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Nonuniform Changes in MRI Measurements of the Thigh Muscles After Two Hamstring Strengthening Exercises

Authors:

Abstract

Mendiguchia, J, Garrues, MA, Cronin, JB, Contreras, B, Los Arcos, A, Malliaropoulos, N, Maffulli, N, and Idoate, F. Nonuniform changes in MRI measurements of the thigh muscles after two hamstring strengthening exercises. J Strength Cond Res 27(3): 574-581, 2013. Although many different hamstring strengthening exercises exist, the effect on site specific activation of these exercises on different muscles of the leg is unclear. This study investigated the effects of the eccentric leg curl (LC) and lunge (L) exercises on the biceps femoris long head (BFl), biceps femoris short head (BFs), semitendinosus (ST), semimembranosus (SM), and adductor magnus (AM). Each leg of 11 male professional soccer players was randomly assigned to an LC or L exercise protocol (3 sets of 6 repetitions). Functional magnetic resonance imaging (fMRI) of the subjects' thighs were performed before and 48 hours after the intervention. Fifteen axial scans of the thigh interspaced by a distance of 1/15 right femur length (Lf) were obtained. The fMRI data were analyzed for signal intensity changes. No significant changes were observed in absolute short tau inversion recovery values for the SM and BFs. Significant changes for the ST (∼21-45%) from sections 4 to 10, AM (∼2-13%) at section 4, and BFl (∼ -3 vs. 8%) at section 7 were noted. LC exercises load all the regions of the ST muscle. The L exercises load the proximal regions of the BFl and AM. These findings may have relevance when designing protocols for prevention and rehabilitation of hamstring injuries.
TITLE
Non-uniform changes in MRI measurements of the thigh
muscles following two hamstring strengthening exercises
Authors:
Jurdan Mendiguchia1, Mirian Aranzazu Garrues2, John Barry Cronin3,4, Bret Contreras3,
Asier Los Arcos5, Nikos Malliaropoulos6, Nicola Maffulli7, Fernando Idoate8.
1. Zentrum rehab and performance Center.Department of Physical Therapy.Pamplona,
Spain.
2. Public University of Navarre, Health Science Department .Graduate School for
Health Sciences, Physical Therapy School, Tudela, Spain.
3. Sport Performance Research Institute New Zealand, AUT University, Auckland,
New Zealand
4. School of Biomedical and Health Sciences, Edith Cowan University, Joondalup,
Australia.
5. Club Atletico Osasuna.Pamplona. Spain.
6. National Track & Field Centre, Sports Medicine Clinic of S.E.G.A.S., Thessaloniki,
Greece
7. The London School of Medicine and Dentistry Institute of Health Sciences
Education Centre for Sports and Exercise Medicine Mile End Hospital.
8. Radiology Department, Clinica San Miguel, Pamplona, Spain
Corresponding Author:
Jurdan Mendiguchia1
Zentrum rehab and performance Center
Calle B Nº 23
Department of Physical Therapy
Pamplona, Spain
Jurdan24@hotmail.com
011-34 948229459
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Competing Interest
“ None to declare."
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Abstract
This study investigated the effects of the eccentric leg curl (LC) and lunge (L) on the
biceps femoris (BF), semitendinosus (ST), semimembranosus (SM), adductor magnus
(AM) and gluteus maximus (GM). Each leg of eleven male professional soccer
players were randomly assigned to an eccentric leg curl (LC) or lunge (L) exercise
protocol (3 sets of 6 repetitions). Functional magnetic resonance imaging (fMRI) of the
subjects’ thighs were performed before and 48 hours after the intervention. Fifteen
axial scans of the thigh interspaced by a distance of 1 / 15 of the length of the right
femur (Lf) were obtained from the level of 1/15 Lf to 15/15 Lf . The fMRI data were
analyzed for signal intensity (SI) changes. While no significant changes were observed
in absolute short tau inversion recovery (STIR) values for the semimembranosus and
gluteus maximus, significant changes for the semitendinosus (~21-45%) from sections 4
to 10, adductor magnus (~2-13%) at section 4, and biceps femoris (~ -3 vs 8%) at
section 7 were noted. These two hamstring exercises did not result in a uniform
response (training stimulus) for the same muscles and regions. The ELC exercise was
better suited for loading all regions of the ST muscle, while the L exercise was more
effective for loading the proximal regions of biceps femoris and adductor magnus.
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Introduction
Acute hamstring injuries are the most prevalent muscle injuries reported in sport,
accounting for 6 to 37% of all injuries in Australian Rules football, rugby union,
football, basketball, cricket and track sprinters. [1-8] Appropriate training and
strengthening of the hamstring muscles for many sports is a fundamental focus of
prevention and rehabilitation. Although selective strengthening of the hamstring
muscles has been recommended as a key component in the management of hamstring
injury, [9-13] only limited literature exists to guide clinicians in designing effective
strengthening programs.
The architectures and innervation patterns of the various muscles in the posterior aspect
of the thigh (the biceps femoris muscle long head (BFl), the biceps femoris short head
(BFs), the semimembranosus (SM), and semitendinosus (ST)) differ [14-16], and each
muscle has unique inherent functions. If this were indeed the case, it would be of value
to strength and conditioning coaches as well as clinicians to understand which exercises
preferentially activate different muscle groups, so as programming is guided to better
effect.
Functional magnetic resonance imaging (fMRI) may be a sensitive method for
displaying the physiological changes that occur in muscles activated during exercise, as
it provides detailed anatomical analysis of associated soft tissues, which is lacking in
electromyography (EMG) experiments.[17-22] The short tau inversion recovery (STIR)
sequence is a T2-weighted sequence that suppresses signals from fat and displays
sensitivity in enhancing differences between the water content of tissues. [19-22].
Exercise produces changes in the distribution of water both intra- and inter-cellularly.
The STIR sequence has previously shown to be valuable in the investigation of signal
intensity (SI) changes in muscles after exercise. [19-22]
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MRI has also been used to assess muscle damage following intensive exercise. [23,24]
The T2 value increased following eccentric exercise [18,25-30], and was positively
correlated with plasma creatine kinase (CK) activity, reflecting exercise-induced muscle
damage.[18,23,26,31] Furthermore, previous studies have investigated the intermuscle
differences and intramuscle regional differences of the T2 value between proximal and
distal regions of the muscles of interest. [18,29,32] For example, Kubota et al. [18]
reported that although all hamstring muscles and regions displayed a T2 increase
immediately following eccentric knee-flexion exercise (prone leg-curl machine), the
relationship between the changes of the plasma CK activity and the T2 value of the ST
was not statistically significant until the second day following exercise , which may be
indicative of severe localised muscle damage. These findings have interesting
implications in terms of the time course and effects of different exercises on the
hamstrings.
Some exercises are used to prevent hamstring injuries in elite athletes, [9,11-13] but
fMRI to our knowledge, has not been used to date to investigate muscle damage
and intermuscle and intramuscle regional differences in STIR values. This study
assessed SI changes in the upper thigh muscles using fMRI at 48 hours following a
lunge and eccentric leg curl exercises.
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Materials and Methods
Subjects
Eleven male professional soccer players participated in this study. Participants were
excluded if they had an injury to their legs or back in the preceding 12 months or if they
were unsuitable for fMRI because of foreign metal bodies, electronic implants or
claustrophobia. Before the start of the investigation, each participant’s height, weight,
age, regular exercise program and any previous injuries to the legs were recorded (see
Table 1). Subjects were instructed to avoid strength training activities for the lower legs
and not to use icing or anti-inflammatory medication for the week preceding and the
week of the experiment. Our institutional Ethics Committee approved the study and all
participants gave informed consent to participate in the study.
Insert Table 1 about here
GENERAL INITIAL
CHARACTERISTICS
n MEAN SD
HEIGHT
(m) 11 1.80 0.05
WEIGHT
(kg) 11 74.6 4.5
AGE
(years) 11 22.1 1.8
Table 1: Initial characteristics of subjects.
Procedures
The left and right legs of the subjects were randomly assigned to an eccentric leg curl
(LC) or lunge (L) exercise protocol. The protocol involved 3 sets of 6 repetitions with at
least a two-minute rest between sets. Following the completion of the exercise protocol
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for one leg (e.g LC), a two minutes rest was taken before starting the second exercise
(e.g. L) for the other leg.
Exercise Protocol
For the L exercise, subjects were instructed to step forward a predetermined distance
marked on the floor whilst the trunk remained upright. The length of the step was
standardized for each subject and was equal to the distance from the greater trochanter
to the floor as measured with the subject standing. This normalized distance was chosen
based on pilot testing, in which a comfortable L step length was determined. Subjects
were asked to lower their trunk by flexing their lead and trailing knees simultaneously
to a point where the trail knee was approximately 2 to 3 cm short of contacting the
ground. The lunge was completed when the subjects returned to the starting position.
For the ELC exercise, subjects performed eccentric hamstring curls (Prone Leg Curl
Technogym, Italy) at 120% of their one repetition maximum (1RM). The ELC 1RM
was quantified via a typical incremental load to failure protocol. Once the subject could
not complete two concentric leg curls at the set load this was determined as their 1RM
to which a 20% load, which resulted in the 120% 1RM eccentric load. Subjects were
instructed to lower the weight from a knee-flexed position (100°) to a knee-extended
position (0°) in 3 seconds, maintaining a constant lowering velocity. The subjects kept
their ankle plantar flexed to reduce the contribution of the gastrocnemius muscle.
Subjects were verbally encouraged to exert maximal force at the starting position and to
resist maximally against the knee-extending action throughout the range of motion. The
weight was raised after each eccentric repetition by an examiner, thereby rendering the
exercise an eccentric-only task for the subject.
Imaging Technique
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MR imaging was performed using a 1 T whole body imager (Magnetom Impact Expert;
Siemens-Erlangen, Germany), with the subjects supine with their knee extended
immediately before and 48 hours after the exercise. Once the subject was positioned
inside the magnet, the thighs of both legs were kept parallel to the MRI table and the
feet were strapped together to prevent rotation. The length of the right femur (Lf), taken
as the distance from the intercondylar notch of the femur to the superior boundary of the
femoral head, was measured in the coronal plane.
Subsequently, 15 axial scans of the thigh interspaced by a distance of 1 / 15 Lf were
obtained from the level of 1/15 Lf to 15/15 Lf . Every image obtained was labelled at its
location (i.e. slice 4 being closer to the coxofemoral joint and slice 12 closer to the
knee). Great care was taken to reproduce the same individual Lf each time by using the
appropriate anatomical landmarks [33] For the final calculation of the signal intensity
of each muscle, slices 4 / 15 – 12 / 15 were used for all muscles examined; the two
cranial slices (closer to the hip) and the three distal slices (closer to the knee) were
discarded given the presence of image artifacts. Then fast STIR MR axial images
[repetition time (TR) = 5,300 ms, echo time (TE) = 60ms, inversion time (TI) 115 ms,
flip angle (FA): 180] were collected using a 256 x 256 image matrix, with a 350 mm
field of view and 10-mm slice thickness using a body coil.
The MRI data were evaluated for SI of each hamstring muscle (BF, ST and SM),
adductor magnus (AM) and gluteus maximus (GM). The MR images were transferred to
a personal computer in the Digital Imaging and Communications in Medicine (DICOM)
format and analysed using image manipulation and analysis software (OSIRIX,
University Hospital of Geneva, Switzerland). Individual baseline SI readings, analysed
with a standardized radius of interest (ROI), were established with the preliminary scan
for each participant. The ROI was placed in the same position within the muscle for
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each measurement, avoiding blood vessels and bone, which may have affected the
analysis of the intensity changes. The SI was measured in a circular region of interest
(ROI, 10-30 mm2) within each muscle assessed before and after exercise and a
percentage difference was calculated. The same technician (FIS) performed the MR
imaging scan and the SI measures.
Statistical Analysis
The STIR absolute values were reported as mean ± SD. Given the differences between
exercises utilized in this study, the principal comparison of interest was the within
exercise pre-post changes in absolute values of STIR of the muscles (BF, SM, ST, AM
and GM) for all the different sections (3, 4, 5, 6, 7, 8, 9, 10,11 and 12). To disentangle
the main effects a two factor (time x section) repeated measures ANOVA with post hoc
contrasts was used to determine significant differences between sections. Paired t-tests
were used to determine significant pre-post exercise changes in L and ELC and for the
relative change between the ELC and L exercises. Statistical significance was set at p <
0.05.
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Results
Typical STIR of the right (ELC) and left (L) before and after exercise can be observed
in Figure 1. No statistical differences (p < 0.05) were found in any muscle or section
between left and right legs in the pre-exercise MRI’s. The changes in absolute values
pre and post exercise of the different muscles (BF, SM, ST, AM and GM) and sections
3 to 12 for the ELC and L exercises can be observed in Table 2. The following is a
summary of the main findings from these tables.
Insert Figure 1 about here.
Insert Table 2 about here.
STIR Absolute Values for ELC and L before and after exercise
ELC L
ANOVA
RM p
Muscle
and
Section
TIME n Mean +SD
T-
TEST
p
Muscle
and
Section
TIME n Mean +SD
T-
TEST
P
ST4 Before 11 128.0
915.33 0.048 ST4 Before 11 133.4 13.0 0.718 0.033
After 11 189.0
089.37 After 11 131.00 14.3
ST5 Before 11 134.4
510.71 0.021 ST5 Before 11 132.3 12.3 0.068 0.019
After 11 267.3
6
165.2
5
After 11 139.9 13.4
ST6 Before 11 146.2
720.70 0.005 ST6 Before 11 132.00 15.1 0.057 0.004
After 11 342,4
5
186,4
5
After 11 143.7 18.0
ST7 Before 11 135,9
118,66 0,007 ST7 Before 11 126.3 15.9 0.085 0.005
After 11 321,4
5
183,1
3
After 11 136.3 16.4
ST8 Before 11 130,7
317,82 0,016 ST8 Before 11 124.4 12.9 0.028 0.018
After 11 234,6
4
115,6
4
After 11 134.7 16.1
10
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208
10
ST9 Before 10 131,8
014,70 0,054 ST9 Before 10 126.2 15.2 0.696 0.048
After 10 204,6
0
105,1
0
After 10 127.9 13.6
ST10 Before 10 131,1
012,78 0,029 ST10 Before 10 130.6 9.5 0.268 0.012
After 10 185,3
064,00 After 10 124.00 12.9
BF7 Before 11 157,2
745,35 0,260 BF7 Before 11 147.3 40.2 0.110 0.048
After 11 152,0
041,05 After 11 162.1 43.6
AM4 Before 10 137,1
08,69 0,047 AM4 Before 9 142.1 9.9 0.042 0.152
After 10 145,1
09,71 After 9 164.2 23.5
AM5 Before 11 136,2
79,03 0,143 AM5 Before 11 134.8 6.5 0.002 0.010
After 11 144,0
914,77 After 11 170.2 24.7
AM6 Before 11 140,4
514,10 0,145 AM6 Before 11 137.4 12.8 0.002 0.003
After 11 146,7
312,23 After 11 181.7 31.4
AM7 Before 11 145,1
810,09 0,211 AM7 Before 11 148.0 12.6 0.003 0.001
After 11 140,2
713,56 After 11 172.8 16.1
Table 2: STIR absolute values of muscles before and after exercise. ST=
semitendinosus, BF = biceps femoris, AM= adductor magnus. The number after the
muscle represents the section. ELC= eccentric leg curl. L =Eccentric Lunge, RM=
repeated measures. Significant differences are marked in cursive.
For the semitendinosus, significant changes (~21-45%, Table 2) in the STIR values for
the ELC exercise were noted along the length of the ST belly from sections 4 to 10 (see
Figure 2A); whereas only section 8 was found to differ significantly (p<0.028) from
pre-testing for the L exercise (see Figure 2B). In terms of the adductor magnus,
significant changes were observed for the L exercise proximally (sections 4 to 7,
Figures 3A) (~2-13%) whereas a significant increase in STIR was only found for
section 4 for the ELC exercise (See Figure 3B).
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Insert Figure 2A-2B, 3A-3B.
In terms of biceps femoris, significant differences (p=0,048, see figure 4A and 4B) were
found post exercise for the ELC and L exercise at section 7 (~ -3 vs 8%). No significant
changes were observed in absolute STIR values for the semimembranosus and gluteus
maximus.
Insert Figure 4A and 4B about here.
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Discussion
This study measured whether the hamstring muscles responded in a uniform manner to
two different exercises, as quantified by the absolute changes in the STIR values of
fMRI. It has been assumed previously that during hamstring strengthening exercises,
individual hamstring muscles are activated in a similar manner. However, this is not the
case, as we observed that each hamstring muscle responded differently during the L and
ECL exercises respectively. The mechanics of the exercises used in this investigation
differ in many ways: 1) the ELC is an open kinetic chain exercise with differences in
hip flexion and tibial rotation [34,35] compared to the L which is a closed kinetic chain
exercise;[36,37] 2) the ELC is principally a monoarticular exercise, whereas the L is
biarticular; 3) as a result, the moments around the joints as well as the length-
tension/torque angle relationship of individual muscles will differ; 4) there is no
concentric component in the ELC which is not the case for the L; and, 5) the ELC is
supramaximally loaded at 120% 1RM which is not the case for the L. Given these
differences, it is difficult to ascertain whether a given exercise is ‘superior’ to the other,
and we shall focus on the site specific activation of each exercise and how each exercise
may be used for the conditioning of the hamstring muscle group.
With regards to the ST, it appears that the greatest changes in the MRI measurements
followed the ELC loading, in agreement with previous research. [18,38] The changes
in fMRI measurements of the ST may relate to its architectural characteristics as it has
the longest fascicle length and smallest physiological cross-sectional area (PSCA) of the
hamstring muscles [16], and it is a fusiform muscle compared with more pennate BF
and SM muscles. Muscles containing long fascicles produce forces over large length
ranges and at high shortening speeds, because they have a large number of
simultaneously contracting, serially arranged sarcomeres. [39] Such morphological
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properties of ST may be selectively used to perform eccentric knee flexion more
efficiently.
The region-specific activation within the proximal, middle and distal regions of the
same muscle found in this study were in contrast to the Kubota et al. [18] findings,
where significant differences between proximal and distal regions were detected. This
was explained by the fact that the ST is the only hamstring muscle that was
anatomically partitioned as defined by its architecture and innervation [16]. In addition,
this division into partitions was augmented by the presence of a tendinous inscription
with each partition receiving innervation from one muscle nerve, or from a primary
branch of the nerve [16]. The differences between ours and Kubota et al.’s findings [18]
could be attributed to methodological differences, as we divided the thigh into fifteen
regions while they only divided the thigh into three regions. Only in one instance did
one section (Section 8) of the ST show changes after the lunge exercise.
In the AM, significant changes (section 4,~12%; section 5, ~19%; section 6, ~22%; and
section 7, ~14%s) were observed for the L exercise proximally (sections 4 to 7), as
compared to section 4 ( 5%) for the ELC exercise. The greater evidence of
intramuscular changed of the AM during lunges may result from greater hip extension
moments when the hip is flexed. The large hip extension moment arm in addition to
adduction has been noted previously for this muscle. [40,41] The lesser involvement of
the AM during the ELC may be due to a fixed hip angle position (15º) during the
exercise.
No significant changes in fMRI were observed for the BF after ECL loading. In
contrast, significant absolute changes in STIR values were observed at one region
(Section 7) for the BF after L loading. As T2 values are more sensitive to eccentric
exercise [18,25-30] compared to concentric exercise[26] this study may support
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previous findings where a very short and rapid period of eccentric hamstring contraction
during the forward lunge has been documented .[36,37] Hamstring length depends on
both knee and hip joint angles since the hamstrings are biarticular muslces. The angle of
the hip has more impact on the length of the biceps femoris than the angle of the knee,
[42,43] given the longer moment arm at the hip, and this relationship increases with
increasing knee angle. Hip flexion-extension exercise resulted in greater BF activation
as measured by MRI compared with a hip fixed exercise .[18,38] Given this
information and based on muscle mechanics and physiology, greater BF damage during
lunges may arise from larger internal hip extension moments when the hip is flexed.
It is difficult to ascertain which variables differ between exercises to produce site
specific activation differences. However, greater proximal activation (section 5, 23%;
section 6, 10%; section 7, 8%; and section 8, 7%) is present after the L exercise ( see
figure 3) while minimal or negative changes after ELC exercise (section 5, 11%; section
6, -3%; section 7, -3%; and section 8, -4%) are evident. It is possible that exercise
intensity accounts for the finding that only one region showed significant changes for
the BF. Exercise-induced changes in fMRI vary according to exercise intensity:
previous studies have reported greater SI changes after maximal loads compared to
lower loads. [19,21,22,44-46] To better define this load effect, more research is needed
investigating whether a loaded lunge produces greater changes across the proximal BF
in comparison to the bodyweight lunge.
This study used fMRI to assess the relative damage to lower leg muscles after two
different exercises. Different exercises can increase hamstring strength, [11,47] but
various hamstring exercises do not result in a uniform response, and therefore training
stimulus, for the same muscles and the same regions of the muscles. Because hamstring
strains affect different hamstring muscles, proper exercise selection is crucial to target
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the desired muscle/s. When the goal of a therapeutic intervention is to specifically
strengthen the ST, AM, and/or BF, a progressive resistive training program that
incorporates ELC or L is indicated, as these exercises selectively and effectively
activate the aforementioned muscles. In conclusion, the present study demonstrates that
the ELC exercise is better suited for loading all regions of ST muscle and the L exercise
is more effective for loading the proximal regions of biceps femoris and adductor
magnus.
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... Some studies have reported the distribution of damage among hamstring muscles induced by eccentric exercise. [7][8][9][10] All these studies observed that the semitendinosus (ST) muscle suffers a greater amount of muscle damage than the biceps femoris (BF) and semimembranosus (SM). However, the origin of this inter-muscular heterogeneity and the putative interindividual variability of this distribution of muscle damage remains unknown. ...
... This is in agreement with MRI-based studies using T 2 relaxation time. [7][8][9][10] We also found that, among the 18/24 participants that exhibited substantial muscle damage [i.e., changes in shear modulus after exercise <12.6% based on Le Sant et al. 23 strength loss ~2.0% ± 3.3% of MVC at 48 h after exercise], 16 participants had a larger distribution of damage to ST/Hams than to BF/Hams and SM/Hams ( Figure 2B). ...
Article
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A large inter‐individual variability of activation strategies is observed during hamstring strengthening exercises but their consequences remain unexplored. The objective of this study was to determine whether individual activation strategies is related to the distribution of damage across the hamstring muscle heads (semimembranosus, SM; semitendinosus, ST; biceps femoris, BF) after eccentric contractions. Twenty‐four participants performed 5 sets of 15 maximal eccentric contractions of knee flexors on a dynamometer, while activation of each muscle head was assessed using surface electromyography. Knee flexion maximal isometric strength was assessed before exercise and 48 hours afterwards. Shear modulus was measured using shear wave elastography before exercise and 30 min afterwards to quantify the distribution of damage across the hamstring muscle heads. At 48 h, maximal knee flexion torque had decreased by 15.9 ± 16.9% (P < 0.001). Although no differences between activation ratios of each muscle were found during the eccentric exercise (all P values > 0.364), we reported an heterogenous distribution of damage, with a larger change in shear modulus of ST/Hams than SM/Hams (+70.8%, P < 0.001) or BF/Hams (+50.3%, P < 0.001). A moderate correlation was found between the distribution of activation and the distribution of damage for ST/Hams (r = 0.69; P < 001). This study provides evidence that the distribution of activation during maximal eccentric contractions has mechanical consequences for synergist muscles. Further studies are needed to understand whether individual activation strategies influence the distribution of structural adaptations after a training program.
... As we know, skeletal muscle activation has the potential to influence the functional and structural adaptations to resistance training [131,146,147]. There is evidence to suggest that the hamstrings are activated heterogeneously during a range of different exercises [148][149][150][151][152][153]. Knee dominant exercises (e.g. ...
... Knee dominant exercises (e.g. prone leg curl [150] and NHE [148,149,154,155]) are thought to preferentially activate, as well as result in specific adaptations to chronic exposure to the ST and BF short head. Hip extension exercises (e.g., the stiff-leg deadlift [151] or 45° hip extension exercise [131]) appear to involve to a greater extent and result in more specific adaptations of the SM and BF LH , as well as at the more Fig. 1 An example of a knee/quadriceps dominant movement strategy with upright trunk, resulting in greater knee load. ...
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It is important to optimise the functional recovery process to enhance patient outcomes after major injury such as anterior cruciate ligament reconstruction (ACLR). This requires in part more high-quality original research, but also an approach to translate existing research into practice to overcome the research to implementation barriers. This includes research on ACLR athletes, but also research on other pathologies, which with some modification can be valuable to the ACLR patient. One important consideration after ACLR is the recovery of hamstring muscle function, particularly when using ipsilateral hamstring autograft. Deficits in knee flexor function after ACLR are associated with increased risk of knee osteoarthritis, altered gait and sport-type movement quality, and elevated risk of re-injury upon return to sport. After ACLR and the early post-operative period, there are often considerable deficits in hamstring function which need to be overcome as part of the functional recovery process. To achieve this requires consideration of many factors including the types of strength to recover (e.g., maximal and explosive, multiplanar not just uniplanar), specific programming principles (e.g., periodised resistance programme) and exercise selection. There is a need to know how to train the hamstrings, but also apply this to the ACLR athlete. In this paper, the authors discuss the deficits in hamstring function after ACLR, the considerations on how to restore these deficits and align this information to the ACLR functional recovery process, providing recommendation on how to recover hamstring function after ACLR.
... This was probably to the fact that the first set in VP with a 0.21964 kg/m 2 moment of inertia in this population could be used as a protocol to stimulate the postactivation potentiation responses to obtain a subsequent better performance [46]. When prescribing hamstring strength training exercises, individual hamstring muscles are not activated in a similar manner [47] and changes in response to resistance training occur non-uniformly along the muscle [35,36]. The results of the present study showed that each individual hamstring muscle and regional zone responded differently during hip extension (VP) and knee flexion (LC) exercises. ...
... with a study that did not find changes in BFl after ECC LC [47]. In accordance with Mendez-Villanueva et al. [14], we used a flywheel Leg-Curl device with a high training load in the CON and ECC phases. ...
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The primary aim of the present study was to analyze mechanical responses during inertial knee- and hip-dominant hamstring strengthening exercises (flywheel leg-curl and hip-extension in conic-pulley), and the secondary aim was to measure and compare regional muscle use using functional magnetic resonance imaging. Mean power, peak power, mean velocity, peak velocity and time in the concentric (CON) and eccentric (ECC) phases were measured. The transverse relaxation time (T2) shift from pre- to post-exercise were calculated for the biceps femoris long (BFl) and short (BFs) heads, semitendinosus (ST) and semimembranosus (SM) muscles at proximal, middle and distal areas of the muscle length. Peak and mean power in flywheel leg-curl were higher during the CON than the ECC phase (p<0.01). ECC peak power was higher than CON phase (p<0.01) in conic-pulley hip-extension exercise, while mean power was higher during the CON than ECC phase (p<0.01). Flywheel leg-curl showed a higher T2 values in ST and BFs and BFl (p<0.05), while the conic-pulley hip-extension had a higher T2 values in the proximal region of the ST and BFl (p<0.05). In conclusion, ECC overload was only observed in peak power during the conic-pulley hip-extension exercise. Flywheel leg-curl involved a greater overall use of the 4 muscle bellies, more specifically in the ST and BFs, with a selective augmented activity (compared with the conic-pulley) in the 3 regions of the BFs, while conic-pulley hip-extension exercise selectively targeted the proximal and medial regions of the BFl. Physiotherapists and strength and conditioning coaches should consider this when optimizing the training and recovery process for hamstring muscles, especially after injury.
... Mendiguchia et al. (34) studied posterior thigh muscles of soccer players and showed that MRIs are an effective method to capture the acute post-practice muscular changes through the T2 signal. Meanwhile, Mendiguchia et al. (34) showed greater metabolic activity in recto-femoral muscles, vastus medialis, and gluteus maximus using the MRI T2 map immediately after training using the Pilates Method. ...
... Mendiguchia et al. (34) studied posterior thigh muscles of soccer players and showed that MRIs are an effective method to capture the acute post-practice muscular changes through the T2 signal. Meanwhile, Mendiguchia et al. (34) showed greater metabolic activity in recto-femoral muscles, vastus medialis, and gluteus maximus using the MRI T2 map immediately after training using the Pilates Method. Both studies are similar to the present study, which showed an increase in the T2 map after a series of exercises of the quadriceps muscle, a finding that indicates an increase in metabolic activity of muscle cells. ...
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OBJECTIVES: Menopause marks the end of women’s reproductive period and can lead to sarcopenia and osteoporosis (OP), increasing the risk of falls and fractures. The aim of this study is to evaluate the influence of normal and low bone mineral density (BMD) on muscular activity, observed through inflammatory edema when mapping using magnetic resonance imaging (MRI) on the quadriceps muscle of postmenopausal women. METHODS: This was a cross-sectional study involving 16 older women, who were divided into two groups: osteoporosis group (OG), older women with OP, and control group (CG), older women without OP. The groups were evaluated in terms of nuclear MRI exam before and after carrying out fatigue protocol exercises using an isokinetic dynamometer and squatting exercises. RESULTS: The results of the present study showed that in intragroup comparisons, for both groups, there was a significant increase (p<0.05) in the T2 signal of the nuclear MRI in the quadriceps muscle after carrying out exercises using both thighs. In the intergroup comparison, no statistically significant difference was observed between the OG and CG, pre- (p=0.343) and postexercise (p=0.874). CONCLUSION: The acute muscular activation of the quadriceps evaluated by T2 mapping on nuclear MRI equipment is equal in women with and without OP in the postmenopausal phase. BMD did not interfere with muscle response to exercise when muscle fatigue was reached.
... The HS are considered multifactorial injuries (Mendiguchia et al., 2017) where different risk factors have been identified, some nonmodifiable, such as age (Gabbe et al., 2006;Liu et al., 2012;Orchard, 2001;Timmins et al., 2016), and the existence 45 of a previous hamstring structure injury (Freckleton & Pizzari, 2013;Liu et al., 2012;Malliaropoulos et al., 2011 Q13 Q14 ; Mendiguchia et al., 2012;Orchard, 2001;Timmins et al., 2016); and other modifiable, such as strength imbalances between hamstrings and quadriceps (Croisier et al., 2008;Freckleton & Pizzari, 50 2013;Timmins et al., 2016), muscle weakness (Mendiguchia et al., 2012(Mendiguchia et al., , 2013Timmins et al., 2016), fatigue (Liu et al., 2012;Mendiguchia et al., 2012), reduced range-of-motion (ROM) in hamstring-related joints (hip and knee) (Cejudo et al., 2020;Gabbe et al., 2006;Liu et al., 2012;López-Valenciano et al., 55 2017;Mendiguchia et al., 2012;Timmins et al., 2016 Q15 ; Witvrouw et al., 2003), among others. However, gender influence on these risk factors is unknown. ...
Article
Purpose: The aim of this study was to explore if specific hip and knee range-of-movement (ROM) tests can predict a risk factor for hamstring strain (HS) injury in male and female soccer players. Methods: One hundred amateur soccer players (56 men and 44 women) performed six tests to determine hip and knee ROM: straight leg raise test (SLR), modified Thomas test (TT), hip internal and external rotation (ER), hip abduction and adduction, Nachlas test and Ridge test. A logistic regression analysis was carried out to create a predictive model for HS injuries. Results: The percentage of HS injury was 20.45% and 30.35%, for female and male players. The logistic regression showed a significant model for both genders on the logit of suffering an HS injury with active-SLR and TT variables for females (R2CS = 0.491; R2N = 0.771) and active SLR and ER variables for males (R2CS = 0.623; R2N = 0.882). The predictive models correctly classify 95.5% and 94.6% of cases presenting good sensitivity (77.8% and 88.2%) and full (100%) and high (97.4%) specificity respectively. Furthermore, female players showed a greater ROM than males (p ≤ 0.01). Conclusion: Both female and male soccer players that suffered a HS injury had lower ROM in SLR, NT and RT and higher ROM in the TT that non-injured players. The tests that most likely predict HS injury are SLR and TT in females and SLR and ER in males. Thus, it is suggested to including specific exercises in amateur soccer players training programs to improve hip and knee ROM for injury prevention.
... It has been described that ST is divided into proximal and distal regions according to the architecture and innervation (Woodley & Mercer, 2005). Moreover, these regions have shown different activities during various movements (Hegyi, Csala, Péter, Finni, & Cronin, 2019a;Kubota et al., 2007;Mendiguchia et al., 2013). For instance, the activity level of the distal region was reported to be higher than that of the middle region during hip extension tasks (e.g. ...
Article
Purpose: Muscle hypertrophy can occur non-uniformly in athletes who repetitively perform particular movements, presumably leading to a unique muscle size distribution along the length. The present study aimed to examine if sprinters have unique size distributions within the gluteus and posterior thigh muscles. Methods: Nineteen male sprinters and 20 untrained males participated in the present study. T1-weighted magnetic resonance images of the hips and right thigh were obtained in order to determine whole and regional (proximal, middle, and distal) volumes of the gluteus maximus and individual posterior thigh muscles. Results: The results showed that the volumes of all the examined muscles relative to body mass were significantly larger in sprinters than in untrained males (all P < 0.001, d = 1.40-3.29). Moreover, the magnitude of the difference in relative volume between sprinters and untrained males was different between the regions within the gluteus maximus (P = 0.048, partial η2 = 0.187), semitendinosus (P = 0.004, partial η2 = 0.331), and adductor magnus (P = 0.007, partial η2 = 0.322), but not within the other posterior thigh muscles (P = 0.091-0.555, partial η2 = 0.025-0.176). The magnitude of the difference in relative volume between the sprinters and untrained males was greatest in the distal regions within the gluteus maximus and semitendinosus, while the proximal region within the adductor magnus. Conclusion: These findings indicate that sprinters have unique size distributions within the gluteus maximus, semitendinosus, and adductor magnus, which may be attributed to their competitive and training activities.
... 2 In the NHE, the stress on the hamstring muscles is increased over the range of motion due to the increasing lever arm, making the exercise especially heavy at long muscle lengths. Furthermore, it has been indicated that different exercises have different regional activating patterns, 4 with the NHE having a homogenous regional activating pattern, with the semitendinosus being more activated in the proximal region, while the biceps femoris is more activated in the distal region. 5 This could be of importance since most hamstring injuries in professional soccer occur in the long head of the biceps femoris. ...
Purpose: The Nordic hamstring exercise (NHE) has been shown to considerably reduce hamstring injuries among soccer players. However, as the load in the NHE is the person's own bodyweight, it is a very heavy exercise and difficult to individualize. The flywheel inertial leg curl (FLC) could be an alternative since the eccentric overload is based on the amount of work produced in the concentric movement. Therefore, the primary aim of this study was to compare the activation in the hamstrings at long muscle lengths in the NHE and the FLC in amateur soccer players. Methods: Fifteen male amateur soccer players performed 5 repetitions in each exercise in a randomized and counterbalanced order. The concentric and eccentric movements were divided into lower and upper phases. Surface EMG was measured distally, proximally, and in the middle, at both muscles. Results: In the lower phase in the eccentric movement, there were no significant differences between the 2 exercises (P = .101-.826). In the lower concentric movement, the FLC led to higher activation in all parts of both the biceps femoris (31%-52%, P < .001) and the semitendinosus (20%-35%, P = .001-.023). Conclusion: Both exercises activated the hamstrings similarly at long muscle lengths during eccentric contractions (Nordic hamstring, nonsignificantly higher). However, when performing concentric contractions, the FLC induced higher activations. Therefore, the FLC could be a useful alternative to the NHE and particularly suitable for weaker athletes before progressing to NHE.
... 6-7). The largest T 2 increase in the ST is in line with previous studies, which conducted similar eccentric leg curl exercises and measured prolonged T 2 changes (38)(39)(40), and also aligns with the abovementioned preferential activation/ hypertrophy in the ST after knee-dominant exercises (32,34). It is not clear why the ST is prone to damage, but this may be partly attributable to its unique morphology such as being a fusiform muscle (41) and having high regional fiber length heterogeneity (42,43). ...
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The bi-articular hamstrings are lengthened more in a seated (hip-flexed) than prone (hip-extended) position. Purpose: We investigated the effects of seated vs prone leg curl training on hamstrings muscle hypertrophy and susceptibility to eccentric exercise-induced muscle damage. Methods: Part 1: 20 healthy adults conducted seated leg curl training with one leg (Seated-Leg) and prone with the other (Prone-Leg), at 70% one-repetition maximum (1RM), 10 reps/set, 5 sets/session, 2 sessions/week for 12 weeks. MRI-measured muscle volume of the individual and whole hamstrings (WH) was assessed pre- and post-training. Part 2: 19 participants from Part 1 and another 12 untrained controls (Control-Leg) performed eccentric phase-only leg curl exercise at 90% 1RM, 10 reps/set, 3 sets for each of the seated/prone conditions with each leg. MRI-measured transverse relaxation time (T2) and 1RM of seated/prone leg curl were assessed before, 24, 48, and 72 h after exercise. Results: Part 1: Training-induced increases in muscle volume were greater in Seated-Leg vs Prone-Leg for the WH (+14% vs +9%) and each bi-articular (+8-24% vs +4-19%), but not mono-articular (+10% vs +9%), hamstring muscle. Part 2: After eccentric exercise, Control-Leg had greater increases in T2 in each hamstring muscle (e.g. semitendinosus at 72 h: +52%) than Seated-Leg (+4%) and Prone-Leg (+6%). Decreases in 1RM were also greater in Control-Leg (e.g. seated/prone 1RM at 24 h: -12%/-24%) than Seated-Leg (0%/-3%) and Prone-Leg (+2%/-5%). None of the changes significantly differed between Seated-Leg and Prone-Leg at any time points. Conclusion: Hamstrings muscle size can be more effectively increased by seated than prone leg curl training, suggesting that training at long muscle lengths promotes muscle hypertrophy, while both are similarly effective in reducing susceptibility to muscle damage.
Article
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This study aimed to investigate the influence of the task type on the relative electromyography (EMG) activity of biceps femoris long head (BFlh) to semitendinosus (ST) muscles, and of proximal to distal regions during isometric leg-curl (LC) and hip-extension (HE). Twenty male volunteers performed isometric LC with the knee flexed to 30° (LC30) and 90° (LC90), as well as isometric HE with the knee extended (HE0) and flexed to 90° (HE90), at 40% and 100% maximal voluntary contraction (MVIC). Hip position was neutral in all conditions. EMG activity was recorded from the proximal and distal region of the BFlh and ST muscles. BFlh/ST was calculated from the raw root-mean-square (RMS) amplitudes. The RMS of 40% MVIC was normalized using MVIC data and the proximal/distal (P/D) ratio of normalized EMG (NEMG) was calculated. The BFlh/ST ratio was higher in HE0 than in LC90 during MVIC and 40% MVIC (p<0.05), and was higher in HE90 than in LC90 (p<0.05) during 40% MVIC at the proximal region, whereas no difference was observed between HE0 and LC30. There was no inter-task difference in BFlh/ST ratio in the distal region. Furthermore, the P/D ratio was higher in LC90 than in LC30 and HE0 (p<0.05) in BFlh and ST muscles, and was higher in HE90 than in LC30 and HE0 (p<0.05) in BFlh during 40% MVIC. However, there was no difference in P/D ratio between LC30 and LC90, and HE0 and HE90. This showed that there was no task-dependent difference in the EMG activity of the BFlh muscle relative to the ST muscle between prone hip extension and prone knee flexion when the knee joint was set at an equivalent angle. Similarly, there was no task-dependent difference in the NEMG of the proximal region relative to the distal region in BFlh and ST muscles during 40% MVIC.
Chapter
Hamstring strain injury often results in neuromuscular performance deficits that persist beyond rehabilitation and the return to full training and competitive sport. It seems appropriate to address these deficits as a part of a sport-specific training program which primarily aims to enhance performance. Prolonged deficits in horizontal ground reaction forces in sprinting, repeat sprint performance, knee flexor eccentric strength and biceps femoris long head fascicle lengths have been observed in multiple studies of hamstring strain injury. Why such deficits persist beyond the return to sport is not known, although persistent neuromuscular inhibition of the injured muscles has been proposed. There is limited and mixed evidence for sprint running kinematic (technique) differences between previously injured and uninjured limbs or athletes, although more work in this area seems warranted. While there is some uncertainty about the optimal mix of methods for addressing the aforementioned deficits, sport-specific running programs in conjunction with continued monitoring of acceleration phase sprint performance and repeated sprint ability seem appropriate. Heavy strength training with at least some eccentrically biased exercises is also recommended to address deficits in eccentric strength and muscle fascicle lengths.
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Effects of strength training (ST) for 21 wk were examined in 10 older women (64 ± 3 yr). Electromyogram, maximal isometric force, one-repetition maximum strength, and rate of force development of the leg extensors, muscle cross-sectional area (CSA) of the quadriceps femoris (QF) and of vastus lateralis (VL), medialis (VM), intermedius (VI) and rectus femoris (RF) throughout the lengths of 3/12–12/15 (Lf) of the femur, muscle fiber proportion and areas of types I, IIa, and IIb of the VL were evaluated. Serum hormone concentrations of testosterone, growth hormone (GH), cortisol, and IGF-I were analyzed for the resting, preexercise, and postexercise conditions. After the 21-wk ST, maximal force increased by 37% ( P < 0.001) and 1-RM by 29% ( P < 0.001), accompanied by an increase ( P < 0.01) in rate of force development. The integrated electromyograms of the vastus muscles increased ( P < 0.05). The CSA of the total QF increased ( P < 0.05) throughout the length of the femur by 5–9%. The increases were significant ( P< 0.05) at 7/15–12/15 Lf for VL and at 3/15–8/15 Lf for VM, at 5/15–9/15 for VI and at 9/15 ( P < 0.05) for RF. The fiber areas of type I ( P < 0.05), IIa ( P < 0.001), and IIb ( P < 0.001) increased by 22–36%. No changes occurred during ST in serum basal concentrations of the hormones examined, but the level of testosterone correlated with the changes in the CSA of the QF ( r = 0.64, P < 0.05). An acute increase of GH ( P < 0.05), remaining elevated up to 30 min ( P < 0.05) postloading, was observed only at posttraining. Both neural adaptations and the capacity of skeletal muscle to undergo training-induced hypertrophy even in older women explain the strength gains. The increases in the CSA of the QF occurred throughout its length but differed selectively between the individual muscles. The serum concentrations of hormones remained unaltered, but a low level of testosterone may be a limiting factor in training-induced muscle hypertrophy. The magnitude and time duration of the acute GH response may be important physiological indicators of anabolic adaptations during strength training even in older women.
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