Oregan Circuits were derived to meet to dual goals of S&C and also maintain Aerobic ability
The term tempo is used a lot in training and really needs to be understood, tempo actually means time or rhythm and in running terms means nothing. So what do we base tempo on?
For the endurance athlete they should base their calculation on their 5k pace, where you take % of the=at pace and assign it to a distance, for instance you would run up to 30 mins at 95% of your 5k pace, 90% up to 45 mins and 85% up to an hour. You now have a logical basis for tempo training, you can gain a lot from running at paces based on 5k pace, you don't have to be running at your limit to get improvement in ability.