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Runner's World (UK) - - Carbs Fuel For Running -

EN­ERGY BARS These are solid, so take longer to be ab­sorbed into the blood­stream. This may be a dis­ad­van­tage in shorter races, but can work in your favour over longer dis­tances. They’re also good be­fore a long race. Some peo­ple find bars more palat­able than gels.

SWEETS Any­thing with a high sugar con­tent will help re­stock your body’s glyco­gen stores quickly, although you won’t get ex­tra ingredients like elec­trolytes. Sports nutri­tion sweets are also avail­able.

MALTODEXTRIN This is of­ten the pri­mary car­bo­hy­drate source in gels and en­ergy drinks. It’s de­rived from corn­starch, easy to digest and de­liv­ers en­ergy quickly.

GLU­COSE The most com­mon carb in na­ture, also of­ten known as dex­trose.

FRUC­TOSE De­rived from fruit sugar, and ab­sorbed via a dif­fer­ent pathway to glu­cose, so when taken in com­bi­na­tion it can in­crease your body’s max­i­mum car­bo­hy­drate­ab­sorp­tion rate.

SU­CROSE Glu­cose and fruc­tose com­bined. Oth­er­wise known as ta­ble sugar. SODIUM A key elec­trolyte. ELEC­TROLYTES Im­por­tant body salts and min­er­als, which are lost via sweat. For more in­for­ma­tion, see the hy­dra­tion sec­tion, p26.

CAF­FEINE A stim­u­lant that has been proven to boost per­for­mance and lower per­ceived ex­er­tion. Re­search shows you need 3mg per kg of body weight, but con­sider the tim­ing of your caf­feine hit, as it only reaches peak ef­fect an hour af­ter con­sump­tion. Try it in train­ing so you know how it af­fects you.

● SIS GO En­ergy + Dou­ble Caf­feine gel (150mg per gel), £11 for 6, sci­en­cein­sport.com

● Mypro­tein En­ergy Elite + Caf­feine gel (75mg per gel), £17.99 for 20, mypro­tein.com

● Max­in­u­tri­tion Fuel­max Plus gel (100mg per gel), £40.99 for 24, shop. max­in­u­tri­tion.com

NITRATES Nat­u­rally oc­cur­ring in some veg­eta­bles, (beet­root is a par­tic­u­larly rich source), ni­trate is con­verted into ni­tric ox­ide in the body, which in­creases blood flow and oxy­gen de­liv­ery. Ex­eter Univer­sity re­search found that drink­ing 500ml of beet­root juice a day for six days in­creased time to ex­haus­tion by 15 per cent. Also, ‘acute doses’ taken just be­fore ex­er­cise have been shown to boost per­for­mance. In one study, 6.6mmol (the amount of ni­trate in a Beet It Sport Shot, see be­low) taken be­tween two and two and a half hours be­fore ex­er­cise im­proved per­for­mance by 2.8 per cent.

WHAT KEY INGREDIENTS SHOULD I LOOK FOR WHEN I’M CHOOS­ING CAR­BO­HY­DRATE PROD­UCTS?

HOW MUCH WA­TER DO I NEED TO DRINK WHEN I’M RUN­NING?

The best ad­vice is to drink ac­cord­ing to your thirst – it’s a strong pre­dic­tor of your hy­dra­tion needs. ‘Our thirst mech­a­nism is pretty ac­cu­rate,’ says Su­san Year­gin, as­sis­tant pro­fes­sor of phys­i­cal ed­u­ca­tion at the Univer­sity of South Carolina, US. In fact, drink­ing too much wa­ter can lead to a con­di­tion called hy­pona­traemia, in which salt lev­els in the blood be­come dan­ger­ously low, with symp­toms that range from headaches and nau­sea to seizures, coma and, in ex­treme cases, death. A sim­ple way to find out your hy­dra­tion sta­tus is to check the colour of your urine. If it’s clear or pale yel­low, you’re well hy­drated. But if it’s the colour of ap­ple juice or darker, you need to drink up. For runs shorter than an hour you can go with­out wa­ter, pro­vided you’re well hy­drated at the start. Dur­ing longer runs the op­tions are to wear a hy­dra­tion pack (a back­pack con­tain­ing a wa­ter blad­der and mouth­piece), or plot a route that passes your home or other point where you have stashed wa­ter. You could also try long runs with iso­tonic en­ergy gels (which pro­vide a lit­tle hy­dra­tion, as they con­tain wa­ter) but with­out wa­ter it­self – if try­ing this, build dis­tance/du­ra­tion grad­u­ally to al­low your body to get used to them. Dur­ing half- marathon races and longer, drink­ing lit­tle and of­ten (a few mouth­fuls at each aid sta­tion), rather than gulp­ing down lots in one go, will be eas­ier on your stom­ach.

SHOULD I AIM TO RE­PLACE THE AMOUNT OF FLU­IDS I’VE LOST AF­TER A RUN?

If you sweated a great deal, re­plen­ish­ment of flu­ids is im­por­tant, but, again, you can judge how much you should drink sim­ply by thirst. If you want to be more pre­cise, there’s a fairly easy way to work out your needs, says Dr Chris Eas­ton, lec­turer in ex­er­cise phys­i­ol­ogy at the Univer­sity of the West of Scot­land. ‘ Weigh your­self be­fore go­ing on a 60-minute run. Don’t drink any­thing while you’re out and towel off any ex­cess sweat when you get back; then weigh your­self again. Each gram in weight you’ve lost equates to 1ml of fluid, so that fig­ure is how much fluid you need to re­place for ev­ery hour of train­ing.’ So, if you lost 1kg of weight, your sweat rate is one litre per hour and you could aim to re­place at least this amount over the course of the rest of the day.

WHAT ARE ELEC­TROLYTES, AND HOW IM­POR­TANT ARE THEY TO A RUN­NER?

Elec­trolytes are salts and min­er­als that con­trol the fluid balance of the body, and they play a key role in mus­cle con­trac­tion and en­ergy gen­er­a­tion. Sodium, potas­sium, mag­ne­sium and cal­cium are among the ma­jor elec­trolytes. They’re lost through sweat, so it’s good idea to re­place them af­ter a hard work­out, es­pe­cially if you’re a salty sweater (look for white marks on your kit or even your skin af­ter a run). Some sports drinks con­tain elec­trolytes, and you can also buy tablets that add flavour and elec­trolytes to wa­ter with vir­tu­ally no calo­ries or carbs.

WILL DRINK­ING TEA AND COF­FEE DEHYDRATE ME?

While caf­feine pro­vides a proven per­for­mance- boost­ing edge, it also acts as a di­uretic, right? Well, not ex­actly. ‘Re­cent re­search shows that caf­feine doses be­tween 250 and 300 mil­ligrams – the equiv­a­lent of about two cups of cof­fee – will min­i­mally in­crease urine out­put for about three hours af­ter con­sum­ing it,’ says Year­gin. ‘How­ever, the re­search also shows that ex­er­cise seems to negate those ef­fects.’ So, ul­ti­mately, you can con­sider tea and cof­fee (and other liq­uids such as fruit juice) as con­tribut­ing to your daily fluid in­take. Just be sure you get your caf­feine hit at the right time

When it comes to hy­dra­tion, lis­ten to your body: it knows what it needs.

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