Like any other component of fitness, muscle growth takes time, solid nutrition, and thoughtful and consistent training practices aimed at developing muscle hypertrophy. How quickly those changes are seen varies for each individual. No two bodies are exactly the same and, therefore, no two people will build strength and size at equal rates.

Factors Influencing Muscle Development

To understand the most effective methods for adding muscle size and growth, it’s important to first recognize the factors that influence muscle-mass development. The two categories of factors that play a role in the process of muscle development are the genotype (genetic code of an individual) and the phenotype (observable physical characteristics of an individual). Sub-factors related to genotype are sex and genetic make-up. Sub-factors related to phenotype, or the interaction of genotype and environment, include:

• Age at which training began
• Training load
• Training duration
• Training frequency and recovery from training
• Training history/physical activity during childhood
• Carbohydrate and protein intake
• Caloric intake
• Hydration
• Hormonal influences

We cannot change or make modifications to the genotype factors (genetics and sex). We also cannot control shifts in hormones as we age (without pharmaceutical and/or medical intervention). We can, however, determine when training starts, the overall training load, duration and frequency, and daily dietary habits.

Some people possess a natural predisposition to building large amounts of muscle mass, which is determined by their genotype (or genetic blueprint inherent to their DNA). Others do not possess that same natural ability. Genetics dictate the upper limit for how much muscle mass is attainable per individual. In other words, how much and how quickly muscle grows is largely influenced by something you are unable to alter—your genes. For example, a 20-year-old male with strong genetic potential and a large percentage of fast-twitch muscle fibers (those that respond to growth the easiest) could gain lean mass at a rate of 2 pounds per month. Over time, that rate will decrease as his lifting experience matures, his hormonal profile changes and his body adapts. By contrast, someone with a different genetic profile and body type may only be able to build muscle at a rate of a one-half pound per month.

While the rate at which a person will build muscle mass is not predictable, with the right diet and proper training regimen everyone has the ability to add strength and mass.

How Strength and Mass Increase

Strength training results in specific physiological adaptations. During the initial phase of a strength-training program, noticeable gains are made due to something called neural adaptability, which is an increase in the recruitment of motor units. As the nervous system becomes more efficient and recruiting more motor units, more force is produced. These initial adaptations are often falsely interpreted as muscle size increases.

With continuous and strategic training, however, the body continues to adapt and the development of new muscle tissue increases. This is when mass or muscle hypertrophy is observed. However, individual genetics still determines how responsive muscle tissue will be to strength training.

With that said, the average time to see this adaptation ranges anywhere from three to six months.

What Type of Program is Best

ACE recommends the following type of program for specifically focusing on building muscle mass. It is important to note that research has not identified the optimal training tempo for adding size and strength.

Source: ACE Personal Trainer Manual, 5^th edition (2014).

To aid in further improving body composition, try mixing up the routine and doing a four-day split or a circuit workout (circuits have added aerobic benefits, too). Add a couple of days of high-intensity interval training (HIIT) cardio to burn additional calories. As you notice the weights become easier to lift, increase the resistance and keep challenging your body to see optimal gains.

Whatever type of routine you follow, make sure you focus on  movements that use multiple muscle groups (squats, bench press, deadlift, lunges, rows, etc.). Further, be sure to eat a balanced diet high in lean proteins, veggies, fruits and whole grains. Stay hydrated and reduce overall intake of added sugar and simple carbohydrates.