The muscles in our body perform various functions such as helping with blood circulation, digesting food, and moving parts of the body. The three types of muscles cells found in the body are the cardiac, smooth, and skeletal muscle cells. The purpose of this lab was to determine the relationship between muscle force and EMG activity, and to examine the effects of muscle size and muscle force. In this lab, we used iWork physiology kit to record the bursts of muscle action potentials during a muscle contraction which is also known as an electromyogram (EMG). We then used this data to compare the maximum muscle force, half-maximum muscle force, and the half- maximum fatigue time to a person’s forearm circumference (muscle size).
After performing the EMG and Grip
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Muscle fatigue is the inability to maintain muscle tension at a given level. According to Table 1, my maximum muscle force was 25kg. After 53.33s (half-max fatigue time) into the exercise I started to experience muscle fatigue and my half-maximum muscle force was 12.5kg. Some of the causes of muscle fatigue are due to lack of sleep, aging, heavy exertion, and medication side effects. Physiologically muscle fatigue can be caused by the accumulation of lactic acid in the blood, ion imbalance within the muscle, and depletion of glycogen or ATP. Lastly, Figure 2 and Figure 3 represent a collection of data obtained from the students in class. To determine a correlation between two variables we used the “coefficient of determination” which is also known as r-squared. Based on Figure 2, the r-squared value was 0.292. This r-squared value indicated that there appears to be no relationship between the muscle size and maximum muscle force. In comparison, in Figure 3 the r-squared value was 0.038. Thus, this r-squared value also indicated that there is no relationship between the muscle size and half-maximum fatigue
The data was recorded for ten minutes. The last segment in the data collection was to analyze the effects of direct electrical stimulation. The hook electrode was disconnected and two electrode needles were inserted about five mm from each end of the gastrocnemius muscle. Starting at the maximum voltage from the first experiment, voltage was slowly increased until a twitch appeared. Then voltage was set to ten times the maximum voltage from the first experiment.
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.
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)
•Controlled variable- amount of time exercising and resting, number of trials, type of exercise, same type of clothespin , intensity of the exercise, and the age of test subjects
In this lab, we explored the theory of maximal oxygen consumption. “Maximal oxygen uptake (VO2max) is defined as the highest rate at which oxygen can be taken up and utilized by the body during severe exercise” (Bassett and Howley, 2000). VO2max is measured in millimeters of O2 consumed per kilogram of body weight per min (ml/kg/min). It is commonly known as a good way to determine a subject’s cardio-respiratory endurance and aerobic fitness level. Two people whom are given the same aerobic task (can both be considered “fit”) however, the more fit individual can consume more oxygen to produce enough energy to sustain higher, intense work loads during exercise. The purpose of this lab experiment was performed to determine the VO2max results of a trained vs. an untrained participant to see who was more fit.
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.
The contraction of a muscle is a complex process, requiring several molecules including ATP and Cl-, and certain regulatory mechanisms [1]. Myosin is motor protein that converts chemical bond energy from ATP into mechanical energy of motion [1]. Muscle contraction is also regulated by the amount of action potentials that the muscle receives [2]. A greater number of actions potentials are required to elicit more muscles fibers to contract thus increasing the contraction strength [2]. Studied indicate that the larger motor units, which were recruited at higher threshold forces, tended to have shorter contraction times than the smaller units [3]. The aims of the experiment were to reinforce the concept that many chemicals are required for skeletal muscle contraction to occur by using the rabbit muscle (Lepus curpaeums) [2]. In addition, the experiment was an opportunity to measure the strength of contraction and to observe the number of motor units that need to be recruited to maintain a constant force as the muscles begin to fatigue [2]. Hypothetically, the rabbit muscle fiber should contract most with ATP and salt solution; and the amount of motor units involved would increase with a decreasing level of force applied until fatigue stage is reached.
The muscular strength is highly affected by the nervous system. Emotional and mental factors play important part in strength testing. If a subject is consistent with motivation strength variability should be minimized. In women a daily variation in strength range is between 2 and 12% and 5 to 9% in men.
Sewall, R., et al. Strength Development in Children. (abstract). Medicine and Science in Sports and Exercise. 16:158. 1984.
In this report, I will be writing about the data that was collected from the beep test, which tests the aerobic endurance of the participants who are performing the test. With the results collected I will be discussing the different factors that may have impacted on the participant’s results. Robinson (2010) states that there are different systems in the body such as the skeletal, muscular, circulatory, and respiratory. Despite the fact all these systems are separate, they are all linked together to help the functioning of the body when at rest and during exercise. When the body begins to participate in exercise, during physical activity changes start to occur in the cardiovascular system starts so that it can adapt to the physical activity, this links into Kenney et al, (2012) where they indicate that cardiovascular changes occur when the body starts to move during exercise, and that the main reason for this is so that the blood flow increases to the working muscles. Furthermore, there are other adjustments in the cardiovascular system, where the ‘blood flow patterns change significantly in the change from rest to exercise. Through the vasoconstrictor action of the sympathetic nervous system on local arterioles, blood flow is redirected away from areas where elevated flow is not essential to those areas that are active during exercise, only 15% to 20% of the resting cardiac output goes to muscle, but during high-intensity exercise, the muscles may receive 80% to 85% of the cardiac output.’ (Kenney et al, 2012:190)
Investigating the Effect of Exercise on the Heart Rate Introduction For it's size the heart has the huge capacity of pumping large amounts of blood, in the average adult's heart beats 60 to 100 times a minute, pumps between 70ml and 100ml of blood with each beat, circulates 5 to 6 litres of blood around the body per minute and about 13 litres of blood per minute during vigorous exercise. The heart will beat more then 2.5 billion times during an average lifetime. This investigation will be looking at the effect of exercise on the heart rate. Aim The aim of this investigation is to find out how exercise affects the heart rate, using research & experimenting on changes and increases in the heart rate using exercise. Research â— The heart The normal heart is a strong, hardworking pump made of muscle tissue.
Gabboth, Tim. "Journal of Strength & Conditioning Research (Lippincott Williams & Wilkins). Feb2012, Vol. 26 Issue 2, P487-491. 5p." N.p., n.d. Web.
Studies have shown that initial increases in strength seen in the beginning stages of strength training programs are largely due to neural factors, even though, the process responsible for muscle growth is evident in early weeks of training. Research shows that different types of neural adaptations like enhanced coordination and increased voluntary activation of major muscles are responsible for these early increases in strength (Sale, 1988, p. S142). Muscle strength is measured by the maximum amount of torque a muscle can produce during a maximal voluntary contraction (MVC) (Duchateau, Semmler & Enoka, 2006, p. 1768). Since humans cannot completely activate a muscle voluntarily, strength training can help increase the amount of muscle a person can activate voluntarily (Gabriel, Kamen & Frost, 2006, p. 135). Some data suggest that the pattern of motor unit activation and the number of motor units activated are equally as important the frequency of activation in producing increased strength (Gabriel, Kamen & Frost, 2006, p. 136). When an individual performs specific exercises repeatedly the motor units that control the activated muscles learn to activate in a simultaneous pattern, increasing strength. This can lead to intermuscular coordination allowing muscles to distribute motor unit activation among the muscles involved in particular exercises. Changes in the capability to distribute muscle activation may be due to the ability to voluntarily activate the muscles needed for specific task (Duchateau, Semmler & Enoka, 2006, p. 1769). Explosive power...
For the Maragaria-Kalamen Power Test, the subject ran up a flight of stairs as fast as possible to determine the power output capabilities of specific muscles including quads, hamstrings, planter and dorsal flexors. The subject started 12” behind the first step. Next, the subject ran up the stairs as fast as possible, taking two steps at a time. As soon as the subject’s foot touched the second stair, a timer started the stopwatch. The timer stopped the stopwatch when the subject reaches the landing. This was a total vertical distance of 1.80 meters. This test becomes difficult for some when having to jump more than one step. Each subject completed the test a total of three times and the times were recorded. Once all three times were recorded for the subject, the experimenter took the best time. To find the power for the male and female subjects, the experimenter used the formula Power=Force x Distance / Time. Force was the body weight of the subject in kilograms. The distance was the vertical distance of the stairs, which was 1.8 meters. The time was the best of the three times recorded for each subject, in seconds. After calculating the power, the experimenter used the classification chart for the Margaria Kalamen power test to classify the subject’s power. After finding the power for each subject, the experimenter averaged the power of all three female subjects to get the female subject mean
The muscular system is a very important part of the human body. It has many components and functions, and is the source of the body’s movement. There are roughly 650 muscles in the human body and are different types of muscles. Muscles can either be voluntary or involuntary which means controlled or uncontrolled movement. Muscles have many reasons and in this paper you will widen your knowledge of muscles and their functions as well their diseases and how they help maintain the body.