Hip muscle imbalances can cause back and hamstring troubles. Here are two case studies
Muscle imbalance is related to two changes in muscle function:
(1) a tightening of a 'mobiliser' muscle and (2) weakening of a 'stabiliser' muscle. Mobiliser muscles are those that produce movement; they are often big muscle groups with more fast-twitch fibres. Although they produce high power, these muscles have a tendency to shorten. The hamstrings and rectus femoris are the two main mobiliser muscles around the hip joint. In contrast, stabiliser muscles control movement or joint position, often working against gravity. They are smaller, deeper muscles which often have more slow-twitch fibres. They should be well coordinated and have good endurance capacity, though they have a tendency to be under-active and weak. The gluteals are the key stabiliser muscles around the hip joint.
What happens if a mobiliser muscle tightens? There are two main problems associated with tight mobiliser muscles. (i) The limited range of motion can affect movement and place greater stress on the joints and (ii) the tightness in the muscle may inhibit the opposing muscle group through a process called reciprocal innervation. For example, a tight rectus femoris can inhibit gluteus maximus activity.
What happens if a stabiliser muscle weakens? The main problem with weak stabiliser muscles is that they do not have sufficient endurance to hold a position - usually against gravity - for long enough. Sometimes this can be related to a chronic lengthening of the muscle. If this occurs, the force-length relationship within the muscle changes, resulting in an inability of the muscle to hold an 'inner range' position.
The muscle may appear strong on a dynamic test, but is unable to stabilise a joint for a long time holding a static contraction, this being the usual role of a stabiliser muscle. When this chronic lengthening occurs, the stabiliser muscle becomes inactive and joint stability is compromised. Sometimes the adjacent mobiliser muscle becomes overloaded as it tries to compensate for the lack of stability function. For example, lengthened gluteus medius reduces pelvic stability during one-leg support and may overload the tensor fascia lata muscle which can lead to a tightening of the iliotibial band.
How to check
To assess for muscle imbalance one needs to combine flexibility tests for the mobiliser muscles with inner range holding tests of the stabiliser muscles. An example of a flexibility test is the SLR (straight leg raise) test for the hamstrings. The patient lies on his/her back with the knees bent. Take one leg and straighten it at the knee. Place your hand under the lumbar spine and slowly raise the straightened leg. If the hamstrings are flexible enough the leg will raise to about 90 deg until the hamstrings pull on the lumbar spine. A short hamstring will start to pull the lumbar spine much earlier.
An example of an inner range holding test is the prone leg lift for the gluteus maximus. The patient lies on his/her front and bending one knee to 90 deg lifts the thigh a little off the floor. The patient should be able to get a strong contraction of gluteal muscle to do this and be able to hold the static contraction for 60 seconds. If this position places too much strain on the hamstring or low back, or the leg starts shaking, then the patient is unable to recruit the gluteal muscles sufficiently to hold this position.
(The reference for the above description is Christopher Norris 2000, Back Stability, Human Kinetics.)
Take these two examples
The following two case studies are excellent examples of how performing muscle imbalance tests can help you to devise an appropriate rehabilitation programme for patients with back and hamstring trouble. The main advantage of this approach is that the rehab muscle training is specific to the
'To assess for muscle imbalance one needs to combine flexibility tests for the mobiliser muscles with inner range holding tests of the stabiliser muscles.'
function required of that muscle, eg, a stabilising muscle is trained with static and slow controlled exercises emphasising endurance, which is exactly how this muscle would work in daily life and exercise.
Case Study 1: Niggling back pains
Profile: This client suffered from niggling back pains that became very bad if she played any kind of sport. When she came to me her training goals were to improve her back problems as well as to get fitter.
Assessment: We tested her flexibility in most major muscle groups and discovered she was tight in the rectus femoris and adductors. The stability tests showed that she was completely unable to hold the inner range of the gluteus medius and the inner range of the illiopsoas and gluteus maximus both fatigued before 60 seconds. Her posture was also slightly lordotic, which means her pelvis is tilted upwards, extending the lumbar spine.
Analysis: The tight adductors could inhibit the gluteus medius and the tight rectus femoris could inhibit gluteus maximus as well as contribute to her poor posture. In general, the poor endurance of her hip stabiliser muscles meant that any athletic movements were putting too much stress on her back.
Exercise programme: The following exercises were chosen to address the above imbalances and problems. These were completed two-to-three times each week.
Prone leg lifts (Gluteus maximus exercise)
As the athlete lies on her front, with one leg bent at the knee, lift the knee off the floor, focusing on activating the gluteal muscles. Hold the position, squeezing in the buttocks, for 10 secs. Repeat 10 times.
Table top (Gluteal and lumbar stability exercise)
Kneel on all fours with hands under shoulders and knees under hips. Ensure the spine is in 'neutral' and then contract the deep abdominal and pelvic floor muscles to secure this position. Slowly take one leg away behind you keeping the back and pelvis stable. Perform 10 each side slowly, focusing on pelvic stability. If you do this correctly, your back is flat and stable like a table top.
Abductor machine (Gluteus medius exercise)
Using the abductor machine with a light weight you can perform inner range movements. Take the legs out to the widest position and then very slowly pulse the legs in and out 20 times. The movement should be no greater than 4 in. each leg and should be always controlled by the hip muscles, especially on the in phase. Do three sets to build up endurance.
Ball sitting one-leg lifts (Illiopsoas exercise and lumbar stability)
Sit with perfect posture on a gym ball. Contract your deep abdominal muscles to support your lumbar spine and lift one leg off the floor slightly. Hold the leg up, but ensure that you do not lean back or allow the lumbar spine to flex. Hold for 10 seconds and repeat 10 times each side.
Slow ab crunch (Abdominals exercise)
Lying on your back with knees bent. Lift up head so chin is near chest. Contract the pelvic floor to support lower back. Very slowly curl up the shoulders, using only the abdominal muscles. Your pelvis should not tilt, nor should your legs move. Hold the top position for two counts and slowly curl back down. Do not allow your head to go back. Three sets of 20 repetitions.
Hip flexor stretch
Go down to a lunge kneeling position and tilt the pelvis forwards by squeezing the buttocks. Then move your hips forward, stretching the rear hip flexor. Hold for 30 seconds each side.
Sit upright and place the soles of your feet together. Open your knees as wide as possible and hold for 30 seconds.
Some time was spent each session on posture education, in particular learning the correct lumbar spine position while standing, ie, 'neutral', and what this position feels like.
And the results?
After a few weeks this exercise routine produced big improvements. The nagging back pain vanished from daily life and the athlete's muscle function of the hip stabilisers was much improved. In general, her posture and self awareness during movements were also much better.
The next stage for this client is to build on this basic stability improvement and work on more complex exercises to ensure the back is always supported during sports.
Case Study: 2 A dodgy hamstring
Profile: This athlete was suffering from a recurring hamstring strain, which usually flared up as the volume or intensity of training was increased. The goal was to be able to run regularly pain-free.
Assessment: We completed all the flexibility and inner range tests as in Case Study 1. In this case, the athlete only failed two tests: (a) he had tight rectus femoris and (b) his inner range endurance in the gluteus maximus muscle was poor. In addition, his posture was slightly lordotic.
Analysis: The tight hip flexor could be inhibiting the gluteus maximus. Poor stability function of the gluteus maximus could place greater strain on the hamstring during running since the hamstring has to perform both stabilising of the trunk and extending the hip. This is a common cause of hamstring strain.
Exercise programme: The following simple exercise routine was followed five times a week.
Prone leg lifts (Gluteus maximus exercise) As described above.
One-leg squats. (Gluteal and quadriceps functional exercise.) Stand on one leg and keeping the knee in line with the toes squat down, lowering your bum back as though you were sitting on a chair. Go down in control as far as you can and then stand back up. Ensure you stand up fully in between each repetition and achieve good posture. Perform two sets of 10 each leg.
Slow ab crunch. As above.
Hip flexor stretch. As above.
Within two weeks of carrying out this routine, this athlete was suffering no symptoms, his posture and running style had improved due to greater hip flexibility and gluteal support (he was able to maintain a more upright posture) and he was running faster with no pain.