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--- In Supertraining@yahoogroups.com, Roy Stewart
<gila_monster97@...> wrote:
>
> Question(s): what would the research say about
> bi-pedals running downhill as compared to level or
> uphill training in regards to injury prevention and
> overall training effect? What speeds would be used to
> increase human performance (overspeed/long slow
> distance (lsd)/%VO2 max)?
****
Each activity has certain benefits and limitations under specific
circumstances – different biochemical, metabolic, neuromuscular and
physiological adaptations will occur. Consideration should be given
to the gradient (angle), recovery times, total volume, intensity,
type of ground, qualification of athlete, speed etc. Use of these
different training methods must be appropriate to the individual and
phases of training. Like a lot of things apparent simplicity at the
outset is often followed by " - actually-this- is-more-complicated-
than-we-first-thought;" the devil is in the detail. Regarding injury prevention it is quite paradoxical as injuries tend to occur in the eccentric action phase, when the muscle develops tension while lengthening. Yet different types of eccentric actions (fast and slow eccentric action velocities) can also treat certain injuries and prevent them. Human performance is a very general term.
Ground reaction forces during downhill and uphill running
Jinger S. Gottschall , and Rodger Kram
Journal of Biomechanics
Volume 38, Issue 3 , March 2005, Pages 445-452
Abstract
We investigated the normal and parallel ground reaction forces
during downhill and uphill running. Our rationale was that these
force data would aid in the understanding of hill running injuries
and energetics. Based on a simple spring-mass model, we hypothesized
that the normal force peaks, both impact and active, would increase
during downhill running and decrease during uphill running. We
anticipated that the parallel braking force peaks would increase
during downhill running and the parallel propulsive force peaks
would increase during uphill running. But, we could not predict the
magnitude of these changes. Five male and five female subjects ran at
3 m/s on a force treadmill mounted on the level and on 3°, 6°, and 9°
wedges. During downhill running, normal impact force peaks and
parallel braking force peaks were larger compared to the level. At
−9°, the normal impact force peaks increased by 54%, and the
parallel
braking force peaks increased by 73%.
During uphill running, normal impact force peaks were smaller and
parallel propulsive force peaks were larger compared to the level. At
+9°, normal impact force peaks were absent, and parallel propulsive
peaks increased by 75%. Neither downhill nor uphill running
affected normal active force peaks. Combined with previous
biomechanics studies, our normal impact force data suggest that
downhill running substantially increases the probability of overuse
running injury. Our parallel force data provide insight into past
energetic studies, which show that the metabolic cost increases
during downhill running at steep angles.
==========================
Hope that makes sense?:)
Jamie Carruthers
Wakefield, UK
>
>
> --- carruthersjam <Carruthersjam@...> wrote:
>
> >
> > > 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
> >
> >
> >
>
March
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