30s HARD, 2min sub Threshold, 30s HARD (Training Session Explained)

Nick and Luke breakdown a session sent through by a podcast listener, repeats of a short hard effort followed by a sub threshold block, back into a 30s burst. Is this an effective session or what could be changed to get more out of it? Plus when might you use this type of session in your training? For more free resources about improving endurance performance, sign up to our email list here: http://go.metsperformance.com.au/free-mets-mastermind