From the Guidelines
Eccentric contractions involving muscles and tendons occur when a muscle lengthens while under tension, essentially working to slow down or control a movement rather than generate it. During an eccentric contraction, the muscle-tendon unit is actively resisting an external force while simultaneously elongating. Common examples include the lowering phase of a bicep curl, walking downhill, or the downward motion of a squat. These contractions place unique stress on muscles and tendons because they generate greater force than concentric (shortening) contractions while requiring less energy. Eccentric loading is particularly important in rehabilitation settings because it strengthens tendons by stimulating collagen production and improving tissue alignment, as noted in the context of flywheel resistance training 1. This type of contraction also causes more microscopic muscle damage than other contraction types, which explains why activities with significant eccentric components (like downhill running) often lead to greater muscle soreness. The body adapts to eccentric training over time, resulting in increased strength and reduced injury risk, making eccentric exercises valuable components of both athletic training and physical therapy programs. Key benefits of eccentric contractions include:
- Increased strength
- Reduced injury risk
- Improved tendon health through stimulation of collagen production and tissue alignment
- Enhanced muscle function and overall athletic performance As supported by recent guidelines, eccentric strengthening is an effective treatment for tendinopathy and may reverse degenerative changes 1. Therefore, eccentric contractions should be a prioritized component of training and rehabilitation programs to maximize benefits for muscle and tendon health, as well as overall athletic performance and injury prevention.
From the Research
Eccentric Contractions Involving Muscles and Tendons
Eccentric contractions occur when activated muscles are forcibly lengthened, resulting in high forces being produced despite low energetic costs 2. This type of contraction is essential for dissipating energy and decelerating the body, as well as storing elastic recoil energy in preparation for shortening contractions 3.
Characteristics of Eccentric Contractions
- Eccentric contractions can maximize force exerted and work performed by muscle 2
- They are associated with greater mechanical efficiency and can attenuate mechanical effects of impact forces 2
- Eccentric contractions can lead to muscle damage, characterized by a rise in whole-muscle passive tension 4, 5
- Tendon organs can monitor passive tension changes in the muscle, indicating muscle damage produced by eccentric contractions 5
Muscle and Tendon Adaptation
- The muscle-tendon system can adapt to progressively increasing eccentric muscle forces, resulting in structural and functional changes 3
- Muscle hypertrophy and changes in spring characteristics can enhance power, while tendon adaptation can tolerate higher tensions 3
- Eccentric exercises can be used as a treatment for various muscle and tendon injuries, with implications for rehabilitation 6