Vegans perform physically equal to omnivores, or better, according to science.

For everyone doing, or planning to do routine exercise and at the same worrying about not getting enough protein for achieving the workout results they are after, e.g muscle building, maintenance and endurance, there is now “scientifically” proven evidence that a vegan diet is equally good to a meat eaters diet in regards to performance. 

The researchers compiled results from 7 randomized studies and one cross sectional study who all evaluated difference in physical performance in people consuming a vegan and non-vegan diets. No significant difference was identified in between the groups. 

Read more here , http://europepmc.org/abstract/med/26568522

The researchers go on to explain that many athletes nowadays choose a vegan diet for health reasons , but are worried about their nutritional intake profile in regards to their performance. 

Personally, as an ex professional track athlete, I have actually felt stronger and with more endurance, in respect to my training load, from when I was sticking to a omnivorous non-organic diet. 

And as often is the case with studies, further studies need to be conducted.