Each year, I look forward to attending the Annual Meeting of the American College of Sports Medicine (ACSM). That’s where I learn the latest sports nutrition news. This year, more than 6,500 sports medicine professionals and exercise scientists convened in San Diego to present their latest research. Below are just a few highlights.
- Should you be concerned if your Body Mass Index (BMI; a ratio of height and weight) categorizes you as being overweight? Not if you are muscular. In a survey of athletes from a variety of sports, 35% were classified as overweight and 4% as obese. Body fat measurements, however, indicated only 3.5% were overweight and 3% were obese. Looking in the mirror can often be more accurate than BMI!
- Runners commonly believe the lighter they are, the better they will perform. Thus, many go to great extremes to restrict their food intake. Food records of collegiate cross-country runners (30 males, 19 females) who trained about 60 miles per week suggests 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 better fueled…?
- If you are in a sport that demands leanness, chipping away at fat loss ispreferable 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.
- 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 help with weight management, find your local sports dietitian by using the referral network at www.SCANdpg.org.
- 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!
- While nutrition certainly enhances 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 jetlag. This also gives time to rehydrate and fuel optimally.
- 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.
- 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 and exercise data to help detect the contributing culprits.
- 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?
- 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.
Sports nutritionist Nancy Clark MS RD CSSD has a private practice in the Boston-area (Newton; 617-795-1875), 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.