Background and objectives: The COVID-19 pandemic has become a challenge for health systems and, specifically, to physical therapists obligated to adapt their job and stop face-to-face consultations. In this situation, therapeutic exercise has been implemented in different COVID-19 patients. This study evaluated the feasibility and effectiveness of a novel therapeutic exercise program through telerehabilitation tools in COVID-19 patients with mild to moderate symptomatology in the acute stage. Materials and Methods: A total of 40 subjects were randomized an experimental group, based on muscle conditioning, and in a control group, who did not perform physical activity. Thirty-six subjects, 18 in each group, completed the one-week intervention. We measured the six-minute walking test, multidimensional dyspnoea-12, thirty seconds sit-to-stand test, and Borg Scale. Results: Both groups were comparable at baseline. Statistically significant improvement between groups (p < 0.05) in favor of the experimental group was obtained. No differences between gender were found (p > 0.05). Ninety percent adherence was found in our program. Conclusion: A one-week telerehabilitation program based on muscle toning exercise is effective, safe, and feasible in COVID-19 patients with mild to moderate symptomatology in the acute stage.