CSCS Nutrition & Performance Enhancement 2 — Questions and Answers

Question 1: What is the recommended daily protein intake for strength-trained athletes to maximize muscle protein synthesis per NSCA guidelines?

0.4-0.6 g/kg/day
0.8 g/kg/day (standard RDA)
1.4-1.7 g/kg/day (Correct answer)
3.0-4.0 g/kg/day

Correct answer: 1.4-1.7 g/kg/day

NSCA recommends 1.4-1.7 g/kg/day for strength-trained athletes to support muscle protein synthesis, recovery, and lean mass maintenance. The standard RDA of 0.8 g/kg/day is insufficient for athletes under heavy training loads.

Protein requirements increase with resistance training due to elevated muscle protein turnover. Current evidence suggests 1.6-2.2 g/kg/day maximizes muscle protein synthesis in resistance-trained athletes; NSCA Essentials uses 1.4-1.7 g/kg/day as the primary recommendation. Higher intakes above 2.2 g/kg provide no additional MPS benefit and the excess is oxidized for energy. Protein distribution matters: approximately 0.4 g/kg per meal every 3-4 hours, with a pre-sleep casein dose of approximately 40 grams, maximizes 24-hour muscle protein synthesis. Total daily calories, energy availability, and leucine content per meal are also critical determinants of net muscle protein balance.

Question 2: Which macronutrient is the most critical fuel source for high-intensity exercise above 70% of VO2max?

Fat (free fatty acids from adipose tissue)
Carbohydrate (muscle glycogen and blood glucose) (Correct answer)
Protein (amino acid oxidation)
Creatine phosphate alone

Correct answer: Carbohydrate (muscle glycogen and blood glucose)

Carbohydrate (muscle glycogen and blood glucose) is the predominant fuel above approximately 70% VO2max because fat oxidation cannot sustain ATP production at the required rate at high exercise intensities.

Exercise intensity determines substrate utilization. At low intensity below 50% VO2max, fat (free fatty acids from adipose and intramuscular triglycerides) dominates. The crossover point (approximately 50-65% VO2max) is where carbohydrate becomes the predominant fuel. Above 70% VO2max, muscle glycogen is the primary fuel because high ATP demand exceeds fat oxidation capacity. Carbohydrate oxidation can produce approximately 100 kcal per minute versus fat's maximum of approximately 30-50 kcal per minute. Glycogen depletion is a primary cause of fatigue in endurance events. CSCS practitioners must ensure athletes consume adequate carbohydrates to support high-intensity training demands and optimize glycogen stores before competition.

Question 3: For exercise sessions lasting 60-90 minutes at moderate-to-high intensity, what is the NSCA-recommended intra-workout carbohydrate intake?

No carbohydrates needed for sessions under 90 minutes
15-20 g of carbohydrate every 30 minutes
30-60 g of carbohydrate per hour of exercise (Correct answer)
100 g of carbohydrate taken as a bolus at the start of exercise

Correct answer: 30-60 g of carbohydrate per hour of exercise

NSCA and ACSM recommend 30-60 g of carbohydrate per hour for sessions lasting 60-90 or more minutes at moderate-to-high intensity to maintain blood glucose, spare glycogen, and delay fatigue.

Intra-workout carbohydrate guidelines from NSCA, ACSM, and IOC: under 60 minutes, carbohydrate is not required; 1-2.5 hours requires 30-60 g per hour; over 2.5 hours allows up to 90 g per hour using multiple transportable carbohydrates. A 2:1 glucose-to-fructose ratio maximizes intestinal absorption by using separate transport proteins (SGLT1 for glucose, GLUT5 for fructose). Common sources include sports drinks (6-8% carbohydrate concentration), energy gels (25 g per serving), or whole food sources such as bananas. Carbohydrate mouth rinsing (without swallowing) also shows performance benefits in short high-intensity events via central nervous system activation pathways.

Question 4: Which ergogenic aid has the strongest evidence base for improving high-intensity short-duration exercise performance per NSCA guidelines?

Branched-chain amino acids (BCAAs)
Creatine monohydrate (Correct answer)
Glutamine supplementation
HMB (beta-hydroxy beta-methylbutyrate)

Correct answer: Creatine monohydrate

Creatine monohydrate has the most robust evidence base for enhancing high-intensity, short-duration performance by increasing intramuscular PCr stores, enabling greater work in 6-30 second activities and supporting greater training volume.

Creatine monohydrate at 3-5 g per day maintenance (or loading at 20 g per day for 5-7 days) increases intramuscular PCr stores by 10-30%, enhancing ATP resynthesis in the phosphagen system. This supports more repetitions at a given load, greater total training volume, faster recovery between sets, and potentially enhanced muscle protein synthesis. Meta-analyses show 5-15% improvements in strength, power, and sprint performance. Creatine is safe, legal, and inexpensive. The NSCA classifies it as a Tier 1 ergogenic aid with strong evidence. Glutamine and HMB have inconsistent evidence in healthy athletes; BCAAs primarily benefit individuals in energy-restricted states or low protein intake conditions.

Question 5: Post-exercise carbohydrate consumption is most critical within which time window to maximize glycogen resynthesis rates?

6-8 hours post-exercise
4-6 hours post-exercise
Within 30-45 minutes post-exercise (Correct answer)
24-48 hours post-exercise

Correct answer: Within 30-45 minutes post-exercise

Glycogen synthase activity is highest immediately post-exercise. Consuming 1.0-1.5 g/kg of high-glycemic carbohydrates within 30-45 minutes maximizes glycogen resynthesis rate and supports recovery for subsequent training sessions.

Post-exercise glycogen resynthesis follows two phases: a rapid insulin-independent phase (first 0-2 hours, highly enzyme-dependent) and a slower insulin-dependent phase (2-8 hours). The recommended protocol for athletes with less than 8 hours between sessions: 1.0-1.5 g/kg high-glycemic carbohydrates immediately post-exercise, then every 2 hours for 4-6 hours. Adding protein (0.3-0.4 g/kg) to post-exercise carbohydrates improves insulin response and net muscle protein synthesis without impairing glycogen resynthesis. When over 24 hours separates training sessions, total daily carbohydrate intake drives glycogen restoration more than acute timing specificity.

Question 6: Exercise-associated hyponatremia in endurance athletes is most commonly caused by which mechanism?

Excessive sodium loss through sweat without electrolyte replacement
Overhydration with plain water, diluting serum sodium below 135 mEq/L (Correct answer)
Insufficient carbohydrate intake causing metabolic disruption
Severe dehydration from insufficient fluid intake during exercise

Correct answer: Overhydration with plain water, diluting serum sodium below 135 mEq/L

Exercise-associated hyponatremia results primarily from overhydration with hypotonic fluids (plain water), diluting serum sodium. Sodium loss through sweat plays a secondary role; the primary cause is excessive fluid intake beyond actual sweat losses.

Exercise-associated hyponatremia (serum Na+ below 135 mEq/L) is most prevalent in prolonged endurance events and is caused by: (1) drinking more fluid than lost through sweating (positive fluid balance); (2) inadequate sodium replacement. Symptoms include nausea, headache, confusion, cerebral edema, and seizures in severe cases. Prevention includes drinking to thirst rather than on a schedule, using electrolyte-containing sports drinks in prolonged events, and avoiding pre-event weight gain from excessive fluid loading. CSCS practitioners educate athletes to drink approximately 400-600 mL 2-3 hours pre-exercise and replace approximately 80% of sweat losses rather than 100% or more to maintain safe euhydration.

CSCS Nutrition & Performance Enhancement 2

What is the recommended daily protein intake for strength-trained athletes to maximize muscle protein synthesis per NSCA guidelines?