Is the limit in the body’s physiology or in the mind, or in a combination of the two? (Mine is surely in the mind, I haven’t gone close to limits of my body for running, swimming or cycling.) An exploration of research on limits of endurance performance and how to stretch them. I really enjoyed the middle and last section of the book—covering various physiological elements affecting the body, and the research on identifying and stimulating areas of the brain to stretch performance.
A well written primer of our understanding of specific genes and their impact on sports performance—from natural physical traits (height, strength, achilles, calf size, etc) to training ability to pain thresholds and more. David tries to balance the nature (genes) vs nurture (environmental) factors. He also points out, repeatedly, that our understanding of impact of specific genes, specially in combinations, is still very incomplete.
Another takeaway, for me, is that much of what our understanding of these genes reveals is what separates the (say) Olympians from everyday people. The performance differences amongst the people at the top is too small to be explained by our current understanding of genes.
Finally, even at the very top, there are multiple paths to get there. The story of two high jumpers illustrated this well.