Chapter 13. Nutrition and Physical Activity
Chapter Review
IMPORTANT: Key Takeaways
- Physical activity is extremely important for achieving optimal health. Some of the physical benefits of physical activity include longer life, cardiovascular disease prevention, management of chronic conditions, energy boosts, strong bones, and improved physical fitness. The mental and emotional benefits mood improvement, reduced risk/limited symptoms of depression, cognitive skills retention, and better sleep.
- The 4 elements of physical fitness are cardiorespiratory fitness, muscular fitness, flexibility, and body composition.
- Cardiorespiratory fitness is the ability of our heart, lungs, and circulation to supply oxygen and nutrients to the working muscles.
- Muscular fitness includes muscular strength and endurance, which are both developed and maintained by weight or resistance training.
- Flexibility is the range of motion available to your joints.
- Body composition refers to the proportion of fat and fat-free mass in one’s body.
- ATP supplies the energy for muscle contraction to take place.
- Once ATP stores have been depleted (~1-3 s), the creatine phosphate system helps regenerate ATP, which provides ~15 s of energy. In a resting muscle, excess ATP transfers its energy to creatine, producing ADP and creatine phosphate. When the muscle starts to contract and needs energy, creatine phosphate transfers its phosphate back to ADP to form ATP and creatine.
- Glycolysis takes place in the cytosol of the cell, in which one glucose molecule is broken down to produce 2 ATP and two molecules of pyruvic acid/pyruvate. Glycolysis cannot generate ATP as quickly as creatine phosphate.
- In the presence of oxygen, pyruvic acid/pyruvate can be as fuel for aerobic metabolism, which takes place in the mitochondria. Aerobic metabolism can use carbohydrates, fats, and proteins as a fuel source. It is much slower than anaerobic glycolysis but produces the greatest amount of ATP.
- The exercise intensity determines the type of fuel source used to produce ATP. When low-intensity activities are performed, aerobic metabolism is used to produce large amounts of ATP with fats being used as the primary fuel source. When high-intensity activities are performed, we experience a greater reliance on anaerobic metabolism with carbohydrates used as the primary fuel source to produce lower amounts of ATP but at a faster rate.
- Fat reserves are almost unlimited, so our bodies can sustain low-intensity exercises for a long period of time. However, glycogen stores are more easily depleted, which marks the onset of fatigue.
- Energy needs for athletes increase depending on their energy expenditure, which is dependent on the intensity, duration, and frequency of exercise being performed. Energy needs are also affected by an individual’s age, gender, and weight. Competitive athletes may need over 3,000-5,000 calories daily, while a typical inactive individual needs ~2,000 calories daily.
Practice Questions
- What is physical activity?
- How have the cumulative effects of colonization and modernization influenced the physical activity behaviours of Indigenous peoples today?
- What are the physical and emotional benefits of increased physical activity participation?
- Design a strength program for an individual looking to improve their muscular fitness without access to a gym membership/equipment. Include frequency, duration, and modes of exercise in your answer.
- Pretend you are a healthcare professional working with a sedentary client looking to improve their cardiorespiratory fitness level. What exercise recommendations would you make to this client? Be specific in terms of exercise intensity, frequency, type, and duration. How might you assess pre- and post-intervention changes in their cardiorespiratory fitness?
- How do exercise intensity and duration influence substrate utilization?
- How can endurance athletes avoid “hitting the wall”?
- Why is carbohydrate loading not beneficial to all athletes?
- How might societal pressures influence energy intake and disordered eating patterns?
- Say you are an endurance athlete competing in a 2-hour event. What should your carbohydrate intake look like before, during, and following the event?
- What is hyponatremia? What are some of its causes and common signs? How can hyponatremia be avoided?
