Aerobic training

Aerobic training includes long-term rhythmic exercises in which the body’s main muscle groups participate under adequate oxygen supply conditions. Aerobic training improves patients’ endurance and heart and lung function. There are many kinds of aerobic training, such as walking, jogging, cycling, aerobics, and traditional Chinese exercises such as Tai Chi. Aerobic training consists of both continuous and interval training. Interval training reaches the maximum intensity through a series of short, high-intensity training periods regularly interspersed with low-intensity training and rest. For example, patients can start at 80–100% WRpeak for 20 seconds. They then rest for 40 seconds and repeat for three to four cycles to make the total exercise time roughly equivalent to continuous exercise. The power can be increased by an additional 5–10% when patients can tolerate that intensity. Interval exercise can achieve the same exercise effect as continuous exercise and the subjective discomfort caused by interval exercise is tolerable (5,22). Clinicians often recommend interval exercise if patients’ FEV1 <40% Pred,

WRpeak <60%, SpO₂ <85%, steady-state power test for less than 10 minutes, and suffer difficulty breathing during exercise, which can be used as a reference in clinical research (21).

Exercise training can be conducted outdoors or indoors with fixed-power bicycles, treadmills, and other equipment. In upper limb power bicycle training, an arm dynamometer is fixed at the level of the patient's shoulder, and patients turn a crank with both arms to perform a bicycle-like movement. In lower-limb power bike training, the seat height should be adjusted and maintained at the thigh level. Patients should keep their shoulders back, stomach in, jaw slightly closed, and eyes facing forward, body in a neutral position, and hip joints stable during training. They should start with 5–10 minutes of low-intensity exercise, then 20–30 minutes of designated-intensity exercise, and finally 5–10 minutes of low-resistance and slow-speed exercise to cool down. In this training, the exercise rehabilitation intensity can be regulated by changing the speed or resistance (23).

Stair climbing is also a form of aerobic training that can be conducted with stairways or simulated stairs. Climbing stairs is also a daily functional activity that is more specific for patients who demand more daily activities. Before training, a complete evaluation of lower limb joint function is necessary, especially the knee joints. This training may increase the likelihood of joint and muscle pain, so it should be avoided if patients have severe lower joint disorders. In addition, when stair climbing is a training method, it is also necessary to determine the exercise rehabilitation intensity based on cardiopulmonary exercise rehabilitation assessment and monitor fatigue and the degree of dyspnea during training to control the intensity.