4 Surprising Factors That Interfere with Muscle Gains



Building muscle size and definition takes time, patience, training, and good nutrition. Get the training OR nutrition component wrong and you’ll struggle to make the gains you’re working so hard to achieve. Yet, factors other than what you eat and how you lift can limit your strength and size gains. If you’re struggling to make gains, make sure none of these factors apply to you.


Did you know some medications make it harder to build muscle? One medication many people use for muscle soreness is ibuprofen. It and other non-steroidal anti-inflammatory drugs (NSAID) can potentially put a damper on muscle growth.

While research is conflicting with regard to NSAID & inhibition of muscle growth, some studies show that taking NSAID reduces muscle protein synthesis. Yet, other studies show that taking NSAID may actually ENHANCE muscle growth. How’s that for conflicting data? Whether or not NSAID are detrimental may depend on the dose you take and how long you take it. If you take it on a regular basis or take higher doses, it may interfere with muscle protein synthesis, a prerequisite for muscle growth.

Another common class of medications, birth control pills, may also reduce muscle gains. In one study, researchers asked 73 young, untrained women to participate in an intense resistance training program. The women trained 3 times a week for 10 weeks using 75% of their one-rep max. The workout was designed to build muscle size. Some of the women were taking birth control pills while others were not. The results? Those who were taking birth control pills gained 40% less muscle mass relative to those who were not.

How do birth control pills interfere with muscle growth? In the study, women on birth control pills were found to have lower levels of anabolic hormones and higher levels of the catabolic hormone, cortisol. The problem with cortisol is it breaks down muscle tissue. So, being on birth control pills may reduce gains in muscle size.

Not Enough Rest and Downtime 

Lack of rest comes in two varieties – not enough sleep and not enough recovery time between weight-training sessions. You’ve heard it before: Muscles grow during the downtime BETWEEN workouts. If you’re not giving your muscles enough time to recover, they can’t repair or build new muscle tissue. It might seem that lifting more often would help your muscles grow but there’s a point of diminishing returns. Just as dropping your calorie intake too much is detrimental to fat loss, overdoing the weights makes it harder for your muscles to grow. The general rule is the harder you work your muscles during a session, the more recovery time they need. At the very least, the muscles you work need 48 hours of “recoup” time.

The other type of downtime your body needs after a weight-training workout is sleep. It’s during deep sleep that your brain pumps out more growth hormone, an anabolic hormone that boosts muscle protein synthesis. If you’re not sleeping 7 hours or more nightly or have poor sleep quality, your body will spend less time in deep sleep and you may not grow as much.

If you cut back on sleep even more or do it longer term, your cortisol level can rise. Cortisol is a catabolic hormone that breaks down muscle tissue. Combine lack of sleep with excessive training and you’ll experience an even greater surge in cortisol to interfere with your muscle gains. The way to avoid this? Make time for rest, recovery, and sleep.

Too Much Cardio 

You may have heard about the “interference effect,” the idea that too much cardio interferes with how your body adapts to weight training. In theory, this makes sense. Your muscles adapt differently to strength-training than to cardio. Yet, research in this area is inconsistent. Some research suggests that doing cardio and strength-training on the same day doesn’t impact strength gains and may actually increase the benefits of strength training.

Other studies suggest that cardio only interferes with strength gains in the muscles you worked doing cardio, typically the lower body. In other words, doing cardio and strength training on the same day could reduce strength and hypertrophy gains in the lower body but not the upper body. Also, running is more likely to interfere with strength adaptations than cycling.

What does seem clear is that doing TOO much cardio can send your body into a catabolic state. Plus, if you spend a disproportionate amount of time doing cardio, you lower your energy reserves and may not have the stamina to push hard with weights. Consider keeping your cardio sessions short and intense (high-intensity interval training) and do them on a day you’re not doing a tough strength-training workout. If you have to do cardio and strength training on the same day, do strength training first.

Too Much or Not Enough Consistency 

Consistency is important to see any kind of fitness gains. You won’t make gains training on an irregular basis. On the other hand, TOO much consistency can thwart gains in muscle size too. If you do the same workout using the same weights every time you train, the gains will stop. This happens because your body adapts to doing certain movements and need to be challenged in a different way. After a few weeks, change one of the training variables listed below:

  • Resistance you’re using
  • Training frequency
  • Type of exercises
  • Tempo or repetition speed
  • Number of reps or number of sets
  • Workout frequency
  • Order of exercises
  • Rest intervals
  • Whether you use dumbbells, barbells, or resistance bands.
  • The angle at which you do an exercise.
  • Stance – change the exercise by placing your hands or feet closer or further apart.

The key is to CHANGE something so that your muscles get a new stimulus. Besides changing the above variables, you can introduce more advanced techniques, like supersets, giant sets, and tri-sets. Another approach is to focus more on compound exercises where you’re working multiple muscle groups. The key is to not let your body adapt and stop adapting. Force it to keep changing by introducing new challenges.

The Bottom Line 

As you can see, there’s more to the muscle growth equation than how you train and how you eat. Other factors have an impact too. Now you know what some of them are.



Science News. “Birth control pills can limit muscle-training gains”

Muscle Evo. “Do Pain Killers Put the Brakes on Muscle Growth?”

JCEM. “Skeletal Muscle PGF2αand PGE2 in Response to Eccentric Resistance Exercise: Influence of Ibuprofen and Acetaminophen”

Strength and Conditioning Research. “Should we avoid concurrent training to maximize hypertrophy?”

The Effect of Concurrent Training. Len Kravitz, Ph.D.

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