The purpose of this study was to compare the efficacy of two dose levels of L-Alanyl-LGlutamine in a commercially available sports drink to the sports drink only on time to exhaustion, neuromuscular fatigue and physiological measures during prolonged endurance exercise. Twelve endurance-trained males (23.5±3.7 yrs; 175.5±5.4 cm; 70.7±7.6 kg) performed four trials, each consisting of 1 hr treadmill runs at 75% of VO2peak followed by a run to exhaustion at 90% of VO2peak. The trials differed in type of hydration. One trial consisted of no hydration (NHY), another required ingestion of only a sports drink (ET), and two trials required ingestion of a low dose (LD) (300 mg∙500 ml-1) and high dose (HD) of L-Alanyl-L-Glutamine (1 g∙500 ml-1) mixed in the sports drink. During the fluid ingestion trials 250 ml were consumed every 15 min. Plasma glutamine, glucose, electrolytes, and osmolality were measured prior to the run (PRE), and at 30, 45, and 60 min. VO2, RQ, and HR were measured every 15 min and surface electromyography (EMG) of the vastus lateralis and rectus femoris were measured every 10 min during the 1 hr run. Time to exhaustion was significantly longer during the LD and HD trials compared with NHY. Plasma glutamine concentrations were significantly elevated at 45 min in LD and HD trials, and remained elevated at 60 min during HD. Sodium concentrations increased with the beginning of exercise and remained stable for the duration of the 1 hr run. At 60 min plasma sodium was significantly lower in all trials compared with NHY. The results from this study indicated that ingestion of the alanine-glutamine dipeptide at either the low or high dose significantly improved time to exhaustion during high intensity exercise compared to a no hydration trial. These differences were not noted between ET and NHY.

Knee osteoarthritis (OA) is a progressive disease that ultimately requires patients to receive a total knee arthroplasty (TKA) to replace the damaged structures within the knee with an artificial joint. Surgeons have many options when selecting an appropriate implant. Patients want a TKA that feels 'normal' and allows them to perform most activities without pain, stiffness, and other residual symptoms. However, 20% of patients remain unsatisfied with their surgery, regardless. This thesis aimed to examine the effect of implant selection during TKA on knee biomechanical function during various ADLs. Several gaps were identified within the review of literature: 1) patient-reported outcome measures cannot differentiate between medial ball and socket (MBS) and posterior stabilized (PS) implants, 2) most biomechanical studies were performed only in postoperative patients, and 3) studies that compared MBS and PS implants were primarily focused on level walking conditions, and overlooked tasks that placed more demand on the knee joint. Twenty-eight individuals with severe knee OA were randomized to receive either an MBS (n=14) or PS implant. They completed a biomechanical assessment within one month and one year after TKA and were compared to 14 controls of similar age, sex, and body mass index. They performed a variety of tasks which explored three main areas: 1) examine the alterations in gait variability among individuals with OA following a TKA procedure using either a PS or MBS implant; 2) enhance the understanding of the post-operative effects of TKA with either MBS and PS implants on knee biomechanics and muscle activities during level walking, as well as more demanding tasks such as descending a ramp or staircase; 3) simulate the dynamic knee joint loads in post-operative TKA patients with either PS or MBS implants during closed-chain, bilateral tasks such as sit-to-stand. Initially, a series of studies were performed to develop a new test called waveform-level variance inequality test (eqvartest), which had not been previously utilized in the literature. This test was used to identify discrepancies in gait variability pre and post-TKA in the gait cycle. Following TKA, patients showed decreased variability in knee moment and power at single-limb support. Neither the MBS nor PS implant provided the same level of variability as the control group, demonstrating reduced knee joint stability. The MBS group had a gait pattern closer to the control group during level walking, whereas the PS group walked with a stiffer knee. However, during more demanding ADLs, the differences were less apparent. During ramp descent, knee joint stability issues became prominent as MBS and PS groups adopted a 'cautious gait pattern,' widening their base of support and stiffening their knee to reduce loading. During stair descent, the MBS implant provided increased stability as it required less muscle activity than the PS, requiring greater hamstring muscle activation. During sit-to-stand, MBS and PS groups favoured their non-operated knee as they had reduced total vertical, medial, and lateral KCF on their operated knee compared to their non-operated side. This may be due to compensatory strategies developed through the progression of knee OA and may increase the risk of developing knee OA on the non-operated limb. The outcomes of this thesis can assist clinicians in selecting the most appropriate implant for their patients and guide them in designing rehabilitation programs that can enhance patient function following TKA.

Lifting weights, moving large, heavy objects, or maintaining same posture for extended periods of time exposes workers, mostly in the industrial sector, to pressure on their lower backs, which can have a significant negative impact and result in a variety of musculoskeletal problems and discomfort. The use of an exoskeleton can help to protect workers against lower back injuries of this kind. Past studies have been conducted to study the impact of the exoskeleton on upper body and legs with different exoskeleton, while this study will be an additional study which covers the impact on the most essential and used part of human body i.e., lower back (Thoracolumbar fascia). Workers working in the industrial sectors face more health issues and disabilities because of working on uneven surfaces, under uncomfortable positions like bending, squatting, twisting, and stretching which might impose adverse impact on lower back resulting in a higher number of sick leave.  If more people are impacted by disorders caused by lower back pain, the lesser would be the healthy workers available for work leading to shortage of competent workers in the industry. Back discomfort can affect a person's capacity to work; in fact, it's one of the most prevalent causes of temporary or permanent exclusion from the labor force when it comes to sick leave. The total estimated societal costs of low back pain in Sweden in 2001 was €1860 million, which included all medical expenditures as well as lost productivity as a result of the ailment. Estimates place the total economic cost of LBP in Sweden at €740 million, or €78 per person, for all episodes that started in 2011. [1].  This research study used a passive exoskeleton, namely “BackX”, developed by SUITX Inc. and its impact was measured on the body’s lower back in deep squatting and virtual chair position. Electromyography (EMG) sensors were deployed onto the participant's body as a measuring gadget. The investigations also examined the body muscle data of the various volunteers as recorded by the EMG sensors embedded in the thoracic-lumber fascia, a muscle in the lower back with and without exoskeleton.  The 3DSSPP model has also been used in this research to study the impact of force vs angle relation. It showed how much force was exerted on the human's lower back when lifting weights without wearing the exoskeleton.  In addition, using the proper data processing techniques, the signals from the acquired data will be filtered and processed. According to this study, it is possible to minimize skeletal muscle (Thoracolumbar fascia) activity by up to 60% by using these exoskeletons, which will improve the working conditions for the workforce by easing physical strain. The findings of this study will help small and medium enterprises (SMEs) spread the word regarding the advantages of exoskeletons, which will help to increase public awareness.

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The purpose of this study was to investigate the effects of differing goal strategies on subjective and physiological indices of workload across time. The sample consisted of 16 males and 24 females from undergraduate psychology classes at the University of Central Florida. Subjects were assigned to four goal conditions: time/accuracy, time, accuracy, and no goal, and asked to perform a computer-based decision making task comparing visual and semantic information. A trial consisted of a 15-minute baseline and three 5-minute task periods. Dependent variables included electromyopotential (EMG) measured in microvolts and a paper and pencil workload scale utilizing a Likert-type format and measuring three dimensions: general psychological stress (GPS) load, mental effort load, and time load. Results indicated that assigned goal strategy had no effect of the workload indices. Analyses of variance and trend analyses, however, revealed them EMG and mental effort load both increased from baseline to talk period 1 then decreased across time. This relationship was just the reverse for GPS load. In addition, time load decreased across time in a significant linear fashion. Zero-order correlational analyses were also performed using all dependent variables. EMG and time load were inversely related during task periods 1 and 2 whereas mental effort and GPS load were related only during task period 1. Results are discussed with reference to future research methodology in the area of workload assessment.

<p>The purpose of the thesis was to evaluate the neuromuscular control of shoulder muscles when performing concurrent shoulder and hand or elbow efforts in healthy and injured individuals. Of particular interest was the response of the supraspinatus and infraspinatus muscles to performing an additional hand task, such as gripping, while also performing different shoulder actions. Two studies were undertaken to provide the necessary groundwork for the subsequent two studies of this thesis. The first study investigated whether changes to shoulder muscle activity previously seen with gripping where the result of the novelty of using feedback to regulate grip force. This study found that changes in shoulder muscle activity with gripping are not diminished with repetition. The second study provided an improved method of normalizing electromyograms from dynamic contractions and was used in the subsequent studies of this thesis. Studies 3 and 4 of this thesis examined the response of shoulder muscles in healthy individuals during static sub-maximal efforts and maximal dynamic efforts in flexion and scapular planes with neutral and supinated forearm postures. Three conditions were tested in both studies: (i) no additional load, (ii) gripping to 30% of maximum and (iii) contracting the biceps to 30% of maximum. A prevailing theme found during sub-maximal contractions was individuality in neuromuscular recruitment strategies and precluded any significant effects of gripping or biceps contractions. During dynamic contractions, concurrent shoulder efforts with gripping and biceps contractions was found to significantly decrease deltoid, supraspinatus and infraspinatus muscle forces during flexion with supinated forearm posture. This thesis provided a thorough examination of shoulder electromyography in healthy individuals, improving our understanding of the neuromuscular control of the shoulder musculature. A common theme of this thesis was the individuality of neuromuscular strategies of the shoulder.</p> / Doctor of Science (PhD)