. Author manuscript; available in PMC: 2022 Dec 1.

Published in final edited form as: Neurosci Biobehav Rev. 2021 Oct 13;131:923–940. doi: 10.1016/j.neubiorev.2021.10.013

Table 5.

A summary of investigations examining the relationship between fitness and structural connectivity.

Author, year	Participant		Fitness assessment	Analysis Method	Results
Author, year	n, Subjects	Mean age (year)	Fitness assessment	Analysis Method	Results
Marks, 2007	13 YA and 15 OA	YA: 24±3 OA: 69.6±4.7	age, sex, BMI, and self-reported PA.	Seven hand drawn ROIs	Link between ↑ CRF and ↑ FA in UF and CM for OA and YA
Marks, 2011	15 OA	66±6	$\dot{V} O_{2 \max}$	Hand drawn CM ROIs	Link between ↑ CRF and ↑ FA of left middle cingulum
Johnson, 2012	26 OA	64.8±2.8	$\dot{V} O_{2 \max}$ , total time on treadmill, 1-min HR recovery	TBSS	Link between ↑ FIT and ↓ RD of the CC
Liu, 2012	9 AC and 6 INAC OA	AC: 62.1±2.6 INAC: 72.3±2.7	$\dot{V} O_{2 \max}$	Automated Voxel-Wise analysis	Link between ↑ CRF and ↑ FA in tracts connecting prefrontal and parietal brain regions
Tseng, 2013	10 MA and 10 SED OA	MA: 72.2±5.3 SED: 74.5±4.3	$\dot{V} O_{2 \max}$	TBSS	MA > SED OA 1) ↑ FA in R SCR, both sides of SLF, R IFOF, and L ILF 2) ↓ MD of L PTR and L cingulum HIP
Wang, 2013	13 YA EG, 14 YA	EG: 20.5±3.2 YA: 22.3±2.7	No information	Tractography, Global and Regional network analysis	1) ↑ anatomical connection density in sensorimotor, attentional and default mode systems in EG. 2) ↑ FA in bilateral CST of EG.
Burzynska, 2014	88 low fit OA	65±4	$\dot{V} O_{2 \max}$ and 7-day actigraphy data	TBSS	1) Link between ↑ SED time and ↓ FA of PRHIP WM 2) No link between SC and FIT
Tian, 2014^a	276 OA	83±2.7	10-year PA history questionnaire	TOIA	No difference in WM tracts between AC and SED groups
Tian, 2014^b	164 OA	82.9±2.6	400-meter walk test	TOIA	Link between ↑ FIT and ↑ FA of CM
Tian, 2015	90 OA	87.4±2.3	number of steps	TOIA	Link between ↑ PA and ↑ FA in WM frontal and temporal areas 1) Link between ↑ PA and whole brain ↑ FA 2) FA mediates positive relationship between CRF and global cognition
Hayes, 2015	32 YA and 27 OA	YA: 21.1±3.1 OA: 63.4±6.4	$\dot{V} O_{2 \max}$	TBSS
Zhu, 2015	565 MA	81.3±2.5	MDT (5 year prior)	TOIA	Link between ↑ FIT and ↑ FA (individual tracts not analyzed)
Oberlin, 2016	Study 1: 113 OA Study 2: 154 OA	Study 1: 66.1±5.7 Study 2: 65.6±4.6	$\dot{V} O_{2 \max}$	TBSS	1) Link between ↑ FIT and ↑ FA in ACR, AIC, fornix, CM, and CC 2) FA mediated the link between FIT and spatial memory
Smith, 2016	88 OA with APOE-ε4 (LRHP: 21, LRLP: 33, HRHP: 20, HRLP: 14)	LRHP: 76±4.7 LRLP: 73.5±4.7 HRHP: 73.1±4.4 HRLP: 74±4.2	SBAS	TBSS	1) Link between ↑ PA and ↑ FA and ↓ RD in the SLF, SS, GCC, fornix, IC, and CR for APOE-ε4 carriers 2) Opposite trend in APOE-ε4 noncarriers 1) Link between ↑ FIT and ↑ FA in LF, FOF, and CC 2) Link between ↑ FIT and ↓ MD and RD in LF, FOF, and CC Link between↑ HWT and ↓ whole brain AD and RD and cognition ↑ FA predictive of PA adherence No link between PA and FA or MD 1) ↓ PA ↑ MD of uncinate fasciculus over time Link between ↑ FIT and ↑ whole brain FA ↑ FIT linked to ↑ FA in R CM, HIP, and L CP
Teixeira, 2016	22, OA with aMCI	68.5	$\dot{V} O_{2 \max}$	TBSS
Best, 2017	141 OA	82.5±2.5	Self-reported 10-year walking time	Whole Brain TOIA
Gujral, 2018	105 OA	66.6±5.7	PASE	TBSS
Maltais, 2019	277 OA	74.7 + 3.9	Self-report questionnaire	TBSS
Opel, 2019	1048 YA	28.8±3.7	2-min walk test	TBSS
Chen, 2020	56 OA	59.1±4.3	$\dot{V} O_{2 \max}$	TOIA
Harasym, 2020	24 PM women	59.5±3.5	$\dot{V} O_{2 \max}$	TBSS	Link between ↑ CRF and ↑ FA of S1 1) ↑ PA mediates relationship between ↑ age and ↓ FA in the GCC, UF, and EC 2) ↑ FA of GCC mediated relationship between ↓ age and ↑ RT
Strömmer, 2020	399, YA and OA	Range from 18–87	Self-reported PA levels	TOIA
Wolf, 2020	44 OA	69+7.3	7-day actigraphy data	TBSS	1) No associations between PA and MD or FA 2) Interaction between PA and ↑ age linked to global MD 1) ↑ FA in the GCC, SCR, ACR, AIC, LF, FOF, UF, CM, and fornix in the MA group compared to MS. 2) Link between ↑ FIT and ↑ FA in both MA and YA groups
Tarumi 2021	30 MT, 30 MS, and YA	YA: 32±6 MT: 54±4 MS: 54±4	$\dot{V} O_{2 \max}$	TBSS

Notes: OA, older adults; YA, younger adults; AC, active; INAC, inactive; MA, master athletes; MT, middle aged trained, MS, middle aged sedentary, SED, sedentary; EG, elite gymnasts; APOE-ε4, apolipoprotein E epsilon 4 allele; LRHP, Low Risk (non--APOE-ε4 carrier) High PA; LRLP, Low Risk (non--APOE-ε4 carrier)-Low PA; HRHP, High Risk (APOE-ε4 carrier)-High PA; HRLP, High Risk-Low PA; PM, post-menopausal; TC, Tai Chi group; W, walking group; BMI, body mass index; aMCI, amnestic mild cognitive impairment; PA, physical activity questionnaire; CRF, cardiorespiratory fitness; $\dot{V} O_{2 \max}$ , maximal oxygen consumption; MDT, maximal duration treadmill test; SBAS, Stanford Brief Activity Survey; PASE, Physical Activity Scale for the Elderly; ROI, region of interest; CM, cingulum; TBSS, tract based spatial statistics; TOIA, tract of Interest analysis; FA, fractional anisotropy; CC, corpus callosum; MD, mean diffusivity; AD, axial diffusivity; RD, radial diffusivity; UF, uncinate fasciculus; R, right; SCR, superior corona radiata; SLF, superior longitudinal fasciculus; IFOF, inferior fronto-occipital fasciculus; L, left; ILF, inferior longitudinal fasciculus; PTR, posterior thalamic radiation; HIP, hippocampus; PRHIP, parahippocampal; WM, white matter; SC, structural connectivity; FIT, fitness; ACR, anterior corona radiata; AIC, anterior internal capsule; CP, cerebral peduncle; SS, sagital stratum; GCC, genu of corpus callosum; IC, internal capsule; CR, corona radiata; LF, longitudinal fasciculus; FOF, fronto-occipital fasciculus; CST, corticospinal tract; HWT, historic walking time; S1, somatosensory region; EC, external capsule; RT, response time.