The effect of rowing on endothelial function and insulin action in healthy controls and in patients with type 2 diabetes

The Time Course of Cardiorespiratory Adaptations to Rowing Indoor Training in Post-Menopausal Women

BACKGROUND

Post-menopausal women have impaired cardiorespiratory responses to exercise compared to young women. Exercise training may counterbalance impairments, but the time-dependent effects of exercise training remain unclear. The current study aims to investigate the effects of rowing training on maximal aerobic capacity and time-course cardiorespiratory adaptations in older women.

METHODS

Female participants (n = 23) were randomly allocated to the experimental group (EXP; n = 23; 66 ± 5 years old) enrolled in rowing exercise training and control group (CON; n = 10; 64 ± 4 years old). The cardiopulmonary exercise test (CET) was performed in a cycle ergometer pre- and post-interventions. Oxygen uptake (VO2), stroke volume (SV), cardiac output (CO), and HR were recorded during CET and analyzed at the peak of the exercise. HR was monitored during exercise recovery, and the index of HRR was calculated by ΔHRR (HRpeak-HR one-minute recovery). Every two weeks, Rowing Stepwise Exercise (RSE) in a rowing machine was performed to track specific adaptations to the exercise modality. HR was continuously recorded during RSE and corrected for the average power of each step (HR/watts). The rowing training protocol consisted of three weekly sessions of 30 min at an intensity corresponding to 60-80% of peak HR for ten weeks.

RESULTS

Rowing exercise training increased VO2, SV, and CO at the peak of the CET, and ΔHRR. Increased workload (W) and reduced HR response to a greater achieved workload (HR/W) during RSE were observed after six weeks of training.

CONCLUSIONS

Rowing exercise training is a feasible method to improve cardiorespiratory performance, vagal reactivation and heart rate adjustments to exercise in older women.

The Urgent Need for Recommending Physical Activity for the Management of Diabetes During and Beyond COVID-19 Outbreak

Diabetes is the second most prevalent non-communicable chronic diseases (NCDs) in patients with coronavirus disease 2019 (COVID-19) and is highly associated with increased incidence of disease severity and mortality. Individuals with diabetes and poor glycemic control have an even worse prognosis. Despite of the need/effectiveness of social distancing measures (i.e.: home confinement, quarantine and/or lockdown) during COVID-19 outbreak, preliminary findings showed an increase in negative behaviors during COVID-19 home confinement (i.e.: ~33.5% reduction in physical activity, ~28.6% (~3.10h) increase in sedentary behavior (i.e.: daily sitting, reclining and lying down time), and more unhealthy food consumption and meal pattern), which may have important clinical implications. For example, we estimated that this reduction in physical activity can increase the cases of type 2 diabetes (from ~7.2% to ~9.6%; ~11.1 million cases per year) and all-cause mortality (from ~9.4% to ~12.5%; ~1.7 million deaths per year) worldwide. Few weeks of reduction in physical activity levels result in deleterious effects on several cardiometabolic (i.e.: glycemic control, body composition, inflammatory cytokines, blood pressure, vascular function…) and functional parameters (i.e.: cardiorespiratory/muscle fitness, balance, agility…). In contrast, physical activity and exercise are important tools for preventing and treating diabetes and others NCDs. Home-based exercise programs are useful, safe and effective for the management of diabetes, and could be widely used during COVID-19 outbreak. In this context, there is an urgent need for recommending physical activity/exercise, during and beyond COVID-19 outbreak, for improving the management of diabetes, as well as to prevent the increase in global burden of COVID-19, diabetes and others NCDs.

The physiology of rowing with perspective on training and health

PURPOSE

This review presents a perspective on the expansive literature on rowing.

METHODS

The PubMed database was searched for the most relevant literature, while some information was obtained from books.

RESULTS

Following the life span of former rowers paved the way to advocate exercise for health promotion. Rowing involves almost all muscles during the stroke and competition requires a large oxygen uptake, which is challenged by the pulmonary diffusion capacity and restriction in blood flow to the muscles. Unique training adaptations allow for simultaneous engagement of the legs in the relatively slow movement of the rowing stroke that, therefore, involves primarily slow-twitch muscle fibres. Like other sport activities, rowing is associated with adaptation not only of the heart, including both increased internal diameters and myocardial size, but also skeletal muscles with hypertrophy of especially slow-twitch muscle fibres. The high metabolic requirement of intense rowing reduces blood pH and, thereby, arterial oxygen saturation decreases as arterial oxygen tension becomes affected.

CONCLUSION

Competitive rowing challenges most systems in the body including pulmonary function and circulatory control with implication for cerebral blood flow and neuromuscular activation. Thus, the physiology of rowing is complex, but it obviously favours large individuals with arms and legs that allow the development of a long stroke. Present inquiries include the development of an appropriately large cardiac output despite the Valsalva-like manoeuvre associated with the stroke, and the remarkable ability of the brain to maintain motor control and metabolism despite marked reductions in cerebral blood flow and oxygenation.

Comparing the Efficacy of Supervised and Unsupervised Exercise Training on Glycaemic Control in Type 2 Diabetes: A Systematic Review

BACKGROUND

Exercise training is vital for glycaemic control in patients with type 2 diabetes mellitus (T2D). While the positive effects of supervised exercise training are well established, unsupervised training may offer an alternative and more sustainable means of realising the benefits of exercise away from a resource-heavy supervised setting.

OBJECTIVE

To evaluate the available literature and compare the efficacy of supervised and unsupervised exercise training programs on glycemic control in patients with T2D.

METHODS

CINAHL, MEDLINE, PubMed, and EMBASE, searched from inception to 20 July 2018. Only studies that included both supervised and unsupervised training were included.

RESULTS

Four studies, involving 115 participants, were included. One compared supervised with unsupervised exercise training and three investigated the efficacy of unsupervised training following supervised training. While supervised training is effective for improving glycaemic control in patients with T2D, unsupervised training may not maintain these changes. Included studies lacked detail relating to the supervised and unsupervised training programs.

CONCLUSIONS

Given that exercise is a critical component for maintenance of glycaemic control in patients with T2D, and because unsupervised training has been shown to be effective in improving clinical outcomes in other disease populations, further research is warranted to compare supervised and unsupervised exercise training in patients with T2D. It is important that future studies report standardised and detailed descriptions of key elements that form the basis of supervised and unsupervised exercise training groups.

Resistance to diabetes-promoting lifestyle factors -- what is the mechanism?

Not all people exposed to diabetes-promoting lifestyle factors progress to overt type 2 diabetes. The emerging concept of hormesis provides an explanation for the resistance to metabolic stress. Hormesis requires limited stress or damage which elicits an adaptive repair and protective response which renders the organism resistant to further metabolic stress.

Resistance to type 2 diabetes mellitus: a matter of hormesis?

Type 2 diabetes mellitus is characterized by subclinical systemic inflammation and impaired regulation of blood glucose levels. Interestingly, impairment of glycemic control occurs despite substantial insulin secretion early in the course of this disease. Dysfunction of several organs (including pancreatic islets, liver, skeletal muscle, adipose tissue, gut, hypothalamus and the immune system) has been implicated in the pathogenesis of type 2 diabetes mellitus. However, diabetes-promoting lifestyle factors do not inevitably cause disease in all persons exposed. Hence, defense mechanisms must exist that can keep the detrimental influence of these risk factors at bay. Hormesis describes the phenomenon that exposure to a mild stressor confers resistance to subsequent, otherwise harmful, conditions of increased stress. This Review discusses the emerging concept that the effectiveness of an adaptive (hormetic) response to detrimental lifestyle factors determines the extent of protection from progression to type 2 diabetes mellitus. Further analysis of these protective hormetic responses at the molecular level should help to identify novel targets for preventive or therapeutic intervention in patients at risk of developing type 2 diabetes mellitus or those with overt disease.

Exercise attenuates the premature cardiovascular aging effects of type 2 diabetes mellitus

Type 2 diabetes mellitus (T2D) is an example of a disease process that results in decrements in function additional to those imposed by the inexorable 'primary aging' process. These decrements due to disease, rather than primary aging, can be termed 'secondary aging', and include the premature development (as early as adolescence) of asymptomatic preclinical cardiovascular abnormalities (e.g. endothelial dysfunction, arterial stiffness, diastolic dysfunction), as well as impaired exercise performance. These abnormalities are important, as they are associated with greater cardiovascular morbidity and mortality in people with and without T2D. A better understanding of the pathophysiology of secondary cardiovascular aging in people with T2D is warranted, and an evaluation of the benefits of existing treatments for these abnormalities is useful (e.g. exercise training). The focus of this review is to discuss the data relevant to the following key postulates: (a) T2D causes premature cardiovascular aging; (b) in contrast to primary cardiovascular aging, the premature cardiovascular aging of T2D may be modifiable with exercise. The exercise-focused perspective for this review is appropriate because impairments in exercise performance are markers of premature cardiovascular aging in T2D, and also because exercise training shows promise to attenuate some aspects of cardiovascular aging during the preclinical stage.

Endothelial function after 10 days of bed rest in individuals at risk for type 2 diabetes and cardiovascular disease

Physical inactivity is considered to be deleterious to vascular health, and in particular in first-degree relatives to patients with type 2 diabetes (FDR) and persons born with low birth weight (LBW), who may later in life develop cardiovascular disease. A period of imposed physical inactivity could unmask this risk. We hypothesized that the impact of physical inactivity on endothelial function would be more marked in subjects at increased risk for type 2 diabetes and cardiovascular disease (LBW and FDR) compared with a matched control group (CON), all of whom were recruited via advertisements and via the Danish Birth Registry. Twenty LBW, 20 CON and 13 FDR were studied before and after 10 days of bed rest. Forearm blood flow (FBF) was measured by venous occlusion plethysmography during brachial intra-arterial infusion of acetylcholine or adenosine at baseline and with superimposed hyperinsulinaemia. Markers of endothelial activation and inflammation were measured in plasma. Bed rest did not change the vasodilator responses to adenosine or acetylcholine alone in any group, but reduced vasodilator responses to adenosine or acetylcholine during hyperinsulinaemia in LBW. Bed rest impaired insulin-mediated vasodilatation in CON and LBW and increased endothelial activation markers in FDR and LBW but not in CON. Vasodilator responses were very low in FDR prior to bed rest, and did not decrease further during bed rest. Physical inactivity does not impair endothelium-dependent vasodilatation per se, but the vascular vasodilator effect of insulin diminished in CON and LBW after bed rest. In FDR, a further deterioration of FBF with inactivity is not possible.