I have seen people wear them for trail running, ultra marathons well the older model of the two that look like Merrils in 2013 about the time the minimal running shoe thing was at it peak, newer model was not out yet. Saw them when working a station at the Black Hills 100 in 2013, a race that is tough due to having many little hills during the whole race on the Centennial trail in the Black Hills a guy in his 50-60 was running in the shoes and they were holding up fine. Also saw the guy in his upper 80's who did the Fargo Marathon as his 2000th marathon and he had on the older model but a white color of the shoes they used to sell though his were near the end as he shoe goo, because he probably just put way more miles on the shoes then one is supposed to on any pair of shoes. The other trail model that Tesla is selling not the minimal model that looks like some version of Salamon shoe, is not great, I have seen reviews stating the upper is stiff and clunky and the midsole is hard. The road model has mixed reviews, the one that looks like an older model of Nike Free or older Adidas Bounce shoe model.