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Isometric Exercise (isometric + exercise)
Selected AbstractsResponse of retinal arteriole diameter to increased blood pressure during acute hyperglycaemiaACTA OPHTHALMOLOGICA, Issue 3 2007Peter Jeppesen Abstract. Purpose:, To study retinal response in terms of arteriole diameter and retinal thickness secondary to an increase in arterial blood pressure during acute hyperglycaemia. Methods:, In a randomized, double-blinded, cross-over study, nine healthy persons were subjected to clamping of blood glucose to either 5 mmol/l or 15 mmol/l using somatostatin to control endogenous insulin secretion. The response of retinal arterioles in terms of diameter as determined with the retinal vessel analyser (RVA) and retinal thickness as assessed by optical coherence tomography (OCT) were measured after an increase in arterial blood pressure induced by isometric exercise. Arterial feeding pressure in the eye was assessed from the ophthalmic artery pressure and pulse amplitude measured by ophthalmodynamometry. Results:, Isometric exercise induced a significant increase in mean arterial blood pressure and a significant contraction of the retinal arterioles. An acute increase in blood glucose from 5 mmol/l to 15 mmol/l did not affect either the diameter of retinal vessels or retinal thickness. Conclusions:, Acute hyperglycaemia per se does not change isometric exercise-induced retinal arteriolar contraction. Metabolic factors other than blood glucose are suspected to be involved in the impairment of retinal autoregulation as seen in hyperglycaemia induced by oral glucose intake. [source] Effect of isometric exercise and body scanning on cigarette cravings and withdrawal symptomsADDICTION, Issue 7 2009Michael Ussher ABSTRACT Aims To examine the acute effects of a guided relaxation routine (body scan) and isometric exercise on desire to smoke and tobacco withdrawal symptoms. Design Experimental comparison of three conditions. Participants Forty-eight individuals reporting smoking ,10 cigarettes daily. Intervention Random assignment to one of three interventions delivered via a 10-minute audio: isometric exercise (IE, n = 14), body scanning (BS, n = 18) or a reading about natural history (control group, n = 16). Interventions were delivered twice on the same day: in the laboratory, then in their ,normal' environment. Measurements Desire to smoke (primary outcome) and withdrawal symptoms were rated at pre-intervention and up to 30 minutes post-intervention. Findings Controlling for baseline scores, post-intervention desire to smoke and withdrawal symptoms were significantly lower for IE and BS groups, compared with the controls, in both environments. There were no significant differences for IE versus BS. For desire to smoke, controlling for baseline values, ratings in the laboratory were significantly lower for IE and BS versus the control up to 30 minutes post-intervention. In the normal environment, these ratings were significantly lower only up to 5 minutes post-intervention. Conclusions Brief IE and BS interventions are effective for reducing desire to smoke and withdrawal symptoms in temporarily abstaining smokers. These interventions were found to be more effective in the laboratory than in the smoker's normal environment, but this may be an artefact of there not being a sufficient ,wash-out' period between interventions. These techniques may be beneficial for managing desire to smoke and tobacco withdrawal. [source] Myocardial perfusion defects in Bartter and Gitelman syndromesEUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 12 2008R. Scognamiglio ABSTRACT Background, Normotensive hypokalaemic tubulopathies (Bartter and Gitelman syndromes (BS/GS)) are genetic diseases that are considered benign. However, QT prolongation, left ventricular dysfunction and reduction of cardiac index upon exercise leading to arrhythmias and sudden cardiac death have been reported in these patients. Hence, we aimed to verifying whether an isometric exercise could represent a useful tool for the identification of patients at risk for future cardiac events. Patients and methods, Myocardial function (MF) and perfusion, evaluated as myocardial blood flow (MBF) of 10 BS/GS patients and 10 healthy controls, were investigated at rest and during isometric exercise. MF and MBF were evaluated using quantitative two-dimensional and myocardial contrast echocardiography. Results, BS/GS patients had normal baseline MF and MBF. During exercise in BS/GS patients, corrected QT (QTc) was prolonged to peak value of 494 ± 9·1 ms (P < 0·001). In controls, MF increased from resting to peak exercise (left ventricular ejection fraction: 65 ± 4% to 78 ± 5%, P < 0·003) while in seven BS/GS patients (Group 1) it declined (64 ± 5% to 43 ± 9%, P < 0·001). Myocardial perfusion increased upon exercise in controls as shown by changes of its markers: , (a measure of myocardial flow velocity; 0·89 ± 0·12 vs. 0·99 ± 0·12, P < 0·001) and myocardial blood volume (14·4 ± 2 vs. 20·2 ± 0·25, P < 0·001), while in Group 1 BS/GS it decreased (0·87 ± 0·15 vs. 0·67 ± 0·15, P < 0·001; and 14·5 ± 1·9 vs. 8·3 ± 0·22, P < 0·001, respectively). Conclusions, Our results document for the first time that exercise induce coronary microvascular and myocardial defects in BS/GS patients. Therefore, this may challenge the idea that BS/GS are benign diseases. In addition, the diagnostic approach to these syndromes should include an in-depth cardiac assessment in order to identify patients at higher risk. [source] Muscle afferent contributions to the cardiovascular response to isometric exerciseEXPERIMENTAL PHYSIOLOGY, Issue 6 2004James P. Fisher The cardiovascular response to isometric exercise is governed by both central and peripheral mechanisms. Both metabolic and mechanical stresses on the exercising skeletal muscle produce cardiovascular change, yet it is often overlooked that the afferent signal arising from the muscle can be modified by factors other than exercise intensity. This review discusses research revealing that muscle fibre type, muscle mass and training status are important factors in modifying this peripheral feedback from the active muscles. Studies in both animals and humans have shown that the pressor response resulting from exercise of muscle with a faster contractile character and isomyosin content is greater than that from a muscle of slower contractile character. Athletic groups participating in training programmes that place a high anaerobic load on skeletal muscle groups show attenuated muscle afferent feedback. Similarly, longitudinal studies have shown that specific local muscle training also blunts the pressor response to isometric exercise. Thus it appears that training may decrease the metabolic stimulation of muscle afferents and in some instances chronic exposure to the products of anaerobic metabolism may blunt the sensitivity of the muscle metaboreflex. There may be surprising parallels between the local muscle conditions induced in athletes training for longer sprint events (e.g. 400 m) and by the low-flow conditions in, for example, the muscles of chronic heart failure patients. Whether their similar attenuations in muscle afferent feedback during exercise are due to decreased metabolite accumulation or to a desensitization of the muscle afferents is not yet known. [source] The effects of isometric exercise on maximum voluntary bite forces and jaw muscle strength and enduranceJOURNAL OF ORAL REHABILITATION, Issue 10 2001D. J. Thompson The effects of training and exercise on the strength and endurance of limb muscles has been investigated extensively, but the response of the jaw muscles to exercise remains poorly known. The purpose of this study was to determine whether short-term isometric training increases strength and endurance of the superficial masseter and anterior temporalis muscles. Maximum and submaximum voluntary bite forces and corresponding electromyographic (EMG) activity were measured in 28 young adults, randomly divided into exercise and non-exercise (control) groups. Subjects in the exercise group performed isometric clenches against a soft maxillary splint for five 1-min sessions per day over a 6-week period. After exercise, subjects increased their maximum bite forces by 37%, but control subjects' bite forces also increased by 25%. After exercise, EMG levels per unit of bite force generally decreased, but similar decreases were also seen in the non-exercised controls. Masseter muscle activity levels during standardized 10-kg bites decreased after 6 weeks of exercise. Fatigue resistance increased significantly with exercise but did not differ significantly from control values after 6 weeks of exercise. The results of this study indicate that increases in maximum bite force can be easily produced with training, but that actual strengthening of the jaw muscles is more difficult to achieve. [source] An additional phase in PCr use during sustained isometric exercise at 30% MVC in the tibialis anterior muscleNMR IN BIOMEDICINE, Issue 4 2002C. J. Houtman Abstract The occurrence of an abrupt acceleration in phosphocreatine hydrolysis in the tibial anterior muscle during the last part of a sustained isometric exercise at 30% maximal voluntary contraction until fatigue is demonstrated in seven out of eight healthy subjects by applying in vivo31P NMR spectroscopy at 1.5,T field strength. This additional third phase in PCr hydrolysis, is preceded by a common biphasic pattern (first fast then slow) in PCr use. The NMR spectra, as localized by a surface coil and improved by proton irradiation, were collected at a time resolution of 16 s. Mean rates of PCr hydrolysis during exercise were ,0.44,±,0.19% s,1, ,0.07,±,0.04% s,1, and ,0.29,±,0.10% s,1 for the three successive phases. The increased rate of PCr hydrolysis, and also the loss of fine force control evident in the force records are consistent with increased involvement of large, fast-fatiguable units later in the contraction. Copyright © 2002 John Wiley & Sons, Ltd. [source] Central command and the cutaneous vascular response to isometric exercise in heated humansTHE JOURNAL OF PHYSIOLOGY, Issue 2 2005Manabu Shibasaki Cutaneous vascular conductance (CVC) decreases during isometric handgrip exercise in heat stressed individuals, and we hypothesized that central command is involved in this response. Seven subjects performed 2 min of isometric handgrip exercise (35% of maximal voluntary contraction) followed by postexercise ischaemia in normothermia and during heat stress (increase in internal temperature ,1°C). To augment the contribution of central command independent of force generation, on a separate day the protocol was repeated following partial neuromuscular blockade (PNB; i.v. cisatracurium). Forearm skin blood flow was measured by laser-Doppler flowmetry, and CVC was the ratio of skin blood flow to mean arterial pressure. The PNB attenuated force production despite encouragement to attain the same workload. During the heat stress trials, isometric exercise decreased CVC by ,12% for both conditions, but did not change CVC in either of the normothermic trials. During isometric exercise in the heat, the increase in mean arterial pressure (MAP) was greater during the control trial relative to the PNB trial (31.0 ± 9.8 versus 18.6 ± 6.4 mmHg, P < 0.01), while the elevation of heart rate tended to be lower (19.4 ± 10.4 versus 27.4 ± 8.1 b.p.m., P= 0.15). During postexercise ischaemia, CVC and MAP returned to pre-exercise levels in the PNB trial but remained reduced in the control trial. These findings suggest that central command, as well as muscle metabo-sensitive afferent stimulation, contributes to forearm cutaneous vascular responses in heat stressed humans. [source] 2323: Role of nitric oxide in optic nerve head blood flow regulation during isometric exercise in healthy humansACTA OPHTHALMOLOGICA, Issue 2010D SCHMIDL Purpose Nitric oxide (NO) is an important regulator of optic nerve head (ONH) blood flow in humans. We have previously shown that NO is also involved in choroidal blood flow regulation during isometric exercise. Inhibition of NO synthase (NOS) has been reported to shift choroidal pressure,flow curves during squatting to the right. The hypothesis for the present study was that inhibition of NOS may also influence ONH blood flow during isometric exercise. Methods To test this hypothesis, a randomized, double-masked, placebo-controlled, three-way crossover study was performed in 18 healthy volunteers. Subjects received on different study days intravenous infusions of NG-monomethyl- L-arginine (L-NMMA), phenylephrine, or placebo. During these infusion periods, subjects were asked to squat for 6 minutes. ONH blood flow was assessed with laser Doppler flowmetry, and ocular perfusion pressure (OPP) was calculated from mean arterial pressure and intraocular pressure. Results L-NMMA and phenylephrine increased resting OPP (p < 0.001 versus baseline), but only L-NMMA reduced resting ONH blood flow (p = 0.02 versus baseline). The relative increase in OPP during isometric exercise was comparable with all drugs administered (p = 0.69). In addition, the change of ONH blood flow was comparable with all administered drugs (p = 0.43). Conclusion These data indicate that NO plays an important role in the regulation of ONH blood flow at baseline, but does not change the response of ONH blood flow during isometric exercise. [source] Response of retinal arteriole diameter to increased blood pressure during acute hyperglycaemiaACTA OPHTHALMOLOGICA, Issue 3 2007Peter Jeppesen Abstract. Purpose:, To study retinal response in terms of arteriole diameter and retinal thickness secondary to an increase in arterial blood pressure during acute hyperglycaemia. Methods:, In a randomized, double-blinded, cross-over study, nine healthy persons were subjected to clamping of blood glucose to either 5 mmol/l or 15 mmol/l using somatostatin to control endogenous insulin secretion. The response of retinal arterioles in terms of diameter as determined with the retinal vessel analyser (RVA) and retinal thickness as assessed by optical coherence tomography (OCT) were measured after an increase in arterial blood pressure induced by isometric exercise. Arterial feeding pressure in the eye was assessed from the ophthalmic artery pressure and pulse amplitude measured by ophthalmodynamometry. Results:, Isometric exercise induced a significant increase in mean arterial blood pressure and a significant contraction of the retinal arterioles. An acute increase in blood glucose from 5 mmol/l to 15 mmol/l did not affect either the diameter of retinal vessels or retinal thickness. Conclusions:, Acute hyperglycaemia per se does not change isometric exercise-induced retinal arteriolar contraction. Metabolic factors other than blood glucose are suspected to be involved in the impairment of retinal autoregulation as seen in hyperglycaemia induced by oral glucose intake. [source] The effect of inferior turbinate hypertrophy on nasal spray distribution to the middle meatus,CLINICAL OTOLARYNGOLOGY, Issue 6 2001A.C. Dowley The effect of inferior turbinate hypertrophy on nasal spray distribution to the middle meatus The distribution of topical nasal sprays is suboptimal, the main obstruction to adequate delivery in normal volunteers being the nasal valve. We aimed to test the hypothesis that, in patients with rhino-sinusitis, hypertrophy of the inferior turbinate also limits the distribution of administered drug to the middle meatus. We modelled the effect of inferior turbinate hypertrophy and reduction by effecting congestion (by ipsilateral isometric exercise) and decongestion (topical oxymetazoline) in normal volunteers. The method chosen to estimate drug delivery to the middle meatus used endoscopic photography after the administration of dyed aqueous spray. A randomized cross-over study design was used and 20 nasal cavities were studied. The congestion/decongestion manoeuvres significantly altered nasal airflow, as measured by peak inspiratory nasal flow (P < 0.001). Congestion diminished significantly drug delivery to the middle meatus, as compared with decongestion (P = 0.026). This may support a clinical role for inferior turbinate reduction to improve the efficacy of topical nasal therapy, as well as improving nasal airflow. [source] | |||||||||||||