Knees: Care and Maintenance

1.5.2 Exercice d'application .... les réactions à des actions non définies (vous
décider de faire vos exercices de gymnastique .... Objectif du scénario :
Installation de votre four dans votre cuisine ..... du titulaire du marché de
production ou de TMA (Maintenance réalisée par une entreprise qui n'est ......
résistance aux pannes.

Part of the document


Stand and Deliver
Knees are critical joints, and they can't be traded in like last year's
cell phone. Keep your hinges state-of-the-art with our complete guide to
strength, conditioning, and injury prevention. By Nick Heil | |
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Thank Australopithecus for standing upright more than three million years
ago and making possible such great human achievements as the four-minute
mile, the 360 dunk, and the Eddie Van Halen guitar solo. Of course, A-Man
also sentenced our knees to an eternity of trouble: clicks, creaks, tweaks,
tears, and pops that can make bipedalism look downright backwards.
Considering all that this joint does for us, it's no surprise that knee
problems-some 9.5 million annually in the U.S.-are the leading reason
people see orthopedic specialists. That said, there are ways to avoid
visiting the doc. Follow our guide to proper care and maintenance,
including training and rehab secrets of the pros, and you'll stay in the
game longer and stronger. Your knees have evolved nicely over the eons;
it's high time the care you give them catches up. Axis of Evil
Even if you avoid traumatic injury, these three forces are conspiring
against your knees 1. AGE
As you grow older, circulation and muscles both tend to get weaker. In your
joints, lubricating synovial fluid decreases and dries up. Soft tissue
becomes less elastic and more susceptible to micro-tears; cartilage gets
brittle and begins to flake away. The meniscuses degenerate and lack the
capacity to rebuild-a problem exacerbated by weight gain, which increases
joint stress. As early as your teens, deterioration of your articular
cartilage-a precursor of osteoarthritis-can set in.
2. BIOMECHANICS
Bowed legs, flat feet, pronating ankles, knock-knees, recurring injuries-
any number of things can throw off proper alignment of your joints, and in
time even minor tracking deviations can result in major problems. The
kinetic chain that links your feet to your hips is highly interdependent:
If one part veers off, the entire system can break down.
3. MUSCLE IMBALANCE AND OVERUSE
Simply put, too much of one sport or exercise creates disproportionate
musculature. Cyclists, for example, often develop quads that are far
stronger than corresponding hamstrings. This may be great for hammering
your pals on Saturday morning, but it can leave the knee susceptible to
injury, because underdeveloped muscles can't counter the force of stronger
ones. Devotees of high-impact activities, like running and most ball
sports, also increase their chances of knee problems if they don't mix in
low-impact alternatives such as swimming and cycling.
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Please Your Knees
Now that you know the bad news, you're ready for the good-and there's
plenty of it. You can stack the deck in favor of lifelong healthy knees
with a balanced strength-and-conditioning program, regular flexibility
training, and joint-smart nutrition. The single most important thing you
can do? Give your knees maximum muscular protection. Deliver the goods with
the following exercises.
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Sport-Specific Training: Improve performance and decrease risk of injury by
prepping your knees for mogul fields, marathons, and other targeted
activities. Wendy McClure, personal trainer and co-owner of Body Dynamics
in Boulder, Colorado, advises pro clients to incorporate these exercises
into workouts three times per week, starting two months prior to the
season. To increase difficulty, hold weights for more resistance and place
a pillow underfoot to create instability.
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Cycling > Split Squats
Stand with one foot forward, one back, a few feet between them and your
hips square. Lower until your back knee almost touches the floor, then
rise. Continue 30 seconds, then switch stance and repeat.
Skiing > Sideways Squats
Stand sideways a few feet from a wall and lean toward the wall, bracing
yourself with your hand. Your unweighted inside leg is bent. Lower into a
squat on the outside leg, then rise. Do two 30-second sets. Switch sides
and repeat.
Hiking > Partial Step-Throughs
On a narrow step deck or platform, step up on your right leg, and bring the
left up and through as if you're going to step down to the other side, but
dip down only about 15 degrees, then move back to the start position. You
should be balanced on the same leg throughout the movement. Repeat for 30
seconds on each leg.
Running > Paper-Plate Half Circles
Set a paper plate on the floor one stride length behind you. Balance on
your left leg while extending your right foot back so your toes are lightly
resting on the plate. Sink into a semi-squat position on your left leg. Now
trace a full half circle with your right leg (don't let your knee dip
inward), sliding the plate along the floor until it's in front of you.
Slide plate straight back. Repeat 30 seconds on each leg.
Negatives and Plyometrics: Conventional weight-lifting programs strengthen
muscles as they contract. Problem is, real-world sports often demand that
your muscles lengthen under load. It's called an eccentric action, and it's
what happens when you control your descent while hiking, running, or
skiing. Work this braking action with negatives and plyos, which rely on
resistance rather than lifting. For the following exercises, focus on
excellent form and slow, natural rhythm.
Drop Jumps
On a box, step, or platform (start small), step up and drop to the floor,
lowering into a squat, then spring straight up. Four sets of six to ten.
Advanced: Hold a medicine ball over your head.
Front Squats
Hold an unweighted squat bar at the top of your chest. Lower into a squat
on a ten-count pace, then explode up. Three sets of four to six. Advanced:
Add 10 to 20 pounds.
Single-Leg Hops
On a level stretch of grass or track, leap forward from one foot to the
other for approximately 20 yards. With each landing, hold yourself still,
balanced on one leg, for five seconds. Do four sets. Advanced: Jump at a
slight angle, alternating sides, and touch the ground with your outside
hand on each landing.
Downhill Repeats
Fill a pack with weight (start light and increase gradually). On a sloping
trail, hillside, or stadium steps, hike to the top and descend in small
bounds. Keep your knees bent slightly, so they absorb impact like shocks
during the descent. Do four to six reps of 50 yards. Advanced: Add weight
and do reps of 100 yards.
MIX AND MATCH
You know cross-training is smart, but do you know how to choose a
complementary combination of high- and low-impact activities? Use this
guide to get the most out of multisport.
Sport: Running
Complement: Swimming with fins
Payoff: Adds low-impact balance to your routine. Fins help isolate quads
and hamstrings to build leg strength.
Sport: Skiing
Complement: In-line skating
Payoff: Lateral movement mimics skiing motion, so you build hip strength
and muscle endurance.
Sport: Cycling
Complement: Running
Payoff: The higher-impact activity helps promote bone density, build leg
strength, and keep your weight down.
Sport: Mountain climbing & hiking
Complement: Mountain biking
Payoff: Pedaling up steep, technical trails develops leg and core strength.
And descending? Well, some things are just for fun.
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|Care and Maintenance |
|Strength is just the start. Now add a |
|healthy diet, proper form, and regular |
|stretching. |
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FEED YOUR KNEES
Your joints, like the rest of your body, need plenty of fruits and
vegetables. Even recreational athletes require a minimum of five servings
of each per day. It's the only way to get the micronutrients-vitamins and
minerals-you won't get from other food. "Your body needs calcium,
magnesium, zinc, and vitamin C to heal injuries," says Dr. William Sterett,
of Vail, Colorado's Steadman Hawkins Clinic, a top orthopedic center.
"Multivitamins can help, but nothing delivers nutrients as well as fresh
foods." Joints also benefit from essential oils: Add oily fish (or omega-3
supplements), olive oil, avocados, and almonds to your meals a few times a
week.
|GET AN ALIGNMENT |
|Check your musculoskeletal symmetry with this simple test. Stand on|
|a step, facing down. Put one foot forward, so you're supported on |
|one leg. Dip down until your supporting knee is |
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bent about 30 degrees, then stand back up. Watch your weight-bearing knee:
If it deviates from a straight path (don't panic, most do), you could have
alignment issues. Correction may require expert help-from an orthopedist or
experienced trainer-but the following easy fixes often solve minor
problems.
1.> Shoe Inserts Creating a stable, neutral platform under your foot is
step one, and an over-the-counter insole is an inexpensive, effective way
for most people to get the necessary support. Many ski boots have
"cantable" cuffs to accommodate off-center alignment. Have a shop help you;
it's quick and simpl