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The effect of dynamic resistance training on lipoprotein - lipid profiles27 October 2008 (has links)
M.Phil. / Numerous studies have demonstrated the favourable effects of aerobic training on blood lipid profiles. However, few studies have generated conclusive data on the effects of dynamic resistance training (DRT) on blood lipid profiles. In order to evaluate the effect of DRT on lipoprotein-lipid profiles, a group of 28 sedentary but healthy males (mean age 28 years and 7 months) were matched and randomly assigned into a control/non-exercising (n = 15) or an experimental (n = 13) group. To control for variations in lipoprotein-lipid profiles, the present investigation recorded dietary intake and smoking behaviour in an attempt to account for any changes in lipoprotein-lipid profiles over the eight-week period. The experimental group (EG) exercised using DRT for a period of eight weeks and was monitored for changes in lipoprotein-lipid profiles. The control group (CG) took part in no structured exercise throughout the eight-week period. The experimental training programme consisted of nine exercises (dumbbell (D/B) shoulder shrugs, D/B lateral shoulder raises, seated chest press, latissimus dorsi pulldowns, seated pulley rows, biceps curls, triceps extensions, crunchies and unilateral leg press). These exercises were performed at 60% of one repetition maximum (1-RM) and were performed three times per week on non-consecutive days. Serum was analyzed for total cholesterol (TC), triglycerides (TG), low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol (HDL-C). In addition to this, the TC: HDL-C and LDL-C: HDL-C ratios were calculated. The Independent t-Test and the Paired t-Test were utilized to determine the significance (at a 95% confidence level (p ¡Ü 0.05)) of the lipoprotein-lipid profile changes from pre- to post-test. These student t-Tests demonstrated no statistically significant changes in TC, TG, LDL-C, HDL-C, TC: HDL-C ratios and LDL-C: HDL-C ratios in the EG. However, the present investigation did demonstrate the following changes: a 0.50% decrease in TC, a 1.74% increase in TG, a 2.95% decrease in LDL-C, a 4.61% increase in HDL-C, a 4.12% decrease in the TC: HDL-C ratio and a 5.96% decrease in the LDL-C: HDL-C ratio. The lack of statistically significant changes in the individual lipoprotein-lipid parameters could not have been affected by diet, cigarettes smoked daily, aerobic fitness and/or body mass, since these parameters did not change significantly from pre- to post-test. Specifically, both the EG and CG demonstrated no statistically significant changes in intake in total calories consumed, carbohydrates, proteins, fats (monounsaturated, polyunsaturated and saturated fatty acids), cholesterol and fibre. Although the present investigation findings suggest that this study¡¯s eight-week combination of dose, workload, number of repetitions and order and number of exercises may not have been sufficient to elicit significant improvements in lipoprotein-lipid parameters in this population of sedentary but healthy males, it is the opinion of the author that DRT should be included with aerobic modes of exercise. DRT should be used in conjunction with aerobic modes of exercise for its additional benefits. Such additional benefits include inter alia: increased strength, increased lean tissue mass, increased maintenance of metabolically active tissue in the elderly and increased muscle control. / Prof. J.M. Loots Mr. L. Lategan
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Acute Effects of Resistance Exercise Intensity in a Depressed HIV Sample: The Exercise for People Who Are Immunocompromised (EPIC) StudyNosrat, Sanaz January 2018 (has links)
Introduction: In the US, Black/African Americans comprise the largest proportion of People Living with HIV (PLWH). Depressive symptoms and fatigue are highly prevalent among PLWH. Depressive symptoms are linked to progression of HIV disease, and fatigue is linked to severity of depressive symptoms. Resistance exercise is known to have psychological benefits in non-HIV depressed populations, and these benefits are hypothesized to be intensity-dependent. That is, moderate intensity exercise seems to stimulate better psychological outcomes compared to other exercise intensities. To date, no study has examined the acute psychological effects of resistance exercise intensity with depressed PLWH. Purpose: To test the acute effects of resistance exercise intensity on affect, perceived activation, and perceived distress among sedentary Black/African American PLWH who experience depressive symptoms. Methods: Twenty-five men and 17 women ages 24-66 (47.5±11.2) with a Center for Epidemiologic Studies Depression Scale score of ≥10 completed a battery of questionnaires and 10-repetition maximum (10-RM) muscular strength tests. Participants were randomized into a moderate intensity resistance exercise group (i.e., 70% of 10-RM), n=21, or vigorous intensity resistance exercise group (i.e., 100% of 10-RM), n=21. Both groups completed 3 sets of 10 repetitions for 5 exercises at the assigned intensity. Exercises include squat, chest press, lat pull-down, dumbbell shoulder press, and dumbbell biceps curl. Affect, perceived activation, and perceived distress were measured with the Feeling Scale, Felt Arousal Scale, and Subjective Units of Distress Scale, respectively. Measures were administered at PRE, MID, POST, at 15-minute DELAY, and at 30-minute DELAY. Changes were analyzed using repeated measures ANOVA, with Bonferroni adjustments for post-hoc analyses. Results: There were significant Time x Group interactions for affect (F=2.6, p=0.03, η2=0.1), and perceived distress (F=5.5, p<0.01, η2=0.1), and a main effect of Time for perceived activation (F=16.2, p<0.001, η2=0.3). In the moderate intensity group, affect improved PRE to POST (t=3.2, p<0.01, d=0.7), PRE to DELAY 15 (t=4.1, p<0.01, d=0.9), and PRE to DELAY 30 (t=4.1, p<0.001, d=0.7). In addition, perceived distress was reduced from PRE to MID (t=4.2, p<0.001, d=0.9), PRE to POST (t=5.5, p<0.001, d=1.2), PRE to DELAY 15 (t=5.6, p<0.001, d=1.2), and PRE to DELAY 30 (t=6.7, p<0.001, d=1.5). In the vigorous intensity group, affect declined PRE to MID (t=2.9, p<0.01, d=-0.6), while perceived distress improved PRE to DELAY 15 (t=4.8, p<0.001, d=1.0) and PRE to DELAY 30 (t=3.5, p<0.01, d=0.7). Perceived activation increased in both groups similarly PRE to MID (t=5.1, p<0.01, d=1.5), and PRE to POST (t=6.1, p<0.001, d=1.8). Conclusions: Results suggest that an acute bout of moderate intensity resistance exercise is more effective than vigorous intensity resistance exercise in improving affect, increasing energy, and reducing distress in depressed Black/African American PLWH. However, vigorous intensity resistance exercise also appears to have distress-reducing benefits, but this appears to only occur after exercise. These findings should be considered when prescribing exercise for depressive symptom management in this population.
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Investigations of the neuromuscular response during and following elite maximum strength and power type resistance exerciseBrandon, Raphael January 2011 (has links)
The thesis aimed to analyse the acute neuromuscular (NM) response during and following maximum strength and power training methods. The primary aim of study one was to establish the reliability of biomechanical and surface electromyographic (sEMG) measurements during barbell squat exercise. This would enable the subsequent studies to precisely assess muscle activity and mechanical power during barbell resistance exercise sessions. Nine male well-trained subjects performed squat exercise on three separate trial days. Each trial comprised one set of squat at 50, 75 and 100% of 3RM load. Synchronous recordings of knee joint kinematics from a flexible electrogoniometer, barbell displacement from a single linear position transducer and quadriceps sEMG amplitude were made. The mean maximum knee angle during squat was recorded at each load, and the overall inter-trial coefficient of variation (CV) was 5.5%. Mean concentric repetition power was processed from displacement data and derived into force and velocity values. The overall inter-trial CV for mean power was found to be 8.4%. The raw sEMG signal was processed into root mean square (RMS) amplitude and normalised to values taken from pre-trial knee extension maximum voluntary contractions (MVC). RMS amplitude was processed for the whole concentric phase and a 200 ms time interval at a knee angle of 70°, which matched the knee angle used during MVC. Inter-trial CV for RMS amplitude from the concentric phase and 70° knee angle were 7.2% and 16.4% respectively. There were no differences in RMS amplitude, maximum knee angle or mean power across trial days. It was concluded there was acceptable reliability for all three measurements (CV < 10%), if RMS amplitude was processed from the concentric phase. Based upon the measurement reliability, the analysis system was considered suitable for monitoring power and sEMG during barbell exercise. The second study aimed to establish the reliability of muscle fibre conduction velocity (MFCV) measurements during barbell squat. This was of interest, as MFCV may provide useful information of NM recruitment and fatigue processes during resistance exercise. The study was also used as a preliminary investigation of MFCV response, in comparison to RMS amplitude, to increasing fatigue and load during squat exercise. Nine well-trained male subjects performed a series of exercises on two separate trial days. Each trial comprised isometric knee extensions at 50, 75 and 100% of MVC force, followed by barbell squats at 50, 75 and 100% of 3RM, and then a maximal bout of squat jumps at 50% 3RM load, performed until failure. sEMG measurements were recorded from a four-electrode array, secured upon the vastus lateralis. Normalised RMS amplitude was processed as above, and MFCV was processed from the inter-electrode distance and time delay between two double differentiated and correlated signals, using bespoke software. The overall value of MFCV during squat was 5.8 m.s-1. The inter-trial CV for MFCV was 9.6% during squat and 12.1% during squat jump. Based upon acceptable reliability of 10%, MFCV measurements from barbell squats were considered reliable. As expected, MFCV significantly increased with each knee extension force level (4.7 ± 1.4, 5.6 ± 1.5 and 6.2 ± 1.8 m.s-1) (p<0.01), along with RMS amplitude (p<0.0001). No differences in MFCV were found between squat loads, whilst RMS amplitude significantly increased with load (p<0.0001). Power (1920 ± 143 versus 1407 ± 254 W) and MFCV (5.7 ± 1.4 versus 4.6 ± 1.0 m.s-1) significant decreased (p<0.001) from the start to the end of the squat jump trial, with RMS amplitude unchanged. Therefore, MFCV altered with increasing fatigue, but not load, during dynamic squat exercise. It was concluded that MFCV provides useful and reliable data for acute fatigue investigations of barbell resistance exercise, in addition to sEMG amplitude measures. The following three investigations compared NM responses during and following maximum strength and power type resistance exercise sessions with different exercises, loads and movement speeds. The sessions were designed to represent elite athlete training practices, to help inform the optimisation of resistance exercise programmes. The first of these studies aimed to compare NM response to a typical maximum strength session performed with barbell squat or deadlift exercise. The purpose was to assess if technical differences between the exercises, influenced the acute NM response. Nine elite trained weightlifters performed the trial sessions of five sets of five repetitions on separate days. Normalised RMS amplitude, MFCV and power was continually measured during exercise repetitions, using the methods established above. NM function was assessed pre- and post- sessions using MVC force, central activation ratio (CAR) from superimposed stimulation during MVC, and jump performance (CMJ). The exercises were performed with subjectively matched load levels, corresponding to active muscle RPE = 17 (Borg scale), and also with controlled lifting speed. However, the squat load was lowered and raised upon the lifter’s back, whilst deadlift load was grasped in the hands, raised from the floor and then dropped. Repetition mean power was unchanged within and across sets of both sessions. Repetition RMS amplitude significantly increased (p<0.001) within sets of squat and deadlift, whilst a significant interaction between sessions and set (p<0.001) demonstrated RMS increased more during squat. Furthermore, a significant reduction in repetition MFCV was found within sets of squat (p = 0.034), but not deadlift. This suggests that motor unit activation increased during both exercises, as a response to the task of maintaining power during repetitions of whole body lifting. However, acute fatigue within squat sets led to additional increased activation as a NM compensation strategy. No pre- versus post- session differences were found for MVC, CAR or CMJ; suggesting minimal change in NM function occurred following five sets of maximum strength type resistance exercise, in well-trained subjects. The primary aim of the second study was to compare NM response and 24-hour recovery following barbell exercise maximum strength and power type sessions. The purpose was to specifically establish the degree and nature of NM response, as previous findings were unclear and barbell exercise sessions of this type have not been compared. 10 elite sprint athletes performed sessions comprising squat, split squat and push press, with four sets x repetitions per exercise. The maximum strength session exercises involved loads corresponding to active muscle RPE = 17 (Borg scale) and metronome controlled movements. The power session exercises used 30% of the maximum strength barbell load, performed as fast as possible. Repetition sEMG and power was monitored throughout each session, as above. NM function was assessed, pre-, post- and 24-hour post- each session, using the same tests as above. However, evoked peak twitch force (Pt) was also included to the pre- and post- assessments. Overall, the maximum strength session involved greater total work (p = 0.008), but lower mean power during exercise repetitions (p<0.001) in comparison to the power session. MVC and Pt force values both significantly decreased (p<0.05) pre- versus post- both sessions. However, MVC reduced more following maximum strength session (p<0.01). CAR and CMJ were unchanged post-both sessions and no differences were found between pre and 24-hour post session NM tests. The decreased Pt but not CAR findings, suggest peripheral fatigue explains the reduced force generation capacity following maximum strength and power sessions, contrary to previous resistance exercise session findings. Up to 24-hours may be required to recover force generation capacity following this volume of resistance exercise.
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Progressive moderate to high resistance training (PMHRT) by lower limbstrengthening in ambulatory elderly persons with risk of falls林桂儀, Lam, Kwei-yee. January 2005 (has links)
published_or_final_version / Medical Sciences / Master / Master of Medical Sciences
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Effects of a modified straight leg raise on strength and muscle activity of the vastus medialis oblique in patients with patellofemoral malalignmentWilson, Timm January 1993 (has links)
The purpose of this study was to determine the effectiveness of a modified sitting position straight leg raise on vastus medialis oblique (VMO) strength and EMG activity as compared to a traditional straight leg raise. A total of twenty-three subjects were recruited for this study. The subjects were randomly assigned to one of the following groups: (group I) modified straight leg raise (MSLR), and (group II) straight leg raise (SLR). The exercise program was three weeks long. University procedures for the protection of human subjects were followed. The subjects began with a 5 minute warm-up on a Cybex stationary bike set at 90 revolutions / minute. The subject then had electrodes placed on the Vastus Lateralis (VL) and Vastus Medialis Oblique (VMO). A Macintosh computer was used to record the EMG data. The subject then performed a standard Cybex test for knee flexion and extension. The Cybex dynamometer was placed at the knee joint line, the chair back tilt was at 85 degrees, the hip, chest, and thigh restraints were all fastened. The subjects in group I (Modified sitting SLR) and II (SLR) then returned the next day for their first rehabilitation lesson. Each subject group then participated in their respected exercise program for a total of three weeks. After three weeks of rehabilitation, the subjects retested using the same procedures followed in the pretest. A two tailed t-test was used to determine significance of the difference between means of the two groups. No significant differences were found between the two groups. / School of Physical Education
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Effects of a traditional and modified straight straight leg raise on EMG characteristicsBasey, Adriana L. January 1997 (has links)
The purpose of this study was to determine the vastus medialis oblique muscular electromyographical (EMG) activity during two therapeutic exercises: the modified straight leg raise and the traditional straight leg raise. Two subject groups of 10 subjects each, one with anterior knee pain (PHY) and the other group with no history of patellofemoral pathology (NORM), performed the traditional straight leg raise (SLR) and a modified straight leg raise with external hip rotation (MOD). Each subject performed an isometric maximum voluntary contraction and three trials of each of the two therapeutic exercises. The EMG variables analyzed were the percent of the maximum voluntary contraction for each muscle, vastus medialis oblique, vastus lateralis, and rectus femoris: the percent of the maximum voluntary contraction of the ratio between the vastus medialis oblique and the vastus lateralis; the percent of the maximum voluntary contraction for the integrated EMG for each muscle; and the percent of the maximum voluntary contraction for the root mean square for each muscle. The statistical analysis was conducted with two-way analysis of variance procedures. The statistical analysis revealed no significant differences; however, the data appeared to illustrate a trend toward more electromyographical activity in the vastus medialis oblique in the PHY subject group during the MOD therapeutic exercise. This suggests that the MOD therapeutic exercise may be able to isolate the vastus medialis oblique muscle in persons with anterior knee pain and allow them to regain strength and normal function earlier than with the use of the SLR therapeutic exercise. / School of Physical Education
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The influence of force production and eccentric exercise on growth hormoneKim, Junghoon January 1997 (has links)
The main purpose of this study was to investigate the relationship between human growth hormone (hGH) and two separate components of resistance exercise. Eight non-weight-trained subjects (23.33 ± 0.3 yrs) performed three force production trials (FPT), at different concentric workloads, and an 120% eccentric exercise trial (EET) on the Cybex 6000. Blood samples (3 mls) were taken pre- and post-exercise and analyzed for lactate, creatine kinase (CK) and hGH. Electromyographic (EMG) activity of the quadriceps muscle was recorded during each trial. The mean peak torque produced during the FPTs increased as work intensity increased but was the highest in the EET. The data for total work showed a proportional relationship with the intensity of the three concentric work loads but not the 120% EET. EMG activity of vastus medialis (VM) and rectus femoris (RF) measured during EET was 26% less than RF of 50% and 15% less than VL of 70% in FPT, respectively. The highest hormonal response occurred following the 120% EET. The hormonal response following the FPTs was highest in the 90% FPT with the two lower work intensity trials (50 and 70%) showing no clear hormonal response. Although the hGH response was the highest in the 120% EET, the post-exercise lactic acid levels in EET were 24% less than that of the 90% FPT. Creatine kinase (CK) activity was significantly elevated 36 hours after the last bout of EET which suggests that the eccentric exercise resulted in muscle damage. The results from concentric trials showed that muscle force generation, EMG, and lactic acid of the three different concentric trials were well correlated to the pattern of hGH secretion. However, only peak torque was consistent with the hGH response of the EET. The highest peak torque and hGH levels were achieved with eccentric exercise. The highest levels of fatigue, as a result of the combination of longer exercise time and overloading of the muscle during EET, may explain the higher hGH output. The muscle damage caused by the eccentric trial was enough to induce delayed onset of muscle soreness and may be the stimulus for the higher hGH output. The hGH response may facilitate repair of the muscular damage induced by eccentric exercise by promoting protein synthesis. / School of Physical Education
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Effects of progressive resistance training on skeletal muscle protein isoform adaptations in elderly menWilliamson, David L. January 1999 (has links)
Progressive resistance training (PRT) in the elderly has commonly used ATPase histochemistry to evaluate fiber type changes, but evidence shows there are myosin heavy chain (MHC) hybrids in aging muscle that cannot be classified by histochemistry. The purpose of this study was to assess the MHC and whole muscle alterations following a 12-week PRT protocol. Seven healthy men (age=74.0±4.7, weight=74.6±13.5kg) underwent testing for 1-repetition maximum (1-RM), whole muscle (thigh) crosssectional area (CSA) by computed tomography, and a needle muscle biopsy from the vastus lateralis for analysis of MHC, pre- and post-training. The PRT consisted of 2 sets of 10 repetitions, and a third set to volitional exhaustion at 80% 1-RM, 3 days per week for 12 weeks. Muscle ATPase histochemistry analysis for distribution did not significantly differ following training. Muscle samples were freeze dried and dissected for MHC analysis (sodium dodecyl sulfate-polyacrylamide gel electrophoresis (5% gel) and silver stained; 224.0±11.2 and 213.0±8.1 fibers/subject pre-/post-training; total fibers analyzed=3059). MHC analysis demonstrated significant increases in MHC I proportion (10.4%; P<0.05), and significant decreases in MHC UIIa (9.0%; P<0.05), UIIa/x (0.9%; P<0.05), and IIa/x (8.9%; P<0.05) isofroms, along with no change in the MHC Ila and IIx isoforms, pre- versus post-training. In addition, 1-RM (51.9%; P<0.05) and CSA (5.9%; P<0.05) increased from pre- to post-testing. This data supports previous whole muscle changes, more important, is the increase in MHC I and decrease in MHC I/IIa, I/IIa/IIx, and IIa/x hybrids. The myosin light chain 3f (MLC3f) to MLC 2 ratio did not change with the PRT in either the MHC I or MHC IIa isoforms, although there was a significantly greater amount of MLC 3f in the MHC Ila versus the MHC I fibers (p<0.05), pre- and post-training. The myosin isofrom data provides support that aging muscle has the plasticity to adapt in a manner unlike that of young muscle. / School of Physical Education
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Influence of COX-inhibitors on myofiber hypertrophy and capillarization in response to resistance exercise in older individuals / Influence of COX inhibitors on myofiber hypertrophy and capillarization in response to resistance exercise in older individuals / Influence of cyclooxygenase-inhibitors on myofiber hypertrophy and capillarization in response to resistance exercise in older individualsBrower, Brooke E. 20 July 2013 (has links)
Access to abstract permanently restricted to Ball State community only. / School of Physical Education, Sport, and Exercise Science
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The effect of a cyclooxygenase-2 inhibitor on human mixed muscle protein synthesis after acute resistance exerciseBurd, Nicholas A. January 2007 (has links)
We have previously shown that non-specific blockade of the cyclooxygenase (COX) enzymes in skeletal muscle eliminates the normal increase in muscle protein synthesis following resistance exercise. The current study tested the hypothesis that this COX-mediated increase in postexercise muscle protein synthesis is specifically regulated by the COX-2 isoform. Sixteen males (23 ± 1 yr, 177 ± 2 cm, 81.5 ± 3.4 kg) were randomly assigned to one of two groups that received three doses of either a specific COX-2 inhibitor (celecoxib; 200 mg per dose, 600 mg total) or a placebo during the 24 hours following a single bout of resistance exercise with the knee extensors. Skeletal muscle fractional synthesis rate (FSR) was measured at rest and 24 hours postexercise using a primed constant infusion of [2H5]phenylalanine coupled with muscle biopsies of the vastus lateralis. Mixed muscle FSR was increased following exercise to a greater extent (206%, P<0.05) in the COX-2 group (0.052 ± 0.014 %Ih) as compared with the placebo group (0.017 ± 0.007 %Ih). These results suggest that the specific inhibition of the COX-2 isoform in human skeletal muscle causes a compensatory response in muscle protein synthesis. These data also highlight the involvement of the cyclooxygenase pathways in the regulation of muscle protein synthesis following resistance exercise. / School of Physical Education, Sport, and Exercise Science
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