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Strength factors


Why does one person develop strength and muscle faster than another when he or she is performing the same exercises in the same training program? The following factors affect every person's ability to achieve strength and muscle development, and we have little or no control over most of them.

Type of muscle fiber

We have little control over the types of our muscles. There are two basic types of muscle fibers:
  • Type I (slow-twitch).  Slow-twitch muscle fibers are best used for cardiovascular (aerobic) activities where more oxygen is available in the bloodstream than is needed to generate power. They produce small levels of force for long periods and thus are better suited for endurance activities. 
  • Type II (fast-twitch). Fast-twitch fibers are best used for anaerobic activities where the muscles require more oxygen than is available in the bloodstream. They produce high levels of force for short periods and are best suited for power activities such as weightlifting.
The amount of each type of muscle in your body is mostly determined by genetics although there is evidence that the ratio between the two types can be changed through physical training.

Most men and women have an equal combination of both slow-twitch and fast-twitch fibers. However, some people have a high percentage of slow-twitch fibers that enhance their performance in endurance activities, such as long-distance runners. Most world-class marathon runners have a remarkably high amount of slow-twitch fibers. Conversely, the fastest sprinters have relatively more fast-twitch muscle fibers.

Although both fiber types may be enhanced by strength training exercises, fast-twitch muscle types tend to experience greater increases in muscle size and strength. Thus, fast-twitch muscle fibers may obtain greater and/or faster results from strength training than do slow muscle fibers.


We have no control over our age. Studies show that people of all ages can increase their muscle size and strength through a safe and effective strength training program. However, the rate of strength and muscle gain appears to be greater from ages 10-20, the years of rapid growth and development. After reaching normal physical maturity, muscular improvements usually do not come as quickly.


We have little control over our gender. Gender does not affect the quality of our muscles, but it does influence the quantity. Although men's and women's muscle tissue are characteristically the same, men generally have more muscle tissue than women do because muscle size is increased by the presence of testosterone, the male sex hormone. The larger the muscles, the stronger the person; therefore, most men are stronger than most women.

Limb and muscle length

We have no control over the length of our limbs and thus the length of our muscles. Persons with short limbs tend to be able to lift more weight because they can take better advantage of the benefits of leverage. Since our muscles are attached to our limbs, the length of our limbs determines the length of our muscles. Persons with relatively long muscles have greater potential for developing size and strength than persons with relatively short muscles. So, there are strength benefits to having both short or long limbs and muscles.

Point of tendon insertion

We have no control over the point where the tendons of our muscles attach to our limbs, which is called the tendon insertion point. A muscle’s strength is influenced by its points of tendon insertion. For example, for two people with the same arm and muscle length, if one person's biceps tendon attaches to the forearm farther from the elbow joint than the other person's, that person will have a biomechanical advantage and be able to lift more weight than the other in biceps exercises such as the biceps curl.

Other factors

All these factors affect our ability to gain strength and muscle development through training. However, the most influential factor in achieving good results is using a slow, controlled lifting movement and lifting to the point of muscle fatigue.

Since this intensive muscle training causes microtears in the muscles, you must give your muscles enough resting time between training sessions for them to heal. Overtraining occurs when you do not allow your muscles enough rest and you are training using too many sets and exercises for each muscle group.

Another mistake people make is doing the same exercises repeatedly even after they have reached a plateau. Any time you stop gaining strength or muscle size or you, it is crucial that you change your exercise regime. Then you will experience new gains strength and muscle size.

Although genetics plays a role in your health and appearance, they do not determine how often or well you train. Even if you are born with a genetic predisposition to being overweight or weak, the way you live will ultimately determine whether you become fit and strong or fat and weak.

Weightlifting provides many important benefits that cannot be achieved by any other exercise or activity. Physiologically, the benefits of consistent strength training include an increase in muscle size and tone, increased muscle strength, and increases in tendon, bone, and ligament strength. Strength-training also improves psychological health by increasing self-esteem, confidence, and self-worth. Research has shown that weightlifting not only causes your body to burn more calories during a weightlifting session but that the increase in calorie burning lasts for hours after the session ends.

If you understand and accept your body, you will be able to work with it, not against it. Everyone can improve their strength, appearance, and performance level by consistently implementing an effective strength training program.


Tackett, C. (2017). Factors Affecting Strength. Online:

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