Sports Nutrition - Week 11

What is the main learning outcome of the sports nutrition lecture?

Develop a basic understanding of unique nutritional needs and dietary issues relevant to athletes.

Why should athletes care about nutrition?

It supports body composition, health and wellbeing, immune function (illness can mean missed training), mental resilience, performance and training adaptation; in endurance events, food before and during competition can strongly affect performance.

What is physiological adaptation to training?

How the body responds to a training stimulus.

How can carbohydrate availability influence physiological adaptation?

Changing muscle carbohydrate availability can influence which enzymes are activated and improve the muscle's capacity to use carbohydrate during exercise.

What performance factors can nutrition influence?

Power, speed, endurance, perceived exertion and recovery time.

Is there one ideal athlete diet?

No. Sports differ in physiology, body composition, training loads and nutrition-support needs; individuals within the same sport can also differ.

Can athletes in the same team need different diets?

Yes. Individual athletes can have different requirements and meet goals in different ways.

What healthy-eating foundations apply to athletes?

Meet energy needs; eat a variety of foods across and within all food groups; choose mostly minimally processed, quality foods; keep discretionary foods to a small proportion.

Are there separate Nutrient Reference Values for athletes in the lecture?

No separate athlete NRVs are provided; some athletes may need to adjust how they eat.

What does a personalised sports nutrition approach involve?

Matching dietary advice to each athlete's needs, goals and training situation.

Why should athletes adjust food intake across a training cycle?

Their workload and adaptation goals change across the week and training cycle.

How should athletes adjust energy and carbohydrate intake to workload?

Adjust intake day to day: generally eat more, especially carbohydrate, as training load rises and reduce intake somewhat when workload falls.

How can a meal be adjusted for a light training day?

Keep the meat/protein portion similar; reduce but do not remove potato, pasta, noodles or rice; add vegetables or salad.

How can athletes adjust intake on lighter training days without changing meals?

They can reduce or remove some snacks compared with a heavy training day.

Why is carbohydrate important during exercise?

It is an important fuel, especially at high intensities or when oxygen supply is low.

Why is carbohydrate especially important at high exercise intensities?

The body can use it rapidly to support high work output.

Can the body use fat as fuel at high intensities as easily as carbohydrate?

No. The capacity to use fat as fuel is limited at higher intensities.

What is carbohydrate depletion strongly linked to?

Fatigue during prolonged, sustained or intermittent high-intensity exercise.

Why must athletes consume sufficient carbohydrate?

The body's capacity to store carbohydrate is limited, so intake needs to match exercise demands.

Does every athlete need a high-carbohydrate diet?

No. Carbohydrate needs depend on the type, duration and intensity of exercise.

What fuels can contribute during lower-intensity exercise?

A mix of carbohydrate, fat and protein can be used; the lecture gives jogging as an example of lower-intensity exercise.

What happens when carbohydrate availability is too low during exercise?

High-intensity output falls if muscle glycogen and blood glucose are insufficient; during longer, lower-intensity work, running low on carbohydrate also reduces output and session quality.

What carbohydrate intake is suggested for low-intensity or skill-based activity?

Approximately 3–5 g/kg/day.

What carbohydrate intake is suggested for about one hour of moderate exercise per day?

Approximately 5–7 g/kg/day.

What carbohydrate intake is suggested for 1–3 hours of moderate-high intensity exercise per day?

Approximately 6–10 g/kg/day.

What carbohydrate intake is suggested for more than 4–5 hours of moderate-high intensity exercise per day?

Approximately 8–12 g/kg/day.

What determines an athlete's daily carbohydrate requirement?

Activity level, exercise duration, intensity and training goals. These are broad guidelines; needs vary between athletes and change with workload.

What was the design of the Hansen et al. train-low study?

Untrained subjects consumed a high-carbohydrate diet (8 g/kg) and completed a 10-week program; researchers compared a low-glycogen leg with a high-glycogen leg.

How did the train-low leg train in the Hansen study?

Two sessions per day every second day; the second session was performed with low muscle glycogen.

How did the train-high leg train in the Hansen study?

One session per day, with all sessions performed under high-glycogen conditions.

What adaptations were reported in the train-low leg?

Improved muscle glycogen content, increased oxidative enzymes and improved time to fatigue.

Which signalling proteins become more active with low carbohydrate availability?

PGC-1α, AMPK, p38 MAPK and p53; manipulating carbohydrate availability can affect transcriptional activity and protein expression/signalling.

What is the 'train low, compete high' approach?

Do selected training sessions with low carbohydrate availability, but compete with high carbohydrate availability.

Should endurance athletes do every session with low carbohydrate availability?

No. Select sessions strategically according to their goals and demands.

How can athletes create low carbohydrate availability for selected sessions?

Options include a low-CHO diet or manipulating timing: no recovery food between twice-daily sessions, a long session (e.g. 4-hour ride) without CHO, or training after an overnight fast. A low-CHO diet is not essential.

Which athletes are low-carbohydrate-availability strategies mainly intended for?

Endurance athletes, when the strategy suits a specific session goal.

In the swimmer periodisation example, which sessions require high carbohydrate availability?

Quality, high-intensity sessions where the athlete must produce strong outputs.

How did the swimmer example create low carbohydrate availability before a selected session?

A low-carbohydrate meal on Wednesday night followed by no breakfast before Thursday morning training.

Does carbohydrate periodisation mean eating little carbohydrate every day?

No. Overall intake can remain reasonably high while being adjusted day to day and session to session.

What is the adult male 19–50 years protein RDI shown in the lecture?

The Recommended Dietary Intake (RDI) for a male adult aged 19–50 is 0.84 g/kg/day.

What daily protein range is shown for athletes in the lecture?

Approximately 1.5–2 g/kg/day.

Do athletes generally need more protein than sedentary people?

Yes, but usually not as much as many athletes believe.

Which athletes might require less protein than athletes in a new training phase?

Highly trained athletes.

Why may many Australians already consume enough protein for athletic requirements?

The lecture notes that a typical Australian diet provides about 1.5 g/kg/day.

When can meeting daily protein requirements become difficult?

When total energy intake is restricted.

What did post-exercise protein dose-response research find?

Studies compared different protein amounts after exercise; about 20 g soon after training best stimulated muscle protein synthesis, with no significant extra effect from increasing to 40 g.

What were the three protein-ingestion patterns compared in the AIS study?

Bolus: 2 × 40 g every 6 h; intermediate: 4 × 20 g every 3 h; pulse: 8 × 10 g every 1.5 h.

Which protein-ingestion pattern produced the best outcomes in the AIS study?

The intermediate pattern: about 20 g every three hours.

Why might athletes spread protein more evenly across the day?

A typical Australian pattern puts much protein at the evening meal. The lecture says daily protein spread is just as important as total amount and suggests distributing intake more evenly across meals.

What did the 2023 Trommelen research suggest about the anabolic response to protein?

The response during recovery may have no upper limit in magnitude and duration in vivo in humans.

Why should short-term muscle-protein-synthesis studies be interpreted cautiously?

Tracer studies often measure short periods and may not reflect longer-term protein metabolism.

What does longer-term research suggest about protein distribution?

If total daily protein is sufficient, precise distribution may add little or no further benefit; evidence is still developing, so it is premature to say distribution has no benefit. Practically, focus on meeting total daily protein without stressing over timing.

What practical protein advice is given if the next meal is within five hours?

Consume at least 20 g of protein.

What practical protein advice is given if the next meal is more than five hours away?

Consume at least 40 g of protein.

What is the rationale behind a low-carbohydrate, high-fat (LCHF) diet for athletes?

Proposed especially for endurance athletes: the body has large fat stores but limited carbohydrate stores; adapting to greater fat use may spare carbohydrate and delay fatigue.

What ketogenic carbohydrate intake is described in the lecture?

Very low carbohydrate intake of less than 20 g/day.

What defines the non-ketogenic LCHF approach in the lecture?

More than 60% of energy from fat and less than 25% from carbohydrate.

What is fat adaptation?

A period of LCHF eating followed by high-carbohydrate eating.

How can several days of LCHF eating affect metabolism?

After about five days or longer, the body may become more efficient at using fat as fuel.

What potential performance disadvantage can accompany LCHF adaptation?

It may impair carbohydrate metabolism and reduce efficiency of carbohydrate use during high-intensity exercise.

What was the Supernova race-walker study investigating?

High-carbohydrate availability, LCHF and periodised carbohydrate availability during intensified training.

How many athletes took part in the Supernova study and how long was the intervention?

29 world-class race walkers completed a three-week high-volume training program.

What were the three dietary interventions in the Supernova study?

High carbohydrate; LCHF (<50 g carbohydrate/day, 75–80% fat); and periodised intake (train high, train low, sleep low).

What was the main performance conclusion of the Supernova study?

Metabolic benefits were seen across diet groups, but LCHF negated the performance benefit of intensified training: the LCHF group did not improve its 10 km time trial as much as the other groups.

In what situations might LCHF be considered potentially beneficial?

Prolonged submaximal activity without high-intensity demands, events where sufficient carbohydrate is difficult to consume, or some carbohydrate-sensitive individuals.

How does the lecturer suggest estimating dietary fat needs?

Set protein and carbohydrate requirements first, then fit fat into the remaining energy budget.

What is the main nutrition priority during training?

Optimise adaptation and periodise carbohydrate availability.

What is the main nutrition priority during competition?

Optimise performance by ensuring suitable carbohydrate and fluid availability.

What should athletes consider when choosing food before exercise?

Carbohydrate availability, hydration, gastrointestinal comfort and mental confidence.

What determines what an athlete should eat before exercise?

Exercise type and duration, opportunities to eat or drink during it, and individual tolerance and preferences.

Why is a pre-exercise meal useful?

It helps top up liver glycogen stores.

How does the time before exercise affect food choices?

The closer exercise is, the less time there is to digest and absorb food; avoid exercising with food still sitting in the stomach.

What should be considered for nutrition during exercise?

Carbohydrate availability according to workload and opportunity; fluid delivery according to fluid losses and opportunity; and gastrointestinal (GIT) comfort.

What determines whether an athlete needs food and fluid during exercise?

What they ate beforehand and how long the event or session lasts.

What carbohydrate strategy is suggested for exercise lasting about 30–75 minutes?

A carbohydrate mouth rinse may be used; carbohydrate intake may not be needed.

What carbohydrate intake is suggested during exercise lasting 1–3 hours?

Approximately 30–60 g per hour.

What carbohydrate intake is suggested during exercise lasting more than three hours?

Up to about 90 g per hour, using mixed carbohydrate sources such as glucose plus fructose.

Why should athletes train their gut when aiming for high carbohydrate intakes during long events?

To develop tolerance to the high intake and support carbohydrate absorption.

Why does the type of sport affect food choices during exercise?

Some activities make eating easier; cycling provides more opportunity than marathon running.

What is the starting hydration recommendation before exercise?

Start the session hydrated.

How should fluid be consumed during exercise?

Use small, frequent intakes rather than large volumes near the end.

When may drinking to thirst be sufficient?

For short (<1 h), easy sessions in cool conditions (<25°C) with low fluid losses.

When should athletes consider an individual drinking plan?

During long, hard or hot sessions with higher fluid losses; use an individual plan to drink enough to nearly match losses.

How can an athlete estimate individual fluid losses?

Weigh before and after exercise to estimate fluid loss and help plan intake.

What body-mass loss target is suggested for the end of an exercise session?

Aim to finish within 2% of starting body weight.

What sweat-rate range is mentioned in the lecture?

Approximately 300 mL to 2.5 L per hour.

When is water during exercise in the heat generally recommended in the lecture?

For exercise lasting longer than about 30 minutes.

Why should athletes avoid over-drinking during prolonged exercise?

Excessive fluid intake can contribute to hyponatraemia, especially during exercise lasting more than 2 hours; avoid excessive drinking before and during the event.

Which circumstances can increase the risk of over-drinking?

Excessive fluid intake before exercise, low sweat rates with ample opportunities to drink, and smaller athletes, especially women.

When may sodium need to be consumed during exercise?

When sweat sodium losses are large: high sweat rates (>1.2 L/h), salty sweat, or exercise lasting more than about 2 hours. Sodium is generally not needed for shorter sessions.

Why can sports drinks encourage fluid intake?

Their sodium content can stimulate thirst.

What are the four recovery 'R's' after exercise?

Refuel, rehydrate, repair and revitalise.

Which nutrient matches each of the four recovery 'R's'?

Refuel: carbohydrate; rehydrate: fluid; repair: protein; revitalise: vitamins. The lecture also notes that vitamins and minerals help cellular recovery.

Why should nutrients be available soon after exercise?

Recovery can be faster when nutrients are available soon after exercise.

What does carbohydrate do during recovery?

Replaces muscle glycogen used during exercise.

What is the role of protein after exercise?

Supports repair and cellular recovery.

Why can flavoured milk be a useful recovery option, and what might still be needed?

It provides carbohydrate, fluid, protein and vitamins; the slide leaves total energy needs uncertain, and most athletes also need extra water. Other food-and-fluid combinations can work too.

When might aggressive recovery nutrition be needed?

Match recovery to the time and demands: more aggressive strategies may be needed with less than 8 h between sessions, high energy needs or tournaments; when training once daily, the next meal may be sufficient.

What approach to supplements does Australian sport promote?

A food-first approach: meet performance goals through a good mix of real foods wherever possible.

What three qualities should an athlete's supplement use meet?

Supplements should be safe, necessary and effective.