Experienced the 'What the Hell Effect'

First let me explain what I know about the 'What the Hell Effect' . I read about this effect in a kettlebell book by Pavel Tsatsouline (great book btw). It explained that a control group trained for a contest of pullups, standing broad jumps, 100 m sprint and a 1 k run. The other group trained with kettlebells.
Despite not practicing any of the intended tests the kettlebell group was better in all of the tests - the 'What the Hell Effect'.

A little background on me: I had surgery in December and could not do any exercise (with the exception of walking) for almost 8 weeks. I have only been working out with kettlebells for 6-7 weeks (never used a kettlebell before this time) and started working out with very light kettlebells (I am now using 20 & 25 pound kettlebells). I am almost 52 years old.

I worked out with kettlebells on Tues., Wed. & Thurs. this week. I decided to do something different today and chose a workout dvd that usually gets my heart rate way up and was a great workout for me. I have not done this workout in 4 weeks (I have been doing kettlebell workouts and joint mobility exercises exclusively for 4 weeks). Today the dvd got me sweaty, but didn't get my heart rate up. The instructor on the video was sucking air and I'm thinking, "you really need a kettlebell". What the Hell? I loved it.