http://www.ncbi.nlm.nih.gov/pubmed/24832974This is a great find. I dug of the whole research article.
The most efficient way to build muscle is to keep intensity up. If you want to mix it up, vary the exercise selection.
Constant Intensity Varied Exercise (CIVI)
The main finding of this article is that using different exercises that are similar in nature increases strength.
Squat Example: Leg Press, High Bar Back Squat, Low Bar Back Squat, Front Squat, Zercher Squat, Belt Squat, etc.
The training constant with CIVI is the intensity. That meaning that each lift need to be preformed with a 85% of 1 Repetition Max with low reps, 1-5 reps.
This "Max Effort Method" is the foundation that the Bulgarian Weightlifters use to dominate Olympic Lifting.
Frequency of Max Effort Varied Exercises
For increasing strength, changing up the Varied Exercise need to be frequently.
How often to a great extent depends on...
This means how long you have been training rather than you real age.
Older More Frequent
Individuals who have been training a long time need to change up the exercise frequently.
Week 1: Leg Press max out.
Week 2: Zercher Squat max out.
Week 3: Front Squat max out.
That could mean every training session.
Younger Less Frequent
Novice lifter who just started training can preform the exercise more frequently.
That meaning that using the same max effort perhaps for three training sessions.
Week 1: Leg Press max out
Week 2: Same as 1.
Week 3: same as 1.
Week 4: This now become Week 1 of a new exercise.
Schoenfeld is one of the best.
By the way, this was on Brad Schoenfeld's facebook just now. He's a great source of good training ideas. https://www.facebook.com/brad.schoenfeld.cscs
THE MECHANISMS OF MUSCLE HYPERTROPHY AND THEIR APPLICATION TO RESISTANCE TRAINING
This looks at the three primary mechanisms that are necessary for hypertrophy, muscle growth.
1) Mechanical Tension: Limit (1 RM) Strength
2) Metabolic Stress: The Bodybuilding Pump.
3) Muscle Damage: Stretching the muscles under a load.
Example: The bottom position of a squat with a barbell load.
Going to Failure
To maximize strength and hypertrophy, at some point, is the key.
Dr. Jacob Wilson stated that means at time pushing/pulling the weight up anyway you can. Screw technique.
Pushing/pulling to failure should NOT be used on ANY competitive lift. Doing so, develops poor technique.
Training to failure should be employed on movement that are similar in nature to the competition lift.
Once you've hit failure, trash the Recyclable Exercise with another similar in nature.
Example: One you have trashed a Front Squat move on to something like a Zercher Squat.