Daily Oxygen O3 Treatment Reduces Muscular Fatigue and Improves Cardiac Performance in Rats Subjected to Prolonged High Intensity Physical Exercise

Background

Prolonged, high-intensity exercise places significant strain on the body. It generates large amounts of reactive oxygen species, depletes the muscles' antioxidant defences, and can temporarily impair how well the heart pumps blood. Researchers have long looked for ways to protect athletes and heavily exercising animals from this oxidative damage and the muscular fatigue that comes with it. One area of interest is whether a controlled, low-dose oxygen/ozone (O2/O3) mixture - already used therapeutically for its effects on blood flow and oxidative signalling - could reduce this exercise-induced damage and support cardiac performance. This study set out to test that question directly in an animal model of sustained, intense endurance training.

Study design

Researchers used 40 male Sprague-Dawley rats, split into eight groups of five. All animals followed a progressive treadmill running programme, five days a week for eleven weeks, building up to 75 minutes per session at 25 metres per minute on a 15% incline - equivalent to roughly 70% of each rat's maximum oxygen consumption. Starting in week two, for five weeks, most groups also received a daily intraperitoneal (injected into the abdominal cavity) dose of an oxygen/ozone mixture one hour before exercise, at one of three doses: 100, 150 or 300 micrograms per kilogram. Control groups received oxygen alone. The researchers then measured how far each rat could run, along with cardiac function using echocardiography (ejection fraction, fractional shortening and diastolic function), blood pressure and heart rate, left ventricular mass, a combined measure of heart performance called the myocardial performance index, markers of antioxidant enzyme activity (Mn-SOD and GPx1) and nitric oxide-related enzyme expression (eNOS), markers of tissue damage (LDH, CPK and troponin I), and the degree of fibrosis (scarring) in heart tissue.

Findings

Rats given the oxygen/ozone mixture covered progressively greater running distances than the oxygen-only control groups, with the largest gain - a 34.5% increase - seen at the highest dose (300 micrograms per kilogram). The ozone-treated rats also showed lower mean arterial blood pressure (down 13%) and heart rate (down 6%), a 49% reduction in left ventricular mass, and less cardiac fibrosis compared with controls. Markers of tissue damage (LDH, CPK and troponin I) were lower in the treated groups, while antioxidant enzyme activity (Mn-SOD and GPx1) and eNOS expression rose in a dose-dependent way - meaning the effect became stronger as the ozone dose increased. Taken together, the results point to reduced oxidative stress and improved nitric oxide-related signalling in both the gastrocnemius (calf) muscle and the heart of the ozone-treated animals.

What the authors concluded

The authors concluded that daily intraperitoneal ozone treatment reduced muscular fatigue and improved cardiac performance in rats subjected to prolonged, high-intensity exercise. They attributed this to improved nitric oxide bioavailability and a reduction in oxidative stress within the gastrocnemius muscle and the heart.

Limitations of this study

This is a preclinical animal study, conducted exclusively in male Sprague-Dawley rats using intraperitoneal injection - a route, species and dosing schedule that differs from how ozone therapy is typically administered to people (for example, major autohaemotherapy or rectal insufflation). The exercise protocol was standardised and relatively short (five weeks of treatment within an eleven-week training programme), and group sizes were small (five animals per group). Findings from an animal exercise model cannot be assumed to translate directly to human athletes or patients, and no human clinical trial data are cited here to confirm these effects in people. This should be read as early mechanistic and preclinical evidence rather than proof of a clinical benefit, and it does not establish ozone therapy as a treatment for cardiac or muscular conditions in humans.