What is COPD?

COPD is a preventable and treatable disease, caused by exposure to toxic particles or gases, such as those inhaled during smoking or from pollutants in the air, leading to its progressive respiratory symptoms and limiting expiratory airflow (dyspnea) (GOLD, 2017)

It has been recognised as a combination of conditions. These conditions affect parts of the respiratory system such as emphysema, where air sacs (alveoli) in the lungs are damaged, and chronic bronchitis, when the bronchial tubes are inflamed (WHO, 2017 and NHS, 2016). The disease’s global mortality in 2010 was 2.8 million deaths, which was lower than the rate in 1990 of three million, then moving up to an estimation of 3.17 million deaths in 2015 (WHO, 2017 and Burney et al., 2015), Which highlights the importance of prevention.

Management using exercise: 

As 80% of clinical cases are a result of smoking, smoke cessation may seem the best preventative and managing measure, but it is not the only causation nor the singular solution. In addition, COPD is mainly diagnosed amongst the elderly, and after the underlying conditions have progressed, there is a need for managing the disease. GOLD advises that pulmonary rehabilitation (PR) should be part of patient management. PR is an intervention programme, including many aspects such as behaviour therapy and exercise training. (GOLD, 2017)

Physical activity is musculoskeletal movement which occurs when the body spend energy (ATP). Whereas exercise is a type of physical activity defined by the structure of movement, recurrence and planning, leading to muscle, bone and circulation maintenance (Spruit et al., 2016). According to GOLD guidelines, exercise training is a key contributor to PR, and have multiple types (Endurance training, strength exercise, groups sports, etc.), each type affect patients and improve quality of life (Levin, Netz and Ziv, 2017).COPD patients have reduced exercise capacity due to dyspnea as the increased energy demand required for exercise relies on oxygen. (Aliverti and Macklem, 2008 and Spruit et al., 2013)

WHO warned from physical inactivity implications, others highlighted its association with many health complications (Febbraio, 2017 and WHO 2002). As a result, physical activity and exercise are now being recommended by many professionals. (Febbraio, 2017, NHS, 2018, Khan et al., 2012 and Garber et al., 2011). In addition, researchers suggested that exercise contribute to several health benefits such as cardiorespiratory fitness (increased VO2 and an improved pulmonary ventilation), in line with cardiovascular health, musculoskeletal maintenance and mental health (Febbraio, 2017; Khan et al., 2012; Ortega et al., 2002 and Rimes et al., 2015).

Exercise benefits:

A study compared the effects of different types of exercise (Strength training, n = 17, endurance training, n = 16 and combined training = 14) on patients with COPD. A twelve weeks, three days a week, intervention was completed in each of the groups. The study didn’t include a control group, however, did complete baseline measurements to compare the findings with it, and for patients to act as their own control. Strength training intervention consisted of multiple weight lifting exercises for muscle groups in the upper and lower body. Only lower extremities exercise protocol was given in endurance training. The study found that VO2 during endurance exercise has significantly improved (mean ± standard deviation) (1.48 ± 0.44 L/min) from baseline (1.32 ± 0.4 L/min). Strength and endurance training improved muscle power output (strength), after the intervention, (baseline strength training Wmax 50 ± 19W, after 55 ± 20 W, baseline endurance training 39 ± 18 W, after 50 ± 18), with significance only observed in endurance training patients. Whereas the combined group presented non-significant improvements in VO2 and Wmax, (baseline VO2 1.26 ± 0.26 L/min, after 1.34 ± 26 L/min, baseline Wmax 41 ± 16 W, after 46 ± 9 W) (Ortega et al., 2002). The study was detailed; the sample size was small, and each group completed different exercise protocol (different muscle groups), which may be the reason why they were unable to discover significance in other groups than endurance exercise. This may also be an indication that lower extremities training seem to be more beneficial to patients with COPD instead of combined training.

A meta-analysis reviewed 160 randomised controlled trials (7487 participants), found that training exercise may significantly improve cardiorespiratory fitness. The analysis did not include much information about VO2, however, when looking at the conducted studies which included these measurements, they collectively reported that VO2 max was improved or did not change after the intervention. Indicating that the exercise intervention had a positive impact on pulmonary ventilation. The studies didn’t reflect large sample sizes, in addition, two of them being gender specific without representing the population.  (Lin et al., 2015; De Vito et al., 1999; GORMLEY et al., 2008; Lovell et al., 2010 and Thomas et al., 1981) ;

Many studies looked into PR after COPD hospital admission. Another meta-analysis reviewed thirteen randomised clinical trials (801 participants). The main focus was to look at the mortality rates after hospital admissions. The analysis didn’t find any statistically significant difference in mortality rate. One of the metrics the analysis was looking at was walking distance, which was collected from eight studies, found a statistically significant difference in exercise capacity, measured by six minutes walking distance test. It was found that there was a 76.89 meters improvement after early PR. Resulting in health-related quality of life improvements. However, the analysis suggested that the evidence is moderate quality and not reflecting a strong evidence to support this difference. (Ryrsø et al., 2018)

It is recommended that individuals complete 150 minutes per week of physical activity with an energy expenditure of around 1000 kilocalories per week, allowing to combine moderate and vigorous activity. Not challenging the body by exercising below a threshold or minimum intensity will not result in VO2 increase nor improvements in other physiological parameters. It is argued that the evidence which support the recommendation lack consistency in many studies, which lead the author of the guidance to suggest additional randomised clinical trials and meta-analysis to obtain stronger evidence (Garber et al., 2011).

Conclusion:

Collectively, exercise training affects the body positively in COPD patients. Respiratory and muscular fitness increases. In addition, to gain the best possible outcome for COPD patients, endurance training seems to be the most beneficial type due to the increase of VO2, as COPD patients struggle with breathing. The effects of exercise types are explored in more detail within the website. Visit Resistance training, Endurance training or Combined training pages to find out more.

Written by: Yousef Rifai (17800407)

Abbreviations:

ATP, Adenosine triphosphate; GOLD, The Global Initiative for Chronic Obstructive Lung Disease; L/min, litre per minute; M, meters; n, number of participants; VO2: maximal oxygen consumption, which is a marker for body efficiency in delivering oxygen to the tissues (Levine, 2008); W, watts; WHO, World Health Organisation.

References:

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