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Here you will find an article on one exercise
(new one every month). With a detailed analysis of the
muscles used during the exercise and a informative description
of how to both perform and assist in the actual performance
of the exercise.
A full library of all previous exercises
can be found at members online under the sub menu
Exercise:
Hamstring Curls
Client Instruction:
Starting Position
1. Lie in a prone position on an angled leg curl machine
bench
2. Position yourself so that both of your patella clear
the support bench by about 4-5 cm so that they are aligned
with the axis of rotation of the machine.
3. Tighten your abdominals to support your back and grasp
the handles below the bench to keep the upper body fixed
to the bench
Up Phase
4. From this starting position commence bending your knees
and moving your heels towards your bottom
5. Continue the curl until the soles of your feet are pointing
to the ceiling or slightly further towards your hamstrings
Down Phase
6. Pause at the top of the movement and then slowly lower
your legs back to the starting position (just before being
fully extended)
Muscle Analysis
Chart - Dumbbell Front Arm Raise
| Up Phase |
| Joint |
Action |
Contraction |
Muscle Group |
Specific Muscles |
| Knee Joint |
Flexion |
Concentric |
Knee Joint Flexors |
semimembranosus semitendinosus
biceps femoris
(hamstring group) |
| Down Phase* |
| Shoulder Joint |
Extension |
Eccentric |
Knee Joint Flexors |
semimembranosus semitendinosus
biceps femoris
(hamstring group)
|
*In the down phase of the exercise the weight is lowered
slowly with gravity. The muscles that concentrically contracted
to lift the weight are the same muscles that are eccentrically
contracting to lower the weight.
General
Kinesiological Analysis
In a prone hamstring curl the knee joint is
flexed by the concentric contraction of the semi-membranosus,
semitendinosus and the biceps femoris. All three of these
muscles are prime movers in the exercise.
Advanced Kinesiological
Analysis
One muscle that can contribute to this movement, but is more
widely know for plantar flexion of the ankle joint, is the
gastrocnemius. It is possible for the gastrocnemius to contribute
to knee joint flexion due to its origin on the lower posterior
end of the femur. As a consequence of crossing two joints
it has an action on each joint. Its ability to cause knee
joint flexion is limited because its insertion is so far away
from the axis of rotation it possesses a small lever arm.
When the semimembranosus and the semitendinosus contract in
knee joint flexion they can also cause a secondary action
of medial rotation of the knee joint. At the same time as
the biceps femoris is also contributing to knee joint flexion
it is also causing lateral rotation of the knee joint. When
the three muscles work in synergy together they neutralize
this unwanted medial and lateral rotation and cause knee joint
flexion.
When the hamstring curl is performed in a prone position,
there is at times a tendency for clients to lift their bottom
off the bench, so that their abdominals are no longer in contact
with the bench. This movement is caused by the hamstrings
pulling at both ends of their attachments. Both their insertions
and origins are moving at the same time. This can be avoided
by the abdominals contracting statically to prevent this backward
tilt of the pelvic girdle. This paradox occurs more frequently
on a flat bench than an on angled bench.
Exercise Variations
The seated hamstring curl variation compared to the prone
hamstring curl recruits the semimembranosus and semitendinosus
to a greater extent. The biceps femoris (short head) is more
active in the prone hamstring curl. The seated hamstring curls
also evokes a greater response in the sartorius and the gracilis
in contributing to knee joint flexion. Overall, the seated
hamstring curl has the potential to produce a greater hamstring
response than the prone curl. This demonstrates the importance
of training the hamstrings using a variety of hamstring exercises
at both the knee joint and the hip joint.
Stability Ball Exercise Variations
The client lies in a supine position with their heels in
contact with the stability ball. Initially the client contracts
their lower back and gluteals to straighten the trunk and
form a straight line between the heels and the shoulders.
The client will splay their arms out to the side of the body,
horizontal to the trunk. From this starting position, the
client will curl the stability ball underneath their body
by flexing the knee joints. When the knees are flexed to 90
degrees the client will extend the knees and roll the stability
ball back to the starting position.
Disclaimer: No responsibility is accepted for any loss
or damage suffered as a result of the use of the above
information
or any reliance on it. Users should satisfy themselves
as to their own or clients medical and physical condition
before adopting/using
the information or recommendations made. No responsibility
or liability is accepted for any loss or damage suffered
by any person as a result of adopting the above information
or recommendations.
Further information
1300 136 632 Phone +61 02 9212 7185 or Fax +61 02 9211
0002
Suite 505/410 Elizabeth Street Surry Hills 2010 Sydney
Australia
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