"Altitude training" is a fitness term that refers to exercise done in high-altitude environments to improve endurance and increase lung capacity. Synonyms for altitude training include high-altitude training, hypoxic training, and mountain training. Hypoxic training involves breathing in reduced oxygen levels to simulate the effects of high altitudes on the body. Mountain training is similar to altitude training but typically involves training in mountainous areas, which can offer similar benefits. High-altitude training is a broad term that encompasses all types of training done at high elevations. Regardless of the terminology used, altitude training techniques can be highly effective for improving endurance and overall fitness levels.