This is the first part of a multiple part series, which will enable you to make some informed decisions about your nutrition intake. Information is presented in detail, but as other things in life, nutrition is not a cut and paste issue. You will have to make some decisions for this program truly to work. With that said, this information is presented for those individuals striving to improve physical performance. This is also great for bodybuilders trying to break through to the next level by adding some additional muscle mass.
The amount of individuals participating in athletic endeavors has broadened to greater lengths than at any time period in the history of civilizations. At any given time millions of individuals and teams will be searching their souls to find out just what they are made of. Strongmen competitions, military activities, triathalons, rugby, soccer, wrestling, ultimate fighting, and many more can be the preferred challenge. Each in it’s own right very strenuous and demanding. There are many equally important constituents of effective training, and not eating for performance can leave athletes gasping for air and wondering what went wrong.
Extensive research in the field of sports nutrition has shown the possible implications, both positive and negative, of an athlete’s diet. Athletes make efforts through training, conditioning, and practice to improve performance. A critical link in this process is proper nutrition. Improper nutrition can not only hinder performance, but is a detriment to overall physical health. The macronutrients (water, carbohydrates, proteins, and lipids) and micronutrients (vitamins and minerals) can all have major implications if low or deficient. Because it is generally understood that nutrition is a cornerstone of any sports program, it is vital to ensure proper dietary intakes for both female and male athletes if performance is going to be improved or even sustained (1,2). The combination of poor nutrition or too few calories and inadequate rest can lead to a lack of energy, compromised immune system, and more frequent injuries (3,4).
Now it is important to decipher between eating for aesthetics and eating for performance. When the ultimate goal is speed, power, strength, etc., being very vascular and showing muscular striations is not of great concern. The ultimate requirement is performance. Weight control and strength to weight ratios can be very important, especially in activities that require manipulation of the body, but many athletes get caught up in the struggle of body image and are often torn between perceived societal expectations and their own body image. This is not to be taken as an open invitation to gorging oneself in the name of performance, but many athletes often miss out on their ultimate goal for a couple percent of body fat. Besides, it is impractical and unhealthy to try and stay in the “bodybuilding show” type of condition year round, especially for athletes.
Disordered and poor eating can be associated with a continuum of negative consequences just as proper nutrition can have positive consequences. Intense exercise has been shown to suppress the immune system and create a susceptibility to infection and improper nutrition can compound this affect (3,4,5).
Knowledge and understanding of the role of nutrition in health and performance of athletes has grown considerably over the past couple of decades. The specific role many food components can have on performance and health has become better understood because of new research techniques. The basic concepts of a healthy diet as put forth by the United States Department of Agriculture (6) should be the cornerstone of most sport specific diets. Many of their recommendations are appropriate for athletes. In most cases, if proportions remain the same as the recommendations and the total caloric intake is increased, the nutritional needs of the athlete will be met. Economos, Bortz, and Nelson (1993) stated that “there is no special food that will help elite athletes perform better; the most important aspect of the diet of elite athletes is that it follows the basic guidelines for healthy eating” (p. 382).
The readily available information about fad diets and the pressure to be successful can drive many athletes to try unconventional and often unhealthy dietary habits in an attempt to boost performance. These diets, such as those that leave out entire food types, can lead to impaired nutritional status and poor performance.
Part 1: Determining Caloric Requirements
Maintaining, adding, and losing body mass all in a generic sense depend on the same variable; caloric balance. To gain muscle mass you need to have a positive caloric balance. In basic terms, your caloric intake must exceed your caloric expenditure. If the goal is to lose body fat, a negative caloric balance is required. Just haphazardly eating will most likely lead to disappointing results, no matter what your goals are.
The first step in the process is to determine you caloric expenditure. These simple calculations will give you the starting point for everything else. Located at the end are some examples showing how to calculate.
Determine Your Total Energy Expenditure (TEE)
The Components of Total Energy Expenditure: (7)
* Energy expenditure from physical activity, 15-20%
* Resting energy expenditure (REE) + activity factor (AF) about 75%
* Thermic effect of food (TEF) about 10% or less
STEP 1: Determining your resting energy expenditure (REE)
Use the following equation, The Revised Harris-Benedict Equations for Estimating Resting Energy Expenditure (8), to determine your REE. You will need your height in cm (inches x 2.54) and your weight in kg (pounds / 2.2). If you are less than 10% fat mass, you can go directly into this equation. If you are above 10% fat mass for males and 15% for females, the equation will be more accurate if you take in for this difference. This is your basic calorie expenditure without any exercise.
88.362 + (4.799 x height in cm) + (13.397 x weight in kg) – (5.677 x age)
447.593 + (3.098 x height in cm) + (9.247 x weight in kg) – (4.330 x age)
STEP 2 : Determine the calories you burn during daily living activities
Do not factor in any exercise as that will be calculated in a later step. Find your approximate activity factor in the following table and multiple that times your REE calculated in STEP 1.
Sedentary, largely bedrest
1.2 – 1.3
No planned activity, mostly office work
1.5 – 1.6
Some walking or stair-climbing during the day
1.6 – 1.7
Heavy labor type work
1.9 – 2.1
STEP 3: Determine the energy expenditure during physical activity (EEPA)
Calculating energy expenditure of planned physical activity is done by using the unit of measure MET and body mass. One MET is equivalent to 3.5 mL of oxygen/kg body weight per minute being used for energy production, which is like quietly sitting still. The larger the MET equivalent, the greater the caloric expenditure. To determine EEPA multiply your body-weight in kilograms by time in hours spent exercising and the MET equivalent for that activity. If the exact activity is not found on the table, estimate the MET as compared to similar activities. The table below shows relative MET intensities for various physical activities (9). You have to options here. Either determine the calorie requirement for everyday or you can use the most active day to estimate the entire week depending on your goals. Later you will find tables that help you estimate what your caloric intake should be.
Aerobic dance, low impact
Aerobic dance, high impact
Conditioning exercise, cycling, stationary, light effort
Conditioning exercise, cycling, stationary, vigorous effort
Circuit training, general
Running, 12 min/mile
Running, 10 min/mile
Running, 8.5 min/mile
Running, 7.5 min/mile
Running, 6 min/mile
Sports, basketball, game
Sports, football, competitive
Sports, golf, carrying clubs
Sports, soccer, competitive
Sports, soccer, general
Sports, tennis, doubles
Sports, tennis, singles
Sports, volleyball, competitive, gymnasium
Weightlifting, powerlifting or bodybuilding, vigorous effort
Once you have determined you EEPA, it needs to be added to the result calculated in STEP 2. You have just estimated you total energy expenditure. For help refer to the examples listed below. Remember, your caloric expenditure is not necessarily what your intake should be. This is only a tool for determining your daily intake.
Examples of Case Studies for Determining TEE
A. 20 year old collegiate football player weighing 100 kg and is 182 cm tall involved in vigorous weightlifting for 1 hour four days per week and conditioning 3 days per week during the off-season. This is the result for the two days including both the weightlifting and conditioning.
1. Determine REE
88.362 + (4.799 x 182cm) + (13.397 x 100kg) – (5.677 x 20years) = 2188 calories
2. Multiply REE x AF
2188 x 1.6 (light activity) = 3501 calories
3. Determine EEPA
MET value for vigorous weightlifting 6.0
100 kg x 6.0 METS x 1 hour = 600 calories
MET value for vigorous conditioning 7.0
100 kg x 7.0 METS x 1 hour = 700 calories
4. Add EEPA to REE x AF
For weightlifting and conditioning days
3501 + 600 + 700 = 4801 calories
B. A 19 year old female collegiate soccer player who is 168 cm tall and weighs 70 kg who on a heavy day scrimmages for 1 hour, skill trains for 1 hour, and weightlifts vigorously for 1 hour.
1. Determine REE
447.593 + (3.098 x 168cm) + (9.247 x 70 kg) – (4.330 x 19) = 1533 calories
2. Multiply REE x AF
2705 x 1.6 (light activity) = 2453 calories
3. Determine EEPA
MET value for weightlifting
70 kg x 1 hour x 6.0 METS = 420 calories
MET value for intense scrimmaging
70 kg x 1 hour x 10 METS = 700 calories
MET value for skill training
70 kg x 1 hour x 7.0 METS = 490 calories
4. Add EEPA total to REE x AF
2453 + 420 + 700 + 490 = 4063 calories on heavy training day
Tips for Gaining Lean Mass
1. Keep track of your caloric intake.
2. Eat at least 1.2 g/kg/day of protein but closer to 2.0 g/kg/day may be warranted. We will discuss protein more closely later.
3. Excess calories should come from whole grain carbohydrates and healthy fats.
4. Eat at least 4-6 meals throughout the day to achieve this amount of calories.
5. Eat as soon as possible after training employing superior liquid nutrition.
6. Eating the calories you burn on the heavy exercise days will leave a positive balance on the light days. This is when you will GROW!!! If your heavy day falls on more than 3 days per week, you may need to add additional calories. Use the chart below for some guidelines. Keep track of your gains to see if this is warranted.
Tips for Losing Excess Fat Mass
Shedding excess body fat can be a difficult challenge for athletes. You need to maintain a somewhat high level of performance while doing so. Even while in the off season it is still imperative that you be able to improve skill levels. Following this method will enable this to happen while even possibly gaining some lean muscle mass. Prioritizing needs to be done. Individual athletes need to determine how much time they have to lose the excess mass as compared to how much it will improve performance. This should guide you as to how fast and to how much mass to lose. Once determined, the method and severity of the drop can be decided. Dropping more than 1/2 to 3/4 kg (1 to 1-1/2 pounds) per week can be detrimental to other areas of athletic performance.
Use the following chart to determine your approximate calorie deficit. The low and high range is given. This will require some decision making on your part. If you have only two heavy days, but also have three medium days, you may need to include them in your decision making. Start conservative and adjust as the days go on. You want to lose the extra fat mass with as little loss or no loss of muscle mass.
1. Keep track of your caloric intake.
2. Eat at least 1.2 g/kg/day but closer to 2.0 g/kg/day may be warranted to maintain lean muscle mass.
3. The decrease in calories should come from a combination of carbohydrates and fats. Do not decrease healthy fat consumption below 10-15% of total calories. Maintain a carbohydrate intake at or above 5-7 g/kg/day to maintain energy levels during competition, conditioning, and practice.
4. Eat at least 5-7g/kg/day of whole grain carbohydrates and vegetables.
5. Eat at least 4-6 meals throughout the day to keep you metabolism in high gear.
6. Keep weight training to help preserve lean muscle mass. Also, post exercise caloric expenditure is greater after weight training than after aerobic training.
Tips for Maintenance
Use the following chart to determine the amount of calories that you should eat each day.
Subtract the number of calories based upon the number of heavy training days you participate per week. Be realistic though. If you also participate in a number of less intense training activities you obviously need to subtract a lower amount of calories. Adjust your calories as needed by periodically monitoring total body mass and lean mass percentages.
Part 2: Using the Exchange List to Monitor Calories
The American Diabetes Association has come up with the simplest method to monitor dietary intake. If you most often follow the proper food choices outlined in this manual, keeping track of your calories is very easy if you use the food exchange list for meal planning. It is simple to do. You only need to decide what nutrient profiles you are going to use. I prefer the method of starting with g/kg as compared to straight percentages, which you could also use. For persons eating a large amount of calories, percentages may lead to over or under intake. If you use percentages just be sure to check to see that it falls in line with the g/kg requirements.
1. Determine your total calories by using the given equation.
* For this example we are going to use a 70kg male rugby player trying to gain mass whose calorie requirement is 3,900 calories.
2. Gram and calorie Requirement for Protein (choose the middle value because we will only be calculating the meat or meat substitute protein values).
* 1.8 grams/kg of bodyweight x 70 = approximately 126 grams of protein
* 126 grams protein x 4 calories/gram = 504 calories from protein
3. Gram and calorie Requirement for Carbohydrates
* 9 grams/kg of bodyweight x 70 = approximately 630 grams of carbohydrate
* 630 grams of carbohydrate x 4 = approximately 2,520 calories from carbohydrates
4. Gram and calorie Requirement for fats.
Add the total calories required from carbohydrates and protein.
* 2,520 + 504 = 3,024 calories
Subtract this amount from the total calories to determine the calories from fat.
* 3,900– 3,024 = approximately 876 calories from fat
Divide this number by 9 calories/gram to determine the grams of fat.
* 876 / 9 = approximately 97 grams of fat
***Check to see that this amount is between 10-30% of total calories***
* 876 calories from fat / 3,900 total calories = approximately 22% of calories.
If the calories consumed from fats does not fall in this range, you need to adjust the carbohydrates and protein accordingly. Be sure to keep them within the range though.
Overview of Nutritional Intake
* Protein: 420 calories/ 105 grams (This is the amount tracked, actual intake will likely be 10-15% higher due to vegetable and grain proteins).
* Carbohydrates: 2,520 calories/ 630 grams
* Fats: 960 calories/ 107 grams
As you will read in the next section, an exchange from each group is given a value. These are key to using the exchange list during daily living. As you look through the overview to follow see how it was used to calculate this persons menu plan.
* 105 grams protein / 7grams per exchange = ~ 15 protein exchanges
* 620 grams carbohydrates / 15 grams per exchange = ~ 41 carbohydrate exchanges
* 107 grams fats / 5 grams per exchange = ~ 21 fat exchanges
(Remember to include the fat in some high fat foods)
Meal 1: 6 carbohydrates, 2 proteins, 3 fats
Meal 2: 6 carbohydrates, 2 proteins, 3 fats
Meal 3: 6 carbohydrates, 1.5 proteins, 3 fats
Meal 4: 6 carbohydrates, 3 proteins, 2 fats
Meal 5: 6 carbohydrates, 1.5 proteins, 4 fats
Meal 6: (post w/o) 4 carbohydrates, 2 proteins, 0 fats
Meal 7: 5 carbohydrates, 2 proteins, 4 fats
Meal 8: 2 carbohydrates, 3 proteins, 3 fats
This list is carried throughout the day to help guide decisions about what to eat at each meal. Remember that some of these meals are snacks or meals on the go. Otherwise it would be difficult for this individual to eat this many quality calories. Some planning also needs to be done each day about when and what to eat. Try to spread the meals evenly throughout the day. Meaning that this athlete should eat about every 2 hours, or as some athletes do, nibble food just about constantly.
Overview of Exchange Lists For Meal Planning (ADA, 1995)
*For a complete listing and a workbook, call the American Diabetes Association 800-342-2383 or visitwww.diabetes.org
The main item to remember from each group is the approximate serving size (example: 15 grams of carbohydrates = 1 carbohydrate exchange) and the serving size of some of your favorite items. This will best enable you to use the list during daily living.
Carbohydrate Group (roughly 15 grams)
* Starches (15 grams of carbohydrates, 80 calories)
a. 1 slice bread
b. ½ bagel or hamburger bun
c. 1 small tortilla
d. ½ English muffin
* Cereals and Grains (15 grams carbohydrates, 80 calories)
a. ½ cup bran, wheat, and cooked oat cereals
b. ¼ cup grape-nuts and muesli
c. 1/3 cooked cup rice
* Milk (12 grams carbohydrates, 8 grams protein (counts as a protein also))
a. 1 cup milk
b. 3/4 cup plain yogurt
c. 1 cup fruit flavored yogurt with nonnutritive sweetener
* Vegetables (15 grams carbohydrates, 80 calories)
a. 1/3 cup baked beans
b. ½ cup corn, peas, and various other beans
c. 1 small, 3 oz. Baked potato
* Fruits (15 grams carbohydrates, 60 calories)
a. 1 small apple, orange, nectarine, or pear (4-6 oz.)
b. ½ grapefruit
c. 1 ¼ cup strawberries
d. ½ cup canned fruit in fruit juices or light syrup
e. ½ cup apple, grapefruit, orange, or pineapple juice
Protein Group (roughly 7 grams of protein)
* Very Lean Meat (7 grams protein, <1 gram fat, 35 calories)
a. 1 oz. white meat turkey or chicken no skin
b. 1 oz. Cod, flounder, or haddock fresh or canned
c. 1 oz. Shellfish
d. ¼ cup nonfat or lowfat cottage cheese
e. 2 egg whites
* Lean Meat (7 grams protein, 3 grams fat, 55 calories)
a. 1 oz. Trimmed beef, pork, or lamb sirloin
b. 1 oz. Dark meat turkey or chicken no skin
c. 1 oz. Herring, sardines, or tuna in oil (drained
* Medium-Fat Meat (7 grams protein, 5 grams fat, 75 calories. These choices also include a fat exchange)
a. 1 oz. Of most other beef, pork, or veal
b. 1 oz. Ground turkey or chicken
c. 1 oz. Feta or mozzarella cheese
d. 1 egg
* High-Fat Meat (7 grams protein, 8 grams fat, 100 calories. These choices include 2 fat exchanges)
a. 1 oz. Pork ribs and sausage
b. 1 oz. American, cheddar, jack, swiss cheeses
* Monounsaturated Fats (5 grams, 45 calories)
a. 1/8 avocado
b. 1 tsp. canola, olive, or peanut oil
c. 6 almonds, cashews, peanuts, or pecans
d. 2 tsp. peanut butter
* Polyunsaturated Fats (5 grams, 45 calories)
a. 1 tsp. Margarine (30-50% vegetable oil)
b. 1 tsp. regular mayonnaise
c. 1 tbs. Reduced-fat mayonnaise
d. 1 tsp. regular salad dressing
e. 1 tbs. Reduced-fat salad dressing
* Saturated Fats (5 grams, 45 calories)
a. 1 slice cooked bacon
b. 1 tsp. butter
c. 2 tsp. whipped butter
d. 2 tbs. Regular sour cream or 3 tbs. Reduced-fat sour cream
Part 3: Carbohydrates
Carbohydrates and creatine-phosphate (CP) are the main fuel source used by the body’s cells to replenish adenosine triphosphate (ATP) stores during moderate to intense activities (1, 10, 11, 12). Carbohydrate requirements by athletes can vary depending on the type, intensity, and duration of the exercise event. Berning (2000) stated that:
Sports that use both the anaerobic and aerobic pathways also require a higher glycogen utilization rate and the athlete also runs the risk of running out of fuel before the race or exercise is finished. Sports like basketball, football, soccer, and swimming are good examples of activities where athletes have a higher glycogen utilization rate due to their intermittent bursts of high-intensity sprints and running drills (p. 537).
During exercise, stored muscle glycogen is the first choice for glucose. When muscle glycogen stores become depleted, the body turns to the liver for glycogenolysis and gluconeogenesis to supply carbohydrates to the exercising muscles (Berning, 2000). The reliance of muscle cells upon glycogen as an immediate fuel source is dependent upon the activity’s intensity and duration. These factors can dictate which type of muscle fiber is predominantly used. Rankin (2000) stated:
Muscle glycogen is depleted more rapidly from Type II (fast) than from Type I (slow) muscle fibers during high-intensity exercise. Thus, even when the total depletion of glycogen sampled from a mixture of muscle fibers may be quite modest, extensive glycogen use in some muscle fibers as well as selective depletion of glycogen from specific cellular compartments may precipitate fatigue when bodily stores of carbohydrate are low (p. 1).
CP is the first fuel source for anaerobic activity behind stored ATP (1,10,11,12). Since ATP stores are minimal, CP stores become a limiting factor during anaerobic activity. Gaitanos et al. (1993) found that when subjects performed 10 six-second maximal cycle ergometer sprints with 30-seconds of passive recovery, the fuel source changed from the first to the tenth trial. During the first sprint, glycolysis accounted for 44.1%, CP 49.6%, and ATP 6.3%. The tenth sprint resulted in a shift towards CP as the glycogen stores become depleted. Anaerobic ATP production during the tenth sprint resulted from 80.1% CP and only 16.1% glycolysis with 3.8% of the energy coming directly from stored ATP. The authors also noted a significant drop in total power output from the first to the tenth trial. Biopsies of the vastus lateralis muscle showed a dramatic drop in total ATP production during the late sprints. Estimated ATP production during the first sprint was 89.3+/-13.4 mmol/kg dry weight. The energy production during the tenth sprint was only 31.6+/-14.7 mmol/kg dry weight, a dramatic drop off in energy production.
In a more recent study, Hargreaves et al. (1998) tested subjects during three 30-second maximal cycle ergometer sprints separated by 4-min of passive recovery. Their results were similar to Gaintanos et al. (1993) with respect to the decrease in power production and output during the latter trials as compared to the first.
According to Bangsbo, Graham, and Saltin (1992) and Vandeberghe, Hespel, Eynde, Lysens, and Richter (1995), the availability of muscle glycogen prior to the start of exercise does not affect the initial glycogen utilization and lactate production. It appears that the muscle will use what glycogen is available until the stores become depleted and that there are not any glycogen rationing reactions if the pre-exercise levels are low. CP levels most likely became the limiting factor in the studies performed by Hargreaves et al. (1998) and Gaintanos et al. (1993) because the testing involved passive recovery and not the active recovery that could reduce glycogen stores. These trials are more similar to early in the week conditioning, if the weekend was spent recovering, as well as when players enter the later portions of a game after sitting on the sidelines. Gaintanos et al. (1993) also found that by the ninth sprint the subjects showed a possible partial reliance upon oxidative metabolism to replenish ATP stores. This was hypothesized because of a reduction in pH and muscle lactic acid content during the ninth and tenth sprints. High intensity oxidative metabolism relies mostly upon glucose and therefore carbohydrate stores potentially could have become a limiting factor if the trials were to continue.
Reduced CP and glycogen availability appears to contribute to the decline in anaerobic energy production and exercise performance, especially if the exercise is preceded by moderate-intensity glycogen-depleting exercise (10,11). Similar activities are typical of most intercollegiate sports. According to Hargreaves et al. (1998):
It can be argued, however, that the pre-exercise levels of muscle glycogen in the present (their) study were not limiting at any stage and that a greater degree of glycogen depletion is required before glycogenolysis and performance are affected during high-intensity exercise (p. 1689).
Another method to create low pre-exercise glycogen stores is for athletes to eat low levels of dietary carbohydrates. Carbohydrate loading is a term often reserved for long endurance sports but it may impact performance during sports such as strongmen competitions, fitness competitions, rugby, basketball, football, and military training. Hawley et al. (1997) found that carbohydrate loading did not improve performance during either high-intensity exercise lasting less than twenty minutes or moderate-intensity exercise lasting 60-90 minutes in duration. Mitchell, DiLauro, Pizza, and Cavender (1997) found carbohydrate ingestion prior to resistance training to have no impact on performance. During these studies, muscle glycogen stores were not reduced to below normal levels and thus glycogen failed to become the limiting factor. Pizza, F., Flynn, M., Duscha, B., Holden, J., and Kubitz, E. (1995) and Tarnopolsky, M., Atkinson, S., Phillips, S., and MacDougall, J. (1995) both concluded that when high-intensity exercise to exhaustion, 75% VO2max and 85% VO2max respectively, is preceded by sub-maximal glycogen depleting exercise, a high carbohydrate loading diet did improve performance. Most athletic events involve intermittent sprints dispersed between periods of moderate-intensity exercise that deplete glycogen stores. Thus having higher levels of stored glycogen for pre-exercise and training can improve performance when compared to the same activities being performed with low starting glycogen levels.
Athletes participating in soccer were monitored to find the implications of low and high carbohydrate diets on performance by Balsom, Wood, Olsson, and Ekblom (1999). They tested six male soccer athletes during four 90-minute four per side soccer games who had eaten either a high 65% carbohydrate diet or a low 30% carbohydrate diet. Statistical analysis of the results showed approximately a 33% reduction in high-intensity exercise during game play when following the low carbohydrate diet. A reduction of involvement in the high-intensity action within a game may have implications to the total number of scoring and defending opportunities within the contest.
Carbohydrate restriction causing low muscle glycogen may not only have negative implications on game and practice performance, but strength training can be impaired. To successfully compete in today’s environment, resistive training is a must. Whether from low dietary intake or from prior activities depleting the carbohydrate stores, low muscular glycogen has been shown to reduce performance during maximal repetition sets of resistance training. Leveritt and Abernethy (1999) tested one female and five male subjects performing 3 sets of maximal squat repetitions at a level 80% of their estimated one repetition maximum. Each subject was tested following both two days of a high carbohydrate diet and two days of a low carbohydrate diet preceded by 60-minutes of cycling at 75% peak oxygen consumption while exercising on a cycle ergometer followed by four one-minute bouts at 100%. Results showed a significant reduction in total squat repetitions. Performance of this nature can limit the strength improvements of all individuals participating in these types of activities. Of particular importance here is contact sports and strongmen competitions. When improvement in the weightroom is a must, it appears that a low carbohydrate diet is not the ideal. Imagine the implications if a strongmen competitor was never fully able to effectively push himself past his or her past limitations.
It has been found that the rate of glycogenolysis during resistive training is relative to the intensity being performed (22). Using muscle biopsies of the vastus lateralis muscle, the researchers found that working to exhaustion at 70% one repetition maximum leg extension produced approximately double the rate of glycogenolysis compared to performing at 35% one repetition maximum to exhaustion. “These findings imply that the total amount of muscle glycogenolysis was dependent on the magnitude of muscle force development and that the rate of glycogenolysis was dependent on exercise intensity” (p. 1703). This means that the greater the amount of work performed during resistance training, the greater the amount of glycogen that will be used. Thus carbohydrate restriction and low muscular glycogen levels can impair progress during high intensity weight training. Glycogen can easily become the limiting factor in strength training, especially if it is combined with other modes of physical activities.
With this information in mind, carbohydrates should represent approximately 50% to 70% of calories, or 7-10 grams of carbohydrates per kilogram of bodyweight per day (g/kg/day) for training and performing athletes (1, 13, 22). This will seem like overkill to many which are involved in aesthetic diets, and for bodybuilders it may very well be. These individuals are primary concerned with negating the conversion of glucose to both glycerol and fatty acids to form triacyglycerols in adipose tissue. The adding of adipose tissue mass seems much more reliant upon the reduction of lypolysis with the use of glucose instead for energy (23). But as stated before, glucose is the preferred nutrient for these athletes to perform best anyway. Because insulin has a dramatic affect in increasing liver fatty acid synthesis in the liver through acetyl coA carboxylase and tryacyglycerol synthesis in adipose tissue through lipoprotein lipase, the best preventative measure is to control the extent of the insulin released from the pancreatic beta cells. The best method to avoid high insulin levels is to eat small frequent meals that are composed mostly of complex carbohydrates such as pasta, rice, whole oats, lentils, and whole grain breads (1, 24, 25). These food products are generally higher in fiber, complexity, vitamins, and minerals. This not only allows for more sustained energy, but also is more heart healthy.
Nutrient intake also needs to match the activity level. For multiple sprint sport athletes, strongmen competitiors, lumberjack competitors, and military personell to succeed, a carbohydrate level this high is required. Certain amino acids and glycerol can be metabolized into carbohydrate constituents and thus be used for energy. Many of the Krebs cycle intermediates can be used for gluconeogenesis. When trying to improve performance in either strength or endurance, this is not a favorable situation for two very important reasons. When the liver reverses glycolysis, not only is the body using important resources, but it happens at the expense of other anabolic reactions. This means that insufficient carbohydrate intake can potentially limit the extent of protein synthesis by causing both stored and free amino acids to be used for gluconeogenesis and also for current protein synthesis to be slowed or halted. The same situation goes for lipids and their glycerol tale in gluconeogenesis and subsequent hormone production.
Now 7-10 grams is a relatively broad range. Both the sport and personal characteristics can dictate to which end individuals will fall. In general, the more movement performed, the more carbohydrates required in the diet.
All Carbs are Not Equal
The following chart is based modestly upon the glycemic index, and thus complexity, and vitamin & mineral content.
Whole oats (oatmeal)
Non-whole wheat breads
Whole wheat cereal
Whole wheat bread
Whole wheat pasta
High-fat & sugar muffins
Lentils White potatoes (with skin)
In next month’s segment, I will cover at least protein, fats, and hydration. If I am notified of any additional information on this subject or topics that people are interested in, I will possibly include them in the next article, or in future issues, so send requests to [email protected].
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