Literature Review

The Effects of Stretching on Strength Performance

Article· Literature Review (PDF Available)inSports Medicine 37(3):213-24 · February 2007with 12,402 Reads 
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DOI: 10.2165/00007256-200737030-00003 · Source: PubMed
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Abstract
Strength and flexibility are common components of exercise programmes; however, it is not clear how best to include both of these elements in a single training programme. It is common practice among athletes, coaches and recreational exercisers to perform a stretching routine before a strength training session. Stretching exercises are regularly recommended, even in many textbooks, with the claimed purpose of preventing injury and muscle soreness, or even enhancing performance. However, as highlighted in recent review articles, this recommendation lacks scientific evidence. Thus, the purpose of the present review is to determine the acute and chronic effects of stretching on strength performance, together with the underlying mechanisms. Although most studies have found acute decreases in strength following stretching, and that such decreases seem to be more prominent the longer the stretching protocol, the number of exercises and sets, and the duration of each set have, in general, exceeded the ranges normally recommended in the literature. Consequently, the duration of the stimuli were excessively long compared with common practice, thus making evident the need for further studies. In addition, when recommending flexibility exercises, one should consider other underlying issues, such as the safety of the participants, possible increases in injury risks and the unnecessary time expenditure. Many mechanisms underlying stretching exercises still demand investigation so that links between the observed effects, their causes and the consequences may be constructed.
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2007 Adis Data Information BV. All rights reserved.
The Effects of Stretching on
Strength Performance
Ercole C. Rubini,
1,2
Andr
´
e L.L. Costa
2
and Paulo S.C. Gomes
2
1 Universidade Est
´
acio de S
´
a, Rio de Janeiro, Brazil
2 Laboratory Crossbridges and Department of Physical Education from Universidade Gama
Filho, Center for Interdisciplinary Research in Health, Rio de Janeiro, Brazil
Contents
Abstract ....................................................................................213
1. Acute Effects of Stretching on Strength Performance ........................................214
1.1 Effects on Isotonic, Isometric and Isokinetic Strength Tests ................................214
1.2 Effects on Jumping Performance ......................................................215
2. Chronic Effects of Stretching on Strength Performance ......................................215
3. Adaptation Mechanisms..................................................................218
3.1 Neurological Adaptations ............................................................218
3.2 Structural Adaptations ...............................................................220
3.3 Cellular Adaptations .................................................................220
3.4 Hormonal Adaptations ...............................................................221
4. Conclusions .............................................................................221
Strength and flexibility are common components of exercise programmes;
Abstract
however, it is not clear how best to include both of these elements in a single
training programme. It is common practice among athletes, coaches and recrea-
tional exercisers to perform a stretching routine before a strength training session.
Stretching exercises are regularly recommended, even in many textbooks, with
the claimed purpose of preventing injury and muscle soreness, or even enhancing
performance. However, as highlighted in recent review articles, this recommenda-
tion lacks scientific evidence. Thus, the purpose of the present review is to
determine the acute and chronic effects of stretching on strength performance,
together with the underlying mechanisms. Although most studies have found
acute decreases in strength following stretching, and that such decreases seem to
be more prominent the longer the stretching protocol, the number of exercises and
sets, and the duration of each set have, in general, exceeded the ranges normally
recommended in the literature. Consequently, the duration of the stimuli were
excessively long compared with common practice, thus making evident the need
for further studies. In addition, when recommending flexibility exercises, one
should consider other underlying issues, such as the safety of the participants,
possible increases in injury risks and the unnecessary time expenditure. Many
mechanisms underlying stretching exercises still demand investigation so that
214 Rubini et al.
links between the observed effects, their causes and the consequences may be
constructed.
Exercise programmes often include strength and LINE (1966–2006), EMBASE (1974–2006), Coch-
flexibility training. Both components are considered rane Database of Systematic Reviews (1993–2006),
fundamental for those who wish to attain a healthy Lilacs (1982–2006) and SciELO (1997–2006). Ref-
physical fitness level.
[1]
However, the best way to erences listed on recent reviews
[5-9,31-34]
on the topic
include both components in a single training session were also retrieved. The computer search used the
is not yet clear. following keywords individually or combined:
‘flexibility’, ‘stretching’, ‘elasticity’, ‘range of
It is common practice among athletes, coaches
movement’, ‘range of motion’, ‘training’, ‘injury’
and recreational exercisers to perform a stretching
and ‘warm-up’. These keywords were further com-
routine before the main exercise session, such as
bined with ‘resistance exercise’, ‘resistance train-
strength training. In addition, stretching exercises
ing’, ‘strength training’ and/or ‘acute effects’ or
have been recommended in many textbooks for the
‘chronic effects’. Most studies retrieved were in
claimed purpose of preventing injury and muscle
English, although articles in Portuguese and Spanish
soreness, and even enhancing performance. Two
were also considered in this search. All studies
randomized studies
[2,3]
investigating the effect of
related to the acute effects of stretching on strength
stretching before the main exercise session conclud-
performance were considered, regardless of the
ed that this did not decrease injury risks. Regarding
methodological aspects; however, a critical assess-
the reduction of delayed onset muscular soreness
ment of the text was included when needed.
(DOMS), only one study observed reduction in sore-
ness;
[4]
however, this occurred 72 hours after maxi-
1. Acute Effects of Stretching on
mum eccentric knee flexion. Results from this study
Strength Performance
should be interpreted with caution because, not only
did it take a long time for the beneficial effects to be
noticed, but the sample size was also very small (ten
1.1 Effects on Isotonic, Isometric and
females). Recent reviews
[5-9]
have suggested that
Isokinetic Strength Tests
stretching exercises do not protect against injury,
Many authors have studied the acute effect of a
nor do they diminish DOMS or enhance perform-
stretching routine on strength performance, but the
ance.
results are often controversial. Various studies, with
Stretching routines appear to have a negative
total stimuli duration varying from 120 to 3600
acute effect on the subsequent main activity, partic-
seconds, found that stretching exercises preceding
ularly when this is predominantly strength-depen-
the main strength activity significantly decreased
dent.
[10-30]
As stretching exercises are traditionally
performance.
[10-30]
All of these studies used static
recommended before most physical activities, it is
stretching, except for one article that used ballistic
important to determine to what extent a stretching
exercises
[15]
and three that used proprioceptive neu-
routine may influence performance of the main ac-
romuscular facilitation (PNF) stretching.
[21,24,25]
De-
tivity.
creases in strength ranged from 4.5% to 28%, irre-
The present study had two purposes: (i) to review
spective of the testing mode (i.e. isometric, isotonic
the acute and chronic effects of stretching on
or isokinetic). Most studies used lower body exer-
strength performance; and (ii) to review the underly-
cises, except for Evetovich et al.,
[18]
who investigat-
ing mechanisms associated with these adaptations.
ed the biceps brachii. Tests were isotonic (one repe-
Scientific articles were obtained from an exten- tition maximum [RM]), isokinetic (peak torque) and
sive search on several databases, including MED- isometric (peak torque and maximum voluntary
2007 Adis Data Information BV. All rights reserved. Sports Med 2007; 37 (3)
Effects of Stretching on Strength 215
contraction). In contrast to these results, other au- (15 or 30 seconds) did not influence the degree of
force loss following static stretching.
thors
[35-40]
did not observe any detrimental effects of
stretching on strength. The total stimuli duration in
1.2 Effects on Jumping Performance
these studies was shorter, ranging from 30 to 480
seconds. Bandeira et al.
[41]
did not observe decreases
Several studies have investigated the acute effect
in strength performance of ballet dancers when us-
of stretching exercises on vertical jump perform-
ing 15 seconds of static active stretching exercises,
ance. Church et al.
[48]
reported a significant decrease
with a total of 90 seconds stretching. On the other
in performance when this was preceded by PNF
hand, when using 60 seconds for each exercise (360
stretching, but not by static stretching. This confirms
seconds total stimuli), performance of the hip flex-
the findings of Power et al.
[22]
and Knudson et al.,
[49]
ors was decreased, but not that of the hip extensors
who investigated the effects of static stretching and
(table I).
also found no significant decreases in vertical jump
performance. On the other hand, two studies did not
Most studies showed decreases in strength per-
find decreases in vertical jump performance in
formance when preceded by stretching exercises.
trained women either after PNF stretching
[50]
and
However, it should be noted that these studies used
following static or ballistic stretching.
[51]
Other stud-
more than one stretching exercise for the same mus-
ies found decreases in vertical jump performance
cle group and/or the number of sets and the duration
after static stretching,
[52-55]
ranging from
4.5% to
of stretching were greater than the ranges normally
7.3% and
3.2% to
4.4% with and without
recommended in the literature and used in sporting
counter movement, respectively (table II).
activities. It has been recommended that four sets of
Muscular strength is one of the most important
stretching is performed for each muscle group,
[42]
factors in performing the vertical jump. If stretching
with 10–30 seconds duration in each stretched posi-
has the acute effect of reducing performance in
tion.
[42-46]
For individuals >65 years of age, a longer
strength, it would be expected to reduce that of
duration of 60 seconds should be used.
[47]
Therefore,
jumping as well. In practice, this information is
it is possible that the total stretching duration may
highly important for sporting events in which
have been excessively long in the studies showing
strength and jumping performance are fundamental,
decreases in strength performance.
since a decrease in performance may hinder the final
Data from our laboratory
[21,25]
showed 8.9% and
result. It is possible that conflicting results could be
12.3% reductions in hip adductor isometric strength
explained by the different methods used for stretch-
ing or by the absence of information regarding relia-
measured at 45°, and 10.4% and 10.9% at 30° fol-
bility and precision of these methods. Therefore, it is
lowing four 30-second sets of static or PNF (‘con-
clear that this subject deserves further investigation.
tract-relax’ technique) stretching, respectively. De-
In addition, studies investigating the chronic effect
creases in strength after static stretching in knee
of stretching on jump performance are also required.
flexion and extension were 9.9% and 2.3%, and
decreases after PNF were 11.4% and 4.8%, respec-
2. Chronic Effects of Stretching on
tively. These findings concur with the evidence that,
Strength Performance
even with a total stretching time following the litera-
ture recommendations and with only one exercise
Very few studies have looked into the chronic
for each muscle group, a significant decrease in
effects of stretching on strength performance. Wor-
strength performance may still take place. Interest-
rel et al.
[56]
used static and PNF ‘contract-relax’
ingly, the deleterious effect of stretching on strength
methods to train the flexibility of the hamstrings;
performance seems to occur even with experienced
exercises were performed five times a week, for 3
stretchers, as evidenced by Nelson et al.
[23]
Recent-
consecutive weeks, totaling 15 sessions with 20
ly,
[29]
it was shown that the duration of the stimuli minutes per method, per session. Handel et al.
[57]
2007 Adis Data Information BV. All rights reserved. Sports Med 2007; 37 (3)
216 Rubini et al.
2007 Adis Data Information BV. All rights reserved. Sports Med 2007; 37 (3)
Table I. Studies investigating the acute effect of stretching on strength performance
Reference Type of stretching Duration of Muscles stretched Muscles tested Total duration Type of action Results
(sample size) stretching (s)
Kokkonen et al.
[10]
Static 5 exercises Hamstrings, hip Hamstrings, 450 Isot 7.3% flexion
M (n = 15); (passive) [assis./ 3 × 15s adductors, plantar quadriceps 1RM 8.1% extension
F (n = 15) not assis.] 15s rest flexors,
quadriceps
Muir et al.
[35]
Static 1 exercise Plantar flexors Plantar flexors, 120 Isok No change in performance
M (n = 20) (active) 4 × 30s dorsi flexors
10s rest
Avela et al.
[11]
Static 1 exercise Plantar flexors Plantar flexors 3600 Isom 23.2% MVC
M (n = 20) (passive) 1 × 60 min
Fowles et al.
[12]
Static 1 exercise Plantar flexors Plantar flexors 1755 Isom 28% MVC
M (n = 6); (passive) 13 × 135s
F (n = 4)
Nelson et al.
[16]
Static 3 exercises Quadriceps Quadriceps 360 Isok 7.2% 60°/s PT
M (n = 10); (active and 4 × 30s 4.5% 90°/s PT
F (n = 5) passive) 20s rest
Nelson et al.
[14]
Static 2 exercises Quadriceps Quadriceps 240 Isom 7% PT, at angle of 162°
M (n = 25); (passive) 4 × 30s
F (n = 30) 20s rest
Behm et al.
[13]
Static 4 exercises Quadriceps Quadriceps 900 Isom 12.2% MVC
M (n = 12) (passive) 5 × 45s
15s rest
Nelson and Ballistic 5 exercises Hamstrings, thigh Hamstrings, 450 Isot 7.5% flexion
Kokkonen
[15]
adductors, plantar quadriceps 1RM 5.6% extension
M (n = 11); flexors,
F (n = 11) quadriceps
Tricoli and Static 6 exercises Quadriceps, Quadriceps, 540 Isot 13.8% maximum strength
Paulo
[17]
(active) 3 × 30s hamstrings hamstrings 1RM
M (n = 11) 30s rest
Garrison et al.
[37]
Static NA Quadriceps Quadriceps 480 Isok No change in performance
(n = 29)
Mello and Static 2 exercises Hamstrings, Hamstrings, 30 Isok No change in
Gomes
[36]
(passive) 2 × 15, 30 and quadriceps quadriceps 60 performance
M (n = 5); 60s 120
F (n = 3) 10s rest
Evetovich et al.
[18]
Static 3 exercises Biceps brachii Biceps brachii 360 Isok 30°/s PT
M (n = 10); (2 active; 1 4 × 30s 270°/s PT
F (n = 8) passive) 15s rest
Bandeira et al.
[41]
Static 6 exercises Hip flexors, hip Hip flexors, hip 90 or Isok Flexors 60°/s
F (n = 10) (active) 1 × 15s and 60s extensors extensors 360
Continued next pag
e
Effects of Stretching on Strength 217
2007 Adis Data Information BV. All rights reserved. Sports Med 2007; 37 (3)
Table I. Contd
Reference Type of stretching Duration of Muscles stretched Muscles tested Total duration Type of action Results
(sample size) stretching (s)
Avela et al.
[19]
Static 2 exercises Plantar flexors Plantar flexors 360 Isom 13.8% MVC (1st measure)
M (n = 8) (passive) 60 min 13.2% MVC (2nd measure)
2 weeks between
exercises
Cramer et al.
[20]
Static 4 exercises Quadriceps Quadriceps 480 Isok 3.3% 60°/s PT
F (n = 14) (1 active; 4 × 30s 2.6% 240°/s PT
3 passive) 20s rest
Rubini et al.
[21]
Static 1 exercise Hip adductors Hip adductors 120 Isom 45°: 8.9% and 12.3%
M (n = 18) PNF 4 × 30s or 30°: 10.4% and 10.9%
(passive) 4 × (3 × 10s) (static and PNF, respectively)
Cramer et al.
[38]
Static 4 exercises Quadriceps Quadriceps NA Isok No change in performance
M (n = 15) (1 active;
3 passive)
Behm et al.
[39]
Static 3 exercises Quadriceps Quadriceps 405 Isom No change in performance
M (n = 16) (passive) 3 × 45s hamstrings,
15s rest plantar flexors
Power et al.
[22]
Static 6 exercises Quadriceps Quadriceps, 810 Isom 9.5% MVC quadriceps and no
M (n = 12) 3 × 45s hamstrings, plantar flexors (270 for each change in plantar flexors
15s rest plantar flexors muscle group)
Mello and Static 6 exercises Quadriceps, Quadriceps, 3600 Isok 9.9% and 2.3%
Gomes
[25]
PNF 30s or (3 × 10s) hamstrings hamstrings 11.4% and 4.8% (static and
F (n = 17) (passive) PNF; flexion and extension,
respectively)
Marek et al.
[24]
Static 4 exercises Quadriceps Quadriceps 120 (static) Isok 2.8%
M (n = 9); PNF 5 × 30s 120 (PNF) (static and PNF)
F (n = 10) (passive) 30s rest
Nelson et al.
[23]
Static 5 exercises Quadriceps, Quadriceps, 1200 Isot 3.2% extension
M (n = 13); (passive) [assis./ 3 × 15s hamstrings hamstrings 1RM 5.5% flexion
F (n = 18) not assis.] 15s rest
Cramer et al.
[26]
Static 4 exercises Quadriceps Quadriceps 966 Isok 60°/s and 240°/s PT (dominant)
M (n = 7); (passive) 4 × 30s (dominant) (dominant/not 60°/s PT (not dominant)
F (n = 14) 20s rest dominant)
Derek et al.
[27]
Static 1 exercise Plantar flexor Plantar flexor 600 Isom 7% MVC
M (n = 15) (passive) 5 × 120s
Behm et al.
[28]
Static 3 exercises Quadriceps, Quadriceps 270 Isom 6.5% MVC
(Pre) (passive) 3 × 30s hamstrings,
M (n = 9); 30s rest plantar flexors
F (n = 9)
Continued next pag
e
218 Rubini et al.
used the PNF ‘contract-relax’ method to train the
knee extensor and flexor muscles; exercises were
performed three times a week for 8 consecutive
weeks, with a total of 86 minutes 40 seconds in each
session. The study by Worrel et al.
[56]
showed no
significant gains in flexibility, but 8.5% and 13.5%
increases in eccentric peak torque measured at 60°/s
and 120°/s, respectively, and 11.2% increase in con-
centric peak torque at 120°/s. Significant increases
in flexibility (up to 6.3%), in knee flexor and exten-
sor muscle eccentric peak torque (18.2% and 23.0%,
respectively), knee flexor concentric peak torque
(9.4%) and knee flexor isometric peak torque
(11.3%) were found by Handel et al.
[57]
Despite the need for more studies, the enhance-
ment of strength following flexibility training may
be attributed to hypertrophy of the stretched mus-
cles. Muscle hypertrophy has been observed in ani-
mals that underwent stretching protocols lasting 24
hours per day, for 3–30 days.
[58-60]
Although these
studies were conducted with animals, researchers
used stretching methods and duration that differed
greatly from those recommended for humans for
gains in flexibility, thus limiting applicability of
these results. In the case of humans, gains in strength
seem to occur after 3 weeks of flexibility training,
without any specific training for strength develop-
ment.
[56,57]
Therefore, evidence suggests that, al-
though stretching exercises may have a negative
acute effect on strength, this may not be the case
after chronic stretching.
3. Adaptation Mechanisms
3.1 Neurological Adaptations
Although evidence is still lacking, some authors
have tried to explain the possible neural mechanisms
underlying the acute effects of stretching exercises
and their effects on muscle strength performance.
The literature is rather inconclusive and some of the
findings do not relate to one other.
Rosenbaum and Henning
[61]
observed a signifi-
cant 5% decrease in isometric peak torque following
3 minutes of static stretching of the triceps surae,
which was accompanied by an increase in muscular
2007 Adis Data Information BV. All rights reserved. Sports Med 2007; 37 (3)
Table I. Contd
Reference Type of stretching Duration of Muscles stretched Muscles tested Total duration Type of action Results
(sample size) stretching (s)
Behm et al.
[28]
Static 3 exercises Quadriceps, Quadriceps 270 Isom 8.2% MVC
(Post) (passive) 3 × 30s hamstrings,
M (n = 12) 30s rest plantar flexors
Brandenburg
[29]
Static 2 exercises Hamstrings Hamstrings 90 or Isom 15s
M (n = 10); (assist./not 3 × 15s or 30s 180 Conc 30s
F (n = 6) assist.) 30s rest Exce NS difference between type of
actions
Egan et al.
[40]
Static 4 exercises Quadriceps Quadriceps 480 Isok NS 60°/s
F (n = 11) 4 × 30s NS 300°/s
20s rest 5 min after stretching
Yamaguchi et Static 6 exercises Quadriceps Quadriceps 720 Isom 5% MVC
al.
[30]
(3 assist.; 4 × 30s 30% MVC
M (n = 20) 3 not assist.) 20s rest 60% MVC
assis. = assisted; conc = concentric; exce = excentric; F = females; Isok = isokinetic; Isom = isometric; Isot = isotonic; M = males; MVC = maximum voluntary contraction; NA =
not available; NS = statistically not significant; PNF = proprioceptive neuromuscular facilitation; Post = after a 4-week training programme; Pre = before training programme; PT =
peak torque; RM = repetition maximum; indicates decrease.
Effects of Stretching on Strength 219
Table II. Studies investigating the acute effect of stretching on jumping performance
Reference Method Sets and exercises Muscles stretched Stimuli Test Results
(sample size) duration (s)
Church et al.
[48]
Static 3 sets Quadriceps, hamstrings NA VJ PNF
F (n = 40) PNF NS static
Cornwell et al.
[52]
Static 1 set Hip extensors, knee 90 VJ 4.4% (VJ)
M (n = 10) (passive) 3 exercises extensors 4.3% (VJCM)
Knudson et al.
[49]
Static 3 sets Quadriceps, hamstrings, 45 VJ NS (VJ)
M (n = 10); F (n = 10) 3 exercises plantar flexors
Cornwell et al.
[53]
Static 3 sets Triceps surae 180 VJ 7.3% (VJCM)
M (n = 10) (passive) 2 exercises NS (VJ)
Serzed
ˆ
elo Corr
ˆ
ea et al.
[50]
PNF 3 exercises Quadriceps, hamstrings, 240 VJ NS (VJ)
F (n = 10) (CR) calf, gluteus LJ 10.7% (LJ)
Young and Behm
[54]
Static 4 exercises Quadriceps, plantar 120 VJ 3.2% (VJ)
M (n = 13); F (n = 3) flexors
Power et al.
[22]
Static 2 sets Quadriceps, hamstrings, 270 VJ NS (VJ)
M (n = 12) 3 exercises plantar flexors
Unick et al.
[51]
Static 3 sets Quadriceps, hamstrings, 180 VJ NS (VJ)
F (n = 16) Ballistic 4 exercises plantar flexors Statistic/Ballistic
Wallmann et al.
[55]
Static 3 sets Gastrocnemius 90 VJ 5.6% (VJ)
M (n = 8); F (n = 6) (passive)
CR = contract/relax; F = females; LJ = long jump; M = males; NA = not available; NS = statistically not significant; PNF = proprioceptive
neuromuscular facilitation; VJ = vertical jump; VJCM = vertical jump with counter movement; indicates increase; indicates decrease.
compliance. Muscle offers less resistance to passive afferents and producing a smaller electromy-
ographic amplitude.
stretching and increases its capability of distending
when muscular compliance increases. This phenom-
In addition to these mechanisms, other neural
enon is know as ‘stress relaxation’, which is a loss in
systems may be involved, such as activation of
nociceptors and inhibition generated by Golgi ten-
tension occurring when the muscle is stretched with
don organs, which contribute to a decrease in excita-
a constant length and which occurs irrespective of
bility of the α motoneuron.
[13]
An increased inhibi-
observed electromyographic alterations, as suggest-
tory drive of the α motoneuron pool generated by
ed by McHugh et al.
[62]
Thus, muscle compliance
types III and IV joint receptors after stretching exer-
resulting from stretching is suggested as one of the
cise was also suggested by Avela et al.
[63]
mechanisms responsible for the decrease in muscu-
Halbertsma and G
¨
oeken,
[64]
investigated the ef-
lar performance.
fects of 10 minutes of static stretching on subjects
In another study, Fowles et al.
[12]
found that there
with shortened hamstring muscles. The authors con-
was a decrease in motor unit activation and in elec-
cluded that the effect of such exercises would not be
tromyographic activity immediately following pas-
due to alterations in muscle elasticity, but to a
sive stretching of the plantar flexors. In addition,
greater tolerance to stretching. The same conclu-
there was a 28% decrease in maximum voluntary
sions were reported by Magnusson et al.
[65]
in a
contraction, which was still depressed by 9% 1 hour
study of static stretching of the hamstrings over 3
after stretching cessation.
weeks and by Halbertsma et al.
[66]
after a 10-minute
In the study by Avela et al.,
[11]
maximum volun-
session of 30 seconds of static stretching of the
tary activation was decreased by 23.2% immediately hamstrings with rest intervals of 30 seconds.
following 1 hour of repeated passive stretching of
Therefore, there seems to be a reduction in sensi-
the triceps surae. The authors observed a reduction
bility of the muscle, tendon, joint receptors and
in sensitivity to repeated stretches of the muscle
nociceptors, which are fundamental mechanisms for
spindles, reducing the activity of the large-diameter the protection of structures involved in motion. In
2007 Adis Data Information BV. All rights reserved. Sports Med 2007; 37 (3)
220 Rubini et al.
addition to these alterations, there is a period where lasting for 45 seconds, with 15 seconds of rest
neuromotor responses are delayed immediately fol- between exercises. The authors concluded from the
lowing stretching exercises. These acute neural al- latter two studies that training decreased the viscosi-
terations may be related to the observed decrease in ty of the tendinous structures, but did not alter
strength and may predispose to or increase the risks elasticity.
of injury, although this requires further investiga-
Still trying to understand muscle elasticity,
tion.
Edman and Tsuchiya
[72]
concluded that during
stretching exercises the most affected elastic struc-
3.2 Structural Adaptations
ture was the titin, and that compliance properties of
tendons and all the other elastic structures were less
One of the hypotheses suggested for the reduc-
than for this protein. This concurs with other studies
tion in strength performance following successive
that have shown titin to be the main structure re-
stretching is the alteration of viscoelastic properties
sponsible for muscular elasticity.
[73,74]
Further inves-
of the muscle, which, in turn, may alter the length-
tigating this question, Avela et al.
[63]
hypothesised
tension relationship. However, there seems to be no
that the increase in compliance caused by stretching
consensus on the subject.
would be responsible for the decrease in the re-
Toft et al.
[67]
investigated viscoelastic and plas-
sponse caused by muscle spindles and, subsequent-
ticity properties of the plantar flexor muscles. They
ly, a lower activity of α motoneurons. Rubini and
concluded that these muscles experienced no modi-
Gomes
[75]
provide a review of the role of titin in
fication when measured 90 minutes after a passive
muscular elasticity.
stretching programme, nor at 24 hours after 3 weeks
Therefore, stretching exercises seem to acutely
of training twice a day. On the other hand, Taylor et
produce a decrease in viscosity of the tendinous
al.
[42]
observed a capacity to alter the length of the
structures, allowing muscle fibres to slide with less
musculo-tendinous unit of rabbits following stretch-
resistance to movement. At the same time, stretch-
ing, thus decreasing passive tension. Toft et al.
[68]
ing exercises generate an increase in muscle compli-
found 36% decreases in passive tension of the plan-
ance that may limit more crossbridge coupling, thus
tar flexors after 3 weeks of ‘contract-relax’ flexibili-
decreasing the capacity of the muscle to produce
ty training, twice a day. Furthermore, these authors
force.
found no significant correlation between the initial
Chronic studies with stimuli of longer duration
flexibility level of the subjects and the effect of
may help to improve understanding of the structural
stretching on passive tension, which was equivalent
adaptations and their effects on strength perform-
for all levels.
ance resulting from stretching exercises.
In order to understand the viscoelastic alterations
resulting from stretching, the same group of authors,
3.3 Cellular Adaptations
in three different studies, used ultrasound to observe
the medial gastrocnemius tendon and aponeurosis De Deyne,
[76]
in an attempt to explain the perma-
before and after stretching. Kubo et al.
[69]
concluded nent increase in range of motion resulting from
that 10 minutes of static stretching decreased the flexibility training, suggested a chronic adaptation
viscosity of the tendinous structures and increased through cellular mechanisms, such as new serial
their elasticity. In a chronic study,
[70]
the same group sarcomere addition. Myofibrilogenesis has been ob-
combined resistance exercises with static stretching; served in animals
[77-80]
and occurs, basically, in the
exercise were performed for 45 seconds with insertion of muscles exposed to casting, with the
15-second intervals, two sessions a day, 7 days a muscle immobilised in a stretched position for 24
week for 8 weeks. In a third study,
[71]
the subjects hours a day, over several days. However, these
performed static stretching in 20 consecutive days, models are very different from the methods normal-
with two sessions a day of five stretching exercises, ly used in flexibility programmes for humans.
2007 Adis Data Information BV. All rights reserved. Sports Med 2007; 37 (3)
Effects of Stretching on Strength 221
Significant increases in protein synthesis were rapid increase in the number of ribosomal RNA,
found in studies with mice
[81]
that were exposed to indicating that hypertrophy of the muscle fibers
casting immobilization in a stretched position for 7 occur during translation.
[84,86]
These findings
days. The author suggested that stretching was the showed that stretching is capable of promoting in-
stimulating factor for protein synthesis. creases in muscle strength or hypertrophy. Never-
theless, the experimental conditions of the studies
Whether the addition of new sarcomeres has a
discussed in section 3.4 are very different from the
beneficial or detrimental effect on strength is still
conditions normally recommended and applied to
not known. This is a question that requires further
humans.
investigation, despite the difficulty in conducting
long-term studies. Studies that observed the occur-
rence of myofibrilogenesis in animals did not inves-
4. Conclusions
tigate the effects on strength, and the very few
Flexibility and strength are fitness components
chronic studies that investigated the effects of
that are fundamental in many sports modalities and
stretching on strength did not investigate the occur-
even for common daily motor tasks. Training for
rence of myofibrilogenesis.
flexibility and strength is widely recommended for
those who wish to attain good fitness levels and a
3.4 Hormonal Adaptations
better quality of life. Many activities rely heavily on
strength, but strength performance may be dimin-
During the last two decades, several studies have
ished by a preceding stretching routine; therefore, it
been carried out with the aim of observing the
is important to understand this phenomenon when
hormonal changes due to stretching. Some studies
prescribing physical exercise programmes. There
were conducted with animals being immobilised in a
appears to be substantial evidence suggesting a de-
stretched position for various days by casting. Gold-
crease in strength following stretching. Studies used
spink et al.
[58]
observed that stretching increased
different stretching techniques, duration and
insulin-like growth factor (IGF)-1 messenger RNA
targeted different muscle groups, and were tested
(mRNA) levels in mice. Yang et al.,
[82]
analysing
with isotonic, isometric or isokinetic devices. How-
possible hormonal alterations in rabbits, observed
ever, the number of exercises, duration of each
that stretching generated an IGF-1 isoform (IGF-1
exercise and number of sets (i.e. the total duration of
Eb), corresponding to the human IGF-1 Ec isoform,
stretching) was much longer than the ranges normal-
which is related to muscular growth. In another
ly used in practice and what is recommended in the
study, Yang et al.
[60]
observed increases in IGF-1
literature. This makes evident the need for further
mRNA levels, which correlated with increases in
studies with designs that do not threaten their exter-
muscle mass in rabbits. IGF-1 Ec, also known as
nal validity. Training studies should also be con-
mechano growth factor (MGF), is an IGF splice
ducted in order to assess whether the decreases in
variant that has autocrine and paracrine functions
strength observed during the training session will
capable of stimulating protein synthesis and muscle
have long-term consequences (i.e. suboptimal gains
hypertrophy.
[83]
Its secretion is stimulated in re-
in strength when compared with training without
sponse to mechanical stimuli such as force genera-
prior stretching).
tion and stretching, with stretching being the main
mechanical stimulus.
[83,84]
MGF locally controls tis- Furthermore, the safety of the participants should
sue repair, maintenance and remodeling.
[83,85]
The be taken into consideration in the recommendation
discovery of MGF finally linked the mechanical of stretching exercises. When the possible effects of
stimulus and genetic expression, demonstrating that these exercises are analysed, it seems that many of
cellular phenotypes are not determined only in the the mechanisms responsible for maintaining the
genome.
[84,86]
A particular function of MGF is to myo-osteo-articular integrity, such as muscle, ten-
activate satellite muscle cells.
[83,85]
MGF generates a don and joint receptors, are inhibited following
2007 Adis Data Information BV. All rights reserved. Sports Med 2007; 37 (3)
222 Rubini et al.
10. Kokkonen J, Nelson AG, Cornwell A. Acute muscle stretching
stretching. Tolerance to pain also seems to be in-
inhibits maximal strength performance. Res Q Exerc Sport
creased, allowing range of motion to be greater and
1998; 69 (4): 411-5
11. Avela J, Kyr
¨
ol
¨
ainen H, Komi PV. Altered reflex sensitivity after
closer to the maximal limit of the stretched struc-
repeated and prolonged passive muscle stretching. J Appl
tures, and consequently, closer to injury risk. The
Physiol 1999; 86 (4): 1283-91
hypothesis that flexibility exercises preceding other
12. Fowles JR, Sale DG, Macdougall JD. Reduced strength after
passive stretch of the human plantarflexors. J Appl Physiol
physical activities may lead to greater injury risks
2000; 89: 1179-88
should be considered and investigated in future stud-
13. Behm DG, Button DC, Butt JC. Factors affecting force loss with
ies.
prolonged stretching. Can J Appl Physiol 2001; 26: 262-72
Many mechanisms underlying stretching exer-
14. Nelson AG, Allen JD, Cornwell A, et al. Inhibition of maximal
voluntary isometric torque production by acute stretching is
cises still demand investigation so that links be-
joint-angle specific. Res Q Exerc Sport 2001; 72 (1): 68-70
tween the observed effects, their causes and conse-
15. Nelson AG, Kokkonen J. Acute ballistic muscle stretching
quences may be constructed.
inhibits maximal strength performance. Res Q Exerc Sport
2001; 72 (4): 415-9
16. Nelson AG, Guillory IK, Cornwell A, et al. Inhibition of maxi-
Acknowledgements
mal voluntary isokinetic torque production following stretch-
ing is velocity-specific. J Strength Cond Res 2001; 15: 241-6
17. Tricoli V, Paulo AP. Efeito agudo dos exerc
´
icios de alonga-
We would like to thank the Conselho Nacional de
mento sobre o desempenho de for¸ca m
´
axima. Atividade F
´
isica
Desenvolvimento Cient
´
ifico e Tecnol
´
ogico (CNPQ), Minis-
e Sa
´
ude 2002; 7 (1): 6-12
try of Education, Brazil, for their financial support to Ercole
18. Evetovich TK, Nauman NJ, Conley DS, et al. Effect of static
C Rubini. The authors would also like to thank Dr Marta Inez
stretching of the biceps brachii on torque, electromyography,
Rodrigues Pereira for the preparation of the English version
and mechanomyography during concentric isokinetic muscle
of the manuscript and Dr Ana Maria Miragaya for reviewing
actions. J Strength Cond Res 2003; 17 (3): 484-8
the English version. The authors have no conflicts of interest
19. Avela J, Finni T, Liikavainio T, et al. Neural and mechanical
directly relevant to the content of this review.
responses of the triceps surae muscle group after one hour
repeated fast passive stretches. J Appl Physiol 2004; 96:
2325-32
20. Cramer JT, Housh TJ, Johnson GO, et al. Acute effects of static
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E-mail: crossbridges@ugf.br
2007 Adis Data Information BV. All rights reserved. Sports Med 2007; 37 (3)
  • ... Note that the researchers found no study directly focusing on this issue, so these results are not comparable with others in the field. According to Robinie et al, stretching has a negative effect on power, even when its duration is limited [23]. Ogura et al stated that a 30 second static stretch did not lead to a subsequent decline in isometric strength of the hamstring muscle, but 60 seconds of stretching led to a significant reduction [24]. ...
    Article
    Full-text available
    Background: The aim of this study was to investigate the acute effects of static stretch alone and in combination with plyometric exercises on some functional indices in athletes with and without hamstring tightness. Methods: For this controlled laboratory study, 20 female athletes with hamstring tightness and 15 female athletes with normal hamstring participated voluntarily in static stretching exercises or stretching in combination with plyometric exercises in two consecutive days after warm up, with a random stretching order. The maximum voluntary hamstring isometric strength, maximal vertical jump, and Y balance test were also measured. Results: The results indicated that both static stretching and stretching in combination with plyometric exercises may affect balance more adversely in athletes with hamstring tightness. Both types of stretching programs may also cause adverse effects on balance, muscle strength, and maximal vertical jump (P<0.05). Conclusion: According to the results, the level of balance of individuals with hamstring tightness may be affected more adversely through static stretching exercises. Thus, we suggest that the static stretch should not be prescribed for athletes with hamstring tightness at the warm up of training sessions.
  • ... First phase was a 10-minute 143 general warm-up with light stationary cycling at a self-selected cadence. Second phase consisted 144 of dynamic body-weight movements (eight minutes) and light stretching exercises (six stretching 145 exercises performed in two series of ten seconds each, with a total 2 min of static stretching for 146 the main muscle groups involved in test exercises (40). Last five minutes of the preparation 147 were dedicated for proper Biodex chair height and attachments alignment. ...
    Preprint
    Full-text available
    Background: The purpose of this study was to investigate the acute effects of commercially available pre-workout supplement Knockout 2.0 ® on anaerobic performance in resistance trained men. Methods: Twenty-three men underwent three testing sessions administrated in a randomized and double-blind fashion separated by a seven-day break. The participants performed three exercise tests: isokinetic strength test, maximal strength test and Wingate test. Statistical analysis was conducted in R environment. Linear mixed models were estimated via R package lme4. Results: The mean knee peak torque was significantly greater in supplemented group for right and left knee flexors (placebo: 103.17 ± 37.61 Nm, and supplemented group: 131.84 ± 29.31 Nm where p=0.001, and placebo: 103.72 ± 39.35, and supplemented group: 129.38 ± 28.44, where p=0.001; respectively) as well as for right and left knee extensors (placebo: 202.65 ± 58.64 Nm, and supplemented group: 237.22 ± 54.75 Nm where p=0.001, and placebo: 203.27 ± 63.2 Nm versus supplemented group: 229.84 ± 50.8 Nm where p=0.002; respectively).The significant difference was observed in mean anaerobic power between supplemented and placebo group for right and left knee flexors (p=0.002 and p=0.005, respectively) as well as for right and left knee extensors (p=0.001 and p=0.002; respectively).There was also observed that the time to peak torque was significantly greater in supplemented group for right and left knee flexors (p=0.002 for both legs). The significant difference was also observed in mean power between supplemented and placebo group during Wingate test (placebo: 8.49 ± 0.57 W/kg, and supplemented group: 8.66 ± 0.55 W/kg where p=0.038). Moreover the mean 3-RM strength test was significantly greater in supplemented group with p=0.001. Conclusions: The results of the study indicate that Knockout 2.0® significantly improves upper and lower body strength and power output in resistance trained men.
  • ... In addition, another important factor that justifies the high number of players with muscle tightness is the lack of a stretching program as revealed by the questionnaires. The application of stretching will facilitate improved muscle development, whilst avoiding the negative effects (muscle tightness and asymmetry) caused by regular practice of IH [28,85,86]. ...
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    During puberty, the growth of the bones is faster than that of the muscles, which may result in muscular tightness. Muscular tightness and asymmetry have been associated with an increase in injury incidence. The assessment of a joint range of motion (ROM) could help to identify athletes classified as high injury risk. The objectives of the present study were to describe the lower-extremity flexibility profile (LEFP) of youth competitive inline hockey players using the ROM-SPORT battery (I) and to identify muscular tightness and asymmetry (II). Seventy-four young players were examined for maximum passive ankle, knee, and hip ROMs. Muscle asymmetry or tightness was classified according to cutoff scores previously described. The LEFP of the 74 players was 10.8º for hip extension, 26º for hip adduction, 33.6º for ankle dorsiflexion, 38.6º for ankle dorsiflexion with knee flexed, 36.7º for hip abduction, 46º for hip internal rotation, 60.6º for hip external rotation, 65.1º for hip abduction with the hip flexed, 66.3º for hip flexion with the knee extended, 119.7º for knee flexion, and 133.7º for hip flexion. The individual analysis of the flexibility values identified tightness in all players for one or more movement, except for hip abduction. A low prevalence of asymmetries was observed (range: 5.4% to 17.6% of players) depending on the ROM.
  • ... Conversely, the acute effects depressing performance seem to be well established in the literature (Avela, Kyrolainen, & Komi, 1999;Haddad et al., 2013;McHugh & Cosgrave, 2010;Nelson, Driscoll, Landin, Young, & Schexnayder, 2005;Rubini, Costa, & Gomes, 2007;Sayers, Farley, Fuller, Jubenville, & Caputo, 2008;Simic, Sarabon, & Markovic, 2012). Likely, such effects are neurally mediated, as they may affect both the stretched and the non-stretch muscles (Masugi, Obata, Inoue, Kawashima, & Nakazawa, 2017). ...
    Article
    Flexibility is a measurable physical capacity considered as a key component of physical fitness. Poor flexibility is usually attributed to excessive tension exerted by the antagonist muscles of the movement and, supported by weak scientific evidence, passive stretching is considered as the most effective intervention in the promotion of the muscle extensibility, in attempting to improve mobility. The proposal of this paper is a review of the effects of static stretching in human movement and a presentation of strength training as a more robust alternative based on scientific evidence. First, we try to define which factors influence the ability of the human body to move into their functional safety range of motion. Second, we present a critical scientific literature review of the effects of static stretching in the promotion of range of motion, injury prevention, and sports performance. Third, we propose alternatives to static stretching such as proprioceptive neuromuscular facilitation, dynamic stretching, and especially strength/resistance training, in the promotion of a better range of motion. Finally, we conclude that perhaps problems of flexibility/mobility should not be addressed with static processes, but with movement.
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    Direct muscular attachment from lumbar vertebrae to the caudal vertebrae of the tail suggests that caudal traction, also described as tail-pull, may affect lumbar vertebral segments and/or associated soft tissues in horses. Traction is a commonly used human manual therapy technique employed for pain relief and anecdotally observed to relieve pain in horses. However, research is lacking validating the efficacy of manual caudal traction on the horse. The objective of this study was to determine if caudal traction has an effect on mechanical nociceptive thresholds (MNT’s) in a group of horses with clinical signs of back pain. Pressure algometry was used to measure MNT’s of five bilateral anatomical sites in the epaxial and pelvic musculature of 11 horses referred to physiotherapy due to clinical signs of back pain. Measurements were recorded both pre and immediately post traction. A significant difference (P ≤0.05) was identified between mean pre and post caudal traction algometry measurements in all described sites. The percentage of MNT increase was highest in the thoracic region (83%) compared to the lumbar (50%) and the pelvic (52.4%) regions. These results support an effect of caudal traction in increasing MNTs in the thoracolumbar and pelvic regions in horses. Further research to determine the clinical effect of this technique is warranted.
  • Article
    BACKGROUND The purpose of this study is to compare the effects of stretching methods on flexibility, muscle activation, and pressure pain threshold in ballet dancers, and to suggest an effective stretching method. METHODS Thirty-three ballet dancers were randomized to the static stretching group (n=11), muscle energy technique stretching group (n=11), and vibration-assisted stretching group (n=11). The angle of hip joint extension in arabesque, activation of the rectus femoris in devéloppé, and pressure pain threshold on the rectus femoris in the sitting position were measured to compare the effects of the different stretching methods. Paired t-test was used to compare the pre and post-intervention findings within each group and one-way analysis of variance to compare the difference in the amount of changes among the groups. RESULTS The hip joint extension angles increased in all stretching methods (p<0.05); however, vibration-assisted stretching and muscle energy technique stretching were more effective than static stretching (p<0.05). The activation of the rectus femoris decreased in all groups (p<0.05); however the muscle energy technique stretching group and vibration-assisted stretching group showed a significant decrease in muscle activation compared with the static stretching group (p<0.05). The pressure pain threshold significantly improved only in the static stretching group (p<0.05); and vibration-assisted stretching group (p<0.05). CONCLUSIONS Compared with static stretching and muscle energy technique stretching, vibration-assisted stretching is a beneficial method for improving flexibility, muscle activation, and pressure pain threshold in ballet dancers.
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    Background: Previous research has demonstrated a reduction in peak power via isokinetic dynamometry and power testing. The purpose of this study was to determine the effects of static stretching (SS) on the Wingate test (WAnT). Methods: Thirteen recreationally active males (mean age: 22.5±1.9 years, height: 172.5±8.4 cm, body mass: 83.4±24.6 kg) were tested for peak (PP), average (AP), and minimum (MP) power output using the WAnT. Two WAnT trials were completed by each subject on a Monark 894-E ergometer that was interfaced with a desktop computer. Participants completed a 5-minute warm-up on the cycle ergometer and then performed the pre-WAnT. Upon completion, the stretching protocol four static stretches were performed: one was participant self-administered and the remaining three by the investigator. Each stretch was held for 30 seconds and was repeated 4 times on each leg and repeated after 4 minutes of rest. Results: Significant differences (P<0.05) were found for PP only for the pre- versus post-WAnT (802.6±207.6 vs. 768.8±199.7 W). Conclusions: Static stretching before performance of the WAnT demonstrated a significant decrease in peak power output. Based upon these results, it appears that SS decreases peak power output when performing an anaerobic capacity test on a cycle ergometer.
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Literature Review
  • Article
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    Previous research has shown that passive muscle stretching can diminish the peak force output of subsequent maximal isometric and concentric contractions. The purpose of the present study was twofold: 1. to establish if the deleterious effect of stretching on performance also exists for a skill that relies on the rate of force production for success rather than peak force generation and 2. to determine if a similar effect exists for a movement that employs a stretch-shortening action. Ten participants performed two types of maximal vertical jump with and without prior stretching of the hip and knee extensors. Both static jumps (SJ) and countermovement jumps (CMJ) were executed from a force platform. Jump height was calculated from the velocity at takeoff determined from the force/time data. Stretching induced a significant (p<0.05) decrease in jump height for both the SJ (4.4 ± 1.3%) and CMJ (4.3 ± 1.3%). Thus, it appears that pre-performance stretching exercises might negatively impact skills that demand a high power output in addition to those that rely simply on maximizing peak force. Furthermore, it is possible that this detrimental effect is comparable for skills that take advantage of the stretch-shortening phenomenon and those that do not.
  • Article
    It is generally accepted that increasing the flexibility of a muscle-tendon unit promotes better performances and decreases the number of injuries. Stretching exercises are regularly included in warm-up and cooling-down exercises; however, contradictory findings have been reported in the literature. Several authors have suggested that stretching has a beneficial effect on injury prevention. In contrast, clinical evidence suggesting that stretching before exercise does not prevent injuries has also been reported. Apparently, no scientifically based prescription for stretching exercises exists and no conclusive statements can be made about the relationship of stretching and athletic injuries. Stretching recommendations are clouded by misconceptions and conflicting research reports. We believe that part of these contradictions can be explained by considering the type of sports activity in which an individual is participating. Sports involving bouncing and jumping activities with a high intensity of stretch-shortening cycles (SSCs) [e.g. soccer and football] require a muscle-tendon unit that is compliant enough to store and release the high amount of elastic energy that benefits performance in such sports. If the participants of these sports have an insufficient compliant muscle-tendon unit, the demands in energy absorption and release may rapidly exceed the capacity of the muscle-tendon unit. This may lead to an increased risk for injury of this structure. Consequently, the rationale for injury prevention in these sports is to increase the compliance of the muscle-tendon unit. Recent studies have shown that stretching programmes can significantly influence the viscosity of the tendon and make it significantly more compliant, and when a sport demands SSCs of high intensity, stretching may be important for injury prevention. This conjecture is in agreement with the available scientific clinical evidence from these types of sports activities. In contrast, when the type of sports activity contains low-intensity, or limited SSCs (e.g. jogging, cycling and swimming) there is no need for a very compliant muscle-tendon unit since most of its power generation is a consequence of active (contractile) muscle work that needs to be directly transferred (by the tendon) to the articular system to generate motion. Therefore, stretching (and thus making the tendon more compliant) may not be advantageous. This conjecture is supported by the literature, where strong evidence exists that stretching has no beneficial effect on injury prevention in these sports. If this point of view is used when examining research findings concerning stretching and injuries, the reasons for the contrasting findings in the literature are in many instances resolved.
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    Previous studies have demonstrated that an acute bout of static stretching may cause significant performance impairments. However, there are no studies investigating the effect of prolonged stretch training on stretch-induced decrements. It was hypothesized that individuals exhibiting a greater range of motion (ROM) in the correlation study or those who attained a greater ROM with flexibility training would experience less stretch-induced deficits. A correlation study had 18 participants (25 ± 8.3 years, 1.68 ± 0.93 m, 73.5 ± 14.4 kg) stretch their quadriceps, hamstrings and plantar flexors three times each for 30 s with 30 s recovery. Subjects were tested pre- and post-stretch for ROM, knee extension maximum voluntary isometric contraction (MVIC) force and drop jump measures. A separate training study with 12 subjects (21.9 ± 2.1 years, 1.77 ± 0.11 m 79.8 ± 12.4 kg) involved a four-week, five-days per week, flexibility training programme that involved stretching of the quadriceps, hamstrings and plantar flexors. Pre- and post-training testing included ROM as well as knee extension and flexion MVIC, drop and countermovement jump measures conducted before and after an acute bout of stretching. An acute bout of stretching incurred significant impairments for knee extension (-6.1% to -8.2%; p < 0.05) and flexion (-6.6% to -10.7%; p < 0.05) MVIC, drop jump contact time (5.4% to 7.4%; p < 0.01) and countermovement jump height (-5.5% to -5.7%; p < 0.01). The correlation study showed no significant relationship between ROM and stretch-induced deficits. There was also no significant effect of flexibility training on the stretch-induced decrements. It is probable that because the stretches were held to the point of discomfort with all testing, the relative stress on the muscle was similar resulting in similar impairments irrespective of the ROM or tolerance to stretching of the muscle.
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    Delayed onset muscle soreness (DOMS) is a familiar experience for the elite or novice athlete. Symptoms can range from muscle tenderness to severe debilitating pain. The mechanisms, treatment strategies, and impact on athletic performance remain uncertain, despite the high incidence of DOMS. DOMS is most prevalent at the beginning of the sporting season when athletes are returning to training following a period of reduced activity. DOMS is also common when athletes are first introduced to certain types of activities regardless of the time of year. Eccentric activities induce micro-injury at a greater frequency and severity than other types of muscle actions. The intensity and duration of exercise are also important factors in DOMS onset. Up to six hypothesised theories have been proposed for the mechanism of DOMS, namely: lactic acid, muscle spasm, connective tissue damage, muscle damage, inflammation and the enzyme efflux theories. However, an integration of two or more theories is likely to explain muscle soreness. DOMS can affect athletic performance by causing a reduction in joint range of motion, shock attenuation and peak torque. Alterations in muscle sequencing and recruitment patterns may also occur, causing unaccustomed stress to be placed on muscle ligaments and tendons. These compensatory mechanisms may increase the risk of further injury if a premature return to sport is attempted. A number of treatment strategies have been introduced to help alleviate the severity of DOMS and to restore the maximal function of the muscles as rapidly as possible. Nonsteroidal anti-inflammatory drugs have demonstrated dosage-dependent effects that may also be influenced by the time of administration. Similarly, massage has shown varying results that may be attributed to the time of massage application and the type of massage technique used. Cryotherapy, stretching, homeopathy, ultrasound and electrical current modalities have demonstrated no effect on the alleviation of muscle soreness or other DOMS symptoms. Exercise is the most effective means of alleviating pain during DOMS, however the analgesic effect is also temporary. Athletes who must train on a daily basis should be encouraged to reduce the intensity and duration of exercise for 1–2 days following intense DOMS-inducing exercise. Alternatively, exercises targeting less affected body parts should be encouraged in order to allow the most affected muscle groups to recover. Eccentric exercises or novel activities should be introduced progressively over a period of 1 or 2 weeks at the beginning of, or during, the sporting season in order to reduce the level of physical impairment and/or training disruption. There are still many unanswered questions relating to DOMS, and many potential areas for future research.
  • Article
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    The purpose of this study was to investigate the effects of dynamic activity and dynamic activity/static stretching of the gastrocnemius muscle on vertical jump (VJ) performance. Additionally, muscle activity was recorded using electromyogra-phy. Thirteen healthy adults (7 men and 6 women) with a mean age of 26 6 4 years served as subjects. The average jump height and muscle activity from 3 separate maximal VJ attempts were performed at the start of each session to be used as baseline measures using the Kistler force plate and the Noraxon telemetry EMG unit. Subjects then performed 1 of 2 protocols: dynamic activity only or dynamic activity with static stretching. Each protocol was followed by 3 maximal VJ trials. Average VJ height was analyzed using a 2 (time: pre, post) 3 2 (prejump protocol: dynamic activity, dynamic activity + stretching) analysis of variance with repeated measures on both factors. A paired-samples t-test was used to compare the intraday difference scores for EMG activity between the 2 conditions. Jump height was not influenced by the interaction of pre-post and protocol (p = 0.0146. There was no difference for the main effects of time (p = 0.274) and pre-jump protocol (p = 0.595). Gastrocnemius muscle activity was likewise not different for the 2 prejump protocols (p = 0.413). The results from this study imply that the use of static stretching in combination with dynamic activity of the gastrocnemius muscle does not appear to have an adverse affect on VJ height performance. The practical importance concerns the warm-up routine that coaches and athletes employ; that is, they may want to consider including an aerobic component when statically stretching the gastrocne-mius immediately prior to a vertical jumping event.
  • Article
    summary: Most medical professionals, coaches, and athletes consider flexibility training an integral component of any conditioning program. Definitive research will assist in dispelling common misconceptions often associated with flexibility training. The purpose of this article is to provide an update on the latest research regarding flexibility training. (C) 2005 National Strength and Conditioning Association