If you plan to peak for a 70.3 or full Ironman, you may be better off using an hourglass-shaped approach. Begin with a solid period of base prep in order to develop aerobically, strengthen connective tissue, and enhance muscular endurance. Then, enter the slender center of the hourglass by enjoying a month or two filled with short and spicy training and racing that will lift threshold and VO2 speeds while improving efficiency and economy. Then, with about two months to go before your final A race, ideally just after your mid-season break, lengthen your key training sessions to match the specific demands of your goal race. Aim to simulate race pace and intensity, which is best done using objective training measures such as heart rate and/or power.