Although related, muscular strength and size depend on different training protocols for enhancement. For instance, large-muscled bodybuilders are likely less strong than smaller-muscled Olympic weightlifters, or strength athletes, due to differences in muscle physiology and training programs. One trains for size while the other trains for strength. Understanding the difference enables proper program design for your intended fitness outcomes.
Variables of Muscular Fitness
Variables of muscular fitness include strength, size and endurance Strength defines your ability to create maximal force during one contraction, size relates to muscle volume and appearance and endurance dictates your ability to sustain a specific muscular activity over time.. Neuromuscular control, the communication between your brain and muscles, influences all variables in different ways.
Strength Training Programs
A successful strength training program incorporates up to five sets, of one to eight repetitions, using heavy loads, as defined by the American Council on Exercise. Your one-repetition maximum represents the heaviest load you can lift successfully, one time, for a given exercise. ACE defines a heavy load as equaling 80 to 100 percent of your one-rep maximum. Strength training programs develop your ability to activate current muscle mass, while promoting slight size increases.
An efficient muscle-building routine requires one to six sets, of eight to 12 repetitions, using 70 to 80 percent of your one-repetition maximum, as prescribed by ACE. Moderate loads enable greater repetitions and increase training volume. Training volume is calculated by multiplying repetitions, sets and load lifted. Muscle-building programs focus on resistance-training induced intramuscular damage which results in increased fiber diameter and subsequent muscle growth after recovery occurs.
Types of Muscle Fibers
Each muscle contains various ratios of specialized muscle fibers. Slow-twitch muscle fibers perform low-intensity, long duration actions, such as walking, while fast-twitch fibers perform high-intensity, ballistic actions, such as jumping. Although both fibers contribute to all actions, intensity dictates which fiber type dominates force production for a given movement. Fast-twitch fibers influence strength and size in different ways. For instance, fast-twitch fibers contain greater capacity for growth and greatly influence force production.
Why Neuromuscular Control Matters
Resistance training improves your ability to activate muscle fibers, as stated by the National Strength and Conditioning Association. Although it is impossible to activate all fibers in a given muscle at once, a successful strength training program brings you closer to that goal. Lifting heavy loads supports greater fiber activation. On the other hand, muscle growth relies on activation and adaptation of fast-twitch fibers for maximal size enhancement. Moderate loading continues to activate fast-twitch fibers while allowing enough repetitions for intramuscular damage. Consult a doctor before you start a weightlifting program.
- “American Council on Exercise Personal Trainer Manual”; American Council on Exercise; 2003
- "Essentials of Strength Training and Conditioning"; National Strength and Conditioning Association; 2000