3.2 Study characteristics
The characteristics of the 24 studies are summarized in Table 1. (a) Study characteristics: A total of 7 interventions are endurance training; endurance and respiratory training; endurance, resistance and respiratory training; endurance and strength training; respiratory and strength training; respiratory training; interval training. A single training modality included 14 studies [15,17,18,21,23,25,26,28,29, 31-33,36,37] of endurance training, 2 studies [27,35] of interval training, and 1 study [24] of respiratory muscle training; (b) The treatment time of the study is different, ranging from the time of up to 4-52 weeks. Most frequent timings to begin intervention were 12 W (n=9) [16,18,23,25,27,29,33,34,37], 6 W(n=6) [15,21,22,28,32,36]; (c) Most of the studies treatments frequency are different, from 1 to 6 times per week. Most of the study treatment frequency were 3 times per week (n=12) [14-17,22, 25-27,29,32,36,37]. 2 times per week (n=6) [20,21,23,30,31,34]. (d) Most studies were conducted in hospital settings (n=7) [14,16-18,23,26,32], followed by patients’ home (n=2) [19,33], school (n=2) [24,35]. Some studies did not mention the specific location of children’s exercise (Table.1).