REVIEW: Power and Force

Chikara to chikara [力と力]

by CEJames & Akira Ichinose

Generating physical force and power efficiently relies on optimizing biomechanics, neuromuscular recruitment, and energy transfer while minimizing wasted effort. This applies across martial arts, athletics, and strength training. Here’s a structured explanation:

1. Biomechanical Principles of Efficient Force Generation

a. Ground Reaction Force (GRF)

• Force originates from the interaction with the ground; pushing into the ground creates an equal and opposite reaction (Newton’s 3rd law).

• Efficient movement channels GRF through aligned joints into the target.

• Reference: McGinnis, P. M. (2020). Biomechanics of Sport and Exercise. Human Kinetics.

b. Sequential Summation of Movement (Kinetic Chain)

• Power increases when body segments fire in sequence: large proximal muscles (hips, core) initiate motion, followed by smaller distal segments (arms, hands).

• Prevents “energy leaks” and maximizes angular velocity at the point of contact.

• Reference: Bartlett, R. (2007). Introduction to Sports Biomechanics. Routledge.

c. Structural Alignment and Leverage

• Stacking joints along force vectors reduces muscular strain and improves energy transfer.

• Misalignment dissipates power as shear forces.

• Reference: Enoka, R. M. (2015). Neuromechanics of Human Movement. Human Kinetics.

2. Neuromuscular Efficiency

a. Rate of Force Development (RFD)

• Training the nervous system to recruit motor units quickly increases explosive power.

• Techniques: plyometrics, Olympic lifts, ballistic throws.

• Reference: Aagaard, P., & Andersen, J. L. (2010). Effects of strength training on endurance capacity in top-level endurance athletes. Scandinavian Journal of Medicine & Science in Sports.

b. Intermuscular Coordination

• Agonist, antagonist, and stabilizer muscles must work synergistically.

• Relaxation of non-essential muscles conserves energy and prevents “braking.”

• Reference: Komi, P. V. (2003). Strength and Power in Sport. Blackwell Science.

3. Elastic and Rotational Mechanics

a. Stretch-Shortening Cycle (SSC)

• Pre-stretching muscles/tendons stores elastic energy, released during contraction (e.g., jump, punch, throw).

• Enhances efficiency by using passive tissue properties.

• Reference: Wilson, J. M., et al. (2012). Stretch-shortening cycle performance enhancement. Journal of Strength and Conditioning Research.

b. Torque and Rotational Power

• Rotational movements (hip/torso twist) increase angular momentum, critical for strikes, throws, and lifts.

• Reference: Zatsiorsky, V. M., & Kraemer, W. J. (2006). Science and Practice of Strength Training. Human Kinetics.

4. Core and Breathing Integration

a. Intra-Abdominal Pressure (IAP)

• Coordinated breathing and core bracing stabilize the spine, enabling stronger force transfer.

• Reference: Hodges, P. W., & Richardson, C. A. (1996). Inefficient muscular stabilization of the lumbar spine associated with low back pain. Spine Journal.

b. Breath-Power Coupling

• Forceful exhalation during exertion synchronizes muscular activation and reflexively enhances core stiffness.

• Applied in martial arts (kiai), powerlifting (Valsalva), and sprinting.

• Reference: McGill, S. (2010). Ultimate Back Fitness and Performance. Backfitpro Inc.

5. Psychological and Perceptual Factors

a. Focused Intent (Attentional Control)

• Directing attention to the effect (e.g., moving an object explosively) rather than internal cues enhances motor output.

• Reference: Wulf, G., et al. (2007). Attentional focus and motor learning. Journal of Motor Behavior.

b. Relaxation-Activation Cycling

• Alternating relaxation and sudden activation (seen in elite strikers, sprinters) produces whip-like efficiency.

• Reference: Ikai, M., & Steinhaus, A. H. (1961). Some factors modifying the expression of human strength. Journal of Applied Physiology.

6. Training Methods to Maximize Efficiency

• Heavy-Load Training: Builds maximal strength foundation.

• Ballistic & Plyometric Training: Develops RFD and SSC utilization.

• Rotational Power Drills: Medicine ball throws, cable twists.

• Technical Drills: Refine kinetic chain and alignment (sport-specific).

• Breathing & Bracing: Diaphragmatic breathing, powerlifting bracing.

Key Takeaway

Efficient force and power generation depends on ground-up kinetic transfer, neuromuscular synchronization, and optimized tissue mechanics. The most effective systems—whether in martial arts, athletics, or strength sports—blend structural alignment, elastic recoil, rotational dynamics, and mental focus.

Power and Force vs. Strength

Power, force, and strength are interrelated but distinct concepts in human performance, each defined by different mechanical and physiological characteristics. Understanding their differences is crucial for training, biomechanics, and applied performance.

1. Force

Definition:

• Force is the push or pull exerted on an object, measured in Newtons (N).

• In human movement, force represents the magnitude of muscular effort applied to overcome resistance.

Key Features:

• Determined by mass × acceleration (Newton’s Second Law).

• Can be isometric (no movement), concentric (shortening contraction), or eccentric (lengthening contraction).

• Not time-dependent; it describes how much effort is applied, not how quickly.

Example:

• A powerlifter producing 3000 N to hold a heavy barbell in place.

Reference:

• Enoka, R. M. (2015). Neuromechanics of Human Movement. Human Kinetics.

2. Strength

Definition:

• Strength is the maximal force a muscle or group of muscles can produce against resistance, regardless of time.

• Usually measured as 1-repetition maximum (1RM) or maximum voluntary contraction.

Key Features:

• Dependent on muscle cross-sectional area, neural recruitment, and leverage.

• Strong individuals can produce more total force, but not necessarily quickly.

Example:

• Bench pressing the heaviest weight you can move once, regardless of speed.

Reference:

• Zatsiorsky, V. M., & Kraemer, W. J. (2006). Science and Practice of Strength Training. Human Kinetics.

3. Power

Definition:

• Power is force × velocity, representing how quickly force can be applied.

• Measured in Watts (W).

Key Features:

• Relies on both force production (strength) and movement speed (velocity).

• More task-specific than strength; critical for athletic and combative performance.

• Uses Rate of Force Development (RFD) as a key determinant.

Example:

• A sprinter explosively pushing off the blocks or a martial artist delivering a knockout punch.

Reference:

• Aagaard, P., & Andersen, J. L. (2010). Effects of strength training on endurance capacity in top-level endurance athletes. Scandinavian Journal of Medicine & Science in Sports.

5. Practical Implications

• Strength training increases potential for both force and power by raising maximal force capacity.

• Power training (e.g., plyometrics, Olympic lifts) teaches the nervous system to express force quickly.

• Martial artists, sprinters, and field athletes often prioritize power over pure strength, whereas powerlifters prioritize strength.

Reference:

• Komi, P. V. (2003). Strength and Power in Sport. Blackwell Science.