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Sallam NA, Wang B, Laher I. Exercise training and vascular heterogeneity in db/db mice: evidence for regional- and duration-dependent effects. NAUNYN-SCHMIEDEBERG'S ARCHIVES OF PHARMACOLOGY 2024; 397:2421-2436. [PMID: 37843589 DOI: 10.1007/s00210-023-02775-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2023] [Accepted: 10/04/2023] [Indexed: 10/17/2023]
Abstract
Exercise training (ET) has several health benefits; however, our understanding of regional adaptations to ET is limited. We examined the functional and molecular adaptations to short- and long-term ET in elastic and muscular conduit arteries of db/db mice in relation to changes in cardiovascular risk factors. Diabetic mice and their controls were exercised at moderate intensity for 4 or 8 weeks. The vasodilatory and contractile responses of thoracic aortae and femoral arteries isolated from the same animals were examined. Blood and aortic samples were used to measure hyperglycemia, oxidative stress, inflammation, dyslipidemia, protein expression of SOD isoforms, COX, eNOS, and Akt. Short-term ET improved nitric oxide (NO) mediated vasorelaxation in the aortae and femoral arteries of db/db mice in parallel with increased SOD2 and SOD3 expression, reduced oxidative stress and triglycerides, and independent of weight loss, glycemia, or inflammation. Long-term ET reduced body weight in parallel with reduced systemic inflammation and improved insulin sensitivity along with increased SOD1, Akt, and eNOS expression and improved NO vasorelaxation. Exercise did not restore NOS- and COX-independent vasodilatation in femoral arteries, nor did it mitigate the hypercontractility in the aortae of db/db mice; rather ET transiently increased contractility in association with upregulated COX-2. Long-term ET differentially affected the aortae and femoral arteries contractile responses. ET improved NO-mediated vasodilation in both arteries likely due to collective systemic effects. ET did not mitigate all diabetes-induced vasculopathies. Optimization of the ET regimen can help develop comprehensive management of type 2 diabetes.
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Affiliation(s)
- Nada A Sallam
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Cairo University, Cairo, 11562, Egypt
| | - Baohua Wang
- Department of Anesthesiology, Pharmacology and Therapeutics, University of British Columbia, Vancouver, BC, V6T1Z4, Canada
| | - Ismail Laher
- Department of Anesthesiology, Pharmacology and Therapeutics, University of British Columbia, Vancouver, BC, V6T1Z4, Canada.
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Dech S, Bittmann FN, Schaefer LV. Muscle oxygenation and time to task failure of submaximal holding and pulling isometric muscle actions and influence of intermittent voluntary muscle twitches. BMC Sports Sci Med Rehabil 2022; 14:55. [PMID: 35354469 PMCID: PMC8966203 DOI: 10.1186/s13102-022-00447-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Accepted: 03/23/2022] [Indexed: 08/30/2023]
Abstract
Background Isometric muscle actions can be performed either by initiating the action, e.g., pulling on an immovable resistance (PIMA), or by reacting to an external load, e.g., holding a weight (HIMA). In the present study, it was mainly examined if these modalities could be differentiated by oxygenation variables as well as by time to task failure (TTF). Furthermore, it was analyzed if variables are changed by intermittent voluntary muscle twitches during weight holding (Twitch). It was assumed that twitches during a weight holding task change the character of the isometric muscle action from reacting (≙ HIMA) to acting (≙ PIMA). Methods Twelve subjects (two drop outs) randomly performed two tasks (HIMA vs. PIMA or HIMA vs. Twitch, n = 5 each) with the elbow flexors at 60% of maximal torque maintained until muscle failure with each arm. Local capillary venous oxygen saturation (SvO2) and relative hemoglobin amount (rHb) were measured by light spectrometry. Results Within subjects, no significant differences were found between tasks regarding the behavior of SvO2 and rHb, the slope and extent of deoxygenation (max. SvO2 decrease), SvO2 level at global rHb minimum, and time to SvO2 steady states. The TTF was significantly longer during Twitch and PIMA (incl. Twitch) compared to HIMA (p = 0.043 and 0.047, respectively). There was no substantial correlation between TTF and maximal deoxygenation independently of the task (r = − 0.13). Conclusions HIMA and PIMA seem to have a similar microvascular oxygen and blood supply. The supply might be sufficient, which is expressed by homeostatic steady states of SvO2 in all trials and increases in rHb in most of the trials. Intermittent voluntary muscle twitches might not serve as a further support but extend the TTF. A changed neuromuscular control is discussed as possible explanation. Supplementary Information The online version contains supplementary material available at 10.1186/s13102-022-00447-9.
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Affiliation(s)
- Silas Dech
- Department of Sport and Health Sciences, Regulative Physiology and Prevention, Human Science Faculty, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14479, Potsdam, Germany.
| | - Frank N Bittmann
- Department of Sport and Health Sciences, Regulative Physiology and Prevention, Human Science Faculty, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14479, Potsdam, Germany
| | - Laura V Schaefer
- Department of Sport and Health Sciences, Regulative Physiology and Prevention, Human Science Faculty, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14479, Potsdam, Germany
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Dech S, Bittmann FN, Schaefer LV. Muscle Oxygenation Level Might Trigger the Regulation of Capillary Venous Blood Filling during Fatiguing Isometric Muscle Actions. Diagnostics (Basel) 2021; 11:1973. [PMID: 34829320 PMCID: PMC8621102 DOI: 10.3390/diagnostics11111973] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Revised: 10/19/2021] [Accepted: 10/19/2021] [Indexed: 01/14/2023] Open
Abstract
The regulation of oxygen and blood supply during isometric muscle actions is still unclear. Recently, two behavioral types of oxygen saturation (SvO2) and relative hemoglobin amount (rHb) in venous microvessels were described during a fatiguing holding isometric muscle action (HIMA) (type I: nearly parallel behavior of SvO2 and rHb; type II: partly inverse behavior). The study aimed to ascertain an explanation of these two regulative behaviors. Twelve subjects performed one fatiguing HIMA trial with each arm by weight holding at 60% of the maximal voluntary isometric contraction (MVIC) in a 90° elbow flexion. Six subjects additionally executed one fatiguing PIMA trial by pulling on an immovable resistance with 60% of the MVIC with each side and same position. Both regulative types mentioned were found during HIMA (I: n = 7, II: n = 17) and PIMA (I: n = 3, II: n = 9). During the fatiguing measurements, rHb decreased initially and started to increase in type II at an average SvO2-level of 58.75 ± 2.14%. In type I, SvO2 never reached that specific value during loading. This might indicate the existence of a threshold around 59% which seems to trigger the increase in rHb and could explain the two behavioral types. An approach is discussed to meet the apparent incompatibility of an increased capillary blood filling (rHb) despite high intramuscular pressures which were found by other research groups during isometric muscle actions.
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Affiliation(s)
- Silas Dech
- Devision of Regulative Physiology and Prevention, Department of Sports and Health Sciences, University of Potsdam, 14476 Potsdam, Germany; (F.N.B.); (L.V.S.)
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Dech S, Bittmann F, Schaefer L. Behavior of oxygen saturation and blood filling in the venous capillary system of the biceps brachii muscle during a fatiguing isometric action. Eur J Transl Myol 2020; 30:8800. [PMID: 32499884 PMCID: PMC7254419 DOI: 10.4081/ejtm.2019.8800] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Accepted: 02/08/2020] [Indexed: 11/23/2022] Open
Abstract
The objective of the study was to develop a better understanding of the capillary circulation in contracting muscles. Ten subjects were measured during a submaximal fatiguing isometric muscle action by use of the O2C spectrophotometer. In all measurements the capillary-venous oxygen saturation of hemoglobin (SvO2) decreased immediately after the start of loading and leveled off into a steady state. However, two different patterns (type I and type II) emerged. They differed in the extent of deoxygenation (-10.37 ±2.59 percent points (pp) vs. -33.86 ±17.35 pp, p = .008) and the behavior of the relative hemoglobin amount (rHb). Type I revealed a positive rank correlation of SvO2 and rHb (ρ = 0.735, p <.001), whereas a negative rank correlation (ρ = -0.522, p <.001) occurred in type II, since rHb decreased until a reversal point, then increased averagely 13% above the baseline value and leveled off into a steady state. The results reveal that a homeostasis of oxygen delivery and consumption during isometric muscle actions is possible. A rough distinction in two types of regulation is suggested.
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Affiliation(s)
- Silas Dech
- Regulative Physiology and Prevention, Department of Sport and Health Sciences, University of Potsdam, Germany
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Gildea N, Rocha J, McDermott A, O'Shea D, Green S, Egaña M. Influence of type 2 diabetes on muscle deoxygenation during ramp incremental cycle exercise. Respir Physiol Neurobiol 2019; 269:103258. [PMID: 31349019 DOI: 10.1016/j.resp.2019.103258] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Revised: 07/04/2019] [Accepted: 07/23/2019] [Indexed: 11/18/2022]
Abstract
We tested the hypothesis that type 2 diabetes (T2D) alters the profile of muscle fractional oxygen (O2) extraction (near-infrared spectroscopy) during incremental cycle exercise. Seventeen middle-aged individuals with uncomplicated T2D and 17 controls performed an upright ramp test to exhaustion. The rate of muscle deoxygenation (i.e. deoxygenated haemoglobin and myoglobin concentration, Δ[HHb+Mb]) profiles of the vastus lateralis muscle were normalised to 100% of the response, plotted against % power output (PO) and fitted with a double linear regression model. Peak oxygen uptake was significantly (P < 0.05) reduced in individuals with T2D. The %Δ[HHb+Mb]/%PO slope of the first linear segment of the double linear regression function was significantly (P < 0.05) steeper in T2D than controls (1.59 (1.14) vs 1.23 (0.51)). Both groups displayed a near-plateau in Δ[HHb+Mb] at an exercise intensity (%PO) not different amongst them. Such findings suggest that a reduced O2 delivery to active muscles is an important underlying cause of exercise intolerance during a maximum graded test in middle-aged individuals with T2D.
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Affiliation(s)
- Norita Gildea
- Department of Physiology, School of Medicine, Trinity College Dublin, Dublin, Ireland
| | - Joel Rocha
- Division of Sport and Exercise Sciences, Abertay University, Dundee, UK
| | - Adam McDermott
- Department of Physiology, School of Medicine, Trinity College Dublin, Dublin, Ireland
| | - Donal O'Shea
- Endocrinology, St Columcille's and St Vincent's Hospitals, Dublin, Ireland
| | - Simon Green
- School of Science and Health, Western Sydney University, Sydney, Australia
| | - Mikel Egaña
- Department of Physiology, School of Medicine, Trinity College Dublin, Dublin, Ireland.
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Hsieh PL, Tseng CH, Tseng YJ, Yang WS. Resistance Training Improves Muscle Function and Cardiometabolic Risks But Not Quality of Life in Older People With Type 2 Diabetes Mellitus: A Randomized Controlled Trial. J Geriatr Phys Ther 2018; 41:65-76. [DOI: 10.1519/jpt.0000000000000107] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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Poitras VJ, Hudson RW, Tschakovsky ME. Exercise intolerance in Type 2 diabetes: is there a cardiovascular contribution? J Appl Physiol (1985) 2018; 124:1117-1139. [PMID: 29420147 DOI: 10.1152/japplphysiol.00070.2017] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Physical activity is critically important for Type 2 diabetes management, yet adherence levels are poor. This might be partly due to disproportionate exercise intolerance. Submaximal exercise tolerance is highly sensitive to muscle oxygenation; impairments in exercising muscle oxygen delivery may contribute to exercise intolerance in Type 2 diabetes since there is considerable evidence for the existence of both cardiac and peripheral vascular dysfunction. While uncompromised cardiac output during submaximal exercise is consistently observed in Type 2 diabetes, it remains to be determined whether an elevated cardiac sympathetic afferent reflex could sympathetically restrain exercising muscle blood flow. Furthermore, while deficits in endothelial function are common in Type 2 diabetes and are often cited as impairing exercising muscle oxygen delivery, no direct evidence in exercise exists, and there are several other vasoregulatory mechanisms whose dysfunction could contribute. Finally, while there are findings of impaired oxygen delivery, conflicting evidence also exists. A definitive conclusion that Type 2 diabetes compromises exercising muscle oxygen delivery remains premature. We review these potentially dysfunctional mechanisms in terms of how they could impair oxygen delivery in exercise, evaluate the current literature on whether an oxygen delivery deficit is actually manifest, and correspondingly identify key directions for future research.
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Affiliation(s)
- Veronica J Poitras
- School of Kinesiology and Health Studies, Queen's University , Kingston, Ontario , Canada.,Department of Physiology, Queen's University , Kingston, Ontario , Canada.,Children's Hospital of Eastern Ontario, Research Institute , Ottawa, Ontario , Canada
| | - Robert W Hudson
- Department of Medicine, Division of Endocrinology, Queen's University , Kingston, Ontario , Canada
| | - Michael E Tschakovsky
- School of Kinesiology and Health Studies, Queen's University , Kingston, Ontario , Canada
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Increased left ventricular mass index is present in patients with type 2 diabetes without ischemic heart disease. Sci Rep 2018; 8:926. [PMID: 29343820 PMCID: PMC5772487 DOI: 10.1038/s41598-018-19229-w] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2017] [Accepted: 11/22/2017] [Indexed: 01/13/2023] Open
Abstract
Left ventricular mass index (LVMI) increase has been described in hypertension (HTN), but less is known about its association with type 2 diabetes (T2DM). As these conditions frequently co-exist, we investigated the association of T2DM, HTN and both with echocardiographic parameters, and hypothesized that patients with both had highest LVMI, followed by patients with only T2DM or HTN. Study population included 101 T2DM patients, 62 patients with HTN and no T2DM, and 76 patients with T2DM and HTN, excluded for ischemic heart disease. Demographic and clinical data, biochemical measurements, stress echocardiography, transthoracic 2D Doppler and tissue Doppler echocardiography were performed. Multivariable logistic regression was used to determine the independent association with T2DM. Linear regression models and Pearson's correlation were used to assess the correlations between LVMI and other parameters. Patients with only T2DM had significantly greater LVMI (84.9 ± 20.3 g/m2) compared to patients with T2DM and HTN (77.9 ± 16 g/m2) and only HTN (69.8 ± 12.4 g/m2). In multivariate logistic regression analysis, T2DM was associated with LVMI (OR 1.033, 95%CI 1.003-1.065, p = 0.029). A positive correlation of LVMI was found with fasting glucose (p < 0.001) and HbA1c (p = 0.0003). Increased LVMI could be a potential, pre-symptomatic marker of myocardial structural change in T2DM.
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Niedzwiecki P, Naskret D, Pilacinski S, Pempera M, Uruska A, Adamska A, Zozulinska-Ziolkiewicz D. The Higher the Insulin Resistance the Lower the Cardiac Output in Men with Type 1 Diabetes During the Maximal Exercise Test. Metab Syndr Relat Disord 2017; 15:252-257. [PMID: 28394194 DOI: 10.1089/met.2017.0007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
BACKGROUND The aim of this study was to assess the hemodynamic parameters analyzed in bioimpedance cardiography during maximal exercise in patients with type 1 diabetes differing in insulin resistance. METHODS The study group consisted of 40 men with type 1 diabetes. Tissue sensitivity to insulin was assessed on the basis of the glucose disposal rate (GDR) analyzed during hyperinsulinemic-euglycemic clamp. Patients were divided into groups with GDR <4.5 mg/kg/min (G1 group-lower insulin sensitivity) and GDR ≥4.5 mg/kg/min (G2 group-higher insulin sensitivity). During the exercise test, the heart rate, systolic volume, cardiac output, cardiac index were measured by the impedance meter (PhysioFlow). RESULTS Compared with the G2 group, the G1 group had a lower cardiac output (CO): during exercise 8.6 (IQR 7.7-10.0) versus 12.8 (IQR 10.8-13.7) L/min; P < 0.0001, at the maximal effort 13.1 (IQR 12.2-16.7) versus 18.6 (IQR 16.9-20.2) L/min; P = 0.001, and during observation after exercise 8.4 (IQR 6.3-9.6) versus 11.9 (IQR 10.1-13.1) L/min; P < 0.0001. We noticed a positive correlation of GDR and cardiac output: during the exercise test (r = 0.63, P = 0.0002), at the maximal effort (Rs 0.56, P = 0.001), and during observation after the exercise test (r = 0.72, P < 0.0001). In multivariate logistic regression, cardiac output during exercise and during observation was associated with high GDR, regardless of the age and duration of diabetes [OR: 1.98 (95% CI 1.10-3.56), P = 0.02 and OR: 1.91 (95% CI 1.05-3.48), P = 0.03; respectively]. CONCLUSION In nonobese subjects with type 1 diabetes, with good metabolic control, insulin resistance is associated with cardiac hemodynamic parameters assessed during and after exercise. The higher the insulin resistance the lower the cardiac output during maximal exercise in men with type 1 diabetes.
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Affiliation(s)
- Pawel Niedzwiecki
- Department of Internal Medicine and Diabetology, Poznan University of Medical Sciences , Poznan, Poland
| | - Dariusz Naskret
- Department of Internal Medicine and Diabetology, Poznan University of Medical Sciences , Poznan, Poland
| | - Stanislaw Pilacinski
- Department of Internal Medicine and Diabetology, Poznan University of Medical Sciences , Poznan, Poland
| | - Maciej Pempera
- Department of Internal Medicine and Diabetology, Poznan University of Medical Sciences , Poznan, Poland
| | - Aleksandra Uruska
- Department of Internal Medicine and Diabetology, Poznan University of Medical Sciences , Poznan, Poland
| | - Anna Adamska
- Department of Internal Medicine and Diabetology, Poznan University of Medical Sciences , Poznan, Poland
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Regensteiner JG, Bauer TA, Huebschmann AG, Herlache L, Weinberger HD, Wolfel EE, Reusch JEB. Sex differences in the effects of type 2 diabetes on exercise performance. Med Sci Sports Exerc 2016; 47:58-65. [PMID: 24811327 DOI: 10.1249/mss.0000000000000371] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
PURPOSE People with uncomplicated type 2 diabetes (T2D) have impaired peak exercise performance compared with that of their nondiabetic counterparts. This impairment may represent the earliest indication of cardiovascular (CV) abnormalities in T2D. Women with T2D are known to have worse CV outcomes than those in men with T2D. We hypothesized that women with diabetes have a greater exercise impairment than that in men with diabetes compared with that in their nondiabetic counterparts. METHODS We studied 15 women (premenopausal) and 14 men with T2D as well as their nondiabetic counterparts (22 women and 13 men). Exercise testing was performed. Additional outcomes included measurements of insulin sensitivity, endothelial function, blood flow, and resting cardiac function. RESULTS Men and women with T2D but not controls had impaired insulin sensitivity. Women with T2D had a lower peak oxygen consumption (V˙O2peak) compared with that of nondiabetic women (24%, P < 0.05) than men with diabetes compared with that in nondiabetic men (16%, P < 0.05) (P value between groups < 0.05). The time constants (phase 2) of the V˙O2 kinetic response tended to be slower in men and women with T2D than those in nondiabetic controls (P = 0.08). There were no differences in resting ventricular function by Doppler echocardiography techniques between groups. Women with T2D had significantly lower flow-mediated dilation and blood flow responses to hyperemia than those in nondiabetic women (both P < 0.05), whereas men with T2D had lower flow-mediated dilation but not lower blood flow than those in nondiabetic men. CONCLUSIONS Although both men and women with uncomplicated T2D had a lower V˙O2peak, the abnormality in women with T2D compared with that in nondiabetic women was greater than that seen in men. Because V˙O2peak has a strong inverse correlation with mortality, sex disparities observed in exercise capacity among people with T2D suggest a possible rationale for the increased CV morbidity and mortality observed in women compared with those observed in men with uncomplicated T2D.
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Affiliation(s)
- Judith G Regensteiner
- 1Department of Medicine, Division of Internal Medicine, University of Colorado School of Medicine, Aurora, CO; 2Department of Medicine, Division of Cardiology, University of Colorado School of Medicine, Aurora, CO; 3Department of Medicine, Center for Women's Health Research, University of Colorado School of Medicine, Aurora, CO; 4Division of Endocrinology, University of Colorado School of Medicine, Aurora, CO; 5Department of Medicine, Division of Cardiology, National Jewish Health, Denver, CO; and 6Denver Veterans Affairs Medical Center, Denver, CO
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Poitras VJ, Bentley RF, Hopkins-Rosseel DH, LaHaye SA, Tschakovsky ME. Lack of independent effect of type 2 diabetes beyond characteristic comorbidities and medications on small muscle mass exercising muscle blood flow and exercise tolerance. Physiol Rep 2015; 3:3/8/e12487. [PMID: 26265750 PMCID: PMC4562573 DOI: 10.14814/phy2.12487] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Persons with type 2 diabetes (T2D) are believed to have reduced exercise tolerance; this may be partly due to impaired exercising muscle blood flow (MBF). Whether there is an impact of T2D on exercising MBF within the typical constellation of comorbidities (hypertension, dyslipidemia, obesity) and their associated medications has not been investigated. We tested the hypothesis that small muscle mass exercise tolerance is reduced in persons with T2D versus Controls (matched for age, body mass index, fitness, comorbidities, non-T2D medications) and that this is related to blunted MBF. Eight persons with T2D and eight controls completed a forearm critical force (fCFimpulse) test as a measure of exercise tolerance (10-min intermittent maximal effort forearm contractions; the average contraction impulse in the last 30 sec quantified fCFimpulse). Forearm blood flow (FBF; ultrasound) and mean arterial pressure (MAP; finger photoplethysmography) were measured; forearm vascular conductance (FVK) was calculated. Data are means ± SD, T2D versus Control. fCFimpulse was not different between groups (136.9 ± 47.3 N·sec vs. 163.1 ± 49.7 N·sec, P = 0.371) nor was the ΔFBF from rest to during exercise at fCFimpulse (502.9 ± 144.6 vs. 709.1 ± 289.2 mL/min, P = 0.092), or its determinants ΔFVK and ΔMAP (both P > 0.05), although there was considerable interindividual variability. ΔFBF was strongly related to fCFimpulse (r = 0.727, P = 0.002), providing support for the relationship between oxygen delivery and exercise tolerance. We conclude that small muscle mass exercising MBF and exercise tolerance are not impaired in representative persons with T2D versus appropriately matched controls. This suggests that peripheral vascular control impairment does not contribute to reduced exercise tolerance in this population.
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Affiliation(s)
- Veronica J Poitras
- School of Kinesiology and Health Studies, Queen's University, Kingston, Ontario, Canada
| | - Robert F Bentley
- School of Kinesiology and Health Studies, Queen's University, Kingston, Ontario, Canada
| | - Diana H Hopkins-Rosseel
- Cardiac Rehabilitation Centre, Hotel Dieu Hospital, Kingston, Ontario, Canada School of Rehabilitation Therapy, Queen's University, Kingston, Ontario, Canada
| | - Stephen A LaHaye
- Cardiac Rehabilitation Centre, Hotel Dieu Hospital, Kingston, Ontario, Canada
| | - Michael E Tschakovsky
- School of Kinesiology and Health Studies, Queen's University, Kingston, Ontario, Canada
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Sacre JW, Jellis CL, Haluska BA, Jenkins C, Coombes JS, Marwick TH, Keske MA. Association of Exercise Intolerance in Type 2 Diabetes With Skeletal Muscle Blood Flow Reserve. JACC Cardiovasc Imaging 2015; 8:913-21. [PMID: 26189114 DOI: 10.1016/j.jcmg.2014.12.033] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Revised: 10/17/2014] [Accepted: 12/05/2014] [Indexed: 11/15/2022]
Abstract
OBJECTIVES This study sought to investigate the association of exercise intolerance in type 2 diabetes (T2DM) with skeletal muscle capillary blood flow (CBF) reserve. BACKGROUND Exercise intolerance in T2DM strongly predicts adverse prognosis, but associations with muscle blood flow independent of cardiac dysfunction are undefined. METHODS In 134 T2DM patients without cardiovascular disease, left ventricular function and contrast-enhanced ultrasound of the quadriceps (for CBF; i.e., product of capillary blood volume and velocity) were assessed at rest and immediately following treadmill exercise for peak oxygen uptake (Vo2peak). Left ventricular systolic and diastolic functional reserve indexes were derived from changes in systolic and early diastolic color tissue Doppler velocities. Cardiac index reserve and its constituents (stroke volume and chronotropic indexes) and left ventricular filling pressure (ratio of early diastolic mitral inflow and annular velocities) were also measured. RESULTS Vo2peak correlated with muscle CBF reserve (β = 0.16, p = 0.005) independent of cardiac index reserve and clinical covariates. This was explained by higher muscle capillary blood velocity reserve (β = 0.18, p = 0.002), rather than blood volume reserve (p > 0.10) in patients with higher Vo2peak. A concurrent association of Vo2peak with cardiac index reserve (β = 0.20, p < 0.001) appeared to reflect chronotropic index (β = 0.15, p = 0.012) rather than stroke volume index reserve (p > 0.10), although the systolic functional reserve index was also identified as an independent correlate (β = 0.16, p = 0.028). No associations of Vo2peak with diastolic functional reserve were identified (p > 0.10). CONCLUSIONS Vo2peak is associated with muscle CBF reserve in T2DM, independent of parallel associations with cardiac functional reserve. This is consistent with a multifactorial basis for exercise intolerance in T2DM.
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Affiliation(s)
- Julian W Sacre
- School of Human Movement and Nutrition Sciences, University of Queensland, Brisbane, Australia; Baker IDI Heart and Diabetes Institute, Melbourne, Australia
| | | | - Brian A Haluska
- School of Medicine, University of Queensland, Brisbane, Australia
| | - Carly Jenkins
- School of Medicine, University of Queensland, Brisbane, Australia
| | - Jeff S Coombes
- School of Human Movement and Nutrition Sciences, University of Queensland, Brisbane, Australia
| | - Thomas H Marwick
- School of Medicine, University of Queensland, Brisbane, Australia; Menzies Research Institute Tasmania, University of Tasmania, Hobart, Australia.
| | - Michelle A Keske
- Menzies Research Institute Tasmania, University of Tasmania, Hobart, Australia
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Poitras VJ, Bentley RF, Hopkins-Rosseel DH, LaHaye SA, Tschakovsky ME. Independent effect of type 2 diabetes beyond characteristic comorbidities and medications on immediate but not continued knee extensor exercise hyperemia. J Appl Physiol (1985) 2015; 119:202-12. [PMID: 26048976 DOI: 10.1152/japplphysiol.00758.2014] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2014] [Accepted: 06/01/2015] [Indexed: 01/23/2023] Open
Abstract
We tested the hypothesis that type 2 diabetes (T2D), when present in the characteristic constellation of comorbidities (obesity, hypertension, dyslipidemia) and medications, slows the dynamic adjustment of exercising muscle perfusion and blunts the steady state relative to that of controls matched for age, body mass index, fitness, comorbidities, and non-T2D medications. Thirteen persons with T2D and 11 who served as controls performed rhythmic single-leg isometric quadriceps exercise (rest-to-6 kg and 6-to-12 kg transitions, 5 min at each intensity). Measurements included leg blood flow (LBF, femoral artery ultrasound), mean arterial pressure (MAP, finger photoplethysmography), and leg vascular conductance (LVK, calculated). Dynamics were quantified using mean response time (MRT). Measures of amplitude were also used to compare response adjustment: the change from baseline to 1) the peak initial response (greatest 1-s average in the first 10 s; ΔLBFPIR, ΔLVKPIR) and 2) the on-transient (average from curve fit at 15, 45, and 75 s; ΔLBFON, ΔLVKON). ΔLBFPIR was significantly blunted in T2D vs. control individuals (P = 0.037); this was due to a tendency for reduced ΔLVKPIR (P = 0.063). In contrast, the overall response speed was not different between groups (MRT P = 0.856, ΔLBFON P = 0.150) nor was the change from baseline to steady state (P = 0.204). ΔLBFPIR, ΔLBFON, and LBF MRT did not differ between rest-to-6 kg and 6-to-12 kg workload transitions (all P > 0.05). Despite a transient amplitude impairment at the onset of exercise, there is no robust or consistent effect of T2D on top of the comorbidities and medications typical of this population on the overall dynamic adjustment of LBF, or the steady-state levels achieved during low- or moderate-intensity exercise.
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Affiliation(s)
- Veronica J Poitras
- School of Kinesiology and Health Studies, Queen's University, Kingston, Ontario, Canada
| | - Robert F Bentley
- School of Kinesiology and Health Studies, Queen's University, Kingston, Ontario, Canada
| | - Diana H Hopkins-Rosseel
- Cardiac Rehabilitation Centre, Hotel Dieu Hospital, Kingston, Ontario, Canada; and School of Rehabilitation Therapy, Queen's University, Kingston, Ontario, Canada
| | - Stephen A LaHaye
- Cardiac Rehabilitation Centre, Hotel Dieu Hospital, Kingston, Ontario, Canada; and
| | - Michael E Tschakovsky
- School of Kinesiology and Health Studies, Queen's University, Kingston, Ontario, Canada;
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Bender SB, Laughlin MH. Modulation of endothelial cell phenotype by physical activity: impact on obesity-related endothelial dysfunction. Am J Physiol Heart Circ Physiol 2015; 309:H1-8. [PMID: 25934096 DOI: 10.1152/ajpheart.00177.2015] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Accepted: 04/28/2015] [Indexed: 01/26/2023]
Abstract
Increased levels of physical activity are associated with reduced cardiovascular disease (CVD) risk and mortality in obesity and diabetes. Available evidence suggests that local factors, including local hemodynamics, account for a significant portion of this CVD protection, and numerous studies have interrogated the therapeutic benefit of physical activity/exercise training in CVD. Less well established is whether basal differences in endothelial cell phenotype between/among vasculatures related to muscle recruitment patterns during activity may account for reports of nonuniform development of endothelial dysfunction in obesity. This is the focus of this review. We highlight recent work exploring the vulnerability of two distinct vasculatures with established differences in endothelial cell phenotype. Specifically, based largely on dramatic differences in underlying hemodynamics, arteries perfusing soleus muscle (slow-twitch muscle fibers) and those perfusing gastrocnemius muscle (fast-twitch muscle fibers) in the rat exhibit an exercise training-like versus an untrained endothelial cell phenotype, respectively. In the context of obesity, therefore, arteries to soleus muscle exhibit protection from endothelial dysfunction compared with vulnerable arteries to gastrocnemius muscle. This disparate vulnerability is consistent with numerous animal and human studies, demonstrating increased skeletal muscle blood flow heterogeneity in obesity coincident with reduced muscle function and exercise intolerance. Mechanistically, we highlight emerging areas of inquiry exploring novel aspects of hemodynamic-sensitive signaling in endothelial cells and the time course of physical activity-associated endothelial adaptations. Lastly, further exploration needs to consider the impact of endothelial heterogeneity on the development of endothelial dysfunction because endothelial dysfunction independently predicts CVD events.
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Affiliation(s)
- Shawn B Bender
- Research, Harry S Truman Memorial Veterans Hospital, Columbia, Missouri; Department of Biomedical Sciences, University of Missouri, Columbia, Missouri; Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri; and
| | - M Harold Laughlin
- Department of Biomedical Sciences, University of Missouri, Columbia, Missouri; Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri; and Department of Medical Pharmacology and Physiology, University of Missouri School of Medicine, Columbia, Missouri
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15
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Blood supply classification and varied clinical manifestations of skeletal muscle infarction. Ann Plast Surg 2015; 74 Suppl 2:S109-12. [PMID: 25664416 DOI: 10.1097/sap.0000000000000461] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Muscle infarction is a rare complication of spontaneous ischemic necrosis occurring in skeletal muscle. It is particularly common in patients with diabetes who have impaired sugar regulation. However, muscle infarction is frequently misdiagnosed due to varied clinical manifestations. METHODS We presented 3 cases of muscle infarction reported during April 2009 to April 2014. After a comprehensive literature review, we selected 147 muscle infarction cases from the literature, first investigating the relationships between type of muscle blood supply and infarcted muscle. RESULTS The result indicated that muscle infarction 25.85% belonged to type I vascular supply and 61.21% belonged to type II vascular supply, according to the definition by Mathes and Nahai. CONCLUSIONS Poor glucose regulation, intense exercise without adequate hydration, vascular disease, and type I and II muscular blood supply were critical predisposing factors. For preventing muscle infarction, we recommend strict glucose regulation and a gradual increase in exercise with adequate hydration.
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Jegdic V, Roncevic Z, Skrabic V. Physical fitness in children with type 1 diabetes measured with six-minute walk test. Int J Endocrinol 2013; 2013:190454. [PMID: 23935617 PMCID: PMC3712235 DOI: 10.1155/2013/190454] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/24/2013] [Revised: 06/12/2013] [Accepted: 06/13/2013] [Indexed: 11/18/2022] Open
Abstract
Aim/Hypothesis. To examine whether children with DMT1 are less physically fit than healthy children and to assess whether an elevated level of HbA1c was associated with decreased physical fitness among children with diabetes. Methods. The study was conducted using case-control methodology. The cases were 100 children with T1DM, 7-17,9 years. Study subjects underwent a 6MWT, where distance measured, heart rate, and oxygen saturation was recorded. Results. Results of the 6MWT for children with T1DM and controls were 601.3 ± 86.1 meters versus 672.1 ± 60.6 meters, respectively (P < 0.001). The cases were divided into two subgroups, one with HbA1c levels >8% and one with HbA1c <8%. Results for both groups were inferior to the controls (P < 0.001). The posttest pulse rate in all subjects was higher than the pretest pulse rate (P < 0.001). Pulse oxygen levels were lower than controls at the pretest measurement (P < 0.001), and for both cases and controls, pulse oxygen levels decreased after test (P = 0.004). However, the change in oxygen saturation did not differ between the groups (P = 0.332). Conclusions. Children with T1D are less fit than matched controls. The level of HbA1c did not affect the physical fitness of children with T1D.
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Affiliation(s)
- Vladimir Jegdic
- Department of Pediatrics, University Hospital, 88000 Mostar, Bosnia and Herzegovina
| | - Zeljko Roncevic
- Department of Pediatrics, University Hospital, 88000 Mostar, Bosnia and Herzegovina
| | - Veselin Skrabic
- Department of Pediatrics, University Hospital, 21000 Split, Croatia
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Abstract
Limitations in physical fitness, a consistent finding in individuals with both type I and type 2 diabetes mellitus, correlate strongly with cardiovascular and all-cause mortality. These limitations may significantly contribute to the persistent excess cardiovascular mortality affecting this group. Exercise impairments in VO2 peak and VO2 kinetics manifest early on in diabetes, even with good glycemic control and in the absence of clinically apparent complications. Subclinical cardiac dysfunction is often present but does not fully explain the observed defect in exercise capacity in persons with diabetes. In part, the cardiac limitations are secondary to decreased perfusion with exercise challenge. This is a reversible defect. Similarly, in the skeletal muscle, impairments in nutritive blood flow correlate with slowed (or inefficient) exercise kinetics and decreased exercise capacity. Several correlations highlight the likelihood of endothelial-specific impairments as mediators of exercise dysfunction in diabetes, including insulin resistance, endothelial dysfunction, decreased myocardial perfusion, slowed tissue hemoglobin oxygen saturation, and impairment in mitochondrial function. Both exercise training and therapies targeted at improving insulin sensitivity and endothelial function improve physical fitness in subjects with type 2 diabetes. Optimization of exercise functions in people with diabetes has implications for diabetes prevention and reductions in mortality risk. Understanding the molecular details of endothelial dysfunction in diabetes may provide specific therapeutic targets for the remediation of this defect. Rat models to test this hypothesis are under study.
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Affiliation(s)
- Jane E B Reusch
- Denver VA Medical Center, Clermont Street, Denver, CO 80220, USA.
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18
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Gusso S, Pinto TE, Baldi JC, Robinson E, Cutfield WS, Hofman PL. Diastolic function is reduced in adolescents with type 1 diabetes in response to exercise. Diabetes Care 2012; 35:2089-94. [PMID: 22773700 PMCID: PMC3447841 DOI: 10.2337/dc11-2331] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
OBJECTIVE To determine whether adolescents with type 1 diabetes have left ventricular functional changes at rest and during acute exercise and whether these changes are affected by metabolic control and diabetes duration. RESEARCH DESIGN AND METHODS The study evaluated 53 adolescents with type 1 diabetes and 22 control adolescents. Baseline data included peak exercise capacity and body composition by dual-energy X-ray absorptiometry. Left ventricular functional parameters were obtained at rest and during acute exercise using magnetic resonance imaging. RESULTS Compared with nondiabetic control subjects, adolescents with type 1 diabetes had lower exercise capacity (44.7 ± 09 vs. 48.5 ± 1.4 mL/kg fat-free mass [FFM]/min; P < 0.05). Stroke volume was reduced in the diabetes group at rest (1.86 ± 0.04 vs. 2.05 ± 0.07 mL/kg FFM; P = 0.02) and during acute exercise (1.89 ± 0.04 vs. 2.17 ± 0.06 mL/kg FFM; P = 0.01). Diabetic adolescents also had reduced end-diastolic volume at rest (2.94 ± 0.06 vs. 3.26 ± 0.09 mL/kg FFM; P = 0.01) and during acute exercise (2.78 ± 0.05 vs. 3.09 ± 0.08 mL/kg FFM; P = 0.01). End-systolic volume was lower in the diabetic group at rest (1.08 ± 0.03 vs. 1.21 ± 0.04 mL/kg FFM; P = 0.01) but not during acute exercise. Exercise capacity and resting and exercise stroke volumes were correlated with glycemic control but not with diabetes duration. CONCLUSIONS Adolescents with type 1 diabetes have reduced exercise capacity and display alterations in cardiac function compared with nondiabetic control subjects, associated with reduced stroke volume during exercise.
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Affiliation(s)
- Silmara Gusso
- Liggins Institute, University of Auckland, Auckland, New Zealand.
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19
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Optical Spectroscopy and Multivariate Analysis for Biodosimetry and Monitoring of Radiation Injury to the Skin. Drug Dev Res 2012. [DOI: 10.1002/ddr.21021] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Sacre JW, Holland DJ, Jenkins C, Sharman JE. Augmentation index immediately after maximal exercise in patients with type 2 diabetes mellitus. Med Sci Sports Exerc 2012; 44:75-83. [PMID: 21685818 DOI: 10.1249/mss.0b013e318228588c] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
INTRODUCTION Patients with type 2 diabetes mellitus (T2DM) have exaggerated brachial and central (ascending aortic) blood pressure (BP) during exercise, which is associated with adverse outcomes. Central systolic loading, represented by the augmentation index (AIx), may contribute to exaggerated exercise central BP. This study sought to compare the central AIx response to peak exercise in T2DM and control patients and to identify mechanisms of altered exercise central AIx. METHODS Central BP and AIx were quantified by radial tonometry at rest and immediately after peak treadmill exercise in 106 patients with T2DM and 106 nondiabetic controls, pair-matched by age, gender, peak exercise brachial BP, and postexercise HR corresponding to tonometry acquisition. Cardiac volumes (by echocardiography) were assessed in a subgroup (22 T2DM and 22 controls) to derive rest and postexercise arterial-ventricular coupling parameters, including cardiac index (stroke volume index × HR), peripheral vascular resistance index (cardiac index / mean BP), and effective arterial elastance index (end-systolic pressure / stroke volume index). Reserve parameters (exercise--rest) were also defined. RESULTS Patients with T2DM had lower postexercise central AIx (-1% ± 13% vs 3% ± 14%, P = 0.038) and greater central AIx reserve (-24% ± 13% vs -20% ± 11%, P = 0.002) compared with controls, despite raised postexercise peripheral vascular resistance index (P = 0.013) and effective arterial elastance index (P = 0.011); these parameters independently predicted higher central AIx at rest (P < 0.01) but not after exercise. Moreover, T2DM was independently associated with lower postexercise central AIx (β = -0.21, P = 0.006). Cardiac index reserve, which was blunted in T2DM (P = 0.004), represented the only independent correlate of central AIx reserve (r = 0.39, P = 0.01). CONCLUSIONS Patients with T2DM have significantly (and paradoxically) lower postexercise central AIx and greater central AIx reserve, which may be explained by an impaired cardiac functional reserve.
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Affiliation(s)
- Julian W Sacre
- School of Medicine, The University of Queensland, Brisbane, Australia
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Inappropriately high left ventricular mass in patients with type 2 diabetes mellitus and no overt cardiac disease. The DYDA study. J Hypertens 2011; 29:1994-2003. [DOI: 10.1097/hjh.0b013e32834acc6d] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Abstract
OBJECTIVE To review the current research of new emerging diagnostic technology for non-invasive physiological monitoring of exercise and fitness. As a personal trainer, I believe that exercise can improve the conditions of several diseases and/or events such as stroke, post-traumatic head injury, spinal cord injury, and a multitude of other diseases. This compilation of information will allow health care providers tools of a non-invasive manner to promote healing and health that go beyond the initial event. Allowing patients continued managed care beyond what is believed to be their plateau. MATERIAL AND METHOD Review science-based research involving non-invasive technology, including cardiovascular evaluations: heart rate monitors, near-infrared spectroscopy, blood pressure, and electrocardiography; motor capabilities: surface electromyography and manual testers, i.e. dynamometer, and digital and video photography; radiological monitoring: magnetic resonance imaging, three-dimensional computer tomography, and laser Doppler. RESULTS This investigation has found that a new approach should be implemented for non-invasive physiological monitoring of exercise and fitness through development and utilization across a wide variety of equipment, and monitoring technology. This non-invasive methodology will not only motivate but encourage individuals to begin and remain compliant with an exercise program allowing a variety of health care providers to assist in patient care. DISCUSSION We need to shift the paradigm from taking care of the sick to maintaining the health of our patients. This can be accomplished with non-invasive evaluation, tracking, and monitoring tools. Many of the suggestions for monitoring are used in a clinical setting rather than a general fitness environment. These monitoring tests need to be economical as well as available for continual re-evaluation.
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VanHoose L, Sawers Y, Loganathan R, Vacek JL, Stehno-Bittel L, Novikova L, Al-Jarrah M, Smirnova IV. Electrocardiographic changes with the onset of diabetes and the impact of aerobic exercise training in the Zucker Diabetic Fatty (ZDF) rat. Cardiovasc Diabetol 2010; 9:56. [PMID: 20860788 PMCID: PMC2954909 DOI: 10.1186/1475-2840-9-56] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/05/2010] [Accepted: 09/22/2010] [Indexed: 01/01/2023] Open
Abstract
Background Early markers of diabetic autonomic neuropathy (DAN) in an electrocardiogram (ECG) include elevated R wave amplitudes, widening of QTc intervals and decreased heart rate variability (HRV). The severity of DAN has a direct relationship with mortality risk. Aerobic exercise training is a common recommendation for the delay and possible reversal of cardiac dysfunction. Limited research exists on ECG measures for the evaluation of aerobic exercise training in Zucker Diabetic Fatty (ZDF) rat, a model of type 2 diabetes. The objective of this study was to assess whether aerobic exercise training may attenuate diabetes induced ECG changes. Methods Male ZDF (obese fa/fa) and control Zucker (lean fa/+) rats were assigned to 4 groups: sedentary control (SC), sedentary diabetic (SD), exercised control (EC) and exercised diabetic (ED). The exercised groups began 7 weeks of treadmill training after the development of diabetes in the ED group. Baseline (prior to the training) and termination measurements included body weight, heart weight, blood glucose and glycated hemoglobin levels and ECG parameters. One way repeated measures ANOVA (group) analyzed within and between subject differences and interactions. Pearson coefficients and descriptive statistics described variable relationships and animal characteristics. Results Diabetes caused crucial changes in R wave amplitudes (p < 0.001), heart rate variability (p < 0.01), QT intervals (p < 0.001) and QTc intervals (p < 0.001). R wave amplitude augmentation in SD rats from baseline to termination was ameliorated by exercise, resulting in R wave amplitude changes in ED animals similar to control rats. Aerobic exercise training neither attenuated QT or QTc interval prolongation nor restored decreases in HRV in diabetic rats. Conclusion This study revealed alterations in R wave amplitudes, HRV, QT and QTc intervals in ZDF rats. Of these changes, aerobic exercise training was able to correct R wave amplitude changes. In addition, exercise has beneficial effect in this diabetic rat model in regards to ECG correlates of left ventricular mass.
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Affiliation(s)
- Lisa VanHoose
- Department of Physical Therapy and Rehabilitation Science, University of Kansas Medical Center, MS 2002, 3901 Rainbow Blvd, Kansas City, KS 66160, USA
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