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 1.2 - 1.7g protein.kgBW.day. Protein is a vitally important nutrient to all athletes. Current ACSM (2009) recommendations for protein requirements are set at: meeting energy requirements / excess hypoenergetic not acutely unwell older age younger athlete emphasis on hypertrophy less emphasis on hypertrophy illness / trauma

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 www.gssi.web 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.

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% VO 2 max However, CHO requirements • vary widely between athletes Brooks (1985) and many can perform at a very high level, even in low CHO conditions.

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% VO 2 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 • only 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.

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