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Training Science

How Long It Takes to Lose Muscle If You Stop Training — Irvine Personal Trainer's Guide

By Kelsey Kennedy

Many of us occasionally have to take a break from our exercise routines, albeit it's not ideal. There are many reasons to take a break from exercising, including stress, illness, injury, travel, and the simple desire for a break.

Even though you desperately need the break, you might be concerned about losing all of your hard-earned muscle.

3 Days

If you don't exercise at all, you might begin losing muscle mass within 72 hours. After 72 hours without activity, even your heart, a muscle, will exhibit a decline in the amount of blood it can pump per beat.

Your heart will experience the results much more quickly than your biceps or quads. You will experience a little bit more breathlessness than usual if you go out on Monday, skip three days, and then work out again on Friday because your heart is pumping less oxygenated blood out with each beat.

Even if you begin to lose muscle mass after 72 hours, you usually won't notice any decreases until after 3–4 weeks have passed since your last workout. In a modest study, it was discovered that skilled men could skip three weeks of exercise without experiencing any discernible muscle loss.

What Leads to a Loss of Muscle Mass

How rapidly you lose muscle mass, depends on a few things, such as:

How long you’ve been training

The more muscle you have and the longer you've been lifting, the better off you'll be if you have to interrupt your routine. After a time of inactivity, if you're fit with developed muscles, you will still have a baseline of muscle that others will not have.

What you eat

For the purpose of gaining and preserving muscle mass, enough protein is very important. If you cut back on it, your body won't have enough amino acids to keep up with the constant breakdown and rebuilding of cells that takes place throughout the day. In order to receive the amino acids required to maintain your other cells and tissues working, your body eventually draws from its muscle reserves, which leads to muscle wasting.

One study, for instance, found that elderly women who were sedentary to moderately active and consumed a low-protein diet, lost around 14% of their muscle mass after nine weeks.

In order to avoid muscle loss, you must ensure that you consume adequate protein even when you’re not exercising.

Your age

It might be challenging to add muscle and keep it there as we age due to a number of factors.

Motor neurons start to die off as we become older, there is a sharp decline between the ages of 60 and 70. Our muscles contract when motor neurons receive signals from the spinal cord. It is more difficult to engage muscle fibers when motor neurons are lost. Muscle fibers won't break down and rebuild to get bigger and stronger if you can't recruit them.

Strength training can assist in reversing these nervous system alterations as well as other age-related changes, but the advantages progressively fade away after you stop working out.

The Takeaway

Several factors will influence how quickly you lose muscle after stopping your workouts, but in general, you'll start to see a difference in 3–4 weeks.

If you have to reduce your training schedule for whatever reason and you don't want to lose any of your hard-earned muscle, you might be able to get by with just two strength workouts per week. Do at least 1-2 sets of 8–12 repetitions for each exercise, and focus on every major muscle group.

You won't have to start from scratch once you resume your routine, even if you can't or don't want to train for a few weeks. If you've been exercising regularly up until your break, you should be able to quickly regain your strength and muscle mass.

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Frequently Asked Questions

How quickly do I start losing muscle if I stop training?

Your body starts losing a measurable amount of muscle mass after roughly 72 hours of inactivity. Noticeable decreases in strength or size typically don't show up until 3–4 weeks have passed since your last workout, especially for well-trained clients.

Can I maintain muscle with only two workouts a week in Orange County?

Yes. Two well-designed strength sessions per week — 1–2 sets of 8–12 reps for each major muscle group — is usually enough to hold onto most of your muscle mass during a busy stretch. Our coaches in Irvine, Orange, and Laguna Hills program exactly this type of minimum effective dose when clients are traveling or swamped with work.

Does protein matter if I'm not training hard?

Absolutely. Your body needs amino acids 24/7 to maintain its cells. If you cut protein too low during a break, your body will cannibalize muscle tissue to meet those demands — one study found elderly women on low-protein diets lost around 14% of their muscle mass in nine weeks.

Where can I find a personal trainer in Orange County to protect my gains?

Train With Dave has three Orange County studios — Irvine, Orange, and Laguna Hills — with coaches who program around your schedule, travel plans, and recovery needs. Start with a free 45-minute consultation.

How much does personal training cost in Irvine, Orange, or Laguna Hills?

Train With Dave averages $60 to $80 per session — and that includes a fully customized workout program, personalized nutrition plan, training app, and direct trainer access between sessions. Exact pricing is customized during your free consultation.


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About the Author

David Cozzens — Founder & Head Coach, Train With Dave

David Cozzens has been coaching personal training clients in Orange County for over fifteen years. He holds a degree in Exercise Science and is certified through NASM (CPT), the NSCA (CSCS), and Precision Nutrition. He founded Train With Dave to deliver fully-customized programming — workouts, nutrition, and direct coach access — at three Orange County studios in Orange, Irvine, and Laguna Hills. Train With Dave has been voted Best Personal Training across Orange County five years running — Best of Irvine 2022, 2023, and 2024, plus Best of Orange Personal Trainer of the Year 2025 and 2026 — with over 1,000 five-star reviews.

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