-0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0

-1.0

-0.5

0.0

0.5

1.0

1.5

0.100 L

-0.100 L

-0.0

5 m

/s

0.0

5 m

/s

Cynthia Otfinowski1, Joyce Fung1,2, Jadranka Spahija1,2,3

1. School of Physical and Occupational Therapy, McGill University; 2. Feil/Oberfeld/CRIR Research Centre, Jewish Rehabilitation Hospital;

3. Research Center, Hôpital du Sacré-Coeur de Montréal.

Montreal (Quebec) Canada

RESULTS

References 1. Lanini B, et al. (2003). Chest wall kinematics in patients with hemiplegia. American Journal of Respiratory and

Critical Care Medicine, 168:109-13.

2. MacKay-Lyons et al. (2006). Cardiovascular fitness and adaptations to aerobic training after stroke. Physiotherapy

Canada, 58(2):103-13.

3. Teixeira da Cunha-Filho I, et al. (2003). Differential responses to measures of gait performance among healthy

and neurologically impaired individuals. Arch Phys Med Rehabil 84:1774-9.

4. Mercier J, et al. (1994). Energy expenditure and cardiorespiratory responses at the transition between walking

and running. Eur J Appl Physiol, 69:525-9.

Acknowledgements Staff at JRH: Claire Perez, Valeri Goussev, Christian Beaudoin, Igor Sorokin, Gevorg Chilingaryan

Assistance with data collection: Natalie Levtova, Karan Dev, Semra Orguz, Patrick Smallhorn,

Natalie Diez d’Aux, Feng Shang He, Lyonciny Li, Yu Ren, Anuja Darekar.

Participant recruitment: Jewish Rehabilitation Hospital, Cummings Centre

Institutional support: Jewish Rehabilitation Hospital, CRIR, McGill University

Author contact Cynthia Otfinowski, MSc candidate. Email: cotfinowski@gmail.com.

To evaluate how increased walking speed impacts the depth of breathing (tidal

volume) in healthy and individuals with stroke and the effect of deep breathing

on walking speed.

PURPOSE

Reduced depth of breathing and walking speed may occur post-stroke

secondary to hemiparesis1,2.

Higher oxygen cost with hemiparetic gait may result in similar ventilatory

requirements for people with stroke who walk slower than neurologically intact

adults3.

Depth of breathing increases with fast walking in healthy people but it is

unknown if this adaptation occurs post-stroke4.

Understanding the relationship between walking speed and tidal volume may

provide insight into limitations of exercise capacity and community ambulation in

people post-stroke.

RATIONALE

CONCLUSIONS / IMPLICATIONS People post-stroke are able to increase depth of breathing in standing similar

to the control group, suggesting voluntary control of breathing is intact.

Attempting to increase walking speed while breathing deeply results in a

decrease in tidal volume in persons with stroke, suggesting the respiratory

muscles might prioritize postural stability more than depth of breathing while

walking fast.

Walking at a comfortable pace and deep breathing may be beneficial for

people post-stroke to optimize tidal volume and walking speed.

Table 1: Demographics and baseline measures of

persons with stroke and controls.

*Missing data for 10 m walking tests and pulmonary function tests were due to either machine

malfunction or scheduling issues. Some assessments were not made on the initial participants in

each group (n=5) during pilot testing.

Figure 2: Lab set-up: A) equipment; B) virtual reality screen viewed by participants.

Outcome measures:

• Gait speed (m/s) (foot markers

captured by VICON MX System)

• Air flow (pneumotachograph)

integrated to obtain tidal volume (L)

A B

Ethics approved by the Centre de recherche interdisciplinaire en réadaptation

du Montréal métropolitain (CRIR).

An interaction between breathing and walking was significant for persons with

stroke (p=0.02 ANOVA).

Fast (compared to comfortable) pace walking while deep breathing decreased

tidal volume by 8% (p=0.003 post-hoc) in people with stroke.

Figure 5: Tidal volume changes while breathing deeply and increasing walking speed

from comfortable to fast.

While breathing deeply and walking faster, tidal volume

decreased in persons with stroke.

Statistical analysis:

Data for the three conditions (QST, DST, QF) were analyzed for each group

using an one-way repeated measures ANOVA for tidal volume.

Data for the four walking conditions (QC, DC, QF, DF) in each group (stroke,

control), were analyzed using two-way repeated measures ANOVA for each

outcome measure (tidal volume and walking speed). Data was transformed

(except tidal volume for people post-stroke) to meet normality criteria.

Rank sum test was used to compare groups (stroke, control).

METHODS

Gait speed

-0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0

-0.5

0.0

0.5

1.0

1.5

2.0

0.100 L

-0.100 L

0.0

5 m

/s

-0.0

5 m

/s

Increasing depth of breathing had a significant effect (p=0.040, ANOVA;

p=0.016; post-hoc contrast) on increasing comfortable walking speed in people

with stroke when the outlier was removed.

With the removal of the two outliers in the control group, the main effect for

breathing is significant (p=0.020) but not while walking a comfortable pace.

Outlier

Chan

ge

in tid

al vo

lum

e (

L)

Change in walking speed (m/s)

Figure 4: Change in walking speed when increasing from quiet to deep breathing.

While walking a comfortable pace and breathing deeper,

75% of participants with stroke walked faster.

Stroke

Control

Table 2: Results for tidal volume and walking speed.

Figure 1: Experimental design. Conditions A, B, C, D were randomized according to

a balanced Latin-square design.

2 groups: People with stroke and age- and gender-matched healthy adults.

Each walking trial is 2 minutes long with a 5 minute rest in sitting between trials

Vital capacity is the lung volume between maximum inspiration and expiration.

Tidal volume is the lung volume during a breath cycle.

Off-line data analysis:

Signals obtained from the pneumotach and VICON Nexus software were

processed using a customized script written in C++, to provide gait speed and

tidal volume data per breathing and walking cycle. These data were averaged

for each individual in each condition.

The average tidal volume and gait speed for each individual was used for

statistical analysis.

Contrary to our expectations, people with stroke increased tidal volume

voluntarily in standing from quiet to deep breathing (p<0.001).

Similar to our expectations, tidal volume increased with exercise, when

comparing standing to fast walking while breathing quietly (p<0.05).

People with stroke have lower tidal volumes compared to the control group

while walking fast but similar in standing.

Figure 3: Tidal volume in each condition in people with stroke or the control group.

Tidal volume increases with deep breathing or fast walking

in persons with stroke and the control group.

0.000

0.500

1.000

1.500

2.000

2.500

3.000

3.500

4.000

VC QST DST QC QF

Tid

al vo

lum

e (

L)

2.50

2.00

1.50

1.00

0.50

0.00 Quiet

Breathing

Comfortable

Walking

Quiet

Breathing

Fast

Walking

Quiet

Breathing

Standing

Deep

Breathing

Standing

Vital

Capacity

Standing

3.00

3.50

4.00

p<0.001

p=0.040

p=0.025

Outlier

Chan

ge

in tid

al vo

lum

e (

L)

Change in walking speed (m/s)

Stroke

Control

Variables Stroke Control

Median (range) (n=) Median (range) (n=)

Age (years) 56 (44-71) 12 54 (41-67) 11

Gender 7 males : 5 females 12 7 males : 4 females 11

Body mass index (kg/m2) 28 (21-30) 12 24 (19-30) 11

Forced expiratory volume in 1 sec

(FEV1) (%)

97 (57-121) 7 104 (87-107) 4*

Forced vital capacity (FVC) (%) 97 (55-129) 7 102 (87-114) 4*

FEV1/FVC (%) 81.3 (75.3-93.9) 7 81.8 (72.9-83.7) 4*

Smoking history (pk*yrs) 10 (0-57) 7 0 (0-45) 6

Current smoker? 1 yes: 6 no 7 1 yes: 5 no 6

International Physical Activity

Questionnaire

1418 (281 - 14536) 7 2172 (660-13311) 6

10 m gait speed (comfortable) m/s 0.61 (0.32-1.30) 12 1.41 (1.12-1.87) 10*

10 m gait speed (fast) m/s 0.81 (0.40-1.73) 12 2.06 (1.75-2.63) 10*

6 minute walk test (m) 330 (106-525) 7 632(483-775) 6

Gait aid 4 none; 8 cane 12 11 none 11

Orthosis 6 none: 4 ankle foot: 2

ankle supporting

12 11 none 11

Paretic side 9 right: 3 left 12 n/a -

Time since stroke (months) 27 (8-200) 12 n/a -

Chedoke-McMaster Stroke Assessment

(leg/ foot)

(3-6) leg; (2-5) foot 7 n/a -

Variable Subject Quiet

Breathing

Comfortable

Walking

Deep

Breathing

Comfortable

Walking

Quiet

Breathing

Fast

Walking

Deep

Breathing

Fast

Walking

Tidal volume (L) Stroke 0.922 (0.259) 1.539 (1.180) 0.954 (0.249) 1.181 (0.924)

Tidal volume (L) Control 1.012 (0.239) 2.08 (0.573) 1.228 (0.324) 2.164 (0.569)

Gait speed (m/s) Stroke 0.40 (0.23) 0.48 (0.22) 0.51 (0.30) 0.59 (0.33)

Gait speed (m/s) Control 1.00 (0.28) 1.12 (0.31) 1.53 (0.14) 1.58 (0.21)