Summary
Objective: To compare the effectiveness of two different exercise-based programs through telerehabilitation in patients with coronavirus disease 2019. Design: Randomized, controlled, parallel, double-blinded, three-arm clinical trial. Setting: Patients' homes through telerehabilitation devices. Subjects: Subjects with coronavirus disease 2019 in the acute phase. Interventions: Subjects were divided into three groups: breathing exercises group, strength exercises group or no treatment/control group. Main measures: We analysed visual analogue scale for fatigue, 6-minute walking test, 30-seconds sit-to-stand test, multidimensional dyspnoea-12 questionnaire and Borg scale at baseline and 14 days later.
Results: From 93 subjects recruited, 88 were enrolled, and 77 patients (mean [SD] age 39.40 [11.71]) completed the 14-days intervention and were included in the analysis: 26 in strength exercises group, 29 in breathing exercises group and 22 in control group. The intergroup analysis shows significant differences between the study groups and control group in all variables (p < 0.05); Borg scale, multidimensional dyspnoea-12 questionnaire (pre-post intervention score: strength exercises group: 7.85 [6.82] - 4.54[4.82], breathing exercises group: 11.04 [6.49] - 5.32 [3.63], control group: 10.27 [6.49] - 10.59[6.58]), visual analogue scale for fatigue, 6-minute walking test and 30-seconds sit-to-stand test (pre-post intervention score: strength exercises group: 12.19 [4.42] - 13.58 [5.37], breathing exercises group: 11.18 [3.42] - 12.79 [4.00], control group: 10.45 [2.15] - 9.86[1.88]). The greatest effect sizes were found in the variables Borg Scale (R2 = 0.548) and multidimensional dyspnoea-12 questionnaire (R2 = 0.475).
Conclusions: Strength exercises group and breathing exercises group obtained significant improvements in fatigue, dyspnoea, perceived effort, and physical state, compared to control group, although the greatest benefits were found for dyspnoea and aerobic capacity in breathing exercises group.

Relevance
Findings could become a start point to implement strength and breathing exercises in COVID-19 patients since effectiveness and security have been demonstrated; both interventions showed clinical improvements, combining both could be of interest. Nonetheless, future research should address the main limitations of the study. Higher sample sizes, adaptability of exercises’ load and volume, and feasibility of telerehabilitation assessments should be deeply studied to confirm our findings. In addition, future research may be directed to clarify if the implementation of programs including both types of exercises is more beneficial for the management of these patients; in addition, investigating the possible correlation in clinical improvements and changes in respiratory pathophysiology could be of interest.
Clinical messages
1.Breathing and strength exercises led to clinical benefits in confined patients with COVID-19.
2.Respiratory exercises showed greater improvements in dyspnoea and aerobic capacity than tonic intervention.
3.Both interventions could be integrated with the management of these patients through telerehabilitation devices.