Sport nutrition for endurance athletes - part II

Research studies are great especially when it comes to improving athletic performance. When the human body is required to work so hard for a specific amount of time, it's important to understand how to properly fuel the body, train the body and recover the body for health and performance gains. Effective research studies (or studies reflective of the masses) are great sources to learn from and can be a valuable tool for athletes and coaches. 
But current sport nutrition guidelines and research can only take an athlete (or coach) so far because the key is knowing how to properly apply the information into the real world. 
It's important to always consider the pros and cons when it comes to applying research into your real world for just because a research study (or the abstract which most individuals have access to) states that something works in a controlled, laboratory setting, doesn't always imply that that same message will apply to your setting. Additionally, just because a research study doesn't state something to be true or false, it doesn't mean that you won't benefit from changing your behavior/habits to help yourself reach personal health and performance related goals. 
There are many variables that can affect a research study just like there are many variables that can affect you, as the athlete. 
Never lose sight of your individual goals when you are working hard to reach them.
The best performances follow patience, hard work, no short-cuts (or cutting corners) and a smart training, pacing and fueling plan. 

As promised, here's part II of recent sport nutrition highlights:
Energy and nutrient deficiencies in female endurance athletes, Melinda Manore, PhD, RD from Oregon State University

Weight issues are prevalent among female athletes. A study involving 66 elite women indicates that 50 percent want to lose weight and 20 percent use pathogenic eating behaviors. 

Elite runners can experience amenorrhea and not have an eating disorder. Some female athletes simply do not eat enough food. The shortage of energy generally also means a shortage of calcium, magnesium, iron and vitamin D. 

Inadequate energy intake reduces estrogen. Low estrogen reduces bone mineral content; bone breaks down faster than it gets rebuilt. This happens with post-menopausal women as well as with athletes. 

Studies of women who resume menses indicate they may gain about 4 lb in the process of restoring their health. Women who lift weights and continued to train while consuming the increased energy intake were less likely to gain fat versus lean tissue. 

Marathon training strategy; periodization and diet, Trent Stellingwerff, PhD from the Canadian Sports Centre

"Training low" (low glycogen stores) is not fun; it is challenging both psychologically and physiologically. Training low is for elite athletes who have come close to maximizing their performance potential. It is not for junior athletes who have yet to maximize their athletic potential, athletes who get injured easily, power athletes who want to build muscle or athletes at risk of an eating disorder. 

Regarding weight management, Stellingwerff recommends that runners be at their racing-weight only one or two times a year. Being 4 percent to 6 percent racing weight contributes to functional weight training. 

Dietary protein and muscle reconditioning, Luc Van Loon, PhD from Maastricht University

Muscles are continually broken down and rebuilt; muscle tissue protein turns over at a rate of 1 percent to 2 percent each day. That implies that muscle tissues is renewed every 2 months. 

Protein consumed pre-exercise can be rapidly digested and will be available for protein synthesis during as well as after exercise. 

After exercise, athletes do not need to co-ingest carbohydrates with protein to augment muscle synthesis. However, carbohydrate intake is required to replace depleted muscle glycogen stores. 

A 20-25g dose of high-quality protein (such as milk, eggs or meats) ingested after exercise will effectively increase muscle protein synthesis rates. Although the optimal amount is likely dependent on the body weight of an athlete, more research is needed to determine the optimal amount of dietary protein required to maximize post-exercise muscle protein synthesis rates in various athletes in various sports. 

Clinical issues in endurance athletes, Nanna Meyer, PhD, RD from the University of Colorado

An estimated 45-85 percent of athletes complain of GI issues. 

Stress fractures escalate in runners; the higher the mileage, the higher the risk of experiencing a stress fracture. 

Cyclists are at risk for bone loss because 1) they perform a sport that is non-weight bearing and 2) they lose calcium in sweat. In 2 hours, they might lose 135 mg calcium - and this adds up over the course of months and years. 

Because calcium can be lost in sweat, athletes should consume a calcium-rich food prior to exercise to help counter sweat-calcium losses. 

Women need 30 kcal/kg fat-free body mass to support normal menstruation. They will typically resume menses in about 2-3 months. 

Protein and Weight management in long distance runners, Stuart Phillips, PhD, McMaster University

Protein is satiating. Dieters tend to eat fewer calories with a high protein meal plan as compared with a higher carbohydrate plan. 

Runners who want to lose body fat should have a higher protein intake because they will not only feel less hungry but also will experience less loss of muscle when restricting food intake. During times of energy deficit, protein needs increase. More research is needed to determine the best dose of protein to counter muscle loss. 

Consuming diets rich in dairy protein may contribute to slightly more fat loss compared with diets with low dairy protein, perhaps relating to the calcium intake. In addition, consuming dairy foods rich in calcium and vitamin D may help prevent bone mineral loss. 

Four meals a day, each providing about 20-25g protein is a wise strategy for preventing muscle loss during a weight reduction program.