Therapeutic Exercise: Muscular Fitness Components

• Therapeutic exercise aims to assist individuals in meeting their goals through aerobic and resistance training.
• Resistance training aims to improve muscular fitness.
• Muscular fitness refers to muscle strength, hypertrophy, power, and local muscular endurance (LME).

Components of Muscular Fitness

• Strength is the maximal force generated during a specific movement pattern at a specified velocity of contraction.
• Hypertrophy is an increase in muscle size, represented by the physiological cross-sectional area.
• Power is the rate of performing work, calculated as (force x distance)/time.
• Local Muscular Endurance (LME) is the ability of muscle groups involved in a movement to sustain exercise.
• Exercise is done for appearance, improve health outcomes, work requirements, event-specific training, psychological well-being, and fun.

Systematic Approach to Exercise

• Movement/posture can cause a dynamic change in posture. This relates to the role of the muscle group which could be either a stabilizer or a dynamic/global mover. You must consider how the muscle/muscle group executes it's role, either concentrically, quasi-ometrically, or eccentrically.

• Kinematic constraints are caused by open (OKC) and closed chain (CKC) exercises, as well as sensory input. This relates to muscle architecture which could be designed for force transfer (strap muscle), or power (pennate). Alignment is a combination of posture, movement, and function continuum.

Goldilocks Effect

• Finding a balance between sufficient stimulus for muscular fitness gains to avoid decreases in muscular fitness.

General Adaptation Syndrome (GAS)

• GAS is not a syndrome but a framework describing prolonged stress effects on body
• The first reaction, alarm, is the body's initial response to a stressor described as fight or flight
• The second phase, resistance, involves adaptation and resource mobilization to meet demands.
• The final stage, exhaustion, involves depletion and leads to fatigue and decreased immune function.
• Optimal loading leads to continual improvements over time.
• Too frequent or high magnitude loading prevents adequate recovery.
• Loading that is infrequent or insufficient leads to stagnation or decline.

Estimating the 1RM Maximum Strength (ACSM Protocol)

• Use a multi-joint exercise (e.g., bench press or squat)
• Multiply the number of reps of the exercise performed to failure by 2.5.
• Subtract this product from 100 to determine % of 1RM
• Express the resulting number of reps as a ratio by dividing it by 100
• Divide the weight lifted by the outcome of the prior division to compute 1RM.
• Example: 60kg / 0.75 = 80kg
• This calculation is influenced by neural control
• The greatest measurable force exerted by a muscle or group to overcome a resistance during a single maximum effort is strength.
• Functional strength = ability of neuromuscular system to produce sufficient force to accomplish functional activities in a smooth and coordinated manner.

Determinants of Skeletal Muscle Tension

• Key factors in tension generation: muscle size, architecture, fiber-type distribution, length-tension relationship, moment arm, motor unit recruitment rates, and velocity of contraction
• A larger muscle diameter, relating to cross-section and muscle seize, results in better tension-producing capacity.
• Short fibers with pennate and multipennate designs are typical in high-force muscles.
• Type I fibers favor low force output and fatigue resistance; type IIA and IIX fibers favor rapid force production and fatigue
• Muscles near resting length produce the greatest tension.
• Longer movement arms yield greater tension.
• Greater number of motor units results in better force production.
• Higher firing frequencies increases tension.
• The highest force output occurs during eccentric contraction, followed by isometric and concentric contractions.
• Concentric contraction speed is inversely proportional to tension. Eccentric is the opposite.
• Adults must engage in resistance training exercises involving major muscle groups, minimum 1 set of 8-12 reps for at least 2 days per week.

Neural Adaptation Training (NAT) to Engage the Central Nervous System

• NAT can improve efficiency & effectiveness of nervous system in muscle contraction
• Facilitation of descending neural pathways leads to increased strength, power, and coordination
• Increases MU recruitment, improving the force production capacity
• Enhances MU synchronization, improving MU firing timing and coordination
• Improves intermuscular coordination enhancing movement effectiveness
• Increase muscle sensitivity strengthening contraction
• NAT approaches increase strength and power in training's early stages
• NAT enhances movement efficiency, lowering injury risk
• It improves muscular recovery, facilitating frequent and intense training
• NAT elevates athletic performance, especially in strength, power, and coordination

NAT Approaches

• Heavy Resistance Training involves high weights with low (1-6) reps stimulating MU recruitment.
• Plyometrics improves intermuscular coordination and responsiveness via the stretch-shortening cycle.
• Proprioceptive Exercises challenge balance and coordination improving neural efficiency.
• Electrical Muscle Stimulation (EMS) directly stimulates the nervous system, bypassing MS contraction.

Resistance Training Exercise Recommendations

• For novice trainers: target each major muscle group at least 2 days per week.
• Experienced trainers: choose frequency by personal preference.
• For novice trainers: Use 60-70% 1RM, 8-12 reps to improve muscular fitness.
• Experienced trainers: apply a wide range of intensities and reps dependent on specific goals.
• Complete Multijoint exercises for adults, which engage multiple muscle groups, targeting agonists and antagonists. Follow with single-joint/core exercises.

General Intensity Guidelines

• Load (% 1RM) that allows 8-12 reps.
• Apply the lowest resistance level to meet therapeutic goals

Prescribing Strength Training

• Untrained individuals improve at 40-85% 1RM and maximal gains occur at 60% 1RM
• Trained individuals improve at 80-100% 1RM across a wide range of loads (1-12 RM)
• Trained Strength gains occur at 80% 1RM with heavier loads (1-6 RM).
• Performance to volitional failure is the stimulus for hypertrophy.
• Apply loads ≥30% 1%M and 6-10 RM to the individual's specific needs
• Attempt to move resistance with maximal velocity for Power
• Perform 1-3 sets per exercise at a light-to-moderate load (3-6 reps per set)
• Use 30-60% 1RM for upper exercises of the body and 0-60% 1RM for the lower body.
• Increasing reps is used for Local Muscular Endurance as the demand increases.
• Light loads and high reps can impact lighter training, as well as moderate-to-heavy loads. Higher repetitions during shorter periods can provide heavy training.