Background: According to the Center for Disease Control and Prevention, approximately 1.6 to 3.8 million Americans suffer a sports related concussion each year. Concussion is defined as a transient alteration of the brain structure caused by a direct or indirect force. During the last decade, a vast amount of clinical research on the long term effects of repetitive head trauma has occurred, especially on the subject of chronic traumatic encephalopathy (CTE), depression and dementia. Objective: The purpose of this literature review is to examine the literature pertaining to multiple concussion and the long-term effects of multiple concussion such as neurodegenerative diseases and psychological. Methods: A literature review was conducted using an electronic search of the following databases: MEDLINE, Cochrane Database of Systematic Reviews, and SportDiscus. The key search terms included were concussion, "sport concussion" and "sports concussion". One of the above three terms needed to be in conjunction with one of the following key search terms: depression, dementia, "mild cognitive impairment", "chronic traumatic encephalopathy" (CTE), or "psychological disorder". Additional inclusion criteria also included studies that targeted the adult athlete population who had sustained more than one concussion. Studies only were included if they were peer-reviewed, in the English language, and were published after 1990. To be included in the review, the study must have examined the long term effects of repetitive concussion. Results: The research completed to date suggests there is a strong correlation between the number of concussions an athlete suffers and the long-term ramifications of neurodegenerative and psychological disorders. However, more research is needed.

The overall purpose of this dissertation was to assess the Weightlifting team’s athlete and coach perception of the athlete monitoring program at East Tennessee State University over the course of a mesocycle. This was accomplished by conducting a single investigation using eleven well-trained weightlifters and three coaches. Five data collections were carried out over the course of a single mesocycle leading up to a competition. No statistically significant perceptual changes throughout the training program were observed among any questions for weightlifters or coaches. Interpretation of the means for each question indicate that both weightlifters’ and coaches’ perceptions of the SPEC program’s ability to influence the components assessed by the questionnaire were positive ranging from no different to much better. Participants agree that they do understand why they take part in both SPEC testing and monitoring, and coaches indicated that data from testing and monitoring is used to develop and alter their athletes training. Results further indicate regular communication between coaches and their athletes about the purpose of their programming.

This study investigated changes in maximal jump performance in response to match play induced fatigue. During six sets of tournament match play, seven National Association of Intercollegiate Athletics women’s volleyball athletes accumulated a mean Player Load of 758.6±216.89 au (measured via microsensor accelerometry), and mean session rate of perceived exertion of 1184.1±363.2. Repeated measures ANOVAs were used to identify change with Hedge’s g effect sizes used to assess magnitude of change. Short recovery stress scale results indicated elevated stress (ES=1.401 to 1.588) and decreased recovery (ES = -1.358 to -1.848) 24 hours post-match, trending towards baseline 48 hours post-match. Countermovement jump height (CMJH) decreased immediately post-match (p<0.01, ES= -0.216), partially recovered Post24 (p=0.109, ES=0.130), and fully recovered by Post48 (p < 0.01, ES=0.216). It was concluded that match-play may have contributed to the observable decline in post-match maximal jump performance, and CMJH testing may be an effective assessment of acute neuromuscular status.

Glaister, M., M.H. Stone, A.M. Stewart, M.G. Hughes, and G.L. Moir. The influence of endurance training on multiple sprint cycling performance. J. Strength Cond. Res. 21(2):606-612. 2007. - The aims of the present study were to examine the effects of endurance training on multiple sprint cycling performance and to evaluate the influence of recovery duration on the magnitude of those effects. Twenty-one physically active male university students were randomly assigned to either an experimental (n = 12) or a control (n = 9) group. The experimental group cycled for 20 minutes each day, 3 times per week, for 6 weeks at 70% of the power output required to elicit maximal oxygen uptake (Vo2max). Multiple sprint performance was assessed using 2 maximal (20 × 5 seconds) sprint cycling tests with contrasting recovery periods (10 or 30 seconds). All tests were conducted on a friction-braked cycle ergometer. Relative to controls, training resulted in a 0.2 L·min -1 increase in mean Vo2max (95% likely range: -0.04 to 0.44 L·min-1). Changes in anaerobic capacity (determined by maximal accumulated oxygen deficit) over the same period were trivial (p = 0.96). After training, the experimental group showed significant improvements (∼40 W), relative to controls, in multiple sprint measures of peak and mean power output. In contrast, training-induced reductions in fatigue were trivial (p = 0.63), and there were no significant between-protocol differences in the magnitude of any effects. In summary, 6 weeks of endurance training resulted in substantial improvements in multiple sprint cycling performance, the magnitude of the improvements being largely unaffected by the duration of the intervening recovery periods.

The purpose of this study was to investigate the effects of accentuated eccentric load (AEL) resistance training and changes in work capacity, high-intensity exercise endurance (HIEE) and lactate metabolism. Seventeen recreationally trained subjects (11 males and 6 females) (mean ± SD: age = 23.2 ± 4.2 yrs, BM = 81.3 ± 22.2 kg, height = 172.1 ± 10 cm, male relative back squat (BS) [MD1] strength (1RM*BM-1) = 1.64 ± 0.32 kg*kg-1, female relative BS strength = 1.39 ± 0.32 kg*kg-1) participated in the study. Subjects completed a week of familiarization to participate in a week of pre-testing, 4 weeks of strength endurance (S-E) training (3 weeks of increasing intensity with 1 deload week) followed by a final week of post-testing. Subjects were randomly assigned into AEL and traditional (TRAD) resistance training groups, pair matched for relative strength. The AEL subjects performed 3 sets of 10 reps for all multi-joint compound movements where 5 AEL repetitions were performed within the set followed by a traditional repletion and 15 s intraset rest to reattach AEL equipment, like a cluster set (CS) protocol. Resistance training was performed 3 days a week with sprint and agility training two days a week. Maximal BS strength (1RM) and HIEE were tested pre and post training block. HIEE was tested in an incremental exercise test to failure, starting at an initial load of 40kg for 10 reps/min with 2min rest to increase load. Additionally, blood lactate concentrations (BLa) were collected at baseline before any exercise was performed, after warming up, after stage three of HIEE, immediately after the final repetition, 5- and 10- minutes post final repetition. While over time maximal strength and work capacity increased no statistical difference was observed between AEL and TRAD groups after training. Additionally, there were no statistically significant differences in the BLa at similar time points pre and post. Statistically significant correlations were found between strength (squat 1RM) and work capacity, however, strength failed to account for a majority of the variance in the observed data. [MD1]Back Squat (BS)

The sport of weightlifting has been competed since the first modern Olympiad. Competition in weightlifting consists of 3 attempts the snatch and clean and jerk declared by the athlete and their coach prior to the starting of the lift. While waiting for the athlete’s lift, waiting periods can change and warm up attempts may need to be adjusted. Often, coaches prescribe either a complete “light power” or partial “heavy pull” repetition of the competed movement during a long wait. Previous literature indicates that a heavier stimulus may cause a “post-activation potentiation”, or “post-activation performance enhancement” effect on the subsequent lift. However, some evidence indicates that a heavy pull closely preceding a subsequent clean may disrupt technique. Despite the common practice to perform a heavy pull or lighter power clean or snatch in the warmup area, little information is known about whether this movement will potentiate the following repetition or disrupt technique. The purpose of this investigation was to investigate the potentiation and technique effects of the heavy pull and light power on a subsequent clean. Methods: The subjects (males n = 9; females n= 2) were eleven well-trained athletes (weightlifting, track and field, crossfit) in the clean. After warmup, a series of cleans were performed leading to a 90 % 1 RM clean followed by a 75% power clean or 112% clean pull (order randomly assigned), this was followed by a 90% clean. Kinematics were measured using Qualisys M3 motion capture. Subjective effort was measured after each 90% clean using rating of perceived exertion (RPE). Results: Men were stronger than women how ever there was no difference in the outcome. Peak bar velocity was not statistically different pre-post (p≥ 0.5). Vertical displacement was not statistically different pre-post (p≥ 0.5). Horizontal displacement was not statistically different (p≥ 0.5). Catch phase duration was not statistically different (p≤ 0.5), however effect size indicates small to moderate decreases in duration in both conditions. Stronger athletes appeared to have less technical disruption compared to lesser lifters. Following the power clean there was a statistically significant reduction in RPE (p ≤0.5, cohen’s d=0.595 95%CI=0.171 to 1.02).

Objective: The primary aim of this research was to examine the temporal pattern of neuromuscular quadriceps deficits in both the involved and uninvolved limbs of patients assigned to the control group after anterior cruciate ligament reconstruction (ACLr), by assessing quadriceps strength, voluntary activation, and corticomotor excitability prior to surgery (baseline), three months after ACLr, and six months after ACLr. A secondary aim of this research was to determine whether quadriceps strength, voluntary activation, and/or corticomotor excitability assessed in patients prior to ACLr and/or at three months after surgery, is predictive of lower extremity postural control and/or self-reported function at six months after ACLr. Lastly, a tertiary aim of this research was to determine if a 12-week home-based neuromuscular electrical stimulation (Home-NMES) program elicits greater bilateral improvements in quadriceps strength, voluntary activation, and corticomotor excitability of patients at three and six months after ACLr compared to a 12-week standard home-exercise program (control group). Participants: Fifty patients scheduled to undergo unilateral ACLr were randomly allocated to the home-NMES group (19 Female, 6 Male; age: 18.9 ± 5.4 years; height: 170.8 ± 9.7 cm; weight: 74.6 ± 18.5 kg; 28.0±20.0 days-post-injury) or control group (14 Female, 11 Male; age: 19.4 ± 4.5 years; height: 171.1 ± 11.5 cm; weight: 70.7 ± 11.9 kg). Methods: A randomized clinical trial design was used in this study. Prior to ACLr, isometric quadriceps strength and voluntary quadriceps activation were assessed in both limbs of patients, and corticomotor excitability was assessed in the involved limb. Three days after ACLr, both groups were instructed to begin their allocated interventions. The Home-NMES group administered NMES to their involved limb’s quadriceps three sessions a day for 15 minutes, and five days a week for 12 weeks using a portable NMES device. The control group was treated according to the current standard-of-care, but they were also instructed to perform volitional isometric quadriceps contractions for the same duration and frequency as the Home-Based NMES protocol. The outcomes measures were reassessed in both groups at three and six months post-ACLr. Main Outcome Measures: Quadriceps strength and voluntary activation were assessed using maximal voluntary isometric contractions and the superimposed burst technique, respectively. Normalized peak knee extension torque and central activation ratio were used to quantify isometric quadriceps strength and activation, respectively. Corticomotor excitability was evaluated with transcranial magnetic stimulation, and quantified with active motor threshold). The Y-balance test anterior reach (YBT-A) and Knee Injury and Osteoarthritis Outcome Score (KOOS) were used to assess the patients lower extremity knee function at six months post-ACLr. Statistical Analyses: Specific Aim 1: A 2x3 (limb x time) mixed model, ANOVA with repeated measures was performed in the control group to assess differences between the involved limb and the uninvolved limb for isometric quadriceps strength, and voluntary quadriceps activation over time. A one-way mixed model, ANOVA with repeated measures was performed in the control group to assess differences in corticomotor excitability over time. Post-hoc comparisons were performed when appropriate. Specific Aim 2: Separate, mixed model, linear regression analyses were performed in the control group (involved limb) to determine the effect that the neuromuscular quadriceps outcome measures assessed at baseline and 3 months post-ACLr, had on lower extremity knee functional outcome measures assessed at 6 months post-ACLr. Specific Aim 3: A 2x2x3 (group x limb x time) mixed model, ANOVA with repeated measures was performed to assess group differences between the involved limb and the uninvolved limb in isometric quadriceps strength, and voluntary quadriceps activation over time. A 2x3 (group x time) mixed model, ANOVA with repeated measures was performed to assess group differences in corticomotor excitability over time. Post-hoc comparisons were performed when appropriate. Results: Aim 1: Patients demonstrated lower quadriceps strength on their involved limb compared to their uninvolved limb at baseline, three months post-ACLr, and six months post-ACLr. Quadriceps strength progressively decreased in the involved limb of patients from baseline to 3 months post-ACLr, baseline to 6 months post-ACLr, and increased from 3 months to 6 months post-ACLr. Quadriceps strength was also decreased in the uninvolved limb of patients from baseline to 6 months post-ACLr. ). Irrespective of when it was assessed, voluntary quadriceps activation was higher in the involved limb of patients compared to their uninvolved limb. There were no changes in corticomotor excitability of the involved limb over time. Specific Aim 2: The quadriceps strength of patients at three months post-ACLr had a significant positive effect on their 6-month YBT-A performance KOOS score. ). Neither voluntary quadriceps activation or corticomotor excitability or AMT (at baseline or 3-month post-ACLr) had a significant effect on any of the 6-month lower extremity functional outcome measures. Specific Aim 3: Irrespective of limb or when it was assessed, quadriceps strength was higher in the control group compared to the Home-NMES group. Both groups demonstrated lower quadriceps strength on their involved limbs compared to their uninvolved limbs at baseline, three months post-ACLr, and six months post-ACLr. Quadriceps progressively decreased in the involved limbs of both groups from baseline to three months post-ACLr and baseline to six months post-ACLr, and increased from three months to six months post- ACLr. At baseline, voluntary quadriceps activation was higher in the involved limbs of both groups compared to their uninvolved limbs. There were no group differences or changes over time observed in the involved limb of both groups with corticomotor excitability. Conclusion: Although quadriceps weakness is more apparent in the involved limb of patients after ACLr, the quadriceps strength of their uninvolved limb was also affected. Clinicians are encouraged to not rely on a quadriceps strength limb symmetry index when making return-sport-decisions for their patients after recovering from ACLr. The quadriceps in the uninvolved limb of patients demonstrated more inhibition, which may explain the quadriceps strength deficits observed in the uninvolved limb of patients following ACLr. To reduce the risk of subsequent injury upon return-to-sport and protect against the development of knee OA, we recommend that clinicians incorporate bilateral interventions aimed at restoring quadriceps strength and disinhibiting the quadriceps. Intensive quadriceps strengthening should be performed in the early stages of ACLr rehabilitation, so that lower extremity function can be improved in patients later on. Lastly, the effectiveness of home-based NMES as a modality for restoring quadriceps strength and activation in patients after ACLr is inconclusive. Home-based NMES provides patients with the ability to receive higher doses of NMES to the quadriceps; but its effectiveness may be limited by low contraction intensities and poor treatment compliance in patients.

There is need for enhanced prevention and treatment methods to combat sedentary lifestyle, obesity, and chronic disease by investigating the impact of specific exercise modalities and dietary factors on human health. The purposes of this study were: 1) to assess self-selected and perceived exercise intensity during High-Intensity Functional Training (HIFT) between males and females and to determine variables that predict self-selected exercise intensity (%VO2max) and/or perceived intensity (RPE) and 2) to investigate the impact of obesity on skeletal muscle metabolism in response to lipid oversupply by analyzing the responses of genes linked with fatty acid oxidation and inflammation in lean and obese subjects. Males and females were recruited to complete a 15min HIFT circuit wearing a metabolic analyzer, reporting RPE during and after the exercise bout. Obese and lean females were recruited to provide skeletal muscle cell biopsies for harvesting cell cultures from which to measure change in gene expression after exposure to a high lipid treatment. The first study results demonstrate that females exercised at a significantly higher self-selected exercise intensity while also reporting a lower RPE (p < 0.05). The second study revealed differential gene expression response and pathway activation related to lipid metabolism and inflammation between the lean and obese. In conclusion, gender plays a significant role in the intensity self-selected and the RPE reported during HIFT, suggesting HIFT may be an optimal home-based modality for female clients. Additionally, the skeletal muscle metabolic and inflammatory gene expression of the lean and obese respond differently to a high fat exposure and may provide further evidence of mechanisms linking obesity to metabolic disease.

Lower extremity injuries are the most common sports related injury. Many steps have been taken to attempt to identify individuals who might be at a higher risk for sustaining a lower extremity injury. Resource and time intensive screening techniques have been used previously to attempt to identify such individuals. However these techniques have focused heavily on postural control and landing mechanics in athletes, no psychological measure has been used to identify individuals who might be at a higher risk of lower extremity injury. Self-efficacy of balance can be defined as how capable an individual feels he or she can balance in different scenarios. Research in the balance deficient population (elderly, post-stroke, knee osteoarthritis) has revealed that selfefficacy of balance is a quantifiable psychological component of balance related behavior. As previously stated, current screening techniques for lower extremity injuries do not incorporate psychological measures. Research suggests that psychological indicators of balance confidence are important to measure in conjunction with balance test performance to establish the relationship between the two constructs. Assessment of these factors is necessary to examine how psychological measures affect performance on tests used in clinical balance assessments. The objective of this dissertation was to develop the Self-Efficacy of Balance Scale (SEBS), a psychometrically sound self-efficacy of balance instrument for use in the young, active population. The relationship between selfefficacy of balance and self-reported measures of lower extremity function, and clinical and laboratory measures of balance were also examined in the young, active population. It was hypothesized that a valid, reliable, responsive tool could be created to accurately and precisely measure self-efficacy of balance in a young, active population. It addition, it was hypothesized that high levels of selfefficacy of balance would have a significant, positive relationship with selfreported measure of lower extremity function, and clinical and laboratory measure of balance. Results from the three studies brought about several interesting observations. Studies one, two, and three demonstrated evidence of a psychometrically sound instrument. This indicates that the SEBS is a valid, reliable, responsive self-efficacy of balance instrument when evaluating young, active individuals. Study three demonstrated the relationships between selfefficacy of balance and self-reported measures of function, and objective measures of balance. These relationships revealed that while lower extremity function and some measures of balance influence scores of the SEBS, they do not account for all of the variability of the SEBS. This finding further supports the claim that balance behavior is changing as function and postural control change. Therefore, future research should include investigation regarding the utility of the SEBS, as well as longitudinal studies to establish effectiveness of identifying individuals at a higher risk of sustaining a lower extremity injury.

Proximal stability, or the ability to stabilize and actively control the spine, pelvis and trunk, has been reported to influence sport performance. Traditional training practices for the proximal segments have had little success improving sport performance. The purpose of this dissertation was to investigate the effects a sport specific proximal stability training program can have on throwing velocity and measures of muscular endurance and power which target the proximal segments of the pelvis, spine and trunk. A stratified randomized clinical trial was implemented with a pre- to post-intervention design. Forty-six healthy, Division III collegiate female softball (n=17) and male baseball (n=29) players were randomly assigned to one of two training groups for 7 weeks; a traditional endurance training group (ET) (n=21) or a power stability training group (PS) (n=25). The primary outcome measures were the change in peak throwing velocity/Kg of body weight in mph. Mean throwing velocity, power outputs from a one-repetition maximum chop test and lift test (watts/Kg body weight), and muscular endurance plank tests. Student’s independent t-tests were used to compare differences between change scores of all dependent variables. Peak throwing velocity change scores were significantly faster (ET= .21 ±.55 mph, PS= 3.4 ±1.1 mph, p< .001) in the PS at post-intervention when compared to the ET group. Change scores were significantly greater in the PS group for mean throwing velocity, (ET= 1.1 ±1.6 mph vs. PS= 3.7 ±1.8 mph, p< .001), chop (watts), (ET= 20 ±78 watts vs. PS= 105 ±68 watts, p< .001), and lift, (ET= 49 ±62 watts vs. PS= 114 ±73 watts, p= .003). There were no change score differences for the side and prone plank endurance measures in seconds (p≥ .60). The PS group increased primary outcome measures over the ET program, indicating a more sport specific training regimen targeting the proximal segments is beneficial to both the power measures and throwing performance.