Green vegetables can make you go faster and for longer - really!

Fresh greens from Dad’s garden!

‘Eat Your Greens’. You have no doubt heard this one before!  From a parent, a grandparent, or maybe from a dietitian.  If you’ve heard it from a sports dietitian lately it is with good reason – eating enough of the right type of vegetables, particularly green and leafy varieties, can help you go faster, and/or for longer.  Pretty handy for many athletic pursuits – whether you are elite performer or working on your personal PB.  Here’s how it works. 

Why green veg?

Yes, green vegetables are great for vitamins, minerals, antioxidants, fibre, etc.  But green leafy vegetables like spinach, lettuce, rocket (arugula) and kale also contain nitrate – so does beetroot.

How does it work?

Nitrate from food has a remarkably clever role in the body.  It is converted to nitrite by bacteria in the mouth, which is then converted to nitric oxide in the stomach.  Nitric oxide acts as a neurotransmmitter for a range of body systems and can have a number of positive effects on the body. Studies show that dietary nitrate, at doses that are commonly found in vegetable-rich diets, exerts beneficial effects on cardiovascular health via effects from nitric oxide.  It’s likely that nitric oxide (and potentially other nitrogen compounds), are responsible for the impact on sports performance.

The main benefit of nitrate appears to be a reduction in the oxygen demand and energy cost of exercise, thereby improving efficiency at submaximal workloads.  An improvement in exercise efficiency theoretically allows an individual to exercise at a greater intensity for the same level of effort OR sustain the same level of performance for a longer period of time (delayed onset of fatigue).

Who is it good for?

Up until recently, nitrate was considered of most benefit to endurance athletes due to the impact on oxygen use, however more recent research indicates a positive impact on muscle force development –  which translates to potential benefits for strength, speed and power athletes, as well as intermittent team sport performance.

A number of studies, including those by Larsen et al (2007) and Bailey et al. (2009) have found that sodium nitrate consumption, in an amount achievable with regular green vegetable intake, resulted in reduced oxygen use during submaximal exercise, coupled with an improvement in cycling time to exhaustion. When it comes to performance, Lansley and colleagues (2011) reported an improvement of ~3% to 4km and 16km cycling time trials respectively, in trained individuals following an acute dose of beetroot juice consumed in the hours before exercise.

As a lot of my work is with team sports, a study on football (soccer) players in 2016 by Thompson et al also attracted my interest, with 5 days of beetroot juice supplementation prior to a YoYo test showing an increase in distance covered.

How much, when and how?

Athletes commonly take nitrate via a concentrated beetroot juice shot, taken either in a regular daily dose and/or in the hours prior to exercise.

The standard dose is ~ 5-6 mmol (or ~300 mg) nitrate, provided by one beetroot shot.  However there may be benefits of a higher dose, and some individuals may need more to see an effect.  Those with a higher fitness level (>65ml/kg/minVO2 max)  may also have less of a response.

Care should be taken however not to over-consume, and supplements are not recommended for this reason.

It takes around 2 hours for nitrate from food to be converted and delivered to key areas for a performance impact.  Some athletes take nitrate prior to an exercise session, however it may be more effective (and better overall nutritionally) to have a regular intake, spaced out over the day, during periods of high training loads ie. vegetables!  The standard dose from one beetroot shot is equivalent to ~250-300g nitrate-rich vegetables and regular intake may provide similar results to more acute pre-training doses.

Put it into practice

Aim for ~250g of nitrate-rich vegetables per day:

Spinach

Kale

Rocket/arugula

Lettuce

Chard

Celery

Beetroot

Cabbage

Parsley

Radish

Leek

Broccoli, carrot, cauliflower, cucumber and pumpkin are a little lower in nitrate, but the amount can add up if you are having reasonable portions.

Vegetables can vary in their nitrate content due to location and farming methods. For example, vegetables grown with nitrogen containing fertilizer will yield the greatest amounts of nitrate (therefore organically grown vegetables are likely to have lower nitrate levels).

Cooking method is also important, with boiling being the most likely cooking method to create nitrate loss. 

Any risks?

When we think ‘nitrate’ we often think preservatives.  There have been potential health risks associated with high levels of nitrate from foods, additives and water sources, however both the WHO and The European Food Safety Authority have indicated that the beneficial effects of eating vegetables and fruit as part of a balanced diet outweigh any potential risk to human health from exposure to nitrate through vegetables, and that intake up to 250- 400g mixed fruit and vegetables per day would likely not exceed ADI (acceptable dietary intake) and in fact may provide health benefits.  If you are an avid vegetable fan, you may need to be cautious, particularly with rocket (arugula) for example as it is one of the very high nitrate vegetables and excessive intake should be avoided.

Eat Your Greens

So the moral to the story is ‘Eat Your Greens’ – everyday – particularly during times of hard training.  The current research surrounding nitrate from food sources reports potential benefits for a range of sporting situations, improving skeletal muscle efficiency and having performance effects on endurance, high-intensity intermittent exercise and muscle power.

Speak with an Accredited Sports Dietitian if you would like to review your nitrate intake or if you would like more information to suit your specific needs.

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Lose the lollies - why lollies should not be seen at kids’ sport

Lollies are for parties. 

They were when I was a kid anyway.

How confectionery has become part of post-game culture at junior sporting venues has me bewildered.  Somehow, the practice of elite endurance athletes, who are known to use simple forms of sugar as fuel during prolonged training and events, has transcended to kids’ being handed a bucket full of colourful jellies as primary recovery food following a 36-minute basketball game.  Why?  Or why not should be of greater concern for parents across Australia who are effectively the gatekeepers of the regular post-game sugar fest.

How did this happen?

Jelly lollies have become popular with endurance athletes as a convenient, portable and enjoyable carbohydrate source for lengthy training sessions.  Long rides or runs, where it may be difficult to consume adequate solid foods, make lollies an easy choice for a quick energy boost.

A typical junior sporting event usually takes less than 1 hour.  I am talking typical team sports here, in particular the ones I attend on a regular basis - basketball and footy.  Every time I attend a game, at any venue, I almost always spy lollies or chocolate in some form (ok, Saturday 8am basketball perhaps less likely, but not completely unexpected…).

This concerns me……a 10 year old does not need a quick acting carbohydrate immediately before, during or after a game, especially if they have eaten well beforehand.  Yes, kids do get hungry after sport, and recovery may also be a consideration for particularly active children.  Give the child some proper food to eat.   There is absolutely no need for lollies post-game. 

Why am I so angry!

Lollies and junior sport should not be used in the same sentence and here’s why:

-        Feeding children lollies after a game creates the perception that lollies are an everyday food, or even worse teaches kids that lollies and sweet foods are a reward for effort.

-        During and after sport a child’s saliva production is reduced and teeth are vulnerable to attack (so my wonderful dentist thoughtfully reminds me) – introducing a sticky, sugary sweet is asking for trouble.  Want a massive dental bill – keep giving your kids lollies (and sports drink) every time they run around a court.

-        There are SO many better choices out there to help kids recover, feel good and fill them up after sport. 

Sure, it may just be a jelly snake here and there and you may think I am over-reacting, but kids get enough opportunities to eat lollies at other times.  Keep the lollies where they belong – in beautifully packaged little bags handed to guests as a birthday celebration thank you.  Not in the sports bag.

Hydration is important, but what is the role of sports drinks and electrolytes and who needs them?

Image courtesy of Melbourne United Basketball Club

Summer in Australia can get hot!  Daily fluid intake is essential, but how much, and what type, do you really need for optimal energy levels, performance and health?  If you train regularly you need to drink regularly, but it’s not just about drinking as much water as you can.  Working out your individual needs can help you hydrate to train and perform at your best.

Why hydrate?

When we exercise we sweat, leading to higher fluid losses and increased fluid needs.  Starting training hydrated means setting yourself up to: 

- improve concentration and judgement

- improve co-ordination

- improve energy levels and delay fatigue

- make exercise feel easier, so you feel better and can work harder

Best fluids for training

For most exercise and sport, water is the drink of choice and totally adequate.  However many active people are turning to the wide range of sports and electrolyte drinks to help power their performance.  But are all the fancy formulations worth the effort and investment? 

Sports drinks vs electrolyte drinks

The key question to ask is whether you need fuel, fluid and/or electrolyte replacement.  Commercial sports drinks generally contain both carbohydrate and electrolytes and can be useful during prolonged training, hot and humid conditions and any time that sweat rates are high and when additional fuel in an easily consumed form is required. 

If your main priority is hydration, there are a number of pill and powder options that provide electrolytes without the carbohydrate and sugars.  The main electrolyte that drives hydration is sodium, so in essence you are purchasing a high salt solution to aid in fluid absorption and retention. 

If you don't do large amounts of prolonged training, enough sodium will likely be consumed through foods, and additional electrolytes may not be required.  However if you participate in long-duration exercise or have a high sweat rate with the potential to lose significant fluid and sodium, an electrolyte supplement could be pretty useful.  Salty carbohydrate-rich snacks can be handy too for those longer pursuits as a fuel and electrolyte source – just add water!  But if the event makes eating difficult, a sports and electrolyte drink or combination might work well (worth practicing in training to see what works, but for most shorter training sessions water may be fine).  Sports drink swishing is another strategy if you want the effects but not the fuel and carbs, might need to write a post on this down the track. 

When you are not exercising, other nutritious fluids such as milk, soup, blended fruit smoothies, juice, tea and coffee all help you to hydrate.  In fact milk can have a higher electrolyte content than many sports drinks!  Coffee can have a diuretic effect, so is not as effective in helping your body to hold onto the fluid you drink, but can still contribute to hydration goals. *For more hydration info, see my previous blog post Best Fluids for Hydration - Look No Further Than Soup.

Individual fluid needs vary significantly due to a number of factors.  Work out how much you need and the best fluids for you for different scenarios, and ask an accredited sports dietitian if you need some help working it all out.

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Energy For the Mountains - Tour de France Nutrition

If you love sport, then July is possibly your favourite month of the year.  In Australia we are in the middle of our busy winter sports seasons, but we are also spoilt for choice with international events, meaning lots of late nights and bleary-eyed mornings for armchair spectators! 

I have developed an interest in the Tour de France over the years, although I must admit I haven’t seen too many live stages this time around.  As I get older the timezones don’t seem to work so well for me!  I do love watching the amazing TV coverage of this gruelling endurance feat, and being a sports dietitian I take great interest in what the cyclists eat and drink, as well as when and how.  Juggling food and fluids on two wheels is a skill in itself! 

Getting the food and fluid right on multi-stage events like the 21-day Tour de France can impact on how the athletes feel on the bike, how they recover and how they perform.  Extreme sporting events present a number of challenges, with fuelling and hydration being critical for overall success. 

I had initially planned to write a detailed piece about nutrition for the Tour de France, however over the recent two weeks I have seen plenty of great content already published on other sites.  So rather than re-writing,  I will highlight the nutrition priorities below and provide either my own thoughts or link back to other experts. 

So much food, so little time:

When you are on the bike for a fair chunk of the day, plus all of the travel, preparation and commitments, it can be difficult to find time to eat enough.  A recent post from Asker Jeukendrup, exercise physiologist and sports nutritionist,  highlighted some of the research on multi-stage cycling and predicted energy requirements. The amount of energy expended per day for the major cycling tours is estimated to average 6,000 calories.  On the big hill stages, expect up towards 9,000 calories per day.  There are a number of factors that contribute to energy expenditure and there will be wide individual variation, however these figures are a good indicator of how hard to body is working during these events.  The calorie requirement can be 2-3 times what the average male needs to eat in a day! When you consider that 5-6 hours of the 15 or so awake hours is on the bike it doesn’t leave a lot of time to consume that amount of energy.  Particularly when you think that riding up a mountain at altitude (sometimes in the wind and rain) does not make eating an easy task.

For a short but detailed read on how much energy is needed to fuel an elite professional cyclist go to Asker Jeukendrup’s blog, which also provides a visual comparison of what 9,000 calories looks like in burgers!  Can you guess how many?

Food on the bike:

As mentioned, eating while riding is a practiced skill in itself.  Different types of foods and fluids suit different individuals.  Professional teams these days have support staff including dietitians, sports scientists and chefs who help the athletes to achieve optimal performance nutrition during tours.  For more information about the carbohydrate requirements of cyclists during stage events, go to the Premax blog 'Sugar for Cycling Performance. Part 1: How Much is Enough?'.  I have recently started writing for the Premax blog as a guest nutrition contributor, excited to be involved!.

For some practical ideas for home-made snacks on the bike, The Feed Zone website is a great resource, plus they do some great recipe books about the food the pros eat that you can also do yourself at home.  I have the Feed Zone Portables book at home and it’s great.

Food off the bike:

After a day’s racing is when nutrition really needs to step up.  Recovery goals are similar to other sports, with a focus on protein, carbohydrate, electrolytes and fluid.  Elite cyclists working at such high intensities burn a lot of carbohydrate, particularly during hill stages.  Although carbohydrate and protein are essential, it’s important to also think about overall nutrition and incorporating vegetables – not just endless bowls of spaghetti bolognaise.  If you want an insight into see what professional cyclists REALLY eat, follow Orica-Greenedge’s chef Nicki Strobel on Twitter……definitely not just endless bowls of pasta!

 Hydration:

If you have been watching the Tour this year, you would have noticed that some days are raced in the heat of the day with the European sun beating down on sweat-soaked jerseys, while other days jerseys are drenched by the soaking rain, wind and cold.  Hydration is important in all conditions, but fluid losses are likely to be higher in the heat.  The big challenge for multi-stage events is that you only have overnight to recover before you do it all again, so rehydrating strategies are essential to ensure athletes are hydrated on the starting line the next morning.  Sweat means fluid loss, but also potential salt, or electrolyte, losses.  No room for low-salt diets on the Tour trail, with savoury snacks on the bike also being important rather than predominantly sweet options which seem to be popular with cyclists.

Immune system:

Fuelling and recovery are priorities, but with the stress on light and lean bodies at their physical peak, there is also the risk of illness during an unpredictable event such as the Tour de France.  Food options shouldn’t just focus on protein, carbohydrate and fluid, but also the overall nutrient density of foods.  Intake in the lead up to multi-stage events is also important for preparing the body to be in the best condition prior.

This is just the base of the mountain when it comes to Tour de France and endurance nutrition.  Each team and individual athlete will have their own specific nutrition strategies.  Even with the best support team and planning, endurance events are unpredictable, so nutrition plans need to be flexible, and a plan B is always handy.  By the end of the Tour, cyclists will be physically and psychologically exhausted and often a bit lighter on the scales.  Sports nutrition strategies can help throughout a Tour, but are also important in transition periods between events in preparation for the next physical challenge.  

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Carbohydrates and sugars for athletes during exercise - type, total amount and teeth

Are home-made carbohydrate snacks better than gels?

Let's face it, most people eat too much sugar.  Far more sugar than our bodies need for energy levels and health.  But if you are an endurance athlete, your body needs carbohydrate, which ultimately breaks down to sugar.  Your body needs sugar during  long duration exercise to perform at its best.  If you are a strength athlete you need some carbohydrate too.  When it comes to performance, the key is to consume the right type of carbohydrate, at the right times and in the right amounts.  Not all carbohydrates and sugars are equal, but neither are individual needs, and athletes often need a mix of sugars that will be different to someone who doesn't train.   We talk about carbohydrates and sugars, but, this doesn’t mean eating a bag of lollies every day, weighed to the gram.  Far from it.  Not all sugars are equal and there is even more to the story if you train a lot.

WHAT IS SUGAR?

The word sugar automatically creates visions of sugar coated sweets, lolly pops and coloured sprinkles.  The other images that may come to an athlete’s mind with regard to sugar are carbohydrate gels, chews and sports drinks.  Sugar is everywhere, and for those of us following a largely sedentary lifestyle it is easy to eat too much.  In a country where around 2/3 of the population are overweight, sugar is rarely seen in a positive light, but for athletes there are benefits. 

All carbohydrate foods and drinks we consume are converted to sugars in the body.  However, this does not make all carbohydrate-based foods unhealthy. 

Carbohydrates are made up of chains of various sugar molecules.  These chains are broken down in the body to release individual sugars, which can be used as an effective fuel by the muscles and brain.  Sugar is not always nasty, and can be a valuable energy source for optimal human performance.  Different types of individual sugars can be used by the body, and the right balance can be beneficial for providing the best fuel to sustain endurance efforts.  Although it sounds like I am talking up the benefits of sugar, there is a time and a place for different types.  Some athletes may need to tailor their carbohydrate intake around training and competition in light of other nutrition goals, while others with elevated fuel needs and revved up metabolisms may need regular carbohydrate throughout the day.

HOW MUCH SUGAR FOR ATHLETES?

If you are an athlete that burns a lot of carbohydrate, then sugar will help to fuel performance.  But just because you train a lot, doesn't mean you necessarily need to carbohydrate load for every training session.  Every athlete has different requirements for carbohydrate and sugars based on a range of factors including gender, body weight, body composition, training program, training phase, health status, altitude and genetics.  Two people doing exactly the same training could in fact have quite different carbohydrate requirements.  An athlete’s daily carbohydrate needs can be estimated based on body weight and current training, and this can be adjusted over time to accommodate other individual factors as just listed.  

For exercise less than one hour duration, carbohydrate fuel requirements may be low, but there is evidence for performance benefits of a small amounts of carbohydrate during exercise due to potential central nervous system effects.  As the duration of exercise increases, so too does the requirement for carbohydrate, with 60-90g/hour recommended for athletes during endurance activity (or even higher for some ultra-endurance athletes working at a high intensity, up toward 110g/hour). 

I recently attended a nutrition for ultra-endurance sports symposium run by Monash University and there seems to be a wide range of carbohydrate intakes during competition and different types of training sessions.  As you may expect, many individuals find it physically difficult to consume 90g/hour during exercise, and may struggle at even half of this (45g/hour).  This is often due to gastrointestinal symptoms, which can be related to individual factors and the type of activity.  It is easier to eat and drink riding a bike at a moderate pace compared to running at elite marathon pace for example.  Some people also may simply use carbohydrate more effectively than others.  For serious athletes, it may be worth seeking a laboratory that can test your individual ability to oxidise carbohydrate and to help you work out the best type and amount of carbohydrate for during exercise. 

TYPES OF SUGAR

The recommendation in recent years has been for endurance athletes in events >2 hours duration with high carbohydrate needs (>60g/hour) should consume multiple transportable carbohydrate during exercise in a 2:1 glucose:fructose ratio.  Fructose has a different transport system for absorption from the intestine, so adding some fructose to the glucose consumed allows a greater amount of carbohydrate to be absorbed by the body.   An increasing number of people are being identified as fructose malabsorbers, and trying to increase fructose as a fuel option for exercise may be problematic in terms of gut comfort.  Fructose malabsorption may be exacerbated with exercise due to increased irritation of the gut, even though there may not be any gastrointestinal symptoms day-to-day. So it comes down to looking at maximizing carbohydrate intake within individual tolerance levels and exercise needs.

NATURAL SUGARS VS REFINED

Some endurance athletes have taken an interest in ‘natural’ forms of carbohydrate and sugars as an alternative to formulated sports products eg. gels.   This involves preparing home-made snacks rather than relying on commercial sports nutrition products.  As per my recent blog, natural sugars are not always as innocent as they may seem, and are not necessarily healthier than refined sugar.  I am all for reducing intake of processed food and additives across the board, but when it comes to athletic performance we really need to think about the type of individual sugars from a more scientific perspective.  Home-made cookies, balls and cakes are terrific, and there are a range of sweet and savoury options that work well.  The only problem is that many natural sugars are often high in fructose, which can cause major gut issues for long-duration exercise. Natural options are often low glycemic index, which means they may be more slowly digested….great if you are trying to lose weight and need help staying full for longer but not so great if you want food to empty rapidly from the stomach while exercising.  Finding the right balance of carbohydrates takes planning, and also some trial and error.  If you are set on going all natural then go for it, but if your gut is telling you ‘no’ then you may need to mix it up a bit.  Pre- and post-exercise is where unrefined carbohydrates come into their own, but during exercise the focus should be on glucose vs fructose rather than natural vs processed.

DO ATHLETES REALLY NEED ALL THAT CARBOHYDRATE?

There is so much discussion about carbohydrate as a fuel, but athletes don’t need to be carbohydrate loading for every session.  There are potential benefits of training with low fuel stores for selected training sessions to encourage physiological adaptations that optimize fuel systems.  In reality, a competitive situation may lead to low carbohydrate stores with limited carbohydrate availability, so an improved ability to rely on fat oxidation for fuelling may be of benefit. Some athletes are following the low carb trends and there is a movement by some ultra-endurance athletes to train their bodies to use predominantly fat as a fuel, replacing gels and bars with tubes of nut butter to fuel exercise.  Fat is a slow-burning fuel, so although this approach may work well for some individuals, to truly maximize endurance performance, sugar throughout will help.  Numerous studies show that faster finish times for endurance athletes correlate with higher carbohydrate intake during an event– if you can use more carbohydrate you can move faster.  However if your exercise is of shorter duration, you won’t need to be so aggressive with carbohydrate intake.  If you are not sure how much carbohydrate you need, speak with an Accredited Sports Dietitian to tailor your intake.   

WHAT ABOUT STRENGTH ATHLETES?

Strength athletes may benefit from carbohydrate prior to sessions for improved energy levels, work capacity and muscle mass gains.  So it’s not just all about protein -  carbohydrates and overall kilojoules are just as important.  Strength-based activities don’t use the same volume of carbohydrates as endurance pursuits, therefore carbohydrate needs may be more likely to be met through meals, without the need to consume large amounts during exercise.  However some athletes with very high energy requirements may benefit from taking in kilojoules, including carbohydrates, during strength sessions.

WEIGHT LOSS

Athletes trying to lose weight often reduce carbohydrates.  This can be an effective strategy, but it is important to be selective about where in the day carbohydrates are reduced and by how much, with the priority to time carbohydrate for training needs to produce the best training outcomes and adaptations.  There has been recent interest in ‘train-low’ and ‘sleep-low’ concepts of carbohydrate timing, which may improve fuel utilization but may also be appropriate to support body fat goals.

TEETH

Dental health is often compromised in athletes.  With reduced saliva production during exercise, coupled with high sugar intake and the acidity of most sports drinks, the teeth of an athlete are constantly at risk.  Dental problems are the result, so it is wise to try to reduce the contact of sugars with your teeth and try to get plenty of water rinses to reduce the risk of tooth damage.

SUMMARY

Sure, carbohydrates are beneficial for athletic performance, but this doesn’t mean you have to be on a constant carbohydrate load.  The type, timing and amount will vary according to specific exercise requirements, gastrointestinal tolerance and personal preference.  Choosing natural sugars is not necessarily better for during endurance activity.  Work on finding the right mix for your individual needs. 

Please feel welcome to subscribe to my regular newsletter, you can do so at the bottom of this page, and I am more than happy for you to share this article with others who may be interested in performance nutrition.

Further reading:

Jeukendrup, A (2011) 'Nutrition for endurance sports: marathon, triathlon, and road cycling' JSpSci 

Stellingwerff, T & Cox, G (2014) 'Systematic review: carbohydrate supplementation on exercise performance or capacity of varying durations' ApplPhysNutrMetab