Biomechanics of Strength Training: Essential Physics for Performance and Power
- Daniel McKee
- May 6
- 4 min read
Updated: May 10
Understanding the Biomechanics of Strength Training is essential to effective training. Biomechanics is the bridge between physics and human movement. When applied to sports and strength training, it becomes a powerful tool for understanding how we produce strength, power, and display effective performance.
In other articles, I developed a complete categorization system for understanding human movement in training and sports, and I comprehensively defined strength and listed its various modalities.
The diagram above maps out the core concepts of the physics of strength training and conditioning, showing how they’re all interconnected. Let’s explore these relationships and why they matter in training.
1. Biomechanics of Strength Training: Mass Is the Foundation
The biomechanical conceptual chain begins with Mass — the amount of matter in an object (or an athlete). Mass is measured in Kilograms (or Pounds). It anchors two fundamental movement concepts:
Mass × Velocity = Momentum. Momentum is a measure of how hard it is to stop a moving object — in sport, it relates directly to the impact of a tackle, punch, or kick. Momentum is measured as kg * m/s.
Mass × Acceleration = Force. This is Newton’s Second Law. Force is the primary output of strength training — the raw capacity to move or resist movement. Strength is the ability to produce force, so understanding and training this relationship is central to athletic development. The Newton is the unit of Force.
Momentum 
Force
2. Acceleration and Velocity Come from Change Over Time
Velocity is a change in displacement over time. Velocity is measured in Meters Per Second (m/s).
Acceleration is a change in velocity over time. The measure of Acceleration is Meters Per Second squared (m/s²).
These “rate of change” values are vital to explosive movement.
We can classify strength capacities by the balance of force and velocity:
Speed Strength: Ability to move with high velocity while producing significant force (e.g., jump squats, medicine ball throws)
Strength Speed: Ability to produce high force at moderate-to-fast velocity (e.g., heavy power cleans)
Accelerating Strength: Rapid increase of force in the isometric phase — before a lift begins moving (critical for speed off the floor in deadlifts)
Acceleration Strength: Increasing force output during the concentric phase (e.g., the bar rising in a squat), enhanced with accommodating resistance like chains or bands.
3. Force × Displacement = Work
Once force is applied through a range of motion, work is done. In training, this refers to moving a weight through space — barbell × distance (e.g., squatting a load over a given ROM).
Work is the foundation of:
Fatigue (cumulative work leads to fatigue and adaptation)
Hypertrophy (protein degradation and remodeling correlate with total work performed at or above ~60% of 1RM)
Training volume, therefore, is best understood as the sum of biomechanical work — not just reps and sets. Work is the key element for calculating, prescribing, and regulating Loading from weight training.
The total Work done with over 60% (approx) intensity in a training unit determines the amount of protein degradation in the working muscles, which determines how much muscular growth will occur during the recovery phase.
Energy is the element that imbues a body with the ability to do Work. In another article, I discussed how our body produces, stores, and uses energy in training and sports.
4. Work ÷ Time = Power
Power is the rate at which work is done and is one of the most important attributes in sport. In activities like Olympic weightlifting, jumps, and sprints, success hinges not just on how much work is done but also on how quickly it's executed. The unit of Power is the Watt.
Olympic lifts are true power movements: the entire action happens in under a second. Due to their velocity component, the power output (Work ÷ Time) often exceeds the force applied.
Olympic lifts are essentially power-generating in their nature, while the movements of Powerlifting are primarily force-generating.
Power
5. Force × Time = Impulse
Impulse is the total force applied over a duration, and it's what changes momentum.
This principle is crucial in sports like:
Boxing (absorbing and directing strikes)
Football (braking and changing direction)
Powerlifting (applying force to overcome inertia)
Impulse explains why a longer, well-directed application of force can produce more change in momentum than a short, high-intensity burst.
6. Force Gives Rise to Torque, Stress, and Strain
Force has consequences — it produces rotational effects, tissue stress, and deformation:
Torque = Force × Moment Arm; this drives joint actions, especially important in squatting, pressing, and throwing. Understanding Torque is mandatory for mastering the function of the body's levers and muscle mechanics.
Torque 
Stress (physics) Strain is tissue Deformation caused by Stress. It represents a physical change, such as muscle elongation, tendon recoil, or fascial stretch.
Strain
Why It All Matters for Strength Training
Strength training is not about mindlessly lifting — it’s about producing force and power in a biomechanically efficient way. Applying these principles allows coaches and athletes to:
✅ Manage joint torque more safely (e.g., keeping the bar over mid-foot in a squat)
✅ Maximize work and power output for greater adaptation
✅ Reduce injury risk by understanding and distributing stress
✅ Improve movement mechanics, impulse control, and force development across sport contexts
Conclusion: Train Smart, Not Just Hard
Every effective training decision — from rep ranges to load prescription — is an application of biomechanics. This article provides a basic understanding of kinematics in sports performance. The rest of this blog series provides a comprehensive picture of holistic development and performance. The better we understand these forces and relationships, the more we can train with intent, adapt faster, and perform better. This is training NOT exercise.
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