Some women shy away from lifting heavy weights, believing they’ll get bulky. For females, that’s not a worry. Women lack the hormonal makeup to build bulky muscles and have to work hard to increase their lean body mass at all – but doing so has a number of advantages. For one, when you add more lean body mass your metabolic rate increases so you burn more calories at rest. Plus, you’ll look more defined. You’ve probably known more than a few people who are “skinny fat” meaning they carry a high percentage of body fat even though they’re at or below their ideal body weight and their muscles aren’t defined. Being “skinny fat” carries some of the same risks health-wise of being overweight. Resistance training helps you avoid this problem, especially as you grow older.
Genetics is one factor that determines how much lean body mass you can build but how you work out matters too. The amount of resistance you use, how many reps you do and the rest time between sets all play a role in how much lean body mass you develop. As you might expect, diet is also a factor and how much cardiovascular exercise you do can impact muscle growth. If you do extremely long sessions of cardio, especially if you don’t consume enough calories, it can interfere with your ability to build muscle.
Muscle Tension: One Factor That Stimulates Muscle Growth and Lean Body Mass
Muscles grow by an increase in fiber size. Along with an increase in the size of the fiber, the connective tissue and fluid within muscle expands as well. Of course, you have to overload the muscle through resistance training for these changes to take place. When you place stress on a muscle by lifting a challenging weight, cells called satellite cells, a type of stem cell, donate their nuclei to help muscle fiber growth. For this to happen you have to generate enough tension by lifting a weight or using resistance that generates enough damage to stimulate satellite cells that help muscles grow.
How much resistance do you need to generate enough muscle tension to stimulate growth? For muscle growth and hypertrophy, most experts recommend using a weight that’s between 70 and 80% of your one-rep max. Using lighter weights will be most effective for increasing muscular endurance but not very effective for increasing muscle size.
The number of reps also impacts your ability to build muscle. To increase the size of the muscle, you need to recruit a maximum number of muscle fibers and place the muscle under tension for an adequate period of time. To build muscle, eight to twelve reps with the final rep being difficult to complete is ideal. Doing fewer than six reps and you’ll get mostly neuromuscular adaptations that primarily boost muscle strength. If you can do more than twelve reps, you’re essentially doing a muscle endurance workout and won’t see much increase in size.
The Role of Muscle Damage in Muscle Hypertrophy
You also need a certain training volume to stimulate muscle growth. Muscles need to spend enough time under tension to create muscle damage that leads to growth. That’s why the optimal formula for building muscle is six to twelve reps for each exercise and two to three sets with the last rep being a challenge.
Why is muscle damage so important? Damage causes an inflammatory response. This inflammation recruits satellite cells that help muscle fibers repair and become larger. Local inflammation is a good thing when it comes to building lean body mass.
Metabolic Stress and Muscle Growth
Another factor that contributes to muscle growth is metabolic stress. When you do resistance training and feel your muscles burning, you’re experiencing the effects of metabolic stress. This is a whole sequence of events whereby lactic acid, hydrogen ions, and inorganic phosphate build up. This triggers the release of hormones like growth hormone, IGF-1, and catecholamines that stimulate muscle growth and boost fat-burning.
You can maximize the amount of metabolic stress your muscles are exposed to by reducing the rest time between sets – but it’s a balancing act. If you rest for only thirty seconds, you’ll maximize metabolic stress, but you’ll reduce the amount of tension you can generate on the next set since your muscles haven’t fully recovered. A rest period of between one and two minutes seems to be an ideal balance since it allows sufficient muscle recovery but still exposes your muscles to metabolic stress.
Summing It Up
The best formula for muscle hypertrophy:
A resistance that’s 70 to 80% of your one-rep max
Two to three sets of 8 to 12 reps with a weight that makes the last rep difficult to complete
A rest period between sets of 1 to 2 minutes between sets
Compound exercises, exercises that work more than one muscle group at a time, are best for building lean body mass since they recruit a maximal number of fibers, leading to more damage, and also create the most metabolic stress.
To continue to progress, you’ll need to progressively overload the muscles you’re trying to build. When the final rep is no longer as challenging, it’s time to increase the weight.
Even when you’re progressively overloading the muscle, you may reach a plateau. That’s when you’ll need to alter things by changing your exercise selection, the order in which you do them, the tempo, how long you rest between sets, etc. There are lots of ways to do this to jump-start growth. Regardless of the workout you do, the three factors – muscle tension, muscle damage, and metabolic stress, are all important for muscle growth and development.
Of course, there’s nothing wrong with using lighter weights and more reps for a muscle endurance workout to avoid overtraining and to add variety to your workout. There’s no need to lift to failure every time you work out. Don’t forget to rest muscle groups that you work for at least 48 hours before training them again. You need time for those satellite cells to help your muscles repair and grow – and give you the results you’re looking for.
References:
J Appl Physiol, 105, 1454-1461.
Sports Med. 2013 Mar;43(3):179-94. doi: 10.1007/s40279-013-0017-1.
Aaron Bubbico and Len Kravitz, Ph.D. “Muscle Hypertrophy: New Insights and Training Recommendations”
Related Articles By Cathe:
Is It Harder to Build Muscle When You Have More Body Fat?
Do You Have to Lift Heavy Weights to Build Muscle?
Is Muscle Damage Necessary for Muscle Growth?
What Role Does Mechanical Tension Play in Muscle Hypertrophy?
Hypertrophy Training: Does Training Too Often Interfere with Muscle Growth?
3 Factors That Fuel Muscle Growth
How Do You Know if You’re Gaining Muscle When You Strength Train?
Related Cathe Friedrich Workout DVDs:
STS Strength 90 Day Workout Program
All of Cathe’s Strength & Toning Workout DVDs
Total Body Workouts
Lower Body Workouts
Upper Body Workouts
