🔹 DeMoor Store: https://www.demoorstore.com/ Get your gear today DGR! 🔹 Running Warehouse ALL Gear, use this link to buy any running gear you need: https://www.runningwarehouse.com/?from=demoor 🔹 Running Warehouse Clearance: https://www.runningwarehouse.com/salelanding.html?from=demoor Physiological Adaptations During the Aerobic Base Building Phase: Several key physiological changes take place during the aerobic base building phase, all of which contribute to the runner’s improved performance on race day. These changes include the expansion of red blood cell volume, increased mitochondrial density, the growth of capillary beds, and improvements in the suppleness of the lower legs. Red Blood Cells: One of the most critical physiological adaptations during the aerobic base building phase is the increase in red blood cell (RBC) volume. RBCs are responsible for transporting oxygen from the lungs to the muscles, and an increase in RBC count allows the body to deliver more oxygen to working muscles during exercise. This is particularly important for long-distance runners, as an increased ability to transport oxygen can delay the onset of fatigue and improve endurance performance. Lydiard’s training emphasized aerobic running as a means of stimulating the production of red blood cells. Research has shown that long, steady-state runs, as prescribed by Lydiard, can increase hematocrit levels (the percentage of blood volume composed of red blood cells), thereby enhancing an athlete’s capacity for endurance. Mitochondria: Mitochondria, often referred to as the "powerhouses" of the cell, play a key role in energy production during aerobic exercise. As runners engage in high-volume aerobic training, the number and size of mitochondria in muscle fibers increase, allowing for more efficient energy production from fat and carbohydrates. This adaptation enables runners to maintain higher intensities over longer periods of time. Lydiard’s base training methodology, which involved running at a low to moderate intensity for extended periods, is an ideal stimulus for mitochondrial growth. These increased mitochondria provide the muscles with greater energy efficiency, ultimately contributing to better race-day performance. Capillary Beds: Another critical adaptation during the aerobic base building phase is the growth of capillary beds in muscle tissue. Capillaries are the smallest blood vessels in the body, and their role is to deliver oxygen and nutrients directly to muscle fibers. Increased capillary density improves the muscles’ ability to extract oxygen from the blood, facilitating better endurance and faster recovery. Lydiard’s emphasis on long, steady-paced runs allows for the expansion of capillaries within muscle tissue. This enhanced network of capillaries ensures that the working muscles are adequately supplied with oxygen during prolonged efforts, delaying fatigue and enhancing performance. Suppleness in the Lower Leg: During the aerobic base building phase, runners also experience improvements in the suppleness and elasticity of the lower legs, including the calves, Achilles tendon, and surrounding tissues. This is an often-overlooked but essential adaptation that improves running efficiency and reduces the risk of injury. As runners accumulate high training volumes, the repeated loading and unloading of the lower legs leads to the development of more resilient connective tissues. This increased suppleness allows for a more efficient stride and reduces the likelihood of overuse injuries, such as Achilles tendinopathy or calf strains. Lydiard understood the importance of this adaptation and often prescribed a high volume of aerobic running to stimulate tissue adaptation while maintaining a smooth, efficient running form. Conclusion: The aerobic base building phase of a half marathon training block is a critical time for runners preparing for the Jersey City Half Marathon or any similar event. During this phase, a runner’s cardiovascular system, muscle efficiency, and overall endurance are developed to ensure that the body is primed for the more intense training efforts that follow. By adopting the principles espoused by Arthur Lydiard and further refined by Mark Wetmore, runners can achieve significant physiological adaptations that enable them to perform at their best on race day. These adaptations include increased red blood cell volume, enhanced mitochondrial density, expanded capillary networks, and improved suppleness in the lower leg, all of which contribute to a more efficient, sustainable, and injury-resistant running performance. As such, the aerobic base building phase is an essential foundation for success in any half marathon training program.