Chapter 23 — Exercises

Three tiers. 🔄 marks retrieval; 🪞 reflection. ⚠️ Part V's register: more calculation, fewer adjudications.**

Tier 1 — Recall and Comprehension

R1. Give §23.1's hierarchy in order, with the verdict for each level. ⚠️ Which two get the most attention, and where do they rank?

R2. Define energy availability and give the formula. ⚠️ What are the two commonly cited reference figures, and what do they mean?

R3. Name five reasons sports nutrition evidence is unusually good.

R4. Give the carbohydrate table from §23.3 — all four training loads with their g/kg ranges.

R5. ⚠️ Why can't muscle glycogen be shared between muscles or exported to the blood? What enzyme is missing?

R6. Distinguish "the wall" from "the bonk" — different store, different symptom, same fix.

R7. Give §23.5's four duration bands with their carbohydrate recommendations. ⚠️ Why does the 60 g/hour ceiling exist, and how is it exceeded?

R8. What is a carbohydrate mouth rinse and why does it work?

R9. State the protein targets for athletes, per meal and per day, and during energy restriction.

R10. ⚠️ What did the race-walker study find about LCHF, and what is the mechanism?

R11. Why was programmed drinking replaced by drink-to-thirst?

R12. ⚠️ Name the five supplements, their doses, and what each is for. Which two share a duration window, and why?

R13. Give the four R's of recovery in order. ⚠️ Which is not a nutrition intervention and beats all of them?

R14. ⚠️ What is strict liability in anti-doping? What follows practically?

R15. ⚠️ Give §23.11's two limits on this chapter's evidence base.

Tier 2 — Application

A1. 🔄 Calculate. A 68 kg triathlete trains 12 hours/week, with two sessions over 2.5 hours.

a) Carbohydrate target range, g/day? b) Protein target range, g/day, and per meal? c) In-session carbohydrate for the 2.5-hour sessions, g/hour? d) ⚠️ What form must that carbohydrate take to reach the top of the range, and why?

A2. The wall, quantified. A 58 kg runner with ~450 g total glycogen runs a marathon costing ~2,550 kcal.

a) How many kcal are stored? b) ⚠️ What's the deficit? c) At 60 g/hour over 3.5 hours, how much does in-race fuelling close it? d) What else has to happen to close the rest?

A3. Match the athlete to the answer. For each, state the single highest-yield change:

a) A marathoner eating 3.5 g/kg carbohydrate, training 100 km/week b) A lifter taking a post-workout shake within 10 minutes, eating 90 g protein/day at 85 kg c) A recreational runner taking a gel during every 45-minute run d) A rower with a bone stress injury, irregular periods, and a 2 km PB that's stalled e) A cyclist who cramps in hot events and drinks plain water

A4. Design the in-race plan for a 4-hour cycling event in 28°C, for a 75 kg rider who is a heavy salty sweater.

A5. ⚠️ The recreational correction. Take §23.14's hard-training-day template and rewrite it for someone training 4 hours/week at moderate intensity.

What changes, what stays, and what gets deleted entirely?

A6. Grade the supplement stack. An athlete takes: whey protein, BCAAs, creatine, a pre-workout, glutamine, a multivitamin, beetroot juice, and an electrolyte sachet daily.

a) ⚠️ Which items have evidence at the doses likely present? b) Which are redundant given the others? c) Estimate the annual cost, and the annual cost of the evidenced subset. d) ⚠️ If they're drug-tested, which items are highest risk and why?

Tier 3 — Analysis and Synthesis

S1. The hierarchy inverted. §23.1 says attention runs almost exactly opposite to importance.

a) Give three structural reasons why. ⚠️ At least one should be commercial and at least one should not be. b) How would you design a coaching intake form that forces rows 1–4 to be addressed before rows 6–7 are discussed? c) ⚠️ Chapter 21 §21.14b said "who profits?" is necessary and not sufficient. Apply it here.

S2. Train-low, adjudicated. §23.4 gives it 🟡 with robust signalling and inconsistent outcomes.

a) Why might a real molecular adaptation fail to produce a performance benefit? Give three mechanisms. b) ⚠️ Design the trial that would settle it, including how you'd separate train-low from chronic under-fuelling. c) What's your dropout estimate, and what does that do to your interpretation?

S3. ⚠️ The male literature problem. §23.11 concedes the evidence base is substantially male.

a) Which recommendations in this chapter do you expect to transfer, and which not? Justify each. b) ⚠️ What would it take to fix this? Be specific about cost, recruitment and design. c) Does the same problem exist elsewhere in this book? Name two chapters.

S4. Body composition, honestly. §23.13 holds two things simultaneously: composition affects performance in some sports, and its pursuit causes documented harm.

a) ⚠️ Write the policy you'd want for a national youth squad in a weight-sensitive sport. b) What can a coach do tomorrow at zero cost? (The chapter names one.) c) ⚠️ How would you know if your policy was working? What would you measure, and what would you refuse to measure?

S5. Effect sizes and who buys them. §23.9's five are worth roughly 1–3%.

a) ⚠️ Explain why that makes them essential at elite level and nearly pointless recreationally. b) Construct the marketing message that would be honest. Why doesn't it exist? c) ⚠️ Nitrate's effect shrinks in highly trained athletes — the inverse of who buys it. Find one other product in this book with the same inversion.

S6. 🔄 Devi's arc. She appears in Chapters 14, 21 and 23.

a) List every intervention across the three chapters and rank them by contribution to the final outcome. b) ⚠️ Which single one would you have done first, knowing nothing else? c) Her fitness didn't change in the final block. ⚠️ What does that imply about how much underperformance in endurance sport is nutritional rather than physiological? How would you test that claim at scale?

🪞 Reflection

M1. ⚠️ Which row of §23.1's hierarchy have you been working on? Be honest — and if you don't train, answer it about whatever you do optimize.

M2. §23.13 says most athletes trying to get lighter are past the peak, not short of it. ⚠️ Has that ever been true of you? What made you think otherwise at the time?

M3. ⚠️ Devi called it "the wall" and assumed it was a mental problem, because that's what everyone told her. Where else have you been given a psychological explanation for a physiological problem?

M4. The chapter says sleep beats every nutrition intervention in it. ⚠️ Do you act as though that's true? What would change if you did?

M5. 🔄 ⚠️ Part V opens with a chapter that has six ✅ verdicts, after six chapters that barely managed that between them. Does the better evidence make you more inclined to act? Should the strength of evidence change your behaviour, or only your confidence?