These factors cannot be changed and may enhance/ inhibit one's ability to improve.
1. Gender - males will have greater gains in muscle mass and relative strength gains compared to females and also relative strength gains, but not absolute.
2. Muscle Attachments - a muscle will attach at two points - the origin and insertion - on two bony levers. These points of attachment will be the same for everyone. The difference is the angle of attachment of the muscle. A better angle of attachment could result in better leverage from the bone thus allowing greater weight to be lifted.
3. Number of Muscle Fibers - since hypertrophy (increase in size) is due to an increase in the diameter of existing fibers, then the greater number of muscle fibers genetically inherited increases the chance of greater hypertrophy.
4. Proportion of of Fast Twitch (FT) to Slow Twitch (ST) Muscle Fibers - Motor units contain muscle fibers that have different metabolic or functional capabilities. Some are better equipped biochemically and physiologically to work aerobically and others to work anaerobically. Researchers are identifying more and more distinct fibers as time goes by; however, the two major categories of muscle fibers fall into a slow or fast twitch category. Slow Twitch fibers are better equipped for endurance (aerobic) while Fast Twitch fibers are better equipped for non-endurance (non-endurance/anaerobic/power). Research has shown that FT fibers can hypertrophy much more than ST so a muscle's potential to grow might be determined by its ratio of FT to ST. These ratios can also serve as an advantage for many athletes who perform in a specific sport like a sprinter who has a high amount of FT fibers in his/her calves.
3. Level of Aspiration
Lifestyle and Training Factors
1. weight training program (consistency)
2. nutritional status/diet
3. rest/sleep habits
4. performance enhancement aids
1. acute soreness - pain occurs immediately following the exercise and is thought to be associated with a lack of adequate blood flow to the active muscle (ischemia)
2. delayed soreness - pain that occurs 24-48 hours after an exercise session has stopped. The degree of soreness is usually related to the type of contractions performed (eccentric movements can lead to more soreness)