By Nancy Clark, MS, RD, CSSD
In this era of highly competitive sports, more and more endurance athletes are eagerly seeking information on how to fuel optimally. Performance nutrition is also of interest to Marines, special operations troops such as the Navy Sea, Air and Land (SEAL) teams, and others in the military who need to perform at a very high level to both survive and to carry out their missions. Hence, effective fueling practices are a topic of great interest and research for the US Armed Forces.
At this year's annual meeting of the American College of Sports Medicine (the nation's largest group of sports medicine professionals, exercise scientists, and sports nutrition researcher; www.acsm.org), civilian as well as military exercise scientists presented the results of their recent nutrition research, some of which I have highlighted below. This information might be of interest to you, whether you are a competitive runner—or a soldier—who trains for hours in the summer heat, winter cold, at high altitude, or for in preparation for a strenuous event—be it a marathon, military mission, Ironman triathlon, or an adventure race. Regardless of your reason for running, by fueling your body wisely and well, you can greatly impact your ability to perform optimally today as well as invest in your future health and well-being.
Highlights of research on nutrition for military performance:
• To become a Navy SEAL, you have to go through SEAL Qualification Training. A survey of 264 of these serious “military athletes” indicates their diets rated only 56 out of 100 on the Healthy Eating Index. This is slightly lower than the score of 59 for the general US population. To the disadvantage of these trainees, their dietary patterns were low in health-protective fruits, vegetables, whole grains and fish, but high in health-eroding refined foods with added sugar, fat and alcohol. This type of eating pattern promotes inflammation. By improving their food choices (more colorful fruits, vegetables, whole grains, healthy fats), they could reduce systemic inflammation, which could enhance recovery from training, boost immune response, and help them maintain better health. As you know, an injured or sick runner (or soldier) is not an asset to any team.
• Marines in training for acceptance to Special Operation Forces exercise extremely hard during their training program. One might think they would suffer from long-term undesired weight loss. Not the case. After each period of intentional severe food deprivation, the trainees manage to restore the significant amount of weight they lost. For example, in the toughest part of the 261 day training program (days 115-123), the men burned about 6,400 calories a day. They had access to only 2,400 calories of food. That’s about 4,000 calories a day less than they needed! They lost, on average, 11 pounds (4.9 kg). The Marines intuitively returned to their baseline weights after that training period, when they had access to adequate fuel. As a runner who might have dieted pre-event to get to your desired “racing weight”—only to quickly regain the pounds post-event—you may know first-hand how the body works hard to defend a genetic weight. Weight is more than a matter of willpower.
• Speedy recovery from strenuous exercise is of key interest to military personnel (and runners). Beta-hydroxy-beta-methylbutyrate (more commonly called HMB; a natural by-product of protein/leucine metabolism) has been shown to enhance muscle recovery from high intensity exercise. Would HMB with supplemental probiotics (gut microbes that enhance protein absorption) be a way to enhance soldiers’ muscle recovery? To find the answer, soldiers took HMB + probiotics during 2 weeks of intense military training (carrying ~77 pounds (35 kg) of equipment while marching 16-19 miles (25-30 km) per night in tough terrain). Results of this study suggest that HMB supplementation reduced the inflammatory response to intense training. Combining HMB with the probiotic Bacillus coagulans was even more beneficial than HMB alone in maintaining muscle integrity during the intense military training.
The question now arises: Can runners who eat a high quality diet with leucine-rich foods (meat, fish, chicken, cheese, whey) + probiotic-supporting fiber-rich foods (vegetables, fruits, whole grains, nuts) reap the same benefits? Sounds like a winning combination to me!
• Staying healthy is important for soldiers and runners alike; neither have time for illness due to upper respiratory tract infections (URTIs) such as colds. Would taking a high does of Vitamin D, which has been shown to improve immune function, offer protection? To answer that question, Marines in basic training received daily for 12 weeks either 1,000 IUs of Vitamin D-2 (the RDA is 600 IU) or a placebo. The majority (72%) of recruits reported getting a URTI during the 12 weeks. The high dose of Vitamin D did not offer a protective effect in this highly stressful environment. Perhaps you could instead focus on having clean hands and getting adequate sleep?
• Now that women can perform combat duty, a question arises: How well can the women perform physically compared to the men? To find the answer, 302 marines underwent comprehensive testing including strength, flexibility, balance, power, agility, and physical fitness tests (pull ups, push ups, sit ups, bench press, 2-mile run, etc.). They then were stratified into three groups according to the test results, regardless of sex or body fat: best (all men), middle (mostly men), worst (mostly female).
When compared by sex, the men, understandably, tended to have less body fat—except when compared to the best performing women. The amount of the male or female marines’ muscle-mass determined athletic performance more so than their body fatness. The best-performing men and women in groups one and two had significantly more muscle than the men and women in group three. The researchers concluded that muscle mass may have a stronger association with performance during strength, aerobic, and anaerobic tests than does percent body fat. This offers a good example of how the leanest athlete is not inherently the best athlete. For some runners, building more muscle might be more important than losing body fat.
Sports nutritionist Nancy Clark MS RD CSSD has a private practice in the Boston-area (Newton; 617-795-1875), where she counsels both fitness exercisers and competitive athletes, teaching them how to eat to win. Her popular Sports Nutrition Guidebook, and food guides for marathoners and novice runners are available at nancyclarkrd.com.