Strength Training: Understanding Slack, Its Impact, and How to Eliminate It

What is Slack in Lifting?

In the context of strength training, "slack" refers to any looseness or un-tensioned play within the lifting system—comprising the lifter's body, the equipment, and the load—that exists before the full force of the lift is applied.

Understanding "Slack" in the Lifting Context

From a biomechanical perspective, successful lifting is about creating an efficient and stable system to transfer force from the lifter's muscles to the external load. "Slack" represents a lack of this optimal tension and connection. It's the momentary "give" or "jerk" that occurs at the beginning of a lift when the lifter's body or the equipment isn't fully taut and ready to bear the load.

Consider a chain: if there's slack in the chain, you must first take up that slack before you can effectively pull the object. Similarly, in lifting, any slack means that the initial movement phase is spent taking up this looseness rather than directly applying force to move the weight.

The Mechanics of Slack

Slack manifests differently across various exercises but always involves a lack of pre-tension.

• Barbell Lifts (e.g., Deadlift, Bench Press, Overhead Press): This is perhaps the most common context. Before the bar leaves the floor in a deadlift, or before it moves off the pins in a rack pull, there might be a slight upward movement of the bar within the plates, or a slight bend in the bar itself, before the full weight is lifted. This is bar slack. Additionally, if the lifter's body isn't rigid, there can be slack in the joints or musculature.
• Kettlebell Swings: At the bottom of the swing, before the powerful hip drive, if the lifter's arms are completely relaxed and the kettlebell is "floating," there's slack. The arms must become taut, connecting the bell to the hips, before the explosive extension.
• Pulling Exercises (e.g., Pull-ups, Lat Pulldowns): Before initiating the concentric phase, if the shoulders are shrugged up or the arms are completely relaxed, there's slack. The lats and shoulders should be engaged to create tension before the pull.
• Machine-Based Exercises: Even on machines, there can be slack if the initial movement involves the weights clanking together or the cables becoming taut before the resistance is fully felt.

Why does it occur? Slack primarily occurs due to gravity and the inherent design of equipment (e.g., the slight play between a barbell sleeve and the plates, or the stretch in a cable). More importantly, it occurs when a lifter does not actively create tension throughout their body and the implement before initiating the primary movement. This pre-tensioning is a critical skill.

The Impact of Slack on Performance and Safety

Ignoring or failing to manage slack has significant implications for both the effectiveness and safety of a lift.

Potential Benefits of Managing Slack:

• Improved Force Transmission: By eliminating slack, the lifter creates a rigid, stable system. This allows for more direct and efficient transfer of force from the muscles through the skeletal system to the external load. Every ounce of effort contributes directly to moving the weight.
• Enhanced Stability and Control: A pre-tensioned system is inherently more stable. This reduces unwanted movement, improves balance, and allows for greater control over the weight throughout the entire range of motion.
• Reduced Injury Risk: Jerking or yanking the weight to overcome slack can place sudden, high-impact stress on joints, ligaments, and tendons. By smoothly taking out the slack, the load is progressively and safely engaged, distributing stress more evenly and reducing peak forces on vulnerable structures.
• Greater Neuromuscular Readiness: Taking the slack out cues the nervous system to prepare the relevant muscles for the upcoming load. This pre-activation leads to more effective motor unit recruitment and a stronger, more controlled lift.

Potential Risks of Ignoring Slack:

• Energy Leaks: Any movement spent taking up slack is wasted energy that could have been used to lift the weight. This makes the lift less efficient and limits the amount of weight that can be moved effectively.
• Loss of Position: A sudden jerk to overcome slack can pull the lifter out of their optimal starting position, compromising technique and increasing the risk of injury.
• Increased Shear Forces: In lifts like the deadlift, jerking the bar off the floor due to slack can introduce excessive shear forces on the lumbar spine, a common mechanism for back injuries.
• Suboptimal Muscle Activation: Without proper pre-tension, the primary movers may not be fully engaged from the start, leading to compensatory movements from less efficient or more vulnerable muscle groups.

How to "Take the Slack Out"

The concept of "taking the slack out" is a crucial cue for many advanced lifters and involves actively creating tension throughout the system before the main lift phase.

General Technique Cues:

• "Feel the Weight": Before the lift, gently pull or push on the bar until you "feel" the full weight of the load in your hands, feet, or through your body, even if the weight hasn't moved yet.
• "Tension the Bar": Imagine trying to bend the bar (e.g., pulling it apart for a bench press, or bending it upwards for a deadlift) without actually moving it. This activates the lats and creates rigidity.
• "Brace and Engage": Fully brace your core, engage your lats, and set your shoulders and hips into their optimal starting position before initiating the movement.
• "Pre-Load": In some cases, it involves a slight pre-tensioning movement, like gently pulling on the deadlift bar until you feel your hamstrings and lats engage, just before the full pull.

Application to Specific Lifts:

• Deadlift: From the setup, grip the bar and pull upwards gently, just enough to hear the plates clink and feel your lats and hamstrings load up. Imagine pulling the slack out of the bar, making it "light" in your hands, before your hips and shoulders move upwards. This ensures the entire system is rigid and ready.
• Bench Press: Once unracked, pull the bar down into the uprights of the rack (or imagine pulling it apart) and squeeze your lats. This creates tension across your upper back and shoulders, ensuring a stable base before the descent.
• Overhead Press: When unracking, ensure your core is braced and your lats are tight, creating a stable platform for the bar. Don't just push the bar up; drive it up from a fully tensioned position.
• Pull-ups/Lat Pulldowns: Before pulling, depress your scapulae and engage your lats. Imagine pulling your shoulders away from your ears, creating tension in your upper back before you initiate the arm pull.

Scientific Rationale and Biomechanical Principles

The practice of taking the slack out is rooted in fundamental biomechanical and physiological principles:

• Neuromuscular Readiness: By creating pre-tension, you are effectively "waking up" and pre-activating the motor units in the muscles required for the lift. This allows for a more synchronous and powerful contraction from the very beginning of the concentric phase. It enhances proprioception—your body's awareness of its position and movement—allowing for better control.
• Kinetic Chain Efficiency: The human body is a kinetic chain. Any looseness or "slack" in one link compromises the efficiency of force transfer throughout the entire chain. By removing slack, you create a rigid, integrated system where forces can be transmitted optimally from the ground up (or from the core outwards) to the external load.
• Joint Stability: A pre-tensioned muscle creates a more stable joint. For example, engaging the lats and bracing the core in a deadlift helps to stabilize the spine and shoulders, protecting them from excessive movement or sudden loading. This "joint packing" reduces the risk of injury.
• Stretch-Shortening Cycle Optimization (for some lifts): While the primary goal is pre-tension, in some dynamic lifts, taking the slack out can also set the muscles in a more optimal position to benefit from the stretch-shortening cycle, allowing for a more powerful concentric contraction.

Conclusion: Mastering the Unseen Force

"Slack" is an invisible force that can undermine your lifting performance and increase injury risk. Mastering the skill of "taking the slack out" is not merely a technique cue; it's a fundamental principle of efficient and safe strength training. By consciously creating tension throughout your body and the equipment before initiating a lift, you transform a potentially unstable and inefficient system into a powerful, controlled, and injury-resilient force delivery mechanism. Incorporating this practice into your training will lead to stronger, safer, and more effective lifts across the board.