How Many Sets for Size vs Strength?

While increased muscle size is associated with increased strength it is not a perfect relationship meaning you can increase muscle strength without increasing muscle size.   Research shows that the ideal number of sets for muscle growth vs muscle strength seem to differ, and the ideal number of sets definitely changes as you progress from a beginner to a more advanced lifter.

To tease apart the differences it is useful to review what happens when a person starts doing resistance training exercise and how things change as they have been doing resistance training on a regular basis for 3 – 6 months or longer.

When a person starts doing resistance training they can make very quick gains because they are going through a period of “motor learning” and “neural adaptations” meaning they are learning how to do the exercises.     This process ends pretty quickly in about 3 – 4 weeks of doing resistance training.  During this time strength improvements are not associated with much muscle growth.  Once this honey-moon period ends people start to add muscle if they continue to challenge their muscles sufficiently and this is known as muscle hypertrophy.    

How hard someone trains is measured by how close to complete muscular failure they reach during each set of exercise.  Muscular failure is defined as continuing to do an exercise until you reach a point of fatigue where you can no longer lift a weight using good form.   The closer to this point that you get the more intense the set and sets done to muscular failure are the most intense.

For beginners one set to failure can be sufficient to stimulate muscle growth and strength increases as long as the person continues to increase the resistance when they hit a certain number of repetitions in a set of a particular exercise – somewhere between 8 -12 reps is a good goal.

However, as time goes on many people begin to plateau if only doing 1 set of exercise for each major muscle group.   At this point introducing multiple sets of each exercise is often key to continuing to gain muscle size and strength.

Number of Sets for Size vs Strength

For more experienced lifters the number of sets and rest time between sets should be determined based on goals and performance during each resistance training workout (this is why it is VERY important to record all your workouts listing exercises done, weight or resistance level used, rest time between sets, etc.).  

A recent study in the Journal of Applied Physiology provided some very valuable information about sets for strength vs size.    The study had 85 people do sets of between 8 – 15 repetitions of single-leg knee extensions with weight chosen so they reached muscular failure during each set.    Each participant did one set per workout with one leg and four sets per workout with the other leg.    Muscle size changes were measured with MRI.    60% of the participants failed to gain more than a 3.3% increase in quadriceps muscle size for their leg that only did one set.    For the leg that did four sets per workout only 19% failed to gain significant increases in muscle size.

Other studies have also found that multiple sets are better for muscle size.   However, research on multiple sets for strength gains are not as consistent!   In the study above the four set legs did NOT gain significantly more strength than the 1 set legs.   This does not mean that people focused on strength should not do more than 1 set of exercise.    Most elite powerlifters do multiple sets of exercise.      However, this does indicate that for non-competitive lifters strength goals can probably be met with less sets than those looking to maximize muscle size.

What About Set Intensity and Rest Time Between Sets?

Another key point is that studies clearly show that for increasing muscle size it is very important to come close to muscular failure or actual hit muscular failure during each set.   In addition, shorter rest times tend to be better for muscle growth for more experienced lifters.

This is NOT the case for strength.   Research shows that excellent strength gains can be made doing sets that “leave something in the tank” and not reaching muscular failure while also taking longer rest times between sets.   This does not mean that strength focused lifters should never achieve failure in training.     However, as a person becomes strong it becomes more and more risky to use high loads to complete muscular failure – particularly in major compound lifts like squats and deadlifts.    

Can You Turn Fat into Muscle?

 

The short answer is no – fat does not get transformed into muscle.     Fat and muscle are two different tissues.  You can increase muscle mass while you decrease fat mass, but fat is not converted into muscle.  In the same way muscle cannot be converted into fat.  Fat is created whenever we take in excess calories from fat, protein, carbohydrate (or alcohol).  In this case the calories ultimately end up being converted to triglyceride and stored in fat cells.

 Each molecule of triglyceride (fat) consists of a carbon, hydrogen and oxygen.  To get rid of a single molecule of triglyceride takes many enzymes and biochemical steps to completely oxidize fat.  The complete oxidation of 10 kg (22lbs) of fat requires 29kg of oxygen consumption and the production of 28 kg of carbon dioxide and 11 kg of water (H2O).  The carbon dioxide is excreted by the lungs while the water is excreted as urine, sweat, breath, tears or other bodily fluids.  

Building muscle is a whole different process.  Three key mechanisms are responsible for initiating muscle growth:

Muscle Tension – all forms of resistance training force muscles to create tension to support and move the load.    Enough tension in the muscle causes changes in the chemistry of the muscle allowing for growth factors to be secreted such as mTOR and satellite cell activation.   Tension can come from active tension where muscles actively contract and also from passive tension which is stretching which tends to occur during the lengthening (eccentric) phase of a resistance training exercise.    

Active tension tends to result in muscle fibers becoming wider while passive tension can make them longer.

Muscle Damage – damage to muscle cells causes a release of inflammatory chemicals and immune cells that activate satellite cells to come into action.     This also initiates muscle growth.

Metabolic Stress – When you feel the “burn” or the “pump” when lifting weights, you are feeling the effects of metabolic stress.   Metabolic stress from high levels of anaerobic energy production helps contribute to muscle growth without necessarily increasing the size of the muscle.   This is from the addition of glycogen (multiple glucose units linked together in the muscle), which helps to swell the muscle.   This type of growth is often referred to as “Sarcoplasmic Hypertrophy” and can increase the appearance of larger muscles without increasing muscle strength or the size of muscle fibers.   Increased fiber growth is referred to Myofibrillar Hypertrophy referring to the fact that myofibrils (muscle fibers) are growing.

In summary, for muscle building to occur you must force your muscles to adapt by creating stressors including increased tension, muscle damage, and metabolic stress and then eating properly and resting to allow the muscles to recover and grow.  

 

Lengthened Partial Reps for Faster Muscle Growth

 

A new study finds 'lengthened partials supersets' can lead to 43.3% more muscle growth.    The study adds to the growing body of evidence suggesting that doing resistance training sets and reps in extended positions emphasizing the stretched portion of a repetition enhance muscle hypertrophy (muscle growth).

Long muscle length partial reps focus on the stretched portion of an exercise’s range of motion where muscles are at their longest (right figure in graphic above).   7 out of 8 studies showed that training in the stretched position led to greater muscle growth compared to the contracted position when muscles are short.

Even more interesting is that 4 out of 5 studies found that long-length partial repetitions were superior to full range of motion for hypertrophy.   One study showed double the muscle growth in the hip extensors (think glutes and hamstrings) with lengthened partials compared to full Range of Motion sets (+6.8% vs +3.1%).

This enhanced hypertrophy from long-length partials may be due to:

Increased time under tension in the most anabolic part of the range of motion.

Greater mechanical tension on muscle fibers when stretched.

Three Methods to Incorporate Lengthened-Partial Reps into your Program

Start with full Range of Motion (ROM) repetitions, then switch to long-length partials when you can no longer complete full reps.   This extends the set and increases the volume.

Perform entire sets using only the stretched half of the ROM such as deep squat to halfway up only or bottom of bench press to half way up only.    This maximizes time under tension in the lengthened position.

While promising there are many benefits to full range exercise including the ability to handle higher loads and increasing maximum strength in the muscles shortened position such as to of the squat.