A strength athlete eats 40g of protein immediately after training but avoids carbohydrates to stay lean. Compared to eating protein plus carbohydrates, how will this affect muscle recovery?
ARecovery will be the same — protein alone fully drives muscle protein synthesis
BRecovery will be faster — avoiding carbs reduces post-workout inflammation
CRecovery will be slower — carbohydrates trigger an insulin response that helps drive amino acids into muscle cells
DRecovery will be slower only if the athlete was already glycogen-depleted before training
Carbohydrates after training serve two functions: they replenish depleted glycogen stores AND stimulate insulin release. Insulin acts as a transport signal that drives amino acids into muscle cells, amplifying muscle protein synthesis. Protein alone provides the raw materials but misses this insulin-mediated uptake enhancement. The 'protein only' strategy is less effective than the research supports — the combination of protein plus carbohydrates consistently outperforms either alone for recovery.
Question 2 Multiple Choice
An endurance runner 'hits the wall' at mile 20 of a marathon, experiencing sudden severe fatigue and inability to maintain pace despite feeling fine earlier. The most likely physiological cause is:
AAcute dehydration reducing blood volume and oxygen delivery
BDepletion of muscle glycogen stores, removing the primary fuel for sustained moderate-to-intense exercise
CExcess dietary fat slowing digestion and impairing nutrient absorption during the race
DMuscle protein breakdown exceeding synthesis rates as the body shifts to protein catabolism
Glycogen is the dominant fuel for moderate-to-intense sustained exercise. When glycogen runs out, the body cannot maintain the pace — this is 'bonking' or 'hitting the wall.' The fix is glycogen loading in the days before the race and strategic carbohydrate intake during it. Dehydration (option a) impairs performance gradually; the sudden 'wall' characteristic is the glycogen-depletion signature. This is why pre-workout meals specifically emphasize complex carbohydrates to top off glycogen stores.
Question 3 True / False
High protein intake is the single most important dietary factor for improving athletic performance, because muscle is made of protein and exercise breaks down muscle tissue.
TTrue
FFalse
Answer: False
For most athletes and most types of exercise, carbohydrate availability (glycogen stores) is the primary limiting factor in performance — not protein. Protein is critical for muscle repair and growth, but exercise performance depends on having adequate fuel during the effort. Severe protein deficiency impairs recovery, but athletes in developed countries rarely lack protein; they are far more likely to be under-fueled with carbohydrates or dehydrated. The 'protein first' framing is one of the most common misconceptions in sports nutrition.
Question 4 True / False
Drinking water alone is sufficient for hydration during extended high-intensity exercise lasting more than one hour.
TTrue
FFalse
Answer: False
Sweat contains significant electrolytes — primarily sodium, but also potassium and magnesium. Drinking plain water replaces volume but not electrolytes. For extended high-intensity efforts, drinking water alone can actually dilute remaining electrolytes, impairing muscle contraction and fluid regulation. Sports drinks or electrolyte supplements are important for sessions exceeding about 60–90 minutes, or in hot environments with high sweat rates. For shorter sessions, water is generally adequate.
Question 5 Short Answer
Why does the timing of carbohydrate and protein intake around workouts matter, rather than just total daily intake?
Think about your answer, then reveal below.
Model answer: Muscles are most receptive to glycogen replenishment and protein synthesis in the window immediately after training. Pre-workout carbohydrates top off glycogen so the working muscles have fuel during exercise. Post-workout carbohydrates rapidly replenish depleted glycogen and spike insulin, which transports amino acids into muscle cells. Post-workout protein provides amino acids while the muscle synthesis machinery is upregulated. If these nutrients arrive hours later, the anabolic window is partially missed — glycogen replenishment is slower and the stimulus for muscle repair is weaker.
The body's enzymes and receptors for nutrient uptake are upregulated in the hours following exercise. Nutrient timing takes advantage of this sensitivity. This is why professional and competitive athletes treat pre- and post-workout meals as structured, timed events rather than just hitting daily macro targets.