Two studies were conducted to determine if Hsp70 is able to protect human skeletal muscle from muscle mechanical damage and alterations in SERCA activity associated with prolonged concentric exercise. In the first study, one-legged isometric knee extension exercise at 40% MVC and a duty cycle of 50% (5 sec contraction followed by 5 sec of relaxation) was used to induce a heat shock response in one leg only. Participants were followed over six recovery days to determine the time course of Hsp70 induction and decay. Results showed fiber type specific increases in Hsp70 that persisted in one leg only throughout six days of recovery. These increases in Hsp70 occurred with only transient changes in Ca2+ uptake and muscular force. With the exception of minor decreases in low frequency force, there were no apparent reductions in muscular force or SERCA activity by the third recovery day. Therefore an exercise protocol was established which was able to induce a heat shock response with only minor alterations in muscle mechanical function and SERCA activity. In the second study, the same isometric exercise was employed, however, on the day corresponding to recovery day 3 in the first study, participants were asked to complete a one hour cycling protocol at 70% VO2 max. The goal was to cause similar one-legged increases in Hsp70 as the first study and to then challenge SERCA activity and muscular force in the presence of elevated Hsp70 by using cycling exercise. Results showed cycling induced reductions in maximal Ca2+ ATPase activity, muscular force, rates of muscle relaxation, and rates of muscle force development were attenuated by the preconditioning (isometric) exercise. These studies confirm the idea that preconditioning exercise is able to attenuate subsequent exercise induced insults to SERCA activity and muscular force, likely through an Hsp70 mediated mechanism.

Early strength increase with training is normally attributed to neural adaptations but recent evidence suggests that muscle hypertrophy occurs earlier than previously thought. The purpose of this study was to examine the time course of adaptation through 20 days of training and 5 days of detraining. Twenty-two untrained subjects trained one arm every 2nd day for 20 days. Subjects performed isokinetic eccentric biceps training at 90°/s (6 sets of 8 reps). Muscle thickness (reported in cm) via ultrasound, strength (reported in Nm) and muscle activation (electromyography) were measured before, during and after training (9 time points). Muscle thickness increased after 8 days of training (3.66±0.11 to 3.90±0.12; p<0.05) and remained above baseline until the end of training (3.97±0.12). After 5 days of detraining muscle thickness decreased (3.97±0.12 vs. 3.85±0.11; p<0.05), but remained higher than baseline (p<0.05). Muscle thickness did not change significantly in the untrained arm at any time point. Strength in the trained arm decreased after 8 days of training (65.6±4.1 to 57.5±3.5; p<0.05) and remained suppressed throughout the study. Muscle activation amplitude increased after 14 days of training (p<0.05) and remained elevated throughout the study. In conclusion, biceps muscle thickness increases very rapidly with frequent intense eccentric training although this type of training appears to impair strength. These findings provide additional evidence that muscle hypertrophy may occur much faster than has been generally accepted.

Imaging based muscle density (MD) is associated with poor lower extremity performance, the development of mobility impairments, frailty, and hip fracture. These associations are all related to falls, yet no studies have investigated MD in community dwelling fallers. The primary objective of this study was to determine whether lower leg MD differed between community dwelling elderly women who do and do not report falls. The secondary objective was to determine if lower leg muscle cross sectional area (MCSA), timed up & go (TUG) test, and relative grip strength (RGS; as a ratio to body mass) differed between fallers and non-fallers. Women (N = 135), 60 years or older (mean age 74.1, SD 7.6) were recruited from a random sample of Saskatoon residents. Fallers (n = 36) and Non-fallers (n = 99) were grouped based on 12-month retrospective falls survey response. A peripheral quantitative computed tomography (pQCT) scan of the non-dominant lower leg was acquired to determine MD and MCSA. Participant age, height, weight, TUG test result and RGS were recorded. Between-group differences in mean age, body mass index (BMI), MD, MCSA, TUG and RGS were compared using independent t-tests (P < 0.05). MD and TUG results were transformed to meet the assumption of normality for parametric analysis. Age, BMI, MCSA and RGS did not differ (P > 0.5). Fallers had 3.2% lower MD (P = 0.01) and 15.1% slower TUG scores (P = 0.02), than non-fallers. Muscle density may serve as a physiological marker for the assessment of muscular health and fall risk in community dwelling elderly women.

Throughout the performance horse industry, the occurance of various muscle disorders is common and can be detrimental to the performance and longevity of equine athletes. Research has revealed effects of diet manipulation, exercise, and electrolyte supplementation on the symptoms and occurrence of disorders like exertional rhabdomyolysis (ER). However, there has been no investigation on effects of Mg on muscle function in horses during exercise. Six Quarter Horse mares were used to study the effects of varying levels of Mg on indices of muscular dysfunction during a standardized exercise test (SET) on a highspeed treadmill. Three rations were used over three 28 d periods: control (Trt 1), low Mg (Trt 2), and high Mg (Trt 3). A baseline SET was conducted prior to day 0 (Trt 0). Blood samples were taken during the SET at rest, immediately post, 1 h, 6 h, and 24 h post exercise for analyses of serum muscle enzymes and Mg concentrations. Heart rates (HR), respiration rates (RR), and rectal temperatures (RT) also were documented. No effect of Trt was observed on HR or RR at any point throughout the SET. Resting RT?s were lowest in Trt 0 (P<0.05). There was no Trt effect on blood lactate (LA) during the SET; however, blood glucose (GLU) at rest in Trt 2 was lower than Trt 0 (P<0.05). Treatment had an effect on both resting serum creatine phosphokinase (CK), as Trt 3 was higher than Trt 0, and the change in CK from rest to 24 h post SET, where Trt 1 exhibited the greatest increase in CK concentration (P<0.05). Serum aspartate aminotransferase (AST) and lactate dehydrogenase (LDH) were not affected by Trt (P>0.05). Serum alkaline phosphatase (AP) at rest and 6 h post exercise was lower in Trt 2 than in Trt 3 (P<0.05). Additionally, serum P was lowest at rest in Trt 0 and highest 6 h post exercise in Trt 3, also varying within each Trt. Average daily intake (ADI) of Mg was higher in Trt 1 and 3 than in Trt 2 (P<0.05). Finally, at rest, immediately post and 24 h post exercise, serum Mg was highest in Trt 3 (P<0.05). Results suggest there is an effect of dietary Mg on serum muscle enzyme and Mg concentrations and potentially, overall performance in the equine athlete.

Low frequency mechanical vibrations (<100 Hz) are naturally generated by skeletal muscles during voluntary contractions. Recording of these vibrations at the muscle surface are called surface mechanomyograms (S-MMGs). In this study, S-MMGs were recorded over a 3 x 5 grid of skin mounted accelerometers on the biceps brachii muscle during submaximal voluntary isometric contractions with the arm in a pronated position for ten healthy and young male subjects with no overt sign of neuromuscular diseases. For a given pair of accelerometers, the spatial coherence of S-MMG is a measure of the similarity of the S-MMG signals propagating between those two sensors. Two common techniques to estimate the spatial coherence for narrowband S-MMG signals, namely the magnitude squared coherence function and the maximum of the time-domain cross-correlation function, were found to yield similar results. In particular, high spatial coherence values were measured for sensor pairs aligned along the proximal to distal ends of the biceps, i.e. the longitudinal direction. On the other hand, the spatial coherence values for sensor pairs oriented perpendicular to the muscle fiber, i.e. along the transverse direction, were found to be significantly lower. This finding indicates that coherent S-MMGs were mainly propagating along the muscle fibers direction (longitudinal) of the biceps brachii within a frequency band varying between 10Hz to 50Hz. Additionally, the spatial coherence of S-MMGs along the longitudinal direction was found to decrease with increasing frequency and increasing sensor separation distance and to increase with contraction level varying between 20% to 60% of the maximum contraction level.

Thesis (Ph. D.)--University of Missouri--Columbia, 2000. / Typescript. Vita. Includes bibliographical references (leaves 199-207). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri--Columbia, 2003. / "May 2003." Typescript. Vita. Includes bibliographical references (leaves 102-113).

Lic.-avh. (sammanfattning) Stockholm : Karolinska institutet, 2008. / Härtill 3 uppsatser.

Thesis (Ph. D.)--York University, 1999. Graduate Programme in Biology. / Typescript. Includes bibliographical references. Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://wwwlib.umi.com/cr/yorku/fullcit?pNQ56221.

Thesis (Ph. D.)--University of Washington, 2002. / Vita. Includes bibliographical references (leaves 70-92).