Final answer:
a) Constant-resistance machines adjust resistance automatically during exercise. The main difference is that constant-resistance machines maintain a fixed resistance level throughout an exercise, while variable-resistance machines adjust the resistance to match the muscle's strength curve. Variable-resistance machines can provide a more tailored workout that potentially increases in difficulty, whereas constant-resistance machines use a steady resistance that users have to manually adjust to increase intensity.
Step-by-step explanation:
When comparing constant-resistance and variable-resistance dynamic exercise machines, we're exploring how each type of equipment maintains resistance during workouts. Constant-resistance machines are defined by their ability to maintain the same level of resistance throughout the entire range of motion. This means that the resistance does not change as the user progresses through the exercise. On the other hand, variable-resistance machines are designed to alter the resistance level during the range of motion to match the natural strength curve of the muscles being worked; this typically involves differing levels of resistance at different points of the exercise.For example, in the context of weight lifting for effective strength training, simply continuing with the same weight does not lead to increased muscle size or strength. In order to see improvements, the intensity of the exercise must be gradually increased, which can involve a progression from lesser to greater resistance.
Variable-resistance machines aim to accommodate this principle by providing a slight increase in resistance or a huge increase in resistance at different stages of the motion, contingent on the machine's design. Conversely, constant-resistance machines may require manual adjustments to change the weight or resistance level, as it remains fixed during the exercise.An analogy can be drawn to electrical circuits: increasing resistance may affect how rapidly a circuit reaches a steady state. Similarly, in exercise equipment, the way resistance is applied or adjusted can influence training effectiveness and muscle adaptation. The primary difference lies in the adaptive challenge posed by variable-resistance machines compared to the static challenge of constant-resistance machines.