[Supertraining] Re: Eccentric Action and Muscle Soreness

> Considerable research apparently has shown that significant levels
> of post-exercise soreness or DOMS (Delayed Onset Muscle Soreness)
are produced after regimes of eccentric training. For instance,
Friden et al (1983) (Intl J of Sports Med Vol 4 No 3) determined that
a single session of intense eccentric exercise causes pronounced
DOMS which peaks after 24-72 hours after exercise and disappears
several days later. This soreness is accompanied by a reduced
dynamic strength and damage to the microfibrils and connective
tissue elements such as the Z-bands which are a component of the
Series Elastic Component of the muscle complex.
>
> These researchers also examined the effects of longer periods of
> eccentric exercise (3 sessions a week over a total of 8 weeks) and
discovered that post-exercise soreness not only did not occur after 2-
3 weeks, but the ability to perform eccentric work even increased by
375%. At the same time biopsies revealed that Z-band damage had not
taken place, suggesting that adaptation to eccentric exercise had
occurred. This research was corroborated by Schwane & Armstrong
(1983), who found that downhill running in rats produced a superior
training effect to level or uphill training and prevented injury
more effectively than the latter.
>
> Thus, it would seem that eccentric training tends to cause muscle
> soreness to a significant degree predominantly in novice subjects
or those unused to eccentric activity and that adaptation takes
place among more experienced athletes and minimises the occurrence
of soreness after eccentric activity. This would then suggest that
various therapists and coaches may be exaggerating the dangers or
work-reducing effects of eccentric training.
>
> The process of this adaptation to eccentric loading may also be less
> well understood than we currently may imagine, since the competitive
> weightlifter and bodybuilder regularly apply the principle of
progressive overload, i.e. the gradual and periodic increase in
loading. This type of loading is invariably associated with a
heavily or maximally loaded eccentric phase of joint movement, so
that adaptation to a lower level of eccentric stress logically would
seem to be rather irrelevant to adaptation to higher levels of
eccentric loading.
>

*****
Relevant to the above:

Adaptive response in human skeletal muscle subjected to prolonged
eccentric training.

Int J Sports Med. 1983 Aug;4(3):177-83.
• Friden J,
• Seger J,
• Sjostrom M,
• Ekblom B.

The peripheral adaptation process associated with repeating eccentric
training over a longer period of time was studied in m. vastus
lateralis of eleven healthy males aged 24 +/- 4 years. The maximal
dynamic concentric muscle strength was only slightly improved after 8
weeks of training. However, eccentric work capacity was dramatically
increased (375%). A maximal eccentric stint immediately after
fulfilled 8 weeks of training caused a selective glycogen depletion
from the type 28 fibers. An increased number of type 2C fibers was
observed. The ultrastructure analysis showed an essentially well-
preserved fine structure. Volume density of mitochondria was somewhat
higher in all fiber types after training. Z-band widths were not
affected by eccentric training.

It is concluded that skeletal musculature adapts itself in a
functional manner to the extreme tension demands put on them.
Improved coordination and reorganization of the contractile apparatus
of muscle fibers are the determining mechanisms of this adaptation.

---------------------
Myofibrillar damage following intense eccentric exercise in man.

Int J Sports Med. 1983 Aug;4(3):170-6.

• Friden J,
• Sjostrom M,
• Ekblom B.

Muscle soreness that has a delayed onset is a common feature among
both athletes and untrained individuals who engage in unusual
exercises. This study was designed to provide additional
morphological data to assess the relevance and significance of our
previous findings that the sore muscles contain fibers with
disorganized myofibrillar material.

Muscle biopsies were obtained from 12 males (mean age 25 +/- 7
years), who suffered from severe soreness in their thigh muscles 18--
72 h following eccentric bicycle exercise. Their strength performance
were tested in parallel. Knee extensor strength was decreased at all
angular velocities soon after exercise but gradually increased over
the subsequent days although slower at the fastest contractions.
Disturbances of the cross-striated band pattern were constantly
observed. They originated from the myofibrillar Z-band, which showed
marked streaming, broadening and, at places, total disruption. The
disturbances were found in every second to every third fiber up to 3
days after exercise and in one tenth of the fibers 6 days following
the exercise. Type 2 fibers were predominantly affected. Thus, the
eccentric exercise gives rise to muscles soreness and influences, on
mechanical basis and selectively with regard to fiber type, the fine
structure of the contractile apparatus.

======================
Jamie Carruthers
Wakefield, UK

__._,_.___