In 2023, Förstemann piloted Thomas Ulbricht to a silver medal in the tandem B sprint and a bronze medal in the tandem B kilo at the 2023 UCI Para-cycling Track World Championships in Glasgow.

The German Olympic team used a loophole in the International Cycling Union (UCI) regulations to include Förstemann as an additional member of their 2012 sprint cycling team.

In July 2012, a photograph of Förstemann's legs was widely circulated by the world's media during the 2012 Summer Olympics.

[2] Described as a 'quad off' with Olympic team-mate André Greipel, the photo showed his quad muscles compared with those of the road cyclist.

[3] A circumference of 86 centimetres (34 in) has also been recorded, and the size of his quad muscles has led to him being called "Quadzilla" by some in his sport.