Regulating human performance (7.13, 7.14, 7.15, 7.16)
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Exercise is important for health and reduces the risks of many diseases.
Moderate exercise is associated with:
- Increased natural killer cells – these cells are part of the non-specific immune system and help fight viruses and cancerous cells.
- Decreased disease risk – decreased risk of diseases such as osteoporosis, CVD and type 2 diabetes.
- Maintaining overall health – increased mental wellbeing and maintenance of a healthy weight.
Both underexercising and overexercising are linked with negative health outcomes.
High levels of exercise without adequate rest and recovery can lead to overtraining.
Overexercising is associated with:
- Immune suppression. The numbers of certain immune cells decrease temporarily and can reduce the number of antibodies produced.
- Wear and tear on joints. Cartilage in the joints can start to erode, this can eventually lead to arthritis. The bursae (fluid sacs) of joints can swell and increase in size. This leads to a condition called bursitis, causing joint inflammation and pain.
Not exercising enough is associated with negative health outcomes, such as:
- Increased risk of high cholesterol.
- Increased blood pressure.
- Increased disease risk, such as type 2 diabetes, CVD and stroke.
- Increased risk of certain cancers.
- Decreased bone density.
- Increased risk of obesity.
Many of the associated risks of under- and over-exercising listed above are examples of correlation, with the direct causal link not yet discovered.
For example, the reduced number of immune cells associated with overexercising may not be caused directly by overexercising. The cause may be a related factor, such as increased psychological stress associated with overexercising.
Many athletes with sports–related injuries, such as ligament tears or arthritis, benefit from keyhole surgery.
Keyhole surgery involves using tiny cameras and surgical instruments to perform a variety of procedures. Keyhole surgeries usually have quicker recovery and are at a lower risk of bleeding and infection than typical surgery involving a large incision.
If a person’s joint becomes damaged or is affected by a health condition and other treatments are unsuccessful, they may receive a joint replacement. A joint replacement is an example of a prosthetic.
Prosthetic joint replacements usually allow a person to continue with their previous activities once they have healed. This allows people who have been injured or affected by a health condition to participate in sports.
People with disabilities or limb differences sometimes use prosthetics. Prosthetics allow people to gain some function or appearance of a limb or body part.
Athletes with disabilities or limb differences sometimes use specially developed prosthetics to participate in sports, with features such as:
- Increased friction and grip for running or climbing.
- Increased spring and recoil for running or jumping.
- An attachment for weight lifting or sports equipment (e.g., for a bike).
- Increased surface area for swimming.
Historically, drugs such as stimulants, anabolic steroids and hallucinogens have been used as performance–enhancing drugs or “doping” in sports.
Currently, athletes are banned from taking performance–enhancing drugs. If a drug is used to treat a health condition and may be associated with enhancing performance, the athlete must obtain approval to be able to use the drug.
Hormones cause changes within cells by affecting enzymes.
Hormones are either peptide hormones, such as insulin, or steroid hormones, such as oestrogen.
Some hormones act either directly or indirectly on the transcription of genes.
Peptide and steroid hormones can act in different ways on transcription factors.
Peptide hormones cannot pass through cell membranes, so they instead bind to receptors on cell membranes. This receptor causes a change within the cell by producing or converting a secondary messenger.
The secondary messenger activates transcription factors, causing a gene to be transcribed.
Steroid hormones are able to pass through cell membranes as they are lipid soluble. As steroid hormones can pass directly into the cell, no secondary messenger is required.
The steroid hormone binds to a receptor within the cell. The hormone–receptor complex can then act as a transcription factor, which can either switch transcription on or off.
