Physical Activity and Nutrition Notes

Fitness

• Fitness is the ability to perform routine physical activity without undue fatigue.

Health Benefits of Physical Activity

• Improved sleep

• Improved mood

• Exercise enhances flexibility and balance.

• Exercise increases tissue sensitivity to insulin, lowering the risk of type 2 diabetes.

• Exercise reduces cardiovascular disease risk by:

  • Strengthening the heart muscle

  • Lowering blood pressure

  • Increasing HDL (good) cholesterol levels

• Regular exercise reduces the risk of colon and breast cancer.

• Exercise increases muscle mass, strength, and endurance.

• Weight-bearing exercise stimulates bone density, reducing the risk of osteoporosis.

• Improved joint function due to strength and flexibility.

Physical Activity Guidelines for Americans

• Daily: Integrate activity into daily life, including flexibility exercises.

  • Choose an active lifestyle.

  • Incorporate activities like walking the dog, taking stairs, and standing up often.

  • Stretching exercises improve flexibility but don't count toward aerobic or strength activity recommendations.

• 5+ days/week: Engage in moderate or vigorous aerobic activities.

  • Minimum of 150 minutes of moderate-intensity aerobic activity per week (e.g., brisk walking, ballroom dancing).

  • Or 75 minutes per week of vigorous aerobic activity (e.g., bicycling >10 mph, jumping rope).

  • A mix of moderate and vigorous activity (1 minute vigorous = 2 minutes moderate).

• 2+ days/week: Engage in strength activities.

  • Moderate to high intensity muscle-strengthening exercises involving all major muscle groups.

• Seldom: Limit sedentary activities.

  • Reduce TV/movie watching and leisure computer time.

Intensity of Physical Activity (Table 10-1)

• Light: Little to no increase in breathing/heart rate.

  • Perceived exertion: <5 (on a scale of 0-10)

  • Talk test: Able to sing

  • Energy expenditure: <3.5 cal/min

  • Walking pace: <3 mph

• Moderate: Some increase in breathing/heart rate.

  • Perceived exertion: 5 or 6

  • Talk test: Able to have a conversation

  • Energy expenditure: 3.5 to 7 cal/min

  • Walking pace: 3 to 4.5 mph (100 steps per minute or 15-20 minutes to walk 1 mile)

• Vigorous: Large increase in breathing/heart rate.

  • Perceived exertion: 7 or 8

  • Talk test: Conversation is difficult or "broken"

  • Energy expenditure: >7 cal/min

  • Walking pace: >4.5 mph

Muscle Adaptation to Exercise

• Overload principle: The body adapts to the stresses placed on it.

• Stress/overload during exercise causes muscles to adapt by increasing in size and strength (hypertrophy).

• When muscles are not used, they atrophy (become smaller and weaker).

• Exercise builds and maintains muscles, resulting in a greater proportion of lean body tissue.

Aerobic Exercise and Heart Health

• Cardiorespiratory Endurance: Characteristics include:

  • Increased heart strength and stroke volume

  • Slowed resting pulse

  • Increased breathing efficiency

  • Improved circulation and oxygen delivery

  • Reduced blood pressure

  • Increased blood HDL cholesterol

Diet for Athletes

• Key components:

  • Carbohydrates (sugar)

  • Protein

  • Healthy fats

  • Water/electrolytes

Importance of Hydration

• During exercise, water is needed to:

  • Eliminate heat

  • Transport oxygen and nutrients to muscles

  • Remove waste products (e.g., lactic acid)

• Hydration levels affect the body's ability to perform these functions.

• If heat cannot be lost, body temperature rises, impairing exercise performance and health.

Suggested Hydration Schedule for Physical Activity (Table 10-8)

• Fluid needs vary based on weight, genetics, hydration level, training, environment, and other factors.

• 24 hours before activity: 5 to 7 ml/kg body weight (e.g., 70-kg athlete: 1\frac{1}{2} to 2 cups; 55-kg athlete: ≈1 to 1\frac{1}{2} cups).

• 2 hours before activity: If heavy sweating is expected, additional 3 to 5 ml/kg (e.g., 70-kg athlete: ≈1 cup (9 ounces); 55-kg athlete: ≈1 cup (7 ounces)).

• During activity: Limit dehydration to <2% body weight. A personal hydration plan is recommended.

• After activity: Drink ≥2 cups for each pound of body weight lost. Hydrate rapidly with divided doses (2 cups every 20-30 minutes).

Monitoring Water Loss

• Weigh before and after exercise. For every pound lost, drink 2 x 8 fl. oz. of water.

Sports Drinks

• Both individuals need to replace fluids.

• Key components:

  • Fluid

  • Glucose

  • Percentage glucose

  • Sodium and other electrolytes

  • Psychological edge

Other Beverages

• Carbonated beverages

• Caffeine:

  • Moderate doses are acceptable.

  • Excess sugar can be detrimental.

• 100% fruit juice:

  • Potential for excess sugar.

• Alcoholic beverages:

  • Diuretic; avoid >400 ml before working out.

Macronutrient Considerations for Athletes

• Carbohydrates, protein, and fat.

Carbohydrates

• Glucose: A major fuel for physical activity.

  • Liver glycogen is for the brain/nerves & RBC.

  • Muscle glycogen is retained for muscle use.

  • Glycogen stores are limited.

  • Brain is #1 priority, Muscles-last priority.

Glycogen Before and After Physical Activity

• Glycogen stores are full before activity and depleted after exercise.

Effect of Exercise Intensity on Fuel Use

• Rest

  • Fatty acids are the primary fuel source.

• Moderate-intensity activity

  • A mix of fatty acids and glucose is used.

• High-intensity activity

  • Glucose is the primary fuel source.

  • Amino acids contribution is minimal across all intensities.

Carbo-Loading

• Technique to maximize glycogen stores.

• Diets:
  *High-fat diet: 57 min
  *Normal mixed diet: 114 min
  High-carbohydrate diet: 167 min Maximum endurance time: These are example numbers

Carbohydrate Recommendations for Athletes

• Postpone fatigue and maximize performance.

• Need for abundant carbohydrate.

• Consume glucose:

  • Before activity

  • During activity

  • After activity (1-2 hours)

Examples of High-Carbohydrate Pregame Meals:

• Vary based on timing before exercise (1, 1-2, or 2-3 hours).

• Examples provided for different caloric and carbohydrate levels.

Nutritious High-Carbohydrate Meals for Athletes

• Examples provided for 2,600 and 3,300 calorie diets, with macronutrient breakdowns.

Protein

• Protein's role in building muscle.

• Requires high-quality protein in the diet.

• Repeated muscle contractions (Animal protein) ->digestable :Absorbable

Recommended Protein Intakes for Athletes (Table 10-6)

• Depends on the sport.
  *Daily protein intakes are based on a 70-kilogram (154-pound) reference man and a 55-kilogram (121-pound) reference woman. To convert pounds to kilograms divide lb by 2.2. (\frac{lb}{2.2})

• Recommended intake for power (strength or speed) athletes: 1.2-1.7 g/kg/day.

• Recommended intake for endurance athletes: 1.2-1.4 g/kg/day.

Timing of Protein Intake

• Muscle building is highest in the 2 hours after exercise.

• Continues for 24-48 hours post-activity.

• Example: 20 grams ( small ahy breast 1202 yogurt)

Iron – A Mineral of Concern

• Iron deficiency impairs performance.

• Sports anemia can occur.

• Groups at risk for deficiency.

• Vitamin C Important-Most↓

Sports Anemia

• Comparison of normal vs. sports anemia.

Foodborne Illness

• Symptoms:

  • Nausea

  • Vomiting

  • Diarrhea

  • Fever

  • Others

• Statistics:

  • CDC estimates:

  • 76 million people get sick each year

  • 300,000 are hospitalized

  • 5,000 Americans die

• Most susceptible:

  • Infants/children

  • Elderly

  • Immuno-compromised

What is Foodborne Illness?

• An infection or illness often caused by bacteria or a virus transmitted by food.

• Cause:

  • Microbes

  • Toxins

Bacterial Growth

• Bacterial growth over time (hours) 105cells, 106, 107, 108 is shown in a graph.

Essentials for Microbial Growth

• Nutrients

• Water

• Temperature

• Time

Prevention

• Fight BAC! Principles: *CLEAN: Wash hands and surfaces often.

  • SEPARATE: Don't cross-contaminate.

  • COOK: Cook to proper temperatures.

  • CHILL: Refrigerate promptly.