Exercise as it relates to Disease/Going eccentric is good for COPD patients: benefits of eccentric ergometer training

The following is an analysis of the article "Eccentric Ergometer Training Promotes Locomotor Muscle Strength but Not Mitochondrial Adaptation in Patients with Severe Chronic Obstructive Pulmonary Disease"

Chronic Obstructive Pulmonary Disease
Chronic obstructive pulmonary disease (COPD) encompasses diseases such as chronic bronchitis, emphysema and some forms of chronic asthma. A progressive condition, it destroys the walls between the lung air sacs (alveoli), reduces lung tissue elasticity and causes thickening of the airway walls and dysfunction in skeletal muscle tissue. Symptoms include breathlessness (dyspnea), coughing and excess mucus production.



Sufferers have a reduced quality of life and their ability to carry out activities of daily living (ADLs) is adversely affected.

The condition is diagnosed, classified and monitored using spirometry. Classification is shown below*.


 * In patients with FEV1/FVC < 0.7; GOLD = Global Initiative for Chronic Obstructive Lung Disease; FEV1 = Forced Expiratory Volume in 1 second; FVC = Functional Vital Capacity

Eccentric exercise
Eccentric contractions occur when muscles lengthen under load. More force is produced but oxygen demand is reduced compared with concentric contractions. As COPD patients have a reduced exercise tolerance caused at least in part by dsypnea ; using a training modality that consumes less oxygen and produces more muscle activation is appealing. However, eccentric exercise was perceived as dangerous and damaging and so wasn't used in the management of chronic diseases until recently. Recent trials and reviews have determined that eccentric exercise is safe if a familiarisation period and gradual increase in load is utilised.

Where does this study fit?
Several studies have examined the feasibility of eccentric training for COPD. This study is one of the first to attempt to characterize muscle adaptations from eccentric compared with concentric training.

Where is the research from?
A large team of 14 carried out the study. They were from:
 * McGill University - a well respected Canadian institution
 * Université du Québec à Montréal - ranked in the top 100 Young Universities
 * Centre Hospitalier Universitaire de Clermont-Ferrand - a teaching hospital where researchers have authored at least 800 papers

Study participants were drawn from a clinic at the Montreal Chest Institute which is part of the McGill University Health Centre.

The lead author has written a number of other papers on exercise and respiratory diseases.

There was no information provided on conflicts of interest.

The study was carried out on Canadians, however the results are still applicable to an Australian population.

What kind of research was this?
The study was a randomised controlled trial (RCT). RCTs are considered the best way to examine the effects of a treatment. However, if the sample size is small, treatment groups may have different characteristics, which appears to have happened in this trial.

The participants were probably unblinded and its likely they were aware which protocol they were allocated to; it is unknown if the researchers were blinded.

The effects of eccentric versus concentric ergometry training on COPD patients was investigated; no "control" group was included.

What did the research involve?
Researchers recruited 24 men aged 50-80 with moderate to very severe COPD. Fifteen patients consented to muscle biopsies and continued with the trial.

The following tests were carried out at the start and finish of the 10 week training program:
 * lung function
 * cardiovascular fitness
 * body composition
 * muscle strength
 * serum creatine kinase levels (an indicator of muscle damage)
 * muscle tissue adaptations (mitochondrial markers)

Participants were randomised to an Eccentric Ergometer Training (EET) (n=8) or a Concentric Ergometer Training (CET) (n=7) protocol. The CET group used standard recumbent bikes. The intensity was set at 60-80% of the peak workrate determined during the initial testing. The EET group used motorised bikes that drove the pedals backwards; participants were asked to resist the motion. The target workrate was four times that of CET to ensure both groups would exercise at a similar relative intensity.

Training was conducted for 30 minutes 3 times a week.

What were the basic results?
The EET group trained at a workrate that was 3 times greater than the CET group, but they felt less fatigued.

Other notable results were:
 * A reduction in body fat in the EET group; no change in BMI (no change in either body fat or BMI in the CET group)
 * Muscle strength increased in the EET group; no change in muscle size (CET group had a slight increase in size, no change in strength)
 * No indications of muscle damage
 * No changes in mitochondrial markers in the EET group (significant changes in the CET group)

What conclusions can we take from this research?
EET is safe and effective for COPD patients if the protocol is adhered to. Patients can exercise at a high workrate, but with a low perceived rate of exertion. As eccentric exercise feels relatively effortless compliance and adherence is likely to improve.

Clearly eccentric training can result in significant strength gains. However, as functional outcomes were not assessed, its impossible to say whether the increases in strength translate to improvements in the ability to carry out ADLs.

Its not surprising that no mitochondrial adaptations were found in the EET group. One of the hallmarks of this type of exercise is a lower metabolic demand and oxygen consumption, there may simply not be the impetus for mitochondrial adaptation.

The small sample size and the inclusion of only male patients with more severe COPD limits the study's applicability. Specialized equipment is required which will affect the adoption of this training modality.

Directions for future research:
 * Training that combines EET and CET
 * The effects of long term EET programs
 * Examination of functional outcomes from EET

Practical advice
Utilizing eccentric ergometry training, COPD patients can exercise at high workrates with minimal fatigue and dyspnea. The training can result in significant improvements in strength. The requirement for specialised equipment may confine EET to the clinic, however there are other forms of eccentric exercise that may be suitable such as downhill walking outdoors or on a treadmill.