Therapeutic Interventions Week 3 - Resistance Training

Resistance Training Foundations

• Resistance training utilizes various energy systems, influenced by duration and intensity.
• Phosphagen system dominates extremely high-intensity, short-duration (<6 seconds) activities like maximal box jumps.
• Phosphagen and fast glycolysis are the crucial energy systems for very high-intensity activities (6-30 seconds), such as repeated sprinting.
• Fast glycolysis is the predominant system for activities lasting 30 seconds to 2 minutes.
• Fast glycolysis and oxidative systems are engaged for moderate-intensity, 2-3-minute activities.
• The oxidative system is prioritized for prolonged, low-intensity endurance efforts (>3 minutes).

Mechanics of Resistance Training

• External torque describes the resistance encountered by a muscle during an exercise, like gravity pulling on a weight in a bicep curl.
• External torque is influenced by gravity, mass of body segments, added weights, and the distance or lever arm from the joint.
• Internal torque arises from muscle force influenced by the muscle's lever arm, point of insertion, angle of insertion, and force production. Factors like muscle cross-sectional area, pennation angle, contraction velocity, and joint angular velocity further influence internal torque.
• Concentric contractions involve muscle shortening during movement.
• Isometric contractions occur when muscle tension is maintained but there's no change in muscle length, or joint angle.
• Multi-angle isometrics target a wider range or joint angles.
• Eccentric contractions involve muscle lengthening during movement. These actions are associated with greater muscle damage while enhancing tendon strength—useful in rehabilitation for tendinopathies.

Resistance Exercise Dosing

• Exercise prescriptions require consideration of the individual's goals (strength, power, hypertrophy, endurance) and their existing fitness levels.
• Key variables in exercise prescription include:
  • Repetitions: Range tailored to the goal (2-6 reps for strength, 7-12 for hypertrophy, 12+ for muscular endurance).
  • Sets: Number of repetition series, ranging from 2-6 for strength, 3-6 for hypertrophy, and 2-3 for endurance.
  • Load: Percentage of one-rep max (1RM) related to goal (Strength >85% of 1RM, Hypertrophy 67-85% of 1RM, Endurance <67% of 1RM).
  • Rest intervals: 2-5 minutes for strength and power; 30-90 seconds for hypertrophy, and less for endurance.
• Proper estimation of resistance is critical, adjusting load as needed based on the number of repetitions completed.
• Rating of Perceived Exertion (RPE) can also be used to gauge intensity (1-2 = easy, 3-4 = moderate, 5-6 = hard, 7-8 = very hard).

Exercise Modifications and Progression

• Progressive overload is crucial for adaptation and improvement, involving adjusting load, variations in exercise type, or changing the movement form/speed.
• The SAID principle (Specific Adaptation to Imposed Demands) suggests exercises should match the activities, movements, speed, and range of motion needed for desired functional outcomes. Exercise modifications, such as changing load, movement speed, support, or complexity, are integral to progression.

Adaptations to Training

• Neural adaptations: Early gains in strength are often due to neural adaptations, like better motor unit recruitment, crucial especially after injuries where neural inhibition may hinder strength.
• Muscular adaptations: Hypertrophy involves increased myofibril number and size, and enhanced insulin sensitivity, essential for individuals with Type II diabetes. Glycogen storage also benefits athletes, supporting endurance capacity.
• Connective tissue adaptations: Bone density improves with higher strain rates and magnitude loading (power training), important for preventing osteoporosis and osteopenia. Tendons and ligaments strengthen with increased collagen fibrils and cross-linking, useful in recovery or prevention of injuries. Cartilage health depends on loading and unloading for nutrient diffusion and enhanced thickness, preventing osteoarthritis.
• Cardiovascular adaptations: Cardio-respiratory adaptations from strength training don't impair endurance performance.

Clinical Application and CPT Codes

• Various CPT codes are assigned to specify therapeutic exercise types (97110 for therapeutic exercise, 97112 for neuromuscular re-education, 97116 for gait training, 97530 for therapeutic activities).
• Specific therapeutic exercise programs consider the underlying issues, like pain, impaired activity, motor control, or mobility issues.
• Treatment approaches vary depending on the nature of the problem and the specific tissue or system affected.