The “what” is simply the detail of the workout to be performed…the paces, heart rates, effort levels, duration, rest intervals etc. There are unlimited combinations of these variables that can be remixed into workouts. Through experience and experiment we know the “Whats” that produce the best results for effort expended and stimulate the most important improvements in function and performance. Even a simple run, like a shakeout jog the morning after a hard or long effort should have specific parameters for you to follow to get the most benefit from the session. In this example, the specifics might be: HR <70% max, duration 30-40 min, and soft surface.
The coach’s job is to be as precise about the “What” as possible, to help you perform your sessions as intended every time for best benefit. If a workout contains vague instructions, such as “60 min, comfortable pace” you may need to ask for more precision. If your workout contains a well defined “What” make sure you understand the details and perform the workout correctly!
Even the best individual workouts are much less effective if thrown together into a schedule at random. For each training session there is a correct “When”…the best time to perform the training for maximum benefit. The When for a session needs to be established relative to your overall season, the proximity to your upcoming goal races, and what workouts come before and after it.
In a well-designed training week, the When of the sessions will be logical and provide a good balance of recovery and work. Juggling sessions or scrambling to make up missed mileage can derail the most carefully constructed rest/recovery pattern.
In a well-designed training cycle (i.e., months) there should be a rationale for the When of each major training sessions relative to the goal race.
You and your coach should be combining the What and When of each session through the training cycle to bring you to your individual peak fitness on race day. Realize that if you are performing exactly the same sessions during your marathon prep as your training partners getting ready for 10k races someone is not getting the best What/When combination!
Each training session should also have a clearly understood “Why”. The Why is the physiological changes that the workout is hoping to stimulate and how these will help your race performance.
Our shakeout jog, for example, is performed in order to increase blood flow through the overworked muscles and help clear out waste products, the low HR prescription ensures that the run is at a completely relaxed effort to keep cortisol levels low and lactate levels at baseline, the soft surface is suggested to compensate for the reduced shock absorbing ability of stiff leg muscles and thereby reduce risk of overuse injury.
Understanding the Why of your sessions will help you as an athlete make sure that the program you are following is a well-designed and intelligent one. Knowing the purpose of a session also makes it easier to stick to a workout as planned both when it's challenging and when purposely gentle.
This understanding of and belief in what you are doing will make you mentally stronger and more confident in your preparation.
There is also power of intention, in that having very clear, well-understood objectives makes them more likely to be achieved.
Ask your coach (or yourself if designing your own program) the What, When and Why of any of your training sessions for which this is unclear. If you get answers like: “Don’t over think it”, or “Because it will make you tougher”, or “Because it’s hard”, or “Because we did it in college” it should be a red flag.
Random training produces random results.