Download Semester 3, Grading Period 1 Study Guide File

STRENGTH AND CONDITIONING
SEMESTER 3, GRADING PERIOD 1
STUDY GUIDE
NUTRITIONAL FACTORS OF MACRONUTRIENTS IN PERFORMANCE
1. MACRONUTRIENTS = Nutrients that are required in significant amounts in the diet. Three
important classes of macronutrients are protein, carbohydrates, and lipids (fats and related
compounds).
2. PROTEIN = Relatively complex molecules that have enzymatic and structural functions and are
important in a variety of biosynthetic and bioenergetic reactions
A. Amino acids - These are the basic units of protein structure. Synthesis of proteins in humans
requires approximately 22 distinct amino acids. Nine of these are essential amino acids in
adults: the body cannot synthesize them but must obtain them from plant or animal proteins
ingested in the diet. The remaining nonessential amino acids can, of course, be obtained from
ingested proteins, but can also be synthesized from other substances (such as carbohydrates),
as long as there is an adequate source of nitrogen in the body (such as other amino acids).
Dietary proteins that contain very low amounts of one or more of the essential amino acids are
known as incomplete proteins. Incomplete proteins are generally of plant origin. Dietary
proteins that contain all the amino acids needed (essential and nonessential) for the synthesis
of human tissue protein have a high biological value and are known as complete proteins.
These proteins are generally found in animal sources and products.
B. Protein synthesis - The combining of amino acids to make proteins. Very low dietary intake
of an essential amino acid reduces the rate of protein synthesis and impairs the use of other
amino acids for protein synthesis.
C. Protein requirements - During cell turnover - the constant breakdown and regeneration of cells
- the immediate supplier of amino acids is the body’s free acid pool. The pool is replenished
from dietary protein digestion, as well as the amino acids released from tissue turnover.
Substantially more protein is turned over daily than is ordinarily consumed, indicating that
amino acids are recycled. This process is not completely efficient, however, so dietary
amino acid intake is required to replace losses. When estimating the protein requirements for
individuals, two key factors, caloric intake and biological value of the protein, must be
considered. Assuming adequate caloric intake and two thirds or more of the protein from
animal sources, the recommended dietary allowance (RDA) for protein for adults is 0.8 g per
kilogram of body weight for both men and women.
D. Requirements for athletes - Beyond the maintenance requirement of protein previously
described, athletes’ protein requirements are increased by training. Both aerobic endurance
training and strength training can increase protein need, although the exact mechanisms are
unclear and may be different. For aerobic endurance athletes, the underlying mechanisms
could include tissue repair and the use of the branched-chain amino acids for auxiliary fuel,
whereas for strength and power athletes, the mechanisms are probably tissue repair and the
maintenance of a positive nitrogen balance so that the hypertrophic stimulus is maximized.
Research indicates that the protein requirement of aerobic endurance athletes is slightly over
0.8 g/kg of body weight and can reach 1.4 g/kg of body weight. It also shows that strength
straining can increase requirements to as high as 1.7 g/kg of body weight. Because most
athletes don’t fall neatly into one category, a general recommendation of 1.5 to 2.0 g/kg of
body weight ensures adequate protein intake, assuming adequate caloric intake and a diet with
at least 65% of the protein of high biological value.
3. CARBOHYDRATES = Compounds of carbon, hydrogen, and oxygen.
A. Function - The primary role of carbohydrates in human physiology is energy provision.
Numerous studies have documented an ergogenic effect of carbohydrate intake and elevated
muscle glycogen concentration on aerobic endurance performance, work output, and highintensity, intermittent activity. Additionally, muscle glycogen concentration may be
beneficial to high-intensity exercise of short duration.
B. Structures and sources - Carbohydrates can be classified into three groups according to the
number of sugar units they contain: monosaccharides (one), disaccharides (two), and
polysaccharides (thousands, also known as complex carbohydrates).
Glycogen is found in small amounts in human and animal tissue as a temporary source of
stored energy. When glucose enters the muscles and liver, it is not metabolized for energy, it
is synthesized to form glycogen. Two thirds of the glycogen in the body is stored in skeletal
muscle; the remaining third is stored in the liver.
Traditionally, breads, cereals, pasta, fruits, and starchy vegetables are promoted to athletes as
ideal sources of carbohydrates. It should be understood, however, that all types of dietary
carbohydrate - sugars as well as starches - are effective in supplying the athlete with glucose
and glycogen. Consumption of a mix of sugars and starches is desirable.
The glycemic index (GI) classifies a food by how high and how long it raises blood glucose.
Foods that are digested quickly and rapidly raise blood glucose (and insulin) have a high GI.
Carrots are one such food. Foods that take longer to digest and therefore slowly increase
blood glucose (and therefore stimulate less insulin) have a low GI. Lentils are an example of
these. Many factors affect the GI of a food: cooking, processing, eating the food as part of a
meal, eating a different amount, and eating at a different time of day all affect the GI of a food
in an individual. In fact, what was eaten the day before can have a latent effect on the
glycemic response of a food. Thus, although the GI is of interest and can be used for a
general understanding of how foods behave when consumed, it is far from an exact science.
To apply the GI to guide food choices use the following guidelines: If the goal is to quickly
replenish glucose and glycogen, foods that rapidly appear as glucose in the blood are
desirable. On the other hand, low GI foods may spare carbohydrate by minimizing insulin
secretion and increasing fatty acid levels in the blood.
C. Carbohydrate requirements - Roughly 50 to 100 g of carbohydrate per day is needed to
prevent ketosis (high levels of ketones in the bloodstream). Beyond that need, carbohydrates
provide fuel for energy. American health authorities generally recommend consuming at least
55% of total calories from carbohydrate.
Because of the relationship of carbohydrate intake to muscle and liver glycogen stores and to
the protein-sparing effect of high concentrations of muscle glycogen, a high-carbohydrate diet
is commonly recommended for all athletes. One important factor to consider when
determining recommendations for carbohydrate intake is the training program. Aerobic
endurance athletes who train for long durations (90 minutes or more daily) should replenish
glycogen levels by consuming maximal levels of carbohydrate, approximately 8 to 10 g/kg of
body weight. This is equivalent to 600 to 750 g of carbohydrate per day for an athlete
weighing 165 lb. This level has been shown to adequately restore skeletal glycogen within 24
hours. Athletes who benefit from this level of carbohydrate intake include those engaged in
continuous, aerobic activity for more than an hour on most days, such as distance runners,
road cyclists, triathletes, and cross-country skiers. Research has shown that athletes engaged
in high-intensity, intermittent activities, such as soccer players, also benefit from high-
carbohydrate diets. However, the majority of power and sprint athletes do not train
aerobically for more than an hour each day. Research on the carbohydrate needs of these
athletes - such as football players, sprinters, basketball players, wrestlers, volleyball players,
and so on - is limited. Carbohydrate intake and muscle glycogen levels seem to have much
less impact, if any, on strength performance. Intake of approximately half of that
recommended for aerobic endurance athletes appears adequate to support training and
performance of strength, sprint, and skill athletes, and thus an intake of 5 to 6 g/kg per day is
reasonable.
4. LIPIDS = Substance that can be extracted from biological material with such organic solvents as
ether, chloroform, and acetone and that are relatively insoluble in water. Lipids include both solid
fats and liquid oils.
A. Function - Lipids have the following functions: sources of energy, structural components of
cell membranes and the myelin sheath on neurons, transporters of lipid-soluble vitamins, and
in the synthesis of cholesterol and production of associated steroid hormones.
B. Fatty acids - The simplest lipids may be saturated or unsaturated. Saturated fatty acids have
all single bonds between carbons. Unsaturated fatty acids contain one (monounsaturated) or
more (polyunsaturated) double bonds between carbon atoms. Generally speaking, saturated
fatty acids are more unhealthy than unsaturated fatty acids.
C. Lipid requirements - The recommendation for the general public from health organizations
such as the American Heart association is that fat constitute 30% or less of the total calories
consumed. 20% of the total calories come from monounsaturated or polyunsaturated sources
and 10% from saturated fats. This recommendation is given primarily to reduce the incidence
of cardiovascular disease. Fat guidelines for individual athletes, however, may be higher than
standard “heart healthy” guidelines. Research shows that during periods of heavy endurance
training, increasing dietary fat as high as 50% of calories does not negatively affect plasma
lipids. Indeed, fat intakes greater than 30% are common in elite athletes. In light of the
differing metabolism of fats in actual people, the Subcommittee on Nutrition of the United
Nations recommends an upper limit for fat intake of 35% of total calories for active people.
Additionally, diets extremely low in fat (less than 15% of total calories) may decrease
testosterone production, thus decreasing metabolism and muscle development.
D. Fat and performance - Both intramuscular and circulating fatty acids are potential energy
sources during exercise. It appears that intramuscular fatty acids are relatively more
important during activity, and circulating fatty acids (from adipose tissue or diet) are more
important during recovery. Compared with the limited capacity of the body to store
carbohydrate, fat stores are large and represent a vast source of fuel for exercise. At rest and
during low-intensity exercise, a high percentage of the energy produced is derived from fatty
acid oxidation. With increasing exercise intensities (over 70-80% VO2 max), however, there
is a gradual shift from fat to carbohydrate as the preferred source of fuel.