Several sports and physical activities which involve a high demand of
excessive stretching or hamstring injuries vary greatly from one
another, each consisting of different injury types, location and size. Because
of this, offering the proper recommendations regarding rehabilitation and
prognosis about healing time and return-to-play can be challenging. Depending
on the biomechanical cause, region and severity of the soft tissue injury, it’s
been previously suggested that return-to-play timescales can differ between
28-51 days following acute hamstring injuries. However, this has been an
ongoing issue within the field of many healthcare professionals.
sprinting, including kicking, sliding and split
positions, have been determined to increase the risk of acute hamstring
injuries among athletes. Acute
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When returning to the individual’s specific sport, the risk of re-injury
is generally higher within the first 2 weeks. This occurs due to initial
hamstring weakness, fatigue, lack of flexibility and strength imbalance between
the eccentric hamstrings and the concentric quadriceps. The highest
contributing factor though, is believed to be linked to an inadequate
rehabilitation program, which may correspond with the premature return to
physical activity. New evidence has shown the benefits of primarily utilizing
eccentric strengthening exercises in hamstring rehabilitation performed with
increased loads for longer musculotendinous lengths.
The semitendinosus, or ST, the semimembranosus, or SM, and the biceps femoris
long and short heads (BFLH and BFSH) are part of the hamstring muscle group. They
primarily function with the extension of the hip and flexion of the knee as
well as providing multi-directional stability of the tibia and pelvis. These
three muscles which make up the hamstring muscle group, cross the posterior
aspect of both the hip and the knee joints, making them bi-articular. As a
result, they are consistently responding to large mechanical forces created by upper
limb, trunk and lower limb locomotion as a means of concentric and eccentric
mobilization. During sporting activities, these forces will tend to increase,
augmenting the frequency of injury.
In a study conducted at the University of Melbourne, biomechanical
analysts measured the musculotendinous strain, velocity, force, power, work and
other biomechanical loads experienced by the hamstrings throughout the course
of over-ground sprinting and compared the biomechanical load across each
individual hamstring muscle.
Basically, the hamstrings are subjected to a stretch-shortening cycle
when sprinting, with the lengthening phase occurring during the terminal swing
and the shortening phase commencing just before each foot strike, continuing
throughout the stance. Then, the biomechanical load on the bi-articular
hamstring muscles were determined to be stronger during the terminal swing.
BFLH had the greatest musculotendinous strain, ST displayed considerable
musculotendinous lengthening velocity, and SM produced the highest musculotendinous
force and both absorbed and generated the most musculotendinous power. Similar
research also distinguished peak musculotendinous strain as a large contributor
to eccentric muscle damage or injury, most commonly acute hamstring injuries, instead
of peak muscle strength. This is why eccentric strengthening is often a
rehabilitation recommendation for acute hamstring injuries.
Location and Severity of Injury
In a randomized
and controlled study on professional Swedish football players, 69 percent of
injuries were primarily located in BFLH. In contrast, 21 percent of the players
experienced their primary injury within SM. While the most common,
approximately 80 percent, suffered a secondary injury to ST as well as BFLH or
SM, a clear 94 percent of the primary injuries were found to be of the
sprinting-type and were located in the BFLH, whereas, SM was the most common location
for the stretching- type of injury, accounting for approximately 76 percent.
These findings were supported in another similar article.
Classifying a soft tissue injury, including acute hamstring injuries, depends
largely on a grading system ranging from: I, mild; II, moderate; and III,
severe. The different classifications offer useful descriptions for each type
of soft tissue injuries between healthcare professionals during clinical
diagnosis and prognosis following an acute injury. A mild grading describes an
injury where a small quantity of muscle fibres are involved with minor
swelling, discomfort, minimal or no loss of strength or restriction of
movement. A moderate grading describes an injury with a significant tear of
several muscle fibres, pain and swelling, reduced power and limited mobility. A
severe grading describes an injury where a tear has occurred across an entire
cross section of muscle, commonly a tendinous avulsion, and a surgical opinion may
be required. It has also been utilized as a classification system for
radiological methods, such as magnetic resonance imaging, or MRI, or ultrasound,
if required for complementary confirmation of diagnosis.
The British Athletics Medical Team proposed a new injury classification
system for improved diagnostic accuracy and prognostication based on MRI features
Determining accurate return-to-play timescales following many acute
hamstring injuries has been proven to be difficult. For example, injuries
involving an intramuscular tendon or aponeurosis with adjacent muscle fibres generally
need shorter recovery periods than those involving a proximal free tendon
and/or MTJ.
There’s also been connections between MRI findings according to the
region of the injury and return-to-play. Particularly, it has been hypothesized
that the shorter the distance between the proximal pole of the injury and the
ischial tuberosity found on MRI evaluations similarly determined by the
presence of oedema, the longer the time to return will be. In the same manner,
the length of oedema shows a similar effect on recovery time. The longer the
length, the longer the recovery. Additionally, the position of peak pain
simultaneously following acute hamstring injuries are also associated with
increased recovery periods.
Furthermore, there have been attempts to clarify the connection between the
grading of acute hamstring injuries and return-to-play. In a prospective cohort
study on 207 professional football players with acute hamstring injuries, 57
percent were identified as grade I, 27 percent were identified as grade II, and
only 3 percent were identified as grade III. The athletes with grade I injuries
returned to play within an average of 17 days. The athletes with grade II
injuries returned within 22 days and those with grade III injuries returned
approximately within 73 days. According to the study, 84 percent of these
injuries affected the BF, 11 percent the SM, and 5 percent the ST. However,
there was no significant difference in lay-off time for injuries to the three
different muscles. This has been compared to 5-23 days with grade I-II
injuries, and 28-51 days for grade I-III in other studies respectively.
Rehabilitation for Acute Hamstring Injuries
Various
researchers have previously argued the benefits of eccentric strengthening
following acute hamstring injuries against concentric strengthening when
focusing to reduce timeframes for return-to-play. The bottom line of this
argument is that with the majority of acute hamstring injuries occurring during
eccentric loading, the rehabilitation should be similar to the specific
circumstance which caused the injury in the first place. One study showed a
significant difference between an eccentric and concentric rehabilitation
program following acute hamstring injuries in elite and non-elite football
players.
The randomized and controlled clinical trial conducted on 75 football
players in Sweden, demonstrated that using eccentric strengthening programs
rather than concentric strengthening programs, reduced the time to
return-to-play by 23 days, regardless of the type of injury or the site of
injury. The result showed the number of days to return to full– team training
and availability for match selection.
Furthermore, two rehabilitation protocols were utilized five days
following the injury. All players had sustained a sprinting-type injury as a
result of high speed running or a stretching-type injury as a result of high
kicking, split positions and glide tackling. Certain criteria were excluded for
the study, including previous acute hamstring injuries, trauma to the posterior
thigh, ongoing history of low back complications and pregnancy.
All players were subjected to an MRI analysis 5 days following the
injury, in order to expose the severity and area of injury. A player was
considered to be fit enough to return to full-team training using a test known
as the active Askling H-test. A positive test is when a player experiences any
insecurity or apprehension when performing the test. The test should be
completed without full dorsiflexion of the ankle.
Approximately 72 percent of players sustained sprinting-type injuries,
while 28 percent experienced stretching-type injuries. Of these, 69 percent
suffered injury to the BFLH, whereas 21 percent were located in the SM.
Injuries to ST were only sustained as secondary injuries, approximately 48
percent with the BFLH and 44 percent with the SM. In addition, 94 percent of
the sprinting-type injuries were located in the BFLH while the SM was the most
common location for the stretching-type injury, accounting for about 76 percent
of the injuries.
The two rehabilitation protocols used were labelled the L-protocol and
the C-protocol. The L-protocol focused on loading the hamstrings during
lengthening and the C-protocol consisted of exercises with no emphasis on lengthening.
Each protocol utilized three exercises which could be performed anywhere and
were not dependent of advanced equipment. They also aimed at targeting
flexibility, mobilization, trunk, and pelvic and/or muscle stability as well as
specific strength training to the hamstrings. All were performed in the
sagittal plane with speed and load progression.
Conclusion of Study
The time to return was determined to be significantly shorter in the
L-protocol as compared to the C-protocol, averaging 28 days and 51 days
appropriately. Time to return was also significantly shorter in the L-protocol
than in the C-protocol for acute hamstring injuries of both sprinting-type and
stretching-type as well as for injuries of different injury classification. However,
there still remains question over whether the C-protocol is specific enough for
hamstring activation to create a legitimate comparison.
C-Protocol
Standing Contract/Relax Hamstring Stretch (2x a day, 3 sets x 4 reps)
Standing Cable/Resistance Band Hip Extension (1x a day, 3 sets x 6 reps)
Supine Single-leg Pelvic Lift (Once every 3rd day, 3 sets x 8 reps)
L-Protocol
The Extender (2x a day, 3 sets x 12 reps)
The Diver (Once every other day, 3 sets x 6 reps)
The Glider (Once every 3rd day, 3 sets x 4 reps)
Chiropractic Care for Acute Hamstring Injuries
Aside from the above mentioned rehabilitation protocols, many athletes who’ve
suffered acute hamstring injuries, as well as other types of injuries, have
found relief from their symptoms with a soft tissue specialist, or a
chiropractor. Chiropractic care focuses on numerous musculoskeletal injuries
including a variety of injuries and conditions associated with the nervous
system. A chiropractor will use several rehabilitation techniques, most
commonly spinal adjustments and manual manipulations, to carefully restore the individual’s
natural mobility, flexibility and strength after experiencing an injury,
helping to decrease their symptoms of pain and discomfort. Additionally, a soft
tissue specialist will generally recommend a series of appropriate exercises
and stretches to speed up the rehabilitation process. Chiropractic treatment
not only treats existing injuries, it can also be used to prevent a variety of
sports injuries, including acute hamstring injuries.
Fortunately for athletes, after experiencing an injury or even if there’s
no current injury, there are several effective methods which could be used to
help alleviate the symptoms as well as ensure the athlete returns to their
specific sport of physical activity as soon as possible without the risk of
re-injury.
Preventing Sports Injuries
By Dr. Alex Jimenez
