Lecture 37 Flashcards
What is the difference between aerobic and anaerobic exercise in terms of energy?
Anaerobic exercise is high intensity, involves rapid generation of energy over short periods (using phosphocreatine or glycogen (no oxygen). Aerobic exercise is low intensity, prolonged and sustained exercise (using oxidation of glucose and fatty acids). These are not independent and as such exercises will have different relative components.
What is myosin ATPase and how long can it be powered without replacement of ATP?
Myosin ATPase is the protein which is involved in contraction via the formation of the myosin and actin cross bridges, usage converts ATP to ADP + inorganic phosphate. This must be resynthesised constantly as our stores in the muscle are normally only enough to last one second.
How is phosphocreatine used by muscles as fuel? What happens if creatine supplements are taken?
Phosphocreatine is an “on site “,”fast fuel”, theres roughly 20 umol per g of muscle (lasting about 9-10 seconds) and involves hydrolysis of high energy phosphate bonds to make ATP and creatine via the creatine kinase enzyme (no oxygen needed). It is made from arginine and glycine. Taking creatine supplements have been shown to help increase work output in individuals, more in some people than others (only due to ingestion amount varying between people).
How is glycogen used as fuel in the muscles? What is the problem?
Glycogen is an ‘on-site’ store of glucose in muscle, it is mobilised to glucose 1-phosphate by glycogen phosphorylase, this is then converted to glucose 6-phosphate (mutase) and this is the fuel for anaerobic glycolysis (producing pyruvate and then to lactate which oxidises the NADH back to NAD+ for more pyruvate production). This can last about 20 seconds before lactate levels become to high and pH drops to low (leading to fatigue). It is stimulated by Ca++ and adrenaline, phosphofructokinase activity will b increased by allosteric regulators (AMP and inorganic phosphate), adenylate kinase (myokinase, will combine two ADP to make one ATP and one AMP).
Where do the supplies for aerobic generation of ATP come from? How can creatine help?
Blood supplies the fuels and oxygen for aerobic generation of ATP, it involves the active citric acid cycle, and electron transport chain/oxidative phosphorylation. Carnitine is involved in transporting acyl-CoA across the mitochondrial membranes, there is no evidence that supplements of it help. High carbohydrate diets can help though.
What are the two main muscle fiber types?
The two main fiber types are type I (red, slow-twitch, oxidative) (mainly in low intensity) and type II (white, fast-twitch, glycolytic) (mainly in high intensity).
What are the muscle adaptations to endurance training?
Muscle adaptations to endurance training includes: more type I fibred, more blood capillaries per muscle fibre, increased myoglobin content, increased size and number of mitochondria (SEE SLIDE).
What are some examples of performance enhancing drugs?
Performance enhancing drugs include: EPO doping (increases red blood cell count), anabolic steroids (muscle size), growth factors (recombinant IGF-1 and GH). Gene therapy is a future possibility e.g myostatin (turning it off to stop inhibition of muscle growth).
