Strength Training: Understanding Exercises with an Ascending Strength Curve

What exercises have an ascending strength curve?

Exercises with an ascending strength curve are those where the biomechanical leverage improves throughout the concentric (lifting) phase of the movement, meaning the resistance feels relatively easier as the joint approaches full extension or contraction, allowing the muscle to produce more force towards the end of the range of motion.

Understanding Strength Curves in Exercise

To effectively train and understand movement, it's crucial to grasp the concept of a "strength curve." A strength curve illustrates how the force a muscle or muscle group can produce varies throughout its full range of motion against a given resistance. This curve is influenced by factors like muscle length, joint angles, and the leverages involved in a specific exercise.

What is a Strength Curve? A strength curve maps the relationship between the amount of force a muscle can generate and the joint angle at which it's operating. Different exercises, due to their unique biomechanics, present different strength curves. Understanding these curves helps in optimizing exercise selection, load management, and the application of variable resistance.

Ascending Strength Curve Explained An ascending strength curve describes a scenario where the muscle's ability to produce force increases as the joint moves through the concentric phase, typically becoming strongest towards the end of the range of motion (e.g., near lockout in a press or full extension in a squat). This means the exercise feels progressively easier as you complete the lift, or more accurately, your body's mechanical advantage improves, allowing you to handle more resistance at the end of the movement than at the beginning.

Descending Strength Curve In contrast, a descending strength curve indicates that the muscle's force production capability decreases as the joint moves through the concentric phase. The exercise feels hardest at the end of the movement, where leverage is poorest. An example might be the top of a dumbbell lateral raise, where the lever arm is longest.

Bell-Shaped Strength Curve A bell-shaped curve signifies that the muscle is strongest in the mid-range of the movement, with force production decreasing at both the beginning and end of the concentric phase. Many bicep curls fall into this category, where the mid-point of the curl is often the strongest, and both the very bottom and very top feel weaker due to biomechanical limitations.

Characteristics of Exercises with an Ascending Strength Curve

Exercises with an ascending strength curve share common biomechanical traits that allow for greater force production as the movement progresses.

• Improving Leverage: As the joint angle changes throughout the concentric phase, the involved muscles gain a better mechanical advantage over the external resistance. This often means the lever arm of the resistance decreases relative to the joint, or the muscle's line of pull becomes more efficient.
• Peak Strength at Lockout or Full Contraction: For exercises with an ascending curve, the point of maximal force output typically occurs near the end of the concentric phase, where the muscle is fully shortened or the joint is nearing full extension.
• Common in Pushing Movements: Many pushing exercises, particularly those involving compound movements, exhibit an ascending strength curve due to the improving leverage as joints extend.

Key Exercises Exhibiting an Ascending Strength Curve

Many foundational strength exercises, particularly those involving pushing or full body extension, demonstrate an ascending strength curve.

Pushing Movements

• Barbell Back Squat: The squat is a prime example. While the bottom position is often the most challenging due to deep hip and knee flexion, as you ascend, leverage improves significantly. You are strongest at the top, able to handle the most weight when standing upright and reaching full knee and hip extension.
• Barbell Bench Press: The bench press feels hardest off the chest (the bottom of the movement). As the bar moves upwards and the elbows extend, the triceps and chest gain better leverage, making the lockout phase the strongest point. This is why many lifters "stick" at the bottom but can complete the press once past that point.
• Overhead Press (Standing or Seated): Similar to the bench press, the overhead press is most challenging at the bottom (shoulders externally rotated, elbows tucked). As the bar is pressed overhead and the arms extend, leverage improves, making the lockout the strongest position.
• Leg Press: The leg press machine provides a clear ascending curve. The deepest part of the movement (knees bent) is the most challenging, but as the legs extend, the mechanical advantage improves, making the lockout phase the strongest.
• Triceps Pushdowns/Extensions: Whether using a cable or dumbbells, triceps exercises where the elbow extends often have an ascending curve. The triceps are most efficient and powerful near full elbow extension.

Pulling Movements

While less common for pure ascending curves compared to pushing movements (many pulling movements are bell-shaped or descending for specific muscles), some exhibit this characteristic, especially for the overall movement.

• Conventional/Sumo Deadlift: The deadlift is arguably the quintessential ascending strength curve exercise. The initial pull off the floor (breaking inertia) is the hardest part. As the bar ascends and the hips extend, the lifter gains significant leverage, making the lockout (standing tall with hips and knees extended) the strongest position. This is why lifters can often "hitch" or grind through the top portion even with maximal loads.
• Calf Raises (Standing/Seated): In a calf raise, the bottom position (ankles dorsiflexed) is where the Achilles tendon is most stretched and leverage is less favorable. As you push up into plantarflexion, the gastrocnemius and soleus muscles gain better leverage, making the very top of the movement (maximal heel elevation) the strongest point.
• Leg Extensions: Similar to triceps extensions, the quadriceps are strongest near full knee extension in a leg extension machine.

Implications for Training and Programming

Understanding ascending strength curves has significant implications for optimizing training.

• Maximizing Overload at Peak Contraction: For exercises with an ascending curve, the muscle is strongest at the end range. To fully challenge the muscle throughout its entire range, especially where it's strongest, trainers often employ variable resistance training.
  • Resistance Bands: Attaching bands to a barbell (e.g., bench press, squat) adds increasing tension as the band stretches, matching the ascending strength curve. This ensures the muscle is maximally challenged even at its strongest point.
  • Chains: Similar to bands, chains are lifted off the floor as the bar ascends, progressively increasing the load and matching the improving leverage.
• Addressing Sticking Points: While the exercise overall has an ascending curve, the initial phase (the "sticking point") is still the most challenging. Techniques like partial reps (e.g., board presses in bench press) or pin squats can be used to specifically overload and strengthen these weakest ranges of motion, which then contributes to overall strength in the full movement.
• Safety and Load Management: Knowing that you are strongest at the lockout means you can potentially handle heavier loads for the full range of an ascending curve exercise, but you must be mindful of the initial, weaker phase. Proper warm-up, technique, and spotting are critical, especially when approaching maximal loads.

Conclusion

The concept of an ascending strength curve is fundamental to advanced strength training and biomechanics. By understanding that certain exercises allow our muscles to generate progressively more force as we move towards lockout or full contraction, we can strategically apply training principles to maximize muscle overload, improve performance, and overcome sticking points. Incorporating variable resistance tools like bands and chains, or specific partial range training, allows us to match the resistance to our body's changing strength throughout these powerful movements, leading to more comprehensive strength gains.