Although weight lifting has long been associated with bodybuilding and power sports such as football and field events (shot put, discus, etc.), it is more popular with the general population than ever before.

Clearly, resistance training can favorably influence bone density andincrease the amount of muscle attached to the skeleton. Thus resistance training can reduce the risk of bone-related disorders such as osteoporosis and improve energy expenditure, reduce body fat content, and improve self-image.
What Are Options for Resistance Exercise?
Today there are numerous options for resistance training beyond free weights and weight machines. Many people use pulley machines and resilient resistance materials such as bows (for example, Bowflex®) and elastic bands (such as Soloflex®). Of course, in a pinch, gravity alone may provide enough resistance for a positive impact. For instance, people accustomed to a regular workout will often do a few sets of push-ups on the floor if no gym equipment is available. How Does Weight Lifting Increase Muscle Mass? The goal of most weight lifters is to increase the size of the muscles that are targeted. Muscle mass development through weight training hinges on the “overload” principle. The use of weights places a greater than normal stress (load) upon the challenged muscle fibers. The overload stimulates the muscle to grow primarily by increasing the size (hypertrophy) of the overloaded muscle fibers. This means that the muscle cells get thicker as well as get stronger. Therefore, as a biceps muscle enlarges from doing dumbbell curls it is really a reflection of an increase in size of the overloaded muscle fibers within that muscle. Although growth may occur in both Type I and Type II fibers, as mentioned, it is believed to be more significant in the challenged Type II fibers.

Weight lifting and other resistance exercise overloads muscle causing it to adapt to get stronger and thus bigger.
Processes Associated With Adaptation After Resistance Training:

• Building of more protein for myofibrils
• An increase in number of mitochondria
• An increase in enzymes specific to the task
• Making more connective tissue for sheathing around muscle fibers and bundles
• A slight increase in glycogen stores

How Do You Know How Much Resistance to Use to Promote Muscle Development?
To overload a muscle, three sets of six to ten repetitions is probably adequate to stimulate growth. More sets will certainly provide a greater rate of hypertrophy, within reason. To begin, you need to estimate your “one-repetition maximum” (1-RM). This will be the maximum weight you can overcome to complete one repetition. Certainly it is not recommended that you try to determine your 1-RM by experimenting with heavy weights if you are just getting started. You can experiment with light weights and determine the best weight for an exercise (for example, shoulder press, bench press, curls) with which you are able to do about five to ten repetitions. This should be about 80 to 85 percent of your 1-RM. Your goal for muscle development is to do three to four sets of 8 to 12 repetitions before experiencing muscle fatigue.
Should You Increase Resistance over Time?
As you continue to train that muscle, over time you will find it necessary to increase the level of resistance to continue to make progress. This is evident as the number of repetitions you can do before fatiguing exceeds the recommended range for muscle development and is an indicator that your muscle is adapting and getting stronger. Initially, some of this adaptation is merely your muscle becoming more efficient in the exercise. However, overall most of the improvement in performance will be because the muscle is developing more contraction machinery and as a result getting bigger. Try increasing the amount of resistance by 10 percent and determine if that puts you back in the muscle development repetition range.
How Much Rest Do You Need In-Between Sets Within the Same Workouts?
When you engage in resistance training you are making great demands on your muscles. Therefore, the worked muscle should be given adequate time to rest and recover after a set of repetitions. Depending on the intensity of the set, muscle will need about 1 to 3 minutes to rest between sets to recover. During a set the limited stores of ATP and creatine phosphate are rapidly depleted. Giving muscle a break between sets allows for regeneration of ATP and creatine phosphate. The period of rest between sets also allows for the blood to bring more nutrients and oxygen and remove waste and at the same time also. As muscle contracts it temporarily pinches blood vessels and hinders blood flow within that muscle. This not only decreases nutrient and oxygen delivery to working muscle fibers but also decreases the removal of waste such as lactate and carbon dioxide.

How Much Rest Do You Need Between Workouts?
If a muscle is trained hard it is generally recommended to rest a muscle for at least 48 hours before working the same muscle again. This allows muscle to recover and adapt. Often people will train the same muscles on Mondays, Wednesdays, and Fridays or Tuesdays, Thursdays, and Saturdays and rest the muscle in-between. If a muscle is trained very hard in a given workout by doing extra sets, that individual may train that muscle only two times a week or every 5 days or even once a week. Rest is necessary between resistance exercise to allow muscle to repair, recover, and adapt.
What Does It Take for Muscle to Recover and Repair After a Workout?
Recovery and repair processes include those that prepare muscle to perform efficiently again. This includes: reducing the lactate level of the muscle fibers worked, which may not take that long; repleting glycogen stores, which can take hours; and repairing cellular damage in the trained muscle fibers, which can also take hours or even a day or so. Adaptation, on the other hand, refers to those processes designed to allow muscle to be better prepared to work again. This will include a net production of muscle proteins that will support contraction the next time around. As muscle cells accumulate more protein, they will also accumulate more water. Therefore, much of muscle hypertrophy is protein and water. In addition, connective tissue providing integrity and support to the overloaded muscle will be enhanced as well.
Does Our Energy Expenditure Increase Due to Weight Training?
The increased energy demand of weight training depends on the intensity level and duration of a workout coupled with the energy needed for recovery and adaptation. The energy needed for a workout may be along the order of 5 to 10 calories per minute while recovery and adaptation may demand 100 to 300 calories over the next day. This additional energy expended should be calculated into your total energy expenditure. The predominant fuel powering weight training is carbohydrate, derived mostly from muscle glycogen stores and secondarily fat from fat tissue and within muscle tissue itself. One of the strongest influences will be epinephrine, which is released from the adrenal glands during intense training. Epinephrine will promote the breakdown of glycogen and fat stores, making those energy sources available to working muscle. On the other hand, both fat and carbohydrate fuel adaptive processes over the next few hours up to the next day or so. The most important factors dictating fuel preference will be meals and corresponding fluctuations in insulin and glucagon levels.
How Much Energy Should Be Eaten to Make the Body More Lean and Muscular?
To become more muscular and lean, people combine weight training with dietary control. In addition, integrating aerobic training will certainly be beneficial. It’s not important not to drastically restrict energy intake, if at all. Drastic energy restriction can place an extra demand upon skeletal muscle to provide amino acids for energy, thus counteracting resistance training to some degree. Thus drastic energy restriction and weight training may create a futile cycle as muscle breakdown contradicts muscle hypertrophy. If you are at a fairly comfortable body size but you want to increase your muscularity and leanness, you will be best served by eating enough energy to meet your expenditure. That would include the energy expended due to exercise training while also choosing foods higher in healthier carbohydrates and protein versus fat. The major thrust of your efforts should focus on the change in body composition, not necessarily body weight. In fact, as you add skeletal muscle, it is possible that you will gain weight. For heavier people with a higher percentage of body fat who wish to become leaner, they can begin by estimating their daily calorie needs and then restrict energy intake by 10 to 20 percent. This is easily done by substituting foods with a greater percentage of energy from carbohydrate and protein versus fat. Furthermore, engaging in regular aerobic activities will be of benefit, as discussed shortly.

How Much Protein Is Needed During Weight Training?
Protein is the major nonwater component of skeletal muscle accounting for more than 20 percent of its total weight and more than 80 percent of water-free weight. Logically, if you want to build more muscle, you need to eat more protein beyond the needs for normal maintenance. People who engage in serious weight-training athletes may benefit most from a protein intake of 1.4 to 1.75 grams per kilogram of their body weight or more. This translates to about 1.75 to 2.25 times the RDA for protein. Several research studies using protein intakes above this level have failed to show additional benefit (more muscle gain). Furthermore, the intensity and extent to which individuals train will dictate where they may fall within these ranges for protein recommendations.

Serious weight training can double daily protein requirements in order to repair and adapt muscle tissue.

Is the Timing of Protein Consumption Important to Developing Muscle Size and Strength?
The importance of protein to muscle development has been known for decades. However, recently “protein timing” has become of greater interest. Sophisticated research techniques have allowed for an understanding of the importance of consuming protein around a workout to maximize gains in muscle development. As discussed above, a resistance training sessions results in a simultaneous increase in protein synthesis and breakdown. Consuming protein either just before or immediately after a workout helps maximize muscle protein synthesis and along with carbohydrate to minimize muscle protein breakdown, which combined will lead to better results. Furthermore, protein is needed throughout the day to support on-going repair and adaptation, which can last as long as a day.
Are Certain Proteins Better Than Others for Building Muscle Size and Strength?
Protein from animals is rich in essential amino acids and in particular branched-chained amino acids. This includes red meat, poultry (meat and eggs), fish, and milk (dairy). Soy is also a good source of essential amino acids. Any or combinations of these protein sources consumed before or after a workout will support muscle development. On the other hand, supplement manufacturers target single-protein ingredients such as whey protein isolate or a blend of protein ingredients to create a more strategic muscle development food. Furthermore, protein fractions from milk namely, whey protein isolate, whey protein concentrate, and casein can be used strategically as whey is more rapidly digested and absorbed than casein. This has led to the idea of “fast” and “slow” protein, which is like a time-release system. Whey also seems to be a little more advantageous in supporting muscle development processes than soy, which is one reason why whey is the principal protein ingredient in many bars and shakes and soy is either absent or contributes less to the formulation.

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