Training Programs to Strengthen Tendons

Here are some ideas for exercising to strengthen tendons, summarized from Jake Turra’s Tendon Book.

Tendons must be trained in order for them to be able to continue carrying out their main functions, as discussed in Chapter 1: to “conserve energy, amplify power, transmit force, and buffer energy.” With training, tendons undergo several anatomical and physiological changes. For instance, more collagen is produced, collagen is arranged to more effectively manage stress, the cross-sectional area of the tendon increases, more cross-links between collagen molecules are created, and the gel is kept hydrated and fluid. Also, as a result of training, tendons become stiffer and thus energetically more efficient at handling strain, and less energy is dissipated as heat over time, allowing for more stored energy to be used for bodily movements. Each of these adaptive developments is reversed when a tendon is at complete rest for an extended period of time (e.g., bed rest), and the tendon breaks down.

Being active, as opposed to being at complete rest, is the most foundational and basic way to train tendons. Recall that tendons work by stressing and straining; simply walking around, standing and sitting, grabbing and reaching for things, and other daily movements strengthen the tendons. Stresses and strains alert the tendon cells to make more collagen. 

Sports and plyometrics training subject the tendons to much greater stresses and strains than general activity. That type of training can result in almost twice as much collagen synthesis. Many tendon adaptations can be caused by years of consistent participation in sports and plyos. For instance, runners have a thicker Achilles tendon, soccer players have a stiffer Achilles tendon, and sprinters and jumps have thicker hamstring tendons. These changes take place because of the Specific Adaptation to Imposed Demands (SAID) principle. As more stress and strain is placed on tendons, they adapt to better handle those stimuli. The effect of tendon training with sports and plyometrics is optimized when using “multi-effort, medium intensity” exercises. Highly intense movements that can only be performed once do not subject the tendon to enough volume to trigger adaptations. Low intensity movements do not impose enough stress/strain. 

Heavy, slow resistance (HSR) training is another great way to develop the tendons. Long duration strains and stresses provide an optimal stimulus for triggering tendon adaptation. This is because, during a strain, the gel and collagen are stretched, but the cells are not. As the strain is extended, though, the tendon cells are signaled to produce collagen, elastin, GAGs, and other tendon materials via mechanotransduction. For HSR training to effectively train the tendons, heavy resistance must be used so that a high amount of muscle force is produced to pull on the tendons. A “heavy enough” load is typically defined as 70% of an individual’s 1RM. Also, the strain must be long lasting–as in slow movements–so that the mechanical signal reaches the cells (during slow strains, the tendon acts viscously to dissipate energy, such that the gel, fascicles, and fibrils move around). Research suggest that a muscle contraction must be held for at least three seconds to stimulate cell mechanotransduction.

Training protocols have been developed specifically to train tendons. The Kongsgaard Protocol utilizes leg presses, squats, and hack squats–all three involving a 3-second eccentric and 3-second concentric phase. This 12-week program includes 4 sets, 2-3 minutes rest, and decreasing rep amounts, from 15 RM on Week 1 to 6 RM during the last week. The high rep amounts with slow phases may make it difficult to lift heavy loads, so instead you may use a heavy weight that will automatically move slowly, or lower the reps or break them into clusters. 

The Berlin Method includes just two exercises: straight-leg calf 3 second isometric hold with a neutral ankle (for the achilles), and knee extension 3 second isometric hold at 60 degree knee flexion (for the patellar). These are completed at 5 sets of 4 reps at 90% of max effort with 1 minute rest.