# Whole-Body Cryostimulation: A Rehabilitation Booster in Post-COVID Patients? A Case Series
## 1 Introduction  
Coronavirus disease (COVID-19) is an infectious disease caused by the SARS-CoV-2 virus, and the globally confirmed case count of COVID-19 surpassed 290 million in January 2022 (World Health Organization, n.d.). Despite pulmonary impairments being the most prevalent, extra-pulmonary manifestations of COVID-19 are abundant, involving psychosocial, cardiovascular, hematologic, renal, gastrointestinal, and central nervous system symptoms, as well as post-intensive care syndrome. COVID-19 causes a strong pro-inflammatory cytokine storm, which can often persist also in the subacute phase and can lead to muscular complications such as critical illness myopathy (CIM) [1], and acute sarcopenia [2]. The long-term implications of the 'post-COVID-19 condition' (PCC) [3], defined as persistent symptoms usually occurring 3 months from the onset in individuals with a past confirmed or probable SARS-CoV-2 infection, persisting for at least 2 months, and which cannot be explained by an alternative diagnosis, still remain to be fully uncovered [4; 5; 6; 7]. The most frequently reported symptoms are musculoskeletal (fatigue and muscle aches) and psychological (concentration and memory deficit, depression, and anxiety), and also includedyspnea, persistent cough, fever, and loss of smell or taste [3; 4; 6; 8]. More than 30% of individuals affected by COVID-19, including asymptomatic cases, and approximately 80% of patients hospitalized for COVID-19 have PCC symptoms [4; 9]. SARS-CoV-2 patients require intensive multidisciplinary rehabilitation, aimed at restoring independence in basic daily activities [10]. In contrast to other self-limiting symptoms (e.g., anosmia) [11], fatigue and cognitive impairment appear to endure or even worsen in susceptible individuals [12]. Rehabilitation guidelines for PCC patients have been released by the World Health Organization, Cochrane Rehabilitation launched REH-COVER, and there are continuous updates in the scientific community on rehabilitation best practices for these patients [9; 13; 14]. Physiotherapy and resistance training integrated with nutritional interventions, along with reduction in the inflammatory state, is key to regaining independence in PCC patients. Whole-body cryostimulation (WBC) exposes patients to cryogenic temperatures, ranging from \(-110\)\({}^{\circ}\)C to \(-140\)\({}^{\circ}\)C, in an environmentally controlled cabin for 2-3 min. Such stimulus induces pain and inflammatory status reduction in different conditions [15; 16; 17; 18] and induces improvements in depression, anxiety [19], functional status and fatigue [20], and quality of sleep [21]. It is widely used as a recovery technique after physical exercise in elite athletes [22] and the positive effects of 10 serial WBC sessions on PCC patients have been reported 1 month after discontinued treatment [23]. The broader existing evidence of clinical and functional benefits following WBC in musculoskeletal and neurological conditions provides a rationale for prescribing WBC for post-COVID symptoms. To the best of our knowledge, only one study to date has investigated the effects of WBC on post-COVID musculoskeletal and respiratory symptoms [2]. Therefore, the main focus of this case series was to provide preliminary evidence about the role of whole-body cryostimulation (WBC) as an effective adjuvant for the recovery of patients with the post-COVID condition (PCC).