y fo

und

BMI o

f act

ive

com

mut

ers

incr

ease

d m

ore

duri

ng a

5-

mon

th p

erio

d th

an d

id B

MI o

f ina

ctiv

e co

mm

uter

sW

anne

r et

al13

(2

012)

Syst

emat

ic

revi

ew30

Stu

dies

(29

ou

t of

30

wer

e cr

oss-

sect

iona

l st

udie

s)

Adu

ltsW

alki

ng o

nly;

cy

clin

g on

ly; b

oth

wal

king

and

cyc

ling

Ove

rwei

ght/

obes

ity b

ased

on

BM

I

In a

ll, 2

5 st

udie

s ad

just

ed

conf

ound

ers

Inve

rse

asso

ciat

ion

betw

een

activ

e tr

ansp

ort

and

body

wei

ght

foun

d in

25

stud

ies;

3 s

tudi

es fo

und

no

asso

ciat

ion;

2 s

tudi

es fo

und

a po

sitiv

e as

soci

atio

n

Abb

revi

atio

ns: B

MI,

body

mas

s in

dex;

PA

, phy

sica

l act

ivity

; AO

R, a

djus

ted

odds

rat

io; C

I, co

nfid

ence

inte

rval

; MV

PA, m

oder

ate-

to-v

igor

ous

phys

ical

act

ivity

.

Tab

le 3

. (co

ntin

ued)



8

Tab

le 4

. A

ssoc

iatio

ns B

etw

een

Act

ive

Tra

nspo

rt t

o W

ork

or S

choo

l and

Car

diov

ascu

lar

Hea

lth.

Aut

hor

(dat

e) /

Qua

lity

Scor

eSt

udy

Des

ign

Inte

rven

tion

Sam

ple

Age

(ye

ars)

AT

Cla

ssifi

catio

nH

ealth

Out

com

e In

dica

tors

Adj

uste

d C

onfo

unde

rsM

ain

Find

ings

And

erse

n et

al21

(2

011)

/6

Long

itudi

nal

No

334

Chi

ldre

n,

Ode

nse,

D

enm

ark

9.7

(mea

n)U

sual

tra

vel t

o sc

hool

(ca

r or

mot

orcy

cle/

bus

or

trai

n/bi

cycl

e/fo

ot)

CR

F; C

VD

ris

ks (

sum

of

z-sc

ores

for

sum

of s

kin

fold

s, s

ysto

lic B

P, T

C/

HD

L ra

tio, T

G, H

OM

A

and

reve

rse

of fi

tnes

s)

Gen

der

Base

line

in fi

tnes

s: c

ycle

> n

oncy

cle,

3

mL/

m−

1 /kg

−1

Follo

w-u

p: c

ycle

> n

oncy

cle

in fi

tnes

s,

2.5

mL/

m−

1 /kg

−1 ;

cycl

e <

non

cycl

e in

su

m o

f z-s

core

s, 1

.58

de G

eus

et a

l22

(200

8)/6

Qua

siex

peri

men

tal

stud

y1-

Year

cyc

ling

to

wor

k fo

r 2

to

15 k

m, a

t lea

st

3 tim

es/w

k

IG: 6

5; C

G:

15; F

land

ers,

Be

lgiu

m

IG: 4

3; C

G: 4

9 (m

ean)

Cyc

ling

to w

ork

Cor

onar

y ri

sk fa

ctor

s;

men

tal h

ealth

; qua

lity

of li

fe

Age

The

incr

ease

s in

Wm

ax, W

max

/kg,

V

O2p

eak

and

VO

2pea

k/kg

ove

r tim

e w

ere

sign

ifica

ntly

hig

her

in t

he IG

tha

n in

the

CG

Bo

uts/

wk,

exp

ende

d en

ergy

(kc

al/w

k)

wer

e si

gnifi

cant

ly h

ighe

r in

the

IG t

han

in t

he C

G

TC

, LD

L, T

C/H

DL,

and

DBP

dec

reas

ed

and

HD

L in

crea

sed

sign

ifica

ntly

in t

he

IG b

ut n

ot s

igni

fican

tly d

iffer

ent

from

th

e C

G

The

incr

easi

ng o

f vita

lity

in t

he IG

was

si

gnifi

cant

ly h

ighe

r th

an t

hat

in t

he C

G

Phys

ical

func

tioni

ng in

crea

sed

sign

ifica

ntly

ove

r tim

e in

the

wom

en

IGG

uo e

t al

23

(200

9)/7

Cro

ss-s

ectio

nal

No

1024

Adu

lts;

Beiji

ng, C

hina

75%

, 18-

49;

25%

age

d >

49.

Wal

king

/cyc

ling/

bus/

car

or t

axi

Dys

lipid

emia

(T

C, T

G)

Gen

der,

age

, ed

ucat

ion,

sm

okin

g,

drin

king

, edi

ble

oil i

ntak

e, s

alt

inta

ke, B

MI

Peop

le d

rivi

ng a

car

or

taki

ng a

tax

i and

ta

king

the

bus

to

wor

k ha

d hi

gher

pr

obab

ility

of d

yslip

idem

ia t

han

thos

e w

alki

ng t

o w

ork

(AO

R =

2.2

1, 9

5% C

I =

1.2

8-3.

84; A

OR

= 1

.99.

95%

CI =

1.

33-2

.97)

N

o di

ffere

nce

betw

een

cycl

ing

and

wal

king

Mol

ler

et a

l24

(201

1)/5

RC

T8-

Wee

k co

mm

uter

cy

clin

g

48 A

dults

; Isl

and

of F

unen

, D

enm

ark

IG: 4

4.4;

CG

: 46

(m

ean)

Min

imum

of 2

0 m

inut

es o

f da

ily c

omm

uter

cyc

ling

VO

2max

, CR

F, s

um

of s

kin

fold

s, D

BP,

sy

stol

ic B

P

Gen

der,

age

, ba

selin

e m

easu

reIn

terv

entio

n >

con

trol

in V

O2m

ax: 2

06

mL

O2/

min

Inte

rven

tion

> c

ontr

ol in

CR

F: 2

.6 m

L O

2/kg

/min

In

terv

entio

n <

con

trol

in s

um o

f ski

n fo

lds:

12.

1 m

m

(con

tinue

d)



9

Aut

hor

(dat

e) /

Qua

lity

Scor

eSt

udy

Des

ign

Inte

rven

tion

Sam

ple

Age

(ye

ars)

AT

Cla

ssifi

catio

nH

ealth

Out

com

e In

dica

tors

Adj

uste

d C

onfo

unde

rsM

ain

Find

ings

N

o di

ffere

nce

betw

een

inte

rven

tion

and

cont

rol g

roup

s in

DBP

and

sys

tolic

BP

Wen

nber

g et

al25

(2

010)

/6C

ase-

cont

rol

No

Cas

e: 2

04;

cont

rol:

327;

V

aste

rbot

ten,

Sw

eden

Cas

e:51

.4;

cont

rol:

50.6

(m

ean)

Tra

vel t

o w

ork

(wal

king

, cy

clin

g, o

r bu

s ev

ery

seas

on/c

ar e

very

sea

son/

car

1 to

3 s

easo

ns)

Inci

denc

e of

MI

Smok

ing,

ed

ucat

ion,

hy

pert

ensi

on,

diab

etes

, le

isur

e tim

e PA

, oc

cupa

tiona

l PA

Adj

uste

d O

R fo

r ca

r co

mm

uter

s is

1.7

7 (9

5% C

I = 1

.05-

2.99

)T

he O

R fo

r ca

r co

mm

uter

s fr

om

med

iatio

n an

alys

is is

1.4

0 (9

5% C

I =

0.76

-2.5

7), 4

0.1%

of M

I ris

k re

late

d to

co

mm

utin

g ac

tivity

can

be

expl

aine

d by

all

risk

fact

ors

and

infla

mm

ator

y an

d he

mos

tatic

mar

kers

Hu

et a

l26

(200

2)/6

Cro

ss-s

ectio

nal

No

3976

; Tia

njin

g,

Chi

na39

.9 (

mea

n);

15-6

9 (r

ange

)

Usu

al t

rave

l to

scho

ol o

r w

ork

(0 m

inut

es: b

us o

r no

com

mut

ing;

phy

sica

l ac

tivity

, 1-3

0 m

inut

es: f

oot

or b

icyc

le, 3

1-60

min

utes

: fo

ot o

r bi

cycl

e, >

60

min

utes

: bic

ycle

)

CV

D r

isk

fact

ors:

bod

y m

ass

inde

x; D

BP;

syst

olic

BP

Age

, edu

catio

n,

smok

ing,

al

coho

l, BM

I, oc

cupa

tiona

l PA

The

like

lihoo

d of

hyp

erte

nsio

n in

crea

sed

alon

g w

ith t

he t

ime

on w

alki

ng o

r cy

clin

g to

wor

k or

sch

ool i

n bo

th

gend

ers

(tre

nd t

est,

P <

.05)

Dai

ly t

ime

on a

ctiv

e co

mm

utin

g w

as

inve

rsel

y re

late

d to

mea

n BM

I and

pr

eval

ence

of o

verw

eigh

t am

ong

men

Ham

er a

nd

Chi

da14

(20

08)

Met

a-an

alyt

ic r

evie

wN

o8

Stud

ies

(7

pros

pect

ive

coho

rt s

tudy

, 1

case

-con

trol

st

udy)

Adu

lts (

6 st

udie

s co

ntai

ned

both

men

an

d w

omen

, 2

stud

ies

wer

e m

en

only

)

5 St

udie

s: t

ime

spen

t w

alki

ng/c

yclin

g to

wor

k; 1

st

udy:

tim

e sp

ent

wal

king

to

wor

k; 1

stu

dy: w

alki

ng/

cycl

ing

to w

ork;

1 s

tudy

: w

alki

ng/c

yclin

g/bu

s/ca

r to

wor

k.

2 St

udie

s: C

HD

; 2

stud

ies:

hyp

erte

nsio

n; 1

st

udy:

CV

D m

orta

lity;

1

stud

y: s

trok

e; 1

stu

dy:

diab

etes

.

All

stud

ies

adju

sted

co

nfou

nder

sT

he o

vera

ll ri

sk r

atio

was

0.8

9 w

ith 9

5%

CI =

0.8

1-0.

98; P

= .0

16T

he p

rote

ctiv

e ef

fect

s of

act

ive

com

mut

ing

wer

e m

ore

robu

st a

mon

g w

omen

(ri

sk r

atio

= 0

.87;

95%

CI =

0.

77-0

.98;

P =

.02)

For

men

, ris

k ra

tio =

0.9

1; 9

5% C

I =

0.79

-1.0

4; P

= .1

65 Sh

epha

rd15

(2

008)

Nar

rativ

e re

view

No

2 St

udie

s1

Stud

y:

adul

ts; 1

st

udy:

sch

ool

child

ren

1 St

udy:

cyc

ling

to w

ork;

1

stud

y: c

yclin

g to

sch

ool

Inci

denc

e of

MI;

CR

FN

ot r

epor

ted

The

inci

denc

e of

MI a

mon

g th

ose

cycl

ing

to w

ork

was

onl

y ha

lf of

tha

t in

the

ge

nera

l pop

ulat

ion

Chi

ldre

n w

ho c

ycle

d to

sch

ool w

ere

subs

tant

ially

mor

e fit

tha

n th

ose

who

w

alke

d or

wer

e dr

iven

to

scho

ol

Abb

revi

atio

ns: A

T, a

ctiv

e tr

ansp

ort;

TC

, tot

al c

hole

ster

ol; I

G, i

nter

vent

ion

grou

p; L

DL,

low

-den

sity

lipo

prot

ein;

MI,

myo

card

ial i

nfar

ctio

n; C

RF,

car

dior

espi

rato

ry fi

tnes

s; H

DL,

hig

h-de

nsity

lipo

prot

ein;

CG

, co

ntro

l gro

up; D

BP, d

iast

olic

blo

od p

ress

ure;

CH

D, c

oron

ary

hear

t di

seas

e; C

VD

, car

diov

ascu

lar

dise

ase;

TG

, tri

glyc

erid

es; W

max

, max

imal

ext

erna

l pow

er A

OR

, adj

uste

d od

ds r

atio

; BP,

blo

od p

ress

ure;

H

OM

A, h

omeo

stat

ic m

odel

ass

essm

ent;

VO

2pea

k, h

ighe

st o

xyge

n up

take

; PA

, phy

sica

l act

ivity

.

Tab

le 4

. (co

ntin

ued)



10

Tab

le 5

. A

ssoc

iatio

n Be

twee

n A

ctiv

e T

rans

port

to

Wor

k an

d H

ealth

Out

com

es.

Aut

hor

(dat

e) /

Qua

lity

Scor

eSt

udy

Des

ign

Sam

ple

Age

(ye

ars)

Act

ive

Tra

vel/

Com

mut

ing

PA

Cla

ssifi

catio

nH

ealth

Out

com

e In

dica

tors

Adj

uste

d C

onfo

unde

rsM

ain

Find

ings

Han

sson

et

al27

(2

011)

/6C

ross

-se

ctio

nal

21 0

88 A

dults

; Sc

ania

, Sw

eden

45 (

med

ian)

Wal

king

/cyc

ling

<30

m

inut

es; c

ar <

30

min

utes

/30-

60

min

utes

/>60

m

inut

es; b

us/t

rain

<

30 m

inut

es/3

0-60

m

inut

es/>

60 m

inut

es.

Perc

eive

d sl

eep

qual

ity,

ever

yday

str

ess,

men

tal

heal

th, s

elf-r

ated

he

alth

, vita

lity,

sic

knes

s/ab

senc

e

Gen

der,

age

, edu

catio

n,

plac

e of

bir

th,

occu

patio

nal c

lass

, job

st

rain

, ove

rtim

e, h

isto

ry

of u

nem

ploy

men

t, in

com

e, fi

nanc

ial s

tres

s,

resi

dent

ial l

ocat

ion,

fa

mily

situ

atio

n

Com

pare

d w

ith a

ctiv

e co

mm

uter

s, c

ar

com

mut

ers

in t

he 3

0- t

o 60

-min

ute

cate

gory

an

d pu

blic

tra

nspo

rt c

omm

uter

s in

the

>

60-m

inut

e ca

tego

ry w

ere

mor

e lik

ely

to

expe

rien

ce p

erce

ived

poo

r sl

eep

qual

ity

(AO

R =

1.3

7, 9

5% C

I = 1

.16-

1.62

; AO

R =

1.

41, 9

5% C

I = 1

.08-

1.85

)C

ar c

omm

uter

s in

the

30-

to

60-m

inut

e ca

tego

ry w

ere

mor

e lik

ely

to e

xper

ienc

e ev

eryd

ay s

tres

s (A

OR

= 1

.37;

95%

CI =

1.1

6-1.

62),

whe

reas

pub

lic t

rans

port

com

mut

ers

in t

he <

30-m

inut

e ca

tego

ry w

ere

less

like

ly

to e

xper

ienc

e ev

eryd

ay s

tres

s

C

ar c

omm

uter

s in

the

<30

and

30-

to

60-m

inut

e ca

tego

ries

and

pub

lic t

rans

port

co

mm

uter

s in

the

>60

-min

ute

cate

gory

wer

e m

ore

likel

y to

hav

e lo

w s

elf-r

ated

hea

lth

(AO

R =

1.1

2, 9

5% C

I = 1

.02-

1.23

; AO

R =

1.

25, 9

5% C

I = 1

.09-

1.43

; AO

R =

1.4

4, 9

5%

CI =

1.1

6-1.

80)

C

ar c

omm

uter

s in

the

<30

and

30-

to

60-m

inut

e ca

tego

ries

and

pub

lic t

rans

port

co

mm

uter

s in

30-

60 a

nd >

60 m

inut

e ca

tego

ries

wer

e m

ore

likel

y to

hav

e lo

w

vita

lity

(AO

R =

1.2

2 an

d 1.

42; A

OR

= 1

.30

and

1.55

)

Car

com

mut

ers

in t

he <

30 a

nd 3

0- t

o 60

-min

ute

cate

gori

es w

ere

mor

e lik

ely

to

have

sic

knes

s ab

senc

e >

5 d/

year

(A

OR

=

1.15

and

1.2

7)

Low

men

tal h

ealth

was

not

sig

nific

antly

as

soci

ated

with

com

mut

ing

mod

e an

d tim

e

(con

tinue

d)



11

Aut

hor

(dat

e) /

Qua

lity

Scor

eSt

udy

Des

ign

Sam

ple

Age

(ye

ars)

Act

ive

Tra

vel/

Com

mut

ing

PA

Cla

ssifi

catio

nH

ealth

Out

com

e In

dica

tors

Adj

uste

d C

onfo

unde

rsM

ain

Find

ings

Hou

et

al28

(2

004)

/6C

ase-

cont

rol

Cas

e: 9

31;

cont

rol:

1552

adu

lts;

Shan

ghai

, C

hina

30-7

4 (r

ange

)M

ET h

/wk

scor

e: lo

w

(<48

.3);

med

ium

(48

.3-

94.3

); hi

gh (

>94

.3)

Col

on c

ance

rA

ge, e

duca

tion,

fam

ily

inco

me,

mar

ital s

tatu

s,

tota

l ene

rgy

inta

ke, r

ed

mea

t in

take

, car

oten

e in

take

s, fi

ber

inta

kes

Col

on c

ance

r ri

sk w

as s

igni

fican

tly r

educ

ed

amon

g th

ose

with

hig

h-co

mm

utin

g PA

(m

en,

AO

R =

0.5

2, 9

5% C

I = 0

.27-

0.87

; wom

en,

AO

R =

0.5

6, 9

5% C

I = 0

.21-

0.91

)T

hose

with

hig

h-co

mm

utin

g PA

for

at le

ast

35 y

ears

(m

en, A

OR

= 0

.34,

95%

CI =

0.

09-0

.76;

wom

en, A

OR

= 0

.31,

95%

CI =

0.

07-0

.72)

W

omen

with

2 a

dditi

onal

co

nfou

nder

s: n

umbe

r of

pr

egna

ncie

s, m

enop

ausa

l st

atus

Shep

hard

15

(200

8)

Nar

rativ

e re

view

3 st

udie

sA

dults

2 St

udie

s: c

yclin

g to

w

ork;

1 s

tudy

: wal

king

/cy

clin

g to

wor

k

All-

caus

e m

orta

lity

2 St

udie

s ad

just

ed

conf

ound

ers

All-

caus

e m

orta

lity

was

inve

rsel

y co

rrel

ated

w

ith c

yclin

g to

wor

kSp

endi

ng ≥

15 m

inut

es w

alki

ng/c

yclin

g to

wor

k w

as a

ssoc

iate

d w

ith r

educ

ed a

ll-ca

use

and

card

iova

scul

ar m

orta

lity

Abb

revi

atio

ns: P

A, p

hysi

cal a

ctiv

ity; A

OR

, adj

uste

d od

ds r

atio

; CI,

conf

iden

ce in

terv

al; M

ET, m

etab

olic

equ

ival

ent.

Tab

le 5

. (co

ntin

ued)




tool.13 This assessment tool was adapted and used in the present systematic review (see Table 2) with criterion 3a modified to replace “physical activity” with “cardiovascular health” or “other health outcome.”

The study types of the 12 selected individual studies varied and included 2 intervention stud-ies (1 RCT and 1 quasiexperimental study, both using cycling to work as an intervention) for adults; 2 longitudinal studies for school children with follow-up periods of 2 and 6 years, respec-tively; 2 case-control studies for adults; and 6 cross-sectional studies for either school children or adults. Sample sizes of these studies were reasonable (mean sample size n = 2668), except for 2 intervention studies (n = 48 and n = 80, respectively). Most studies defined active transport as walking or cycling, but measured walking, cycling, car or motorcycle use, and public transport use (bus or train) separately. Health outcome indicators were measured objectively in all studies. The missing data were lower than 20% in most studies, and in most studies, more than 1 con-founder was adjusted for in the data analysis. Based on the quality assessment tool, the average score of 13 selected articles was relatively high: 5.92 out of 10 (minimum score = 4; maximum score = 8).

Active Transport and Body Weight

In all, 5 studies presented associations between active transport to school and school children’s body weight16-20 (Table 3). Of these, 4 were of cross-sectional design, and only 1 was a longitu-dinal study. Body weight status was assessed by body mass index (BMI) or BMI z-score or cat-egorized as overweight or obesity.

Active transport was defined as walking or cycling to school, and inactive transport was defined as using a car or motorcycle or public transport to school in 3 studies.16,18,20 Two studies found an inverse association between active transport and body weight,16,18 whereas 1 found no difference in BMI among adolescents using different modes of travel to school, but those chil-dren who bicycled to school had better physical fitness than children who walked or were driven to school.20

One study using time (minutes) of walking or cycling to school per day as an exposure factor found that greater minutes of active commuting were associated with lower BMI z-score and skin fold thickness.17 One study classified travel modes to school as walking, car, and mixed modes (including public transport) and found that compared with children who were driven to school daily, children who walked to school daily were significantly less likely to be obese.19 Another study examined the association between time walking or cycling to work and body weight and found that daily time actively commuting was inversely related to mean BMI and prevalence of overweight among men26 (Table 4). The inverse associations between active transport to work or school and body weight were consistent in these studies.

Four review articles,3,4,12,13 which included 63 studies, examined the association between active transport to work or school and body weight. Most of them (58 studies) were cross-sec-tional studies. Among these studies, 35 found that more active transport to work (n = 25) or school (n = 10) was associated with lower body weight; 24 studies found no association between active transport to work or school and body weight. Surprisingly, 4 studies found that active transport to work or school was associated with higher body weight. The evidence of inverse association between active transport to work or school and body weight derived from these 4 reviews was less consistent than that in the most recent studies.

Active Transport and Cardiovascular Health

Six studies examined the relationship between active transport and cardiovascular health.21-26 Descriptive characteristics of these studies are presented in Table 4. Various study types were



Xu et al 13

used including cross-sectional study, case-control study, quasiexperimental study, longitudinal study, and RCT. Indicators of cardiovascular health were various, including cardiorespiratory fitness (CRF; maximal power output per kilogram, relative oxygen uptake, and maximal oxygen uptake), CVD risk factor (body fat/body weight/diastolic and systolic blood pressure/blood lip-ids/glucose/insulin), and incidence of myocardial infarction (MI). All cardiovascular health out-comes were measured objectively.

Two studies, 1 RCT24 and 1 quasiexperimental study,22 both using cycling to work as an inter-vention, found that cycling to work was associated with improved CRF, and the quasiexperimen-tal study also found that total cholesterol (TC), low-density lipoprotein (LDL), TC/LDL, and diastolic blood pressure decreased and high-density lipoprotein (HDL) increased significantly in the cycling group but not significantly different from the control group. One longitudinal study21 found that cycling to school was associated with better CRF and CVD risk factor profiles (lower TC, TG, TC/HDL, composite CVD risk factor score, and better glucose metabolism). Another study23 using blood lipids as an indicator of cardiovascular health also found that people who used inactive transport to get to work (car/taxi/bus) were more likely to have dyslipidemia than those walking to work, but there was no difference between walking and cycling after adjusting for confounders.

One case-control study25 examined the association between active commuting (walking/cycling) to work and risk of MI and explored the potential mediators. It was found that car com-muting was significantly associated with MI after adjusting for confounders, and the potential mediators explained 40% of the MI risk.

One cross-sectional study26 examined the impact of time walking or cycling to work or school on blood pressure. It found that the likelihood of hypertension increased with the time walking or cycling to work or school in both genders (trend test P < .05) after adjusting for confounders.

Two reviews14,15 that included 10 studies reported on the association between active transport and cardiovascular health. One meta-analysis14 that included 8 studies reported that walking or cycling to work was associated with an overall 11% reduction in cardiovascular risk. Two studies reviewed by Shephard15 reported that cycling to school benefited cardiovascular fitness, and the incidence of MI among those cycling to work was only half of that in the general population.

Overall, the evidence provided by these studies and reviews was quite consistent and sup-ported the hypothesis that walking or cycling to work or school improves CRF and reduces CVD risk factors. Only 1 study24 reported that there was no benefit of active transport on blood pres-sure, and 1 study26 reported a negative effect on blood pressure.

Active Transport and Other Health Outcomes

One cross-sectional study27 defined active commuters to work as those walking/cycling <30 minutes and classified car and public transport commuters into those spending <30 minutes, 30 to 60 minutes, and >60 minutes commuting. It found that compared with active commuters, car commuters were more likely to perceive poor sleep quality, experience everyday stress, have low self-rated health, have low vitality, and have sickness absence >5 days per year, whereas public commuters in the >60-minute category were more likely to experience perceived poor sleep qual-ity, have low self-rated health, and have low vitality after adjusting for confounders (see Table 5). Poor mental health was not significantly associated with commuting mode or time.

One case-control study28 examined the effect of active transport on colon cancer and found that colon cancer risk was significantly lower among active transport users, particularly among those who had used active transport for at least 35 years, after adjusting for confounders (see Table 5).

One review article15 included 3 studies dealing with the effect of active transport on mortality from China, Finland, and Denmark. The Chinese study found that among active commuters,




all-cause mortality was less strongly associated with walking than with cycling; the Finnish study showed that spending ≥15 min/d walking or cycling to work was associated with reduced all-cause and cardiovascular mortality in women but not in men; the Danish study noted that all-cause mortality was 40% lower in cyclists than in other commuters after adjusting for self-reported leisure-time activities.

Discussion

Strengths and Weaknesses of the Available Evidence

The present systematic review supports the hypothesis that active transport was associated with positive health status in terms of cardiovascular health, body weight, and other health outcomes (including colon cancer and all-cause mortality). However, the strength of the evidence varied. The evidence linking active transport and cardiovascular health was moderate to strong. Out of 16 studies, 15 concluded that active transport to work (n = 14) or school (n = 1) was associated with better cardiovascular health. The evidence relating active transport with lower body weight was weak to moderate, with most studies being cross-sectional and lacking consistency in the study findings, although 40 of 69 studies reported that active transport was associated with lower weight. Few studies have examined the relationships between active transport to work and other health outcomes such as mental health, cancer, quality of life, and injury.

Studies examining the association between active transport and cardiovascular health pro-vided relatively stronger evidence. The evidence that active transport was associated with better cardiovascular health was consistent. Out of 16 studies examining the association between active transport and cardiovascular health, 15 concluded that active transport to work (n = 14) or school (n = 1) was associated with better CRF, lower CVD risk factors, and lower incidence of MI. Although the sample sizes for 1 RCT and 1 quasiexperimental study were small (n = 48 and 80, respectively), most other studies had reasonable sample sizes, ranging from 334 to 3976.

In contrast, the evidence for the impact of active transport on body weight was not consistent. Out of 69 studies, 40 examining the association between active transport and body weight reported that active transport to work (n = 25) or school (n = 15) was associated with lower body weight; 25 studies found no association between active transport and lower body weight, and 4 studies found that active transport to work or school was associated with higher body weight. Almost all studies were cross-sectional studies that provided weak evidence and cannot contrib-ute to the conclusion that there is a causal effect.

There is a discrepancy in the evidence generated from 6 studies included in this review and 4 previous reviews regarding the association between active transport and body weight. This could be explained by publication bias because we did not include gray literature in the present system-atic review; it could also be a result of active travel to work (walking) not being intense or long enough to have an impact on weight.

Strength and consistency are not enough to determine causality according to Hill’s criteria.29 There are 6 other criteria assessing causation: specificity, dose-response relationship, plausibility, coherence, experiment, and analogy. Therefore, no causal effect can be concluded in relation to active transport and health outcomes based on this review. For example, not all studies included in this systematic review adjusted for other potential confounders such as diet, screen time, and leisure time physical acidity. In this review, in terms of dose response, only 2 studies found that greater minutes of walking or cycling to work or school were associated with lower BMI17,26; 1 study found that the likelihood of hypertension increased along with the time walking or cycling to work or school in both genders. Thus, a dose response relationship was not convincing. Nevertheless, active transport improving health through increasing physical activity is biologi-cally plausible and coherent. Although the present review included some experimental studies



Xu et al 15

(RCT and quasiexperimental studies), most studies included in this review were case-control or cross-sectional studies.

Few studies examined or reported the association between active transport and other health outcomes, such as mental health, cancer, and all-cause mortality, and all studies of this kind were cross-sectional or case-control studies. Therefore, these studies do not provide strong evidence.

Despite lack of causation in relation to active transport and health benefits, promoting active transport can be beneficial to human health, not only through increasing physical activity but also by reducing air pollution, road crashes, traffic congestion, and noise as a result of reduced car use.30-37 Concern that increased active transport might increase the risk of injury may not be warranted, with health benefits of active transport outweighing the injury toll. One study found that the individual injury risk per exposure hour is relatively low in active commuting (walking and cycling) when compared with recreational and competitive sports.38 Another study from the Netherlands concluded that on average, the estimated health benefits of cycling were substantially larger than the risk relative to car driving for individuals shifting their mode of transport.39

Strengths and Limitations of this Review

One of the main strengths of this review is the comprehensive and systematic inclusion and exclusion criteria and the application of a quality assessment tool. We included various study types, including RCTs, quasiexperimental studies, and longitudinal studies in this review. We focused on the actual health outcomes rather than intermediate outcomes (eg, physical activity), and most health outcomes were measured objectively, which greatly improved the quality of included studies. In addition, the present review examined the associations between active trans-port and general health outcomes specifically for school children and adults in the workforce, so that the studies included in the review have a very clearly defined measure of active transport.

However, this systematic review may be limited by the exclusion of the gray literature, and the study findings could be influenced by publication bias. This limitation was remedied by includ-ing 6 previous reviews that included some gray literature. Another limitation of this review was the inability to conduct a meta-analysis because of the heterogeneity of studies included in this review, which made it difficult to reach strong conclusions. Therefore, it is arrive at strong con-clusions and recommendations based on the current evidence.

Unanswered Questions and Future Research

In this systematic review, active transport was defined as walking, cycling, and using public transport to work or school; however, in most studies included in the review, public transport was classified as inactive transport. We believe that public transport is an important part of active transport that usually involves some walking to bus stops or train stations.2 A recent review6 reported that a range of 8 to 33 additional minutes of walking was attributed to public transport use and highlighted the fact that a greater uptake of public transport by inactive adults would likely lead to significantly greater increases in the adult population considered sufficiently active. Future research needs to focus on the effect of public transport on health.

Few studies have examined the association between active transport and a range of other health outcomes, including mental health, certain cancers, diabetes, and commuting-related injury. These also need to be explored in future research.

Furthermore, there is an obvious need for more methodologically sound studies with suffi-cient sample sizes to provide strong evidence regarding the benefits of active transport in our communities.




Conclusions

Active transport that incorporates walking and cycling to work or school is a promising way to improve people’s health, in particular cardiovascular health, through integrating physical activity into daily life. Further research is needed to examine the effect of active transport on health using stronger research designs, such as RCTs or longitudinal studies. The effect of public transport on health needs to be further investigated.

Declaration of Conflicting Interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) received no financial support for the research, authorship, and/or publication of this article.

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