Exercise Physiology and Performance
Performance questions test energy systems and their limiting factors. The phosphagen (ATP-CP) system fuels seconds-long bursts; glycolysis dominates short high-intensity efforts and produces lactate; oxidative phosphorylation supports sustained work. Understand VO2max as the product of cardiac output and arteriovenous oxygen difference, and that endurance training increases stroke volume and mitochondrial density. Know the lactate threshold concept - the intensity above which lactate accumulates faster than clearance - and that training raises the threshold, improving sustainable pace.
Traps: equating lactate with "fatigue toxin" (it is a fuel and a signaling molecule); confusing heat acclimatization timelines (benefits accrue over roughly 1–2 weeks); and mixing up concentric versus eccentric contraction energetics (eccentric costs less oxygen for the same force). Know the principles of training: overload, specificity, reversibility, and periodization. Recognize that altitude increases ventilation and hemoglobin over weeks but acutely reduces plasma volume and performance.
Rule of thumb: "match the fuel system to the event duration." Worked example: a 400-meter sprinter's performance is limited mainly by anaerobic capacity and lactate tolerance, so training emphasizes short intervals above race pace rather than long slow distance; a marathoner's limiter is sustainable oxygen delivery and fuel, so threshold and long runs dominate.