Eccentric training is a superior form of training that will pay off with more strength and less injury risk. It’s also a great way of injecting variety into your training to keep you from getting bored.
Extensive research shows that eccentric training improves connective tissue strength (especially tendon strength) because it promotes collagen production. Remember that tendons have a slow metabolic rate with limited blood supply, making them very slow to heal. Eccentric movements will stimulate blood flow, promote tendon healing, and activate mechanoreceptors in the cells of the tendon, increasing tendon strength.
Eccentrics will also lengthen the muscle-tendon unit, increasing range of motion (ROM) or flexibility around a joint. For example, eccentric training is commonly used to rehabilitate, strengthen, and lengthen the Achilles tendon.
Authors suggest a minimum of 12 weeks of eccentric training for tendon remodeling and regeneration. Three sets of 15 reps, with increasing repetitions are typically used in the literature. You can also progressively increase load and decrease reps as an individual progresses to restore tendon strength and joint function.
Eccentric training is also great for increasing flexibility by increasing the sarcomeres in series within the muscle. For example, at the hamstring, a 6-week eccentric program increased joint ROM increased by as much as 13 degrees. A 14-week eccentric training program increased hip ROM by an average of 22 percent.
Good news is that studies suggest the value of eccentric training can be seen in practice by keeping athletes healthier on the field. Two studies of elite soccer players showed that eccentric hamstring training dramatically decreased injury rates in the hamstrings.
There is no downside to including eccentric training in your program (besides soreness afterwards) since it will help you increase flexibility, while boosting tendon and muscle strength. If you are new to eccentric training, begin by manipulating tempo with a 4-second eccentric phase and a 1-second concentric phase. This can be varied to use a longer eccentric phase and an explosive concentric motion.