Another important factor for performance, especially in warm conditions, is hydration. Severe dehydration will have a negative impact on performance, causing you to fatigue and slow down. We can generally tolerate a certain level of dehydration (a 2-3% reduction in body weight), but anything greater than this will have a negative impact.

 

What is the optimal drinking strategy? There is a high level of individual variation in how much we sweat during exercise. We all differ based on training status, hydration status, ambient weather conditions, terrain, clothing etc. The best strategy is to measure your own individual sweat rate. This is relatively easy to do.  For your convenience, I have created a sweat rate and re-hydration calculator on my website at the following link:

 

http://www.metabolise.ie/?tools.html?tools/sweat_rate.html

 

To calculate your sweat rate, you will need to measure the following:

 

  • Weigh yourself (preferably nude) before training/competition.
  • Weigh yourself (preferably nude) after training/competition and after towelling down.
  • Measure the amount of fluid consumed.
  • Estimate any urination between before and after weigh in.
  • Duration of training session or competition.

 

With this information at hand, you can calculate your sweat rate.  Ideally, you will exercise at race pace for one hour (possibly shorter for swimming). This will allow you to estimate your average sweat loss. You can do this for the three different disciplines, as it is likely you will sweat at different rates depending on the type of activity you’re doing. Ideally, you would perform this test during  a warm-up race to make the figure as realistic as possible.

 

With this information at hand, you can then calculate your ideal rehydration rate. The calculator allows you to factor in an acceptable level of dehydration. This is set at 2%, which is the maximum accepted weight loss without a negative effect on performance.

 

If you want to take it to a professional level, determine your sweat rates in different environmental conditions (cold, moderate, hot weather) so that regardless of the weather on the day, you will know what your ideal hydration strategy is for those conditions.

 

One important consideration with hydration is hyponotraemia , which is a potentially serious medical condition. Hyponotraemia is  caused by consuming too much fluid, resulting in a change in the composition of blood plasma and potentially fatal knock on effects (e.g. swelling of the brain). This generally occurs for beginners or slow competitors who consume excess fluids (i.e. drink more fluid than they lose through sweating) during a triathlon. This is one reason why it is a good idea to measure your sweat rate and have a hydration plan in place. As well as keeping you hydrated, it will prevent you from developing hyponotraemia.

 

One last thing to mention is caffeine, which has the potential to enhance your performance.  Caffeine works by altering your perception of how hard you’re working. I can testify to the power of caffeine as it has helped me finish a long hard ride on more than one occasion.

 

Caffeine can be consumed in a number of ways – by taking caffeine tablets in measured doses, by eating a gel which contains caffeine or by drinking coffee or Coke. One point to be aware of is that if you are a habitual coffee drinker than you may not get this performance enhancing effect. The best way to ensure that you get a boost is to stop consuming coffee or caffeine containing products 4-5 days before your event. This “wash-out” period will allow you to get the best effect from caffeine when you take it during an event. As with all nutrition strategies, experiment in training to see if this is right for you.

D.I.Y. Energy Drinks for Triathlon

The two best ways to increase your carbohydrate intake are through fluids and food. Fluids have the advantage of hydrating you as well as providing energy. Many sports drinks and water soluble powders are commercially available which are ready off the shelf. However, I prefer to make my own drinks for the following reasons:

  • I can control the amount of carbohydrate, the taste and adjust to my preferences
  • It’s cheaper to make your own.

If you decide to make your own sports drink, you will need to buy maltodextrin or glucose powder and fructose powder. You can buy 1kg packets of maltodextrin (approx. €5) and fructose (approx. €8) online. This will be enough to last you several weeks.

To prepare your own sports drink, you will need the following ingredients:

  • 50g Maltodextrin
  • 25g Fructose
  • 1L water
  • 1g table salt
  • Flavouring – Miwadi/Robinsons

It is important to use the measurements outlined as this is the optimal blend. Too much maltodextrin/fructose may cause discomfort such as bloating, cramping and diarrhoea. Too little carbohydrate and you won’t be delivering the carbohydrate at the optimum rate. The combination of fructose and maltodextrin allows the maximal rate of absorption of carbohydrate compared to using either on its own. Another added benefit is that the addition of fructose allows greater water absorption, promoting greater hydration. Adding a small amount of salt is also important as the sodium in the salt allows greater absorption of water in the intestine.

Sports gels are another great way of increasing your carbohydrate intake during the cycle (and run leg) as they are small and easy to carry. As with sports drinks, you should be looking at the different types of carbohydrate contained in the gels. In general, fructose in combination with glucose, maltodextrin or galactose will allow the maximum rate of delivery of carbohydrate to your working muscles. The optimum ratio is two parts maltodextrin,glucose or galactose to one part fructose.

Not to be under-estimated is taste. When out on a long ride, I find that I look forward to eating my gels/bars as a treat. However, many gels are tasteless. I find that eating gels with a pleasant taste gives me an extra psychological lift! One brand that I can recommend is the TORQ brand of gels, which are very tasty and come in a variety of flavours. If sports drinks and gels are beyond your budget, foods such as ripe bananas, figs and raisins are also high in carbohydrate and might be a low cost alternative.

 

The maximal rate of which your body can absorb and use carbohydrates from drinks, gels and food is between 60-90g/hour. It is a good idea to experiment with different combinations of fluid, gels and foods during training and warm-up races to find the right combination for you. It is important to realise that we are all individuals and what works for your training partner might not work for you.

 

One common mistake by beginners is to eat too much on the bike leg. When completing the running leg, there is a lot of fluid and food sloshing around in the stomach. This can lead to gastro-intestinal discomfort, with feelings of bloating and nausea being common. Again, use your training to determine the optimal feeding strategy on the cycle leg, without compromising the run leg.

 

Because, there are many different types of triathlon events, and your training duration varies, the below table will help you to decide which is the best intake rate and type of carbohydrate to ingest.

Event Duration Carbohydrate Requirement Recommended Intake Carbohydrate Type Single Carbohydrate Multiple Types of Carbohydrate
< 30 min None None None None None
30-75 min Very Small Amounts Carbohydrate Mouth Rinse Most forms of carbohydrate OK OK
1 – 2 hr Small amounts Up to 30g/hr Most forms of carbohydrate OK OK
2 – 3 hr Moderate amounts Up to 60g/hr Ingestion of single carbohydrates (e.g. glucose, maltodextrin) OK, but not optimal OK
>2.5 hr Large amounts Up to 90g/hr Only multiple types of carbohydrates (e.g. maltodextrin and fructose) Not optimal OK

Taken from: Juenkendrup, A. (2011). Nutrition for Endurance Sports: Marathon, triathlon and Road Cycling. Journal of Sports Sciences, 29(S1), S91-S99.

 

Some interesting research that is just emerging is that your digestive system is trainable. By consuming carbohydrate during training, your body becomes better at absorbing and burning carbohydrate as you exercise. Therefore, train as you mean to compete and this includes incorporating race eating strategies into your training.

Hi there,

Last week I posted an assignment I wrote about high fat diets and endurance performance. The post was technical and may be understandable for sport scientists, but may not be easily understood by the lay person. So, in this post, I will try and explain the rationale and translate into practical guidelines.

Firstly, the protocol is that for 5-6 days prior to an endurance event (probably lasting longer than 1.5 hours – a marathon or half triathlon) you load up on fat in your diet. In practical terms, this equates to around 70% of calories from fat. Or, if you have the ability to weigh and monitor your food intake, this equates to 4.6g Fat/kg Body Weight/day. On the day before the event, we then change strategy and consume a high carbohydrate diet (70% calories or around 11g Carbohydrate/kg Body Weight/Day). This has the bonus of topping up our body’s carbohydrate (i.e. glycogen) stores.

The outcome of this strategy is that your body becomes more efficient and adept at burning fat. This is beneficial because we have huge amounts of energy stored as fat in our body, whereas we have limited amounts of carbohydrate. In endurance events of duration longer than 1.5 hours, the limited supplies of carbohydrate in our body may become an issue and may compromise performance. However, if we follow a high-fat diet, we tap into the bodies nearly unlimited supply of fat.

All well and good. But there is a caveat. By eating a high fat diet and turning up our bodies ability to burn fat as a source of energy, we compromise our body’s ability to burn carbohydrate. There is a trade off. Research has shown that high intensity performance is compromised in this scenario. Carbohydrate is a great source of energy at high exercise intensities, whereas fat isn’t. So, as a result, when we really start to push it in training or competition, our bodies ability to release energy from carbohydrate is dampened.

So, on a practical level, this is what I suggest. If finishing is the main outcome for you, then a high fat diet may help you to avoid the unpleasant consequences of “hitting the wall” or “the bonk”. You should be able to utilise your body’s store of fat to complete the event.

If, however, you have designs of winning or placing highly and you will really push yourself during the event, then I would suggest not following this strategy as you may not be able to give that high intensity spurt towards the end. In this case, I would advise some other strategies which will train your body to burn fat without compromising high intensity performance.

One of these strategies is the “train-low, compete high” scenario. In this, you train when your bodies carbohydrate levels are low. This trains your body to become more efficient at burning fat without compromising your ability to burn carbohydrate at high intensity.

This can be achieved in a number of ways:

  • Training first thing in the morning without having a breakfast.
  • Training twice a day. Eat very little carbohydrate between your first and second training session so that your carbohydrate stores are depleted.
  • On long training runs/cycles, do not consume any carbohydrate.

However, these are adavanced tactics. They should not be used by beginners and should only be used by advanced athletes sparingly (i.e. once a week).

Thanks for reading,

Kevin – Metabolise Sports Nutrition

Performance and Health Implications of High Fat Diets on Endurance Performance.

Athletes experiment with nutritional and training strategies to give themselves a competitive edge over rivals. Although high carbohydrate (H-CHO) diets are typically recommended for endurance athletes, some athletes have ignored this advice, consumed high fat (H-FAT) diets and have competed successful. Mark Allen and Jonas Colting are examples of two tri-athletes who have successfully followed H-FAT diets and won Iron Man and Ultra Man World Championships. Sparing limited glycogen reserves and increasing fat oxidation may be a viable strategy for improved endurance performance.

One of the first studies examining the effect of a high fat (H-FAT) diet on performance was undertaken by Phinney, Bistrian, Evans, Gervino & Blackburn (1983). Five endurance trained athletes consumed either a H-FAT (85% energy) or high carbohydrate (H-CHO) (66% energy) diet for four weeks. During a performance test after dieting, there was a decrease in the Respiratory Exchange Ratio (RER), a three-fold drop in glucose oxidation and a four-fold reduction in muscle glycogen use on the H-FAT diet, indicative of an increased rate of fat oxidation. Similar results were reported by other investigators (Goedecke, Christie, Wilson, Dennis, Noakes, Hopkins & Lambert, 1999; Helge, Watt, Richter, Rennie & Kiens, 2001).

Although H-FAT diets promote fat metabolism and glycogen sparing, one of the problems encountered by early investigators was that muscle glycogen was substantially reduced after a high fat diet due to low carbohydrate intake (Lambert, Speechly, Dennis & Noakes, 1994), which may negatively affect endurance performance (Bergström, Hermansen, Hultman, & Saltin, 1967). Therefore, later research utilised a dietary periodisation strategy, whereby glycogen loading would be undertaken after a period of H-FAT consumption, to replenish glycogen stores. Burke, Angus, Cox, Cummings, Febbraio, Gawthorn, Hawley, Minehan, Hargreaves & Hawley (2000) reported the effects a shorter adaptation period (5 days) with CHO restoration, comparing H-FAT (4g/kg/day) and H-CHO (9.6g/kg/day).  During 2 hours steady state exercise at 70% VO2 max, RER was reduced, fat oxidation increased and CHO oxidation decreased. Thus, even with CHO restoration and availability, exercising muscle preferentially oxidised fat as a fuel substrate.

Therefore, H-FAT diets promote fat oxidation and glycogen sparing during exercise. How might this work? Many of the cellular adaptations associated with H-FAT diets include increased enzymes involved in beta oxidation (Helge & Kiens, 1997), increased fatty acid transporters (Glatz, Luiken & Bonen, 2010) and increased mRNA concentrations of proteins involved in fatty acid transport and metabolism (Cameron-Smith, Burke, Angus, Tunstall, Cox, Bonen, Hawley & Hargreaves, 2003). Therefore, H-FAT diets up-regulate the metabolic machinery for the transport and oxidation of fats into the muscle cell and mitochondria.

How might H-FAT diets affect performance? Helge, Richter & Kiens (1996) divided subjects into H-CHO (65% energy) or H-FAT (62% energy) group for seven weeks followed by carbohydrate restoration in week 8. Subjects trained 3-4 times per week during the study period. After 7 weeks, time trial to exhaustion (TTE) at 81% of pre-training VO2 max increased from a mean of 35 mins to 102 mins in the H-CHO and 65 mins in H-FAT, with the improvement in performance significantly greater in the H-CHO group versus the H-FAT group. Even with a CHO restoration protocol in week 8, TTE improved slightly in the H-FAT group (77 mins) but was still significantly less than H-CHO TTE.

Other studies have demonstrated improvements in performance on H-FAT diets. Phinney et al. (1983) demonstrated that although there was no difference in time to exhaustion (TTE – cycle ergometer test at 62-64% of VO2 max) between the H-FAT and L-FAT diets, TTE increased by four minutes in H-FAT compared to baseline. However, closer inspection of the results revealed that one athlete had an abnormally large increase in TTE in week five while the other subjects either had no change or a decrease in performance.

Lambert et al. (1994) demonstrated an improvement in a cycle to exhaustion at 50% Peak Power Output (PPO) after a two week H-FAT (70% total energy) compared to H-CHO (74% total energy). There was no difference in cycle to exhaustion at 85% PPO. Carey, Staudacher, Cummings, Stepto, Nikolopoulos, Burke & Hawley (2001) examined the effects of H-CHO (11 g/kg/day  CHO, 1 g/kg/day FAT) or an isoenergetic high-fat diet (2.6 g/kg/day CHO, 4.6 g/kg/day FAT) diet for 6 days followed by CHO restoration on time trial performance. After cycling for 4 hours at 65% peak VO2 uptake, subjects on the H-FAT diet maintained an 11% non-significant (P=0.11) higher power output in a 1 hour time-trial task compared to H-CHO.

Therefore, the results from the effects of H-FAT diets on performance are equivocal. However, one observation is that performance in low and medium intensity exercise is enhanced. This might be expected, as substrate oxidation at these intensities is predominately fat (Van Loon, Greenhaff, Constantin-Teodosiu, Saris & Wagenmakers, 2001). If we look at exercising at higher intensities, a different picture emerges.

Stepto, Carey, Staudacher, Cummings, Burke & Hawley (2002) compared a three day H-FAT (4.6g/kg/day) or H-CHO (11g/kg/day) diet on high intensity interval exercise (8×5 min bouts at 86% VO2 peak) and reported higher Rate of Perceived Exertion (RPE) in the H-FAT versus H-CHO. Havemann, West, Goedecke, Macdonald, St Clair Gibson, Noakes & Lambert (2006) examined the effects of a six day H-FAT (68% energy) or H-CHO (68% energy) diet followed by carbohydrate restoration on a 100km TT interspersed with one kilometre sprints. This may be a more realistic scenario for elite performance compared to constant lower intensity performance trials. The one kilometre sprint power output was significantly lower in the H-FAT diet compared with the H-CHO diet.

Stellingwerff, Spriet, Watt, Kimber, Hargreaves, Hawley & Burke (2006) measured the effects of either a five day H-FAT (4.6g/kg/day) or H-CHO (10.3g/kg/day) diet, followed by carbohydrate restoration on 1 min sprint performance. Pyruvate Dehydrogenase activity was significantly reduced at rest and during low and high intensity exercise and estimated rates of glycogenolysis were reduced in H-FAT condition. This suggests that H-FAT diets work not through glycogen sparing but through glycogen impairment.

Intramuscular Triglycerides (IMTG) have been identified as an important fuel substrate during exercise, even at power outputs approaching 85% VO2 max in trained athletes. If undertaking high training volumes on consecutive days, athletes may need to consume higher than normal fat intakes (35-57% of energy) in order to replenish IMTG (Spriet & Gibala, 2004). Decombraz (2003) has suggested consuming a H-CHO diet in the initial 6-8 hours of recovery, with fat content increasing thereafter.

The World Health Organisation (2003) has recommended fat intakes of 15-35% of total energy intake for optimal health. Long-term H-FAT diets are associated with development of obesity, coronary heart disease and certain cancers (Manore, Meyer, & Thompson, 2009) and thus would not be recommended as a lifestyle choice. Acute fat intake results in transient suppression of muscle glucose uptake and muscle glycogen synthesis (Boden, 1997) and in the long-term may lead to insulin resistance, although this may be attenuated in endurance trained athletes (Goodpaster, He, Watkins & Kelley, 2001). However, training while fasting, during periods of hyper-caloric H-FAT intake, can improve whole body glucose tolerance and markers of insulin sensitivity (Van Proeyen, Szlufcik, Nielens, Pelgrim, Deldicque, Hesselink, Veldhoven, & Hespel, 2010). Training 3-4 times per week over seven weeks on a H-FAT (62% E) diet compared to a H-CHO (65% E) has been shown to reduce Natural Killer cell activity (Pedersen, Helge, Richter, Rohde & Kiens, 2000). This may compromise innate immunity and increase the risk of athlete infection. Therefore, there may be several adverse health consequences with consuming H-FAT diets.

From the research reviewed, it would be prudent to form the opinion that H-FAT diets, while increasing the ability to oxidise fat and spare glycogen at lower exercise intensities, reduces the ability to oxidise glucose at high intensities. Given that the outcome of all Olympic endurance events are decided at exercise intensities above 85% VO2 max (Joyner & Coyle, 2008), a compromised ability to oxidise glucose at high intensities would have negative consequences on elite performance. Long term H-FAT intake may compromise adaptations to training and may negatively affect health, although some of these ill effects may be attenuated by training. Reviews of the relevant literature do not recommend high fat diets to enhance performance (Hargreaves, Hawley & Jeukendrup, 2004) or training (Burke, Kiens & Ivy, 2004).

Using different nutrition practices (e.g. carbohydrate restriction before/during/after training – Hawley & Burke, 2010; Van Proyen, Szlufcik, Nielens, Ramaekers, & Hespel, 2011) or performing high-intensity interval training (Burgomaster, Howarth, Phillips, Rakobowchuk, MacDonald, McGee, & Gibala, 2008) may replicate many of the cellular and metabolic adaptations associated with H-FAT diets. High rates (1.75g/min) of exogenous carbohydrate oxidation can be achieved during exercise using multiple transportable carbohydrates (Jeukendrup, 2010), negating the need to protect glycogen stores. Short-term carbohydrate loading can increase muscle glycogen stores two-fold (Fairchild, Fletcher, Steele, Goodman, Dawson & Fournier, 2002). Strategies other than H-FAT diets are available to athletes to promote fat oxidation and boost glycogen stores without the need to compromise high intensity performance or health.

Reference

Bergström, J.,  Hermansen, L., Hultman, E., & Saltin, B. (1967). Diet, muscle glycogen and physical performance. Acta Physiologica Scandinavica, 7(2-3), 140-150.

Boden, G. (1997). Role of fatty acids in the pathogenesis of insulin resistance and NIDDM. Diabetes, 46(1), 3-10.

Burgomaster, K.A.,  Howarth, K.R.,  Phillips, S.M.,  Rakobowchuk, M.,  MacDonald, M.J., McGee, S.L. & Gibala, M.J. (2008). Similar metabolic adaptations during exercise after low volume sprint interval and traditional endurance training in humans.  Journal of Physiology, 586(1), 151-160.

Burke, L.M., Angus, D.J., Cox, G.R., Cummings, N.K., Febbraio, M.A., Gawthorn, K., Hawley, J.A., Minehan, M., Martin, D.T., & Hargreaves, M. (2000). Effect of fat adaptation and carbohydrate restoration on metabolism and performance during prolonged cycling. Journal of Applied Physiology, 89(6), 2413-2421.

Burke, L.M., Kiens, B., & Ivy, J.F. (2004). Carbohydrates and fat for training and recovery. Journal of Sports Sciences, 22, 15-30.

Cameron-Smith, D., Burke, L.M., Angus, D.J.,  Tunstall, R.J., Cox, G.R., Bonen, A., Hawley, J.A., & Hargreaves, M. (2003). A short-term, high-fat diet up-regulates lipid metabolism and gene expression in human skeletal muscle. American Journal of Clinical Nutrition, 77(2), 313-318.

Carey, A.L., Staudacher, A.M., Cummings, N.K., Stepto, N.K., Nikolopoulos, V., Burke, L.M., & Hawley, J.A. (2001). Effects of fat adaptation and carbohydrate restoration on prolonged endurance exercise. Journal of Applied Physiology, 91(1), 115-122.

Decombaz, J. (2003). Nutrition and recovery of muscle energy stores after exercise. Sportmedizin und Sporttraumatologie, 51(1), 31–38.

Fairchild, T.J., Fletcher, S., Steele, P., Goodman, C., Dawson, B., & Fournier, P.A. (2002). Rapid carbohydrate loading after a short bout of near maximal-intensity exercise. Medicine and Science in Sports and Exercise, 34(6), 980-986.

Goedecke, J.H., Christie, C., Wilson, G., Dennis, S.C., Noakes, T.D., Hopkins, W.G., & Lambert, E.V. (1999). Metabolic adaptations to a high-fat diet in endurance cyclists. Metabolism, 48(12), 1509-1507.

Goodpaster, B.H., He, J., Watkins, S., & Kelley, D.E. (2001). Skeletal muscle lipid content and insulin resistance: evidence for a paradox in endurance-trained athletes. Journal of Clinical Endocrinology Metabolism, 86(12), 5755–5761.

Glatz, J.F.,  Luiken, J.J., & Bonen, A. (2010). Membrane fatty acid transporters as regulators of lipid metabolism: Implications for metabolic disease. Physiological Review, 90(1), 367-417.

Hargreaves, M., Hawley, J.A., & Jeukendrup, A. (2004). Pre-exercise carbohydrate and fat ingestion: effects on metabolism and performance. Journal of Sports Sciences, 22, 31-38.

Havemann, L.,  West, S.J.,  Goedecke, J.H., Macdonald, I.A.,  St Clair Gibson, A., Noakes, T.D. & Lambert, E.V. (2006). Fat adaptation followed by carbohydrate loading compromises high-intensity sprint performance. Journal of Applied Physiology, 100(1), 194-202.

Hawley, J.A., & Burke, L.M. (2010). Carbohydrate availability and training adaptation: Effects on cell metabolism. Exercise and Sport Sciences Reviews, 38(4), 152-160.

Helge, J.W., & Kiens, B. (1997). Muscle enzyme activity in humans: role of substrate availability and training. American Journal of Physiology, 272(5), 1620-1624.

Helge, J.W., Richter, E.A.,  & Kiens, B. (1996). Interaction of training and diet on metabolism and endurance during exercise in man. The Journal of Physiology, 492(1), 293-306.

Helge, J.W., Watt, P.W., Richter, E.A., Rennie, M.J., & Kiens, B. (2001). Fat utilization during exercise: adaptation to a fat-rich diet increases utilization of plasma fatty acids and very low density lipoprotein-triacylglycerol in humans. The Journal of Physiology, 537, 1009-1020.

Jeukendrup, A. (2010). Carbohydrate and exercise performance: the role of multiple transportable carbohydrates. Current Opinion in Clinical Nutrition and Metabolic Care, 13(4), 452-457.

Joyner, M.J., & Coyle, E.F. (2008). Endurance exercise performance: the physiology of champions. Journal of Physiology, 586(1), 35-44.

Lambert, E.V., Speechly, D.P., Dennis, S.C., & Noakes, T.D. (1994). Enhanced endurance in trained cyclists during moderate intensity exercise following 2 weeks adaptation to a high fat diet. European Journal of Applied Physiology and Occupational Physiology, 69(4), 287-93.

Manore, M.M., Meyer, N.L. & Thompson, J. (2009). Fat as a fuel for exercise. In M.M. Manore, N.L. Meyer and J. Thompson (Eds.), Sport nutrition for health and performance (2nd ed.) (pp. 77). Champaign, IL: Human Kinetics.

Pedersen, B.K., Helge, J.W., Richter, E.A., Rohde, T., & Kiens, B. (2000). Training and natural immunity: effects of diets rich in fat or carbohydrate. European Journal of Applied Physiology, 82(1-2), 98-102.

Phinney S.D., Bistrian, B.R., Evans, W.J., Gervino, E., & Blackburn, G.L. (1983). The human metabolic response to chronic ketosis without caloric restriction: preservation of submaximal exercise capability with reduced carbohydrate oxidation. Metabolism, 32(8), 769-776.

Spriet, L.L., & Gibala, M.J. (2004). Nutritional strategies to influence adaptations to training. Journal of Sports Sciences, 22, 127-141.

Stellingwerff, T.,  Spriet, L.L.,  Watt, M.J., Kimber, N.E., Hargreaves, M., Hawley, J.A., & Burke, L.M. (2006). Decreased PDH activation and glycogenolysis during exercise following fat adaptation with carbohydrate restoration. American Journal of Physiology –  Endocrinology and Metabolism, 290(2), 380-388.

Stepto, N.K., Carey, A.L.,  Staudacher, H.M.,  Cummings, N.K., Burke, L.M.,  & Hawley, J.A. (2002). Effect of short-term fat adaptation on high intensity training. Medicine and Science in Sports and Exercise, 34(3), 449-455.

Van Loon, L.J.C.,  Greenhaff, P.L., Constantin-Teodosiu, D., Saris, H.M., &  Wagenmakers, A.J.M. (2001). The effects of increasing exercise intensity on muscle fuel utilisation in humans.  Journal of Physiology, 536, 295-30

Van Proeyen, K., Szlufcik, K., Nielens, H., Pelgrim, K.,  Deldicque, L., Hesselink, M., Van Veldhoven, P.P., & Hespel, P. (2010). Training in the fasted state improves glucose tolerance during fat-rich diet. The Journal of Physiology, 588(21), 4289-4302.

Van Proeyen, K., Szlufcik, K., Nielens, H., Raemakers, M., & Hespel, P. (2011). Beneficial metabolic adaptations due to endurance exercise training in the fasted state. Journal of Applied Physiology, 110(1), 236-245.

World Health Organisation. (2003). Diet, nutrition and the prevention of chronic diseases. Geneva, Switzerland: WHO Technical Report Series. Retrieved July 20, 2011 from http://whqlibdoc.who.int/trs/WHO_TRS_916.pdf

Metabolise Sports Nutrition

Hello,

It being winter here in the northern hemisphere, and with many athletes getting back into training after the Christmas break, thoughts turn to how to prevent illnesses in this vulnerable timeframe. Athletes are liable to dose up on additional vitamin and minerals in order to boost their immune systems and to help prevent colds, flus, URTIs etc.

It therefore came as a surprise to me to read this review which looked at the effects of vitamin and mineral supplementation on illness prevention in athletic populations. The findings will not be pleasant reading for the manufacturers of vitamin and mineral supplements.

The authors concluded that the following supplements have no proven benefits in preventing illness in athletes:

  • Vitamin E
  • Vitamin C
  • Multiple vitamin and minerals
  • Glutamine
  • BCAAs
  • Fish Oil (N-3 PUFAs)
  • Beta-glucan
  • Herbal Supplements (e.g. ginseng)

The jury is still out on the following supplements:

  • Bovine Colostrums
  • Probiotics

The only supplements that the authors recommend are carbohydrate (which athletes will probably be eating large quantities of anyway), and quercitin, a flavaoid widely found in fruit, vegetables, grains and leaves. It seems that the best way to prevent those winter sniffles is to eat a balanced and varied diet.

Kevin Beasley

This being my first blog post, and the last day of 2011, I would like to begin with a brief review of the most thought provoking nutrition book that I’ve read this year. The book is called “Good Calories, Bad Calories” by Gary Taubes.

Taubes builds a compelling case, based on scientific evidence, that everything we thought we knew about how the human body regulates weight is wrong. The basic premise is that all calories aren’t equal, and it is the increase in carbohydrate consumption – and especially refined carbohydrates – that have been the ignition for the obesity crisis. Eating carbohydrates has an inpact on the release of insulin. Chronic consumption of refined carbohydrates results in abnormalities in the release of insulin and our bodies ability to deal with carbohydrates. As a result, chronic elevation of insulin results in increased storage of  carbohydrates in fat tissue and a decreased ability of our bodies to burn fat.

To summarise some of the fascinating insights in the book:

  • Obesity is actually a disease of malnutrition. Our fat tissue takes all the energy for itself, meaning that the rest of the bodies cells are starved.
  • Obesity causes tiredness/laziness and over-consumption of food – and not the other way around.
  • The body has an intrinsic, finely-tuned system that regulates food intake in response to our energy expenditure and needs. This system is disrupted by over-consumption of refined carbohydrates.
  • For sedentary people, the food pyramid is upside down. We should be consuming more fats and protein, and less carbohydrate. This is probably the one single thing that has provoked the obesity crisis.

While this book is aimed at the obesity crisis, and ways of dealing with it, I believe the implications are also relevant for sports nutrition, especially for weight category sports. Strategies can be designed, based on this book, for safe and effective ways of obtaining the ideal physique for your sport. It goes without saying that reduction in carbohydrate intake is the main basis of this strategy.

This book is a weighty tome, weighing in at over 600 pages, and is probably suitable for someone with a scientific background. However, a more basic version of this book, called “Why we get fat – and What to do about it” is available and may be more suitable for the layperson or general public.

Overall, whether you are a scientist, dietitian, nutritionist or Joe Bloggs, I would highly recommend reading this book. It will change the way you view food….

Happy New Year,
Kevin Beasley