Time Under Tension Training
Time under tension (TUT) is well researched but there are still many skeptics to the agreement that only tension will increase the size of the muscle. The valid argument of TUT is that the amount of time your muscles spend under tension when doing a set is what fires up the muscle fibers.
There are countless studies that can be found online that actually prove that using TUT will get worse results than regular training. The adjustment of tempo study done at University of Sydney discovered a self-regulated tempo produced the best results. Slow TUT workouts showed less strength and muscle gain.
Tempo is a different argument because science has clearly proved that taking 5 seconds to complete a compound movement gets the best results. This tells us that TUT does have something to do with strength gain. The argument can be refined down to a single question.
If you can squat for 10 reps with 100lbs on your back using a 2-0-2 tempo, then your TUT set of 10 reps will probably be around 50% lighter because of the extra effort TUT. The question is, will doing 10 reps on normal tempo get the same benefit as TUT training?
The answer can be found in the basic principal of gaining muscle, which is progressive overload. If we can progressively overload the muscle fibers by lifting a weight 10 times, we will gain muscle. As mentioned above there are many studies to support this.
Bodybuilders know that TUT works because if you have never trained decreasing the tempo to as slow as possible then you should try it. If you do a few sets you will more than likely get delayed onset muscle soreness (DOMS). This tells us it works.
TUT could be 2-0-2 for someone who has never done TUT before. It depends where you are coming from. If you are someone who wants to do TUT with only a barbell because you want to increase the time spent under tension to the maximum, then you should rather add some weight and do faster reps.