Patellar tendinopathy II. Role of eccentric training in treatment and prevention.

We define eccentric contraction as a muscle contraction in which the ends of the muscle move apart, overcome by an external force that exceeds the contractile force of the muscle itself. This type of contraction involves muscle tension and, at the same time, muscle fiber lengthening.

Pain relief achieved through eccentric training has been demonstrated exclusively in Achilles tendonitis, although excellent results have been obtained by applying eccentric training to other types of tendonitis, such as supraspinatus tendonitis or, in this case, patellar tendonitis.

Although there is no scientific evidence of the histological adaptations that eccentric training induces in the affected tendons, its benefits have been observed in the form of pain reduction, increased resistance, and decreased fragility and thinning.

Several hypotheses attempt to explain the benefits of eccentric training:

Tender thickness, with improved tensile capacity.
Tension reduction by lengthening the musculotendinous unit.
Collapse and disappearance of neovascularization and neoinnervation associated with tendinopathy, leading to pain reduction.

Treatment in the acute phase:
1.-Preconditioning: Cycling or non-impact exercise.
2.-Manual therapy:

• Quadriceps release massage.
• Patellar mobilization + tendon warm-up prior to the session or physical activity.
• Transverse and longitudinal tendon extensibility exercises in cases of paratendinous involvement.
• Active tension stretches of the quadriceps and posterior chain.

3.-Eccentric exercises: proven to be useful, eccentric exercise produces greater hypertrophy than concentric or isometric exercise.

• Protocol duration: 12 weeks. If the athlete is in the recovery phase, the protocol will be continued for 12 weeks from that point.
• Exercises should be performed twice a day, 7 days a week.
• 10 repetitions per set, for a total of 6 sets, performing the lowering (eccentric phase) on the affected leg or both legs, and the raising (concentric phase) on the healthy leg or both legs.
• Manual eccentric training: The athlete sits on a stretcher with his knee extended, maintaining an isometric quadriceps contraction. The therapist will flex the knee to generate an eccentric contraction. It is essential to respect the player's pain (exercise limit). 4 sets of 12 repetitions, alternating speed.

The tolerance of manual eccentric training will allow us to continue with the rest of the eccentric exercises detailed below:

1.-Eccentric training with a Russian belt or muscle strap: Perform a pain-free range of motion, with only the lowering (eccentric) phase held for 3-4 seconds.

2.-Eccentric training with a Russian belt or muscle strap: Identical to the previous exercise but with lowering and raising phases (at a faster speed than the lowering).

3.-Eccentric training with a Russian belt or muscle strap with electrostimulation: Exercise number 1 but with Quadriceps electrostimulation.

4.-Eccentric exercises with machines: knee extension, paying special attention to the eccentric phase. Can be performed with or without electrostimulation. Slowly lower the muscles and rapidly raise them.

5.-Eccentric exercises on an inclined plane: The athlete looks down the slope and performs a quarter-inch single-leg squat. The lowering phase is pain-free, maintaining a 15° flexion position for 3 to 4 seconds.

Eccentric exercises on an inclined plane with mechanical vibration.

Chronic phase treatment
Preconditioning: identical to that for the acute phase.
1.-Cycling or low-impact exercise.
2.-Manual therapy:

• Quadriceps release massage.
• Patella mobilization + tendon warm-up prior to the session or physical activity.
• Transverse and longitudinal tendon extensibility exercises in cases of paratendinous involvement.
• Active tension stretches of the quadriceps and posterior chain.

3.-Eccentric exercises:

• Work Manual eccentric: Athlete on a stretcher with the knee extended, maintaining isometric quadriceps contraction. The therapist will flex the knee to generate an eccentric contraction. It is essential to respect the player's pain (exercise limit). 4 sets of 15 repetitions alternating speed.
• The first sessions reproduce the exercises as explained for the acute phase (exercise 1), moving on to exercises 4, 5, and 6 before rehabilitation or return to activity.
• Electrotherapy is used after eccentric training sessions or at the end of the sports activity (galvanic currents, ultrasound, or tens combined with cryotherapy).

Prevention
There is scientific evidence showing that simultaneous strengthening and stretching of the musculoskeletal system is preventative for certain injury cases.

Some recommendations to prevent patellar tendinopathy in sports include:

• Biomechanical analysis of gait and running, and study of the knee's mechanical axis.
• Analysis of the footwear used by the athlete.
• Analysis of the surfaces on which activities are performed.
• Specific warm-ups prior to sessions, with special recommendations for active tension stretching at the beginning of the activity and passive stretching at the end.
• Eccentric exercise program for patellar tendinopathy twice a week. 6 sets of 10 repetitions with each leg (exercises 1 and 2).

Make an appointment with Dr. Jordi Jiménez. He will see you in the center of Palma and help you regain your quality of life.

Clinical practice guide for tendinopathy: diagnosis, treatment, and prevention.
FC Barcelona Medical Services.
Sports Medicine Notes. 2012;47(176):143-168