Distance Running Nutrition and Hydration

Despite the absence of training distances beyond 30km, you’re feeling great as you through the half way mark. Gaining an extra wind and perhaps a false sense of confidence, you increase your speed half a step. If only that voice on your shoulder would have reminded you there’s still 21km to go. You hit the 30km mark and still you feel ok but decide to back off a little. Then at kilometer 35, BOOOOM. You feel like sleeping for a week. The tanks empty, you try to push on but like the last couple of reps in the gym, you just can’t squeeze them out. You steady to a walk, contemplating what happened. You’ve hit the metaphorical runners “wall”

Performing at your best is a combination of both training and nutrition. The absence of either will effect you’re end result. The “wall” as referred to by runners is one of the effects of both a lack of training and poor nutritional choices. The wall thought to be a result of falling muscle or liver glycogen levels, these falling glucose stores inevitably lead to a drop in exercise intensity and if pushed far enough, you’ll reach the wall. Both miles in your legs and a correct race day eating plan will help prevent this foreseeable event

Other than the wall, poor nutrition and poor hydration can lead to a series of detrimental events including stomach and muscle cramps, stiches, headaches and lethargy. Making the right choices with your nutrition and hydration both pre and during the race can help prevent you spoiling weeks of hard work and preparation.

In training diet and Nutrition

Much of the nutritional advice given to distance runners revolves around carbohydrate consumption both pre and during the race. Carbohydrates are the primary fuel for higher intensity activity whilst fat can be burnt during lower intensity activity. Research supports that lower carbohydrate diets result in a decline in sprint recovery performance such as sports and performance in events in the 2-10 minute range (Havemann et al, 2006, Horswill et al, 1990, Langfort et al, 1997). This is expected as the energy for these activities is supplied primarily from the glycolytic or carbohydrate pathways. When looking at longer distance events of above 60 minutes and up to many hours the water becomes a little greyer but carbohydrates do seem to still appear the winner. Fasting has been shown to reduce glycogen levels and decrease resultant work outputs (Niemen et al, 1987, Zinker et al, 1990 ). This though isn’t overly helpful as fasting will obviously decrease the body’s energy supply. A more relevant question is what happens when equal calorie higher fat and higher carbohydrate foods are compared.

Acten et al, 2004 found during moderate to heavy training there was a decline in performance of 8% when diets of 41% carbohydrates where compared to 65% carbohydrates. These diets were equal in calories and a cross over design using the same subjects

Brewer et al, 1988 performed to maximal tests over 3 days and found at 20% improvement when high carbohydrate diets of equal calories were compared to a normal carbohydrate diet

O’Keeffe et al, 1989, Compared with equal calorie diets consumed for 1 week containing 13%, 54% and 72% carbohydrates on maximal riding time. Low carbohydrate, 13% diets resulted in fatigue in 60 minutes, medium carbohydrates 54% reached 94 minutes and high carbohydrates 72 % reached 113 minutes. This study by O’Keeffe highlights the sharp declines experience in lower carbohydrate diets. Bergstrom et al, 1967 found similarly large differences of 59 mins (low), 126 mins (med) and 189 mins (high) for time to fatigue after first depleting glycogen and then feeding low, medium and high carbohydrate diets. Most of these above studies are shorter term and many people claim adaptions to higher fat or carbohydrates take time

Hedge et al 1996, performed a 7 week study on people beginning an endurance program. In this study he found the same decline when he compared diets of 65% carbohydrates to 23% carbohydrate diets over 7 weeks. Time to exhaustion improved by 67 minutes in the high carb group and only 30 minutes in the high fat, when carbohydrates were supplied there was a further increase in endurance time by 12 minutes in the high fat group, this still fell short of the high carbohydrate training group. All this research supports the fact that reduced carbohydrate consumption in training and prior to the performance assessment decreases time to fatigue in endurance activities

There have been no long term studies to confute this study by Hedge, and with most runners advocating the importance of carbohydrates in their own training we could assume this research is most likely reliable.

Recommended levels of carbohydrates consumption for runners are between 55-70% of your daily energy intake, this will vary depending on training loads with higher training loads requiring higher percentage intakes of carbohydrates.

Pre Race Nutrition

Carbohydrate loading

Pre race nutrition refers to the 2 days leading up to the race. Carbohydrate loading in most studies has been shown to increase performance marginally, Rauch et al, 1995 found carbohydrate loading increased glycogen levels by an average 47%. This translated to an increase in power output in a prolonged endurance assessment by 6%. It has been suggested that carbohydrate contents up to10g/kg per day produce increases in glycogen level but this amount will vary based on the desired running distance and training status. Tarnopolsky et al, 2001 found that a 4 day a diet of 730 grams of carbohydrate per day produced greater glycogen gains then a 4 diet of 550 grams of carbohydrates per day suggesting there are still benefits in carbohydrate loads up to 10grams/kilogram. Roedde et al, 1986 found endurance cyclists had a 22% greater glycogen storage capacity then untrained counter parts, supporting the notion training increases glycogen storage capacity. Recommendations for carbohydrate consumption pre race are included in the table

Maximum glycogen repletion rates suggest one day is required to restore glycogen levels, whilst loading may require 2-3 days if glycogen levels were initially depleted. For this reason ensure for the 2-3 days leading up to the race you considerably reduce your training volume and intensity in what is known as a taper. As heavy training will only deplete the glycogen stores you are trying to promote. Proceeding this taper increase your carbohydrate load for the final day, for ultra distances you may increase intake for 2-3 days

A simplified method rather than counting grams of carbohydrates is to increase your intake of carbohydrate rich foods to ensure you’re eating a 60-70% carbohydrate diet. Then ensure for the day leading up to the race you’re never hungry and instead you feel as though you have slightly over eaten after each meal.

Fat Cycling – Train high race low

For distances below the half marathon at light taper and increasing your carbohydrate consumption will adequately raise your glycogen stores and see you through the race. Interestingly some recent studies have suggested a possible benefit of what I will term fat cycling and endurance performance. As mentioned higher fat eating in the long term only decreases performance by lowering sustainable power output and reducing time to fatigue. It has been suggested training under glycogen depletion may produce fast fat burning adaptions. These adaptions are similar to what you would gain out of performing your long run. Studies by Burke et al, 2000, Carey et al, 2001, Lambert et al, 1994 and Rowlands et al, 2002 suggest a performance benefit from short term fat loading. These studies include period of 6 days of high fat eating, followed by one day of carbohydrate loading, in race carbohydrate drinks are also supplied. It’s thought both the increased fat burning due to the adjustment to the high fat diet results in carbohydrate sparing. This strategy can only be used short term as a constant low carbohydrate load will reduce training intensity and fitness will eventually decline. This is the same as seen with altitude training, in that short periods of high altitude training produce benefits whilst long periods result in detraining, hence the introduction of sleeping altitude simulators to allow athletes to train at sea level conditions whilst sleeping at high altitude. There also have been a few studies (not included) that produce a negative or no benefit from fat cycling

For the ultra-runners and riders out there this training method may be able to stimulate fat burning and enzyme adaptions at shorter training volumes perhaps helping to increase stamina whilst decreasing injury risk. Research is young and I’d suggest avoiding the 5-6 days of high fat eating pre-race as the side effects of such a diet switch may well cause negative consequences for your race. If you are to attempt the switch during training the period must be short and be followed by a carbohydrate loading phase.

Race day nutrition

Pre Race Breakfast

Consuming carbohydrates on the morning of the race is beneficial. A steady complex carbohydrate breakfast helps to prevent glycogen and glucose levels from falling during the race. Low Glycemic Index foods are ok if consumed 3-4 hours pre race, but if your race is in the morning like most it’s unlikely awaking at 3am to knock off a bowl of pasta is going to help your performance. Instead have an extra 2 hours sleep and have some medium GI carbohydrates 1-2 hours pre race. This means choosing some carbohydrates without too much fibre and added protein. Be careful to avoid too much fat as well. Fat, fibre and protein are difficult to digest and if you’re already on the nervous side your stomach won’t tolerate these foods. Try toast with jam, a wheat based cereal with a small amount of milk or some fruit and a little yogurt. Avoid foods such as eggs, meats, beans and high protein meal substitutes and definitely no nuts, these little guys are some of the slowest digesting foods around. Consuming .5-1gram of carbohydrates per kilo of body weight per hour is adequate and tolerable to the digestive system. The amount you consume will depend slightly on the distance of the event. This means an 80kg person would consume 40-60 grams of carbohydrates when eating one hour prior to the event or 80-120 when eating 2 hours before. See beside table

In race Nutrition

The most important race day strategy for endurance events is the supply of carbohydrates during the event. Performance benefits have been found in events of 1.5 hours and above when consuming carbohydrates at a rate of 30-60grams per hour (Wilber et al, 1992, Tsintzas et al, 1993, Millard-Stafford et al, 1992, Tsintzas et al, 1996)

A relevant question is whether these benefits are a result of carbohydrate consumption and availability or can increasing fat intake in race also improve performance. Van Zyl et al, 1996, and Jeukendrup et al, 1998, showed fats in the form of Medium Chain Triglycerides (MCT’s) had a negative effect on endurance performance when compared to carbohydrates during exercise.

Provided you‘re rested and have consumed carbohydrates in the days leading into the event your glycogen stores are adequate for a 1.5 hour event. Recommendations though are to introduce carbohydrate for events lasting above 1 hour, this will prevent blood glucose and energy levels falling late in the race. If you’ve skipped either your pre-race meal, carbohydrate loading or taper then taking in carbohydrates periodically from the 20 minute mark is beneficial. Consume 30-60g/hour of carbohydrates for medium distance events and up to 90g/ hour for longer events. Fitness and body size will affect your requirements with fitter athletes burning fuel at rates double that of their less fit counter parts. Research suggests that carbohydrates can be used from external pure glucose at a rates of up to 70grams per hour. Combining fructose and glucose allow for digestion rates of up to 100grams per hour (Jentjens et al, 2004, Wallis et al, 2005). The tolerable amount will vary from person to person. This absorption rate will provide 1100-1700kj’s per hour whilst energy expenditure could be in the vicinity of 3000-5000kj’s. 

50 grams of carbohydrates equates to 2 banana’s or 2-3 cups of sports drink. Therefor consuming the equivalent of 3 banana’s or 3-5 cups of sports drink an hour equates to the tolerable amount

In Race Hydration

Sweat Rates can vary between 250mls and 2.5Litres per hour. Sweat Rate are increased in trained athletes, in humid and hot conditions, in acclimatized athletes, in faster athletes and in men compared to women Weighing yourself pre and post training run is a helpful way to learn your sweat rates in hot and colder conditions.

For high intensity exercise up to an 1hour water is a suitable source of hydration unless you ‘re in search of additional glucose. For distances beyond an hour and ultra-distance events including and above the marathon it is important to consider your carbohydrate and electrolyte balance. Hyponatremia is a dangerous occurrence where by sodium levels fall to below 135 mmols/l. The consequences of this can be life threatening. Hyponatremia is quite common in distance events, in the Boston Marathon 62 runners of 488 had hyponatremia and 3 runners had critical levels (Almond et al, 2005). The closer the runners fluid intakes were to their sweat rates and the slower the runner the more likely is was for hyponatremia to occur. In extreme circumstances of over hydrating during running this can be fatal. Don’t fear though, this won’t happen provided you make rational decisions. It’s important that in events of 30 minutes to 3 hours hours that your fluid intakes are slightly below your sweat rates.  Noakes 2005, calculated that complete glycogen utilization can provide close to 2 Litres of water. He suggested it is theoretically possible for an athlete to have a 2-3% reduction in body weight post event and still remain adequately hydrated. Using this knowledge you can safely consume 500-750mls less than your sweat rates for distances under 1.5 hours. If you’re a lower level athlete don’t drink 3 litres per hour on a 15 degree day as your sweat rates will unlikely be this high also don’t attempt to hyper hydrate pre race by drinking excess water. On events of 3 hrs or more it’s important to hydrate with drinks that include electrolytes namely sodium. Sports drinks have these electrolytes added making them preferable choices in ultra-distance events. If you’re not consuming sports drinks you may require a slice of cheese or another salty snack and a banana every hour as part of your nutritional strategy. Provided you stick with these basic strategies your risk of hyponatremia is greatly reduced

References

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