What is it:
Tendons are tough, fibrous connective tissues that connect muscles to bones. They transfer force and store elastic energy, making movements smooth and efficient. Tendons have quite remarkable structures: they're stretchier at the junction to the muscle and stiffer at the junction to the bone. This makes sense because one of the materials (muscle) is soft, and the other is hard (bone). But it can also become a weak point in our musculoskeletal structure. Although tendons are highly resistant to tearing, they can get injured when stretched beyond their capacity or overused.
Tendon injuries usually happen at a rapid change in acceleration (called 'jerk'), such as when hitting a tennis or golf ball, especially without a proper warm-up, or when repetitively overloading the same muscles and tendons for days and weeks. Stiffer tendons produce better strength, power, and speed, which many activities require. However, a fine line exists between too stiff and not stiff enough. When tendon stiffness surpasses the muscle's ability to resist, an athlete has a higher chance of pulling a muscle. Men generally have stiffer tendons than women because of differences in sex hormones, especially estrogen. Exercise is the best way to increase the stiffness and health of your tendons.
The most common tendon disorders include:
Strains: occurs when you twist or pull a tendon beyond its capacity.
Tears: refers to tiny tears in the tissue in and around the tendon caused by a muscle's inability to absorb shock, load, and/or force optimally.
Tendonitis: results when your tendons become inflamed, usually due to repetitive activities, overuse, or aging (tennis elbow, jumper's knee, etc.).
Tenosynovitis: occurs when tendinitis combines with inflammation of the tendon sheath.
Tendinosis: occurs when collagen in your tendons has accumulated many torn fibers within the tendon. It is a chronic condition that weakens the tendon and deteriorates the structure of the tendon.
Purported Claims:
Scientific research highlights several types of exercises that can be particularly effective in strengthening tendons.
Eccentric Exercises
Isometric Exercises
Slow and Heavy Lifting
Plyometric Training
Progressive Loading
Balancing Flexibility and Strength
What the science says:
A tendon's outer layers have a remarkable ability to adapt with exercise. Tendons respond to resistance training by increasing the total number of collagen fibrils, increasing the diameter of collagen fibrils, and increasing fibril packing density. The tendon core, however, is formed during height growth and has a very poor turnover thereafter. Many studies suggest that eccentric exercises where the muscle is lengthening under tension, such as in eccentric hamstring curls or the lowering phase of a bicep curl, can stimulate collagen production and improve tendon strength and resilience. The Achilles tendon, which connects the calf muscle to the heel, is one of sports' most common tendon injuries. A 7-week study where male participants concluded 18 eccentric strength training sessions found that muscle thickness and fascicle angle increased at rest and during contraction, and the Achilles tendon stiffness increased. Most studies are quick to note that for tendon stiffness to improve significantly, the load has to be relatively high.
Isometric exercises where the muscle is contracting without changing its length such as planks or wall sits can help improve tendon stiffness, stability, and endurance. Isometric exercises and slow, heavy lifting could be especially effective if an athlete has a history of non-contact muscle pulls or is coming back from a tendon injury and there is pain associated with movement.
About 80% of tendons are comprised of collagen. The stiffer the tendon, the more crosslinks there are between collagen molecules. Exercise regulates crosslinking by physically breaking these attachments and then rebuilding them. Slow and heavy lifting has been shown to induce more breaking and rebuilding than fast movements. A study published in the Journal of Applied Physiology found that 12 weeks (4 days/week) of unilateral knee extension at 70% of maximal voluntary isometric contraction for 20 seconds per set (4 sets/day) increased the stiffness of tendon structures and the rate of torque production while shortening the electromechanical delay.
Fast movements such as plyometrics that use the tendon recoil response can enhance muscle-tendon properties and contribute to better tendon function as well as speed, power, and agility during dynamic movements. A Japanese study found that jump performances and ankle joint stiffness significantly increased after 12 weeks of plyometric training. Another study demonstrated that musculotendinous stiffness in the ankle joint increased after 6 weeks of plyometric training, contributing to improvements in running economy and 3 km running performance. The drawback of plyometrics is that it can be very intense and if done too much, can create more mechanical damage to tendons and other tissues. To optimize adaptations while minimizing fatigue and undue stress, research shows that short, infrequent loading bouts are optimal for improving engineered tendon and ligament physiology.
Progressive loading programs, such as gradually increasing weights in resistance training or adding resistance bands to movements, can stimulate tendon growth and improve overall tendon health. Some studies have found the progressive loading protocol to be more effective than the eccentric loading protocol in getting patients back to sports after patellar tendinopathy. A randomized clinical study also found that the symptom severity score was significantly lower in the progressive loading program group compared to the eccentric group after 24 weeks of training.
Maintaining a balance between flexibility and strength, e.g. scheduling yoga or dynamic stretching exercises before or on alternative days from strength-building exercises, is important to maintain optimal tendon health. Too much strength without adequate flexibility diminishes the range of motion and could increase the injury risk, especially in activities/sports that require bouncing and jumping with a high intensity of stretch-shortening cycles (SSCs). Recent studies have shown that stretching programs can significantly influence the viscosity of the tendon and make it significantly more compliant, and when a sport demands SSCs of high intensity, stretching may be important for injury prevention. However, there are many conflicting studies on stretching and its ability to prevent tendon injuries. The current conjecture states that when the type of sports activity contains low-intensity, or limited SSCs (e.g. jogging, cycling, and swimming) there is no need for a very compliant muscle-tendon unit since most of its power generation is a consequence of active muscle work that is directly transferred by the tendon to generate motion, therefore a need for a comprehensive stretching protocol is less important than in high-intensity sports.
Our take:
The exercises and strategies above, combined with adequate rest and recovery, form a comprehensive approach to strengthening tendons and improving overall musculoskeletal health. It's important to note that individual needs and goals are incorporated when we design your training program. Everyone's tendon health program needs to be personalized based on their genetics, medical history (i.e., injuries), and physical activity goals. Our experts at Apeiron Life will provide personalized guidance regarding your tendon health.
Will this benefit you?
Improving tendon health is a crucial aspect of overall fitness and well-being, and exercise can play a transformative role in enhancing tendon health. From strengthening collagen fibers to promoting better blood flow, the benefits of exercise extend beyond muscle development to include the resilience and longevity of our tendons. As people get older, tendons become thin, receive less blood flow than during our prime years, and accumulate microscopic damage to fibers that weaken the tendon. It is always a good idea to take care of your tendons along with your muscles even before you start having issues.
If you're still curious, here's what to keep an eye on:
A proper form is always important regardless of the exercise type since incorrect movement patterns or overloading can strain tendons and lead to injuries. Special attention should be given to warm-up, especially if you're planning on doing high-intensity plyometrics or heavy lifting. Tendons don't have as much blood flow and aren't as pliable as muscles so they take more time to be ready for high-intensity action.
References and further reading:
Comments