A winning diet for active children (Part 2)
by Dr Helen O'Connor
"High protein", "low fat", "high carbohydrate", supplements, energy bars/drinks, etc are but a few of the myriad of diets and "nutritional aids" endorsed by some coaches and sports magazines for active individuals. It's no wonder then that parents are confused and at a loss when it comes to planning a suitable diet for their active children.
If you have a child who is actively engaged in recreational or competitive sports and you would like to know the secret to a winning diet for them, read on. In this exclusive interview with Dr Helen O’Connor, she addresses the key nutrients that constitute a winning diet for your active child and dispels some food-related myths that abound in the sports arena.
Dr Helen O’Connor is a sports dietitian recognised as an authority on sports nutrition. She is a lecturer in Exercise Biochemistry and Sports Nutrition at the University of Sydney and dietitian to the New South Wales Institute of Sport, the Sydney Swans and Canterbury Rugby League. Helen also runs a private practice at Sydney Sport Medicine. She is the immediate past president of Sports Dietitians Australia.
A continuation of "A Winning Diet for Active Children-Part I" by Dr Helen O'Connor, addressing: Pre, During and Post-Event Meals, Carbohydrate Loading, Nutrients of Concern, Use of Ergogenic Aids and Protein Supplements.
Interview with Dr Helen O'Connor
by Lauren F. Ho
Nutrition Manager/Dietitian
Lauren: What's a typical pre-event meal for a child athlete?
Dr O'Connor: Surprisingly, there's little research in this area. Guidelines come from practical experience rather than science. Most people feel more comfortable if they've eaten at least 2 hours before they compete to allow time for the meal to empty from the stomach, while others prefer 3 to 4 hours.
The ideal foods are ones that are familiar to the athlete so that they are not something that they have not tried before. They are also generally high in carbohydrate, fairly low in fat and contain some protein. Ideal types of combinations are breakfast cereals, bread, fruits, fruit juice, milk and yoghurt. Fat delays the digestion process, so lower fat options are preferable at this time.
Lauren: What about meals during exercise?
Dr O'Connor: During exercise, the most important nutritional factor to consider is prevention of dehydration. Sports drinks are particularly good in this situation because they are very easily digested, provide liquid energy without the bulk to boost energy and they aid the hydration process. In practice, many athletes use a combination of water, sports drinks, solids (e.g. bananas, bread and honey and cereal bars) and special sports foods (e.g. sports bars, carbohydrate gels) to meet their energy needs during exercise.
Lauren: How about post-event meals?
Dr O'Connor: At the end of competition or training, getting CHOs immediately after exercise (ideally within 30 minutes) speeds up the rate of CHO (glycogen replenishment) in the muscles. There is evidence that foods of high Glycemic Index (GI)* tend to work a little faster. Therefore if there is not much time between events, then you would probably aim for foods that are more easily digested and absorbed (hence high GI foods). Here again, sports drinks and cereal bars are good, certain types of fruits e.g. watermelon are high in GI and therefore ideal. You may aim for a rice meal; jasmine rice is high in GI to enhance the recovery process.
Just as important is to drink enough fluids: an athlete would need to drink 1.5 times the fluid loss in order to fully rehydrate.
* Glycemic Index (GI) is a method used to rank foods according to how they affect our blood glucose levels. It compares the blood glucose levels after equal carbohydrate portions of foods are consumed and ranks them relative to a standard (usually glucose or white bread).
Lauren: What is Carbohydrate (CHO) Loading? Please elaborate.
Dr O'Connor: CHO loading is a technique used to replenish glycogen stores by people who do prolonged strenuous exercise (eg. marathons, triathlons). Having additional CHO stored as glycogen in muscles will keep that person exercising longer and stronger. Most kids will not need to use this technique because they should not be doing such strenuous exercise. The only exception is perhaps in late adolescence when some may start to participate in longer, more endurance based events (eg. triathlons).
Nowadays, athletes who do large amounts of endurance training (eg. marathon and triathlon training) taper their training and eat more CHO two to three days before the event to load their glycogen stores. There is no need to deplete glycogen stores using a low carbohydrate diet prior to glycogen loading.
Lauren: Are there any other nutrients of concern, e.g. iron or calcium?
Dr O'Connor: Dietary surveys carried out in the general Australian population show that kids do not consume enough calcium, iron and zinc. So, it's very important for all children, including little athletes to eat a balanced diet. There is evidence that athletic individuals need more iron in particular because there is increased iron use, especially with heavy training.
They also need to consume enough calcium to build strong bones. Exercise is undoubtedly fabulous for bone health. However, strenuous training can often result in female athletes losing their menstrual cycle. This predisposes them to lower bone density or osteopenia and may increase their risk for stress fractures in the short term and in the long term, osteoporosis. Athletes often seen with this problem are those who restrict weight, such as gymnasts, or endurance runners, ballet dancers, figure skaters and people who are very body image conscious. These athletes need dietetic and medical assistance.
Lauren: What are your views on the use of ergogenic aids such as creatinine monohydrate among young athletes? Would you recommend their use?
Dr O'Connor: I would recommend that children aim to optimise sports performance through good training, adequate rest, and a healthy balanced diet. Many supplements are not well-researched, especially with respect to potential long term health risks.
Creatinine Monohydrate (CM) has been aggressively researched and there is evidence of it being ergogenic (performance enhancing) for certain activities/events. However, there probably isn't enough research into its long-term risks, particularly if children decide to take it from a young age. I would not recommend CM for young athletes. It may be useful for some adult athletes who can appreciate the possible risks and who are at a point where they have done everything else possible to improve performance (eg all their training, rest and an excellent diet). For these athletes, taking a supplement like CM may provide a very, very small but still important improvement in performance.
Young athletes have so much potential improvement left that we would like them to maximize their training and dietary intake first before they even consider use of ergogenic aids like CM.
There was a wave in Australia where some adolescent athletes were taking CM but it's now subsided. I think the concern about many of the supplements is that we don't know enough about the health effects after long-term use, especially in youngsters.
Lauren: There have been concerns about too much protein in the diet of athletes leading to kidney failure. Is that still a concern?
Dr O'Connor: There were concerns that a group of athletes, particularly body building & weight lifting athletes were placing too much focus on protein and too little on a well-balanced diet. It's still the case today. Good research shows that more than 2 g of protein per kg body weight per day does not have any benefit in making lean body mass increase any faster.
Some body builders eat something like 4 to 6 g of protein per kg body weight per day. There were concerns that it would place an extra load on their kidneys. Surprisingly, they do not appear to suffer any major ill effect from this eating strategy. While protein is important for growing bodies, 1-2 g per kg per day should be ample for active children.
Recently, in Australia, there was a wave of popularity of the higher protein, lower CHO diet, called the Zone Diet. Diets such as this are quite dangerous for children because they are not well balanced and they do not provide adequate nutrition for children. Children need CHO to grow, stay healthy and concentrate in school. Youngsters needing to lose weight should consult with a dietitian for specialised advice.
Lauren: What's your view on Protein supplements for children?
Dr O'Connor: Again, we would aim that children get their protein from food. If a supplement is needed, it would likely be a balanced liquid meal which contains protein, CHO, multivitamins and minerals. So, it's actually like "a meal in a glass" and all it does is to provide a convenient way to get additional energy (kilojoules/calories) which can be helpful for busy, active children before or after sport.
A liquid meal is useful in children with a very fast metabolism and those who do large amounts of physical activity. These children may struggle to eat enough energy to keep their body fuelled for training and growing at the same time (particularly teenage boys during their growth spurts). A liquid meal on top of their regular intake can help to meet these additional needs in a convenient and balanced way.
Lauren: One final question. Do you have a favourite recipe for a smoothie?
Dr O'Connor: Yes, you can find this in my recipe book, "The Taste of Fitness".
Mango Smoothie (serves 1)
1 cup / 250 ml reduced fat milk
¼ cup low-fat vanilla yoghurt
1 tablespoon skim milk powder
2 teaspoons honey (optional)
4 ice cubes
½ mango, stoned, peeled and chopped
Method:
Place milk, yoghurt, milk powder, honey (if using), ice cubes and mango in a food processor or blender and process until smooth.
Pour into a serving glass and serve immediately.
Per serve: 295 calories, 47 g CHO, 5 g Fat
Note: You can replace mango with 1 banana for a banana smoothie.