In 2023, Tigist Assefa of Ethiopia set a new record with a time of 2 hours, 11 minutes, and 53 seconds. Scientists, trainers, and athletes alike have wondered about the extent to which muscle structure and function contribute to success in athletes such as Assefa. What makes elite distance runners so good? Are their muscles somehow different from those of less successful athletes and non-athletes? Predict the effect of training for a marathon on the number of muscle cells in the gastrocnemius. Explain.

Verified step by step guidance

1. Understand the muscle types: Recognize that the human body has different types of muscle fibers, primarily slow-twitch (Type I) and fast-twitch (Type II). Slow-twitch fibers are more efficient at using oxygen to generate more fuel (known as ATP) for continuous, extended muscle contractions over a long time. Fast-twitch fibers are better at generating short bursts of strength or speed.
2. Identify the muscle in question: The gastrocnemius muscle, part of the calf, is crucial for running as it helps in plantar flexing the foot at the ankle joint and flexing the leg at the knee joint. This muscle contains both types of fibers, but the proportion can vary.
3. Consider the effects of endurance training: Training for a marathon typically involves long, sustained periods of running, which primarily engages and develops slow-twitch muscle fibers. This type of training enhances the efficiency and endurance of these fibers.
4. Predict changes in muscle cells: While the total number of muscle cells (muscle fibers) generally remains constant, the size and efficiency of the existing muscle fibers can increase. Endurance training like marathon running can lead to physiological changes in the muscle fibers, such as increased mitochondrial density, increased capillary growth, and changes in enzyme activity, which improve aerobic capacity.
5. Summarize the effect on muscle cells: Training for a marathon would not necessarily increase the number of muscle cells in the gastrocnemius but would enhance the functionality and endurance capacity of the existing slow-twitch muscle fibers.