In-Depth Notes on Exercise Science and Adaptations

Graph of Adaptation

• Researcher: William Kramer
  • Known for studies related to steroids and exercise adaptation.

Key Lines in the Graph

• Overall Strength: Combination of neural adaptation and hypertrophy.
• Neural Adaptation: First response during the initial phases of training.
• Hypertrophy: Develops after a significant time; at least 6 weeks required for noticeable effects.

Time vs Strength Gains

• Y-Axis: Strength levels.
• X-Axis: Time.
• Early Training: Neural adaptations dominate strength improvement regardless of training program (e.g. 2 sets of 15 vs 4 sets of 4).
  • Faster adaptations since they don't require immediate protein synthesis.

Hypertrophy Timing

• Noticeable hypertrophic effects typically start after approximately 6 weeks of consistent training.
  • Initial strength gains from neural adaptations can feel overwhelming but will plateau over time.

Limitations of Study Data

• Kramer notes a lack of long-term studies (beyond 6-8 months) affecting understanding and predictions of adaptations after prolonged training.

General Resistance Training Adaptations

• Individuals Starting Training: Experience increases in:
  • Muscle Strength
  • Muscle Power
  • Muscle Endurance

Muscle Enzyme Concentrations

• Phosphagen Enzyme (Creatine Kinase): Important for ATP production.
• Concentration vs. Total amount:
  • Total muscle enzyme concentration increases due to overall muscle size increase; concentration may remain stable.

Lactate Dynamics

• Lactate Increase During Exercise: Generally decreases due to improved buffering systems.
  • Muscle Buffering Systems:
  • Bicarbonate: Blood buffering.
  • Carnosine: Muscle buffering, improved through training.

Muscle Fiber Adaptations

• Type 1 vs Type 2 Fiber Changes:
  • Type 2 fibers (fast-twitch) increase more than Type 1 fibers.
  • Limited research shows fiber type shifting; mainly hybrid fibers shift phenotype.
  • Aging leads to a shift from Type 2 to Type 1 fibers, reducing muscle power/size with age.

Cross-Sectional Area (CSA)

• CSA Significance:
  • Cross-sectional area of muscles increases with training.
  • Type 2 Fibers: Greater capacity for hypertrophy compared to Type 1.

Factors Influencing Muscle Strength

• Muscle Activation and Neural Function: Only factors that can be significantly altered through training include:
  • Neural Activation
  • Muscle Size
  • Other factors like muscle length and architecture remain largely unchanged.

Benefits of Resistance Training

• Fat Loss: Decreases fat percentage while increasing fat-free mass.
• Metabolic Rate Increase: Muscle mass increases metabolic rate; muscle at rest is 6 times more active than fat.
• Reduction in Injury Risk: Resistance training strengthens connective tissues, reducing the chance of injury.

Bone Density Considerations

• Increased Bone Density: Requires high intensity and volume in training; simply doing high rep doesn’t suffice.
• Necessary to load bones to stimulate osteoblast activity for safety against osteoporosis.

Neural Adaptations

1. Rate Coding: Improved action potential firing rates lead to enhanced force production and contraction speed.
2. Co-contraction: The ratio of agonist to antagonist muscle activation improves with training, leading to stronger agonist contractions.
3. Synaptic Efficiency: Increased efficiency in acetylcholine processing and release occurs across various training types.

Metabolic Goals and Hypertrophy

• Hypertrophy Pathways: Activated through mTOR and phosphatidic acid pathways.
• Acute Response: Protein synthesis increases dramatically in untrained individuals post-session compared to trained.
• Energy Availability: Protein synthesis is hindered in energy deficit situations, stunting muscle growth despite effective training protocols.