A creative fitness trend in Spain is proving that pop music and exercise can be a powerful combination. A martial arts trainer has gone viral on social media after using a classic Christian Castro song as the core of a high-intensity workout for his students. The idea is simple, playful, and surprisingly effective for burning calories and losing weight in a short period of time.
If you love Christian Castro and also enjoy physical activity, this routine blends nostalgia, rhythm, and movement into one energetic session that feels more like a game than a workout.
© Getty ImagesThe song at the center of this trend is “Azul,” one of Christian Castro’s most recognizable pop hits. The trainer’s rule is straightforward. Every time Christian Castro says the word “azul,” students must perform a burpee. That single instruction transforms a four-minute pop song into a full-body cardio challenge.
What makes "Azul" ideal for this purpose is its structure. The word “azul” is repeated many times throughout the song, creating unpredictable but frequent exercise cues. This keeps participants alert, engaged, and constantly moving.
The song lasts 4 minutes and 21 seconds, which is a perfect time frame for a short but intense workout round. According to counts shared online, Christian Castro says the word “azul” 57 times during the track. That means 57 burpees in just over four minutes.
How This Workout Helps You Lose Weight
Burpees are considered one of the most effective bodyweight exercises. They activate multiple muscle groups at once, including legs, core, chest, arms, and shoulders. They also elevate the heart rate quickly, making them excellent for calorie burning and cardiovascular fitness.
Fitness sources estimate that a single burpee burns around 0.5 calories, depending on body weight and intensity. That means completing all 57 burpees during the song could burn roughly 28 to 30 calories in one round. If you repeat the song four times, you could reach more than 100 burpees and burn close to 50 calories or more in under 20 minutes.
© iStockThe trainer in Spain also suggests switching exercises depending on fitness level. Instead of burpees, participants can do push-ups, squats, or a mix of movements. This flexibility makes the routine accessible to beginners while still challenging for advanced athletes.
A Simple Home Workout You Can Try Today
One reason this trend has gone viral is how easy it is to replicate. You do not need special equipment or a gym membership. All you need is space, a speaker, and the song “Azul.”
You can structure your session like this. Play the song once and do burpees every time you hear the word “azul.” Rest for one minute. Play it again and switch to squats. On the third round, do push-ups. On the fourth round, combine exercises or return to burpees if your energy allows.
© Getty Images/Cavan Images RFIn less than 20 minutes, you will complete a fun, music-driven workout that targets strength, endurance, and calorie burn.
When Christian Castro Released ‘Azul’
“Azul” was released in 2001 as part of Christian Castro’s studio album of the same name. The song quickly became a major hit and remains one of his most beloved tracks. Its catchy melody, pop sound, and emotional intensity helped it define an era for many fans across Latin America and Spain.
The song’s theme revolves around love and emotion, using the color blue as a symbol of intensity and feeling. Years later, that same repetition and emotional delivery are giving the song a second life in fitness studios and social media feeds.
