Final answer:
To obtain sharply defined muscles, the two strategies needed are increasing muscle hypertrophy through progressive resistance exercise and reducing body fat to showcase muscle definition.
Step-by-step explanation:
To obtain sharply defined muscles, two main strategies are necessary: muscle hypertrophy and body fat reduction. Muscle hypertrophy refers to increasing the size of muscle fibers through strength training exercises, such as weight lifting. For hypertrophy to occur, it is important to continually increase the intensity of exercises by lifting heavier weights or increasing resistance, as our muscles adapt and become stronger. Additionally, to showcase muscle definition, one must also reduce body fat through a combination of diet and cardiovascular exercise.
Low body fat allows the muscles to be more visible and appear more defined. It is important to note that muscle fibers can only contract; they cannot actively extend, which is why pairs of muscles must work in opposition to perform movements like bending and extending the arm at the elbow. Other body movements that require opposing muscle pairs include walking, where the quadriceps and hamstrings work in opposition, and gripping, where the forearm flexors and extensors work against each other.
Muscle strength is also an essential factor for athletes like tennis players who need to generate force for their movements. Increasing myofibrils and sarcomeres within each muscle fiber results in greater mass and strength. In contrast, decreased muscle use or certain diseases can result in muscle atrophy, where muscles weaken and lose mass. To avoid atrophy and promote hypertrophy, regular and progressively more challenging resistance exercise is key.
The function and movement of intrinsic skeletal muscles, such as those in the back, neck, thorax, and abdomen, are also crucial for core strength and posture, further enhancing muscle definition.