What Happens When Muscles Don't Grow

One of the more controversial issues in the fitness world is why some people fail at exercise. That is, instead of getting fitter, leaner, and healthier, some people have a “non—response” to training in which they see little or no benefits for their efforts.

The most accepted view is that non-responders have a genetic make-up that makes exercise have little beneficial on their physiology.

On the other hand, it’s been suggested that non-genetic factors, such as an inability to push oneself physically or lack of familiarity with what it actually means to exercise, are what lead to poor results. In this view, it’s believed that many non-responders are simply not training as hard as everyone else, hence the lesser response in their measured training benefits (1).

Aerobic Exercise & Non-Responders

Lack of result is most common when people do moderate aerobic exercise, such as that which is a standard in public health recommendations. For example, in the Heritage Family study, which was one of the first studies to identify the phenomenon of non-responders, 15 percent of participants had no improvement whatsoever in their fitness levels despite 5 months of aerobic training (2).

A more recent study found that almost 40 percent of subjects who followed the ACSM guidelines for exercise, getting 30 minutes of aerobic exercise 5 days a week for 24 weeks, were non-responders who experienced zero improvement in fitness level (3).

This study was unique because it also tested the effect of bumping up the intensity to 75 percent of maximal and increasing the duration to 40 minutes (equal to running 5 miles in 40 minutes). When participants went harder and longer, every single person experienced a notable increase in fitness. There were no non-responders. Researchers think that two key factors make it more likely you’ll get positive results from training: Increase intensity and duration.

Enter Intervals

Of course, raising intensity and duration simultaneously increases the chance that trainees are not going to complete their workouts. Very few people enjoy cardio and making it harder and longer is not going to encourage compliance.

One alternative is interval training, which breaks up intense bouts with rest, providing mental relief while achieving a high degree of physiological overload to induce fitness adaptations. Fortunately, interval training not only improves fitness well beyond the gains seen with continuous aerobic exercise but it also appears to produce superior improvements in body composition.

A 1994 study illustrates the different outcomes between intervals and steady state exercise. Researchers compared the effect of 20 weeks of aerobic training (starting with 30 minutes at 65 percent of max and increasing to 45 minutes at 80 percent of max) with 15 weeks of intervals (15 sprints for 30 seconds each) (4).

Results showed that fitness levels increased the same amount in both groups, however, the interval group also had a large increase in the rate of fat burning as measured by the level of oxidative enzymes. Combined with a much greater afterburn in the recovery period, the elevation in fat burning resulted in a greater fat loss compared to the aerobic training group: They lost nine times more body fat and 12 percent more belly fat than the aerobic group as measured by skinfolds.

Train With Weights

Strength training is probably the most powerful form of exercise available to you. Not only are non-responders practically non-existent when strength training is performed, but you get numerous physical and mental benefits in addition to increased strength and mobility.

For example, a new study from the Netherlands found that that when older individuals performed a strength training program for 24 weeks, all participants experienced measurable results (5). This is noteworthy because older people have something that is known as “anabolic resistance,” which means that they don't build as much muscle as younger people in response to weight training.

This study had participants train 4 sets at loads ranging from 60 to 85 percent over the course of 24 weeks in the leg press and leg extension. By the end of the study, subjects gained an average of 1 kg of muscle, improved body fat percentage, and increased lower body strength by 50 kg (over 100 pounds). Interestingly, the duration of training was found to be a key factor in determining individual response to training: Those who had little or no improvement by 12 weeks showed a substantial improvement after 24 weeks.

The study authors conclude that even if an individual doesn’t experience gains in all measured outcomes when it comes to strength training, there are no non-responders. Everyone will benefit in some way, whether it’s in terms of an increase in lean body mass, muscle strength, or overall physical function. This combination can go a long way to promoting healthy aging.

As noteworthy as this study is, it’s just one of many. For example, a 2007 strength training study found that of 66 subjects ranging in age from 20 to 75 years old, 17 were classified as non-responders, experiencing no increase in muscle size after 16 weeks of lower body training (subjects did squats, leg press, and knee extension). Still, these “non-responders” all increased lower body strength a significant degree, providing support for the view that strength training always pays off in some way.

There were also 17 extreme responders who had an average 50 percent increase in muscle size and 32 moderate responders who grew their muscle fibers by 25 percent. Genes that regulate muscle growth accounted for the large difference in hypertrophy response. Extreme responders had more genes “turned on” whereas for non-responders the same genes were “off.”

Practical Steps To Training Success

The bottom line is that you need to plan training based on your unique genetics. All the evidence is pointing to the fact that the harder you train, the less likely you are to be a “non-responder.”

With that in mind, here are some steps to ensure you get individual results:

#1: Strength Train

Chances are, a primary goal of exercise is to improve body composition. Strength training is your go-to choice because it increases lean muscle mass, raising metabolic rate, while also improving your body’s ability to process carbohydrates and burn fat.

#2: Lift Heavy Weights

In order to elicit changes in body composition, it’s necessary to lift weights that are at least 60 percent of the maximal amount you can lift. One likely reason there are non-responders is that studies show people overwhelmingly sell themselves short, choosing intensities that are too light to yield measurable results.

#3: Train Your Whole Body

Instead of focusing on single body parts, train your whole body using multi-joint lifts like squats, deadlifts, overhead press, etc. Total body training allows you to lift heavier weights and it increases the metabolic cost of training so you burn nearly double the calories as when you do isolation training.

#4: Do Intervals For Cardio

Not only will you increase fitness and get the stress relieving benefits of regular cardio, but intervals also increase fat burning, trigger muscle synthesis, and elevate body composition hormones making it much more likely you’ll get a superior training response.

#5: Do Eccentric Training

Eccentric training is when you focus on the “down” motion of a lift, by using a longer tempo. For example, in the squat, you’d perform the eccentric phase by lowering yourself into the squat on a 6-second count, but raising yourself on a 1-second count. Eccentric training is a superior stimulus for muscle and strength development and it’s been found to increase the most powerful type 2 muscle fibers by 75 percent.

#6: Get Extra Protein

Eating extra protein supplies your body with the amino acid building blocks necessary to repair and build muscle tissue. Studies consistently show that when hard training is performed, extra protein in the post-workout period increases muscle and strength gains. Shoot for a minimum of 1.6 g/kg of protein a day in 25-gram doses.

#7: Take Creatine

Creatine is a short-term energy source for muscle. It can boost all forms of athletic performance. It's especially relevant for low responders because it increases cellular activity for greater muscle growth.

#8: Be Consistent

Strength and body composition changes are progressive. They don’t happen after one or two workouts. Progress requires you to string together a series of high-quality workouts in which you do similar exercises each time. The best way to take advantage of this fact is to pick a goal and train using a pre-set program that progressively overloads the body. Consistency is key.

#9: Be Patient

Everyone wants fast results. The reality is that changes take time. Accept that the successful people are the ones who show up and use their time wisely. Stay the course. Follow the plan.

#10: Expect To Be A High-Responder

We know from studies into the placebo effect that we are much more likely to win if we believe we are going to win. Another way to say this is you’ll never know how good of a hand you were dealt genetically until you play it with the expectation that it is a good hand. By believing that exercise is going to transform your body, there’s a much greater chance that it will!