**8. Practical recommendations of RT for COVID-19 survivors**

The new virus known as COVID-19 had shaken the world violently, and WHO in 2020 established pandemic status against COVID-19. WHO recorded 98 million people infected with 2.2 million deaths. Until now, the world remains vigilant and

continues to fight COVID-19. Even after recovering from COVID-19, many writings and clinicians stated that there were many functional and even psychological declines complained by survivors. Sequelae felt, such as persistent muscle pain, fatigue even with minimal activity, muscle weakness, and frequent choking, the point is that they feel that their fitness status has deteriorated when compared to before getting COVID-19 [70].

This general functional deterioration is likely due to muscle atrophy resulting from immobilization during COVID-19 infection, as well as from muscle necrosis. This general functional deterioration is likely due to muscle atrophy resulting from immobilization during COVID-19 infection, as well as from muscle necrosis. Activation of the virus causes oxidative stress that induces overproduction of proinflammatory cytokines, resulting in corrosive cells damaging the myocyte. This damage will be more detrimental to the elderly population [71–73]. This is understandable because physiologically, people above 50 years will experience decrements of muscle mass 5–10% of the existing muscle mass. This decrease in muscle mass will result in the decrease in the functional capacity of the survivors. It is also aggravated by the disruption or difficulty of sleeping due to COVID-19. It is reported that this functional decline will result in depression. This condition will further reduce capacity of the immune system [74, 75].

Could exercise be used as a mean to restore physical functionality and reduce the level of depression in COVID-19 survivors? Deschenes MR [76] stated that exercise can improve morphological adaptations, such as increasing the amount of protein responsible for muscle contractiles and increasing the number of mitochondria [76]. Exercise is also believed to increase the immune system when done with a trusted, staged and sustainable dose.

A systematic review uploaded in 2022 involved research from November 2020 to January 2021, examining exercises given to 286 subject survivors of COVID-19 aged 20 to 84 years. In this study, survivors were trained in AE and RT. The intervention was AE (such as stationary bikes, walking, steps, and treadmill running), carried with low intensity (40–60%) and limited to 30 minutes. Meanwhile, RT was carried out with an average intensity of 50–70% 1xRM, 2 to 3 sets, with an average of 8–12 reps. Pre- and post-exercise evaluations were carried out by assessing the outcome of isokinetic strength, isometric strength, maximal strength, functional capacity, 6MWT, TUG, and strength grip. Exercises were performed for 10 to 12 weeks. Interventions targeted the lower and upper body [71]. Subjective feelings must also be maintained so that fatigue does not occur, which will then reduce the immune system [77]. There needs to be a restriction on subjective feelings limited to a scale of 4–6 out of 10 on the Modified Borg scale. All studies conducted showed better performance and decreased anxiety levels, which aimed certainly to improve the quality of life [70].

Exercise intensity, volume (set and reps) of RT, as well as duration must be carefully observed, so that the prescription of exercise is based on the initial value of functional performance. Some studies show that high-intensity exercise for about 1.5 hours per session is not recommended, because fatigue will occur and lead to decrease in the immune system [78–80]. Keep in mind that COVID-19 is closely related to the immune system, so the physical medicine and rehabilitation team must remain aware of possibility of decline in the immune system induced by exercise. Betschart et al. [81] shared their experience and noted that three patients were unable to continue their exercise therapy due to repeated bouts of the same infection [81]. Davis et al. in 1997 conducted a study on the effects of physical exercise on susceptibility to respiratory infection by using a murine model. They gave three different

#### *Resistance Training is Medicine: Stay Active and Reap the Reward, Live in your Life! DOI: http://dx.doi.org/10.5772/intechopen.109973*

treatments: no exercise, moderate short-term exercise (30 minutes), and prolonged exercise to voluntary fatigue (2.5–3.5 h). It turned out that the results of exercise that are too long will cause fatigue that can trigger a higher mortality rate (41%) compared to groups with no exercise and moderate short-term exercise. Deaths in a group with no exercise reached 19%, while those who did moderate short-term exercise were only 9% [82]. According to the analysis carried out by Siedlik et al. in 2016 [83], heavy and longer exercise (more than 1 hour) can induce a suppressive effect on lymphocyte proliferative responses, with moderate strength statistically analyzed [83]. Some authors, such as Udina et al. [84], stated that short training period of 10 days has shown significant physical performance progress. Survivors do RT exercises: 30–80% 1xRM and limiting subjective feelings 3 to 5 of the modified Borgs scale [84]. Likewise, Herman et al. [85] reported there was no death case or hospitalization case in doing AE with moderate intensity, followed by 20 reps of RT exercises [85].

From these researchers' experiences, it can be concluded that COVID-19 survivors can carry out the combined exercise of AE and RT with safe composition. The prescription consists of AE: 5 to 30 minutes with low to moderate intensity, plus RT: 1–2 sets, 8–10 reps at 30–80% 1xRM. This prescription is also proven to increase muscle mass, muscle strength, reduce tightness when doing activities, reduce fatigue during activities, increase independence and ultimately improve quality of life. We have to stay alert and remain responsible for supervising every exercise. These studies still have shortcomings, such as not including the severity level of COVID-19.
