Module 4 Flashcards
Which broad factors contribute to exercise non response?
- training parameters
- measurement methods
- genetics
- epigenetics
What factors contribute to Measurement Error?
- Technical error of the measurement
- Test-retest reliability
Technical error refers to the inherent variability of the testing method, while test-retest reliability indicates the consistency of results when a test is repeated.
How does Measurement Error impact the assessment of training effects?
If observed changes fall within the measurement error, it’s difficult to conclude if a true physiological change has occurred.
This can lead to misclassification of individuals as non-responders.
What happens if the change in measured value is smaller than the error associated with the measurement?
Individuals might be labeled as non-responders.
This mislabeling can occur despite potential physiological changes that are not detected due to measurement error.
What is heritability (H²)?
The amount of variance in a population accounted for by inherited genetic information
Heritability can vary with environmental factors.
How is heritability estimated?
Based on relatedness of individuals and trait similarity
For instance, siblings share about 50% of their genes.
What was the heritability estimate for aerobic trainability found in studies?
Around 50%
The HERITAGE family study supported this estimate.
What do genome-wide association studies (GWAS) aim to identify?
Specific genes important for trainability
GWAS look for single nucleotide polymorphisms (SNPs) associated with training responses.
What is a polygenic score?
A score that combines effects of multiple SNPs to estimate variance explained by DNA
These scores often do not align with heritability estimates and can overfit to specific populations.
Which candidate genes have been associated with performance phenotypes?
ACE and ACTN3
These genes suggest a slight increased or decreased propensity for certain activities, but are not deterministic.
What role does the environment play in exercise adaptation?
A significant role, often overestimated compared to genetics
Factors include diet, lifestyle, sleep, and epigenetics.
What do twin studies suggest about exercise adaptation?
Most differences in adaptation may be due to environmental factors rather than genetic differences
This is indicated by comparing identical and fraternal twins raised in similar environments.
What is the estimated heritability of aerobic trainability?
Around 50%
This indicates that approximately half of the variability in aerobic trainability can be attributed to genetic factors.
What are the cons of using GWAS?
- need big samples to find rare variants
- only correlational
- polygenetic scores don’t reach H2
- there is little consensus
- risk of model overfit
What does epigenetics refer to?
Changes to our genome that do not involve alterations to the underlying DNA sequence.
List the epigenetic changes we discussed in class
- histones
- methylation
- micro RNA
- acetylation
What is DNA methylation?
The addition of a methyl group to specific parts of our DNA, making it harder for those genes to be expressed.
How does exercise affect DNA methylation?
Exercise can lead to hypomethylation, a reduction in methylation, allowing for increased gene transcription.
What are histones?
Proteins that DNA wraps around, affecting how tightly the DNA is packaged.
What is the effect of histone modifications?
They can affect gene transcription by altering the accessibility of DNA.
What are microRNAs (miRNA)?
Small, non-coding RNA molecules that bind to mRNA and can inhibit protein production.
How does exercise influence microRNA levels?
Exercise can affect the transcription of microRNAs.
What role does the environment play in epigenetics?
Factors like exercise, diet, and lifestyle can lead to changes in DNA methylation, histone modifications, and microRNA levels.
What is the concept of Developmental Origins of Health and Disease (DoHaD)?
The idea that the environment a developing fetus or baby is exposed to can have long-term health consequences.
What did the Dutch Hunger Winter study demonstrate?
Individuals born during severe food scarcity had a higher likelihood of obesity and metabolic issues later in life, potentially due to epigenetic changes.
What role do epigenetic modifications play in exercise adaptation?
They can lead to fluctuations in the epigenetic state, affecting gene transcription and resulting in training adaptations.
How can exercise affect gene transcription for muscle growth?
Exercise can decrease methylation on certain genes, allowing for increased transcription necessary for muscle growth.
Fill in the blank: Epigenetics provides a layer of regulation above and beyond our _______.
DNA sequence.
True or False: Epigenetic modifications can influence our ability to adapt to training.
True.
What is prediction in exercise science?
Forecasting how an individual will respond to a specific training program before starting
Involves identifying pre-training characteristics that could indicate response levels.
What is the current ability to predict individual responses to exercise?
Limited, especially for resistance training-induced hypertrophy
Many factors remain uncertain, indicated by the phrase ‘a lot of things with three question marks.’
What are potential predictors for exercise response according to current evidence?
Limited evidence for pre-training markers, including:
* Fibrotic muscle
* Satellite cell population and capillarization
* Fiber type
* Genetic markers
How does fibrotic muscle affect exercise response?
Individuals with very fibrotic muscle might be lower responders
Fibrotic muscle has more collagen and extracellular matrix.
What impact do satellite cell populations have on muscle gain?
Depleted satellite cell populations might not gain as much muscle
Evidence primarily comes from older, potentially impaired populations.
Does pre-training fiber type composition predict hypertrophy?
No, it does not consistently predict hypertrophy in studies
More type II fibers do not guarantee greater muscle growth.
What is the status of genetic markers in predicting exercise response?
GWAS have not reliably identified specific genes or polygenic scores with strong predictive value
Many identified genes lack consistent replication across studies.
What does postdiction of exercise response involve?
Looking back after a training intervention to explain differences in individual responses
Provides insights into why some individuals respond differently than others.
List all the potential postdictions for exercise response
- Muscle Protein Synthesis (MPS)
- RNA Concentration
- Androgen Receptors (AR)
- Satellite Cells and Myonuclei
- MicroRNA (miRNA) Response
- Collagen and Extracellular Matrix (ECM)
- Inflammation
- Angiogenesis and Mitochondria
What is a key factor that differentiates high responders in muscle gain?
Superior increases in both basal and post-exercise muscle protein synthesis
Particularly evident after the initial adaptation phase.
What role does RNA concentration play in muscle gain?
Gainers often show a greater ability to increase their RNA concentration
Reflects an expansion of the ribosome pool and translational capacity.
What is suggested about androgen receptors in high responders?
They may have higher pre-training androgen receptor content
This group experiences greater training-induced increases in AR protein.
How do satellite cells and myonuclei relate to muscle gain?
High responders might experience superior training-induced increases in satellite cell number and myonuclear addition
This is particularly relevant for extreme hypertrophy.
What is the ‘bag full hypothesis’ regarding ECM?
A poorly organized extracellular matrix might constrain muscle fiber expansion
Non-responders may have ECM characteristics that limit remodeling.
How does inflammation affect hypertrophy?
Chronically high baseline inflammation might hinder hypertrophy
This is especially relevant for older adults or those with certain conditions.
What is the relationship between angiogenesis and hypertrophic response?
Differences in capillarization and mitochondrial content/function are less clearly linked to hypertrophic response
Very low levels might be limiting but are not consistently predictive.
What challenges exist in accurately predicting exercise response?
Complexity and interplay of factors, along with individual variability in genetics, epigenetics, and environment
Makes it difficult to predict who will be high or low responders.
What might the concept of ‘non-responders’ indicate?
An insufficient training stimulus or focusing on a single outcome measure
Individuals may still experience other beneficial adaptations to exercise.
What strategies can elicit a response in initially perceived non-responders?
Increasing training volume and adjusting other training variables
Often effective in eliciting a response.
