The main theories behind why muscle forces accelerate the body upwards greater in countermovement jumps in comparison to squat jumps: a brief review
Throughout literature countermovement jumps (CMJ) are seen to be higher in contrast to squat jumps (SJ) (Bobbert et al. 1996; Kubo et al. 1999; Bobbert et al. 2005). However present literature regarding the key potential mechanisms behind why greater muscle forces are seen accelerating the body upwards in CMJ in comparison to SJ is somewhat unclear. A CMJ can be defined as a positioning starting upright, beginning the descending motion in advance of the upward motion in contrast to a SJ where the start position is squatted with no preparatory countermovement (Akl 2013). The higher jump heights seen in CMJ in comparison to SJ are apparent even if at the start of propulsion phase the body configuration is identical (Bobbert et al. 1996). In past literature three main mechanisms have looked to provide an explanation for the greater muscle forces seen in CMJ than the SJ. The first plausible theory is that the muscle stretch in CMJ increases the production of force capability of the contractile machinery (Edman et al. 1978; Ettema et al. 1992; Herzog et al. 2003). Secondly the assumption that the muscle fibres are on the descending limb of their force–length relationship at the start of propulsion in the CMJ and SJ, however in CMJ the stretching of a chain of elastic components, they are not as far past optimum length therefore allowing a greater force over the initial phase of their shortening range, with the stretching of sequences of elastic components, this then causes the storage of elastic energy that is then reutilized in the propulsion phase (Ettema et al. 1992). The final explan...
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...act to vertical force production is not hindered. However this was not seen by Babbert et al. (1996), as movement disintegration was not present in the SJ and toe off location in CMJ and SJ remained the same.
In conclusion, this brief review suggests that the literature is contradictory in the theory that muscle fibres during a CMJ are less beyond optimum length in comparison to SJ, in turn allowing an increased force during the initial part of their shortening, causing the storage of elastic energy that can then be reutilized during the propulsion phase, therefore further research is necessary. However, it does seem that from a biomechanical perspective the active state development during the preparatory countermovement in a CMJ may increase force by the hip extensors and more work during shortening in CMJ and therefore a greater vertical force and jump height.
This experiment was completed in order to compare calf circumference as well as gender, weight, and jump height. If a person has larger calves, then they will likely be capable of reaching a higher vertical height. It can also be shown that if the person is a male, then they will be able to jump higher. A larger calf circumference is more likely to reflect a high vertical jump due to the fact that the fat content of the calves in the experiment was accounted for, therefore a large calf measurement in this experiment means a muscular calf. It is common knowledge that more muscle will result in stronger legs leading to a higher vertical. While it is believed that males are bigger, faster, and stronger, this leads us to believe that they can also jump higher. Males tend to have stronger muscles at nearly all points in life(Burr, 1997). That being said, the aforementioned hypotheses can be expected to be true because males are likely to have larger, and therefore stronger, calves. It can also be expected that males will display a higher vertical jump(Caruso, 2012).
Tae Kwon Do is a Korean, unarmed martial art and is best known for its kicks (Park, 2001). The roundhouse kick is a turning kick and happens to be the most commonly used kick during competition (Lee, 1996). For this reason, the roundhouse kick will be analyzed in reference to sparring competition.
A course in the sociology of sport and physical activity should be part of an undergraduate curriculum in a kinesiology program because social issues that impact sports and athletes are often overlooked within kinesiology program despite playing an important role within sports. Kinesiology programs tend to focus on the impact of sport and importance of sport and physical activity and could use the insight that sociology of sport and physical activity can provide. The more we know about the social issues around sport and physical activity, and how to limit them, the more we can understand sport and how to improve it and the equality within it.
If an individual attempts to lift objects, there would be no feedback on how hard to flex the muscles except from clues the vision can give. Through feedback from proprioception, the brain is able to calculate angles of movement and command limbs to move certain, exact distances (Lee, 2002). Without this sense, humans would be forced to spend a great amount of their conscious energy moving around, or they would not be mobile at all.
Anderson, D. I., & Sidaway, B. (2013) Kicking biomechanics: Importance of balance. Lower Extremity Review Magazine.
In conclusion, the squat is a lift that works many muscles, increase strength in the legs and hips, but is a full body exercise. I will continue to lift as I train for my sports and I am so thankful and lucky to have an amazing weight training program in Portage High School and also an amazing coach that guides me and helps me train for my upcoming sports. Without him it would be different in the weight room and I wouldn’t like it.
Daniel E. Lieberman, Madhusudhan Venkadesan, William A. Werbel, Adam I. Daoud1, Susan Andréa, Irene S. Davis5, Robert Ojiambo Mang’Eni, Yannis Pitsiladis6. Foot strike patterns and collision forces in habituallybarefoot versus shod runners.2010. Nature Journal. Vol 463 . p531-534
The focus of this paper is mechanically and automatically break down the deadlift. It focuses on the four phases of the deadlift (The lift off, pull through, the lockout, and the lowering phase) as well as the muscles involved in lifting and lowering the load. The sole purpose of the deadlift is for health and fitness. It is a core lift that works nearly every muscle in the body. Muscles from the lower and upper extremities will go through a period of flexion and extension when moving through the phases. The deadlift should be performed safely, and with proper form to avoid injury. This paper shows and demonstrates the proper form of the deadlift. There are also a number of forces acting on the load and the athlete. Gravity and external forces will be an active part of lifting the load. Images and tables are provided in the paper to better understand the movements and muscles used when performing the deadlift.
The vertebral column of the body remains stable due to the isometric co-contraction of the erector spinae, rectus abdominus and the e...
This skill involves jumping in the sagittal plane about the transverse axis. It consists of hip, knee, ankle, and shoulder joints. In the preparation phase in propulsion, the subject has flexed knees and hips which will need to be straightened by the strength of their corresponding joints such as the hinge joint at the knee joint. The hip joint is a ball and socket joint that bears the body weight and allows for jumping motion. During th...
A basketball Jump shot also known as a jumper is one of the most important shots in the game. Its purpose is for the player to jump, usually straight up and while in the mid-air attempt to score while arcing the ball in the basket. Jumps shots are known for winning games, especially crucial last second shots such as mine but it’s a skill that a player should be familiar and have knowledge of. Although it seems simple and easy its actually is a very detailed and mechanical aspect to the game which is why I choose to analyze the biomechanics of a basketball jump shot.
Plyometric exercises are exercises that cause a muscle to eccentrically contract and then concentrically contract and are useful for developing power in soccer. It is important that the movements performed in the exerc...
-Second, hip rotation also helps the runner to have a more natural and smoother run and again reduces the energy required to move the runner’s center of mass.
[3] H. S. Milner-Brown, R. B. Stein, and R. Yemm. "The Orderly Recruitment of Human Motor Units during Voluntary Isometric Contractions." The Physiological Society 230th ser. (1973): 359-70. Web. 22 May 2014.
The purpose of the squat is to train the muscles around the knees and hip joints, as well as to develop strength in the lower back, for execution of basic skills required in many sporting events and activities of daily living. Because a strong and stable knee is extremely important to an athlete or patient’s success, an understanding of knee biomechanics while performing the squat is helpful to therapists, trainers, and athletes alike (11). Because most activities of daily living require the coordinated contraction of several muscle groups at once, and squatting (a multi-joint movement) is one of the few strength training exercises that is able to effectively recruit multiple muscle groups in a single movement, squats are considered one of the most functional and efficient weight-bearing exercises whether an individual’s goals are sport specific or are for an increased quality of life