Slow tempo strength training involves performing a compound lift (squat, pushup, row, etc.) at a 202 tempo. This means you'll take two seconds to execute the eccentric portion of the movement, and then two seconds on the concentric portion of the lift, too. There will also be no pause at the top or bottom.

So, for a pushup, you'd take two seconds to go down, and then immediately transition into the concentric and take two seconds to go back up. See the video on the right to see what I mean (or, you can view it HERE).

What does it do

Increases the cross-sectional area (hypertrophy) of the slow twitch fibers.
Improves oxygen utilization of the working muscles (both fast twitch and slow twitch).
Improves static strength (think grappling, wrestling, etc.).

How to do it

Each rep should be roughly 4 seconds in duration, with no pause at the top or bottom of the movement. Teaching someone to go up slowly can be very difficult (especially as they begin to fatigue), so be mindful of this.
Perform for 40-60 seconds (so about 10-15 repetitions) and your rest period should match the duration of the working set.
Perform for 3-5 sets, which constitutes a series. Perform 1-3 series per workout, with 5-8 minutes of active rest between series.
Constant breathing throughout.

When to do it

At the beginning of a training plan (or at the start of the off-season after you've recovered appropriately).
During a "mini block" in a training plan in order to maintain the qualities you worked so hard to achieve during the first (larger) block of training.

Slow twitch fiber hypertrophy can be a very controversial topic among strength coaches. After all, why would you want to hypertrophy the slow twitch fibers?!

Well, you can utilize oxygen better for one thing, as the slow twitch fibers have the highest capacity for aerobic energy production. When we oxidize lactate - a byproduct of our glycolytic energy metabolism - roughly 80% of that lactate is metabolized in the slow twitch fibers. The larger our slow twitch fibers are, the more lactate we can oxidize (thus allowing us to generate more ATP to improve aerobic/anaerobic endurance).

And, no, your athletes won't lose explosive power and strength if you include slow tempo strength training. As long as you adjust the volume/intensity appropriately, and continue to include the bread and butter strength/power lifts, you have no need to fear them losing power and speed.

-Steve