1. Contrast the differences between force and torque. Use each term to describe a particular aspect of a muscle’s contraction relative to a joint. (6 pts)
According to Neumann, a force can be considered a push or pull that can produce, arrest or modify movement and can be measured as F=ma (Neumann, 2010). Force can also be considered the load. In regards to muscle contraction force relative to the joint, the force can be the internal force produced by the muscle itself, the force of gravity or the force of the particular load/weight. Torque is a cross product between force and the distance of the force from the fulcrum and is the ability of a force to cause rotation on a lever. Torque is a measure of how much a force acting on an
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With the longer lever I would also not need to provide as much force as with the shorter one. I would consider the tire iron a 3rd class lever as the axis of rotation would be the nut on the tire, the force in the middle would be from gravity and the resistance opposite of the axis would be the force I applied to either tighten or loosen nut.
3. When performing manual muscle testing for shoulder flexion or abduction, why do PTAs typically place their hand at the wrist versus mid-extremity? Think about torque and actually try it on a friend. (2 points)
When performing manual muscle testing for shoulder flexion and abduction, PTA’s typically place their hand at the wrist verses the mid-extremity because placing their hands at the wrist increases the length of the lever thus testing the muscles ability to resist externally applied force overtime and across the bone-joint lever arm system. Shorter lever arms will provide higher testing scores when compared to using longer lever arms, thus changing the point of force application affects the length of the lever arm and therefore the muscle torque.
4. How does the length of a moment arm correlate to torque generating capability? (3
Prior to intubation for a surgical procedure, the anesthesiologist administered a single dose of the neuromuscular blocking agent, succinylcholine, to a 23-year-old female to provide muscular relaxation during surgery and to facilitate the insertion of the endotracheal tube. Following this, the inhalation anesthetic was administered and the surgical procedure completed.
Another weakness in the experimental design was that the reliability of the experiment was very low. As each test subject was only tested against each amount of prior exercise once, the impact of random errors is likely very large, which can be seen by the spread of the data on the graph. Although, this was attempted to be rectified by averaging the results of all four test subjects, it does not improve reliability too much. Conclusion: The results of this investigation indicated that a relationship between the amount of prior exercise and muscle fatigue does exist, however the results are also not conclusive enough to speculate on what the relationship is. This means that the hypothesis “If the amount of time spent performing vigorous exercise prior to the set of repetitions increases, then the physical performance (number of repetitions) will decrease” cannot be supported or rejected due to the inconclusive data.
The protocol and conceptual overview of these procedures can be found under the header, “Properties of Skeletal Muscle” in NPB 101L Physiology Lab Manual Second Edition (Bautista & Korber, 2009, 9-17). The test subject for this lab was the Northern Leopard frog whose spinal cord and brain were severed. In order to carry out the experiments, the materials needed were one medium length surgical scissor, two hemostats and glass dissecting probes, a nine and four inch string, a cup of Ringers saline solution with an eyedropper, and a hook electrode. The software used to analyze and record the data was the BIOPAC system.
Over a three week period a test subject was instructed to come to the exercise physiology lab once a week. The purpose of the first week was to determine the baseline test data for the participant. During this first week, the subject was asked how many hours of sleep they had gotten the night before and how much they weighed. The subject was then instructed to put on a heart monitor and wear an O2 apparatus and begin running on a treadmill. This treadmill was set at zero incline for the beginning of the run until three minutes had passed. At the three minute mark the incline increased by 2.5%. After this the incline was continuously increased by 2.5% every two minutes. During this process, the VO2 and RER exchange rate of the subject was being tracked through the O2 apparatus. Their heart rate was recorded every 15 seconds. In addition, the subject was asked their perceived exertion at every increase in incline. The subject continued to run until they could not run anymore, at this time they would hop off the treadmill.
The subject’s forearm was prepared by cleaning the surface of their skin (the flexor digitorum superficialis muscle) and the bony prominence of their wrist with an alcohol swab, and the EMG adhesive electrodes where placed on the belly of the flexor digitorum superficialis muscle. The positive electrode was placed more proximal to the elbow, while the negative electrode was placed more mid-distally. The grounding (noise reducing) electrode was places on the bony prominence of the wrist, and the force transducer was setup to achieve a stable baseline. The subject was then instructed to the support their forearm over the edge of the table or on their leg with the wrist in a semi-flexed position, and when ready squeeze the force grip transducer as hard as possible. For the first/”fast” time interval of the experiment, the subject made ten squeezes as fast as possible with one second per squeeze intervals, and the force onset, EMG onset, difference between force onset and EMG onset, peak EMG amplitude, and peak force amplitude were observed and recorded. The experiment was then repeated for a medium, three seconds per squeeze, and slow, five seconds per squeeze time intervals with the same variables observed and
The all too familiar "pop!" immediately followed by weakness, pain, and immobility; the classic signs of a shoulder injury. Many shoulder injuries affect the rotator cuff. "Each year approximately 200,000 American require surgery related to the repair of the rotator cuff" (Yamaguchi). This vast number of surgeries makes shoulder injuries a popular topic in the medical field. Physicians have been researching ways to improve patients' recovery and return their range of motion back to normal. One such improvement is the release of the long head of the biceps tendon.
This report will explore the structure and function of skeletal muscle within the human body. There are three muscle classifications: smooth (looks smooth), cardiac (looks striated) and skeletal (looks striated). Smooth muscle is found within blood vessels, the gut and the intestines; it assists the movement of substances by contracting and relaxing, this is an involuntary effort. The heart is composed of cardiac muscle, which contracts rhythmically nonstop for the entire duration of a person’s life and again is an involuntary movement of the body. The main focus of this report is on skeletal muscle and the movement produced which is inflicted by conscious thought unless there is a potentially harmful stimulus and then reaction is due to reflex, as the body naturally wants to protect itself. Skeletal muscle is found attached to bones and when they contract and relax they produce movement, there is a specific process that the muscle fibers go through to allow this to occur.
Cardiovascular Activity And How it Influences the body. Introduction: Cardiovascular fitness is a form of aerobic fitness (Neporent and Egan 1997). There are many different ways of evaluating the amount of oxygen used during cardiovascular fitness and one the methods involved is called VO2 Max. VO2 Max is the maximum amount of oxygen that the body can hold.
Rigid body motion does not change the length of a vector joining the pair of points inside the body and has no concern with the strain analysis. When external forces are applied on an elastic body, the body undergoes deformation. Due to the elasticity of the body, there comes into play a force which resists the deformation. This force is called stress force. Clearly, the deformation of the body is accompanied by the stress force. In other words, stress and strain occur together in inelastic body. There are two types of elastic deformation: (i) Dilatation and (ii) Shear strain set up in the body in such a way that there is a change only in volume but no change in shape, is called dilatation. In the shear deformation, there is a change in the shape of the body without a change in its volume. Dilatations are further categorized into two kinds: compression, in which volume is reduced; and rarefaction, in which the volume is
Controlled increases in physical stress through progressive resistive exercise cause muscle fibers to hypertrophy and become capable of generating greater force.3 Early emphasis is on restoring joint range of motion and muscle flexibility, however, resistive exercises are not delayed. The initial emphasis of muscle loading should be on endurance, accomplished with lower loads and higher repetitions. Progressive resistive exercises are initiated at the available range and progressed to new positions as wrist range of motion returns in all planes. Both the overload principle and the SAID Principle (Specific Adaptation to Imposed Demands) are important considerations in therapeutic exercise dosing.1,3,11 Within pain tolerance, dosing progressive resistive exercises that maintain a therapeutic stress level will encourage muscle tissue hypertrophy. Finding activities that produce the correct force and repetition, without injury, is the goal of the remobilization period. Starting with low force, moderate to high repetitions, and encouraging therapeutic rest following induced stress is important to both the overload principle and the SAID Principle. Additionally, it is important to prevent dosing resistive exercises that exceed optimal stress, which may result in injury. The patient’s response to therapeutic exercise should be assessed during, immediately following,
This case involved a 53 year old man who sustained a significant tear of his rotator cuff while playing baseball. He underwent surgical repair and was given a referral for physical therapy. The referral was to begin passive ROM 3 times per week for 2 weeks then initiate a supervised home program of active exercise for 2 weeks, and elastic resistance exercises for internal and external rotation every other day for a month. 2 weeks after surgery, he had his first PT visit in a sports medicine clinic that was managed by an athletic trainer (ATC).”
The purpose of this experiment was to gather data on how the amount of time spent active impacts the speed of heart rate in beats per minute. The hypothesis stated that if the amount of time active is lengthened then the speed of the heart rate is expected to rise because when one is active, the cells of the body are using the oxygen quickly. The heart then needs to speed up in order to maintain homeostasis by rapidly providing oxygen to the working cells. The hypothesis is accepted because the data collected supports the initial prediction. There is a relationship between the amount of time spent active and the speed of heart rate: as the amount of time spent active rose, the data displayed that the speed that the heart was beating at had also increased. This relationship is visible in the data since the average resting heart rate was 79 beats per minutes, while the results show that the average heart rate after taking part in 30 seconds of activity had risen to 165 beats per minute, which is a significantly larger amount of beats per minute compared to the resting heart rate. Furthermore, the average heart rates after 10 and 20 seconds of activity were 124 and 152 beats per minute, and both of which are higher than the original average resting heartbeat of 79.
AIM: - the aim of this experiment is to find out what the effects of exercise are on the heart rate. And to record these results in various formats. VARIABLES: - * Type of exercise * Duration of exercise * Intensity of exercise * Stage of respiration
Lee BG, Cho NS, Rhee YG. Effect of two rehabilitation protocols on range of motion and healing rates after arthroscopic rotator cuff repair [aggressive versus limited early passive exercises]. Arthroscopy. 2012 Jan;28(1):34-42. http://www.ncbi.nlm.nih.gov/pubmed/22014477. Accessed May 7, 2014. PMID: 22014477.