WK10 ( CH 13 ) - The Physiology of Training: Effects of Aerobic and Anaerobic Training Flashcards
Describe the principles of AEROBIC training; overload, reversibility, specificity
overload: the principle that a tissue must be exercised to a level beyond which it is accustomed to receive training adaptations.
reversibility: refers to the fact that the fitness gains achieved by exercising at an overload are quickly lost if training is stopped and overload is removed
specificity: exercise training is specific to the muscles involved in that activity. This correlates to fiber type used and adapted. specificity can also refer to the types of adaptations occurring in muscle as a result of training.
What are the factors that determine VO2max and what kind of exercise program would you prescribe to someone looking to increase their VO2max ?
Some factors that determine VO2max are prior level of VO2max, those with lower starting VO2max values have greater potential for improvement compared to those starting with a high VO2max value. VO2 is dependent on their age, health, and training status. Genetics also play a significant role in VO2 capacity, for example having high percentage of slow twitch fibers with a large cardiovascular capacity, as well as differences in mitochondrial DNA.
Generally programs that prescribe dynamic exercise using a large muscle mass for greater than 20 minutes a day, three or more times a week, at 50% VO2max is enough to improve VO2max.
Describe improvements in muscle antioxidant capacity as a result of endurance training.
Endurance exercise produces free radicals that may cause damage to muscular tissues during exercise therefore as an adaptation to muscular stress, the muscle produces more endogenous antioxidants to neutralize free radicals.
Describe changes in muscle fiber type and capillary supply with endurance training.
Muscle fibers during endurance training shift from fast to slow, using less ATP for more work ( more efficient ), this due to a reduction of fast myosin in the muscle and an increase in slow myosin isoform. slow myosin has less ATPase.
Endurance training increases the capillary supply to skeletal muscle fibers of trained individuals, this reduces diffusion distance of oxygen and substrate delivery which is favorable.
Describe the changes in mitochondrial content with endurance exercise.
endurance training can improve volume(size) of subsarcolemmal mitochondria and intermyofibrillar mitochondria within the first five days of training, prolonged training can increase mitochondrial content by 50-100% within the first six weeks of training.
What are the effects of endurance training on muscle fuel utilization ?
Endurance training promotes biochemical changes that assist in maintaining a constant blood glucose concentration during prolonged submax exercise. There is a shift from glucose to fat metabolism.
Describe the adaptations which make fat metabolism more feasible during prolonged submax exercise.
Endurance training increases fat metabolism during submax exercise by boosting the delivery of fat to the muscle and expanding the muscle’s ability to metabolize fat. fat delivery is accomplished by three adaptations (1) increased capillary density (2) expanded ability to transport FFA across the sarcolemma (3) improved capacity to move FFA from the cytoplasm into the enlarged mitochondrion
Fat metabolism occurs in the mitochondria through the beta oxidation cycle to produce Acetyl-CoA which can enter the Krebs cycle to produce ATP.
Discuss and describe the primary signal transduction pathways in skeletal muscle for adaptation.
mechanical stimuli: mechanical force placed on muscles triggers signaling processes to promote adaptations such as increased protein synthesis
calcium: free calcium in the cytosol can activate numerous enzymes and other signaling molecules that can promote protein synthesis. For example, calcium dependent kinase which phosphorylates proteins which leads to a cascade in muscle fibers that contributes to adaptations during exercise. Depending on the mode, intensity, and duration of exercise calcium is released from the SR and thus allowed to carry out different interactions that may be responsible for the adaptations seen in different methods of exercise.
free radicals: free radicals as a result of exercise trigger NFkappaB and p38 which act as second messengers to alter the gene expression of certain proteins, including antioxidant enzymes that neutralize free radicals.
phosphate/muscle energy levels: high levels of ATP consumption leads to a higher AMP/ATP ratio in muscle fibers which activates AMPK which leads to muscular adaptations.
How is the following second messenger activated and what is their general purpose:AMPK
AMPK is activated by changes in muscle fiber phosphate/energy levels. AMPK stimulates uptake of glucose and metabolism of fatty acids. AMPK is also linked to the control of muscle gene expression by activating transcription factors associated with fatty acid oxidation and mitochondrial biogenesis. AMPK can also inhibit components of the mTOR signaling pathway.
How is the following second messenger activated and what is their general purpose: p38
mitogen activated kinase (p38)
- endurance induced production of free radicals is a major signal to activate p38 in muscle fibers. once activated p38 can contribute to mitochondrial biogenesis by activating PGC-1alpha.
How is the following second messenger activated and what is their general purpose: PGC-1alpha
this molecule is activated by high intensity interval training and submax endurance exercise and is considered the main regulator of mitochondrial biogenesis in cells. Furthemore, it can assist in the formation of new capillaries, the transition of fast to slow fibers, and synthesis of antioxidant enzymes.
How is the following second messenger activated and what is their general purpose: CaMK
contributes to the activation of PGC-1alpha. It’s activation is dependent on increased cytosolic calcium.
lHow is the following second messenger activated and what is their general purpose: calcineurin
- phosphotase ( enzyne that removes a phosphate group from molecules)
- activated by elevated cytosol calcium levels and participates in adaptive responses such as fiber growth and regeneration and the fast to slow transition.
How is the following second messenger activated and what is their general purpose: NFkappaB
- a transcriptional activator that can be activated by free radicals that are produced in contracting muscles. Promotes the expression of antioxidant enzymes.
How is the following second messenger activated and what is their general purpose: mTOR
a protein kinase that is the major regulator of protein synthesis and muscle size.
Stimulated by action of mechanoreceptors on the sarcolemma of the muscle.
