Final answer:
O2 supplementation on the sidelines doesn't help football players recover from a 99-yard touchdown run due to factors such as the accumulation of carbon dioxide and the need for various physiological processes in recovery.
Step-by-step explanation:
Football players don't recover from a 99-yard touchdown run with O2 supplementation on the sidelines because their fatigue is not solely due to lack of oxygen. During intense physical activity, the muscles require more oxygen and produce more carbon dioxide, causing an increased demand for respiratory gas exchange. While supplementing with oxygen can help meet the increased oxygen demand, it doesn't address the accumulation of carbon dioxide and the resulting metabolic waste products in the muscles.
Additionally, recovery from intense exercise involves various physiological processes, including replenishing depleted energy stores, repairing muscle tissue damage, and removing metabolic waste products. While O2 supplementation may improve oxygen delivery to the muscles, it doesn't directly aid these recovery processes.
Instead, post-exercise strategies such as proper nutrition, hydration, rest, and active recovery exercises are crucial for football players to recover effectively.