When most people think of increasing tension, they think about adding more weight. There are several ways to increase tension by changing many training variables. Changing load (i.e., weight), proximity to failure, frequency, exercise selection, range of motion, technical execution of the exercise, and rest periods can all influence the potency of the exercise stimulus achieved with any given number of sets.
3 FACTORS OF MUSCLE HYPERTROPHY. [THE SCIENCE-BACKED PLAN] HOW TO GET BUFF SUMMARY
- Muscle hypertrophy can increase in size (diameter) or increase in length.
- High muscular tension, sufficient time exposure to that tension, and sufficient effort increase muscle growth.
- Repetitions should be completed through a full range of motion
UPDATE ON THE MECHANISMS RELATED TO MUSCLE HYPERTROPHY: 4/14/2022
Research gave an update on mechanisms related to muscle hypertrophy and future research:
- Mechano-transduction (Tension placed on the muscle is “sensed” resulting in a chemical signal to create an anabolic response). High level of evidence to unravel mechanisms of muscle growth.
- Resistance Exercise Acute Increases in Anabolic Hormones (i.e., GH, IGF-1, and Testosterone)- low level of evidence for acute anabolic hormones contributing to muscle hypertrophy.
- Muscle Damage- Low level of evidence that muscle damage contributes to muscle hypertrophy.
- Metabolites- Increased levels of lactate, hydrogen ions, etc.- low level of evidence that metabolic stress contributes to muscle hypertrophy. 
UPDATE 4/19: SUMMARY REVIEW OF MECHANISMS OF MUSCLE HYPERTROPHY RELATED TO HYPERTROPHY VS STRENGTH GAINS
A summary review of the mechanisms of muscle growth :
Load and Intensity:
Heavy and light weight protocols can increase muscle growth equally. Mechanical stress performed to concentric muscular failure, regardless of the weight, results in full muscle fiber activation. Loads between 30 and 90% can increase muscle growth. Heavy weights are needed to maximize strength development.
Types of Contractions:
There is no superiority in emphasizing eccentric contractions over concentric contractions for increasing muscle growth. Both contraction types are equally important for increasing muscle growth.
Number of Repetitions:
The muscle does not have an internal counting mechanism for repetitions. Repetitions can be low with high-intensity exercise (i.e., 5 reps at 80% of a 1-RM) and high with low-intensity exercise (25 reps at 30% of a 1-RM) and increase muscle growth similarly when taken to failure. If sets are taken to complete failure, muscle growth will be similar regardless of repetitions. Various higher repetitions ranges should be utilized to elicit metabolic stress on the muscle.
A wide range of repetitions can be used to elicit muscle hypertrophy between .5 to 8 seconds. The recruitment of full muscle fiber activation when performing sets to failure stimulates muscle hypertrophy rather than repetition duration.
Number of Sets: Increases in sets can increase muscle growth up to a certain point; more sets can decrease muscle growth. Volume has an inverted U response, with sets increasing muscle growth up to a certain point and, after that, diminishing returns.
Rest Periods Between Sets:
Shorter rest periods reduce total training volume. Shorter rest periods reduce muscle tension but increase metabolic stress, which may be a contributing factor to muscle growth. Total volume seems to be the driving factor for muscle growth rather than rest periods between sets when examining the research.
Frequency has little impact on strength or muscle hypertrophy. Training volume is the determining factor. It is recommended that 48 hours of recovery before an exercise is re-trained for recovery and optimal increases in muscle protein synthesis.
Training to Failure:
The lighter the weight, the more important it is to train to failure. Training to muscular failure ensures an effective stimulus has occurred. Heavier weight can be used while stopping short of failure and still result in equal muscle growth as training to failure.
Range of Motion:
A full range of motion should be used for inducing muscle hypertrophy compared to a partial range of motion. A partial range of motion in the lengthened position may be as effective as a full range of motion. People with joint/muscle issues may benefit from a partial range of motion to induce hypertrophy and be used as an effective rehabilitation program.