A powerful voice
As any musically gifted person would tell you, an aspiring musician must practice and exercise every day. Just as if your talent was a muscle, you must dedicate an hour of practice every day to get better at it. There is no way around it; never skip a day!
So maybe we can assume this person took this advice too literally because he is directly exercising his vocal cords muscles while playing the guitar. The strength one must have to lift their whole body by the neck must be unthinkable. Never mind playing the guitar while still hanging from the pole.