Lecture 5 - Hamstring Strains
3 strengthening exercises
'Supine bent knee bridge walk -out' exercise. 'Supine single-limb chair-bridge' exercise. 'Single-limb balance windmill touches with dumbbells' exercise
what is the odd ratio of re-injiry
(The odd ratio of re-injury is 11 times higher!)
when does hamstring strain occur?
When sprinting, the deceleration phase shortens, requiring a higher eccentric activation of the hamstrings to compensate the forward momentum, and the forces that influence the hamstrings may then cause tearing in the muscle-tendon unit Occurs in late forward swing phase of gait cycle
out of these 4 muscle strains, which one has highest reoccurance rate?
hamstring
rate these strains in order of how common they are (most to least) hamstring calf groin quad
hamstring groin quad calf
however, what happens if we stay inactive too long?
hamstring would shrink and scar tissue would form around the tear
why are strains a challenge for both athletes and clinicians?
high incidence rates high re-injury rate slow healing persistent symptoms
what may broad discolouration indicate?
high-grade myotendinous injury or proximal avulsion injury.
when are hip adductors (groin) commonly injured?
in football during turning activities and side foot passing
when are hamstring strains very common?
in sports with acceleration and maximal sprints
when can the stretch % be even greater?
in the final swing during hurdle event when maximum knee extension plus hip flexion occur simultaneously
extrinsic risk factors of hamstring strain
inadequate warm up fatigue dehydration
2 main results
increace in eccentric hamstring torque increase in isometric hamstring strength (no effect on concentric quad strength)
with extension, what indicated possible hamstring strain or tendinopathy?
increasing posterioor thigh pain
what device is used to assess knee strength?
isokinetic dynamometer test
why is this important?
it doesnt cause harm to participant
is a muscle strain linear or angular?
linear (sprains are angular/rotational)
a number of studies have showed that what is a risk factor for sustaining hamstring strain
low hamstring strength
what are skeletal muscles primarily responsible for?
maintaining and changing posture and locomotion
when are hamstring muscles often injured?
most active during running/sprinting which is when they are injured
a hypothesis: this area may be positively related to what?
muscle size and strength
when are hip lexors injured? location?
muscles at the front of the hip for shooting and striking a ball.
where are muscle fibres usually torn
near the muscle-tendon junctions
is there evidence of limb dominance?
no
what exercise is often used as an exercie intenvention for prevention?
nordic hamstring exercise
what usually causes a muscle strain?
overstretching which tears muscle fibres More often happens in eccentric contraction when the muscle is under a linear contraction force but at the same time lengthening
what can we do to check muscle belly rupture?
palpate although location is difficult to identify given deep location of muscles
how to do a bent knee stretch test
patient lie supine hip and knee maximally flexed patient relaxes and examinar slowly and passively extends the knee
how to do a peranen orava (hurdle) test?
patient stands hip flexed to 90 degrees knee fully extended heel on a support
this exercise has to be done progressively based on what?
patients tolerance and improvement
when physically examining, what may be a sign of hamstring strain?
patients walking a stiff-legged gait pattern because this will avoid simultaneous hip flexion and knee extension and so prevents lengthening of the hamstring
when are quads most often injured?
powerful muscles for straightening the knee for running, kicking and jumping
intrinsic risk factors of hamstring strain
previous injury H:Q ratio (agonist antagonist strength imbalance) lack of flexibility older age hamstring msucle weakness ethnicity (black african, caribbean) bilateral asymmetryt (one significantly weaker limb)
strain aka
pulled mscle
what tests can be used to test a hamstring strain?
puranen orava test (hurdle test) bent knee stretch test
what generates more torque, hamstrings or quads? and then how does this look on a graph?
quads quads has higher peak
apart from assessing knee strength, what else is isokinetic dynamometer useful for?
rehabillitation of knee strength at full range
what does a strain cause?
significant time loss - can be career threatening - should be major objective to prevent - need to identify risk factors and injury mechanisms
how do these filaments interact?
slide past each other producing a contraction that changes both length and shape, changing motion and force that can be produced
is ice good or bad?
some have suggested that ice does more harm than good ice is just for pain, doesnt actually help injury
week 12
sport-specific training
what track and field event do hamstring strains most often occur?
sprinting events
what does it test?
strenth of muscle screating body joint motion
what is needed to treat complete rupture?
surgical operations need to suture two parts back together to allow healing
what phase of the gait cycle when running/sprinting, do hamstring strains occur?
terminal swing phase
what is happeneing to the hamstrings in the second half of the swing?
the hamstrings are active and lengthened in preparation for foot contact.
why are muscle fibres usually torn here?
the muscle tendon juncitons experience the highest eccentric load
how does a surgical operation happen?
the procedure starts withthe patients prone on an operating room table. A transverse incision is made at the gluteal crease (fold of the buttock) directly inferior to the ischial tuberosity. the hamstring tendon is then sutured back to the bone. braced with hip orthotic in 30-40 degrees of flexion to limit stress to the surgery site, followed by rehabilitation.
what does the resistance during isokinetic dynamometer testing depend on and why?
the torque the participatnt could generate because flexion and extension speed is fixed
how are MRI and computer tomography (CT) be uesful?
they help precisely define the injury location, degree of damage, number of involved tendons, extent or retraction and chonticity
what happens on day 10-14 of rehab?
toe-touch weight-bearing with crutches.
what is the HC exercise. how was it done?
traidition le curl on HC machine lie flat stomach down keep hips fixed and ankles hooked rest forehaead on bench grab handgrips bring heels up to bottom as fast and forcelly possible to maximise effort in concentric phase then return the load with as lttle effort as possible to minimize loading in eccentric phase
clinical representation of hamstring strain
usually acute, sudden sharp pain in the posterior thigh, often with an audible or palpable pop, during a combination of sudden forceful hip flexion and knee extension in running, jumping and kicking sports. Inability to walk smoothly, and discomfort with sitting Discolouration of the skin beneath due to bleeding is often observed.
is it accurate?
very
what was used to register the highest level of muscle soreness sensed by each subject after each of the initial 10 training sessions?
visual analogue scale
before training period, subjects underwent...
warm up hamstring flex testing strength testing
when is full return to sport allowed?
when the operative leg is 80% of the non-operative leg on isokinetic testing. This usually happens between 6-10 months.
why are x-rays not useful for identifying hamstring strain?
x-rays are often negative unless an avulsion fracture has occured from the ischial tuberosity only looks at bones
advantages of NH disadvantages
can be done anywhere whole team can train at once as strength increases, players may be required to provide support needs knee cushioning
what is the use of dynamic ultrasonography?
can show fluid collections aronf the injured muscle, which represent edema and/or internal bleeding
what happens during weeks 2-5 of rehab?
continued use of the hip orthotic and 25% weight-bearing. Passive exercise with a therapist for the range of motion at the hip at 2 weeks, then active exercise at 4 weeks.
in relation to this, what has been suggested as a risk factor?
A disproportionately small biceps femoris long head proximal aponeurosis
what % can bicep femoris extend to (in an upright standing position) and semimembranosus and semitendinosus
110% 107.5% 108.2%
what is an ideal ratio?
60% : 75%
what speeds are often chosen?
60, 90, 120, 180, 240 degree/s, etc
in football, are more hamstring strains contact or non contact?
91% non contact 7% contact
when is supine bent knee bridge walk out exercise used and what should be avoided is weakness persists in this exercise
After full range of motion is returned, this exercise is for strengthening the hamstring. End range lengthening of the hamstrings should be avoided if weakness persists.
what is the conventinal H:Q ratio?
Concentric hamstring to concentric quadriceps torque ratio
what other ratios are there?
Concentric hamstring to eccentric quadriceps torque ratio Eccentric hamstring to eccentric quadriceps torque ratio
what occurs at week 8 of rehab?
Dynamic training and isometric strengthening (muscles contract without changing length, e.g. wall-sit).
what is the functional H:Q ratio?
Eccentric hamstring to concentric quadriceps torque ratio
week 16
Full isokinetic evaluation at 60, 120 and 180 degree/s.
3 grades of strain and characteristics of the grades
Grade 1: Some fibres are involved. Grade 2: Significant number of fibres are involved. Grade 3: Complete tear/rupture
the study of this hypothesis showed...
High variability of aponeurosis size but not related to muscle size and knee flexor strength.
what are referred to as the older models of rehab?
ICE RICE PRICE POLICE
examples of risk factors
Inadequate hamstring strength (especially lack of eccentric muscle strength) Strength imbalance between hamstrings and quads and/or bilateral hamstring strength deficits Previous injury Poor hamstring flexibility Fatigue Improper warm up
week 10
Isometric strength evaluation performed with the knee at 60 degrees of flexion
signs and symptoms of hamstring strain
It often happens during sprinting. The sprinting athletes would normally limp suddenly after a brief bout of explosive sprinting, and would usually be forced to slow down, stop, and may eventually fall on the ground. Localised stiffness, tightness, discolouration, swelling, redness, and bruising Pain. Sometimes very painful and cannot use the muscle to initiate limb movement to walk at all.
results
NH group - increase in eccentric hamstring torque and isometric hamstring length - increase in H:Q ratio - max concentric quad strength didn't change - hence the increase in H:Q ratio - improvements in the hamstring strength tests - no increases in soreness HC group - no changes
conclusion
NH training for 10 weeks more effectively develops maximal eccentric hamstring strength in well-trained soccer players than a comparable program based on traditional HC A 10-week training regimen with the eccentric strength exercise NH was more effective than a comparable training regimen with regular HC exercise in developing maximal eccentric hamstring strength, the H:Q strength ratio and isometric hamstring strength. Thus, NH exercise may in turn reduce the risk of sustaining a hamstring strain from an injury prevention or rehabilitation point of view it appears that the ideal exercise would be eccentric to decelerate a very high angular knee velocity with maximum force production around 301 of knee flexion. We know of no exercise that fulfills all these criteria, but the NH exercise appears to have a number of advantages when compared with regular leg curls
what does the NHS say we should do to manage a hamstring strain (after surgery)
Once the pain has subsided, do regular gentle hamstring stretches Lie on your back and raise your leg. Keeping your another leg bent with your foot on the floor, pull your leg towards you keeping it straight. Don't hold at the knee level. Repeat with opposite leg. Hold for 10-15 seconds. Perform gentle exercise such as walking and cycling. After exercise, do a buttock stretch. Bring knees up to chest. Cross one leg over the thigh of the other leg. Grasp back of the other thigh with both hands. Pull the other leg toward chest. Repeat with opposite leg. Only return to full level of activity when your hamstring muscles are strong enough.
what is the new model and how is it different?
PEACE & LOVE ice is gone protection elevation avoid anti inflammatories compression education load optimism vascularisation exercise
when is supine single limb chair bridge exercise done?
Patient impending return to sport.
what are patients prescribed and why? after an operation to repair complete rupture
Patients are prescribed aspirin for 4 weeks post-operatively to avoid deep vein thrombosis (DVT) prophylaxis (blood clot forms in deep veins, usually in legs, and cause leg pain and swelling).
what method was used?
RCT
what are NHS guidelines of management of hamstring strain injury (acute management)
Rest: keep your leg as still as you possibly can and avoid physical activity Resting means not running or jumping during the recovery period. Ice: apply ice to your hamstring for about 20 minutes, 2-3 times a day (don't apply it directly to your skin; use a bag of frozen peas wrapped in a tea towel)'. Compression: a compression bandage can help reduce pain and swelling. Elevation: keep your leg slightly raised while sitting to help reduce swelling
how to do exercise
Start with a bridge position, with knee bent and buttock off the ground, leaving only the feet and the upper back supporting the body. Progressively move/slide the feet away from the hips and maintain the bridge position.
how to do supine single limb chair bridge exercise?
Start with one leg on a stationary object. Raise hips and pelvis off the ground, leaving the upper back the only contact with the ground. (Eccentric hamstring strengthening should be progressed toward end range of motion)
how to do single limb balance windmill touches with dumbbells
Start with single-limb stance position with dumbbells overhead. Perform windmill motion under control. End with the dumbbell touching / near the floor
how was strength measured?
Strength was measured as maximal torque on a Cybex dynamometer before and after the training period
what were the two programmes?
The HC exercise was performed in a traditional HC machine The NH exercise is a partner exercise where the subject attempts to resist a forward-falling motion using his hamstrings to maximize loading in the eccentric phase
what is the functional H@Q often uesd to represent and why?
The hamstring is usually lengthened when working, therefore, the functional H/Q ratio is often used to represent the knee / hamstring strength.
what can mode specificity explain?
The lack of eccentric strength improvement in the HC group
differnece betweeen NH and HC exercise programmes
The players in our study who used the NH exercise improved their ability to develop eccentric hamstring torque, and such an improvement can potentially prevent hamstring strains Conversely, it is possible that the regular HC exercise does not protect against hamstring strains, although the players appeared to have become stronger judged by the steady increase in training load
purpose of the intervention
To compare the effects of a 10-week training program with two different exercises - traditional hamstring curl (HC) and Nordic hamstrings (NH), a partner exercise focusing the eccentric phase - on muscle strength among male soccer players compare the effect of a simple eccentric hamstring exercise - Nordic hamstrings (NH) - with the most commonly used concentric strength training exercise - regular hamstring curl (HC)
what is aponeurosis?
a layer of flat broad tendons connecting the muscle to the bone
what was the main finding of the study?
a program of the eccentric strength exercise NH was more effective than the concentric strength exercise HC in developing eccentric hamstring strength measured at 60 degrees s^-1 among well-trained male soccer players
What protein filaments compose a muscle?
actin myosin
what do these old models focus on?
acute managemement but ignore subacute and chronic stages of tissue healing
what else needs to be considered in injury prevention?
angular velocity joint angle joint motion patterns
what may also be introduced at week 6?
aqua therapy
why is the increase in eccentric hamstring strength interesting from an injury persepvtive
as muscle strains are thought to occur during eccentric muscle action
why?
as the mechanical strain is concentrated to a small cross-sectional area
method
before the start of the training period, the subjects underwent a pre-testing protocol of warm-up, hamstring flexibility testing and strength testing After the pre-testing had been completed, the subjects started out on one of the 10-week training protocols
which hamstring muscle are strains most common in?
bicep femoris
where is the greatest stretch in the hamstring?
bicep femoris, which may have contributed to its highest tendency to sustain a strain injury.
what can the iskinetic dynamometer test? and therefore what?
both concentric and eccentric strength therrefore there are several relationships we could use
what happens at week 6 of rehab?
brace removed and the patient is allowed to fully bear weight and begin gait training with isotonic exercise (muscle length changes without additional tension or force development, e.g. squat)
how is knee strength quantified?
by the maximal torques generated by the hamstring and quadriceps, and their ratio, during isokinetic dynamometer test
how lost may recovery take?
days, weeeks or months (for a complete rupture)
what kind of contraction is occuring in the hamstrings in this phase of the gait cycle?
eccentic (lengthening)
what do skeletal muscles produce?
force and motion
what other mechanism, other than sprinting/running, can cause hamstring strain
forceful kicking motion, especially when missing the ball
why is there a huge prevalence of hamstring injuries in soccer?
games have become more physically demanding, more aggressive, higher intensity
