Execute test Using API

I created a cycle, added my test to it and got the "Execution ID" all using API. But when I try to get the Test step Execution IDs so that I can update the statuses of the individual test step. The API just returns an empty array. But when I call the same API after I click the execute button in UI it returns the relevant data. Is there a way to execute the test using API. I don't want to UI every time for this.
Thanks