The Science behind the Swing

Although this page is developed with the baseball swing in mind, the same exact principles and philosophies apply to the golf swing.

At Fourteen23 Fitness, our mission isn’t just to tell you what to do — we want to show you why it matters. This isn’t a generic list of drills or a one-size-fits-all training plan. This is the science behind the swing, broken down with transparency, intent, and real-world application. Every recommendation we make is rooted in biomechanics, physiology, and proven performance principles — so you’re not just following instructions, you’re understanding the logic behind them. We believe athletes perform better when they know the why behind their work—and this page is built to give you exactly that.

Here, we’ll dissect the origins of rotational power and movement efficiency. You’ll learn where energy is generated in the swing, how it builds through the kinetic chain, and where it can leak or amplify. We highlight the key physical checkpoints that matter most — lower body force production, rotational sequencing, spinal leverage, and fast-twitch muscle recruitment — and explain how each contributes to speed and power. Most importantly, we’ll show you how to target these areas directly in your training so you’re not just swinging harder, you’re swinging smarter.

Kinematic Sequence

The baseball swing is a rotational chain reaction that starts from the ground up. It’s not just about having a strong upper body—it’s about how efficiently each segment of the body contributes to the swing in the right order. This efficient transfer of energy through the legs, hips, torso, arms, and bat is called the kinematic sequence. The hips initiate the swing, followed by the torso, then the lead arm, and finally the bat. This progressive build-up of velocity through each segment allows for explosive bat speed with minimal wasted movement—and is the foundation of elite hitting mechanics.

  • Power starts from the ground, and so does the proper kinematic sequence.
  • Following the rotation of the hips, the torso builds on this rotation and adds to it.
    • The absolute angular velocity of the torso is the absolute angular velocity of the hips + the angular velocity of the torso relative to the hips.
  • After the torso has began rotating, the lead arm begins and adds onto the angular velocity of the torso.
    • The absolute angular velocity of the lead arm is the absolute angular velocity of the torso + the angular velocity of the lead arm relative to the torso.
  • The last piece of the kinetic chain, the bat/club fires last and adds on to the angular velocity of the lead arm.
    • The absolute angular velocity of the bat/club is the absolute angular velocity of the lead arm + the angular velocity of the bat/club relative to the lead arm.

In rotational sports, absolute velocity is the total speed of a segment relative to the ground—while relative velocity is how fast that segment is moving compared to the part below it. Each joint or segment in the kinetic chain builds on the speed generated by the one before it. The faster and more efficiently a lower segment rotates, the more potential the next segment has to generate even greater absolute velocity. That’s why sequencing matters: power isn’t just about how fast one part moves, but how well that speed stacks through the chain.

Ground Reaction Forces

Ground reaction forces (GRFs) are the foundation of power in the baseball swing. Every explosive move at the plate starts with your interaction with the ground. As a hitter loads, strides, and rotates, they apply force into the ground—and the ground pushes back. That equal and opposite force creates the stability and energy needed to drive rotation and transfer power up the chain. While most hitters think about their hands or hips, elite hitters know that real power starts in the feet. GRFs come in three directions—horizontal, torque (rotational), and vertical—and each plays a distinct role in the swing sequence.

Horizontal ground forces come into play during the load. As the hitter coils into the back leg and prepares to stride, a horizontal push into the ground helps anchor the back foot and shift pressure into the rear hip. This force—often felt as a subtle “dig” or “bracing” into the back leg—creates the foundation to store energy during the coil. Without proper horizontal loading, hitters tend to drift or lose posture, making it harder to sequence and create stretch through the torso.

Torque (rotational) ground forces occur during the transition—when the stride foot lands and the hips begin to fire while the upper body stays loaded. At this moment, the feet apply shearing forces in opposite directions—the back foot rotates inward while the front foot resists or slightly rotates outward. This action creates hip–shoulder separation and builds elastic tension through the core. It’s how hitters generate torque from the ground instead of forcing rotation from the top.

Vertical ground forces are expressed just before and through contact. As the front foot plants firmly, the hitter drives upward into the ground. This vertical push helps the lead leg brace and the front hip clear, translating all stored rotational energy into bat speed. The more vertical force a hitter can apply at the right time, the more efficiently they can accelerate the bat through the zone and deliver a powerful strike.

Muscle Fiber Types & Their Role

Slow-Twitch (Type I) Muscle Fibers

The Foundation of Stability, Control & Endurance.

Slow-twitch fibers are the workhorses of control and consistency. They contract at a slower rate than fast-twitch fibers but are highly resistant to fatigue, making them essential for movements that require postural stability, fine motor control, and sustained output over time. In rotational sports like baseball and golf, they help anchor your body during load and transition phases, providing the stable platform needed for efficient sequencing.

Whether you're holding your posture through the stride phase of a swing or maintaining form during a long round or game, your Type I fibers are doing the behind-the-scenes work—quietly keeping your body aligned, balanced, and ready to transfer energy. These fibers are critical for making your explosive movements repeatable, consistent, and clean.

Training for Slow-Twitch Development:

  • Tempo-Based Strength Work – Slower eccentrics (3–5 seconds down) and controlled concentrics build control under load.
  • Isometric Holds – Pauses at key positions (like the bottom of a split squat or RDL) strengthen positional endurance.
  • Higher-Rep, Submaximal Controlled Sets – Loads around 50–70% of max for 10–20 reps target muscular endurance and control.

Benefits for Rotational Athletes:

  • Enhances balance and posture under fatigue
  • Improves control during load-stride-sequence phases
  • Builds the platform for efficient energy transfer
  • Supports endurance through high-volume swings or extended play

Fast-Twitch (Type II) Muscle Fibers

The Engine of Explosive Speed & Rotational Power

Fast-twitch fibers are your body’s power generators. These fibers contract rapidly and with force, allowing you to accelerate the bat or club, rotate explosively through the hips and torso, and generate elite-level velocity at impact. They are essential for single, high-intensity movements—like a swing, sprint, or throw—and are the key to maximizing your rate of force development (RFD).

Fast-twitch development isn’t just about going heavy—it’s about moving with intent and explosiveness. These fibers respond best to high neural demand, meaning your nervous system must be primed to fire them fast and efficiently. That’s why fast-twitch training often looks like a mix of maximal strength work and explosive plyometrics or med ball throws.


Training for Fast-Twitch Development:

  • Heavy Compound Lifts – Low-rep deadlifts, squats, and presses (85–95% 1RM) increase overall force potential.
  • Dynamic Effort Lifts <– Lighter loads moved with speed teach the nervous system to recruit fast-twitch units quickly./li>
  • Explosive Movements – Jumps, sprints, slams, and rotational throws develop speed, power, and sequencing under velocity.

Benefits for Rotational Athletes:

  • Drives bat speed or clubhead velocity through fast rotation
  • Improves explosiveness out of the load and through impact
  • Enhances ability to create force in short time windows (critical in reactive sports)
  • Sharpens neuromuscular coordination and intent

Not Just Strong, but Mobile


Strength alone doesn’t produce elite swing power—mobility is what allows your body to use that strength effectively. It’s not just about how much force your muscles can generate, but whether your joints allow you to get into the right positions to transfer and unleash that force. In a baseball swing, power is built from the ground up and transferred through a complex chain of motion. Without functional mobility, that chain breaks down—and with it, your ability to hit with speed, consistency, and power.

Key areas like the ankles, hips, thoracic spine, and shoulders all need sufficient mobility for proper loading, sequencing, and rotation. For example, a right-handed hitter must internally rotate into the back (right) hip during the load, externally rotate into the front (left) hip during the stride and rotate freely through the T-spine at contact. Limitations in these areas lead to compensations—like over-rotating the lumbar spine or lunging forward—which reduce bat speed and increase injury risk.

Mobility isn’t just flexibility—it’s controlled range of motion under tension. It’s the ability to coil deeply into the back leg and uncoil explosively into impact without losing balance or posture. The best hitters don’t just swing hard—they move well. They access deep positions with stability, maintain separation between the upper and lower body, and time everything in sync.

Strength training is critical—but without mobility, you’re limiting your swing potential. If you want to unlock real power at the plate, mobility must be part of your preparation. When your joints can move the way they’re designed to, your body can load better, rotate faster, and hit harder—with less effort and more efficiency.

Loading the Back Leg

Proper ankle & hip mobility required to effectively load the back leg without swaying.

Stride & Firing Hips

To get into an effective stride position and to fire your hips properly, sufficient mobility is required in the ankles, hips, torso, shoulders, elbows, wrist, neck, etc

Impact

Even at impact, the proper mobility is required to get into position including but not limted to in the shoulders, elbows, hips, ankles, etc.

At F23 Torque, We Train for P.E.A.K Performance