1. Clinical assessment of peripheral
muscle function in patients with
chronic pulmonary disease
Journal presentation
Shifa Manhal

2. Authors and Affiliations
Authors
• Jordi Vilaro, PhD
• Roberto Rabinovich, MD
• Jose Manuel Gonzalez-deSuso, MD
• Thierry Troosters, PhD
• Diego Rodriguez, MD
• Joan Albert Barbera, MD
• Josep Roca, MD
Affiliations
• Servei de pneumologia, hospital clinic
• Universitat de Barcelona , Spain

3. Abstract
Objectives :
• Correlation of muscle function , muscle mass
and endurance and exercise tolerance in
chronic obstructive pulmonary disease.

4. Abstract
• Design :
sixteen COPD patients (FEV1 – 38 ± 15% predicted) and 6
controls underwent magnetic resonance imaging of the thigh,
muscle strength and endurance, and exercise tolerance
assessments.

5. Abstract
Results:
• Six COPD patients presented with reduced thigh
mass (COPDLQ)
• 10 patients presented with normal quadriceps mass
(COPDNQ) and all controls had identical mass
distribution.
• COPDLQ had lowered muscle function and lowered
exercise tolerance than both controls and COPDNQ.
• Muscle strength to muscle mass was similar among
COPD patients and controls.

6. Abstract
Results:
• Endurance to muscle mass ratio was lower in COPD
than in controls.
• Half time phosphocreatine recovery was also slower
than in controls.

7. Abstract
Conclusion:
• Impaired muscle strength was explained by
reduced muscle mass, but it did not account
for abnormal muscle endurance. The latter
seems associated to impaired O2 transport
/O2 utilization, resulting in altered muscle
bioenergetics .

8. Introduction
Nitroso –
redox
muscle disuse
disequilibrium
of the system
Peripheral
Cell hypoxia muscle
abnormalities
ADL, HRQOL
and disease Limited
Systemic
inflammation prognosis in exercise
COPD tolerance
patients

9. Background
• Muscle strength and oxygen uptake kinetics in
COPD patients with preserved muscle mass
are comparable with that of healthy sedentary
controls.
• Impaired quadriceps strength seen in COPD
patients has been explained by reduction of
muscle mass.
• Abnormal muscle bioenergetics seem to
account for impaired muscle endurance ,
independently of the amount of muscle mass.

10. Background
Limitation in
o2 transport
both at central
and peripheral
level
Altered
muscle
bioenergetics
in COPD
patients
Impaired
muscle O2
utilization

11. Background
• Previous studies of muscle endurance and strength in
COPD suggest that muscle dysfunction as analyzed
through strength tests may give only limited
information about intrinsic muscle exercise capacity .
• In this study different approaches to assess muscle
strength have been analyzed.
• The information from the above approaches have
been compared with information obtained from
muscle bioenergetics assessed by phosphorus-
magnetic resonance spectroscopy (P-NMRS) and
exercise tolerance.

12. Methods
16 COPD patients
and 6 healthy
sedentary controls
Assessment of
Pulmonary Muscle function thigh muscle mass
Exercise testing
function test test by magnetic
resonance imaging

13. Pulmonary Function test
• Test performed at rest
• Forced spirometry
• Lung volume measure
• Single breath diffusion capacity

14. Muscle function test
Muscle
function tetst
Isokinetic peak
torque (isokin)
Isometric force
production
(isome)
One repetition
maximum
strength test
(RM)

15. Muscle function test
• Isokin and isome measurements were done using isokinetic
dynamometer (cybex 6000)
• Isokin peak torque (Nm) was taken as the heighest value of
two trials with five knee extensions at the angular speed of 60
degree/sec each.
• Best isome peak power (N) from three acceptable trials
aiming at maximal knee extension/contraction against a static
arm lever at 60 degrees was selected.

16. Muscle function test
• RM measured the maximum amount of weight
that can be lifted in a single repetition.
• Handgrip strength of the dominant hand using
a handheld dynamometer . Best value of three
reproducible maneuvers was used in the
analysis.
• Muscle bioenergetics was assessed by P-NMRS
using a specially designed cycle ergometer

17. Assessment of thigh muscle mass by
magnetic resonance imaging
• Left leg MRI from the isquio-femoral joint to the inferior
femur condyle.
• Calculation of thigh area /volume was performed by a single
observer using an image analyzing computer program.

18. Exercise Testing
• Incremental exercise test with cycle
ergometer.
• Radial artery cannulation done to all subjects.
• Subjects were asked to pedal as much as
possible against an incremental load , until
exhaustion .
• A gas analyzer was used to continuously
measure breath by breath oxygen
consumption(VO2), carbon dioxide production
(Vco2), minute ventilation (Ve) and heart rate.
•

19. Exercise Testing
Arterial blood samples were taken every 3
minutes to assess :
• Arterial lactate concentration
• Oxygen saturation
Dyspnea and leg discomfort were scored at the
beginning and the end of the test.

20. Exercise Testing
• Two 6 min walk test were performed by patients in a
corridor of 90m length.
• They were asked to walk as far as possible during 6
minutes with standardized encouragement.
• The best results from two trials were used for data
analysis.

21. Statistical analysis
• Students unpaired t test
• Pearsons regression analysis
• Post HOC
• Analysis of variance

22. Results – study groups
• COPD patients showed severe airflow obstruction with
moderate hypoxemia , whereas the control group
presented normal lung function.
• In regard to thigh muscle mass index COPDNQ showed
identical distribution to the six healthy identical
sedentary controls . COPDLQ had a lower MMI in
comparison to both COPDNQ and controls.
• COPDLQ showed higher functional impairment than
COPDNQ indicating more advanced disease.
• COPD patients as a whole group showed lower exercise
tolerance than healthy sedentary controls assessed by
incremental cycling exercise and timed walking test.

23. Results – endurance and strength vs
Mass
• Quadriceps endurance was significantly lower in
COPDLQ than in COPDNQ. This variable was also lower in the
overall COPD group than in controls.
• Muscle strength was lower in COPDLQ than in COPDNQ .
Statistically significant difference in muscle strength were
also seen between the whole COPD group and controls.
• Difference in muscle strength between controls and COPDNQ
were only seen in isome and handgrip measurements.
• Quadriceps isokinetic strength showed significant
associations with isometric strength, repetition maximum
and handgrip strength.

24. Results – associations with exercise
tolerance
• Significant association between 6MWD and
different variables indicating pulmonary and
skeletal muscle function.

25. DISCUSSION
• Impairment of muscle strength is a direct consequence of
muscle mass wasting . This phenomenon is explained by the
combined effects of muscle disuse and systemic effects
leading to myopathy.
• Quadriceps endurance and muscle bioenergetics were
consistently abnormal in COPD patients. This is because
muscle endurance is explained by both oxygen transport and
muscle oxidative capacity.
• This study stresses the relevance of muscle endurance
impairment in COPD patients and reinforces the for a
separate assessment of muscle strength and muscle
endurance.

26. Assessment of muscle strength vs
muscle mass
• Isometric strength is the most sensible method to detect
differences among subsets of subjects.
• Repetition maximum and handgrip strength can be
considered for routine clinical use.
• Assessment of muscle mass is a good substitute for muscle
strength in the clinical setting. Standardized measurements of
bioelectrical impedance is suggested as an appropriate
method for extensive noninvasive clinical use.

27. Clinical impact
• Assessment of exercise tolerance provides an
integrative evaluation of pulmonary and peripheral
factors determining aerobic capacity.
• This study shows high colinearity between muscle
endurance , muscle strength and muscle mass as
covariates of exercise tolerance .
• 6MWD is most suitable test for extensive clinical
application.
• Further scope for research – evaluate the potential of
alternative tests to assess muscle endurance in the
clinical area.