Where a strength coach's scope ends and a dietitian's begins, how the DRI system actually works, protein and carbohydrate targets in g/kg, and the hydration and electrolyte numbers you're expected to know cold.
The ground this chapter covers
Every certified strength and conditioning professional works alongside nutrition questions constantly — an athlete asks what to eat before a session, or how much protein to chase after one — and the exam wants you to know exactly how far you're allowed to go before you have to hand the conversation to someone else.
| Role | Typical credential | What they're cleared to do | Where the line sits |
|---|---|---|---|
| Strength and conditioning professional | CSCS or equivalent; not a licensed nutrition provider | General, evidence-based nutrition education — hydration reminders, describing what a balanced plate looks like, pointing to public health guidelines | Cannot design an individualized eating plan or manage a medical condition through diet |
| Sports dietitian | Registered dietitian (RD/RDN), often holding the CSSD specialist credential in sports dietetics | Individualized meal planning, medical nutrition therapy, body composition and energy availability assessment, supplement evaluation | The professional you refer to for anything condition-specific or person-specific |
| Team physician | MD/DO | Diagnoses and manages medical conditions, including nutrition-related ones (disordered eating, iron-deficiency anemia, GI disease) | Owns the medical picture the dietitian's plan has to work around |
| Athletic trainer | ATC | Recognizes red flags (rapid weight change, fueling around injury/return-to-play) and routes the athlete onward | Not a substitute for dietetic counseling, even informally |
The test you apply to yourself
Ask whether the advice is general ("athletes usually benefit from eating protein at each meal") or individualized ("here is exactly what you should eat given your labs, your GI symptoms, and your weight-loss goal"). The first is education anyone on staff can give. The second is nutrition counseling, and once food is being used to treat or manage a diagnosed condition, that's medical nutrition therapy — both belong to the dietitian. Licensure rules on exactly where that line falls vary by state, but the safe default on the exam is: individualize it, and it's outside your scope.
Population-level guidance gets translated into two everyday tools: a visual plate model for the general public, and an athlete-adjusted version that shifts the proportions toward more fuel and more protein.
| General public plate | Athlete-oriented plate | |
|---|---|---|
| Vegetables/fruit | About half the plate | Roughly a third — still a priority, but it yields room to fuel |
| Grains/starches | About a quarter | Scaled up toward a third or more on heavy training days |
| Protein | About a quarter | A consistent quarter-plate every meal, not just at dinner |
| Fluid | A glass of water or low-fat dairy | Sized and timed around training — before, during, and after, not just with meals |
| Governing idea | Prevent chronic disease across a sedentary-leaning population | Support the extra energy, protein, and fluid turnover training creates |
The Dietary Reference Intakes (DRIs) are the reference-value framework nutrition science runs on. Four values live under that umbrella, and each answers a completely different question — which is exactly why the exam likes to test them against each other.
| Value | What it answers | How it's used |
|---|---|---|
| EAR — Estimated Average Requirement | The intake that meets the needs of half of healthy people in a group | The statistical building block the RDA is calculated from; used to judge whether a population's intake is adequate |
| RDA — Recommended Dietary Allowance | The intake that meets the needs of nearly all (97–98%) healthy people in a group | The number you actually hand an individual as a target |
| AI — Adequate Intake | A best-estimate target used when there isn't enough evidence to calculate an EAR/RDA | Based on observed intakes in apparently healthy people (e.g., used for several minerals and for total fiber) |
| UL — Tolerable Upper Intake Level | The highest daily intake unlikely to cause harm | A ceiling, not a goal — exceeding it doesn't add benefit, it adds risk |
Keeping EAR and RDA straight
EAR is built around the average person — half the group needs more than that number. The RDA deliberately overshoots the EAR (roughly EAR plus two standard deviations) so that it covers nearly everyone, not just the average case. That's also why an individual's intake should be compared against the RDA, while a population's average intake gets compared against the EAR.
Protein's defining job is structural and functional, not primarily fuel: it builds and repairs contractile tissue, enzymes, hormones, and antibodies. It can be burned for energy, but the body treats that as a last resort, not its intended role.
| Class | Amino acids | What defines the class |
|---|---|---|
| Essential (indispensable) — 9 | Histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, valine | The body cannot synthesize these at all — diet is the only source |
| Conditionally essential — 6 | Arginine, cysteine, glutamine, glycine, proline, tyrosine | Normally synthesized in adequate amounts, but demand can outstrip supply during illness, injury, or heavy training stress |
| Nonessential (dispensable) — 5 | Alanine, asparagine, aspartic acid, glutamic acid, serine | The body synthesizes these readily from other compounds |
Of the essential amino acids, leucine gets singled out constantly in sports nutrition — it directly triggers the mTOR pathway that turns on muscle protein synthesis, which is why "leucine threshold" shows up as its own concept in dosing discussions below.
| Factor | What it measures | Key term |
|---|---|---|
| Amino acid completeness | Whether a protein supplies all nine essential amino acids in amounts proportional to human need | A complete protein (most animal sources, soy) vs. an incomplete one (most single plant sources) |
| Digestibility | How much of the ingested protein is actually absorbed and available to the body | Animal proteins generally digest more completely than many plant proteins |
| PDCAAS | Protein Digestibility-Corrected Amino Acid Score — combines amino acid profile with digestibility into one 0–1.0 scale | The older standard scoring method |
| DIAAS | Digestible Indispensable Amino Acid Score — the newer method, measuring digestibility at the point where amino acids actually get absorbed (the small intestine) rather than across the whole gut | Considered a more accurate successor to PDCAAS |
| Population | Typical target |
|---|---|
| AMDR for protein (general population) | 10–35% of total daily energy |
| RDA (sedentary adult, minimum to avoid deficiency) | ~0.8 g/kg/day |
| Endurance athlete | ~1.2–1.4 g/kg/day |
| Strength/power athlete | ~1.6–2.0 g/kg/day |
| Athlete in an energy deficit (preserving lean mass while cutting) | Toward the higher end, sometimes above 2.0 g/kg/day |
Applied — why spacing beats stacking
Eating the same total daily protein in three evenly spaced 30 g doses stimulates more cumulative muscle protein synthesis than eating it in one enormous dinner dose — the synthesis machinery responds to a dose, plateaus, and needs time to become responsive again before the next one does anything. This is the practical argument behind "protein at every meal" rather than "protein at the biggest meal."
Carbohydrate is the body's preferred fuel for moderate-to-high intensity work because it can be broken down anaerobically when oxygen delivery can't keep pace, and it yields ATP faster per unit time than fat can.
| Category | Subtype | Examples |
|---|---|---|
| Simple | Monosaccharide | Glucose, fructose, galactose |
| Disaccharide | Sucrose (glucose+fructose), lactose (glucose+galactose), maltose (glucose+glucose) | |
| Both are quickly digested — the "quick energy" carbohydrates | ||
| Complex | Oligosaccharide / polysaccharide (digestible) | Starch, glycogen |
| Polysaccharide (largely indigestible) | Fiber (cellulose and related structural carbohydrates) | |
Glycemic index (GI) ranks how quickly a food's carbohydrate raises blood glucose relative to a reference food, gram for gram. It says nothing about serving size — that's what glycemic load adds.
| Category | GI range | Example foods |
|---|---|---|
| Low | ≤55 | Lentils, chickpeas, most beans, oats, many whole fruits |
| Medium | 56–69 | Brown rice, whole wheat bread, sweet potato |
| High | ≥70 | White bread, white rice, russet potato, most sports drinks (by design) |
Equation 10.1 — Glycemic load
GL = (GI × grams of carbohydrate per serving) ÷ 100
Categories: low GL ≤10, medium 11–19, high ≥20. A food can carry a high GI but a modest GL if the serving itself is low in carbohydrate — watermelon is the textbook example, with a high GI but a low GL per typical serving.
Fat is the body's most energy-dense fuel and its dominant store, but it can only be metabolized aerobically — which is exactly why it can't take over when intensity climbs and oxygen delivery becomes the bottleneck.
| Term | Structure | General health association |
|---|---|---|
| Saturated fat | No double bonds between carbons; typically solid at room temperature | Recommended in limited amounts; associated with raised LDL when it replaces unsaturated fat |
| Monounsaturated fat | One double bond | Associated with favorable lipid profiles (olive oil, avocado, nuts) |
| Polyunsaturated fat | Two or more double bonds | Includes the essential fatty acids |
| Trans fat | Unsaturated fat chemically altered (hydrogenated) into a straighter, saturated-like shape | No known safe level of intake — minimized as far as possible |
| Essential fatty acids | Omega-3 (alpha-linolenic acid) and omega-6 (linoleic acid) | Cannot be synthesized by the body — diet is the only source |
| Marker | Desirable | Borderline/elevated | High |
|---|---|---|---|
| Total cholesterol | <200 mg/dL | 200–239 mg/dL | ≥240 mg/dL |
| LDL ("bad") | <100 mg/dL | 100–159 mg/dL | ≥160 mg/dL |
| HDL ("good") | ≥60 mg/dL (protective) | 40–59 mg/dL | <40 mg/dL is low-risk-unfavorable |
| Triglycerides | <150 mg/dL | 150–199 mg/dL | ≥200 mg/dL |
A detail worth not missing
Unlike total cholesterol and LDL, higher HDL is the desirable direction — it's the cholesterol transport particle credited with carrying cholesterol away from tissue and back to the liver. And the panel has to be drawn fasted, because a recent meal transiently spikes triglycerides and can shift the calculated LDL value.
Vitamins and minerals don't supply energy themselves, but several of them are the coenzymes and cofactors that let energy metabolism run at all — which is why a real deficiency shows up as fatigue and impaired performance long before it shows up as anything more dramatic.
| Vitamin | Primary role relevant to performance |
|---|---|
| B-complex (thiamin, riboflavin, niacin, B6, B12, folate) | Coenzymes in carbohydrate, fat, and protein energy metabolism; B12 and folate also support red blood cell production |
| Vitamin D | Calcium absorption and bone mineralization, immune function, and a direct role in skeletal muscle function |
| Vitamin C | Antioxidant; collagen synthesis (connective tissue, tendon); enhances nonheme iron absorption |
| Vitamin E | Fat-soluble antioxidant, protects cell membranes from oxidative damage |
| Vitamin K | Blood clotting factors; also involved in bone protein formation |
| Mineral | Primary role |
|---|---|
| Calcium | Bone mineral density, muscle contraction (crossbridge cycling), nerve signal transmission |
| Iron | Core of hemoglobin and myoglobin — oxygen transport and storage; low iron directly caps aerobic capacity |
| Sodium | Primary extracellular electrolyte; fluid balance, nerve conduction, blood volume |
| Potassium | Primary intracellular electrolyte; fluid balance, nerve conduction, muscle contraction |
| Magnesium | Cofactor in hundreds of enzymatic reactions including ATP utilization; muscle and bone function |
| Zinc | Immune function, protein synthesis, tissue repair/wound healing |
Nutrients of public health concern
Population survey data consistently shows underconsumption of fiber, vitamin D, calcium, and potassium — these are flagged as nutrients of public health concern across the general population. Iron gets added to that list specifically for adolescent and adult female athletes, who lose iron through menstruation on top of the sport-related losses (GI blood loss, foot-strike hemolysis, sweat) that any endurance athlete faces.
Water is the single nutrient an athlete can least afford to get wrong in the short term — a large fluid deficit degrades performance and can become dangerous within a single session, long before any other nutritional shortfall would.
Sweat isn't pure water — it carries sodium and, to a lesser degree, potassium out with it. Sport drink formulas are built around replacing sodium primarily, since it's the electrolyte lost in the largest quantity and the one most tied to fluid retention.
The thresholds themselves
Normal serum sodium sits around 135–145 mmol/L. Below 130 mmol/L, symptoms (nausea, headache, confusion) typically appear. Below 125 mmol/L is considered a serious medical emergency. Below 120 mmol/L carries a real risk of seizure, coma, or death from cerebral edema. The exam frequently asks you to recognize that an athlete who has been drinking aggressively throughout a long event and becomes confused near the finish is more likely hyponatremic than dehydrated.
| Marker | Euhydrated | Signals dehydration |
|---|---|---|
| Urine color | Pale yellow, like lemonade | Progressively darker, toward apple-juice color |
| Urine specific gravity (USG) | ≤1.020 | >1.020, and especially >1.030 |
| Body mass change | Same-day swings <1% | ≥2% loss from a training session |
These two terms get used interchangeably by athletes and coaches, but they describe completely different mechanisms — and mixing them up matters, because one of them can be life-threatening within minutes.
| Food allergy | Food intolerance/sensitivity | |
|---|---|---|
| Mechanism | Immune-mediated — typically an IgE antibody response | Non-immune — usually a digestive or metabolic issue (e.g., missing an enzyme) |
| Onset | Minutes to about two hours | Can take hours, sometimes longer, to appear |
| Severity | Can escalate to anaphylaxis — a medical emergency | Uncomfortable (bloating, GI distress) but not immediately life-threatening |
| Dose dependence | Even trace amounts can trigger a reaction | Often dose-dependent — a small amount may be tolerated |
| Common examples | Peanut, tree nut, shellfish, milk, egg, wheat, soy | Lactose intolerance, non-celiac gluten sensitivity |
| Management | Strict avoidance; carrying emergency epinephrine | Avoidance or dose reduction; less strict, no emergency medication required |
An athlete wants a personalized meal plan built around a diagnosed iron-deficiency anemia. Who is responsible for building that plan?
C. Using food to manage a diagnosed medical condition is medical nutrition therapy — squarely the registered dietitian's scope, not general nutrition education.
Which DRI value represents the intake that meets the needs of only half of a healthy population?
D — EAR. The RDA is deliberately set higher than the EAR so it covers nearly the entire healthy population, not just the statistical average person.
A strength athlete weighing 90 kg is targeting 1.8 g/kg/day of protein. Approximately how many grams of protein is that per day?
C. 90 kg × 1.8 g/kg = 162 g/day.
Which measure evaluates protein quality by accounting for both amino acid profile and digestibility measured specifically at the small intestine?
B — DIAAS. PDCAAS also corrects for digestibility, but measures it across the whole digestive tract rather than at the point of amino acid absorption, which is considered less accurate.
A food has a glycemic index of 80 and a serving contains 15 g of carbohydrate. What is its glycemic load, and how is it classified?
B. GL = (80 × 15) ÷ 100 = 12, which falls in the medium range (11–19) despite the food's high GI — the small serving size limits the total glucose load.
Which lipid panel finding is generally considered protective rather than a risk marker?
C. HDL is the exception — unlike LDL, total cholesterol, and triglycerides, a higher HDL value is the desirable direction.
Late in a marathon, an athlete who has been drinking large volumes of plain water becomes confused and nauseated. What should you suspect first?
C. Aggressive plain-water intake without adequate sodium replacement is the classic setup for exercise-associated hyponatremia — a dilution problem that mimics dehydration symptoms.
An athlete loses 2.0 kg of body mass over a training session. Using the standard rehydration guideline, roughly how much fluid should they drink afterward to fully rehydrate?
C. The guideline is about 1.5 L of fluid per kg of body mass lost, to account for continued urine output during rehydration: 2.0 kg × 1.5 L/kg = 3.0 L.
Which best distinguishes a food allergy from a food intolerance?
B. A true allergy involves the immune system (typically IgE) and can escalate to anaphylaxis; an intolerance is a digestive or metabolic issue that's uncomfortable but not immediately dangerous.
Which pair of foods correctly matches high vs. low glycemic index categories?
B. White rice sits in the high GI range (≥70); lentils sit in the low range (≤55) thanks to their fiber and protein content slowing digestion.
This chapter is original study material covering topics also addressed in Essentials of Strength Training and Conditioning, 5th edition (NSCA/Human Kinetics). It is an independent work, not a reproduction or paraphrase of that text. This guide is not affiliated with, endorsed by, or sponsored by the National Strength and Conditioning Association (NSCA). CSCS® and Certified Strength and Conditioning Specialist® are registered trademarks of the NSCA.