Sinusoidal Compared With Constant Work Rate High Intensity Exercise Training In COPD Patients With Ventilatory Limitation

High intensity exercise training results in significant improvement in exercise
capacity in patients with COPD. However, most patients do not tolerate this
training regimen for long periods due to reduced breathing reserve and
incapacitating breathlessness. Sinusoidal high intensity exercise is a
different approach to bi-level interval training, which is the highest possible
continuous exercise (with a peak of 120% of the peak work rate in an
incremental test) that does not result in ventilatory limitation. This study
was presented at the American Thoracic Society meetings in 2010.
Based on this study we designed an exercise training study comparing sinusoidal
and cosntant work rate exercise training. We expect that an exercise training
program using sinusoidal high intensity training will result in greater
physiologic benefits than constant work rate training. This may result in a
significant improvement in exercise capacity, muscle strength in patients with
severe COPD. Improvement in exercise capacity may also improve symptoms of
dyspnea in COPD patients and subsequently ameliorate the ability to perform
activities of daily living and quality of life.

The primary outcome measure will be comparison of improvement in endurance of a
work rate initially eliciting exercise limitation after 6 minutes (calculated
from the power-duration relationship before and after training). We will also
compare improvements in critical power and curvature constant of the
power-duration relationship. Further, we will compare responses to incremental
exercise to determine whether increases in lactate threshold and peak oxygen
uptake are greater in the group assigned to sinusoidal work rate training.
Finally, we will assess increases in quadriceps strength to determine whether
the periods of high muscle tension induce adaptations that increase muscle
strength

All COPD patients will be evaluated with the following lung function and
exercise tests in the assessment week:

Visit 1: After informed consent, pulmonary function test and incremental
exercise test will be completed to assess exercise tolerance

Visit 2 &3: Two constant work rate exercise tests in each day, with at least 2
hours separating the tests, to derive the power-duration curve.

Visit 4: A constant work rate test at the critical power. After two hours of
rest, leg strength testing by means of the 1 repetition maximum of the leg
press will be determined.

After the assessment week, subjects will be randomly allocated to the
sinusoidal exercise training program (ST) or continuous work rate exercise
training program (CT). Randomization will be stratified by oxygen use ( yes or
no ) and FEV1 (>= or < 40% predicted).

Both training programs contain exercise sessions of 45 minutes each, 3 days a
week for 4 weeks. After the 4 week training program, the exercise tests
performed in the assessment week will be repeated.

The two training programs contain exercise sessions of 45 minutes each, 3 days
a week for 4 weeks. After the 4 week training program, the exercise tests
performed in the assessment week will be repeated.

Trainingstrategies
Half of subjects will exercise at a work rate equal to critical power. The
other half will exercise at a sinusoidally varying work rate such that the mean
of the sine work rate is equal to the critical power and the peak of the sine
work rate is set to 120% of peak work rate. After 3 minutes of unloaded
cycling, exercise begins with the sine wave at its trough to assure a smooth
increase in work rate. A sinusoidal period of 60 seconds will be used. The
modulating sine wave work rate forcing will be generated by a computer program
and applied to the work rate controller of electromagnetically-braked cycle
ergometers (Cateye) through digital to analog conversion

COPD patients in the study are screened by a medical doctor on the first
visit. Medical history, physical exam, pulmonary function tests, ECG and an
incremental cardiopulmonary exercise test. Patients with cardiovascular or
other comorbidity that constitutes a relative contraindication to a vigorous
exercise program are excluded.

Before every exercise test and training patients are asked for increase in
pulmonary and cardiac symptoms. Bloodpressure, heartrate and oxygen saturation
are always measured. Patients are monitored during the exercise tests,
measuring blood pressure, ECG and oxygen saturation.

During the exercise training patients are also monitored, measuring oxygen
saturation.