Cardio Max helped relieve my muscle pain!

Hello everyone. I had quite an experience this evening. I've been suffering from a pulled muscle in my upper back since yesterday. I took a muscle relaxer last night and still no relief , today I also wore a muscle pad on my back for 8 hrs, still no relief. Anyway, got home and did the biggest loser cardio max on a whim. I noticed while I was working out the pain was becoming less and less. Well after a 5min. warm-up, 20min cardio, and 5 min. cool down. NO MORE PAIN ! I feel good now, even feel like I got a burst of extra energy. Well, i'm going to have a snack now and prepare my food for tomorrow.