Purpose: In this case report, we examined the effects of an aquatic exercise program on respiratory and knee extensor muscle strength in a 72-year-old female patient with knee osteoarthritis and reduced respiratory muscle strength. Decreased respiratory muscle strength is linked to a diminished coughing capacity, which increases the risk of atelectasis and pneumonia, particularly in older individuals with limited physical activity. This study reports the effects of aquatic exercise on a patient with knee osteoarthritis and decreased respiratory muscle strength.

  Methods: The patient participated in an 8-week aquatic exercise regimen, including walking in water at a depth above the fourth intercostal level, to achieve 60% of the predicted maximum heart rate. The pre- and post-intervention measurements included knee extension strength, grip strength, respiratory muscle pressure, vital capacity, and 6-meter walking speed.

  Results: Improvements in expiratory muscle strength, bilateral knee extension strength, and walking speed were observed after the intervention.

  Conclusions: Buoyancy of the aquatic environment minimizes joint load, whereas water viscosity provides resistance and enhances muscle strength without adverse effects. The increase in expiratory muscle strength suggests a potential training effect on the respiratory muscles owing to hydrostatic pressure resistance. These findings underscore the value of aquatic exercise in patients with musculoskeletal limitations and suggest its utility in maintaining respiratory function in older populations. Future research should explore long-term effects and include broader sample sizes to validate these outcomes.

  Spa therapy in Misasa (Tottori Prefecture, Japan) is renowned worldwide for its radon therapy (particularly high-concentration radon hot-air bath therapy) along with mine therapy in Bad Gastein (Austria) and Montana (USA). Radon therapy is indicated for diseases related to the respiratory system, pain, digestive disorders, chronic degeneration, and aging caused by reactive oxygen species; however, most of these indications are based on empirical prescriptions. To address this, the authors have been conducting basic research to experimentally and mathematically identify significant radon and its progeny exposure pathways and their related behaviors in the body. The aim is to quantitatively evaluate the relationship between the biological reactions caused by radon inhalation and the absorbed doses in tissues and organs, and to elucidate new mechanisms related to these indications. Therefore, the mechanisms are being elucidated in terms of a series of moderate physiological stimuli caused by small amounts of oxidative stress induced by radon inhalation. Specifically, radon inhalation enhances antioxidant, immune regulation, and damage-repair functions; promotes anti-inflammation, hormone secretion, and circulatory metabolism; and induces apoptosis and heat shock proteins. New indications have been suggested, including inflammatory and neuropathic pain, inflammatory edema, gastric mucosal damage, ulcerative colitis, hyperuricemia, type 1 diabetes, liver and kidney damage, transient cerebral ischemia, and depression. Furthermore, combining radon therapy with antioxidants and therapeutic agents has been suggested to synergistically enhance the disease-suppressing effects of the therapy. Further clinical verification of the combined effects of radon therapy and conventional treatments is required to reduce the dosage of drugs that cause severe side effects.