Summary
The Stretch-shortening cycle (SSC) is based on pre-stretching and resistance principles that occur during typical human movements, such as jumping, walking, running, bending, and extending the arms. Pre-stretching improves performance during exercise and is linked to storing and releasing energy in the tendon. Specific training methods enhance preliminary muscle activity and athletic performance – plyometric and ballistic training. During countermovement jumps (CMJ), the sportsmen jump 2-4 cm higher than during the squat jump (SJ) because the CMJ engages the lowering before the stretch (“Stretch-shortening cycle,” 2021). This pre-stretching is the first element of the stretch-shortening cycle.
SSC consists of those phases – eccentric, shock absorption, and concentric. During SSC, there is a rapid cyclical muscular action: first, the muscle goes through an eccentric contraction, followed by a period of amortization or transition, and the cycle ends with a concentric contraction. SSC can be described in terms of a spring mechanism, where the compression of the spring causes it to rebound at an increased speed. Therefore, an increase in the speed or compression force will cause the spring to jump further and higher. SSC occurs during any movement where the limb changes direction, for example, in team sports.
Three Main Energy Pathways
In almost any sport, athletes use all three major energy pathways. For example, long-distance running or endurance running utilizes all three energy pathways – phosphagen, anaerobic, and aerobic. When athletes start, they use the phosphagen pathway for 30-60 seconds. Further, to achieve a steady state during endurance training, the runner’s body can go to the anaerobic path; this period lasts from 30 to 180 seconds.
Then, the runner’s body chooses the aerobic energy pathway during prolonged exercise to get energy for long periods. During the run, the athlete’s body can alternate methods of obtaining energy, depending on the body’s needs at a particular moment. The utilization of all three pathways is necessary for the runner to compete because each pathway provides energy for the different phases of the run – the phosphagen pathway ensures start, the anaerobic pathway helps the athlete to achieve steady-state running, and the aerobic pathway allows them to endure the prolonged exercise.
Energy pathways are how the body receives energy from the system of activating various chemical functions. The body gets energy from food, but that food needs to be converted to adenosine triphosphate (ATP). ATP is a form of chemical energy used for all cell functions. The body stores only a minimal supply of ATP in the muscles, synthesizing it from food, and converting proteins, fats, and carbohydrates into glucose, fatty acids, and amino acids. Once broken down, these substances are transported through the blood or stored for the future. ATP synthesis occurs using one of the energy systems – phosphagen, anaerobic, and aerobic.
The phosphagen system uses creatine phosphate by directly breaking down ATP to release energy. Creatine phosphate and ATP are present in small amounts in the body but are instantly available and used at the start of the activity and for short-term high-intensity exercise. Anaerobic glycolysis does not require oxygen and uses the resources in glucose to form ATP. This path is used for activities that require large bursts of energy of a longer duration. Aerobic glycolysis requires oxygen, burning fats and carbohydrates to produce ATP. This energy pathway is used for sustained energy production during prolonged, low-intensity exercise. The body goes into the aerobic pathway after the phosphagen and anaerobic systems are tired.
Plyometric Exercise
Plyometric is a form of intense exercise that uses the SSC principle. These workouts help athletes improve overall and explosive strength by training muscles for strength and speed. Plyometric exercise is a sequence of movements that involves stretching a muscle followed by an immediate contraction of the same muscle. These exercises are also called jump training and aim to improve explosive strength, that is, the ability to generate maximum strength in a minimum amount of time. Start sprinters and long jumpers use explosive force, which is expressed in the form of a high-energy and fast body push through space.
Examples of plyometric exercises include vertical jumps, long jumps, single-legged jumps, and clap push-ups. For exercise, athletes often use special metal platforms that allow jumping and descending, creating dynamics. Plyometric exercises place increased stress on tendons, ligaments, and joints and have an increased risk of injury, so they must be performed strictly in their traditional form. When performing, one needs to gradually increase the exercises’ duration, intensity, and complexity.
Exercises for the upper body include clap dips; this exercise starts from a plank position. Then the athlete needs to do regular push-ups, dropping to the floor, and when pushing up, push off hard enough and raise body and arms above the ground as high as possible. After that, the athlete needs to clap their hands and return to the starting position; the exercise must be repeated for 30 seconds. Lower-body plyometric exercises include leg exercises like squat jumping. The athlete should stand with their legs spread wider than their hips and squat, lowering the body. At the bottom, they need to straighten their feet, use their abdominals, and jump. During the jump, the athlete must raise their arms above their head and after landing, lower themselves back to a squatting position.
Test for Assessing the Explosive Strength
Explosive strength or power is an important indicator of training success. The broad jump is the most effective test to determine the athlete’s ability in this direction, as it requires demonstrating the elements of strength and speed. The athletes must perform tests to understand their body’s condition. To make a long jump, the athlete must stand on the line without stepping into it with their toes, choose a space in front and jump to it, and quickly bend their arms back when jumping. The secret is to make an energetic movement with arms, imagining that the bouncer is throwing a handful of pebbles from their hands on the ground with all their might. A positive result or test goal is to jump six to eight feet, measured to the point of landing of the heels.
SMR and Stretching
Self-myofascial release and stretching is a type of exercise using an external source of tension. For example, athletes can use a foam roller to pressure tendon organs to suppress muscle spindle activity. If an athlete has a problem due to an overactive muscle, they stretch the area of tension by applying a roller to the affected muscle. Examples of muscles that are prone to hyperactivity are hamstrings, glutes ad piriformis, latissimus dorsi and tricep, pectoralis group, upper trapezius, posterior glenohumeral, and hips.
SMR exercise for hamstrings is essential as these muscles are the largest and affect all movement while standing. For exercise, a high-density foam roller is used; SMR will help improve flexibility, flexion, and general movement. To start the exercise, an athlete needs to sit down with the back of their thighs on the roller and put both hands on the floor behind. It is necessary to scroll the hamstrings from just above the knees to just below the pelvis.
To increase the intensity, an athlete can shift the weight to one leg. A standard foam roller is used for SMR exercises for glutes and piriformis. The athlete sits on the roller, crossing an ankle over the opposite knee, and placing hands behind their body. The exercise is performed by slowly swinging back and forth on the buttock of the bent leg, and then the position of the legs needs to be changed.
To start the SMR exercise for latissimus dorsi and tricep, an athlete needs to lie on their side on the floor, stretch their arm over the roller, placing it in the armpit pressed against the latissimus muscle. The athlete should swing gently in all directions, keeping the body in areas of tension as long as pain can be tolerated. To start the SMR exercise for the pectoralis group, one needs to use a 36-inch roller and lie on it, resting on it with the entire spine from head to hips. For balance, the athlete should place their arms to the sides, bend their legs and leave their feet on the ground. The athlete should swing the whole body from side to side, not twisting the spine, but pumping the body like a log; the head moves in the opposite direction.
For the upper trapezius stretch, the athlete can use the cane to control the force by pressing on the overactive areas and holding pressure. Pectoralis major/minor stretch includes wall stretch, elbow wrap stretch, backbend stretch, lying chest stretch, standing chest expansion, and stability ball chest stretch. Posterior glenohumeral stretching includes forwarding flexion in the seating position, forward flexion in the supine position, and external rotation. To begin the hip flexor stretch exercise, the athlete should take a lying position, resting their hips on the roller, and supporting themselves with elbows and forearms, and slowly rolling back and forth on a roller just above the knees and just below the hips.
Reference
Stretch-shortening cycle. (2021). Science for Sport. Web.