This thesis investigates the effect of acute isometric handgrip exercise on cognitive function in young healthy adults / Acute whole-body exercise transiently improves cognitive function which may be mediated by increased cerebral blood flow (CBF) and arousal. Interestingly, small muscle mass exercise, like isometric handgrip exercise (IHG) may stimulate the same physiological responses as whole body-exercise and improve cognitive function. However, these effects are poorly understood, and whether sex-based differences exist in the cognitive response to IHG is unknown. Therefore, the purpose of this study was to investigate whether acute IHG improves cognitive function in young healthy adults and examine potential sex differences in the cognitive response to IHG. We hypothesized that acute IHG would improve cognitive function compared to a control condition, and that females would have greater improvements in cognitive function due to a lower exercise pressor response. To test this, 30 participants (n=15 females, mean age=23.8±3.3 years;BMI=25.3±4.1 kg/m2) completed either IHG or a control condition in a randomized-crossover design separated by at least 2 days. IHG consisted of four sets of 2-min unilateral squeezing a handgrip dynamometer at 30% maximal voluntary contraction separated by 3-min of rest. The control condition watched a nature documentary for 20-min. Hemodynamics (systolic blood pressure, diastolic blood pressure, mean arterial pressure, and heart rate) were assessed throughout. Executive function, working memory, and processing speed were assessed via the 4-Choice, Corsi Block, and N-Back tests. Arousal was assessed using the Felt Arousal Scale (FAS). Middle cerebral artery blood velocity (MCAv) was assessed using transcranial Doppler ultrasound. Compared to the control condition, IHG significantly increased MAP (∆ 26 ± 17 mmHg; P<0.001), HR(∆ 18 ±13 bpm; P<0.001), MCAv (∆ 5.27 ± 19.4 cm/s; P<0.001), cerebrovascular resistance (∆ 0.71 ±0.69 mmHg/cm/s; P=0.003), and arousal (∆ 2 ± 2 FAS score; P<0.001). Cerebrovascular resistance was calculated as MAP/MCAv. Overall, despite increases in MCAv and arousal, there was no effect of IHG on cognitive performance, and no sex differences were observed in the cognitive response to IHG. These findings stand in opposition to emerging work and suggests that increased CBF and arousal via acute IHG are an insufficient stimulus to enhance cognitive function in young adults. Furthermore, there seems to be no moderating effect of biological sex on the cognitive response to acute IHG. / Thesis / Master of Science (MSc) / It is well known that whole-body exercise, such as running, swimming, or lifting weights, improves cognitive function. Cognitive function encompasses our ability to pay attention, remember new information, and make important decisions. We sought to investigate whether isometric handgrip exercise (IHG) could improve cognitive function in young adults, because it may be a new and accessible way to improve cognitive abilities. We also wanted to know if IHG had a different effect on cognitive function in females compared to males. To test cognitivefunction, participants played computer games that measured how their cognitive abilities were affected by IHG. In particular, we examined how IHG impacted a participant’s memory, decision making, and speed to completion. Our results show that IHG increased blood flow to the brain and made participants feel more alert compared to a control condition, however, IHG did not improve performance on the computer games. Males and females also did not differ in terms of their performance on the cognitive tests. Overall, a single session of IHG did not improve cognitive function in young adults. Although IHG did not improve cognitive function in young adults, it should be investigated in other individuals, such as older adults and people with hypertension, who may stand to gain more from IHG.

<p> Hypertension is a modifiable risk factor for cardiovascular disease. The current treatment options are drug therapy and lifestyle modifications. A promising lifestyle modification therapy for the management of hypertension is isometric exercise, as several studies have demonstrated that isometric handgrip (IHG) training reduces resting arterial blood pressure (ABP) (Peters et al., 2006; Taylor et al., 2003; Wiley et al., 1992). The purpose of the present investigation was two-fold: 1) to examine the effectiveness of IHG training in reducing resting ABP in newly diagnosed hypertensive patients, in comparison to matched controls receiving advice from a physician about lifestyle modifications; and 2) to examine markers of autonomic function, specifically, heart rate variability (HRV) to determine if changes in the autonomic nervous system (ANS) existed between the two groups of hypertensive adults.</p> <p> Resting blood pressure and heart rate were assessed with an automated acquisition system before, during and after the 6-week intervention period. Also, power spectral analysis of HRV was used to assess changes in modulation of the ANS. Participants in both groups (n=14) were given lifestyle modification recommendations regarding diet, exercise and stress reduction, while participants in the training group (n=8) also completed a bilateral IHG training protocol 3 times/week at 30% maximum voluntary contraction (MVC).</p> <p> Our results demonstrate that contrary to our hypothesis, isometric exercise in combination with lifestyle modification recommendations did not result in a reduction of resting ABP or change indices of HRV. Possible explanations for these results are that unlike previous IHG training, the present study was the first to use home-based training and the small sample size of this investigation would limit our ability to identify alterations in resting ABP or HRV.</p> / Thesis / Master of Science (MSc)

<p> Supervised isometric handgrip training (IHG) has been shown to lower blood pressure (BP) and therefore, may be an effective non-pharmacological treatment for hypertension. The present investigation examined the efficacy of unsupervised IHG to lower BP in patients who were recently diagnosed as hypertensive. Since the mechanisms responsible for attenuating BP remain unclear, this study also investigated the concurrent effects of IHG training on the autonomic nervous system (ANS) and arterial stiffness.</p> <p>Eight participants were randomized to the experimental group and the remaining six served as controls. Lifestyle modifications to lower BP were recommended for both groups. In addition, the experimental group completed IHG three times per week for six weeks. IHG consisted of four two-minute isometric contractions at 30% maximal voluntary contraction using alternate hands, each separated by a one-minute rest period. Pre- (PRE) and post-intervention (POST), BP was measured and the ANS was assessed by baroreceptor sensitivity (BRS) and both systolic and diastolic blood pressure variability (SBPV and DBPV) and arterial stiffness was evaluated by carotid-finger pulse wave velocity (PWV). All measures were assessed during a period of supine rest and during a 60° passive tilt.</p> <p> There were no significant changes in any BP measure from PRE to POST for either the experimental or control groups. There was a non-significant trend toward decreased heart rate (p = 0.065). BRS decreased from PRE to POST in both the experimental (10.7 ± 2.4 mm Hg to 9.7 ± 2.3 mm Hg) and control groups (8.6 ± 2.1 mm Hg to 7.6 ± 1.5 mm Hg), but there was no difference between groups. SBPV LF:HF was lower at POST than PRE in both experimental (6.8 ± 1.5 to 4.6 ± 1.1) and control (3.4 ± 1.9 to 2.3 ± 0.9), but there were no other differences in any other BPV variable. There were no significant changes in PWV.</p> <p> In conclusion, unsupervised IHG did not lower resting BP in newly diagnosed hypertensive patients, so there were no improvements in autonomic indices. There was a decrease in SBPV LF:HF indicating improved sympathovagal balance, but this was likely a result of lifestyle modification rather than IHG. Future studies are necessary to determine appropriate use of IHG as a treatment for hypertension and to verify the mechanisms responsible for BP attenuation with IHG.</p> / Thesis / Master of Science (MSc)

<p> Recent evidence suggests that isometric handgrip training improves resting arterial blood pressure (BP) in normotensive and hypertensive individuals, however the mechanisms remain elusive. The purposes of the current investigation were to replicate the finding that 8 weeks of isometric handgrip training (IHG) improve resting BP in persons medicated for hypertension, to determine if training could improve aortic stiffness and to examine the acute cardiovascular response to IHG. Seventeen participants were recruited and familiarized with the laboratory and techniques used. Training consisted of 8 weeks of thrice weekly IHG training sessions using a pre-programmed handgrip dynamometer (4, 2-minute contractions separated by 4 minutes rest). Measurements of resting ABP (assessed by automated oscillometry), aortic stiffness (assessed by simultaneous ultrasound and applanation tonometry), and the acute cardiovascular response (heart rate, blood pressure, rate-pressure product, and cardiac output) were made at baseline and following 8 weeks of IHG training.</p> <p> Following training, there were no differences observed in resting systolic or diastolic systolic blood pressure, resting heart rate or cardiac output. Furthermore, handgrip training did not improve aortic distensibility or reduce stiffness index. The acute responses of heart rate, blood pressure, rate pressure product and cardiac output were not altered with training. In response to an acute bout of IHG there were significant increases seen in heart rate (55±2 to 65±3 BPM, p<0.01), blood pressure (systolic: 137.2±3.7 to 157.1±7.3; diastolic: 77.8±3.4 to 92.2±4.8 mmHg, p<0.01) and rate-pressure product (7369.4±302.0 to 10159.0±666.6 beatsxmmHg/min). Thus isometric handgrip training is a safe modality which does not appear to alter the stiffness of the proximal aorta or generate a significant cardiovascular strain in the acute phase.</p> / Thesis / Master of Science (MSc)

<p> Hypertension and reduced arterial distensibility are independent risk factors for cardiovascular disease. Previous research has found that isometric training reduces resting blood pressure (RBP) (Wiley et al. 1992; Taylor et al. 2003) yet the mechanisms responsible remain elusive. Improved arterial distensibility may contribute to this reduction in RBP. The purpose of the present study was threefold: 1) to replicate the RBP lowering effect of isometric handgrip (IHG) exercise; 2) to compare IHG and isometric leg press (ILP) based in their RBP lowering effects; and 3) to determine if central or peripheral arterial distensibility improved with IHG or ILP. The population examined was people whom were medicated for hypertension.</p> <p> RBP, as assessed by brachial oscillometry, and arterial distensibility, as assessed by Doppler ultrasound and applanation tonometry in the carotid, brachial and femoral arteries, were measured pre training, after 4 weeks of training, and post training. Participants performed unilateral IHG exercise (n=10) or ILP exercise (n=9) 3 times/week for 8 weeks at 30% MVC or acted as a non-exercising control group (n=5).</p> <p> Results indicated that the present study was unable to reproduce the RBP reductions noted in previous studies using IHG exercise. Also, the ILP exercise group did not experience reductions in RBP. Finally, neither central nor peripheral arterial distensibility improved in the IHG or ILP group when compared to the control group.</p> <p> Although these findings are contrary to our hypotheses one must consider that the control group examined contained very few subjects. This may have limited our ability to detect statistically significant changes in RBP and arterial distensibility.</p> / Thesis / Master of Science (MSc)

This study examined the effects of isometric handgrip (IHG) training on resting blood pressure (RBP), heart rate variability (HRV) and blood pressure variability (BPV) in older adults with hypertension. Nine subjects performed four 2-minute IHG contractions at 30% maximal voluntary contraction (MVC) 3 days/week for 10 weeks and 8 subjects served as controls. Power spectral analysis (PSA) of HRV and BPV was used to assess changes in modulation of the autonomic nervous system. After training, there was a marked attenuation in arterial pressure and evidence for a shift in HR.V and BPV sympathovagal balance. There was a reduction in systolic blood pressure (156 ± 9.4 to 137 ± 7.8 mm Hg; p<0.05), diastolic blood pressure (82 ± 9.3 to 75 ± 10.9 mm Hg; N.S), mean arterial pressure (107 ± 8.53 to 96 ± 8.7 mm Hg; p<0.05) and resting heart rate (RHR) (70 ± 14.2 to 68 ± 12.1 beats/min). In addition, PSA of HRV showed a decrease in sympathetic modulation represented by low frequency (LF) area, an increase in parasympathetic modulation represented by high frequency (HF) area (p<0.05) and a decrease in LF:HF area ratio. After training, BPV PSA showed a decrease in systolic blood pressure LF area (p<0.05), an increase in HF area (p<0.05) and decrease in LF:HF area (p<0.05). Similar, but non-significant changes occurred in diastolic BPV. It is concluded that isometric training at a moderate intensity can elicit a hypotensive response and can potentially alter sympathovagal balance of HRV and BPV in older adults with hypertension. / Thesis / Master of Science (MS)

The rapid growth of an older demographic is an increasing concern around the world. Older people have been reported to suffer from physiological and neuromuscular declines in several systems including skeletal muscles, central nervous system, cardiovascular processes and respiratory function. These age-related changes are often reflected through impairments in functional performance of occupational tasks as well as activities of daily living. This may make an older population more prone to musculoskeletal disorders and injuries. In addition, health problems and injury risks are likely amplified by factors such as obesity. Obesity has emerged as a serious health concern in the United States in recent decades. However, obesity-related changes in performance and motor control as well as how they will be modified by gender, specifically among older adults, are still largely unexplored. As motor variability has recently been reported to be associated with fatigue development and may have the potential to reveal underlying mechanisms of neuromuscular control, the main goals of this study were to investigate the influence of gender and obesity on motor performance, neuromuscular control and endurance in the elderly, by examining differences in motor variability during intermittent submaximal isometric exertions of the knee and hand. Fifty-two older participants with age over 65 were recruited into four groups: obese male (9), obese female (13), non-obese male (15) and non-obese female (15). The obese groups consisted of those whose BMI was greater than 30 kg/m2. Participants were asked to perform intermittent (15s on and 15s off) isometric handgrip and knee extensions at 30% MVC until exhaustion. Force and muscle activations of the Vastus Lateralis, Rectus Femoris, Extensor Carpi Radialis and Flexor Carpi Radialis muscles were collected through the endurance task. Motor variability was quantified using the coefficient of variation (CV) and sample entropy (SaEn) of the surface electromyography (EMG) and force signals. Motor variability during exercise differed both between males and females, and between obese and non-obese people, reflecting different motor strategies employed in order to prolong endurance. Overall, across all individuals, we observed a significant positive correlation between cycle-to-cycle variability of knee extensor muscle activation during the baseline period of the task and endurance time. As for gender differences, males exhibited longer endurance times than females, and seemed to achieve that through utilizing a motor strategy involving a more variable (higher CV) and less complex (lower SaEn) agonistic muscle activity. Since this was accompanied by a lower fluctuation in the force signal (lower CV) and a higher complexity of force (SaEn), we interpreted this to be a motor strategy involving more variable recruitment of synergistic and antagonistic motor units during the knee extension task to prolong endurance time, among males compared to females. As for obesity differences, there were no obesity-related changes in endurance time. However, obese individuals exhibited a greater cycle-to-cycle variability that was positively correlated with endurance time during the knee extension task, indicating a larger alteration in the recruitment of motor units across successive contractions, which contributed to comparable endurance time and performance with their non-obese counterparts. During the hand-grip tasks, variabilities in force and muscle activity followed similar trends as the knee extension task. However, there were no significant gender or obesity differences in endurance time, and there also weren't any significant correlations between any of the dependent variables with endurance time. Thus, this study was a basic investigation into changes in motor variability and how it was associated with the development of fatigue among older adults; and the potential influences of gender and obesity on the relationships. Two tasks of high relevance to both occupational life and activities of daily living, i.e. knee extension and hand-grip were considered. Our findings enhance the theoretical understanding of the underlying neuromuscular control patterns and their relationship with fatigue for different individuals. Given that both aging and obesity rates are rising continuously and becoming a substantial health and safety problem especially in the occupational environment, the results from this study are both timely and critical for practical design applications, especially by recognizing the importance of having a variable motor pattern in task performance, even among older adults. / MS / Obesity rates in the geriatric population has emerged as serious health concern in recent decades. Yet, obesity-related differences in neuromuscular performance and neuromotor control during fatiguing tasks, as well as how they are modified by gender, specifically among older adults, are still largely unexplored. In recent decades, motor variability, referring to the natural variations in postures, movements and muscle activity, has been observed in all physical tasks and linked with fatigue development. It may have the potential to reveal underlying mechanisms of neuromuscular control. Thus, the main goals of this study were to investigate the influence of gender and obesity on motor variability and performance in the elderly, by studying intermittent isometric muscle contractions. Fifty-two older adults (Mean age: 73 (SD 6) years) were recruited into four groups: 9 obese males, 13 obese females, 15 non-obese males, and 15 non-obese females 15. Participants performed intermittent (15s contraction and 15s rest) isometric knee extensions and handgrips at 30% maximum voluntary contraction (MVC) until exhaustion. Force and muscle activations of the Vastus Lateralis (VL), Rectus Femoris (RF), Extensor Carpi Radialis (ECR) and Flexor Carpi Radialis (FCR) muscles were collected during knee extension and handgrip tasks. Performance was quantified using endurance time and force fluctuations. Motor variability was quantified using the coefficient of variation (CV) and sample entropy (SaEn) of the muscle activation signals (surface electromyography (EMG)). The CV is a linear estimator that quantified the size of motor variability. The SaEn is the non-linear estimator that can show the complexity of the signal. Across all individuals, larger cycle-to-cycle variability of baseline muscle activation was associated with longer endurance time during the knee extension task. Males exhibited longer endurance times than females, and probably achieved that by utilizing a motor strategy involving more variable recruitment of synergistic and antagonistic motor units during the knee extension task. No obesity-related changes in endurance time were found. However, obese individuals exhibited a greater cycle-to-cycle variability during the knee extension task, indicating a larger alteration in the recruitment of motor units across successive contractions, which contributed to comparable endurance time and performance with their non-obese counterparts. This study was a basic investigation into changes in motor variability and how it was associated with the development of fatigue among older adults; and the potential influences of gender and obesity on the relationships. Given that obesity rates in the older population is rising continuously and becoming a substantial health and safety problem especially in the occupational environment, the results from this study are both timely and critical for practical design applications, especially by recognizing the importance of having a variable motor pattern in task performance, particularly among older adults.

Water movement in the body is determined by the osmotic forces acting on the cell membrane. Ingestion of a highly-hypertonic glycerol solution resulting in high extracellular osmolality could drive water out of the intracellular space into the vascular space resulting in reduced muscle hydration and increased blood volume. The aim of this thesis was to study the effects of altered body water distribution during exercise. In chapter 3, ingestion of a 400 ml glycerol solution (1 g·kg-1 body mass) increased serum osmolality (309 mosmol·kg-1) which was associated with a 4.0% increase in blood volume due to a 7.2% increase in plasma volume, attributed to a shift of water from the intracellular space, resulting presumably in tissue dehydration. Glycerol ingestion was then used as a means of altering body water distribution in the other studies described in this thesis. Altered body water distribution had no acute effect on force production during quadriceps muscle isometric exercise (chapter 4), or handgrip strength (chapter 5). Regarding chronic effects (chapter 5), two groups of participants exercised handgrip and initiated recovery after ingestion of either a glycerol solution or placebo over a period of 8 weeks. Maximum handgrip strength increased in both groups and there was no statistically significant difference between the two groups. In chapters 6 and 7, the subjects performed a cycling exercise protocol to fatigue. In the glycerol trial, time to fatigue decreased compared with the iso-osmotic trial during an incremental VO2max test (chapter 6) and during cycling against a constant load at 100% VO2max intensity (chapter 7). In the glycerol trial, there was an accelerated increase in blood lactate and an accelerated increase in serum potassium (chapter 7), indicating altered muscle metabolism which may have contributed to the early development of fatigue.

Title: Excercise regimen in active seniors Aim: This thesis sets out to find out wheher the active elderly people follow guidance of general recommnedations for the excercise regimen designed for them. I'm trying to find out whether the frequency of excercise changes through positive biosocial variables. Secondary goals of the research are monitoring the activity preferences and the level of health condition of the elderly. The last secondary goal of the research is measuring the condition of their muscular apparatus with the help of a hand grip (hand squeezing test), that reflects to a great degree the physical ability of a person. Methods: In this thesis specialist publications were researched, content analysis of a survey was perfomed and a comparison of found results has been carried out. Results: The results for fulfilling the recommended excercise regimen by the active elderly population have been confirmed. The effect of some positive biosocial variables has been confirmed, albeit not all of them. We found out what excercise activities are preferred by our elderly and the test for their muscular strenght was performed to find that the elderly people, visiting fitness centers regularly are stronger than the rest of elderly population. Keywords: age, elderly, seniority, excercise activity,...

IMPORTÂNCIA: Mudanças significativas na composição corporal ocorrem com o envelhecimento, havendo aumento progressivo da massa gorda e redução da massa magra. Este quadro está associado à perda de força e mobilidade, ao aumento da morbidade e mortalidade. Nos indivíduos diabéticos tipo 2, esta condição é agravada pelas alterações metabólicas impostas pela doença. OBJETIVO: Comparar as medidas da composição corporal de idosas diabéticas tipo 2 pelo método antropométrico e raio-x de dupla varredura (DEXA), e correlacioná-las à força de preensão da mão. MÉTODOS: Cinqüenta e três voluntárias de 60 a 70 anos, com índice de massa corporal (IMC, kg/m2) de 19 a 44, do Ambulatório de Diabetes do Hospital das Clínicas da Faculdade de Medicina de Ribeirão Preto da Universidade de São Paulo, foram avaliadas por: medidas antropométricas, raio-x de dupla varredura e força de preensão da mão. RESULTADOS: a) composição corporal antropometria x DEXA: não houve diferença estatística entre os métodos para as médias do peso, massa corporal magra, massa corporal gorda, porcentagem de gordura total e porcentagem de gordura do braço (P > 0,05). O peso, a massa corporal magra, a massa corporal gorda e o percentual de gordura total foram significativamente correlacionados pelos dois métodos. b) índices corporais x DEXA: o IMC, a circunferência do abdômen, a circunferência muscular do braço, a porcentagem de gordura do braço, a área muscular do braço, a área de gordura do braço, foram significativamente correlacionados, com os respectivos componentes do DEXA (P < 0,05); o índice abdômen/quadril não foi correlacionado ao DEXA. c) comparação entre diversos índices antropométricos: foram significativamente correlacionados (P < 0,05), o IMC e a circunferência do abdômen com a porcentagem de gordura total da antropometria; a circunferência muscular do braço com a massa corporal magra da antropometria. Não foram correlacionados o IAQ com o IMC e com a porcentagem de gordura total da antropometria. d) coeficiente de variação para medidas corporais do DEXA: variou de 0,3% a 9,6% entre os diferentes componentes corporais. e) teste de preensão de mão x variáveis associadas à massa muscular: foi correlacionado a variáveis antropométricas (P < 0,05), e não ao DEXA. CONCLUSÃO: Os dois métodos foram equivalentes para avaliação da composição corporal, sugerindo que a antropometria pode produzir um bom resultado de avaliação nestas idosas diabéticas. A força de preensão da mão teve correlação com a antropometria, mas não com as variáveis do DEXA. Portanto, estas medidas podem contribuir na avaliação do estado nutricional e de saúde em idosas diabéticas tipo 2 e ainda, acompanhar de maneira fácil e barata, a evolução de um tratamento. / IMPORTANCE: A significant change in corporal composition occurs with aging, with increase of fat mass and reduction lean mass. This situation is associated with loss of strength and mobility, and increase of morbidity and mortality. In diabetic type 2 individuals, this condition is aggravated by the metabolic alterations due to the illness. OBJECTIVE: To compare the measures of body composition of elderly women with diabetes type 2 through anthropometry and dual-energy x-ray absorptiometry (DEXA), and correlate findings to handgrip strength. METHODS: Fifty-three volunteers with age ranging from 60 to 70 years old, body mass index (BMI, kg/m2) 19 to 44 selected from the Diabetes Ambulatory of the Clinical Hospital of the School of Medicine of Ribeirão Preto, University of São paulo, were evaluated by: anthropometry, DEXA and handgrip strength. RESULTS: a) anthropometry x DEXA in body composition analyses: there were no statistical differences between the average of the weight, lean body mass, fat body mass, percentage of body fatness and percentage of fatness of the arm (P > 0,05). The weight, lean body mass, body fat mass and percentage of body fatness were significantly correlated. b) body indices x DEXA: BMI, abdomen circumference, muscle arm circumference, percentage of fatness of the arm, muscular area of the arm and area of fatness of the arm were significantly correlated with the respective components of the DEXA (P < 0,05); the waist/hip ratio (WHR) was not correlated with DEXA (P < 0,05): c) comparison between athropometric indices: the following variables were significantly correlated (P < 0,05): BMI and circumference of the abdomen with the percentage of body fatness of the anthropometry; muscular circumference of the arm with the lean body mass of the anthropometry. The WHR was not correlated with the IMC and with the percentage of body fatness of the anthropometry. d) coefficient of variation for corporal measures of the DEXA: varied from 0,3% to 9,6%. Handgrip strength was correlated to anthropometrics variables (P <0,05), but not with DEXA. CONCLUSIONS: The two approaches were equivalent for the assessment of body composition, suggesting that anthropometry can produce a good result in the evaluation of this population. The handgrip strength was correlated with anthropometry, but not with the variables of DEXA. Therefore, these measures can contribute to the assessment of the nutritional status in elderly diabetic type 2.