There are many proponents of interval training in the strength world, one being Michael Boyle, whom a lot of these ideas are derived from. Interval training is basically conditioning work that has alternating periods of work and rest. If you want to be an explosive athlete and stay explosive then you want to limit the amount of slow twitch work you do.
Studies have shown that your muscle fiber can actually change into slow twitch muscle fibers if you do too much steady state cardio. Look at a sprinter versus a cross country runner. A sprinter will be more explosive and will have more muscle than a cross country runner. Interval training can develop both your anaerobic system and your aerobic system. A lot of times you actually develop the aerobic capacity better by doing interval training than just doing steady state conditioning alone. As long as your heart rate is above 120 bpm you are getting some aerobic training.
On top of that you can get your conditioning done in a short period of time versus doing an hour of road work. That isn't to say that steady state conditioning is entirely bad; it greatly can help with recovery and for some people, who aren't in shape, intervals may be too intense. It is also important to reinforce that doing intervals stimulates the anaerobic system as well as the aerobic system.
There's a bunch of different methods available to conduct interval training. You'd like to pick a method that is a full body workout that can easily get your heart rate up and one that you can do at max speed/intensity. Here is a list of methods that I've used in the past that have been adequate: Shuttle Runs, Tempo Runs, Stationary Bike, Versa Climber, and Rowing Machines. Shuttle Runs are my favorite because they don't require any special equipment and you can do it pretty much anywhere. Shuttle Runs are also more difficult than doing straight away sprints but must be carefully programmed when training non-athletes.
You'll have to play around with your work to rest ratio but one ratio that Michael Boyle uses a lot is 1 work to 3 rest. The longer you go, the closer to 1:1 of a ratio you can go. For example you might do 100 yard shuttle at ~15 seconds. Your rest period will be 45 seconds.
Depending on your conditioning level, you'll need to then pick the number of sets. 6-8 Sets is generally a good guide for shorter work periods. For longer work periods you may need less sets. Manage your volume like how you would manage your weight training. You can progressively add sets to your cycle and have cycles with lower sets. You can also lower your rest times. This is something you'll have to play with and manage your athletes total work load.
Another point of consideration will be that for your first set, an athlete may not need as much rest. Therefore, you first set might have 15 sec work and 35 sec rest. 2nd set have 15 sec work and 40 sec rest. 3rd set 15 sec work and 45 sec rest. And the remaining sets all have 45 sec rest. Longer work periods won't be done to maximum intensity (you can't sprint for a minute) and won't require a larger rest to work ratio.
For example: a 200 meter tempo run may take ~1 minute. Your rest period might be 1 minute. Also taking into consideration that for your first set you may not need as much rest, so it may be only 50 sec rest. Another way to program your training is to rest until your heart rate drops down to 120 bpm and then going again.
This is a more individualized way of maximizing your training but much harder to conduct with larger groups. For this example you would do your maximal work for 15 seconds then rest until you have recovered to 120 bpm. After your recovery you would do another set. This is a preferred way of training if you have a heart rate monitor. The heart rate monitor that I use is a Polar RS100. You can find it for under $100 online and it is well built.
After doing interval training it is important to get in your nutrition. Post workout, you need a sport supplement like ATH's Muscle Recovery that has a ratio of 3 carbohydrates to 1 protein. You want a good mix of carbohydrates that has a fast and slow digesting rate that will restore your muscle glycogen. A common mistake that athletes make is to only take in protein post workout. Your actual protein requirement will be less than the carbohydrates you need to turn your body from a catabolic state (breakdown state) into a muscle building and recovery state (anabolic state). For a complete recovery shake that is proven to work-- order ATH's Recovery.