Nutrition Corner: May 2012

WHAT TO EXPECT WITH GROWING SWIMMERS AND THEIR CHANGING BODIES

5/23/2012

Even though swimmers get plenty of exercise, questions about their growth still linger. Is my swimmer growing normally? Why is he slow to develop? Is she filling out too early? When parents and swimmers know what to expect with growth, it can calm unnecessary fears and divert potentially harmful interventions.
Here, I address some common concerns about body weight in growing swimmers:

“My daughter has a little ‘extra’ around the middle. She’s active and seems to eat well—and thankfully she’s not worried about it, but I’m a little concerned.”

In girls, the body prepares for the important job of menstruation by laying down body fat in the area of the tummy. Sometimes this is interpreted as abnormal weight gain, but for most healthy children, this is normal.

The average age of menses (onset of period) is 12.5 years, but this varies with ethnicity and weight status, and can be earlier or later. Once puberty starts (usually around age 10), height growth takes off and girls magically thin out. Once height reaches its peak, body weight is redistributed to the rear, hips, breasts, backs of arms, and thighs, transforming the body into a curvy womanly figure. If you notice extra weight gain overall, more than the normal tummy trend and “filling out” of puberty, it may be an indicator of overweight or obesity.

“My son seems to be the smallest in the class. All the girls are taller than he is, and he doesn’t seem to be getting muscular.”

In general, girls and boys grow at very different rates. Girls outpace boys early on, then boys catch up and surpass girls during later adolescence. Boys generally lag behind girls, starting puberty about 2 years later (around age 12).

Not only do boys get their turn, it lasts longer. Boys end up taller and more muscular than girls. Once puberty hits, testosterone levels rise and visible muscle growth occurs.

“My daughter seems to be losing weight. Should I be concerned?”

Growing swimmers are just that—growing. In other words, they are meant to gain weight and stature until age 16 (girls) or 18 (boys) on average. If your swimmer is losing weight, he or she may not be eating enough to balance the energy expenditure associated with swimming. Over time, lack of weight gain can result in stunted stature (limited height growth).

“I think my son is gaining too much weight.”

The best way to determine whether your swimmer is on target with growth is to check his growth chart with the pediatrician. Normal growth follows a typical trend or growth channel throughout childhood. If weight increases from the usual growth pattern, this indicates that excess weight gain is occurring. The good news is that swimming is a calorie-burning sport. Make sure swimmers are eating a healthy balance of foods and scale back on sweets, sodas and high-fat snack foods.

Bottom Line: Know what to expect with your swimmers growth. Boys and girls grow and deposit muscle and fat tissue differently and their overall timing is different. Growth is a gradual acceleration in weight and height, and weight loss is not normal. Know when weight gain is getting out of hand by checking growth periodically.

Knowing these normal growth trends can help promote a healthy weight and avoid potentially negative interventions, like putting a little girl with a belly on a diet, pushing protein in young boys for bigger muscles, or ignoring slowed growth or too much weight gain.

Jill Castle, MS, RD, LDN is a registered dietitian and child nutrition expert. She is the co-author of the upcoming (2013) book, Fearless Feeding: How to Raise Healthy Eaters from High Chair to High School, and creator of Just The Right Byte, a child and family nutrition blog. She lives with her husband and four children (one swimmer!) in Nashville, TN.

Article from USASwimming.org

PUMPING UP THE IRON IN THE SWIMMER’S DIET

4/13/2012

BY JILL CASTLE, REGISTERED DIETITIAN AND CHILD NUTRITION EXPERT

Popeye the Sailor Man got it right. By focusing on iron (spinach), he transformed himself into a strongman, ready to save the day. He knew that iron was an important nutrient to health. While the swimmer won’t experience Popeye’s immediate transformation into a muscle wielding superhuman, he will strengthen his immune system and energy level.

Where iron is and what it does
There are two sources of iron in our food supply: heme iron (from meats and fish) and non-heme iron (from plant foods). While both are absorbed and utilized by the body, heme iron sources are better absorbed than non-heme iron foods.

Iron helps the body transport oxygen to cells. This is important for the swimmer, as a deficiency in iron will limit oxygen delivery to all cells, including the all-important muscles.

How iron needs change and what they are
As swimmers grow, iron needs increase because blood volume expands naturally. Iron requirements are as follows:

Male:

9-13 years: 8 mg per day
14-18 years 11 mg per day

Female:

9-13 years: 8 mg per day
14-18 years: 15 mg per day

The female swimmer almost doubles her iron needs when puberty hits, this is due to blood volume increases, and blood losses (menstruation).

Signs of not getting enough
Fatigue or lack of energy, paleness, low body temperature, chronic infections/colds, and reduced academic performance are indicators of a potential problem. Iron deficiency is caused by too little iron in the diet and can lead to iron-deficiency anemia. Swimmers who are lacking iron in their diet will need to focus on getting more. Swimmers who have anemia may be prescribed an iron supplement to rejuvenate their iron stores, in addition to an iron-rich diet.

At-risk populations
Swimmers and other endurance athletes are at higher risk for iron deficiency anemia. This is due to blood cell breakdown during exercise, making iron more of a concern. Children and teens who are picky eaters, dieters, meal skippers or who have a poor quality diet (heavy on junk, light on nutritious options) are at risk for iron deficiency. Lastly, female swimmers have a double-whammy—greater iron needs with growth and blood loss due to menstruation.

Iron-Rich foods
Popeye was strong because he ate his spinach, but other foods offer the swimmer a punch of iron too. Organ meats (liver), red meats, poultry and fish are the richest sources of heme iron and best absorbed by the body. Non-heme iron sources such as beans, tofu, dark leafy vegetables (spinach, kale), fruits (raisins), iron-fortified cereals, quinoa, iron-fortified breads, bagels and muffins, edamame (soy), almonds and cashews require a little help from Vitamin C to boost the iron absorption.

Tips for getting more

Plan to include iron-rich foods at each meal.
Vitamin C promotes iron absorption of non-heme sources. Pair citrus juices, fruits such as strawberries and mango, and other sources of vitamin C with plant-based iron-rich foods.

Example: iron-fortified cereal with raisins and a glass of orange juice