Training intensity is an important parameter, as is almost every parameter. Intensity is often used strictly to refer to the percentage of your one rep maximum (1RM) of a given exercise. For example, if you can bench press 100 kg, and you are working with 80 kg, then the intensity is often said to be 80%. But is this really a good definition?
When I think of just the word intensity, it isn't only the effort at any given moment, but also the overall effort involved. For example, if you just bench press that 80 kg one time, then you clearly did 80% of what you are capable of (theoretically). In that case the 80% number summarizes essentially everything. However, if you use the 80 kg to do three reps, then it is more than 80% of what you are capable of. Looking at some tables of average ability, one should be able to 92% of the 1RM for three reps. So the three reps with 80 kg (80% 1RM) were 87% of what you were capable of (.8/0.92 = 0.869). So now the commonly referred to 'Intensity' in this case is not the whole picture. Yes, it was 80% of the 1RM, but the effort was 87% of the maximum effort when looking at the total work done.
I think that this simple definition of intensity, the percentage of 1RM weight used, is ubiquitous enough that I won't attempt to stray from it. But it is really important to understand that this 'relative effort', the percentage of the maximum effort when including sets and reps, is also crucially important.
In beginner's programs like Starting Strength, every workout is at 3 sets of 5 reps at 100% relative effort. Essentially each workout is more than you have done before, and at maximum effort. However, in many intermediate programs, for example The Texas Method, intensity is varied, but so is the relative effort. Usually when people describe these workouts they only describe the varied intensity. The varied relative effort is what allows for recovery from the high volume (and high relative effort) workouts, and is crucial to the success of the program.
Keep it in mind!
