Cutting through controversies in Sports Nutrition Rick Miller, - - PowerPoint PPT Presentation

Cutting through controversies in Sports Nutrition

Rick Miller, MSc., RD. @Rick_M_RDiet

Today’s Content

• Current evidence for protein

requirements and nutrient timing.

• Rethinking carbohydrates for

sports people, how much, when and to carb-load or not?

• The role of dietary fats in

sports performance

• Simplifying Ergogenic Aids &

Dietary Supplements

Protein Requirements

Protein is a vitally important nutrient to all athletes. Current recommendations for protein requirements are set at: 1.2 - 1.7g protein.kgBW.day.

ACSM (2009)

hypoenergetic

• lder age

emphasis on hypertrophy illness / trauma meeting energy requirements / excess not acutely unwell younger athlete less emphasis on hypertrophy

What are the benefits?

• Aids the recovery process from

training

• Supports recovery from injury /

surgery

• May support training adaptations

(particularly leucine-rich foods)

• Reduces the risk of infection.
• May increase adherence to a hypo-

energetic diet.

What are the concerns?

• The ‘more is better’ paradigm.
• What are the long term effects?
• Who are our ‘at risk’ groups?
• Supplementation is potentially

expensive and ‘may’ detract from eating a varied diet.

• Supplementation is likely to aid

the few (highly trained) rather than plenty (novice)

Protein: Nutrient timing

• There is an upper limit to stimulation of protein synthesis from

a meal containing protein and a refractory period thereafter. This is reached between ~0.25g protein/kg bodyweight per meal.

• Provision of protein in the immediate period after exercise if

likely to speed up the recovery process, untrained individuals show a prolonged anabolic response but a smaller peak in PS. www.gssi.web

Protein Summary

• Total protein intake reflect the athlete’s

training goals as well as the demands of their sport.

• Protein should be provided in bolus amounts

throughout the day to exceed the threshold for leucine. Excess is not used for skeletal tissue regeneration.

• Regular anthropometric and training

assessment should guide your dietetic treatment.

• Protein supplementation to meet

requirements is convenient and may be warranted for certain athletes but can be met with food in most cases.

Rethinking Carbohydrates

• Previous thinking would have

approached the requirements of carbohydrate by looking at the needs of a ‘sport’.

• Carbohydrate is the

predominant substrate for exercise performed at >60-70% VO2 max

• However, CHO requirements

vary widely between athletes and many can perform at a very high level, even in low CHO conditions. Brooks (1985)

What effect do we want?

Bartlett et al. (2014)

Bartlett et al. (2014)

To Load or Not to Load?

• Carbohydrate loading can

enhance the performance of athletes competing in events lasting >90 minutes by ~20% and reduce time to fatigue by 2-3% (Hawley et al. 1997).

• The traditional CHO load model is

to reduce training volume by 50% in the last week before race (tapering) and maintain/increase CHO over 3 days.

• Any form of CHO can be used

and a mixture should be encouraged to ensure CHO requirements are met.

Carbohydrate Summary

• Carbohydrate needs for most

athletes should incrementally increase with duration of exercise and time spent at >60% VO2 max

• Provision or restriction of

carbohydrates may also be dependent on the effect the athlete is trying to achieve “Train low does not mean “Train with no CHO”

• Carbohydrate loading can be

achieved in as little as 24 hours, not all athletes will see benefit and it should be practiced.

Fats in Sports Performance

Dietary fats have a number of roles to perform to the athlete. Hedonistic qualities and improved satiety.

• Long chain PUFAs suppress some aspects of the

inflammatory response and also aid:

• Tissue recovery from exercise, protein synthetic

response from a meal and upper respiratory tract function (EIB).

• The long term effects of a diet <15% total energy

from fat is associated with a worsened immune and hormonal profile.

Dietary Fats as a Fuel

• Dietary fat has also been

researched as a potential fuel source for exercise.

• Those papers that have seen a

benefit to this protocol note that the athlete must enter and remain in nutritional ketosis (Volek et al. 2014)

• No evidence that this approach

improves intermittent sports or those with a high glycogen dependence (tendency to worsen).

Dietary Fat Summary

• Athletes should not be encouraged to

adopt very low fat diets due to no reported benefit on performance and potential health risks.

• Concentrating on MUFA/PUFAs is

likely to be sufficient without further investigation of the athlete’s biochemistry.

• The use of a high fat/ketogenic diet is

at this stage limited to a few athletes, difficulty maintaining high intensity exercise for prolonged periods and adherence make it impractical for many.

Simplifying Ergogenic Aids & Supplements

Use of dietary supplements and ergogenic aids is widespread in the population and even higher in amongst sportspeople. “If you could take a pill that would guarantee you the olympic gold medal but would kill you within a year, would you take it?” (Mirkin, 1987) Reports suggest that up to 80% of athletes use a form of dietary supplement for the following:

• To aid recovery from training
• For health
• To improve performance
• To prevent or treat an illness
• To compensate for a poor diet

What works?

Far less than is on that shelf…

• Source. Maughan (2011)

Consequences?

• Drug testing at Olympic Level is

controlled by the World Anti-Doping Agency (WADA). Code here

• The risks of positive doping test (Banned

Substances) are real.

• WADA applies a strict liability principle

and does not distinguish inadvertent and deliberate doping practices. The liability lies with the athlete.

• Products registered with Informed Sport

are the most likely to be safe. These have been batch tested by HFL laboratories (Cambridge) to ensure no banned substances.

Ergogenic Aids & Supplements Summary

• There is evidence for the use of

certain ergogenic aids but be aware of the issues of contamination and safety.

• Dietary supplementation should
• nly be advised where it is clear

that obtaining nutrients through diet alone is likely to be difficult/impossible.

• Be mindful of the nocebo effect, is

removal likely to harm performance?

American College of Sports Medicine, American Dietetic Association, Dietitians of Canada: Joint Position Statement (2009) Nutrition and Athletic Performance. Journal of the American Dietetic Association, 109(3), p.509-527 Bartlett, J.D., Hawley, J.A. & Morton, J.P. (2014) Carbohydrate Availability and Exercise Training: Too Much of a Good Thing? European Journal of Sports Science Brooks, G.A. & Mercier, J. (1985) Balance of carbohydrate and lipid utilization during exercise: the “crossover”

• concept. Journal of Applied Physiology, 76(6), p.2253-2261

Burke, L.M. & Maughan, R.J. (2014) The Governor has a sweet tooth - Mouth sensing of nutrients to enhance sports performance. European Journal of Sports Science, 15(1), p.29-40 Maughan, R.J. (2011) Dietary Supplements for Athletes, Emerging Trends and Recurring Themes. Journal of Sport Sciences Moore, D.R., Churchward-Venne, T.A., Witard, O., Breen, L., Burn, N.A., Tipton, K.D. & Phillips, S.M. (2015) Protein ingestion to stimulate myofibrillar protein synthesis requires greater relative protein intakes in healthy older versus younger men. The Journals of Gerontology Series A: Biological Sciences and Medical Sciences, 70(1), p57-62 Meeusen, R. (2014) Exercise, Nutrition and the Brain. Sports Medicine, 44(Supp1), S47-S56 Volek, J.S., Noakes, T. & Phinney, S.D. (2014) Rethinking fat as a fuel for endurance exercise. European Journal of Sports Sciences. WHO Technical Report Series 935. Protein and amino acid requirements in human nutrition: report of a joint FAO/WHO/ UNU expert consultation. WHO; 2011.

Any Questions?