Achilles tendon

Discussion in 'Health and Fitness' started by john yates, Mar 26, 2006.

  1. john yates

    john yates Valued Member

    How can achilles tendinitis be prevented - or cured once it develops? Although everyone seems to agree that calf-muscle strength plays a key role in both the development and resolution of achilles tendon difficulties (functionally strong calf muscles should ease stress on the achilles, lowering the risk of injury or promoting healing), not a single scientific study has been published which actually links calf-strengthening with toughening of the achilles - until now

    That deficiency has fortunately been corrected, thanks to some recently published research carried out at the Sports Medicine Unit of the University Hospital of Northern Sweden in Umea, Sweden. There, investigators divided 30 athletes with chronic achilles tendinitis into two groups. One group of 15 received only traditional achilles tendinitis treatment (non-steroidal anti-inflammatory medications, rest, orthotics, shoe changes, cortisone injections, and physical therapy), while 15 others engaged in 'heavy-load eccentric calf-muscle training' (to be explained in a moment). All 30 subjects experienced morning stiffness in one of their achilles tendons (athletes with problems in both tendons were excluded from the study) and suffered from pain while running

    The heavy-load eccentric calf-muscle training proceeded as follows: athletes stood on a step, with the front edge of the step touching the soles of the athletes' shoes about one-third of the way from the toes to the heel (so that the heels were basically hovering in mid-air). Body position was upright, legs were straight, and all body weight was supported by the forefeet. The athletes then used their good calf muscle (the one not associated with a hurting achilles) to lift the body upward and plantar flex the ankles, bringing the heels upward while the forefeet remained in contact with the step

    Then, the healthy leg and foot were removed from contact with the step, and as the unhealthy leg remained straight the patient slowly lowered the heel of the unsound leg to below the level of the step, eccentrically loading the calf muscle attached to the throbbing achilles tendon. That constituted one rep!

    Speed of movement (the velocity with which the heel moved downward) was kept slow throughout the overall training period. Three sets of 15 straight-leg reps were conducted per workout, and there were also three sets of 15 reps performed with the unhealthy leg bent at the knee, to activate a deep-calf muscle called the soleus (when the leg is straight, the well-known gastrocnemius is forced to bear most of the load). These straight-leg and bent-leg series of sets, which really didn't take long to carry out, were performed twice a day, seven days a week, for a total of 12 weeks

    The patients experienced calf-muscle soreness during the first few weeks of their exertions, but they stayed with the programme (they did stop any workout in which they felt disabling pain). Initially, the exercises were performed without added weight, but as the athletes grew stronger, they conducted the exercises while wearing backpacks with added weight, starting with just a few pounds and building up to a greater load as strength increased. Once the athletes became really strong, weight machines were used to provide additional resistance

    No concentric activity
    An extremely interesting aspect of this research was that no concentric work was carried out by the calf muscles attached to the afflicted achilles. Concentric contractions are those in which muscles actually shorten while they are contracting, and of course concentric contractions of the calves would be needed to bring the heels back up above the level of the step and plantar flex the ankles prior to another repetition of the eccentric activity (as you know, eccentric contractions are ones in which muscles elongate while they are contracting, which is exactly what was happening to the athletes' 'unhealthy' calf muscles (ie, the calf muscles attached to the ailing achilles) as their heels dropped below the level of the step

    If there was no concentric action by the unhealthy calves, how did the athletes get back into position (with heels above the step) for another eccentric load? Elementary - once the unhealthy calf was eccentrically strained (with heel lowered below the level of the step), the healthy leg was positioned back on the step, and the calf muscles of the healthy leg were used to push the body upward and bring the ankles into plantar flexion again

    So what happened to the hurting achilles tendons? Prior to the eccentric training, the runners' 'unhealthy' calf muscles were consid-erably weaker than their healthy ones - both eccentrically and concentrically. However, after 12 weeks of eccentric training, there was no difference in strength, either eccentrically or concentrically, even though no concentric training had been carried out with the 'bad' calves

    Illustrating the importance of good calf-muscle strength for allaying achilles problems, the eccentrically trained athletes reduced pain while running (which initially had averaged 81 on a scale of 1 to 100, with 100 being the most-intense-possible pain) to near zero after 12 weeks of training. The best news, however, was that all 15 individuals were back to their normal work schedules, training successfully without further achilles problems. As long as they faithfully performed the eccentric-loading exercises a couple of times per week, they were able to keep their achilles free from serious trouble

    The news wasn't nearly so good for the 'control' group of 15 athletes who abstained completely from eccentric training. All 15 had to undergo surgery, and post-surgical recovery was not so pleasant. In contrast to the eccentrically trained athletes, the 15 surgical patients were unable to re-build calf-muscle strength in the afflicted leg - even 24 weeks after surgery (they used traditional physical therapy rather than the eccentric programme). Thus, calf strength in the problem leg remained below calf strength in the normal leg, making future achilles problems on that side of the body more likely

    What calf muscles really do
    Why was eccentric work so effective at thwarting achilles tendon problems? Although we tend to think that the key function of the calf muscles during running is to provide propulsion during the 'toe-off' portion of the gait cycle (such heel-raising action would be concentric in nature), the truth is that the calf muscles are not even active at that time. Their most important role is to control dorsiflexion of the ankle during the stance phase of running, ie, to prevent the ankle from flexing too much while the foot is planted on the ground, and to prevent abnormal pronation (inward rolling of the foot) during the stance phase of the gait cycle

    If you think about it for a moment, you'll realize that such activity is strongly eccentric: once the foot hits the ground, the lower part of the leg comes forward, and the angle between the top of the foot and the shin narrows (producing dorsiflexion of the ankle). This dorsiflexion pulls hard on the achilles tendon and calf muscles (try it in slow motion to see for yourself), elongating them at the exact time the calf muscles are contracting in an attempt to control the collapse of the shin over the top of the foot (that's eccentric!). In addition, the foot rolls inward naturally during the stance phase, twisting and stretching the achilles tendon and its calf muscles, and the calf muscles must contract vigorously to control this inward rolling (eccentric again!)
     

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