Module 10 mcc sports nutrition credit course - body composition and sports performance
MODULE 10 – BODY COMPOSITIONAND SPORTS.
REASONS FOR ASSESSMENTSProvides a starting point to base current and future decisions about weight loss and weight gainProvides realistic goals about how to best achieve an “ideal” balance between the body’s fat and nonfat compartmentsRelates to general health status, thus playing an important role in establishing short and long-term health and fitness goals for all individuals
A) METHODS OF ASSESSMENT Direct Assessment of Body Composition: • One technique involves dissolving the body in a chemical solution to determine the fat and fat-free components of the mixture. • The other technique involves the physical dissection of fat, fat-free adipose tissue, muscle, and bone. These techniques are : 1. time consuming and tedious, 2. require specialized laboratory equipment, and 3. involve ethical questions and legal problems in obtaining cadavers for research purposes.
Indirect Assessment of Body Composition 1. Hydrostatic weighing 2. Skinfold thickness 3. Girth measurements 4. Bioelectrical impedance analysis 5. Near-infrared interactance 6. CT or MRI 7. Dual-energy x-ray absorptiometry 8. BOD POD using air plethysmography
Hydrostatic Weighing• Involves the application of Archimedes’ principle• Because an object’s loss of weight in water equals the weight of the volume of water it displaces, specific gravity refers to the ratio of the weight of an object in air divided by its loss of weight in water.• Dividing a person’s body mass by body volume yields body density (Density = Mass Volume) and, from this, an estimate of percentage body fat.• Involves immersion in water
Skinfold MeasurementsThe rationale for using skinfolds to estimate body fat comes from the relationships among three factors.1. Fat in the adipose tissue deposits directly beneath the skin (subcutaneous fat)2. Internal fat3. Whole-body densityThe most common anatomic locations for skinfold measurement include the triceps, subscapular, suprailiac, abdominal, and upper thigh sites
Girth MeasurementsInvolves the application of a linen or plastic measuring tape lightly to the skin surface so the tape remains taut but not tight.Along with predicting percent body fat, girths can analyze patterns of body fat distribution, including changes in fat distribution during weight loss.Measures of waist girth and the ratio of waist girth to hip girth provide an important indication of disease risk.
Bioelectrical Impedance AnalysisA painless, localized electric current is introduced, and the impedance (resistance) to current flow is determined between the source and detector electrodes.Computes percent body fat from the Siri equation or another similar density conversion equation
CT and MRIComputed tomography (CT) and magnetic resonance imaging (MRI) produce images of body segments.CT scans can evaluate the relationship between simple anthropometric measures (skinfolds and girths) at the abdominal region and total adipose tissue volume.MRI effectively quantifies total and subcutaneous adipose tissue in individuals of varying degrees of body fatness.
BOD PODUses air displacement plethysmography to estimate body volumeBody density computes as body mass (measured in air) body volume (measured in BOD POD).The Siri equation converts body density to percent body fat.
b) Optimal weight and body compositionin athletes.
The reference man is taller and heavier, his skeletonweighs more, and he has a larger muscle mass and lowertotal fat content than the reference woman.Reference man:Fat 15% of total body massReference woman:Fat 27% of total body mass
Essential and Storage Fat • Essential fat consists of the fat stored in the marrow of bones, heart, lungs, liver, spleen, kidneys, intestines, muscles, and lipid-rich tissues of the central nervous system. • Normal physiologic functioning requires this fat. • Storage fat depot consists of fat accumulation in adipose tissue. • Reference man: approximately 12% storage fat • Reference woman: approximately 15% storage fat
Fat-Free Body Mass and Lean Body Mass • Lean body mass (LBM) contains a small percentage of essential fat stores equivalent to approximately 3% of body mass. • Fat-free body mass (FFM) represents the body devoid of all extractable fat. • In normally hydrated, healthy adults, FFM and LBM differ only in the “essential” lipid-rich stores in bone marrow, brain, spinal cord, and internal organs.
MEN• To calculate the lower fat limit in men (i.e., the LBM), subtract storage fat from body mass.For the reference man:• LBM (61.7 kg) includes approximately 3% (2.1 kg) essential body fat.• Encroachment into this reserve may impair normal physiologic function and capacity for vigorous exercise.
WOMEN• The lower limit for the reference woman includes about 12% essential fat.• Equals 48.5 kg for the reference woman.• Generally, body fat percentages for the leanest women in the population do not fall below 10–12% of body mass.• This value probably represents the lower limit of fatness for most women in good health.
(c) Weight gain and weight loss intraining and competition
‘Making weight’ is the practice used by weight-class athletes to lose weight in order to compete. In weight-class sports - boxing, lightweight, rowing,weightlifting, wrestling, judo and other combat, sports, athletes must meet a certain weight classification to competeThere are two types of weight cutting:1. One method is to lose weight in the form of fat and muscle in the weeks prior to an event;2. Other is to lose weight in the form of water in the final days before competition.
HOW DO ATHLETES MAKE WEIGHT?If an athlete needs to ‘make weight’ for a competition, the mostcommon weight reduction strategy is rapid weight loss (within the week before the competition).Weight loss methods are varied and include severedieting or starvation, fluid restriction, passive (sauna) or active(exercise in “sweat suits) dehydration, and the use of diuretics,laxatives, or self-induced vomiting.These rapid weight-making techniques reduce weight,principally by decreasing body fluids, food in thegastrointestinal tract and muscle energy stores
IMPLICATIONS OF RAPID WEIGHT LOSS Two major health risks: 1. Malnutrition 2. Dehydration. Dehydration - results in impairments in performance and proper body function. Dehydration is the most acute and the most dangerous. Malnutrition is caused by inadequate intake of nutrients.
1) Rapid weight loss by fluid restriction leads to dehydration—not fat loss.2) Fluid loss of as little as• 1% of body weight (0.7 kg in a 70 kg person) has shown to decrease endurance performance• 2% to 4% - result in reduced (VO2max).• Shown to impair endurance performance by 20%.• Yet, in boxing, a 2% rapid weight loss strategy is common3) As fluid reduction increases, so too do the dangerous consequences caused by the inability of the body to effectively regulate temperature - heat injury, including muscle cramps, heat exhaustion, and heat stroke
SHORT TERM CONSEQUENCES• Mood swings, lack of energy and lack of motivation, which can all contribute to• Impairments in performance athlete will have less energy, slowed metabolism, loss of muscle mass, strength, power and a reduced endurance capacity leading to underperformance• Additionally, there is an increased risk of mental and physical exhaustion. The most extreme consequence of rapid excessive weight loss (of greater than 10%) may result in collapse and possible death. In 1997, three collegiate wrestlers died, while attempting rapid weight lossfor their weight-class certifications
LONG TERM CONSEQUENCES• Eating disorder, such as anorexia nervosa or bulimia nervosa• Vitamin and Mineral deficiencies• Changes to hormonal and metabolic function. The levels of body fat considered to be minimal levels compatible with good health are 5% for males and 12% for females (Lohman,1992). However, the ranges of body fat for athletes vary by sport and by gender within a sport.
BODY FAT LEVELSMales: 8–12% for malesFemales: 16–20% for females.
WEIGHT GAINStrength and power are important traits in many sports.• Increasing muscle mass represents an important part of their athletic development.• There are three key components or ‘ingredients’ that are considered essential if an athlete is to achieve their ‘bulking up’ goals:1. A well designed resistance training program2. A high-energy diet that provides adequate protein3. Consistency
1) HIGH ENERGY DIETMuscles need energy to grow, so it makes sense that anincrease in overall dietary intake is required.The main focus - high energy, nutrient dense foodsThe need to increase total energy intake is not seen as anexcuse to fill up on energy dense, nutrient poor foods (e.g.takeways, ‘junk food’). This will increase the likelihood ofgaining fat rather than muscle mass.
MISCONCEPTION - HIGH PROTEIN DIET IS NECESSARY COMMON among athletes is that the best way to build muscle or “bulk up” is to eat a high-protein diet. Adequate protein intake is essential when you are increasing muscle mass, but most of the energy needed to fuel muscle growth comes from an adequate calorie intake from carbohydrates and fats
2) TRAINING AND TIMING• To optimise muscle size and strength, it is essential athletes support each training session with nutrients required to support muscle growth.• Consume a carbohydrate-rich snack that also provides 10- 20 grams of protein within 30 minutes of finishing training• Carbohydrate will help to re-fuel the muscle, reduce muscle breakdown• Protein will support the growth of new muscle tissue
3) CONSISTENCY • Muscle development takes time and a commitment to a well structured training and meal plan is essential if the athlete is to achieve their strength gain goals
ACTIVITYSample Menu #1:Breakfast: Oatmeal and fresh fruit.Snack: Yogurt and a energy bar. , Snack: Pretzels.Lunch: 1 Deli sandwiches (Turkey), and an apple.Snack: 1 Peanut butter and jelly sandwich, and milk.Dinner: Grilled chicken and steamed vegetables.Sample Menu #2:Breakfast: Cheerios, banana, and milk.Snack: Graham crackers and milk. , Snack: Frozen yogurt.Lunch: 1 slice of cheese pizza, salad, and fruit juice.Snack: 1 English muffin w/jelly.Dinner: Pasta w/marinara sauce, a vegetable, and milk.
HANDY HINTS FOR WEIGHT GAIN• Athletes should plan in advance and have snacks on hand in gear bags, cars etc.• Athletes should consume a certain amount of their calories from liquid•In order to gain weight this increased food intake should be carried out consistently.• Athletes need to eat, drink, rest and carry out relevant training,.• A specific hypertrophy (muscle building) weight-training programme should be incorporated..