Most training programs answer this question with the cold confidence of a Soviet parking meter:

Rest 3.5 minutes.

Fine.

But why?

Why three minutes?

Why not two minutes and 17 seconds?

Are you actually recovered, or did the stopwatch simply finish counting while your lungs were still trying to chew through the front of your face?

Why would someone program the same rest period for all 4 sets as we know fatigue accumulates, thus you will need more rest before your last set than your first set.

Fixed rest periods are clean on paper.

Human physiology is not.

Plus this can change from day to day.

Some days, you crush a set of squats and feel ready to attack again before the bar stops rattling.

Other days, the same load leaves you folded over the rack, bargaining with several minor deities and wondering whether your hamstrings have legal representation.

This is where heart rate becomes useful.

Let Your Heart Decide When the Next Set Starts

​Inside Triphasic Training II, coach Cal Dietz and yours truly nerdy cover several biometric methods for autoregulating training.

One of the simplest methods uses heart-rate recovery to determine rest periods.

The setup is brutally simple:

Perform the set.

Watch your heart rate come down.

Begin the next set when it reaches your predetermined number.

For a main strength exercise, a good starting point is around 85 beats per minute.

Hit the set.

Recover.

When your heart rate reaches roughly 85 bpm, grip the bar and return to the scene of the crime.

Now your rest period matches your physiology / fatigue instead of forcing you to obey a number that was typed into a spreadsheet three months ago by a coach eating cold chicken and soggy broccoli over a laptop.

Why This Beats the Stopwatch

Recovery changes.

Sleep affects it.

Stress affects it.

Heat, hydration, conditioning, exercise selection, load, reps and accumulated fatigue all pile into the vehicle like heavily armed circus performers.

A heavy set of squats may require four minutes before your heart rate settles.

Later, another set of DB lateral raises may only require two and a half.

The stopwatch does not care.

It sits there counting with the emotional range of a microwave oven.

Heart rate gives you feedback from the organism (aka you) currently doing the training.

That is the entire point of autoregulation.

Use a Higher Trigger for Accessory Work

You do not need the same recovery target for every exercise.

For heavier compound lifts, start around: 85 bpm

For higher-repetition accessory work, try: 100–110 bpm

The higher trigger keeps the workout moving and carries more fatigue into the next set.

That may be useful when the goal is hypertrophy, local muscular endurance or creating enough metabolic distress that your triceps begin transmitting coded messages to the Coast Guard.

These numbers are starting points and can change.

They are not sacred commandments hammered into granite by the ancient prophets of leg day.

Adjust them based on the athlete, exercise and desired training effect.

This Works Especially Well for Remote Coaching

Cal puts it this way:

The athlete does not need a coach standing nearby with a stopwatch, clipboard and the haunted stare of a man who has watched 400 consecutive sets of Bulgarian split squats.

They only need a heart-rate monitor and a phone or watch.

A chest strap will generally give cleaner, faster feedback during lifting than a wrist sensor, but either can help establish the habit.

I have programmed rest periods this way for myself and my online clients for more than a decade.

It makes the program easier to follow.

More importantly, it adjusts to what is happening today.

Bad sleep?

Rest may take longer.

Excellent recovery?

You may be ready sooner.

The program bends without snapping in half and flying through the window.

You Do Not Need More Technology

Could you purchase velocity trackers for every rack?

Absolutely.

You could also install biometric eye scanners, surround the platform with motion-capture cameras and hire a former NASA engineer to monitor bar speed from an armored van in the parking lot.

Most people will not do that.

They just want to know:

How long should I rest before my next set?

Heart-rate recovery gives you a practical answer.

Perform the set.

Allow your heart rate to fall.

Once it reaches your target, go again.

Simple enough to use tomorrow.

Powerful enough to replace the arbitrary rest clock.

And considerably better than sitting on the bench scrolling Instagram until you lose all awareness of time, space and why you came to the gym.

The complete heart-rate protocol—including how to establish targets for strength, hypertrophy, speed and conditioning—is laid out inside Triphasic Training II.​

For more information about the Triphasic Training II book, I also write a separate daily newsletter covering practical methods from the system.

Go to Triphasic2.com and opt in.

Much love,

Dr Mike

PS - Here is what JG had to say:

—JG

____________

Mike T Nelson CISSN, CSCS, MSME, PhD
Associate Professor, Carrick Institute
Owner, Extreme Human Performance, LLC
Editorial Board Member, STRONG Fitness Mag

Mike T Nelson is a PhD and not a physician or registered dietitian. The contents of this email should not be taken as medical advice. It is not intended to diagnose, treat, cure, or prevent any health problem - nor is it intended to replace the advice of a physician. Always consult your physician or qualified health professional on any matters regarding your health.

..