1. Hamstring Strains Pathomechanics
Hamstring strains are common, and the causes are numerous. Because the hamstrings cross two joints. this produces forces and therefore stresses on the hamstrings dependent upon the positions of the hip and knee.

3. Injury Mechanism
1- A quick, explosive contraction that involves a "rapid activity"
2- Imbalance with the quadriceps the hamstring muscles should have 60 to 70 percent of the quadriceps muscles' strength.
3- hamstring muscle fatigue,
4- decreased hamstring range of motion
6- the semitendinous, semimembrasus, and long head of the biceps femoris are innervated from the tibial branch of the sciatic nerve, while the short head of the biceps femoris is innervated by the peroneal branch of the sciatic nerve. This innervations difference likes the short head a completely separate muscle—"a factor implicated in the etiology of hamstring muscle strains"

4. Rehabilitation Concerns
Grade 1. An athlete with a grade 1 hamstring strain may have
1- a normal gait pattern,
2- report some hamstring stiffness at the extremes of hip flexion.
3- complain of sore hamstring muscles, with some pain on palpation and
4- possibly minimal swelling.
5- Lying on front and trying to bend the knee against resistance probably won't produce much pain

5. Grade 2. The athlete with a grade 2 strain
1- can ambulate, but with an abnormal gait. lack heel strike and land during the foot-flat phase of the j gait cycle
2- Resisted knee flexion and hip extension are painful. may report having heard or felt a "pop" during the activity. Flexing the knee against resistance causes pain.
3- Might be unable to fully straighten the knee
4- Passive hip flexion with the knee extended may also produce moderate to severe pain.
5- The athlete's range of motion may be moderately to severely limited in flexion with the knee extended and moderately limited hip flexion with the knee flexed.
6- At the first or second day, moderate ecchymosis may be observed.
7- Palpation may produce moderate to severe pain, and even though a defect and noticeable swelling in the muscle belly may be evident,

6. Grade 3. The athlete with a grade 3 strain
1- will probably not be able to walk without the aid of crutches.
4- may report having heard or felt a "pop* during the activity. Severe pain- particularly during activity such as knee flexion.
5- The sports therapist may detect visible swelling and severe pain on palpation.
6- A noticeable defect may be present, again at the musculotendinous junction.
7- After the first through third days, mod­erate to severe ecchymosis may be observed

7. Rehabilitation Grade 1 (1-2 weeks) Days 1-2
Rest from anything which causes pain.
Apply cold therapy for 15 minutes every 2-4 hours.
Compress - using a tubular bandage.
Knee extensions - in a sitting position straighten the knee as far as possible and then return to a resting position. Repeat for 3-5 minutes. Do not hold the position.

8. Day 3 - onwards
Switch from using ice to heat such as hot packs and warm baths, especially before exercises.
Static hamstring stretch providing they are pain free. Hold for 30 seconds and repeat at least 5 times a day.
Standing hamstring curls progressing to hamstring curls on a weights machine or using a resistance band (3 sets of 20 very light every other day then increase the weight and gradually decrease the repetitions to 4 sets of 10 reps three times a week)
Massage to the muscle every other day. As time progresses and pain allows the massage should become deeper.
As soon as you can do so without pain, begin gentle jogging. Over a period of two weeks gradually increase the duration and speed of the runs.
When you can run for 40 minutes with no problems begin speed work. An example session would be 10 x 60m striding at 50% effort. Two or three days later, 10 x 60m at 70% effort.
Remember to increase slowly and continue stretching, strengthening and sports massage throughout and beyond the rehabilitation process.

9. Grade 2 (2-3 weeks)
Days 1-3
Rest as much as possible.
Apply cold therapy for 15 minutes every 2-4 hours.
Compress - using a tubular bandage

10. Days 4-7:
Alternate use of a hot and cold pack for 5 minutes each over a minute period. Finish on cold to reduce blood flow. Repeat 3 times a day.
Treatment modalities such as TENS and ultrasound may be used to ease pain and reduce swelling.
Begin static stretch (hold stretches for 30 sec's, 5 times a day).
Knee extensions - in a sitting position straighten the knee as far as possible and return to the resting position. Repeat for 3-5 minutes. Do not hold and do not perform if painful
From day three you can do pain free exercises for example Standing hamstring curls and reverse straight leg raises.
Strengthening of the hip and groin muscles using a resistance band or ankle weights (perform 3 sets of 20 reps every other day)
Light Massage may be used provided all bleeding has stopped.

11. Day :
Use heat (hot pack or warm bath) for 10 minutes prior to rehabilitation exercises to help relax the hamstring muscles.
Continue with static stretching.
Light leg curls on a hamstring weights machine or using a resistance band (3 sets of 20 reps at a light resistance three times a week).
Massage every other day.
Swimming or cycling every other day.
If all of these exercises are pain-free, jogging may be introduced at a slow speed for a few minutes at a time.

12. Day 14 onwards:
Continue with static stretching as above.
Continue with hamstring curl exercises, progress by increasing the weight and gradually decreasing the reps to 4 sets of 10.
Continue to have deep massage on the hamstrings on a weekly basis
Introduce dynamic stretching exercises
Introduce eccentric hamstring strengthening .
When you can run for 40 minutes with no problems begin speed work. An example session would be 10 x 60m striding at 50% effort. Two or three days later, 10 x 60m at 70% effort.

13. Dynamic stretching exercises for hamstring muscles

14. Grade 3 (2-3 months)
Days 1-7
R.I.C.E. (Rest, Ice, Compress, Elevate.)
Use crutches. Progress to full weight bearing as soon as possible.

15. Days 7-14
Heat with a hot water bottle, hot bath or ultrasound.
Massage may be used providing all bleeding has stopped. This should be light initially and become deeper over time, as pain allows.
Pain free static contractions (if it hurts don't do it). Use no weight and do 4 sets of 10 reps every day.
Begin static stretch providing there is no pain. Hold for 30 seconds and repeat 5 times a day.
Active hamstring range of motion exercises (pain-free). Lie on the front and bend the knee towards the buttocks.
Strengthening of the hip and groin muscles using a resistance band or ankle weights (perform 3 sets of 20 reps every other day)

16. 2 weeks-1 month
All of the above plus hamstring curls using a resistance band or light ankle weights (3 sets of 20 reps 3 times a week)
Perform shallow squat (no weight) with the feet shoulder width apart (3 sets of reps 3 times a week)
Swimming every other day.
Cycling if pain free.

17. 1 month onwards
All of the above exercises, including gradually heavier resistance and increasing reps to 4 sets of 10.
Start jogging provided it is not painful. An initial slow speed for 5 minutes can be increased gradually in time and pace.
When you can run for 40 minutes with no problems begin speed work. An example session would be 10 x 60m striding at 50% effort. Two or three days later, 10 x 60m at 70% effort.
Eccentric hamstring strength.
Introduce dynamic stretch exercises

18. Criteria for full return to sports
Hamstrings
1- Full ROM at hip at knee
2- Muscle strength and endurance equal to uninvolved side
3- Ability to ambulate (walk, jog, run, hop) without compensation
4- Isokinetic ratios (hamstring/quadriceps) equal to uninvolved leg
5- No residual symptoms after sport-specific functional progression exercises
6- Successful performance of functional tests (e.g., shuttle, sprints/hop test)

19. Quadriceps Muscle Strain
Pathomechanics
The quadriceps muscles are very similar to the hamstrings in that they produce a great deal of force and contract in a "rapid" fashion.
Most strains occur at the musculotendinous junctions.
If the rectus femoris is involved, knee flex­ion range of motion lying prone (hip in extended position) will be severely limited and painful.

21. Injury Mechanism
With no history of direct contact to the quadriceps area, the injury can be treated as a muscle strain.
A quadriceps strain, usually occurs because of a sudden, violent, forceful contraction
An overstretch of the quadriceps, with the hip in extension and the knee flexed, can also cause a quadriceps strain.

22. grade 1 quadriceps strain
1- may complain of tightness in the front of the thigh.
2- The athlete may be ambulating with a normal gait
3- Swelling might not be present, and the athlete usually has very mild discomfort on palpation.
4- With the athlete sitting over the edge of a table, resistive knee extension might not produce discomfort. If the athlete is lying supine with the knee flexed over the edge of a table, resis­tive knee extension may produce mild discomfort, if the rectus femoris is involved.
5- With the athlete lying prone, active knee flexion may produce a full pain-free range of motion, with some tightness at extreme flexion.

23. Rehabilitation Grade 1. 1- Ice, compression,
2- active range of motion exercises
3- isometric strengthening can begin almost immediately.
4- After about 2 days, resistance exercises can be initiated. These exercises might include straight leg raises, isotonic leg extensions (seated and lying), hip flexion (bent knee and straight leg), leg presses and squats (rack and free weights).
5- Stretching of the rectus femoris should be pain-free.

24. Grade 2
1- Probably cannot walk properly. The athlete may present an externally rotated hip to use the adductors to pull the leg
2- Occasional sudden twinges of pain during activity.
3- The knee may be splinted in extension
3- The athlete may notice swelling. Pressing on the muscle causes pain
5- Straightening the knee against resistance causes pain .
6- Unable to fully bend the knee. With the athlete lying prone, active knee flexion range of motion may present a noticeable decrease, in some cases a decrease up to 45 degrees. With a quadriceps strain, any decrease in knee flexion range of motion should classify the injury as a grade 2 or 3 strain.
7- Resistive knee extension, both when sitting and when lying supine, may reproduce pain.

25. Rehabilitation
Grade 2.
1- Icing and crutch walking should begin imme­diately and the muscle should have some form of compression 24 h a day.
2- Electrical stimulation has been used in these first days to limit swelling, inflammation, pain, and minimize the loss of range of motion.
3- Once the athlete is free of pain, isometric quadriceps con­tractions and
4- pain-free range of motion (sitting and ly­ing prone) should progress to increasing range of mo­tion by lying over the edge of a table to further isolate the rectus femoris.
5- Ice should be used along with the above exercises to regain motion.

26. 6- After about a week, if the unweighted exercises just mentioned can be performed without pain, then light resistance can be added.
7- After about a week of pain-free light resistance exercises, the athlete increases the weight for straight leg raises and adds seated and lying knee extensions.
8- Swimming can be added so long as powerful kicking is avoided and bicycling with the cycle seat is high enough that pain is not produced.
9- Passive, pain-free stretching can begin 7-14 days after the injury.

27. Grade 3 quadriceps strain
1- may be unable to ambulate without the aid of crutches and will be in severe pain,
2- with a noticeable defect in the quadriceps muscle.
3- Palpation will usually not be tolerated, and swelling will be present almost immediately.
4- The athlete may not be able to extend the knee actively and against resistance.
5- An isometric contraction will be painful and may produce a bulge or defect in the quadriceps muscle, especially the rectus femoris.
6- With the athlete lying prone, active knee flexion range of motion may be severely limited and might not be tolerated.

28. Rehabilitation Grade 3 1- puts the athlete on crutches for 1-2 weeks.
2- Ice, compression, and electrical stimulation should be used as close to 24h a day as possible. The athlete must have a pain-free range of motion before the compression can be removed.
3- Once pain-free, the athlete can start gentle isometric quadri­ceps contractions and active range of motion exer­cises.
4- Lying, seated and prone active range of motion should be performed. However, take care to avoid overstretching the quadriceps.
5- Straight leg raises can begin, but weight should not be added for days post injury.
6- From this point on, the athlete follows the progression out­lined for grade 2 quadriceps strains.
Full range of motion should be achieved by 4 weeks. Only at this time should quadriceps stretching exercises be implemented.

29. Criteria for full return to sports
Quadriceps
1- Full ROM at hip at knee
2- Muscle strength and endurance equal to uninvolved one
3- Ability to ambulate (walk, jog, run, hop) without compensation
4- Isokinetic ratios (hamstring/quadriceps) equal to uninvolved leg
5- No residual symptoms after sport-specific functional progression exercises
6- Successful performance of functional tests (e.g., shuttle, sprints/hop test)