Sports Nutrition Flashcards
1
Q
Aerobic Exercise
A
- Working large muscle groups
- Extended period of time (endurance)
- Activities of low-moderate intensity: walking, rowing, joggin, swimming, etc.
2
Q
What is used for energy in Aerobic exercise?
A
Oxygen used for ATP production
3
Q
Anaerobic Exercise
A
- Higher intensity
- Provides energy for short bursts of activity
- Dependent on good carbohydrate supply
- Duration that activity can be sustained is limited
- Examples: power lifting, sprinting
4
Q
Fuel used during Aerobic Exercise
A
- Oxygen required!
- Muscle glycogen –> glucose. Abundant supply of ATP produced
- Stored triglycerides –> fatty acids. Unlimited supply of ATP produced. Requires some CHO for oxidation.
- Protein (muscles) –> amino acids. Not preferred energy source. Used with longer duration as CHO stores decrease. Used in athletes who fail to meet kcal and CHO needs.
5
Q
Glycogen Depletion
A
- Other substances must fuel the Kreb’s cycle
- Protein –> Energy.
- Limited ATP production from fat
- Slow process, keeps you alive but not good for athletic performance.
6
Q
Which type of diet produces the maximum endurance time? Which produces the shortest?
A
High-carbohydrate diet = longest
High-fat diet = shortest
7
Q
Factors that contribute to decline in aerobic performance
A
- Glycogen depletion = #1 limiting factor.
~ Energy production from protein is slow
~ Fat cannot be fully oxidized in the absence of CHO - Dehydration
8
Q
Fuels during Anaerobic Exercise
A
- ATP: muscle store lasts for only a few seconds
- Phosphocreatine System: regenerates ATP in muscle, lasts 5x longer than ATP alone
- Lactic Acid System (anaerobic glycolysis): glucose to lactic acid, generates small amounts of ATP quickly, glucose used 18x faster than under aerobic conditions, CHO supply is important.
9
Q
VO2 Max
A
- Maximum amount of oxygen an individual can take up at maximum intensity
- Genetics = main determinant
10
Q
When do blood lactic acid levels begin to rise?
A
As intensity approaches 60-80% VO2 Max
11
Q
Type 1 Muscle Fibers
A
- Slow Twitch
- Oxidative fibers (aerobic)
- High myoglobin content
- Slow contraction speed
- Moderate to high glycogen storage
- High triglyceride storage
- Good energy supply
12
Q
Type IIA Muscle Fibers
A
- Fast Twitch
- Oxidative
- Glycolytic (anaerobic)
- Fast contraction speed
- Moderate to high glycogen storage
- Moderate triglyceride storage
- Moderate energy supply
13
Q
Type IIB Muscle Fibers
A
- Pure Fast Twitch
- Glycolytic (anaerobic)
- White fibers (lack mitochondria)
- Low oxidative capacity
- Fast contraction speed
- Glycogen storage moderate to high
- Triglyceride storage low
- Total energy supply poor
14
Q
How many carbohydrates should athletes consume?
A
- High carbohydrate
- 60-70% of total calories
- 700g (15g = 1 serving)
15
Q
What happens if an athlete does not consume enough carbohydrates?
A
- fail to maximize glycogen stores
- general complaints about low energy levels
- fatigue
- impaired endurance
16
Q
Risk factors contributing to low carbohydrate diet?
A
- high protein diet
- eating disorders
- athletes trying to make weight
17
Q
What happens to CHO when consumed in excess?
A
- CHO becomes fat and is stored
- Available as an energy source
- Fat never gets back to glucose!
18
Q
Glycemic Index of Food
A
- Rate & degree of rise in blood glucose
- High glycemic index: load glycogen stores, consume these foods after exercise, insulin response directs glucose to glycogen
- Lower glycemic index: carbohydrate source, 2-3hrs prior to exercise, blunts insulin response (increase use of fat as energy source, spares glycogen, prevents rebound hypoglycemia)
19
Q
Protein
A
- Athletes needs are greater than RDA
- Both endurance and strength training athletes need more protein than RDA
- With increase in kcal intake usually consumed by athletes, needs are usually met or exceeded with standard diets.
- Scientific evidence is lacking to support intakes greater than 2.0g/kg in strength training
- Many athletes consume excess protein
- Requires adequate kcal/CHO
20
Q
Protein Supplements
A
- Provide high quality protein in a low fat mixture
- Evidence lacking to show that protein is absorbed better from protein or amino acid supplements
- No evidence to show that supplements have a greater impact than comparable amounts of dietary protein on muscle development, strength, and endurance
21
Q
Excess Protein & Amino Acid Supplements
A
- Diets can be too low in CHO: decreased energy, decreased ATP for protein synthesis, muscle breakdown to produce energy
- Increased workload to kidney: dehydration, transient rise in ammonia levels
- Amino acid imbalances
- Higher osmolar load/lactose intolerance: cramping and diarrhea
22
Q
Risk Groups for Calorie Deficits
A
- Failure to maintain weight
- Eating disorders
- Making weight
- High energy demand sports/ heavy training
23
Q
Antioxidants
A
- Vitamins A (beta-carotene), C and E
- Exercise increases oxidation and therefore oxidative stress; muscle damage and inflammation, may help in recovery phase
- Should be able to get from diet
- No contraindications to moderate supplementation
24
Q
Vitamin B6 (pyridoxine)
A
- Protein synthesis
- Transamination & deamination
- Touted for use with body builders
- Insufficient evidence to support use
- Large doses (10x RDA) can lead to toxicity
- B vitamins in general important in energy transfer and ATP production
- Thiamine rapidly depleted with alcohol
25
Q
Calcium
A
- Low intake of milk and other dairy products
- Milk replaced with water, sports drinks, low calorie soft drinks
- Mucus production (if low calcium)
- Risks: early osteoporosis (amenorrhea), increased risk of fractures
- Correct dietary deficiencies or OTC supplementation prn to counteract low calcium
26
Q
Iron
A
- Increased need for oxygen delivery
- Myoglobin synthesis
- Deficiency Risk: female, low intake, calorie restriction, male/female vegetarian (lactovegetarian)
- Potential Toxicity: male athletes consuming large amounts of iron rich protein sources, protein supplements with extra iron, OTC supplements containing iron
27
Q
Factors affecting fluid loss
A
- Urine
- High protein diets
- High sodium intake - Skin and lungs
- vigorous exercise
- high temperature: 13% for every 5 degree F rise over 75
- low or high humidity
- high altitude
28
Q
Monitoring Hydration and Fluid Status
A
- Thirst is not a good indicator in an athlete
- Athletes replace only 2/3 of loss ad lib
- Exercise blunts thirst mechanism
- Thirsty = dehydrated - Monitor weight
- Pre and post training
- Maximum weight loss should not exceed 3%
- Replace water based on fluid loss: 4lb weight loss, 8 cups of fluid = 64oz
29
Q
Fluid Replacement Recommendations Before Exercise
A
- 16-20oz two hours prior to exercise
- 16oz cold fluid just prior to exercise
- Avoid caffeine and alcohol (diuretics)
- Water usually fine
- Endurance athletes may benefit from sports drinks or diluted fruit juice
- Sports drinks may be more appealing than water
30
Q
Fluid Replacement Recommendations During Training and Competition
A
- 4-6oz every 10-15 minutes
- Small frequent drinks to avoid bloating: stomach can empty up to 800cc/hr = 3.5cups
- Water is great
- Sports drinks or diluted fruit juice may be beneficial for events >60-90 minutes
31
Q
Fluid Replacement Recommendations After Exercise
A
- 2 cups for every pound loss or 16oz fluid
32
Q
Benefits of Sports Drinks
A
- fluid
- glucose and other carbohydrates (6% CHO)
- sodium, potassium, other electrolytes
- may be beneficial for activities of >60 minutes
- considered preferable/essential for rigorous events of long duration unless glucose and electrolytes replaced by other sources
- may be preferred to plain water –> drink more
- can contribute to dental carries
- sports drinks are NOT synonymous with enhanced water or energy drinks
33
Q
Acute Dehydration
A
- > 1% loss in body weight
- Large ECF losses of both sodium and water
- 6% loss of body weight is life-threatening
34
Q
Chronic Dehydration
A
- > 1% loss of body weight
- Loss of both ECF and ICF
- Can see losses up to 10% of body weight
35
Q
Signs & Symptoms of Dehydration
A
- Increased concentration of electrolytes in ECF/ICF
- muscle cramps
- postural hypotension
- tachycardia
- decreased urine output
36
Q
Dehydration Risk
A
- athletes practicing aggressive calorie restriction and dehydration practices to make weight
- anorexia nervosa and bulimia
- inadequate fluid replacement
- rigorous training hot/humid climates
37
Q
Temperature Regulation
A
- Factors impairing heat loss
- too many clothes, protective gear
- too humid of a climate to allow evaporation
- inadequate water supply to sweat glands
- high body fat - Risk for heat exhaustion
- poorly conditioned athletes
- early training for fall sports in heat/humidity
- dehydration
38
Q
Heat Acclimation
A
- Expansion of plasma volume at rest
- Maintenance of plasma volume during exercise
- Increased capacity to produce sweat
- Increased cooling: smaller rise in core temperature, risk of dehydration due to fluid loss in sweat
- No adaptation to dehydration
39
Q
Heat Cramps
A
- Usually associated with drop in serum sodium and chloride
- Most common in individuals exercising long periods in hot climates, replacing only water
- Tonic contractions of voluntary muscles, including abdomen
- Treatment/Prevention: 0.1% oral saline (sports drinks)
40
Q
Heat Exhaustion
A
- Causes:
- sodium depletion, impaired acclimation, plain water replacement, dehydration - Signs & Symptoms:
- profuse sweating, headache, nausea and vomiting, dizziness, visual disturbances, extreme fatigue, weak/rapid pulse - Treatment:
- stop exercise, remove clothing, move to cool place, sponge with cool water, oral fluid replacement based on weight loss (1L/hr), correct electrolyte imbalance
41
Q
Severe Heat Exhaustion
A
- Signs & Symptoms
- hypovolemia, hypotension, hyperventilation, tachycardia, decreased urine output, decreased sweating - Treatment:
- emergency medical management, normal saline, 1/2NS, 5% dextrose
42
Q
Heat Stroke
A
- Causes:
- excess heat production secondary to exertion, impaired dissipation of environmental heat, use of antihistamines - Symptoms:
- headaches, hot/cold flashes, weakness, lack of sweat, hot/dry skin, visual problems/deafness, hallucinations, nervousness, unsteady walking, core temp 107 - multisystem organ failure - Treatment:
- Field Management: stop exercise, remove clothing, move to cool environment, sponge with cool water, fan
- Emergency Medical Intervention: IV fluid and electrolyte replacement, monitoring core temperature, organ function, fluid and electrolyte status
43
Q
Actions of Anabolic Steroids
A
- increase rate of gain in lean body mass
- increase muscle size, mass
- increase muscle strength
- androgenic = increase in masculinization
44
Q
SIde Effects of Anabolic Steroids
A
- Musculoskeletal:
- decreased strength & elastic compliance of tissue
- premature cessation of linear growth, premature closure of epiphyses - Cardiovascular:
- increase LDL, cholesterol; decreased HDL
- increased platelet aggregation
- hypertension
- MI and CVA - Hepatocellular dysfunction
- Depressed immune function
- HIV/hepatitis transmission
- Severe acne
45
Q
Side Effects of Anabolic Steroids (continued)
A
- Males
- infertility, oligospermia
- decreased testicular size
- gynecomastia
- prostate cancer - Females
- decreased LH, FSH, estrogens, progesterone
- virilization: voice change, facial hair, menstrual irregularities, decreased breast size
- male pattern alopecia - Psychological
- reported feeling of well-being, invincible
- aggression, irritability, hyperactivity, change in libido, mood swings, engagement in high risk behaviors, violence, drug dependency
46
Q
Creatine
A
- increase creatine and phosphocreatine in the muscles
- creatine use is common
- improve performance of brief high-intensity exercise
- limited evidence that it can enhance performance during exercise lasting longer than about 90 sec
- creatine supplementation during resistance training may allow athletes to complete more repetitions and speed recovery
- increase muscle mass/weight
- generally considered safe
47
Q
Potential Concerns of Creatine
A
- doses and responses vary
- increase in muscle weight may reflect increase in water and there may not be proportional gains in strength
- dehydration
- GI upset
- potential renal effects with higher doses
