How Your Body Adapts to the Stress of Exercise & the Importance of Not Overtraining


Two young females enjoying working out. How Your Body Adapts to the Stress of Exercise & the Importance of not overtraining

Overtraining – As with most things in life, there’s a “sweet spot” for exercise. You need to challenge your body to see change, but not to the point that you’re injured, fatigued, or overtrained. At the other end of the spectrum, your body needs to experience enough of a training stimulus that it’s forced to change. Striking a happy balance with your training will help you become stronger, fitter, and have a healthier body composition.

How Your Body Adapts to Exercise

When you first begin an exercise program, every exercise feels hard. That’s because you’re asking your body to do movements it isn’t accustomed to. According to general adaptation syndrome, your body adapts to exercise or any kind of new stress in three phases:

Weeks 1-3: Your body is caught off guard by the training you’re asking it to do. This is the “alarm” stage. The newfound stress on your body activates the sympathetic or “fight-or-flight” portion of your nervous system. You feel sore after your workouts as you’re creating microscopic tears in muscle fibers that must be repaired. Along with repair comes growth and strength gains.

Weeks 4-16: Your body slowly begins to adapt to the stimulus placed on it. Those squats and deadlifts that were once so challenging now seem more tolerable. Your body is also making subtle adaptations that make it more efficient at doing the exercises. In response to the load you place on your muscles, you begin laying down new muscle fibers and your nervous system is becoming more efficient at telling your muscles what to do. Initially, most of the adaptation is the nervous system becoming better at communicating with your muscles. Changes to muscle architecture begin only after 4 to 6 weeks.

Weeks 12-16: At this point, your body is starting to adapt to its training regimen and the routine no longer feels as challenging. You don’t experience the soreness you did in the beginning and aren’t as challenged by the workouts either. Unless you make changes, your body will no longer feel the pressure to further adapt and change.

It’s also at this point that your body can become exhausted if you’ve place TOO much stress on it. You see this in hardcore athletes and bodybuilders who try to advance their training too quickly or do too high of a training volume. That’s why recovery is so important. Training is challenging to your muscles as well as your neurological system and without rest and recovery periods between training sessions, you run the risk of exhausting your system. Excessive training without enough recovery time doesn’t give your joints, muscles, ligaments, tendons, and nervous system a chance to recover from the stress you’re placing on them. In some cases, this can lead to a rise in cortisol, which has a negative impact by suppressing your immune system, interfering with sleep, and reducing insulin sensitivity. Plus, cortisol is a catabolic hormone that can counteract attempts to gain muscle by fueling muscle breakdown.

In reality, this sequence of events happens any time you change the stimulus you place on your muscles, for example, when you increase the resistance you use or the volume of your training, and it’s these changes that lead to muscle growth and strength gains. Unfortunately, you can also become so comfortable with your workout that you don’t challenge your muscles enough to force them to continue to adapt and change. At that point, your workout becomes stagnant. You maintain the gains you’ve already made but you don’t make new gains. So, it’s a balancing act. You need enough stimulus on the muscles to make them grow without exhausting them and yourself to the point that muscle breakdown becomes a problem. How do you maintain that balance? Here are some tips:

Give Your Muscles Periods to Deload

Use a periodized approach to training. Periodize your workouts so you’re working at a high resistance & lower volume during some periods and low resistance, high volume during others. This varies the stimulus on your muscles. It also helps prevent a plateau while giving your muscles a lighter load for periods of time. If you don’t periodize your workouts, including a week of lighter training every 4 weeks or so to let your muscles recuperate. You can either lower the resistance or work on some other aspect of training such as flexibility. Doing this can also help you mentally stay motivated and avoid burnout.

Build Adequate Recovery Time into Your Training

You already know it but it bears repeating – give the muscle groups you just worked a full 48 hours for recovery, especially if you’re lifting at a high percentage of your one-rep max. Not doing this will not only overly tire your muscles but can actually interfere with gains. It’s during rest periods between strength workouts that your muscles grow.

Don’t underestimate the power of sleep either. Getting less than 7 hours of nightly can stress your body and lead to excessive release of cortisol. As mentioned, cortisol is the enemy when you’re trying to build muscle due to its catabolic effects.

Focus on Nutrition Too

It goes without saying that you need nutrition to support your training and that means getting enough calories and protein. You can’t skimp on nutrition and expect your muscles to continue to grow and become stronger. Amino acids from protein are the building blocks of muscle tissue and you need carbohydrates to replenish muscle glycogen stores. Whole foods are the ideal choice for fueling your workouts.

Monitor for Signs of Overtraining

Listen to your body. If you’re feeling exhausted all of the time or finding it hard to get through workouts, give your body a much-needed rest – or at least scale back the intensity of your training for a week or two. Check your heart rate first thing in the morning before getting out of bed. If your heart rate rises above baseline by more than 7 beats-per-minute, you’re likely pushing too hard. Overtraining can activate your sympathetic nervous system and cause an increase in heart rate.

Abide by the Principle of Progressive Overload

You won’t continue to see change if you don’t continue to challenge your muscles. You can do that by manipulating a number of training variables, including the resistance, total training volume, number of sets, number of reps, number of exercises, exercise order, rep tempo, type of exercises, training frequency, and by doing different variations of the same exercise. Don’t let your workout get stagnant. Stagnation is never good when you’re trying to build greater fitness or a better physique.



American Council on Exercise. “6 Signs it’s Time to Switch Up Your Workout”
Sports Med. 2007;37(2):145-68.
Exercise Physiology. McArdle, Katch, Katch. Eighth edition. 2015


Related Articles By Cathe:

5 Things You Can Do to Prevent Overtraining and Decreased Performance

Strength Training: Avoid These 5 Mistakes When Lifting Heavy

5 Things You Might Be Getting Wrong about Rest Days

Can You Build More Muscle by Sharpening Your Focus?

How to Break Out of a Strength Training Plateau

4 Common Mistakes Women Make When Training with Weights


Hi, I'm Cathe

I want to help you get in the best shape of your life and stay healthy with my workout videos, DVDs and Free Weekly Newsletter. Here are several ways you can watch and work out to my exercise videos and purchase my fitness products:

Get Your Free Weekly Cathe Friedrich Newsletter

Get free weekly tips on Fitness, Health, Weight Loss and Nutrition delivered directly to your email inbox. Plus get Special Cathe Product Offers and learn about What’s New at Cathe Dot Com.

Enter your email address below to start receiving my free weekly updates. Don’t worry…I guarantee 100% privacy. Your information will not be shared and you can easily unsubscribe whenever you like. Our Privacy Policy