## 3 Results and Discussion
### Physical Activity  
5.1 What Is the Best Strategy in the Rehabilitation of the COPD Patient, Associated with Nutritional Therapy?  
**Recommendation 19**.: _GARIN recommends pulmonary rehabilitation, combining aerobic and strength training exercises._  
Grade of recommendation A, (100%) Strong consensus.  
**Recommendation 20**.: _GARIN suggests including at least 6-12 weeks of continuous physical training._  
Grade of recommendation GPP, (94%) Strong consensus.  
**Recommendation 21**.: _GARIN suggests the interval modality for patients with severe COPD._  
Grade of recommendation B, (93%) Strong consensus.  
Comment:  
Pulmonary rehabilitation has established itself as one of the key strategies in the management of COPD patients. Pulmonary rehabilitation programs include physical exercise as an essential component of rehabilitation, in addition to other interventions such as education, dietary advice, and psychological support. Studies have shown that a comprehensive and intensive pulmonary rehabilitation program achieves significant improvements in clinical (dyspnoea, fatigue), body composition, physical capacity (exercise tolerance, muscle strength), and quality of life parameters [37; 56; 126; 104; 115].  
One of the hallmarks of COPD is the progressive decline in physical exercise capacity due to skeletal muscle loss and dysfunction, which is a predictor of morbidity and mortality independent of lung function impairment [15; 32; 56; 60; 104; 113; 126; 127; 128]. The COVID-19 pandemic further exacerbated these effects, significantly reducing physical activity levels and potentially worsening muscle loss and dysfunction [129].  
Muscle training has been widely shown to be effective in improving exercise tolerance, muscle strength, dyspnoea, fatigue, and quality of life [37; 126; 130].  
Studies are currently focusing on identifying the essential components that achieve the best results in the short and long term, including the type and exercise intensity, frequency and duration of sessions, location (center or home), face-to-face supervision or other innovative strategies (tele rehabilitation), individualized or in groups.  
Aerobic or endurance training is the most widely used form of exercise, for which there is the strongest recommendation evidence. A modification of standard aerobic training is interval training, where periods of maximal exertion are regularly alternated with equal periods of rest or lower-intensity exercise. In this way, patients achieve high levels of exertion but with less dyspnoea and fatigue, providing benefits equivalent to those of classical aerobic training [37; 126]. Studies consistently show that interval training is one of the best treatments for the most severe COPD patients [124; 131].  
Muscle strength training has great potential compared with aerobic exercise to increase muscle mass and strength and the advantage of less cardio-respiratory compromise [80; 126; 127; 132].  
Most training programs achieve the best physiological results through a combination of the two types of exercise [126; 115].  
There is no consistent evidence to define the duration of training programs. Although studies of very variable duration (between 4 and 16 weeks) have been proposed [124; 113; 126], most of them consider that substantial benefits can be achieved with a duration between 6 and 12 weeks and with a frequency of 3-4 sessions per week [126; 127; 128; 133; 37; 115].