Hamstrings Intro

Hamstrings

Often Overlooked
The posterior muscles of the thigh are
often overlooked by many weight-training
enthusiasts. Even those trainees who devote
additional time to their leg training so
as to include isolation work on their quadriceps,
frequently neglect to include hamstring
movements into their leg exercise
portfolio. It seems that many weightresistance
trainees apply the “out-of-sightout-
of-mind” adage to their leg training. It
is much more encouraging to work on the
quadriceps where the deep cuts and crevices
can be readily admired. The hamstrings
are not as visible, and thus they require
more diligence on the part of the trainee to
provide proper development. From a tangible
perspective, the “hams” are not called
upon as prominently as the quads in performing
various athletic movements.

However, neglecting the hamstrings
reduces the trainee’s ability to fully develop
their legs. No trainee would ever think of
building only their biceps and not devoting
any attention to their triceps why is it then
that it can be assumed that proper and thorough
leg development can be accomplished
by placing emphasis on only the
anterior thigh and leaving the posterior
thigh untouched?

The benefits of providing for balanced
development of the legs can be realized
from an injury reduction perspective as
well. How many times have you heard of an athlete pulling their hamstrings? In fact I would be willing
to bet that the first mention you heard of the hamstring muscles (outside of the gym), was in reference
to an injury. Sprinters for example, who have built up their quadriceps through their running,
undergo the risk of pulling their weaker hamstrings due to the imbalance of strength.

While running encourages the development of the quadriceps it should be noted that the hamstrings
work in synergy with the quads. If the frontal thigh muscles are developed well beyond the
level of the posterior thigh muscles the posterior muscles become highly- vulnerable to injury risk.
From all perspectives, it makes sense to offer equal devotion to both the anterior and posterior regions
of the thigh.

Location and Function
The posterior region of the thigh is comprised of three main muscles all of which cover both the
knee and the hip joints. Since the hamstrings cross two joints they provide a function at each of
those joints. They serve as extensor of the thigh at the hip joint and flexors of the lower leg at the
knee joint.

Semitendinosus (A)
Location
Originates from the ischial tuberosity of the posterior hip and inserts on the medial surface of
the superior portion of the tibia at the knee.

Function
In addition to providing for hip joint extension and knee joint flexion, the semitendonosous is
also involved in medial rotation of the tibia.

Semimembranosus (B)
Location
Originates on the ischial tuberosity of the posterior hip and inserts on the posterior portion of
the medial condyle of the tibia at the knee joint.

Function
The Semimembranosus is also involved in medial rotation of the tibia.

Biceps Femoris (C)
Location
The biceps femoris of the posterior thigh is similarly constructed to the biceps femoris of the anterior
upper arm in that the muscle has two distinct (long and short), heads. The long head originates
on the ischial tuberosity where it shares a common tendon with the semitendonosous which crosses
at the hip joint. The short head originates from the lateral edge of the linea aspera alongside the femur
bone of the upper leg and the supracondyle region located on the proximal (inside) area of the
femur. Both the long and short heads of the biceps femoris combine via a single tendon and insert
on the head of the fibula of the lower leg.

Function
Both the long and short heads are involved in the action of leg flexion at the knee joint and are
also involved in the lateral rotation of the leg during knee flexion. It should be noted that because the
short head of the biceps femoris does not cross the hip joint it serves no function in hip joint activity.

Muscle Activation
Unlike the quadriceps muscles, the hamstring muscle group is not readily called upon during
many events involving physical activity. While the “quads” are called into action during such activities
as the ascending and descending of stairs or in the relatively simple task of walking, the hamstrings
relatively speaking lay mostly dormant with the result being that the muscles of the posterior thigh
are not nearly as developed as the quadriceps. As a consequence of their reduced activity, whenever
the hamstrings are called upon during movements requiring their high activation, they become correspondingly
highly susceptible to injury. It is important to realize the level of caution that must be
applied to hamstring training in order to stimulate growth and development while at the same time
reducing the risk of injury to this highly-vulnerable muscle group. As a manner of general approach,
the trainee would be well advised to work with light resistance and to utilize slow speed-of- contraction
movement applications featuring full range-of-motion contractions. In this report we will be
analyzing three hamstring movements. Two movements will feature knee joint flexion (lying and
standing leg curls) and one will highlight a stretching action of the posterior thigh (deadlift).