3.2 Contraction Type: Eccentrics and Concentrics

In hypertrophy training, the type of muscle contraction you perform can influence the growth stimulus. The three main types of contractions are:

• Concentric: The muscle shortens as it contracts (e.g., the upward phase of a biceps curl).
• Eccentric: The muscle lengthens while contracting (e.g., the downward phase of a biceps curl).
• Isometric: The muscle contracts without changing length (e.g., holding a plank position).

For all practical purposes, we are going to focus on concentric and eccentric contractions, as they are the most relevant for hypertrophy training (even though isometrics have applications and are known to cause hypertrophy as well).

The concentric is the most prolific contraction type for hypertrophy, however one might have an interest in emphasizing eccentrics for various reasons:

• Less chance of injury: this is especially true for exercises that heavily load the muscle in a stretched position, such as a SLDL or a Pec Fly
• Better concentric performance: a badly executed eccentric can impair the subsequent concentric, therefore emphasizing the eccentric can be a good way to ensure the concentric is performed with good form and maximal tension
• Passive tension: as discussed in the previous section, eccentric contractions can generate more passive tension, which may provide a unique hypertrophic stimulus through SMH (Stretch-Mediated Hypertrophy)
• Tendons and connective tissue: eccentric training is known to be particularly effective for strengthening tendons and connective tissue, which can improve overall joint health and reduce injury risk

It’s also worth noting that prolonging the eccentric phase can lead to increased muscle damage and soreness, which may require longer recovery times. Therefore, it’s important to balance eccentric emphasis with overall training volume and recovery needs.