Many myths have arisen surrounding weight training and exercise, some of which have a basis in reality, and some which are completely false.  Hopefully I can clear up some of these misconceptions by providing information that is scientifically based.

SPOT REDUCTION

It is a common belief that training a particular body part will burn and lower the fat for that specific part or your body, this is known as spot reduction.  An example of spot reduction is performing crunches to reduce subcutaneous abdominal fat.  Research indicates that this idea is false.  A person cannot target and drop fat from one area of the body.

The body reduces fat accumulatively through reducing caloric intake and increasing caloric expenditure.  So in order to lower abdominal fat, a reduction in total body fat is required. Crunches may improve the size and shape of abdominal muscles but will not specifically drop fat in the midsection.  In fact, males generally have a predisposition to store abdominal fat and it will often be the last fat removed from the body as you progressively get leaner.

MUSCLE AND FAT TISSUE

Some people incorrectly believe that muscle tissue will turn into fat once a person stops training.  In reality, fat tissue and muscle tissue are two distinctly different tissues in the human body.  A muscle cell cannot turn into a fat cell.  There is, however, a hint of truth as to how the expression “muscle will turn in to fat" arose.

When someone stops exercising, your muscles will adapt to the new demand.  Your muscles will get smaller and weaker if the demand is less than before- they will atrophy.  To make matters worse, most trainees will not significantly reduce their diet in order to compensate for the lack of exercise and activity level.  The excess calories will now be stored to fatty deposits, which will increase your overall body fat.  In addition, your ability to use calories is reduced when you lose muscle because your metabolic rate slows down.

The myth is derived from simply a combination of muscle atrophy and increased fat storage. If you stop training without adjusting your food intake, you will have less muscle and more fat.  Since fat tissue is not as dense as muscle tissue, it can create an appearance that your muscle turned to fat.  Even though you may stay at the same weight, your body part measurements can increase because fat is not as dense as muscle.

ABDOMINAL MUSCLES

Abdominal muscles are like any other muscle tissue; they don’t necessarily respond to training every single day and performing hundreds of repetitions.  Abdominal muscles can be overtrained like any other muscle of the body.  It is important that they receive an adequate amount of rest to recover from each exercise session.

It is true that the abdominals recover quicker than other muscle groups, so they can be trained more frequently.  A good guideline to follow is to not train your abs more often than every 48 hours, or every other day.  This will allow for sufficient recovery and prevent overtraining, which will result in diminished gains.  Both conventional abdominal exercises that solely tone the superficial abdominal muscles and core-stability exercises that target deeper muscles in the abdomen, should be implemented up to 3-4 times per week.

LOSS IN FLEXIBILITY

Many people fear that they will become “muscle-bound” if they participate in a strength training program.  As long as you follow correct strength training principles and stretch on a regular basis, your flexibility will not be lost and should in fact improve.  It is important to perform each exercise using a full range of motion.  The muscle should be exercised through a full extension and full contraction.  Be sure you feel a deep stretch at the bottom of a movement and do not perform only partial reps.

Another principle to follow is to train the body in balance.  If all you do is bench pressing and neglect back training, your flexibility will greatly diminish and your posture will worsen.  Your chest muscles will become overdeveloped compared to your back muscles, causing your shoulders to round forward.  It is essential that antagonist muscles receive equal amount of attention.  Joint mobility and flexibility will tend to increase if you train opposing muscles on each side of the joint with an equal amount of exercise.

REDUCTION IN SPEED

Long ago coaches used to tell their athletes not to train with weights because it will make them slower.  Actually the opposite is true, weight training can increase your speed. Increases in muscular strength will enable you to move faster, if body fat is not concurrently increased. Human movement is determined by muscle contraction.  So if your muscles are able to contract with more force, you will move faster.  Practically all athletes, such as football players, basketball players, sprinters and boxers, participate in a resistance training programs.

HIGHER REPS TONE MUSCLES

Several gym goers believe that you should use lighter weights and higher repetitions (15-25 reps) in order to “tone” muscles and burn more fat.  Increasing repetitions does have its place in an exercise program by improving muscular endurance.  Losing body fat, however, happens by expending more calories than you intake.  The type of strength training you do does not burn more fat.  The only way it will “tone” your body is if you have created a calorie deficit.

For weight loss it is good to use a variety of rep ranges in your training routine, include cardiovascular training and create a calorie deficit.  The lean, defined look comes from losing body fat, not from training with high reps.  If you compromise your intensity by using less weight, less fat will be burned during your workout because you will be burning fewer calories with a reduced intensity.  That is why it is important to take sets to positive failure despite which rep range you choose to worth through.

You should not try and turn your anaerobic workout into an aerobic one, the duration of your set will not last more than 20-30 seconds anyway.  Oxygen is required to burn fat, aerobic exercise means “with oxygen”.  Anaerobic means “without oxygen”.  The extra reps you perform in attempt to “tone” the muscle is not going to turn weight training into aerobic exercise.

I still recommend you perform abdominal movements with higher repetitions.  Muscle hypertrophy is not really the goal with training abs.  If you increase muscle growth at the waistline, you may take on a “blocky” appearance.  The higher repetitions are not burning fat or exactly “toning” the muscle.  Training abs with higher reps will help create an aesthetic appearance only if you shed subcutaneous fat through exercise and diet.

SHAPING THE MUSCLE

There is a large misconception that you can shape you muscle in certain ways that is simply not genetically possible.  People do cable crossovers, for instance, thinking that they are targeting the inner pectorals.  But since the muscle fibers run parallel, from the middle of the rib cage to the humerus (upper arm bone), it is impossible to target just the inside portion of the fibers.

This is due to the all or none principle.  A muscle fiber contracts completely or not at all. Once a stimulus is above the threshold value, the muscle contracts completely or more specifically– the motor unit.  Since the fibers run horizontally, the entire muscle fiber will contract, not only the inside part or outside portion of the fiber.

Since the fibers do run horizontally, you can target the upper, middle or lower areas of the chest.  This can be done by training the chest at different angles, such as doing incline presses for the upper pecs.  Doing cable crossovers and squeezing hard at the top will not work your inner chest anymore than doing dumbbell flyes short of touching the dumbbells together.  Obviously you want to work through a full range of motion, but remember a muscle fiber contracts completely or not at all.

The higher amount of force necessary, the more motor units recruited for the task.  Using heavier poundage will require the muscle to exert a higher force than if you used a lighter weight.  The number of motor units and their size primarily determines the force a muscle exerts.

Trying to attain a higher bicep peak is common, or striving to get an 8 pack when you only have 6 abdominal muscles.   You cannot change the predetermined, genetic shape of your muscles.  You can, however, make them bigger which may appear to change the shape.  So in a sense, muscle hypertrophy changes the shape of your muscles.