Tri-Sets For New Muscle Growth

How to Use RIR Autoregulation

Muscle Growth

Tri-Sets For Muscle Growth

Combine three exercises in a row without rest. This is called a tri-set. Why do it? Efficiency. You pack more work into a shorter workout, and you can do it in a way that maximizes muscle growth.

But there's a problem. Selecting the appropriate weight and reps is tough. It can be hard to manage fatigue to accumulate work. Fortunately, a simple autoregulation technique can change all of this: reps in reserve (RIR).

Here's everything you need to know about it.

Ascending Effort Using RIR

Your level of effort determines the effectiveness of your training. No, this isn't a vague sentiment about the importance of trying your best. It's the number of reps you do relative to the number of reps possible within a set, or the number of reps left "in reserve" when you finish the set. (1)

When you do "hard sets," you leave no reps in reserve. When you do "easy sets," you leave plenty of reps in reserve. Keep that in mind when you do these ascending effort tri-sets.

You'll use moderate, high, and very-high efforts in sequence, and you'll know their level of difficulty by using the RIR autoregulation system.

Remember, RIR stands for "reps in reserve." Start with a big lift for these tri-sets, then do two single-joint lifts. After each, you'll leave a certain number of reps in reserve.

These will allow you to progress without going to failure on your tri-sets. So first, take a look at some sample tri-sets that'd work great for those on a push-pull split. Then we'll go over the basic execution of ascending effort tri-sets, their rationale, and the programming that'll make them fiercely effective.

Turn up the volume and watch the videos below.

1 Upper-Body (Push) Ascending Effort Tri-Set


  • Bench Press
  • Incline Pec Flye
  • Skull Crusher

2 Upper-Body (Pull) Ascending Effort Tri-Set


3 Lower-Body (Pull) Ascending Effort Tri-Set


  • Deadlift
  • Glute-Ham Raise (or swap it for a Nordic curl)
  • Good Morning (a safety-squat bar feels great, but any bar works)

4 Lower-Body (Push) Ascending Effort Tri-Set


  • Squat
  • Calf Raise (machine or free-weight)
  • Leg Extension (or Reverse Nordic if you don't have a machine)
  1. Start with a multi-joint exercise, then immediately follow it up with two related isolation or accessory exercises.
  2. For each exercise, select a moderate weight – one you'd typically lift for 8-15 reps in a straight set. Yes, this is a broad range, but because this isn't traditional percentage-based programming, the exact weight you choose is much less important. Since you're using moderate working weights, success is in the level of effort, or more precisely, the number of reps you leave in reserve.
  3. Don't worry about counting completed reps. Focus on movement quality and your perception of exertion. You'll achieve an effective tri-set by autoregulating or "self-determining" an appropriate rep volume based on perceived proximity to failure.

Here's how it works:

  • End the first set when you feel you only have 3 good reps left (3 RIR).
  • End the second set when 2 good reps remain (2 RIR).
  • End the third set with only 1 good rep left in the tank (1 RIR).
  • Rest 2-4 minutes.
  • Repeat the tri-set 2-4 times total.

Ascending effort tri-sets are a great introduction to the RIR method of subjective autoregulation. Powerlifters use this method, but it also makes sense for physique-focused lifters.

Tri-sets allow you to complete a workout in less time or pack more volume into the same number of minutes. (3)

But without rest between exercises, fatigue might interfere with your performance of the second or third exercises. One strategy is to train "non-competing" movements or muscles, which can minimize your need for rest between exercises.

However, if you're a physique-minded lifter, you may be using a push-pull split or body-part split. In this case, you may be doing tri-sets that tax the same movement patterns or muscle groups.

Accumulating fatigue during tri-sets must be considered, especially when similar or synergistic muscles are trained. Fatigue is a temporary and revisable reduction in strength. It's related to chemical and mechanical changes in the muscle (peripheral fatigue) and the reduced ability of the nervous system to stimulate the muscle (central fatigue). Both types of fatigue likely accumulate via intertwined mechanisms during our workouts.

Although this may come as a shock if your focus is to "burn out the muscle," fatigue can be an enemy of hypertrophy training. When it accumulates, the relative sharing of loads changes amongst synergist muscles. That means compensations occur, whether you can sense it or not. You're likely to experience more overt effects, too, like ending sets early and having to reduce the weight.

Altogether, fatigue opens the door for suboptimal training. The target muscles are ultimately robbed of mechanical tension: the primary driver of your gains.

Fatigue is especially pronounced during high-volume workouts, compound exercises, and sets taken to failure. It's largely unavoidable, so it must be managed. For this purpose, autoregulation via things like RIR is extremely useful.

Although technology can help us regulate our programs (devices to measure movement velocity, smartwatches to capture heart rate variability, etc.), the most approachable autoregulation technique requires no gizmos.

"Subjective autoregulation" relies on your perceptions to inform program modifications. That's where RIR comes in. It links your perception of exertion to a predicted number of reps in reserve. (4) To my knowledge, powerlifter Mike Tuscherer popularized this model.

Powerlifters and bodybuilders are like good neighbors – they share each other's sugar. So, even if you're more interested in showy muscle than maximum strength, be aware of RIR. It serves as the basis of many autoregulated resistance-training methods, allowing you to manipulate loads, sets and/or reps based on how you feel.

Selecting an appropriate exercise intensity for tri-sets is challenging and may open the door for training errors when repetition volume is fixed. Outside of occasional "lucky guesses," average lifters (myself included) are unlikely to accurately self-select loads that facilitate ascending levels of effort at pre-set rep volumes for grueling tri-set training.

Therefore, a very simple application of RIR works best: Use RIR to autoregulate the number of reps per set (rep volume).

Here's how it works: Simply perform reps until you perceive that you only have the goal number of reps "in reserve."

Here's a reminder for ascending effort tri-sets: You want to leave 3 reps in reserve for the first exercise. For the second, leave 2 RIR, and for the final exercise, you want to leave 1 RIR.

On a good day, you'll be able to do more reps. On a bad day, you'll perform fewer. You'll likely perform more reps before reaching your RIR target during the first "round" of tri-sets than the final.

And as a bonus for bodybuilders, this method of autoregulation is extremely robust against errors in load selection. We build muscle across a wide rep range, provided sets are taken close to failure. It doesn't much matter whether we complete 6 or 16 reps per set. The ascending effort tri-set structure helps you take every set close to failure while managing your fatigue.

Do the multi-joint exercise first. This exercise is the most technically demanding and trains the greatest amount of muscle mass, so you'll want to be fresh.

The second exercise is an isolation exercise related to the movement pattern. This should be the lower priority isolation exercise for your training goals.

The third exercise is also an isolation exercise related to the primary movement pattern, but it trains a high-priority muscle group. This muscle group receives some relative rest during the second exercise, allowing for partial recovery.

Isolation exercises train less complex movement patterns and less muscle mass and may be taken to closer to failure with reduced residual fatigue.

So let's say you're doing an upper-body pull tri-set, and your goal is to build a broad, barn-door back. You might begin with lat pulldowns (compound exercise), place EZ-bar curls second (isolation, a lower priority), and straight-arm pulldowns last (isolation, a high priority for large lats).

Lifters with physique goals commonly aim for 10-20 weekly working sets per muscle group. If programming traditional sets with 2-3 minute rest intervals between each, you'd better clear your schedule. Alternatively, busy lifters might consider tri-sets, which accumulate a lot of volume in a short time period.

Traditionally, tri-sets and compound sets have been considered advanced training methods. Newbies can make gains from sparse programming, so why subject them to the risks of undue fatigue and repetition failure?

Although experienced lifters typically know how to handle repetition failure safely, they're not spared from the consequences of accumulated fatigue. These consequences may include suboptimal training adaptations, sleep issues, mood disturbances, and more.

Using autoregulation with tri-sets will help you avoid inappropriate programming caused by fatigue and other life stressors. Newbies and seasoned lifters can use RIR to make time-efficient tri-set training structure more user-friendly.

That said, autoregulated tri-set training is still best for those who have experience taking sets close to failure, have adequate cardiovascular capacity, and have little or no need to demonstrate peak performance within 24 hours of the training session.

Tri-sets can be a powerful tool when pressed for time. Ascending effort tri-sets will help ensure that you can come back for more.

  1. González-Badillo JJ et al. The importance of movement velocity as a measure to control resistance training intensity. J Hum Kinet. 2011 Sep;29A:15-9.
  2. Hackett DA et al. Accuracy in estimating repetitions to failure during resistance exercise. J Strength Cond Res. 2017 Aug;31(8):2162-2168.
  3. Iversen VM et al. No Time to Lift? Designing time-efficient training programs for strength and hypertrophy: A Narrative Review. Sports Med. 2021 Oct;51(10):2079-2095.
  4. Helms ER et al. Rating of perceived exertion as a method of volume autoregulation within a periodized program. J Strength Cond Res. 2018 Jun;32(6):1627-1636.
  5. Weakley JJ et al. The effects of traditional, superset, and tri-set resistance training structures on perceived intensity and physiological responses. Eur J Appl Physiol. 2017;117(9):1877–1889.
Merrick Lincoln is a Michigan-based Doctor of Physical Therapy, Assistant Professor of Kinesiology at Saginaw Valley State University, a strength and conditioning coach, and sports science researcher. Follow on Instagram