Commonwealth Games marathon medallist Robbie Simpson fears some athletes might be put off trying to reach next year's Tokyo Olympics because of the new qualifying standards.
The IAAF have introduced new qualification times for competitors.
In Simpson's event, the men's marathon, the target time has been set at 2:11:30 - seven-and-a-half minutes quicker than the standard for Rio 2016.
"There might be fewer people who are tempted to go for it," said Simpson.
"And you might just have three or four really good guys, and then maybe not the 10 guys who were in a big group potentially going for the time.
"I think it might put some people off right from the start. It is a bit of a shame because if you come from a smaller country, maybe it is a slightly lower standard that is achievable.
"It might be too big a jump up, although having said that I know there are definitely three guys in Britain who can run sub 2:11:30 right now, so it might not actually change the top three."
Athletes will also be able to qualify through the new world rankings system.
Simpson, 27, won Commonwealth Games bronze for Scotland by finishing third in a race which also saw another Scot, Callum Hawkins, collapse with heat exhaustion while leading the Gold Coast race.
The competitors at autumn's World Championships in Doha will also have to contend with hot conditions, while concerns have been raised about extreme heat in Tokyo next summer.
"I was one of the slowest ones in the field [at Gold Coast], but I ended up getting a medal," added Simpson, who is hoping to secure his qualification time for the World Championships at next month's London Marathon.
"If it is going to be really hot, it is just a fact that you will run slower. It is really going to be an unpredictable race and that is why I think maybe it is a mistake to make the qualification time so much harder."