Each year, I look forward to attending the Annual Meeting of American College of Sports Medicine (ACSM), because it is where I learn the latest sports nutrition news. This year, more than 6,500 sports medicine professionals and exercise scientists convened to present their latest research.
Here are just a few highlights.
- Body fat better measure than BMI. Should you be concerned if your Body Mass Index (BMI), the ratio of height and weight, categorizes your child as being overweight? According to a survey of athletes from a variety of sports, not if they are muscular. Using BMI as a measurement, 35% were classified as overweight and 4% as obese, but using body fat as a measure, only 3.5% were overweight and 3% were obese. The take-away message: looking in the mirror can often be more accurate than BMI!
- Lighter not necessarily better. Because many runners believe the lighter they are, the better they will perform, they will often go to great extremes to restrict their food intake. The problem is that food records of collegiate cross-country runners (30 males, 19 females) who trained about 60 miles per week suggests that 37% of the runners ate at least 10% less than expected and were in energy deficit; 35% ate a low-carb diets (less than 2.5 g carb/lb./day; <6g/kg/day). How much better could they perform if they were better fueled?
- Gradual weight loss maintains muscle mass. If you are in a sport that demands leanness, chipping away at fat loss is preferable to crash dieting to lose weight quickly. A case study of a figure competitor who reduced her energy intake by only 500 calories/day showed she was able to maintain her muscle mass while dropping her body fat from 15% to 8.5%. Most dieting athletes lose muscle.
- Supervised weight loss better. Can weight loss programs with self-monitoring devices be as effective as working with a health professional? When 78 obese adults were randomized to a weight loss group, an armband group, or both for 8 weeks, the group that lost the most weight received both personal guidance as well as the armband. If you want professional sports nutrition help, find your local sports dietitian by using the referral network at www.SCANdpg.org.
- Adding yoga to exercise regimen helps weight loss. Yoga is a popular form of exercise, but does it contribute to weight loss? A 12-month study with middle-age women compared a reduced-calorie diet plus either 40 minutes of aerobic exercise on 5
days/week or 40-minutes aerobic exercise plus three additional yoga sessions/week. The subjects in the yoga group lost more weight and body fat, plus they improved more in terms of endurance and flexibility. Despite the added time required to do yoga, 95% completed the program (vs. 61% of the group with no yoga). Downward dogs might lead to weight loss success! - Cross-country travel: arrive a day before competition. While nutrition certainly enhance sports performance, so does sleep. A study with athletes who flew from CT to CA to perform exercise tests suggests that flying in one day prior to the event impaired athletic performance. Hence, if you are traveling to an event that crosses time zones, you'd be wise to arrive early and invest in more time pre-event to recover-from-jet-lag. This also gives time to rehydrate and fuel optimally!
- Protein supplements don't help build muscles. If you are just starting a weight-lifting program, would protein supplements give you a muscle-building advantage? Doubtful. A study with untrained men who did 4 weeks of resistance training indicates they all had significant improvements in muscle size and strength. No significant differences were noted between those who took the protein supplements and those who had the placebo. Looks like regular meals can provide adequate protein to effectively build muscles. Instead of buying expensive supplements, enjoy a serving of a protein-rich food at each meal and snack to build muscles, along with a carbohydrate to refuel muscles. Examples: chocolate milk, apple + cheese yogurt + granola, pasta + meatballs.
- Keep food log to identify reasons for GI distress: Gastrointestinal (GI) distress is a common performance-limiting problem for many athletes, likely due to a combination of physiological, mechanical (jostling) and dietary factors. Among 30 ultra-runners, who recorded their GI symptoms four times throughout the Western States 100-Mile Run (161 km), 77% reported some type of GI issue. The most common symptoms were nausea (53%), belching (40%), flatulence (30%), and vomiting (30%). Race diet was similar in terms of carbohydrates, calories and fluids for runners with and without nausea. This suggests that factors other than nutrition contribute to GI symptoms. If you experience GI distress while running, keep food data to help detect any food culprits.
- No performance advantage for gluten-free diet. A gluten-free diet has become trendy among some athletes, even when they do not have celiac disease (and seemingly have no health reasons for avoiding gluten). Is there any performance advantage for athletes who eat a gluten-free diet? Doubtful. Among 13 competitive male cyclists with no history of celiac disease or irritable bowel syndrome, a (short-term) gluten-free diet did not improve performance, GI symptoms, well-being or intestinal injury. Maybe wheat isn't so bad, after all?
- Cold water works for most. Does room-temperature water (72° F/22° C), cold water (39° F/4° C), and an ice slurry (30° F/-1° C) offer similar cooling benefits when consumed during exercise in the heat? In a study with fitness exercisers who did three exercycle rides to exhaustion, the subjects worked longer with the slurry as compared to room-temperature water (35 vs. 31 minutes to exhaustion), but the slurry offered no huge advantage over cold water (35 vs. 34 minutes to exhaustion). Cold water is likely good enough for the average exerciser-plus it is easier to consume quickly and is more readily available during exercise.
Nancy Clark MS RD CSSD is a longtime MomsTEAM expert and sports nutritionist with a private practice in the Boston area, where she helps both fitness exercisers and competitive athletes create winning food plans. Her best-selling Sports Nutrition Guidebook, and food guides for marathoners, cyclists and soccer players, as well as teaching materials, are available at www.nancyclarkrd.com. For online and live workshops, visit NutritionSportsExerciseCEUs.com.
