NMDS311 Sports Nutrition

Transcription

1 NMDS311 Sports Nutrition Session 3 Carbohydrate Nutritional Medicine Department

2 Sports Nutrition Session 3 Carbohydrates (CHO) Sources and Types Guidelines for CHO consumption before, during and after exercise Endeavour College of Natural Health 2

3 CHO = Key Fuel CHO is needed to fuel almost every type of activity High muscle glycogen Extends duration Able to train at optimal intensity Low muscle glycogen Early fatigue Reduced training intensity (Bergstrom et al., 1967) Endeavour College of Natural Health 3

4 Daily Guidelines Intensity Situation Carbohydrate Targets Light Low-intensity or skill-based activities 3 5 g/kg BM (~60mins) Moderate Moderate exercise program (90-120mins) 5-7 g/kg BM High Very High Endurance exercise program (i.e. moderate-to-high intensity exercise of 2-3 hr / day) Extreme exercise intensity (i.e. high intensity exercise of >4-5 hr / day) 6-10 g/kg BM 8-12 g/kg BM (AIS Sports Nutrition, 2014) Endeavour College of Natural Health 4

5 CHO Sources CATEGORY DESCRIPTION EXAMPLES USE FOR ATHLETES Nutrient-dense carbohydrate Nutrient-poor carbohydrate High-fat carbohydrate Foods and fluids that are rich sources of other nutrients including protein, vitamins, minerals, fibre and antioxidants in addition to carbohydrate Foods and fluids that contain carbohydrate but minimal or no other nutrients Foods that contain carbohydrate but are high in fat Breads and cereals, grains (e.g. pasta, rice), fruit, starchy vegetables (e.g. potato, corn), legumes and sweetened low-fat dairy products Soft drink, energy drinks, lollies, carbohydrate gels, sports drink and cordial Pastries, cakes, chips (hot and crisps) and chocolate Everyday food that should form the base of an athlete s diet. Helps to meet other nutrient targets Shouldn t be a major part of the everyday diet but may provide a compact carbohydrate source around training Sometimes foods best not consumed around training sessions (AIS Sports Nutrition, 2014) Endeavour College of Natural Health 5

6 CHO Loading Dietary Strategy to super compensate muscle glycogen levels Potentially advantageous for: Endurance events >90mins Tournament or swim meets Long team games involving intermittent work patterns (e.g. AFL, NRL, soccer) Improves time to exhaustion (TTE) by about 20% and performance by about 2-3% Retrieved from: Endeavour College of Natural Health 6

7 CHO Loading Classic Protocol - In the Week leading into the race Day 1 Glycogen depleting exercise bout Day days of low CHO diet (<1-2g/kg BW/day) Day 4 - Glycogen depleting exercise bout Day days of high CHO diet (>10g/kg BW/day) Day 7 Race Day Endeavour College of Natural Health 7

8 CHO loading Challenges of Classic Protocol Poor compliance Reducing CHO intake suddenly can cause the athlete to feel very tired quite quickly It can also increase the risk of injury whilst exercising on low glycogen levels. Endeavour College of Natural Health 8

9 CHO Loading Modern Approach Exercise taper leading into race week. Day before the race: Inactivity most of the day + a high CHO intake (generally 3-4g/kg BW greater than their normal intake) Shown to increase glycogen at a greater level compared classic protocol. Endeavour College of Natural Health 9

10 CHO Loading Challenges of CHO Loading as a protocol Consuming enough CHO Keeping energy and fat intake reasonable Managing fibre intake Dental hygiene (acidic fluids) Endeavour College of Natural Health 10

11 CHO Before Exercise Compared to fasting, consuming CHO before exercise increases glycogen levels and improves performance. Eating pre-exercise and during exercise may further improve performance. Pre-exercise CHO may enhance recovery Quantity: 2-4g/kg BW Timing: 2-4 hrs before event Type: Familiar and appealing (low fibre) ALWAYS TRIAL THIS BEFORE USING IT ON RACE DAY Endeavour College of Natural Health 11

12 Rebound Hypoglycaemia Rebound hypoglycemia (also known as reactive hypoglycemia) is a condition in which low blood sugar (below blood glucose levels of ~3 mmol/l, with some individuals being symptomatic already at blood sugar values of ~4 mmol/l) is induced by a combination of the timing of an athletes dietary intakes and the types of dietary intake, in conjunction with the timing of subsequent exercise. About 30% of athletes appear to be incredibly sensitive to having reactive hypoglycemia (Kuipers et al., 1999; Brun et al., 2001) Endeavour College of Natural Health 12

13 Rebound Hypoglycaemia The major mechanism for skeletal muscle glucose uptake and disposal involves the transmembrane transporter of glucose, which is called glucose transporter (GLUT4). GLUT4 needs to be present at the surface of the skeletal muscle cell (membrane) to bring glucose into the muscle. It has been shown that GLUT4 are stored in intercellular pools, and can migrate to the skeletal muscle membrane by two primary mechanisms: 1) insulin or 2) contraction. (Kuipers et al., 1999; Brun et al., 2001) Endeavour College of Natural Health 13

14 Rebound Hypoglycaemia When a well-trained athlete consumes a large amount of simple carbohydrates (high GI carbohydrates), which induces a very high insulin level coupled with muscle contraction, both pools of GLUT4 transporters migrate to the surface of the skeletal muscle membrane. This extreme concentration of GLUT 4 transporters at the skeletal muscle membrane then causes a rapid uptake of blood glucose, which causes an acute and immediate drop in blood glucose, causing hypoglycemia. (Kuipers et al., 1999; Brun et al., 2001) Endeavour College of Natural Health 14

15 Rebound Hypoglycaemia Normally, situations of decreasing blood glucose are offset by the counter-regulatory hormone glucagon, which increases the livers production of glucose into the blood stream to maintain a normal blood glucose concentration. However, the sensitivity to this situation is highly individual and some athletes will still experience acute bouts of hypoglycemia prior to the effects of glucagon increasing blood glucose again. (Kuipers et al., 1999; Brun et al., 2001) Endeavour College of Natural Health 15

16 Rebound Hypoglycaemia Possibly exacerbating this situation, is that well-trained endurance athletes not only have more GLUT4 transporters, but their GLUT4 transporters actually work more efficiently than non- trained individuals This is the exact opposite of type II diabetic and/or obese populations, where insulin sensitivity is diminished since GLUT4 transporters do not work efficiently, and thus these populations tend to have chronically high blood sugar levels. (Kuipers et al., 1999; Brun et al., 2001) Endeavour College of Natural Health 16

17 Rebound Hypoglycaemia Strategies for sensitive individuals: Avoid CHO in the 90mins before exercise Consume CHO only 5-10mins before the session/event commences Choose a moderate/low GI CHO food Have at least 60g of CHO (tolerance permitting) as <25g of CHO has been shown to induce rebound hypoglycaemia. Ease into the exercise if possible (e.g. warm up) Once the exercise has started, continue to ingest CHO. (Kuipers et al., 1999; Brun et al., 2001) Endeavour College of Natural Health 17

18 CHO After Exercise Rapid Glycogen Replenishment 1.2g/kg BW/hr for the first 4 hours after the event If less CHO is consumed, co-ingestion of protein ( g/kg BW/hr) along with the CHO will replenish glycogen level to a similar rate. High GI sources may be used in order to consume the recommended amount of CHO over the 4 hours. Endeavour College of Natural Health 18

19 Guidelines for CHO intake Before Exercise Situation Recommended CHO Intake General fuelling for events <90mins Normal intake not need to load CHO loading for events >90mins 7-12g/kg BW/day Pre-event fuelling 2-4g/kg BW 1-4hrs before the event. Endeavour College of Natural Health 19

20 Guidelines for CHO intake During Exercise Situation Recommended CHO Intake During Exercise <45mins Not needed During sustained high intensity exercise 45-75mins During endurance and intermittent exercise lasting 1-2hrs During ultra endurance exercise >2hrs Small amounts including mouth rinse 30-60g per hour Up to 90g/hr of multiple transportable sources Endeavour College of Natural Health 20

21 Guidelines for CHO intake After Exercise Situation Recommended CHO Intake Passive recovery Rapid recovery (<8hrs between fuel demanding sessions tournament/athletics meet) Usually daily intake over 24hrs would be sufficient 1.2g/kg BW/hr for the first 4 hours after event. Endeavour College of Natural Health 21

22 Sports Nutrition Guidelines What is the key nutrition goal to support athletes whilst exercising? Retrieved from: Endeavour College of Natural Health 22

23 Does CHO benefit training? Strong evidence that restoration of muscle glycogen stores are superior when athletes consume higher CHO intakes during the training diet Smaller evidence demonstrates that consuming a higher CHO intake on a daily basis improves performance Burke & Deakin, 2015 Retrieved from : Endeavour College of Natural Health 23

24 Does CHO benefit training? Why isn t the evidence stronger? Limited ability to detect performance gains Different dietary configurations of high vs moderate CHO Duration of studies Limited studies within athletic populations Daily CHO intake may not be necessary for their sport Compliance of high CHO intake may be low Burke & Deakin, 2015 Retrieved from: Endeavour College of Natural Health 24

25 Train Low, Compete High Glycogen loading has been known to increase endurance performance for many years (Bergstrom & Hultman, 1967). As a result, most athletes and coaches believe that training in a glycogen-loaded state is essential to optimal conditioning and performance. However, the validity of this philosophy is now being challenged. It is becoming clear that there are benefits to training in a glycogen-depleted state. Endeavour College of Natural Health 25

26 Train Low, Compete High In the low glycogen state, whole body metabolism shifts drastically. In humans, glycogen depletion results in increased systemic release of amino acids from muscle protein breakdown, increased fat metabolism, reduced pyruvate oxidation, and increased stress hormones such as cortisol and epinephrine As a result of these changes, it is not surprising that performance is negatively affected by low muscle glycogen. Endeavour College of Natural Health 26

27 Train Low, Compete High However, some have postulated that lower glycogen during training alters whole body substrate metabolism in a manner that stimulates the activation of cellular signaling pathways that might be involved in the muscular adaptation to training (Steensberg et al., 2002). Hansen et al. have shown that 10 weeks of training in a glycogen-depleted state resulted in an 85% greater increase in time to exhaustion compared with training with high glycogen. Endeavour College of Natural Health 27

28 Train Low, Compete High The reason for this greater increase in endurance was a larger increase important enzymes of fat metabolism. These results have now been confirmed in highly trained cyclists suggesting that, regardless of the athlete s training state, training in a glycogen-depleted state results in an increased capacity to use fat as a fuel during exercise. Endeavour College of Natural Health 28

29 Train Low, Compete High Hansen et al, 2005 Untrained subjects all consumed a high CHO diet (8g/kg BW) Followed a 10 week training program LEG ONE (TRAIN LOW) 2 training sessions per day every 2 nd day 2 nd training session conducted under low glycogen conditions LEG TWO (TRAIN HIGH) 1 training session every day Trained under normal glycogen conditions Train Low leg had improved muscle glycogen content, increased oxidative enzymes and significantly improved TTE. Endeavour College of Natural Health 29

30 Train Low, Compete High Since training in the glycogen-depleted state improves the capacity for fat oxidation, this type of training might be expected to have a glycogen sparing effect during competition leading to improved performance. While this might be true at low intensities (<70% whole body VO2max) exercise, it does not appear to have a positive effect on performance at higher intensities (>70% whole body VO2max) where CHO are the primary fuel source. Endeavour College of Natural Health 30

31 Train Low, Compete High What this means is that in long duration endurance competition (triathlon, marathon, road cycling), training in a glycogen-depleted state will have a positive effect on performance. However, in shorter, higher intensity events (10K run, time trial cycling, rowing), training in a glycogen-depleted state will have less of a performance benefit. Endeavour College of Natural Health 31

32 Train Low, Compete High One caveat is that for competitions such as world championships and Olympics. As heats are run prior to the finals, low glycogen training, and the resulting increase in the capacity to use fat as a fuel, may improve recovery and therefore have beneficial effects on subsequent performances. Endeavour College of Natural Health 32

33 Train Low, Compete High How to implement Train Low, Compete High: This can be accomplished by performing steady state exercise at ~70% of max for 30 minutes to 1 hour without consuming a CHO supplement. Following the depletion stage, a second session is performed. This session can be performed immediately, or following a fast of 1-3 hours. Endeavour College of Natural Health 33

34 Train Low, Compete High Ideally, the second session should include high intensity work as this type of training maximally activates the molecular targets that improve endurance performance. As with all training techniques, each athlete will have to determine whether training with low glycogen affects their recovery and therefore the overall intensity of their training. This highlights the benefits of an individualising nutrition strategies Endeavour College of Natural Health 34

35 Sleep Low? An alternative approach to prolong the duration of low CHO availability and potentially enhance and extend the time course of transcriptional activation of metabolic genes and their target proteins. This would also simultaneously conserving the training impulse to the working muscles is to have an athlete train-high and then sleep-low ( train-high, sleep-low ). Endeavour College of Natural Health 35

36 Sleep Low? In this model, an athlete would commence a HIT session in the evening with high glycogen availability. Then go to bed fasted, before undertaking a subsequent prolonged, submaximal training session the next morning and then re-feeding. Delaying energy (i.e. CHO) intake and extending the duration, an individual in a low glycogen state may augment the exercise diet-induced adaptation process. Endeavour College of Natural Health 36

37 Sleep Low? This would occur by delaying the re-synthesis of muscle (and liver) glycogen and up-regulating several key metabolic signaling pathways involved in mitochondrial biogenesis and lipid metabolism, compared to when individuals followed sports nutrition guidelines (i.e., high post-exercise CHO availability). Endeavour College of Natural Health 37

38 Summary The aim of the development of these protocols were to force the athlete to train with low muscle glycogen levels with the understanding that it promotes training adaptations (i.e. increases the activities of enzymes involved in energy metabolism and mitochondrial biogenesis) to a greater extent than when all workouts are undertaken with normal or elevated glycogen stores. Endeavour College of Natural Health 38

39 References AIS Sports Nutrition, last updated Feb Australian Sports Commission. Bergström, J., Hermansen, L., Hultman, E., & Saltin, B. (1967). Diet, muscle glycogen and physical performance. Acta Physiologica, 71(2 3), Burke, L., & Deakin, V. (2015). Clinical sports nutrition. (5 th ed.). Sydney, Australia: McGraw Hill. Brun, J. F., Dumortier, M., Fedou, C., & Mercier, J. (2001). EXERCISE HYPOGLYCEMIA IN NONDIABETIC. Diabetes Metab (Paris), 27, Kuipers, H., Fransen, E. J., & Keizer, H. A. (1999). Pre-exercise ingestion of carbohydrate and transient hypoglycemia during exercise. International journal of sports medicine, 20(04), Hansen, A. K., Fischer, C. P., Plomgaard, P., Andersen, J. L., Saltin, B., & Pedersen, B. K. (2005). Skeletal muscle adaptation: training twice every second day vs. training once daily. Journal of Applied Physiology, 98(1), Steensberg, A., Hall, G., Keller, C., Osada, T., Schjerling, P., Klarlund Pedersen, B.,... & Febbraio, M. A. (2002). Muscle glycogen content and glucose uptake during exercise in humans: influence of prior exercise and dietary manipulation. The Journal of physiology, 541(1), Endeavour College of Natural Health 39

40 COMMONWEALTH OF AUSTRALIA Copyright Regulations 1969 WARNING This material has been reproduced and communicated to you by or on behalf of the Australian College of Natural Medicine Pty Ltd (ACNM) trading as Endeavour College of Natural Health, FIAFitnation, College of Natural Beauty, Wellnation - Pursuant Part VB of the Copyright Act 1968 (the Act). The material in this communication may be subject to copyright under the Act. Any further reproduction or communication of this material by you may be the subject of copyright protection under the Act. Do not remove this notice.