The Physiology of Resistance/Strength Training Flashcards
Define Muscular strength
Maximal force that a muscle group can generate (1-RM)
Define Muscular endurance
Ability to make repeated contractions against a submaximal load
Strength training - how many reps till fatigue in high-resistance and low-resistance training?
*High-resistance training (that is 6 to 10 reps till fatigue).
- Results in strength increases.
* Low-resistance training (that is 35 to 40 reps till fatigue).
- Results in increases in endurance
What does ageing result in?
A loss of muscle mass and strength
- loss of muscle mass (sarcopenia)
- atrophy type 2 fibres
- reduced number of both type 1 and 2 muscle fibres
- Resistance training promotes hypertrophy/strength gains in older individuals but lower than young individuals.
What is responsible for early gains in strength, and what is this evidenced by?
Neural adaptations - as evidenced by:
- muscular strength increases in first 2 weeks of training without increase in muscle fibre size
- phenomenon of “cross-education” - training of one limb results in increases of strength in UT limb
What adaptations within the muscle fibre occur later on…?
- increased muscle fibre specific tension
- increased muscle mass
What adaptations are included in the early gains related to changes in nervous system?
- Increased Neural Drive (measured via EMG).
- Increased number motor units recruited.
- Increased firing rate of motor units.
- Increased motor unit synchronization.
- Improved neural transmission across neuromuscular junction.
What is the mechanism responsible for training-induced increase in specific tension in type 1 fibres?
Appears to be linked to increased calcium sensitivity - results in greater number of cross-bridges bound to actin
Define hyperplasia
Increased number of fibres
Define Hypertrophy
Increased CSA of muscle fibres
- likely dominant factor in resistance training-induced increases in muscle mass.
- due to actin and myosin
- evidence of resistance training-induced transition from type IIx to IIa (but not type II to type I)
Protein synthesis must exceed breakdown for ? weeks or more to achieve significant fibre growth
3 weeks or more
What are the key factors which contribute to resistance training-induced increases in MPS (signalling events)?
- mRNA increases resulting in PS at ribosome
- Ribosomes increase in number and elevate muscle’s PS capacity
- Activation of the protein kinase mTOR is the KEY FACTOR ACCELERATING PROTEIN PS following bout of resistance training
What 2 signalling molecules stimulate mTOR activation?
Phosphatidic acid (PA) & Ras homolog enriched in brain (Rheb)
Time course of molecular responses to resistance training - What are the post-exercise molecular responses ?
Secs - increased Rheb and PA
Mins - increased mTOR activation
Hours - increased PS
What other hormones are linked to mTOR activation
IGF-1 and GH