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An Optimum Fluid and Nutrient Intake Will Improve your Potential Marathon Performance

In a fascinating study on a group of 344 marathon runners competing in the Los Angeles Marathon (Butteworth, Nieman, Butler, and Herring, 1994), each athlete recorded what and when they ate and drank over three days. What emerged was that a significant amount of their calorific intake (24-35%) was from snacking, and over half their calories were consumed in the evening.

In the twenty plus years since that study was carried out our knowledge of sports nutrition has moved on substantially. First we will look at how choosing the optimum carbohydrate and fluid intake improves marathon performance; we will then compare the benefits of supplementing carbohydrate with protein and ribose; and finally we will look at the role of iron and how a medium to high iron diet can keep your iron levels in balance.

 

The effect of carbohydrate and fluid intake on marathon performance

Clearly, when running a marathon athletes need considerable amounts of carbohydrate and fluid. Without this performance will soon deteriorate, but how do you know how much of each is needed to achieve optimum performance? While laboratory tests can come up with solutions, do they work in real world endurance events such as marathons?

·         Fluids – It is well known that you need to maintain your fluid balance during any exercise that lasts for an hour or more otherwise you will dehydrate, your body temperature will rise, and your performance will be impaired. Losing just 2% of your body mass by dehydration is enough to reduce your physical and cognitive abilities (Shirreffs & Sawka, 2011). However, there is a difference between elite athletes and recreational marathon runners; winners of marathons usually loose more than 3% of their body mass. Considered advice is to drink 0.4 to 0.8 litres per hour.

·         Carbohydrate – Consuming carbohydrate during prolonged exercise can improve performance. As well as maintaining the carbohydrate store it is also needed to maintain blood glucose levels. If sufficient glucose is consumed to achieve this, then performance is enhanced. The recommended carbohydrate intake is around 60 grams per hour when consumed as just glucose and up to 90 grams per hour when consumed as glucose and fructose.

In reality, marathon runners generally consume less than the recommended quantities of fluid and carbohydrate while running a marathon; 0.35 litres per hour of fluid and 35 grams per hour carbohydrate are more typical than the levels suggested above.

The big question is would marathon performance improve if runners increased their consumption of fluid and carbohydrate to the recommended levels. Hansen et. al. (2014) put this to the test at the 2013 Copenhagen marathon.  It was known that that endurance trained cyclists performed better by around 6% when they consumed the recommended amounts than they did when they chose their own intakes. However, there are significant differences between cycling and running in a marathon.

Two groups of runners were compared. One group selected their own intake, while the other took the recommended quantities. However, the self-selecting group chose a higher fluid intake than was expected and they were as well hydrated as the other group, so dehydration was no longer an issue; there was no significant difference in body mass loss between the groups; both lost less than 2%.

On the other hand, there was a considerable difference between the groups in terms of carbohydrate intake, the freely selecting group choosing to consume much lower amounts. This had a huge impact on the relative performance. During the first five of the ten sections of the marathon the two groups had similar running velocities, however, during the second half the performance of the self-selecting group deteriorated quickly and, by the ninth stage, the running velocity of the freely selecting group had fallen to around 10 km/hour while the other group had maintained a running velocity of around 11.5 km/hour. The difference in average finishing time between the groups was 11 minutes.

 

The benefits of carbohydrate, protein and ribose repletion supplements

The reason why it is generally recommended that athletes ingest carbohydrates after exercise is that doing so replenishes glycogen stores so that glycogen will be available for subsequent exercise, with the possibility of increasing performance. This particularly applies when sporting events and exercise are engaged in frequently, for instance in tournaments and long term endurance events such as marathons, where fast glycogen resynthesis is necessary for achieving peak performance.

It isn’t just carbohydrate that is needed. For instance:

·         Often a combination of carbohydrates and protein is recommended as being better than carbohydrate alone for helping muscle recovery, and this has been demonstrated to be effective for immediate recovery within five hours of glycogen depleting exercise (Williams et.al., 2003).

·         Supplemental ribose may also help maintain and quickly synthesize energy stores by increasing the cellular concentration of ATP and adenosine diphosphate. Particular benefits of ribose are improving the function of the heart muscle, reduce cramping, and increase the tolerance to exercise.

So what is the effect of taking all three supplements: carbohydrate, protein and ribose? The effects of combining these supplements were compared with just ingesting carbohydrates on aerobic capacity, endurance performance, and body composition over an 8-week aerobic training program (Cramer et. al., 2012). Tests on 32 cyclists were made before commencement of training, then at 3 weeks, 6 weeks and after training.

The largest differences between the supplements were on time to exhaustion. The average time to exhaustion after completing training improved by around an additional 33% in athletes who drank the carbohydrate-protein and ribose supplement; a huge improvement in performance.

 

Iron in the soul

Iron levels are crucial; an iron imbalance or deficiency impairs performance significantly. Iron has many roles: it enables the transport of oxygen through the blood to the tissues; it is involved with storing oxygen in the muscles; and it is essential in the oxidative regeneration of ATP. Unfortunately, iron deficiency is common in athletes who compete in endurance events such as distance running (Anschuetz Rodgers &Taylor, 2010)

Changes in iron balance often occur as a result of training for endurance sports. Usually we lose around 1 mg of iron a day, but that amount doubles in endurance athletes. This iron must be replaced to maintain health and performance either by taking iron supplements or through our diet. There are two kinds of iron ion food:

·         Heme iron in meat, fish and poultry

·         Non-heme iron in vegetables, nuts, beans, cereals and fruits

Does choosing an iron rich diet allow endurance athletes to replenish their iron levels sufficiently and thus improve their performance? To test this Anschuetz et al (2010) looked at the impact of low to medium iron diets and medium to high iron diets on 17 middle distance runners and 8 non-runners as a control. They found that the iron levels were significantly higher in athletes on a medium to high iron diet.

The message is clear – marathon runners should choose an iron rich diet.

 

Finally

If you are competing in a marathon, it is clear that by choosing the right diet and ensuring that you consume adequate fluid and appropriate carbohydrate, protein and ribose supplements will improve your potential performance. This applies to equally to recreational runners as it does to elite athletes.

 

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    References

    Anschuetz S, Rodgers C, Taylor A, (2010) Meal Composition and Iron Status of Experienced Male and Female Distance Runners, J Exerc Sci Fit , 8 (1), 25–33

    Butteworth,  Nieman, Butler, and Herring, 1994, Food Intake Patterns of Marathon Runners International Journal of Sport Nutrition, 4, 1-7 Meal Composition And Iron Status of Experienced Male and Female Distance Runners,

    Cramer, JT, Housh, TJ, Johnson, GO, Coburn, JW, and Stout, 2012, JR. Effects of a carbohydrate, protein, and ribose containing repletion drink during 8 weeks of endurance training on aerobic capacity, endurance performance, and body com- position. J Strength Cond Res 26(8): 2234–2242, 2012

    Hansen, Emanuelsen, Gertsen, and Sørensen 2014, Improved Marathon Performance by In-Race Nutritional Strategy Intervention International Journal of Sport Nutrition and Exercise Metabolism, 24, 645 -655

    Shirreffs, S.M., & Sawka, M. (2011). Fluid and electrolyte needs for training, competition and recovery. Journal of Sports Sciences, 29, S39–S46.

    Williams, MB, Raven, PB, Fogt, DL, and Ivy, JL., 2003, Effects of recovery beverages on glycogen restoration and endurance exercise performance. J Strength Cond Res 17: 12–19.

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