XNB274 Functional Anatomy Assignment Sample

Lower Body Exercise

Table 1 - Back Squat

1. Analyse with supporting literature muscle activation patterns preferably with EMG evidence that support muscle descriptions

2. This section includes substantial element of the report that evaluates how the limbs are moving and what is controlling that movement.

   1. Basic response example – only mention the deltoids as being agonists in a shoulder press.

   2. Detailed well-rounded response – the 2:1 motion of the scapular and the role that supraspinatus has in allowing humeral abduction with supporting literature.

The Back Squat

The back Squat is considered one of the best resistance-based exercises when training for overall strength if performed correctly. We have categorised the muscles into their appropriate categorise based on their contribution and role in the movement (Wirtz et al., 2016). Muscle activation pattern with Electromyography (EMG) evidence are included and supported in this muscle description to show how the limbs are moving and what is controlling that movement. The back squat can be divided into four different motions ‘Top position – Eccentric phase – Bottom position - Concentric phase’ however, this report solely investigates the two main movement such as the eccentric and concentric phases.

Phase 1 – Eccentric Phase

Eccentric or the lowering phase is the very first movement of a squat. The main muscles that are heavy targeted also known as the agonist muscles are the quadriceps (all four muscles) and the gluteus maximus. Both muscle groups are working together to extend the leg therefore achieving the knee flexion. On the descent, the knee and hip angles starts to shorten while the back angle becomes more horizontal as the squat gets deeper into range of motion. Due to the flexing of the knee and hip joint, the extensors of these joints get loaded eccentrically as they prepare for hip extension (Wirtz et al., 2016). While the hamstring rotates around the hip joint during the movement, the erector spinae and abdominal muscles does its job by holding the back in a lumbar extension. As the hips pushes back making the back more horizontal, the hamstrings pull and rotates away therefore lengthens.

Although it lengthens, the hamstring muscle crosses the knee joint making it a knee flexor and as the knee flexes it also shortens. Due to the nature of the hamstring shortening and lengthening, it is considered a synergist muscle (table 1) by isometrically contracting to help control the hip joint. As the knees are flexing through the motion, the quadricep muscles that are the knee extensors becomes heavily loaded because its attached to the femur via the patella and quadricep tendons. As the squat reaches the bottom position, the hip drops below parallel to the ground and the hamstring muscles reaches its full stretch potential therefore loading the quadriceps the max force and are ready to generate concentrically.

Phase 2 – Concentric Phase

Just like the eccentric phase, this movement is in reverse direction with a vast load of force on the posterior muscles (hamstrings, erector spinae, gluteus maximus, gastrocnemius) and the quadriceps. To break-through the force of gravity of the barbell that are acting on the hip and knee joints, the erector spinae and abdominals stays contracted and tight while all the muscles must work together in a single upward motion (Vigotsky et al., 2019). The greatest percentage of load of force as we all know are in the hip joint so therefore the hips must fully extend and increase in angle from the bottom position to get up.

The adductors, hamstrings and gluteus maximus basically acts as a bounce or in other word a ‘rebound’ when changing from eccentric to concentric contraction at the most bottommost point. When this happens, the hamstrings are greatly stretched thus becoming a crucial reason the erector spinae remain tight as the hip angle closes before the rebound. This means the hamstring produces the largest portion of the rebound to be able to start opening the hip joint. While the hip extends out, the knee joints also follows during the phase. This is done by the knee extensors, the quadricep muscles at the distal femur and along the tibia contracts to pull the force that crosses the knee joint. At this point, all the posterior muscles as well as the adductors, abdominals, hip flexors and the quadricep muscles have one goal to achieve, to fully extend at both joints and return the body at its starting position safely.

Muscle activation patterns with EMG
There is much inter-subject, inter-muscle and context-dependent variability in the electromyographic ( EMG) activity pattern for individual muscles in the Gaite cycle (Van et al., 2017). Squat helps to strengthen the muscles around the knees and hip joints and create energy into the lower back to exercise the essential skills needed for certain athletic competitions and day-to-day activities. Squat manoeuvre begins in a straight line, with the lifter stretching its knees and hips entirely. The lifter breaks back by stretching the joints of the elbow, knee and ankle. The elevator climbs back to the correct place when the required squat depth is achieved. Throughout squat operation, the lumbar spheres are kept in a balanced orientation and the trunk will stay as straight as practicable during squat.

The athlete 's feet must remain steady and securely placed on the ground and the athlete must hold his foot right over the squat action. The femurs are slightly parallel to the ground at the correct depth, the hips bend, the tibia vertical and the feet completely on the floor. There are several reports evaluating a number of bio-mechanical factors during the Squat cycle to provide athletes and their trainers with knowledge to monitor fitness preparation, success and professional performance (Vigotsky et al., 2019). The EMG surface was widely used for muscle activity evaluation during squat, and EMG activity has been shown to increase by increased loads in various squatting studies.

Bryanton and others have researched bio-mechanical and relative muscular tension during squat, but have not used EMG in the estimation of muscle function and more specifically the overall load predicted to be observed in kinetic and muscular function shifts, thus growing the barbel load from 50 percent to 90 percent. Studies shows that knee and hip joint musculature and cinematics with 80 percent, 90% and 100 percent (1RM) loading during squat (Van et al., 2017). With increased load, the EMG activities for all muscles increased, but only statistically significant differences for VM and GM were observed. For any muscle function detected between 90% and 100% of 1RM, no statistically meaningful distinction occurred. The movement pattern for 100% loading in hip joint movie technology was different.

Upper Body Exercise

Table 2 - Bench Press

The Bench Press is one of the most popular upper body exercises amongst athletes of all levels and everyday gym trainers. In this section of the analysis, muscle activation pattern is shown using an EMG with supporting related evidence (Vigotsky et al., 2019). There are many variations of the bench press including wide and close grip bench press, incline and decline bench press, dumbbell chest press and reverse grip bench press. However, in this analysis it solely focuses on the traditional barbell bench press and its biomechanics along with the overview of it’s eccentric and concentric contraction phase during the exercise.

This exercise is a compound movement incorporating multi joint activities that targets muscles in the upper torso using joint actions such as horizontal shoulder adduction and abduction, and elbow flexion and extension. The prime mover that is recruited during the press is the pectoralis major, the largest muscle in the chest. The anterior deltoids which are in the front of the shoulders, are responsible for lifting the arms concentrically and keeping them forward as the bar moves from the chest back to the starting position.The Bench Press

Phase 1 – Eccentric Phase

The first phase, lower weight toward the chest, is called the eccentric, or muscle-lengthening motion. The second phase, as you raise the weight back up, is called the concentric, or muscle-shortening phase (Strazza et al., 2017). When the upper body muscles are contracting during the eccentric phase, the muscles working elongates due to the lowering of the weight against a controlled resistance. This requires carefully controlled movement from both the shoulder and elbow muscles due to the immense pressure it brings on the joints and to prevent the weights from collapsing into the chest. The eccentric phase of a lift occurs when a muscle contracts while lengthening. This is the down motion of the bench press, biceps curl, or squat. The concentric phase of a lift occurs when a muscle contracts and shortens, as in the up motion of the bench press, biceps curl, or squat.

Phase 2 – Concentric Phase

The concentric phase of a lift occurs when a muscle contracts and shortens, as in the up motion of the bench press, biceps curl, or squat (Schoenfeld et al., 2016). The isometric phase of a lift is when a muscle contracts but no movement occurs, such as during a bench press when supporting the bar at arm's length or resting it on your chest. It is during the concentric phase that the chest is felt getting tight. Learning which muscles are used during the concentric phase of the bench press is beneficial for focusing mind on the correct area and therefore improving the exercise.

Muscle activation patterns with EMG

As the hips and knees bent in the bench, both elevated muscles (p<0.01; d>0.5) had dramatically decreased activation of the muscle. The pectoralis principal showed the highest activation, followed by the deltoid anterior and the brachii triceps. Electromyography (EMG) is a diagnostic method used in the evaluation of the health of motor neurons' muscles and nerve cells. Engine neurons transmit electrical signals that contract muscles (Micke et al., 2018). Higher EMG exercises offer greater muscle strength gains over a workout. In fact, although several variables affect the percentage of maximum activity, an EMG activation level of 60% is considered to induce muscle strength and structural strength. High resistance training leads to relatively high levels of muscle activity that induce muscle strength growth and can improve athletic performance, musculoskeletal health and body aesthetics during a training period adjustment. During bench press.adaptation, the electromyography signal carries valuable muscle data.

The graph reveals that five static contractions for the Triceps Brachii were reported in a raw surface. If the muscle is calm, electromyography ( EMG) may be used more or less without noise. The raw data indicates that Triceps Brachii activation is higher during Bench Press at five repetition limit (5RM) levels (García-Ramos et al., 2020). Two muscles such as Triceps Brachii are activated during the bench press exercise. MAV and Direct evidence for muscle stimulation recognition. During bench press exercise, Triceps Brachii activation is higher.

Single Joint Exercise

Table 3 - Leg Extension

The quadriceps are only feasible with single joint movements like leg extension. In the most common guidelines for muscle development, 8-10 routines of single or multi-joint movements will be used in weight lifting (Jammes et al., 2017). Leg extensions represent a crucial exercise for strengthening the knee patellar ligament and quadriceps. It is also a successful finishing exercise because it is a quadriceps isolation workout, and can be completed after hybrid workouts, including squatting or dead lifts. You can concentrate more selectively on target muscles. Although the elbows, thighs, and hips do bend and flex throughout the workouts, the main movement is the whole body, which follows the frontal plane side-to-side. The knees are similar to an external disk, and is able to divide the body into left and right sections, by flexing and stretching the lower extremity as well. Therefore, the hips shift back and forth, while maintaining the direction of the sagittal axis.

Leg Extension

Phase 1 – Eccentric Phase

If a muscle speeds down under pressure, it is an excentritic contraction. This tends to compress but is getting longer to lower the body at the same time. When you stand up, you stretch or lift your knees. You focus your quadriceps and hamstrings to sustain yourself and conclude the repetition. The leg extension of Quadriceps is antagonistic (Calatayud et al., 2018).

The quadriceps and hamstrings contract excentrically. If a muscle lengthens under pressure, an excentricious contraction is present. This tends to compress but is getting longer to lower the body at the same time. You should push or straighten out the knees. The key muscles involved in leg stretches are the quadriceps. The quadricepes are found on the thighs bottom, like the internal vast body , called the quadric muscles, the external vastus lateralis, the flaring quadric muscles, the intermediate vastus vastus deep in the center and the femoris superficial center.

The four muscles stretch the lower leg and move it slightly inward (de Hoyo et al., 2016). The femoral rectum also acts to stretch the legs, like sitting on a position. When the legs are straight, you will relax the knees and go back to the top. The quads contract excentrically at this stage and thus prolong the cycle. However, during the eccentric stage the lower legs move internally such that the feet are pointed inland rather than correct hands.

Phase 2 – Concentric Phase

Leg extension involves straightening your beet against resistance while sitting in a bent-knee position. The first step, knee expansion, is focused action, also known as muscle minimizing activity. In operating the leg extension system, the quadriceps muscles are activated. The rectus femoris, vastus lateralis, vastus media and vast intermedius are the muscles of these sections. The rectal femoris is the most exercised organ during this workout. Leg extensions involve lifting the leg over opposition while you are sitting from a bent-knee posture.

The first step, the expansion of the leg, is intense motion, also known as muscle shortening. The four quad muscles contract and straighten the lower leg during this process. When the leg rotates slightly externally, these same muscles also point the feet slightly externally.

Muscle activation patterns with EMG

Lower limb muscle activation levels during this procedure and its differences provide very little evidence of the LP workout. Mechanical shifts influence the function of the lower limb of the muscle and contribute to the load. Rectal femoris and gastrocnemius are more involved in the LP45 and LPL at high stress rates than in the LPH (Bélaise et al., 2018). The rectum femoris and large laterals (quadriceps) are more involved during the LPL than during the LPH at a high degree of effort. Once again, LP45 and the LPL have more operation than LPH in rectus femoris and gastrocnemius.

The maximum activity of the gluteus during the LPH is on the other hand greater than that of the LPL. If LP differences exist at high or intermediate intensity thresholds regardless of the technical variables and the numerous loads that emerge during multiple LP activities, muscle movement trends become specific. The LPL should be done if the objective is to induce greater femoral rectus and large lateral (quadriceps). In comparison, LPH should be practiced if the goal is to trigger maximal gluteus operation.

References

Bélaise, C., Dal Maso, F., Michaud, B., Mombaur, K., & Begon, M. (2018). An EMG-marker tracking optimisation method for estimating muscle forces. Multibody System Dynamics, 42(2), 119-143.

cMethodological choices in muscle synergy analysis impact differentiation of physiological characteristics following stroke. Frontiers in computational neuroscience, 11, 78.

Calatayud, J., Vinstrup, J., Jakobsen, M. D., Sundstrup, E., Colado, J. C., & Andersen, L. L. (2018). Influence of different attentional focus on EMG amplitude and contraction duration during the bench press at different speeds. Journal of sports sciences, 36(10), 1162-1166.

de Hoyo, M., Gonzalo-Skok, O., Sañudo, B., Carrascal, C., Plaza-Armas, J. R., Camacho-Candil, F., & Otero-Esquina, C. (2016). Comparative effects of in-season full-back squat, resisted sprint training, and plyometric training on explosive performance in U-19 elite soccer players. The Journal of Strength & Conditioning Research, 30(2), 368-377.

García-Ramos, A., González-Hernández, J. M., Baños-Pelegrín, E., Castaño-Zambudio, A., Capelo-Ramírez, F., Boullosa, D., ... & Jiménez-Reyes, P. (2020). Mechanical and metabolic responses to traditional and cluster set configurations in the bench press exercise. The Journal of Strength & Conditioning Research, 34(3), 663-670.

Jammes, Y., Behr, M., Weber, J. P., & Berdah, S. (2017). Consequences of simulated car driving at constant high speed on the sensorimotor control of leg muscles and the braking response. Clinical physiology and functional imaging, 37(6), 767-775.

Micke, F., Kleinöder, H., Dörmann, U., Wirtz, N., & Donath, L. (2018). Effects of an eight-week superimposed submaximal dynamic whole-body electromyostimulation training on strength and power parameters of the leg muscles: a randomized controlled intervention study. Frontiers in physiology, 9, 1719.

Schoenfeld, B. J., Contreras, B., Vigotsky, A. D., Ogborn, D., Fontana, F., & Tiryaki-Sonmez, G. (2016). Upper body muscle activation during low-versus high-load resistance exercise in the bench press. Isokinetics and Exercise Science, 24(3), 217-224.

Strazza, A., Mengarelli, A., Fioretti, S., Burattini, L., Agostini, V., Knaflitz, M., & Di Nardo, F. (2017). Surface-EMG analysis for the quantification of thigh muscle dynamic co-contractions during normal gait. Gait & posture, 51, 228-233.

Vigotsky, A. D., Bryanton, M. A., Nuckols, G., Beardsley, C., Contreras, B., Evans, J., & Schoenfeld, B. J. (2019). Biomechanical, anthropometric, and psychological determinants of barbell back squat strength. The Journal of Strength & Conditioning Research, 33, S26-S35.

Van Oosterwijck, J., De Ridder, E., Vleeming, A., Vanderstraeten, G., Schouppe, S., & Danneels, L. (2017). Applying an active lumbopelvic control strategy during lumbar extension exercises: Effect on muscle recruitment patterns of the lumbopelvic region. Human movement science, 54, 24-33.

Wirtz, N., Zinner, C., Doermann, U., Kleinoeder, H., & Mester, J. (2016). Effects of loaded squat exercise with and without application of superimposed EMS on physical performance. Journal of sports science & medicine, 15(1), 26.

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