Ask the Experts: Ruth McKean on Half-Marathon Nutrition



ruth mckean nutrition

Sports dietician and ASICS PRO Team member Ruth McKean is a leading sports dietician and an advisor to the Scottish Institute of Sport. She is also a member of the British Dietetic Association and Health Professional Council, and a former Scottish National 5,000m champion.

She joined us last Friday to answer your nutrition questions and help you to develop a race fuelling strategy  as your autumn half-marathon gets closer.

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Read the whole forum debate

Q: I'm currently using low GI foods to fuel my runs and have been experimenting with flapjacks. Do you have any recipe advice or other ideas for low GI foods that I can eat on the run? Emmy_bug

A: Low GI (glycaemic index) foods can be useful to both runners and non-runners since they are thought to help with blood glucose control. The index is used to rank foods according to the immediate effect on blood glucose. White bread, for example, is a very high GI food. High GI foods are classed as ones that are broken down quickly and therefore glucose enters the blood rapidly whereas low GI ones release sugar more slowly and stop a rapid increase in GI.

However, if you eat large portions of a low GI food it will still raise your blood sugar levels as the glycaemia load is also important. So you must also control portions and it may be better to eat smaller meals then some snacks and also bear in mind if you train twice per day then a higher GI recovery snack may be a good idea.

A low GI breakfast and low GI lunch appear to create a helpful effect for the rest of the day, so focus on these meals. Low GI food at breakfast could be porridge oats, granary/seed-rich bread with peanut butter or other nut spreads such as almond or cashew spread, or a pot of yoghurt.

Other low GI foods include apples, unripe bananas, pears, mangoes, grapes, baked beans, untoasted muesli, crumpets, pasta, milk, low-fat fruit yoghurt. Blood glucose control is usually better when a consistent eating pattern is adopted with regular meals and snacks.

Also when you add fat and protein to a meal this can change the GI of a food. So if you have a jacket potato, for example (which is very good for you but is also a high GI food), with tuna, cottage cheese or beans, the combination will change from a high GI food to a lower GI food.

The flapjacks are a good idea but they can be calorie dense due to the butter, nuts, honey/syrup, so while they may be low GI, don’t eat too many too often. Try to use recipes that include fruit, nuts or seeds that you don’t usually eat as that increase the range of vitamins and minerals in your diet. And us as little butter and sugar as you can get away with. I tend to adapt recipes’ and just see how they turn out but I look out for lower fat version. The internet has loads of ideas on this.

Q: Despite being fully hydrated, with the right balance of salt etc, I still am prone to calf cramp in the latter stages of a marathon and even a half. Is there anything I can add or remove from my diet to help? ghost of kittenkat

A: Exercise associated muscle cramps (cramps that only occur during exercise) most commonly occur in the calf for runner and can range from a twinge to stabbing pain. The cramp occurs when the muscle involuntary contracts and does not relax. It is thought this is due to unusual stimulation of the muscle but really the exact cause is unknown.

However, cramp occurs more often in tired muscles so if you’re experiencing cramp in races, it could be that your muscles are struggling to cope at this stage of the race so you might need to change your training. For example, at end of a very long run when your muscles are tired, put in some race pace efforts. If you have a coach, speak to them about this.

I don’t think your cramp is related to your nutrition strategy. Hydration (or rather dehydration) has been suggested as a possible cause of cramp but the evidence is not strong to support this. You may have also heard that cramp is linked to the loss of potassium, calcium and magnesium but again there is little support for this theory as we only lose tiny amounts of each when we sweat.

If you do not fuel well before racing, that might also increase the chance that you get cramp as under fuelling means that muscles fatigue earlier than they might usually. Make sure you eat as if you are still training hard for the last two days before the race and if you take more than 90 minutes to complete the race, it’s probably worth taking on some fuel and fluid along the way.  

Some suggestions to reduce risk of cramp are as follows:
Stronger and fitter muscles are more resilient to fatigue and cramp so work on strength and fitness. Be careful when changing speed and/or intensity, particularly during the latter stages of a race, as fatigued muscles take longer to adapt to increased intensity.

Wear comfortable, unrestrictive clothing and footwear. Practice good hydration both before and during exercise. You could also try using an electrolyte drink like Nuun, High Five Zero or SIS Super Hydro the morning before the race.  

Q: I'm a complete beginner when it comes fuelling for longer runs. Do I go for simple carbs or complex ones? Do I need energy gels or sports drinks? I'm confused! sarah marsbar

A: My advice is always to keep it simple. On long runs, your body is interested in the sugars in simple carbs – you have enough fat and protein in reserve (although no matter how well fueled you are you will still use some fat and protein but primarily carbs).

This message has not changed in sports nutrition but you may read about fats and protein forming some of the foods in distances above the marathon but for distances under this, simple sugars and drinking to thirst are the key messages. However you should aim to get away with as little sugar as you need without compromising performance as too much may cause stitches, stomach discomfort and feeling sick. Consume too little and you’ll run out of energy.

If you are running for up to an hour, you don’t really need any fluid or fuel unless you start dehydrated or it’s particularly hot. If you run steadily for an hour to 90 minutes I would still suggest no fluid or food but if you’re running for more than 90 minutes, carry both fluid and fuel.

Start with 20g of carbs per hour, so this would be around 330ml of an isotonic sports drink or fresh orange juice diluted 50-50 with water by half (so 50 per cent water, 50 per cent fruit juice), but often water is enough and you may struggle to drink 330ml in an hour. You could also have a jelly baby every 15 minutes or a gel after 45 minutes (these usually contain around 25gmof carbs).

People will have different levels of stomach comfort with different foods and need different amount of carbs per hour but I suggest you experiment to find a balance around the 20-40g mark. Some runners need as much as 50g per hour but only a few will need more than that. A race is always going to have bad patches but nutrition can help.

Q: Do you have any advice for older runners? I'm interested in antioxidant-rich foods that might help me to recover and avoid injury. Aches and pains don't go away as quickly as they used to. Hilary Francis

A: This is a good question. Antioxidants are an interesting area. They are found naturally in brightly colored fruit and veg (berries, oranges, peppers etc) as well as teas and some other foods so first I would suggest you have at least five different brightly coloured fruit and veg in your daily diet.

You could try Cherry Active (a concentrated form of cherry juice). There is both anecdotal evidence and objective evidence that this may reduce muscle soreness due to the anti-inflammatory effects of the antioxidants. If you do decide to try Cherry Active, don’t consume any further antioxidant supplements, other than those that occur naturally in foods, as there is some evidence to suggest that too many antioxidants through supplements can cause stress to your body.

Q: I have torn my calf muscle and was wondering if there are any foods that will help me to heal faster? I only have five weeks until the Great North Run. Mike Rutland

A: No! Do exactly what your physio has told you to do to recover. At this point, there’s no evidence that one particular food will help you to recover faster but a healthy diet with a good range of vitamins and minerals might help. Best of luck; I really hope you have a speedy recovery.

Q: If I get up at silly o'clock to run I tend to stretch, drink a pint of water then go. I have run up to 13 miles without having anything to eat. I am normally famished when I get back. Am I doing myself any harm, or increasing the risk of injury, or is this a good way to teach my body how to run on my fat reserves? Skinny Fetish Fan

A: There is a lot of interest at the moment in training in a fasted state. The theory is that it could encourage physiologic adaptations which help your running (and part of that is using more fat).

Doing 13 miles before breakfast is fine if it is a steady run but if you are running an intense session and the pace drops for the last few miles then you may be losing out. However, it depends how you run throughout the week. If you run before breakfast once or twice a week I think there could be some benefit to this. If you’re doing every run before breakfast though, this may be useful but you need to consider if  you feel knackered for the rest of the day because recovery will be longer, you will feel more tired and your immunity may be compromised, which could lead to injury as running when tired stresses muscles.  

So to sum up: adopt your strategy of running before breakfast for a couple of runs a week but also do some quality well fuelled runs, because if you are not putting in the pace due to a lack of fuel then quality of a session decreases and this shows when you race. And if you are very lean, you could be breaking down protein, which might lead to you losing some strength in certain aspects of your running.

Q: I'm running the Bacchus Half-Marathon in September. The organisers provide a range of fuel along the course, including water, wine, Jelly Babies, gels, bananas, oranges, biscuits, dried fruit and crisps. What would you recommend going for?  What kind of impact would a glass (plastic cup) of wine during the race have on me? Emily Grainger

A: Stick to the sweets and gels! No wine and even fruit may not agree with you. During a half, people often don’t eat or drink anything if running under 90 minutes. If you are using food (gels, sweets) you must practice this and even drinking out of plastic cups if that is what they will be handing out. Good luck and have the wine after you have hydrated and eaten something post race.

Q: I'm training for the Stroud Half-Marathon in October. I'm aiming for a time around 1:35 and am looking at nutrition to try to help me rediscover some form. I've cut chocolate from my diet (replacing it with fruit) and reduced alcohol to almost zero. Will this strategy help bring my times down (on top of training of course) or won't it really make much difference? I weigh around 10.5 stone, so luckily losing weight isn't an issue for me. Tempo Tom

A: Thanks for this email but I really don’t have enough information to help. Is your training right? Are you eating enough to recover over a 24-hour period? Are you getting sufficient sleep? If you can become leaner without injury risk and compromising on getting what you need from your diet you may well run faster. You don’t need to give up alcohol entirely, although it could be a good thing to cut it out  just before the half. It would be interesting if you could get a good coach to look at your training as well.

Q: Towards the end of a half or full marathon, I tend to completely tank (especially in a full marathon). I get to a point in a race where I can't keep any carbs down. I usually manage two to three gels but then can't stomach any more. I've done cross-country ultra-marathons when I'm doing more walking/jogging and have managed to eat protein (especially boiled eggs) and that works but obviously I can't do that on the run. Are there any protein shots available or something you'd suggest to get me to the end? Melissa Butcher

A: Are you eating soon enough and are you starting sufficiently hydrated? If you have little fluid in your stomach, digestion becomes harder and if you wait to eat until too late this also can cause problems. Have you tried a gel shot (do you mean like a Clif Shot Blok jelly cube?) or you could have one sweet every 15 minutes, starting 15 minutes into the race, then at 30 minutes, 45 minutes etc. I don't think protein will help in distances less than 26 miles. I think little and often may work for you and a very planned approach and sip little and often on some water and start well hydrated.

Q: I'd like some advice on how to fuel my half/marathon training. I'm finding it really hard to keep up with the calorie deficit running creates. Also should I be completely cutting out junk and processed food in order to improve my running or will it not make a difference? Anna Williams 13

A: This is actually a hard question to answer because if you are not getting the calories you need then your running will suffer but if you eat too much processed food, which is often high in fat, or even too much protein, this could displace where the carbs should be going and you’ll fatigue earlier.

Have you tried specific recovery strategies like a 500ml fruit milkshake post run? This contains around 350 calories but also lots of carbs, protein and calcium. Then eat again in two hours and then again in another two hours so you are eating three meals and three to four snacks per day.

Useful snacks include a snack-size pasta pot (left over form night before), high-calorie cereal such as museli with nuts and dried fruit (nuts have lots of calories and dried fruit more calories than fresh. Organise your food and eat little and often and this should help.

You may also get away with some dark chocolate each day, don't be afraid of this but look at you diet as a whole and make sure you eat lots of good foods: fatty oily fish twice a week, small amounts of oil in cooking, eating often and aiming for some carbs in all meals and snacks.

Q: I am currently training for the Budapest Marathon in October. I am in the process of building up my long runs and therefore need to think about fuelling during my runs. I am all for going ‘natural’ so my questions are: Do you have a recipe for a homemade sports drink that will keep me going during long runs? And what are the best natural snacks during a long run? Timi

A: Fruit juice such as orange juice diluted 50:50 with water will give you an isotonic sports drink. If you think you need salt (and you may not) then a pinch add a pinch to the drink. Depending on your stomach, you could make your own sports bars or use products like Clif Bars as they have a natural approach.

Q: Are there any running 'super foods' that you would recommend introducing to a runner's diet? I'm currently training for the Great North Run. MDZ

A: There is no one super food or foods that I would recommend, rather it is  a combination of a varied diet and the training and lifestyle factors that will make the real different. There are vast numbers of products that promise to do this, but the most popular current one is beet juice/shots as there is some evidence this helps the non-elite runner.

Q: What’s the best thing to eat after a long run, and when should I consume it? mike gregory 7

A: Eating as soon as possible after a run (and definitely within one hour) is vital if you’re training twice a day. You have a little more time when you’re training daily or every other day but it is good t get into the habit of eating immediately because if you do not eat after a long run you can become very hungry and over eat later and be more tired for the rest of the day.

Great recovery foods contain a combination of carbs and protein so try things like cereal and milk, milk-based drinks such as milkshakes and yoghurt drink, a lean meat/fish sandwich with fruit or fruit juice, and pasta or rice with some lean meat or fish. The best protein comes from an animal source (unless you do not eat meat/fish/dairy). You should aim for around 50g of carbs, or more if you struggle to keep weight on and less if need to lose some weight. You only need 0.8g of carbs per kilogram of your body weight and some protein if want to reduce the carbs.

Q: I’m currently trying a low-carb diet as I’m trying to shift some weight before my next half marathon in an attempt to improve my time. Obviously I need carbs for long runs but what would you say are the top three sources of good carbs that might also help me continue the weight loss? Also is mackerel good for me? I've been eating more of it but I’m worried that it’s very high in fat. Jonathan Meadows 2

A: I would need to see a little more of your diet to give you the best possible advice but you could base your meals on oats, wholegrain pasta or rice and sweet potatoes, while exercising portion control.

Mackerel should stay in your diet: have a a couple of 125g portions per week. Check out this link for useful information: http://www.bda.uk.com/foodfacts/omega3.pdf

Q: Sports drinks and protein drinks have been in the news recently as to their effectiveness and whether average people actually gain any help or advantage from using them. I wondered what your take on them was. Adam Haylett

A: I don't think anyone needs them but in marathons etc they can be very useful as they’re compact and readily available. I totally agree with the recent news that kids and people who just exercise for a gentle hour do not need them nor gain anything from them. But kids also do not need cola and other sugary drinks so I think used in the correct situation they can be useful.

Q: Which breakfast cereal or food do you think would be best for early morning runs, when I don't feel like eating at all, so only want the minimum volume-wise.  I can't do porridge, as it makes me want to wee all morningGeraldine Williams

A: For something light and easy a slice of plain toast or bread (no seeds etc) and some jam and honey or a small pot of natural yoghurt with a little honey and a very ripe banana or some fresh orange juice (dilute with water if wish) but if you're running for less than 45 minutes I would just get and up and go with a glass of water before you go. Cereal is a great recovery snack after as it has both a good source of carbs and protein.

Q: I'm reasonably new to long-distance running and am currently working towards a half-marathon in October. I'm hoping to run a full marathon after that. So far the furthest I've run is 11 miles. I find I often start to get stomach cramps around 10K, sometimes they remain in the background and I keep running the full distance, sometimes they get really bad and I have to walk or even stop. I've tailored what and when I eat on the days of my long run - usually a bagel with jam and fruit in the morning, pasta at lunch, I avoid dairy altogether, and stop eating altogether at 2.30pm for a 7pm run - and while it's helped a bit, I do still get them. Do you have any other thoughts on how I can stop this from happening? Especially as I'm trying to build up my distances... smdj

A: You are doing everything I would suggest although you do not mentioned fluid: do you have any sugary fluid before runs (sports drink, fruit juice etc)? If you do, I would try just having water. The cause of stitches is still debated but most recent thought is that the two layers of membrane inside the tummy wall can become irritated so not eating too closely, avoiding sugary drinks like milk, and the above can help as well as cutting down on fat and fibre as these can distend the tummy. Could your running style change when you get fatigued and somehow cause this? I am just suggesting this as I don’t know. Most people just need to change food and timing and this becomes a rare thing. If the pain was to continue after running stop then I would see your GP.


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Posted: 16/02/2013 at 16:18

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Posted: 22/04/2013 at 15:56

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