Found on Ironman.com and written by John Post, MD
Lean out and speed up without endangering your bone health.
In triathlon, you’ll overhear conversations about racing weight as often as you will the weather. One thing is clear: triathlon is a sport where being light on your feet is rewarded. The endurance sports author Matt Fitzgerald poses the issue by asking a simple question: what would it feel like to set out on a run weighing 10 pounds less than you do right now?
Research indeed supports leanness as an indicator of performance, ability, and speed: “Most of the studies and articles seem to suggest that if you lose 10 pounds, you save approximately 20 seconds per mile. In other words, it translates into a minute saved in a 5K,” says Alysia Robichau, M.D. of the Memorial Hermann IRONMAN Sports Medicine Institute in The Woodlands, Texas. She adds that with all weight loss comes a loss of either fat or muscle, and that there is a delicate balance between losing fat (good) versus lean muscles (bad). She adds that depending on the athlete’s body fat percentage, losing muscle may not improve running times or fitness levels.
In short, not every athlete should aim to be “skinny.” Skinny does not imply muscle strength, tone, endurance or talent. And worse, athletes with very low body fat are at risk for a host of problems far more serious than loss of speed.
Danger #1: Stress fractures
Poor bone health, for runners and triathletes, can lead to the dreaded stress fracture, the most common of which occur in the feet or tibia (the pelvis and femur are increasingly common as well). With any injury, pain that increases with training and alters normal activity, (walking as one example) needs to be evaluated to continue high levels of training. Knowing your limits and listening to your body regarding pain in bones can help diagnose and prevent stress fractures, which can take up to eight weeks to heal.
Tool kit: Food fixes
The key to maintaining bone health while losing fat lies in nutrition. It takes a well balanced meal plan to support 30 to 50 miles a week and to keep triathletes away from stress fracture territory. You can start losing fat by eating better proportions and by balancing proteins, carbs and fat (macronutrients). Proper consumption of micronutrients such as calcium and vitamin D can also help. If you are prone to stress fractures, consult a dietician for help with putting together a plan.
Another way to achieve bone health is through strength training, which will result in decreased body fat and increased lean muscle, thus improving both your VO2 max and speed potential.
Danger #2: Low bone mineral density
The effect of body weight on bone mineral density is especially important for female triathletes, who are especially sensitive to body weight and image issues. Bone density is part of something called the “female athletic triad,” which begins with amenorrhea (absence of periods), is marked by a low bone density (leading to osteopenia and osteoporosis), and can result in an increased risk for stress fractures. The cycle commonly begins in female athletes after they stop menstruating, due to high training levels and low body fat. For female IRONMAN athletes, it’s important to get an evaluation.
Tool kit: BMD testing
Real Simple Magazine recently included Bone Mineral Density testing on its list of medical tests every woman should have. The test is called a DXA, and is simple, safe, noninvasive and painless. Much like having an X-ray, you lie fully clothed on a table while a machine scans your hips, spine and in some cases your wrists. That’s it.
The test will determine if your BMD is low enough to put you at risk for osteoporosis, a disease that leads to thinning of the bones making them more susceptible to fracture. Although we associate the risk of fracture with the elderly, some of our athletic peers are also in this group. And although the average age for menopause is 51, it’s not at all uncommon to begin in ones 40’s or even 30’s. (Some women will lose up to 30 percent of their bone mass in the five to seven years following menopause.)
Knowing your BMD will arm you with the information you need to get your bones healthy again, as well as achieving your optimal racing weight. The data will prove useful as a lifelong foundation for proper dietary habits (such as increased vitamin D or calcium) and exercise regimens. It can even help you manage other medical issues like hypertension or diabetes with medications that do not contribute to bone mineral loss if encountered. In short, you’ll be turning an unknown into a know—always a good idea in this sport.
Now get out there, do your best, and “break a leg” as they say in show business.
John Post is a six-time IRONMAN World Championship finisher and serves as the medical advisor for Training Bible Coaching.