Category: Articles


Protein Requirements for Athletes

A well-designed diet for an athlete is a combination of proper energy intake, proper timing, along with proper training. An energy deficient diet during training may lead to loss of muscle mass and strength, increased susceptibility to illness, and increased prevalence of overreaching and/or overtraining (7). People who follow a general fitness program can generally meet their nutritional needs with a healthy, well-balanced diet. However, the caloric and protein needs of a highly trained athlete are different
and will be discussed here.

Considerable debate ensues regarding the proper intake of protein for athletes. The current recommended level of protein intake (0.8 g/kg/day) is estimated to be sufficient to meet the needs of nearly all (97.5%) healthy men and women age 19 years and older (2). This amount of protein intake may be appropriate for non-exercising individuals, but it is “likely not suffi cient to off set the oxidation of protein/amino acids during exercise (approximately 1 –5% of the total energy cost of exercise)” (2). If an athlete does not ingest sufficient amounts of protein, he or she will maintain a negative nitrogen balance, which can increase protein catabolism and slow recovery (7). Nitrogen balance is quantifed by calculating the total amount of dietary protein that enters the body and the total amount of the nitrogen that is excreted (9). Table 1 provides general guidelines for protein and caloric intake based on the level of activity.

It is important to remember that not all protein is the same. Proteins differ based on the source, the amino acid profile and the methods of isolating the protein (7). Great dietary sources of low-fat, high-quality protein are skinless chicken, fish, egg whites and skim milk while the highest quality supplemental sources are whey, colostrum, casein, milk proteins and egg protein (7). The Food
and Agriculture Organization (FAO) established a method for determining the quality of a protein source by “utilizing the amino acid composition of a test protein relative to a reference amino acid pattern and then correcting for differences in protein digestibility,” (4).

Two of the most widely used protein supplements are casein and whey, which can both be found in milk products. Research has demonstrated that “whey protein elicits a sharp, rapid increase of plasma amino acids following ingestion, while the consumption of casein induces a moderate, prolonged increase in plasma amino acids that was sustained over a 7-hour postprandial time period,” (1). The International Society of Sports Nutrition (ISSN) recommends that athletes obtain protein through whole foods, and when supplements are ingested they should contain both casein and whey “due to their ability to increase muscle protein accretion,” (2).

While casein and whey have been found to be beneficial, other research exists to support the benefits of leucine. Approximately one third of skeletal muscle protein is made up of the branched-chain amino acids (BCAA), leucine, isoleucine and valine (8). Research suggests that of these three, leucine plays the most significant role in stimulating protein synthesis (5). Therefore, supplementation
of branched-chain amino acids may be beneficial to athletes.

Researchers at the Department of Human Biology at Maastricht University in the Netherlands, conducted a study to determine post-exercise muscle protein synthesis and whole body protein balance following the combined ingestion of carbohydrates with or without protein and/or free leucine (6). Eight male subjects were randomly assigned to three trials in which they consumed drinks containing carbohydrates, carbohydrates/protein, or carbohydrates/protein/leucine following 45mins of resistance exercise. Results of the study showed that whole body protein breakdown rates were lower, and whole body protein synthesis rates were higher in the carbohydrate/protein and carbohydrates/protein/leucine trials compared with the carbohydrate trial. The addition of leucine resulted in a lower protein oxidation rate compared with the carbohydrate/protein trial. The study concluded that
co-ingestion of protein and leucine stimulates muscle protein synthesis and optimizes whole body protein balance compared
with the intake of carbohydrates only (6).

BCAA supplementation has been shown to be particularly beneficial during aerobic exercise because of an increase in the free tryptophan/BCAA ratio (5). During prolonged aerobic exercise, the amount of free tryptophan increases and therefore the amount of tryptophan entering the brain increases, resulting in fatigue (5). BCAAs are transported to the brain through the same carrier as tryptophan, so when BCAAs are present in the plasma, in signifi cant amounts, they may decrease the amount of tryptophan reaching the brain, therefore decreasing feelings of fatigue (2). It has been suggested that the recommended daily allowance (RDA) for leucine alone should be 45 mg/kg/day for sedentary individuals, and even higher for active individuals (8). A deficiency in BCAA intake from whole foods can be supplemented by consuming whey protein (2).

In conclusion, major organizations recommend athletes consume more than the RDA for protein, approximately 1.4 – 2.0 g/kg of body weight/d (2,4). Every attempt to obtain protein from whole foods is ideal; however supplementation is a safe way of obtaining the needed amounts of protein when necessary.

Table 1. Caloric and Protein Intake Guidelines

Activity Level Caloric Intake Protein Intake
General Activity 25 -35 kcals/kg/day 0.8 – 1.0 g/kg/day
Strength Training Athletes 50 – 80 kcals/kg/day 1.4 – 1.8+ g/kg/day
Endurance Athletes 150 – 200 kcals/kg/day 1.2 – 1.4 g/kg/day

Source: The Position Statement from the Dietitians of Canada, the American Dietetic Association, and the American College of Sports Medicine, Canadian
Journal of Dietetic Practice and Research in the Winter of 2000, 61(4):176-192 (3).

References

1. Boirie Y, Dangin M, Gachon P, Vasson MP, Maubois JL, and Beaufrere, B. Slow and fast dietary proteins differently modulate postprandial protein accretion. Proceedings of the National Academy of Sciences of the United States of America 94(26): 14930 – 5, 1997.

2. Campbell, B, Kredier, R, Ziegenfuss, T. et al. International Society of Sports Nutrition position stand: Protein and exercise. Journal of the International Society of Sports Nutrition 4(8), 2007.
3. The Position Statement from the Dietitians of Canada, the American Dietetic Association, and the American College of Sports Medicine. Canadian Journal of Dietetic Practice and Research 61(4): 176 – 192, 2000.
4. Darragh, A, and Hodgkinson, S. Quantifying the digestibility of dietary protein. The Journal of Nutrition 130: 1850S – 1856S, 2000.

5. Kimball, SR, and Jefferson, LS. Signaling pathways and molecular mechanisms through which branched-chain amino acids mediate
translational control of protein synthesis. Journal of Nutrition 136(1 Suppl): 227S – 31S, 2006.

6. Koopman R, Wagenmakers AJ, et al. Combined ingestion of protein and free leucine with carbohydrate increases post-exercise muscle protein synthesis in vivo in male subjects. American Journal of Physiology Endocrinology and Metabolism 288(4): E645 – 53, 2005.

7. Kreider, RB, Wilborn, CD, Taylor, L, Cambpell, B, et al. ISSN exercise & sport nutrition review: Research & recommendations. Journal of the International Society of Sports Nutrition 7(7.2), 2010.

8. Leucine supplementation and intensive training. Sports Medicine. 27(6): 347 – 58, 1999.

9. Rand WM, Pellett, PL, and Young, VR. Meta-analysis of nitrogen balance studies for estimating protein requirements in healthy adults. American Journal of Clinical Nutrition 77(1): 109 – 27, 2003.

 

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LADIES this is for you

I was visiting womenshealth.com and I came across an article that is perfect for the women who don’t like to lift weights because of the fear of getting “BIG” or “BUFF”

What I hear the most is this: “I don’t want to get big I just want to tone!” Well to tone you have to lift weights and more than the 5 lb dumbbells.

Lose Your Fear of Weightlifting

By Adam Campbell

Just because you’re not vying for 20-inch biceps or thunderously strong thighs like the muscle heads in the gym doesn’t mean you should shun the weight room. Lifting weights gives you an edge over belly fat, stress, heart disease, and cancer—and it’s also the single most effective way to look hot in a bikini. Yet somehow women are still hesitant: Only about a fifth of females strength train two or more times a week.

Here are 12 reasons you shouldn’t live another day without hitting the weights.

  1. You’ll Lose 40 Percent More Fat: If you think cardio is the key to blasting belly fat, keep reading: When Penn State researchers put dieters into three groups—no exercise, aerobic exercise only, or aerobic exercise and weight training—they all lost around 21 pounds, but the lifters shed six more pounds of fat than those who didn’t pump iron. Why? The lifters’ loss was almost pure fat; the others lost fat and muscle.

    Other research on dieters who don’t lift shows that, on average, 75 percent of their weight loss is from fat, while 25 percent is from muscle. Muscle loss may drop your scale weight, but it doesn’t improve your reflection in the mirror and it makes you more likely to gain back the flab you lost. However, if you weight train as you diet, you’ll protect your hard-earned muscle and burn more fat.

  2. Your Clothes Will Fit Better: Research shows that between the ages of 30 and 50, you’ll likely lose 10 percent of your body’s total muscle. Worse yet, it’s likely to be replaced by fat over time, says a study. And that increases your waist size, because one pound of fat takes up 18 percent more space than one pound of muscle.
  3. You’ll Burn More Calories: Lifting increases the number of calories you burn while your butt is parked on the couch. That’s because after each strength workout, your muscles need energy to repair their fibers. In fact, researchers found that when people did a total-body workout with just three big-muscle moves, their metabolisms were raised for 39 hours afterward. They also burned a greater percentage of calories from fat compared with those who didn’t lift.

    Lifting gives you a better burn during exercise too: Doing a circuit of eight moves (which takes about eight minutes) can expend 159 to 231 calories. That’s about what you’d burn if you ran at a 10-mile-per-hour pace for the same duration.

  4. Your Diet Will Improve: Exercise helps your brain stick to a diet plan. University of Pittsburgh researchers studied 169 overweight adults and found that those who didn’t follow a three-hours-a-week training regimen ate more than their allotted 1,500 calories a day. The reverse was also true—sneaking snacks sabotaged their workouts. The study authors say both diet and exercise likely remind you to stay on track, aiding your weight-loss goals.
  5. You’ll Handle Stress Better: Break a sweat in the weight room and you’ll stay cool under pressure. Scientists determined that the fittest people exhibited lower levels of stress hormones than those who were the least fit. Another study found that after a stressful situation, the blood pressure levels of people with the most muscle returned to normal faster than the levels of those with the least muscle.
  6. You’ll Be Happier: Yoga isn’t the only Zen-inducing kind of exercise. Researchers found that people who performed three weight workouts a week for six months significantly improved their scores on measures of anger and overall mood.
  7. You’ll Build Stronger Bones: As you age, bone mass goes to pot, which increases your likelihood of one day suffering a debilitating fracture. The good news: A study found that 16 weeks of resistance training increased hip bone density and elevated blood levels of osteocalcin—a marker of bone growth—by 19 percent.
  8. You’ll Get into Shape Faster: The term cardio shouldn’t describe only aerobic exercise: A study found that circuit training with weights raises your heart rate 15 beats per minute higher than if you ran at 60 to 70 percent of your max heart rate. This approach strengthens muscles and provides cardiovascular benefits similar to those of aerobic exercise—so you save time without sacrificing results.
  9. Your Heart Will Be Healthier: Researchers at the University of Michigan found that people who did three total-body weight workouts a week for two months decreased their diastolic blood pressure (the bottom number) by an average of eight points. That’s enough to reduce the risk of a stroke by 40 percent and the chance of a heart attack by 15 percent.
  10. You’ll Be Way More Productive: Lifting could result in a raise (or at least a pat on the back from your boss). Researchers found that workers were 15 percent more productive on days they exercised compared with days they didn’t. So on days you work out, you can (theoretically) finish in eight hours what would normally take nine hours and 12 minutes. Or you’d still work for nine hours but get more done, leaving you feeling less stressed and happier with your job—another perk reported on days workers exercised.
  11. You’ll Live Longer: University of South Carolina researchers determined that total-body strength is linked to lower risks of death from cardiovascular disease and cancer. Similarly, other scientists found that being strong during middle age is associated with “exceptional survival,” defined as living to the age of 85 without developing a major disease.
  12. You’ll Be Even Smarter: Muscles strengthen your body and mind: Brazilian researchers found that six months of resistance training enhanced lifters’ cognitive function. In fact, the sweat sessions resulted in better short- and long-term memory, improved verbal reasoning, and a longer attention span.

So Ladies what are you going to do when you go to the gym? 😉