Stress Levels Measured through Salivary Cortisol in Nationally Ranked Fencers

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Description
Salivary cortisol is the least invasive way in measuring hormonal response during exercise without interruption. In nationally ranked fencers (n=21), changes in cortisol were monitored by measurement of salivary cortisol sampled throughout different rounds of three North American Cup tournaments

Salivary cortisol is the least invasive way in measuring hormonal response during exercise without interruption. In nationally ranked fencers (n=21), changes in cortisol were monitored by measurement of salivary cortisol sampled throughout different rounds of three North American Cup tournaments during the 2017-2018 United States fencing season. The changes were also compared when looking at if a bout ended in a victory or defeat; the difference in rank between opponents; and the difference in score at the end of the bout. Immediately before the tournament cortisol levels were sampled, changes were in comparison to the initial sample as well as change from one bout to the next. The primary purpose of this study was to (a) compare how cortisol levels fluctuate during a tournament and (b) analyze cortisol levels to see if there is an optimal rage for performance. Eustress, “good stress” was considered optimal when the athletes were at peak performance. Here, peak performance means accomplishing the task, with the task being the bout ending in a victory. It was hypothesized that (a) cortisol levels would peak after a loss or stressful bout and (b) there would be an optimal range of cortisol for peak performance. This study supports the findings that cortisol peaks after a loss, and could point to optimal cortisol levels being more of an individualized range for each athlete. If these athletes can explicitly see just how their hormones rise and fall, then perhaps being more aware of these levels and being able to embrace them could lead to peak performance.
Date Created
2018
Agent

Metabolic Adaptations to Aerobic Exercise: A Review

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Description
Adenosine triphosphate (ATP) is the driving force of the human body which allows individuals to move freely. Metabolism is responsible for its creation, and research has indicated that with training, metabolism can be modified to respond more efficiently to aerobic

Adenosine triphosphate (ATP) is the driving force of the human body which allows individuals to move freely. Metabolism is responsible for its creation, and research has indicated that with training, metabolism can be modified to respond more efficiently to aerobic stimulus. During an acute bout of exercise, cardiac output increases to maintain oxygen supply to the body. Oxidative muscle fibers contract to move the body for prolonged periods of time, creating oxidative stress which is managed by the mitochondria which produce the ATP that supplies the muscle fiber, and as the body returns to its resting state, oxygen continues to be consumed in order to return to steady state. Following endurance training, changes in cardiac output, muscle fiber types, mitochondria, substrate utilization, and oxygen consumption following exercise make adaptations to make metabolism more efficient. Resting heart rate decreases and stroke volume increases. Fast twitch muscle fibers shift into more oxidative fibers, sometimes through mitochondrial biogenesis, and more fat is able to be utilized during exercise. The excess postexercise oxygen consumption following exercise bouts is reduced, and return to steady state becomes quicker. In conclusion, endurance training optimizes metabolic response during acute bouts of aerobic exercise.
Date Created
2018-05
Agent

Preferred Versus Recommended Saddle Height For Optimal Cycling Economy

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Description
The purpose of this study was to analyze the effects of changing a saddle height to a scientifically recommended position on cycling economy for competitive cyclists. Participants completed one maximal effort graded exercise test and two sub-maximal 70% economy trials,

The purpose of this study was to analyze the effects of changing a saddle height to a scientifically recommended position on cycling economy for competitive cyclists. Participants completed one maximal effort graded exercise test and two sub-maximal 70% economy trials, one at the cyclist’s original saddle height and the second at the saddle height corresponding with a knee flexion angle of 25° at full pedal extension. Due to experimental error and equipment failure heart rate became the main performance measure and cycling economy tests were conducted at an average of 84.4% of heart rate max. The results revealed no apparent differences in performance between the recommended and original saddle height. However, 2D analysis of dynamic knee angles revealed that at the 25° knee angle condition, knee angle increased by an average of 16.1% from the static position (average dynamic knee angle = 29.02±4.61°). Dynamic measures (32.59±4.88°) taken during the original angle tests were only slightly augmented compared to the static measure (31.5±2.18°). It is possible based on this trend that a difference in performance values was not present because the change between the original angle and the experimental angle was not substantial. Additionally these findings suggest that cyclists adjust to these acute changes in saddle height by altering other kinematic variables in an attempt to find a comfortable position and perform maximally.
Date Created
2013-05
Agent

DIFFERENCES IN UNILATERAL CHEST PRESS MUSCLE ACTIVATION ON A STABLE VERSUS UNSTABLE SURFACE WHILE HOLDING ONE VERSUS TWO DUMBBELLS

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Description
Training the bench press exercise on a traditional flat bench does not induce a level of instability as seen in sport movements and activities of daily living. Because of this, many new types of equipment have been created in an

Training the bench press exercise on a traditional flat bench does not induce a level of instability as seen in sport movements and activities of daily living. Because of this, many new types of equipment have been created in an attempt to induce instability, such as the COR Bench. 15 males and 7 females between the ages of 18 and 30 were recruited for the present study, which tested two forms of instability: using one dumbbell rather than two, and lifting on the COR bench compared to a flat bench. Thusly, EMG was used to measure muscle activity in four separate conditions of unilateral bench press movements: on a flat bench with one dumbbell, on a flat bench with two dumbbells, on the COR Bench with one dumbbell, and on the COR Bench with two dumbbells. Results indicated that lifting with one dumbbell compared to two dumbbells on the flat bench significantly increased muscle activity across all four muscles being analyzed (pectoralis major, p = .005; middle trapezius, p = .008; external obliques, p = .004; and internal obliques, p = .003), but lifting with one dumbbell compared to two dumbbells on the COR Bench only significantly increased muscle activity in the middle trapezius (p = .001), external obliques(p = . 032), and internal obliques (p = .001). The only muscle to exhibit a significant increase in muscle activity when going from one dumbbell on the flat bench to one dumbbell on the COR Bench was the middle trapezius (p = .010). These results imply that the COR Bench itself does not increase muscle activity as much as switching from two dumbbells to one dumbbell, regardless of the bench being used.
Date Created
2013-12
Agent

FOOT STRIKE AND INJURY RATES IN ENDURANCE RUNNERS: A RETROSPECTIVE STUDY- REVISITED

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Description
Although the sport and exercise of running has a great amount of benefits to anyone's health, there is a chance of injury that can occur. There are many variables that can contribute to running injury. However, because of the vast

Although the sport and exercise of running has a great amount of benefits to anyone's health, there is a chance of injury that can occur. There are many variables that can contribute to running injury. However, because of the vast amount of footsteps a frequent runner takes during their average run, foot strike pattern is a significant factor to be investigated in running injury research. This study hypothesized that due to biomechanical factors, runners that exhibited a rear foot striking pattern would display a greater incidence of chronic lower extremity injury in comparison to forefoot striking counterparts. This hypothesis would support previous studies conducted on the topic. Student-athletes in the Arizona State University- Men's and Women's Track & Field program, specifically those who compete in distance events, were given self reporting surveys to provide injury history and had their foot strike patterns analyzed through video recordings. The survey and analysis of foot strike patterns resulted in data that mostly followed the hypothesized pattern of mid-foot and forefoot striking runners displaying a lower average frequency of injury in comparison to rear foot strikers. The differences in these averages across all injury categories was found to be statistically significant. One category that displayed the most supportive results was in the average frequency of mild injury. This lead to the proposed idea that while foot strike patterns may not be the best predictor of moderate and severe injuries, they may play a greater role in the origin of mild injury. Such injuries can be the gateway to more serious injury (moderate and severe) that are more likely to have their cause in other sources such as genetics or body composition for example. This study did support the idea that foot strike pattern can be the main predictor in incidence of running injuries, but also displayed that it is one of many major factors that contribute to injuries in runners.
Date Created
2014-05
Agent

Effects of a fat-sugar supplemented diet, with and without exercise training, on endothelial function, blood pressure, and markers of cardiovascular risk

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Description
The Western Pattern diet has been characterized by having greater than 50 percent consumption coming from fat and sugar. This macronutrient allocation has been shown to have deleterious effects on endothelial function and metabolic markers of cardiovascular disease. Exercise has

The Western Pattern diet has been characterized by having greater than 50 percent consumption coming from fat and sugar. This macronutrient allocation has been shown to have deleterious effects on endothelial function and metabolic markers of cardiovascular disease. Exercise has been shown to improve vascular reactivity and metabolic markers related to cardiovascular health. The objective of the study was to determine if exercise training can prevent the anticipated deleterious effects of a fat-sugar supplemented diet on endothelial function and blood markers of cardiovascular risk in young men. Twenty-one, healthy college-aged males were randomly assigned to either the doughnut + exercise or doughnut only groups. Both groups were fed 2 doughnuts per day, 6 days per week, for three weeks, while maintain their current diet. The exercise group completed 4 exercise training sessions per week consisting of 2 high intensity interval training bouts (up to 95% VO2peak) on a cycle ergometer and two moderate intensity, steady-state bouts (at 75% VO2peak) on a treadmill. Changes in body weight and composition, markers of endothelial function, oxidative stress, serum lipids, and blood glucose were measured in each group. As expected, cardiovascular fitness increased significantly in the doughnut-supplemented + exercise group as compared to the doughnut-supplemented (p=0.005). Significant increases in body weight (p=0.036), fat mass (p=0.013), and body fat percentage (p=0.014) were seen in the doughnut only group as compared to the doughnut + exercise group. The doughnut + exercise group showed significant improvements in fasting serum triglycerides (p=0.036), plasma insulin (p=0.039) and insulin sensitivity (HOMA; p=0.05) as compared to the doughnut only group. The doughnut + exercise group saw a significant improvement in nitric oxide availability whereas the doughnut only group experienced a significant decline (p=0.014). There were no significant changes in other markers. Despite the addition of a fat/sugar supplement of ~11,600 kcal over three weeks, 4 exercise sessions per week were sufficient to prevent a gain in body weight and fat mass, and also improve some measures of cardiometabolic risk. These results suggest that exercise may be necessary to prevent some adverse health outcomes associated with transient periods of excessive energy consumption.
Date Created
2013
Agent