by Mcleod Ian
At the knee, a hinge joint, two primary movements occur. Flexion is the process of pulling the heel to the buttocks, and extension is straightening the knee from a flexed position. Four movements take place at the ankle joint. The process of pointing your toes, as you do in a tight streamline, is plantarflexion. Lifting your toes off the ground and toward your shin is called dorsiflexion. Rolling your ankle inward so that the bottom of your foot faces the midline of your body is inversion. Finally, eversion involves twisting your foot outward as you would before initiating a breaststroke kick.
The muscles of the leg can be categorized as those that act on the hip and knee and those that act on the ankle. The thigh and hip muscles can further be categorized into the following groupings: anterior, medial, gluteal, and posterior. Within the anterior grouping are seven muscles. The iliopsoas (figure 7.1 on page 142) is a deep muscle that arises from the anterior aspect of the lumbar vertebrae and the inner aspect of the pelvis and then crosses the hip joint to attach to the proximal femur. The primary movement generated by the iliopsoas is hip flexion. The quadriceps femoris, the largest muscle group in the body, is divided into four separate muscles that are named according to their point of origin. The rectus femoris, the only one to cross both the hip and knee, originates from the anterior aspect of the pelvis. The vastus lateralis arises from the lateral aspect of the femur, the vastus medialis arises from the medial aspect of the femur, and the vastus intermedius is in the middle. All four muscles have a common insertion on the anterior aspect of the tibia through the patellar tendon and function to extend the knee. Because the rectus femoris crosses the hip joint, it also functions as a hip flexor. The tensor fasciae latae (TFL) runs from the anterior aspect of the pelvis to combine with the iliotibial band (IT band), a thickened band of fascial tissue that runs down the lateral thigh. It then inserts on the lateral aspect of the tibia just below the knee joint. The primary actions of the TFL are hip flexion, abduction, and internal rotation. The final muscle of the anterior group is the sartorius, which is a long straplike muscle that runs diagonally from the anterior pelvis to the medial aspect of the tibia. Its primary actions are to flex, abduct, and externally rotate the hip.
The medial grouping can be divided into the adductor muscle family and two additional muscles that lie in close proximity. The adductor family is composed of three muscles (adductor magnus, adductor longus, and adductor brevis), which all arise from the inferior portion of the pelvis near the midline of the body and attach to the medial aspect of the femur. As the name implies, the primary function of this muscle family is hip adduction. Just superior to the adductors is the pectineus, which also originates from the inferior pelvis near the midline of the body and then inserts along the medial aspect of the femur. Besides assisting the adductors, the pectineus also flexes the hip. The gracilis is the most medial and inferior. It has the same origin as the other muscles but crosses the knee to attach on the medial aspect of the tibia just below the knee joint. Besides adducting the hip, the gracilis is also a secondary flexor of the knee.
Figure 7.1 Muscles of the front of the legs.
The gluteal group contains the three gluteal muscles and a collection of six deep rotators. The gluteus maximus (figure 7.2), the largest and most superficial of the gluteal muscles, arises from the posterior half of the pelvis and a portion of an adjacent bone called the sacrum. It then crosses the hip joint to combine with the IT band, also attaching to a small portion of the femur. The main action of the gluteus maximus is extension of the hip. It also assists other muscles in the region with external rotation of the hip. The gluteus medius and minimus both lie deep to the gluteus maximus and arise from the lateral part of the pelvis. The two muscles cross the hip joint, attaching to a bony prominence on the femur called the greater trochanter. Both muscles function to abduct and internally rotate the hip. The deep rotators are a collection of six small muscles (piriformis, gemellus superior, gemellus inferior, obturator externus, obturator internus, and quadratus femoris) that combine to rotate the hip externally and, like the rotator cuff at the shoulder, stabilize the hip joint.
Figure 7.2 Muscles of the back of the legs.
The posterior group is composed of the three hamstring muscles. The biceps femoris, as the name implies, has two heads, one arising from a part of the pelvis called the ischial tuberosity and the other arising from the lower posterior aspect of the femur. The two heads combine to form a common tendon that inserts on the head of the fibula. The other two hamstring muscles, the semitendinosus and semimembranosus, also originate from the ischial tuberosity but run along the medial aspect of the knee joint to attach at the medial surface of the superior part of the tibia. Collectively, the muscles extend the hip and flex the knee.
The muscles of the lower leg can be grouped according to their actions at the ankle joint. The gastrocnemius and soleus are the primary plantarflexors and share an insertion into the Achilles tendon. The tibialis anterior and posterior, named according to their attachment location on the tibia, function to invert the foot. The fibularis muscle group (fibularis tertius, fibularis brevis, and fibularis longus), located on the lateral aspect of the ankle joint, originates from the fibula and has the primary function of foot eversion.
For discussion purposes, the muscle recruitment patterns of the freestyle and backstroke flutter kick are described jointly because the patterns are practically identical. The propulsive portion of the flutter kick begins with the torso and core-stabilizing musculature acting as the foundation on which your legs generate their force. The actual kicking movements begin with the hips in a small amount of extension. From this extended position the iliopsoas and rectus femoris are activated to initiate hip flexion. Also acting on the knee joint, the rectus femoris initiates knee extension and is quickly joined by the remainder of the quadriceps group, which helps to increase the force produced during the kick. These muscles remain active throughout the entire propulsive phase of the kick. At the ankle joint, the tibialis anterior and tibialis posterior work in concert to maintain the foot in a position of slight inversion, while contraction of the gastrocnemius and soleus plantarflexes the foot. The hip extension that takes place during the recovery phase is guided by the hamstrings and gluteus maximus. Unlike in flutter kicking, during butterfly and dolphin kicking the torso serves not only as the foundation for the kick but also as a component. The undulating body movements of the torso initiate the kick, and paired movements of the legs follow in a manner identical to the action of the flutter kick. One difference in the paired movement of the legs is that a greater amount of flexion and extension occurs at both the hips and knees. The undulating movement of the torso is guided by the contraction of the abdominal and erector spinae muscles, but the muscles that guide the movements of the legs are identical to those used in the flutter kick.
The starting point for the propulsive phase of the breaststroke kick is with the feet 8 to 10 inches (20 to 25 cm) apart and the knees and hips flexed. From this position the TFL, gluteus medius, and gluteus minimus internally rotate and abduct the hips, which results in the legs further separating from each other. As the ankles begin to separate, the biceps femoris contracts, pulling on the outer portion of the lower leg, which externally rotates the lower leg and results in further separation of the ankles. At the same time the fibularis muscle group contracts to evert the foot. These combined movements place the legs in the position to begin the whip portion of the kick. From this position the gluteus maximus contracts forcefully to extend the hip, the quadriceps muscle group functions to extend the knee, and the powerful adductor muscles (adductor magnus, adductor longus, adductor brevis, pectineus, and gracilis) pull both legs back toward the midline of the body. At the ankle joint the tibialis posterior, gastrocnemius, and soleus contract to return the ankle to a streamlined plantarflexed position for the glide portion of the stroke. Recovery is accomplished by recruitment of the rectus femoris and iliopsoas, which serve to flex the hip, and recruitment of the hamstrings,
which serve to flex the knee.
Back Squat
Execution
1. Rest the barbell across your upper back and position your feet shoulder-width apart.
2. Initiating the movement with your hips, squat down until your thighs are parallel to the ground.
3. Return to the starting position by straightening your legs.
Muscles Involved
Primary:Rectus femoris, vastus medialis, vastus intermedius, vastus lateralis, gluteus maximus, gluteus medius
Secondary:Erector spinae, biceps femoris, semitendinosus, semimembranosus, adductor magnus, adductor longus, adductor brevis, pectineus, sartorius, gracilis, transversus abdominis, external oblique, internal oblique
SAFETY TIP
Improper squat technique is one of the leading causes of injuries during dryland or weight-room training. Be sure to start with a light weight and add weight only when you have become comfortable with performing the lift and have had a certified strength and conditioning professional review your technique.
Swimming Focus
Squats are a good all-around exercise because they recruit all major muscles groups of the lower extremity. Increasing the strength of the knee extensors transfers to improved force generation and endurance when kicking, regardless of stroke. Strengthening of the gluteal muscles, specifically the gluteus maximus, helps to improve the force that is generated with the extension of the hip during the breaststroke kick. Because of the similarities in the movements performed in squats and starts, particularly flat starts, squats should be a mainstay exercise for enhancing a swimmer’s start.
Extra caution should be used because of the potential for injury to the low back or knees. To protect the low back, beginners should start with just the bar until they are fully comfortable with the exercise. Emphasizing tightening of the core musculature, as described in the introduction to chapter 5, will also help protect the low back. The most common causes for injury to the knee are shifting of the knees forward past the toes or allowing the knees to collapse inward when squatting down.
VARIATION
Overhead Squat
Advantages of overhead squats are that they place a focus on maintaining an upright body posture and develop strength and confidence with the arms in an overhead position. Weight used is much less than in a traditional squat, so starting this exercise with a wooden dowel is best.
Single-Leg Squat
Execution
1. With a dumbbell in each hand, stand 2 feet (60 cm) in front of a flat bench and position your feet hip-width apart.
2. Reach back with one foot and rest your toes on the bench.
3. Initiating the movement with your hips, lower your body until the thigh of the standing leg is near parallel to the ground.
4. Return to the starting position by straightening your leg.
Muscles Involved
Primary:Rectus femoris, vastus medialis, vastus intermedius, vastus lateralis, gluteus maximus, gluteus medius
Secondary:Erector spinae, biceps femoris, semitendinosus, semimembranosus, adductor magnus, adductor longus, adductor brevis, pectineus, sartorius, gracilis, transversus abdominis, external oblique, internal oblique
Swimming Focus
Like double-leg squats, single-leg squats target all the major muscle groups of the lower extremity. An advantage of single-leg squats is that they isolate one leg at a time, which can help address muscle imbalances that may exist between the legs. Targeting all the major muscle groups of the lower extremity improves kicking strength and endurance as well as strength with starts and turns.
During the exercise, you should use the back leg for balance purposes only. As your confidence and balance improve, you can substitute a physioball for a bench. Give extra attention to the positioning of your knee as you lower into the squatting position. Repeated inward dropping of the knee and forward translation past the toes are technique flaws. If you notice these flaws, modify either the weight or number of repetitions to reduce the intensity of the exercise.
Dumbbell Step-Up
Execution
1. Holding a dumbbell in each hand, stand facing a box.
2. Step up onto the box with one leg. Pressing through this leg, lift yourself upward until both feet are on the box.
3. Step down with the leg that initiated the exercise.
4. Repeat, initiating the exercise with the opposite leg.
SAFETY TIP
To protect the low back, you must maintain a tall, upright posture during the entire exercise. A common technique flaw is leaning the upper trunk forward.
Muscles Involved
Primary:Rectus femoris, vastus medialis, vastus intermedius, vastus lateralis, psoas major, gluteus maximus, gluteus medius
Secondary:Biceps femoris, semitendinosus, semimembranosus, adductor magnus, adductor longus, adductor brevis, pectineus, sartorius, gracilis, gastrocnemius, soleus, transversus abdominis, external oblique, internal oblique
Swimming Focus
Dumbbell step-ups are another good exercise for targeting all the major muscle groups of the lower extremity at the same time. Strength gains will carry over to improved strength and distance off the starting blocks, especially with track starts because of the single-leg isolation, as well as turn walls. Targeting of the knee extensors will transfer to force development and stamina with kicking.
To maximize the benefit of the exercise, emphasize a slow, controlled descent from the top of the box. The difficulty of the exercise can be modified by altering the height of the box.
VARIATION
Barbell Step-Up
As your strength improves, using dumbbells may become impractical, at which time you can implement the use of a barbell. When using a barbell, rest it on the trapezius as if you were performing a barbell squat, but be aware that the weight will shift farther from the center of gravity compared with using dumbbells. Be ready for a change in balance.
Lunge
Execution
1. Rest the barbell across your upper back and position your feet shoulder-width apart.
2. Step forward, bending the knee of your front leg until your thigh is parallel to the ground. Avoid allowing the back knee to touch the ground.
3. Push back with the front foot to return to the starting position.
Muscles Involved
Primary:Rectus femoris, vastus medialis, vastus intermedius, vastus lateralis, gluteus maximus, gluteus medius
Secondary:Erector spinae, biceps femoris, semitendinosus, semimembranosus, adductor magnus, adductor longus, adductor brevis, pectineus, sartorius, gracilis, gastrocnemius, soleus, transversus abdominis, external oblique, internal oblique
Swimming Focus
This exercise engages all the major muscle groups of the lower extremity in a dynamic fashion that incorporates a balance component. Use of this exercise will lead to improved kicking performance and have a beneficial effect on starts and turns.
To avoid leaning your torso forward during the exercise, in the starting position pick an object at eye level and maintain focus on that object throughout the entire lunge. By using this technique your head will stay up, and subsequently your torso will remain upright. Pay close attention to the position of your knee in relation to your foot. In the ending position your lower leg should be perpendicular to the ground.
VARIATIONS
Walking Lunge
To perform this variation, instead of pushing back, shift your weight forward. Push off your front leg and bring your back leg to the forward position, recreating the lunge position.
Diagonal and Lateral Lunge
The diagonal and lateral movements increase the demands placed on the adductor muscle group, which will be of extra benefit to breaststrokers. To mix up a dryland program, try replacing forward lunges with a repeating cycle of a forward lunge followed by a diagonal lunge and then a lateral lunge.
Diagonal lunge.
Lateral lunge.
Standing Hip Internal Rotation
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Execution
1. Standing on one leg, reach with your arms and trunk to the inner side of the weight-bearing foot.
2. Use the weight-bearing leg as a pivot point.
3. Reach your arms and trunk toward a point on the ceiling above and slightly behind the same shoulder.
4. Hold the free leg in a flexed position and simultaneously rotate it with the trunk, driving the knee upward toward the ceiling with the arms.
Muscles Involved
Primary:Tensor fasciae latae, gluteus medius, gluteus minimus
Secondary:None
Swimming Focus
This exercise targets a select group of muscles that are responsible for internal rotation of the hips, a movement that is primarily seen in swimming during the recovery phase of the breaststroke kick as the heels are brought toward the buttocks. Breaststrokers will therefore benefit most from the exercise. But other swimmers should not ignore the exercise, because a small rotational component takes place during the other strokes. Like the rotator cuff muscles of the shoulder, these muscles play a protective role and help stabilize the hip joint. This exercise is also useful for teaching balance and postural control, especially for younger swimmers.