Hypertrophy Specific Training (HST)

Part 1: Strength Versus Endurance

Hypertrophy specific training (HST) is an approach to strength training that has recently generated a lot of excitement among professional trainers. Strength Training comes in more than one flavor depending on the goal: endurance, size, strength, and power. Hypertrophy specific training aims specifically to build muscle size (hypertrophy). For people who have reached middle age, this means regaining muscle already lost through the aging process, a process known as sarcopenia. Our fear is a becoming feeble, not growing bulky.

Articles by Bryan Haycock on Hypertrophy Specific Training (HST)

Strength and endurance are linked like the two sides of one coin. We train for both strength and endurance not because we want both, but because it's what Bryan Haycock calls the "rational" way to build muscle size. With hypertrophy specific training, we do not neglect either endurance or strength.
  • Low weight with many repetitions requires high endurance
  • Medium weight with medium repetitions stimulates muscle growth
  • High weight with low repetitions strengthens and consolidates the added muscle
Repetition Maximum is a key concept. Your repetition maximum (RM) is the maximum load you can lift a specific number of times. For example, if you can lift 22 pounds 5 times, but not 6 times, your 5RM for that exercise is 22 pounds (10 kg).

The logical connection between strength and endurance can be illustrated as follows:

  • If you can lift 12 pounds (5.5 kg) 15 times, but not 16 times, then your 15RM would be 12 pounds.

  • You should then be able to lift 15.5 pounds (6.5 kg) 10 times, but not 11 times, and your 10RM would be 15.5 pounds.

  • You should be able to lift 17 pounds (7.75 kg) 5 times, but not 6 times. Your 5RM would be 17 pounds.

  • The pattern is now revealed: As the number of repetitions decreases, the weight that can be lifted increases. The weight that you can lift 10 times (your 10RM) is about 20% greater than the weight you can lift 15 times (your 15RM). The 5RM is about 20% greater than the 10RM. Experiments have shown that the 1RM is about 20% greater than the 5RM.

  • You would not try to lift your 1RM for fear of injury, but merely estimate your 1RM as 20% greater than your 5RM. If you can lift 50 pounds five times but not six times, your 5RM is 50 pounds. Adding 20% gives 60 pounds and that is your estimated 1RM, the maximum weight you can lift once but not twice.

Styles of Training

Styles of training can be related to fundamental concepts of modern exercise science based on the systematic relationship between strength and endurance. Endurance is indicated by the number of repetitions of an exercise; strength is indicated by the weight of the load moved. High demand for endurance can be met with smaller loads; high demand for strength can be met with reduced endurance.
  • Low volume training uses few repetitions; high volume uses many repetitions.
  • Low intensity training uses light loads; high intensity uses heavy loads.
  • Combining light loads with high volume builds endurance.
  • Combining medium loads with medium intensity builds muscle.
  • Combining heavy loads with low volume builds strength.

Calculating Loads

RM 15 Reps 10 Reps 5 Reps 1 Rep
Load (lbs)1214.51720
% of 1RM60%73%85%100%
RM 15 Reps 10 Reps 5 Reps 1 Rep
Load (lbs)1214.51720
% of 15RM100%121%142%167%

  • lbs = pounds = 0.45 kg.

  • nRM = Repetition Maximum, the maximum load able to be lifted n number of times.

  • Reps = Repetitions = number of times load is lifted.

  • The first section of the table shows the load as a percentage of the 1RM. If you know your 1RM, you can calculate the other loads.

  • The second section of the table shows the load as a percentage of the 15RM. If you know your 15RM, you can calculate the other loads. Note that 121% means that the 10RM is 21% greater than the 15RM. To simplify the discussion, the preceding text rounded off the load increase to 20%. The other numbers were rounded off too. In practice, rounding off the numbers does not matter. This is not rocket science.

  • Dumbbells and other weights usually progress by amounts of 5 pounds (2.5 kg). To get fractional weights, I add lengths of chain with 2 inch (5 cm) links 0.4 inch (10 cm) thick. The ends of the chain are connected to form loops using carabiners.

  • Loads can also be adjusted by varying the repetitions. For example, 15 repetitions can refer to the range 13 to 17 repetitions. Each repetition is equivalent to varying the weight 2.5%. Two extra repetitions (17) increase the effective load by 5%, from 12 to 12.5 pounds. For the 10RM, the range is 8-12 repetitions. Two extra repetitions (12) increase the effective load by about 7%, 1 pound. For the 5RM, the range is 3-7 repetitions. Two extra repetitions (7) increase the effective load by about 5%, 1 pound. Reducing the number of repetitions effectively decreases the load by the same percentages.

  • By adding short loops of chain and varying the repetitions plus or minus two reps, we can achieve fairly precise adjustment of loads. These adjustments keep challenging the muscles progressively, while avoiding injury.

Points to Remember about Hypertrophy Specific Training

  • With very low loads, high repetitions and no rest periods, weight-training becomes endurance training, like aerobics good for building heart muscle.

  • For building skeletal muscle, loads must become progressively heavier, demanding more and more strength, week after week. Bryan Haycock's Hypertrophy Specific Training approach interrupts this progression with periods of strategic deconditioning to avoid progressing so much that loads become dangerously heavy.

  • Hypertrophy specific training does not neglect endurance, because building endurance protects the joints by toughening cartilage, ligaments and tendons.

  • In theory, a person should lift the maximum every lift. In practice, this is not done because the risk of injury is too great. Injury forces layoffs for recovery, which wastes time. Slow and steady is the fastest way to go. What Bryan Haycock proposes for hypertrophy specific training is that maximum weights are used only on the last day of every mini-cycle. When I am doing two weeks of 15RM's, I work out with weights six days, Monday, Wednesday and Friday of each week. On the sixth day, the weights are the calculated 15RM's—the very maximum that I can lift 15 times. (Usually, I cannot quite reach 15 times, something that confirms the calculation was not too low.)

  • To estimate the weights for the preceding five days I subtract enough from the sixth day to ensure that the increase each session is about 2%. That means the weights for the first day of each mini-cycle are about 13% less than the weights for the sixth and last day. I calculate backwards from the sixth day to get the weight for the first day.


To build muscle we need to link the strength and endurance aspects of our training. The "rational" way to build muscle requires at least three styles of training:
  • Light loads with high volume to build endurance.
  • Medium loads with medium intensity to build size.
  • Heavy loads with low volume to build strength.
Hypertrophy specific training requires a period of strategic deconditioning to avoid loads becoming so heavy they cause risk of injury.

With age we do not fear becoming too big and bulky. We fear becoming feeble from age-related muscle deterioration, losing muscle at the rate of 0.5% per year to age 60 and 1% per year thereafter.

Personal Experience

At the end of January 2006, I completed my first full year of hypertrophy specific training. At age 74, my strength has increased at least 200%. For example, I can lift my own weight five times dipping between parallel bars, something I could not do at age 20. While I do have some slight tendonitis in my right elbow, I have avoided injury, which I attribute to the deconditioning phase of hypertrophy specific training.

Bryan Haycock designed HST for experienced athletes who have reached a seemingly unbreakable plateau in training. My experience shows that even a beginner can benefit from hypertrophy specific training (HST).


Part two in this series about hypertrophy specific training will continue with basic concepts of modern exercise science.