Physical activity Flashcards
What are the 3 different types of muscle cells?
TypeIIB GF
- Low number of mitochondria
- Low resistance to fatigue
- High ATPase activity
- High contraction speed
- Anaerobic –> predominant energy system
- Low myoglobin content
- Glucose main fuel –> quick production of energy through the anaerobic pathway
Type IIA FOG
- Moderate number of mitochondria
- Moderate/ high resistance to fatigue
- High ATPase activity
- High contraction speed
- Anaerobic/ aerobic
- Low myoglobin content
TYPE I SO
- High number of mitochondria
- High resistance to fatigue
- Low ATPase activity
- Low contraction speed
- Aerobic
- High myoglobin content
How can exercise affect appetite?
Exercise can be useful to control the release of ghrelin in the stomach (appetite hormone)
How can exercise affect leptin sensitivity?
Exercise can reduce the release of leptin due to a reduction in adipose mass. The leptin produced is more sensitive and can be linked to improved insulin sensitivity.
The reduction of leptin productions
How can exercise affect vascular function?
Not a lot of exercise is required to create a difference in blood pressure.
After exercise, there is a period of time when blood pressure drops below baseline levels.
Exercise causes an increase in cardiac output, due to increase blood flow, which delivers oxygen and nutrients to active tissues. Stroke volume will also increase. Peripheral resistance reduces. CO increases more than PR reduces causing blood pressure to increase.
After this, in the recovery period, there is an increase there is a drop in blood pressure for a few hours. There is a rapid drop in heart rate in recovery causing a decrease in stroke volume and cardiac output –> decreasing bp.
Increasing blood flow –> increase mechanical stimuli –> more eNOS –> more NO –> vasodilation
Overall increased vascular response
NO has a very short life so nitrates are often formed, nitrate can be absorbed in the mouth (salivary glands) –> excreted in the oral cavity –> nitrite produced –> recycled into nitric oxide
What advice is given to those with high CV risk and obesity when starting exercise?
Why?
Start with lower intensity and slowly build up.
The increase in blood pressure during exercise could be more harmful to the individual, especially if they suffer from atherosclerosis, the increased cardiac output could cause displacement of an atherosclerotic plaque or other cardiovascular events.
Also will take longer to recover afterward.
After moderate training and adaptation, higher-intensity exercise might be okay.
How does exercise have an effect on NO?
Increasing blood flow –> increase mechanical stimuli –> more eNOS –> more NO –> vasodilation
Overall increased vascular response
NO has a very short life so nitrates are often formed, nitrate can be absorbed in the mouth (salivary glands) -> excreted in the oral cavity –> nitrite produced –> recycled into nitric oxide
What is VO2 max?
The maximum amount of oxygen that an individual can utilize during intense or maximal exercise.
The best indicator of CV fitness and aerobic endurance
VO2 max takes into account pulmonary diffusing capacity, cardiac output, oxygen-carrying capacity, and ability to use oxygen in skeletal muscles.
Higher value = higher ability to use fatty acids
Higher value = lower risk of cardiovascular diseases
Measured in a lab
What factors does VO2 max depend on?
Gender
Age
Genetics/ Physiology
Body type/ composition
Training status
Exercise type
Body mass –> requires more oxygen to go to the tissues
What happens to glucose homeostasis during exercise?
Insulin requirements do not change during exercise, and remain constant.
The ability to absorb glucose is higher.
Happens to everyone, including diabetics and non-diabetics.
How do muscle contractions affect glucose uptake?
Phosphorylate and activate AMPK, reduce ATP: ADP-AMP ratio
Contraction –> calcium into cell –> upregulate CaMKII –> help translocate glucose transported to the cell membranes for glucose uptake.
More nitric oxide produced –> signaling molecules –> translocation of glucose transporter to cell membrane
The ability to absorb glucose during exercise is much higher, without the need for insulin. Remains this way for a few hours, and can even extend to 48-72 hours depending on the stimulus.
More glucose sensitive, technically less glucose needed.
Diabetics who are active will require lower doses of insulin.
What are some key points to know about physical activity?
- Exercise training can shift muscle fibre phenotype according to the stimulus (intensity, duration, frequency of exercise, consistency and increasing of stimulus)
- VO2max is an important physiological parameter related to exercise capacity and risk of cardiovascular disease
- Some evidence suggests that exercise may regulate appetite by controlling ghrelin levels
- Acute exercise enhances leptin and insulin sensitivity and skeletal muscle glucose uptake through a non-insulin stimulated pathway
- Acute exercise also reduces blood pressure. Oral bacteria may be involved in these physiological responses
- 150min/ week is the amount of exercise recommended by to optimise the benefits of exercise and lower cardiovascular risk, this should be increased up to 7-10hours/ week.
