When you think of the concept of tempo the first thing that probably comes to mind is music. However, tempo is not just important in music, it can be an excellent tool to incorporate into your strength training workout. In very simple terms, tempo means the number of seconds it takes to complete the lowering, lifting and pause phase of a single repetition of an exercise. In an exercise routine, tempo is denoted by a four digit number, for example, 4010 or 30X0. To explain this in more detail, let's separate out the numbers:
4 - The eccentric (lowering) portion of the lift
0 - The pause at the midpoint
1 - The concentric (lifting) portion
0 - The pause at the top (before starting the rep again)
Using a slower tempo increases the time the muscle is under tension, meaning the time a muscle is under 'stress.' The 'X' on the other hand, refers to completing the phase explosively such as in Olympic lifting and can be great for fast twitch muscle development.
There are many benefits of using tempo in your workouts. Firstly, using a slow tempo allows you to focus on technique and form by giving you more awareness and control of your movements. This in turn can also help prevent injuries as you are increasing the stress on the muscles but reducing the impact on the joints. This can be great for newer trainees as slower movements build strength without compromising technique from lifting too-heavy loads.
Using a slow tempo will also assist in developing strength at a faster rate. Increasing time under tension will recruit more muscle fibres. This in turn boosts metabolism - not just because you are making your body work extra hard but because the tiny tears in the muscle means your body is expending more calories to repair these even after the workout is finished.
There is also great benefit in including isometric pauses within your tempos, especially for your upper back work. Pausing for 1 second at the midpoint means you can't use momentum with the movement which therefore increases strength gains. Isometric pauses also recruit higher threshold motor units, giving you a greater neural response and greater strength potential. Some examples of this would be if you are doing a form of row or pull-down, hold the bar to your chest for 1 second before releasing slowly.
If you've reached a plateau in your strength training or just want to mix up your workouts, try playing around with some slower tempos. You will probably find that you will need to drop the weight slightly at first but as long as it's minimal it won't impact your strength gains. In fact, you'll most likely find you will benefit from it.