It seems to be that this is a misleading title. First of all, we can trust this source as according to mediabiasfactcheck.com, they are high on the factual reporting scale which is the second highest level. The same site states that they have high credibility when it comes to reporting facts. The article frequently mentions a study from the University of Colorado - Boulder, which is a reputable university, especially when it comes to the effect of THC on the body. The conclusion that the article came to was that only 29% of the users in the study reported that they felt like cannabis use before workout. The article also states that users found it much harder to run because of an increase in heartrate, which according to the head of the Boulder study, athletes run 31 seconds per mile slower, which might not seem like a lot but in a race can make a massive difference. Another interesting point is that the study did say that it lead to an increase in motivation in the workout, which for some people who have trouble motivating might be helpful.