Saturday, 11 June 2016

Cycling Exercise Part 1: Muscle Form and Function in Cycling

This is a resume from book "Cycling Anatomy" written by Shannon Sovndal. The book explain what muscle worked when you cycling and how to increase the flexibility and strenght with proper training.

Since its in English and had many biological terms, i suggest you to read this article with a cup of coffee and plenty of free time. :)


The Cyclist in Motion

In cycling, as in any other athletic endeavor, the athlete’s body must have a strong, solid base. This is the key to reaching top performance, avoiding injury, and achieving longevity in the sport.

Many cyclists fall into the trap of thinking that cycling is all about the legs. Unfortunately, it is not that simple. Your legs, hips, and buttocks do generate the majority of your cycling power, but to stabilize the lower half of your body, you need to have a strong abdomen, back, and upper body.

Cycling is a full-body activity. This will become clear as you read the anatomic description of the cyclist in motion. Each area of the body plays a vital role in distributing your power to the pedals, controlling your bicycle, and preventing injury.

If you lack training in a particular area of your body, the entire system falls out of alignment. This will not only cause a degradation in performance, but may also result in pain or injury.

Muscle Form and Function in Cycling

To help you understand why weight training improves performance, let’s begin with a brief explanation of muscle physiology. Once you understand how a muscle works, you’ll also understand the optimal muscle position and, hence, the importance of proper form during your exercises.

The fundamental functional unit of the skeletal muscle is called the motor unit. It is composed of a single motor nerve (neuron) and all the muscle fibers it innervates. Each muscle fiber breaks down into numerous rope like myofibrils that are bundled together (see figure 1.1).

figure 1.1
By activating more or fewer motor units, the muscle generates a gradation of tension. Graded muscle activity refers to this variable tension generation. The frequency at which the nerve activates the motor unit also contributes to muscle tension. The most notable example of this is tetanus, which occurs when the nerve fires so fast that there is no time for relaxation of the muscle.

Composed of actin filaments and myosin filaments, muscle fibers work like a ratchet system. Figure 1.2 shows the functional structure of a muscle. The action of a muscle fiber can be compared to a rock climber on a rope.

fig 1.2
In this analogy, the rope represents muscle actin, and the climber represents muscle myosin. Just as a climber pulls himself up with his arms, the myosin pulls itself along the actin.

Imagine the climber clinging to a rope. To move upward, he locks his legs, outstretches his arms, and pulls. Repeatedly, myosin climbs the actin. As the myosin moves along, the muscle fiber shortens, or contracts. This creates tension and allows the muscle to perform work.

Each muscle has an optimal resting length. This optimal length represents the perfect compromise between having a large number of cross-linked actin and myosin while still leaving enough “spare rope” for the myosin to climb up. Overstretching or understretching wastes the full energy potential of the muscle.

Figure 1.3 shows proper cycling position on a road bike. Note that there are five points of contact with the bicycle (legs, buttocks, and arms). In addition, most major muscle groups will be engaged during the cycling motion. If you need help properly fitting your bicycle, you can find information in Fitness Cycling (Human Kinetics, 2006). You can also have a professional bike fit done.

fig 1.3
Because the cranks on a bike extend 180 degrees in opposite directions, one of the cyclist’s legs will be extended when the other leg is flexed. This allows the flexor muscles on one leg to work at the same time that extensors are firing on the opposite side.

With each rhythmic turn of the crank, the legs will cycle through all the various muscle groups. In proper form, you should have only a slight bend at the knee when your leg is in the 6 o’clock position. This stretches the hamstring to the ideal length and prepares for optimal firing during the upward pedal stroke.

At the same time, the opposite pedal is at the 12 o’clock position, causing your thigh to be nearly parallel with the ground. This optimizes the gluteus maximus for maximal power output during the downward stroke and the quadriceps for a strong kick as your foot rounds the top of your pedaling motion.

As you rotate through the pedal stroke, your ankle will allow your foot to smoothly transition from the knee-flexed position to the knee extended position. Just as the flexors and extensors of your upper leg alternate as they travel in the pedaling circle, your calf and lower leg muscles will add to the power curve during most of the pedalingmotion. The calf and lower leg muscles will also help stabilize the ankle and foot.Proper seat height plays a key role in establishing this proper muscle position.

Because of the basic bent-over position of the rider on a bike, a strong and healthy back is crucial to cycling performance and enjoyment. That doesn’t mean you shouldn’t ride if you’ve ever had back problems. Rather, it means that you’ll need to strengthen and care for your back if you want to have a long cycling career. The erector spinae, latissimus dorsi, and trapezius muscles support the spine as you lean forward on the bike.

Riding also stresses your neck. Both the splenius and the trapezius help keep your eyes on the road by extending your neck. Again, because of the strain on all these muscles, proper conditioning of your back is a necessity for healthy and pain-free riding.

The rectus abdominis, transversus abdominis, and abdominal obliques (internal and external) provide anterior and lateral support to the torso, countering the well-developed muscles of the back. If either the back, anterior, or lateral muscles are weak compared to the others, you’ll experience poor spinal alignment, unnecessary spinal stress, and pain. Back pain may have nothing to do with malfunctioning or weak back muscles. It may, in fact, be caused by a lack of conditioning of the abdominal muscles.

Your arms contact the bike for both control and power delivery. While you are holding the handlebars, each arm should maintain a slight bend at the elbow. As you pedal, the flexors and extensors in your arm will alternate from contraction to relaxation. The biceps, triceps, and forearm muscles all work in unison to stabilize your torso via the shoulder joint.

Because of your riding position, your shoulder is constantly under pressure. Numerous muscle groups-including the rhomboid, rotator cuff, and deltoid-help maintain proper stability and position. Your chest muscles support and balance the musculature of your back and shoulders.The pectoralis major and minor allow you to lean forward on the bike and move the handlebars from side to side while climbing.

The exercises in each chapter will not only improve your strength but will also improve your flexibility. Cycling allows the rider to exercise without unduly stressing the joints. However, this benefit also has a downside.

In any type of training, stress develops strength. Because of the smooth pedaling motion, very little stress occurs at the bone. Athletes who only participate in cycling have an increased risk of osteoporosis. This is another reason why weight training is crucial for avid cyclists. Time spent in the gym will help prevent weak and injuryprone bones. Resistance training enhances bone mineralization, making your bone architecture stronger.

To be continued...

Source: "Cycling Anatomy" by Shannon Sovndal.

Ride On!

No comments: