For example, during lung expansion inspiration , P RA can transiently fall by several mmHg, whereas the P V in the abdominal compartment may increase by a few mmHg. These changes result in a large increase in the pressure gradient driving venous return from the peripheral circulation to the right atrium.
Although the above relationship is true for the hemodynamic factors that determine the flow of blood from peripheral veins abdominal venous cava in the figure back to the right atrium of the heart, it is important not to lose sight of the fact that blood flow through the entire systemic circulation can be represented by either the cardiac output or the venous return, because these are equal in the steady-state owing to the circulatory system being closed.
Therefore, one could just as well say that venous return is determined by the mean aortic pressure minus the mean right atrial pressure, divided by the resistance of the entire systemic circulation i.
There is much confusion about the pressure gradient that determines venous return largely because of different conceptual models that are used to describe venous return. Furthermore, although transient differences occur between the flow of blood leaving cardiac output and entering the heart venous return , these differences when they occur cause adjustments that rapidly return in a new steady-state in which cardiac output flow out equals venous return flow in.
Increasing the amount of oxygenated blood to be delivered to the muscles provides them with an increase in energy for the event that is about to take place. Increasing venous return also increases muscle temperature. Increasing muscle temperature allows muscles to loosen to reduce tightness and increase in range of movement.
Increasing range of movement is essential pre event as it reduces the chances of injury during short bursts of movement. Stress can be reduced when venous return is increased. Stress can be shown both physically and mentally. When venous return increases and helps to reduce muscle tightness, stress within muscles is also reduced allowing them to relax. Allowing muscles to relax also decreases pain. Decreasing pain can help reduce stress mentally as a person is able to mentally relax without the irritation of tight, tense muscles.
Increased venous return can help post surgery. Surgery can leave damaging effects on a person's body. Increasing venous return encourages a more efficient circulation to help provide injury sites with an increase in oxygen and nutrients, essential for the repair of damaged tissues and cells. Increased venous return can also help reduce muscle tightness and tension that has occurred as a result of surgery.
Tightness and tension can increase pain and irritation for a person. As an increase in blood is delivered to muscles, their temperature rises allowing their elasticity and flexibility to also increase. Increasing muscle tissue elasticity and flexibility helps to reduce tightness and tension which helps to reduce pain therefore relieving some of the symptoms caused by surgery.
Venous return is the rate of blood flow back to the heart. Increased venous return has many benefits including increased relaxation, reduced tension and increased vasodilation. Many techniques including deep strokes, lymphatic drainage and effleurage are used to increase venous return and help pre event, stress and post surgery. The easiest way to arrange a sports massage at Physio. We have immediate appointments available today. Contact us to make an appointment. Our clinics are open: Mon - Fri: 8am - 8pm Saturday: 9am - 5pm Sunday: 9am - 4pm.
Contact Clinics Search Menu. Contact us Our Clinics Search. Skip navigation. Book now. Our Clinics. This post-exercise blood flow distribution may contribute to orthostatic hypotension, expected to be further exacerbated by the presence of skin thermoregulatory perfusion. While a majority of the literature commenting on changes in post-exercise perfusion focus on cold water immersion, earlier reports utilized the simple application of an ice bag and yet still demonstrated attenuation of acute post-exercise perfusion elevation and edema compared to a non-cooled control limb Yanagisawa et al.
Similarly, whole-body CWI is capable of reducing post-exercise femoral vein diameter Peiffer et al. Overall, elevated skeletal muscle temperature and skin perfusion following exercise in the heat contribute to a reduction in central venous pressure and a failure of TPR to increase appropriately with upright posture, leading to orthostatic intolerance.
Cooling countermeasures appear to reduce both cutaneous and muscle blood flow to elicit a redistribution from the periphery to the thoracic vasculature at least when exercise is performed in thermoneutral conditions.
Limited research has indicated that a reduction in large skeletal muscle microvascular perfusion following heated exercise is possible, although it appears to be smaller in magnitude than those changes seen following exercise performed in neutral ambient conditions. To improve our understanding of the influence of cooling countermeasures to prevent cardiovascular adjustments causing orthostatic intolerance, investigations examining the extent muscle and cutaneous vascular responsiveness may be blunted in response to varied cold stimuli following exercise performed in the heat are both warranted and necessary.
Furthermore, it should be acknowledged that redistribution of cutaneous blood flow centrally could influence the degree of heat dissipation from the skin in a post-exercise setting. However, with a significantly widened thermal gradient elicited by skin surface cooling combined with a large preexisting degree of cutaneous vasodilation due to increased body temperatures, meaningful reductions in heat dissipation from the skin are likely minimal.
Very few studies have specifically evaluated post-exercise cerebral blood flow modulation resultant from post-exercise cooling strategies. Post-exercise cooling may offset reductions in central venous pressure that would otherwise contribute to reductions in cerebral blood flow, reducing the risk of orthostatic intolerance. In contrast, other literature indicates that CWI may further reduce a pre-frontal lobe NIRS-measured index of cerebral blood volume and oxygenation following heated high-intensity exercise Minett et al.
Because reduced cerebral blood flow velocity is strongly linked to orthostatic intolerance Novak, and methodological considerations limit the interpretation of specific regional blood volume quantifications, it is likely that post-exercise cooling efforts are capable of augmenting cerebral perfusion and consequently reducing the likelihood of orthostatic intolerance.
Still, further investigation of skin surface cooling vs. The ability of water immersion to increase central venous pressure via a shift of peripheral blood into the thoracic vasculature simultaneously stimulates high arterial pressure and low cardiopulmonary pressure baroreflexes Pump et al.
Water temperature appears to play a key role in the effectiveness of water immersion to influence parasympathetic reactivation. Several reports implicate cold water immersion post-exercise as a greater modulator of cardiac parasympathetic reactivation compared to neutral or warm water immersions, both when exercise is performed in thermoneutral Al Haddad et al.
Importantly, the limitations of HRV are discussed earlier in this review and as such future use of HRV to assess post-exercise cooling responses are best used and interpreted in conjunction with more directly mechanistic measurements. Successful orthostatic tolerance requires appropriate baroreflex responses to upright posture.
During and after exercise in the heat, the ability of the baroreflex to cause vasoconstriction necessary to defend mean arterial pressure is limited by cutaneous vasodilation, elevated tissue temperature and peripheral venous pooling.
Post-exercise cooling, especially cold water immersion, appears to augment both mean arterial pressure and cerebral vascular perfusion to minimize or prevent orthostatic intolerance after exercise in the heat Figure 1. Still, the uniform skin temperatures created by the use of a water-perfused suit in many of the research investigations discussed within this review limit real-world applicability.
Therefore, more research is necessary to further understand and optimize real-world approaches to post-exercise cooling to definitively improve orthostatic tolerance and minimize injury. Optimal timing of cooling strategies before, during, or after exercise heat stress to effectively offset the development of OI should also be investigated, as proactive strategies may be safer and more logistically feasible than reactive strategies.
Lastly, continued evaluation of post-exercise cooling techniques specifically with women is necessary to determine the influence of estradiol and its fluctuations specifically on the cardiovascular adjustments that control skin perfusion. Figure 1. Post-exercise cooling cardiovascular adjustments to maintain orthostatic tolerance.
All authors designed and outlined the work, performed literature reviews and interpreted findings, and drafted and revised the manuscript. All authors approved the final version of the manuscript and agree to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.
All persons designated as authors qualify for authorship, and all those who qualify for authorship are listed. This article is approved for public release, and distribution is unlimited. Citations of commercial organizations and trade names in this report do not constitute an official Department of the Army endorsement or approval of the products or services of these organizations.
The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. Al Haddad, H. Effect of cold or thermoneutral water immersion on post-exercise heart rate recovery and heart rate variability indices. Bass, D. Responses of body fluid compartments to heat and cold. Bjurstedt, H. Orthostatic reactions during recovery from exhaustive exercise of short duration.
Acta Physiol. Boulant, J. Buchheit, M. Effect of cold water immersion on postexercise parasympathetic reactivation. Heart Circ. Castellani, J. Human physiological responses to cold exposure: acute responses and acclimatization to prolonged exposure. Charkoudian, N. Mechanisms and modifiers of reflex induced cutaneous vasodilation and vasoconstriction in humans. Sympathetic neural activity to the cardiovascular system: integrator of systemic physiology and interindividual characteristics.
Chen, C. Postexercise hypotension. Sport Sci. Choo, H. Effect of water immersion temperature on heart rate variability following exercise in the heat. Kinesiology 50, 67— Google Scholar. Claydon, V. Cardiovascular responses and postexercise hypotension after arm cycling exercise in subjects with spinal cord injury. Cui, J. Effect of skin surface cooling on central venous pressure during orthostatic challenge. The effect of different water immersion temperatures on post-exercise parasympathetic reactivation.
Deuster, P. Prolonged whole-body cold water immersion: fluid and ion shifts. Diaz, T. Draghici, A. The physiological basis and measurement of heart rate variability in humans. Durand, S. Skin surface cooling improves orthostatic tolerance in normothermic individuals. Franklin, P. The influence of thermoregulatory mechanisms on post-exercise hypotension in humans.
Fu, Q. Hemodynamics of orthostatic intolerance: implications for gender differences. Ganzeboom, K. Prevalence and triggers of syncope in medical students. The cardiovascular challenge of exercising in the heat. Halliwill, J. Mechanisms and Clinical implications of post-exercise hypotension in humans.
Sports Sci. Postexercise hypotension and sustained postexercise vasodilatation: what happens after we exercise? Effect of systemic nitric oxide synthase inhibition on postexercise hypotension in humans.
Harrison, M. The stroke volume increases because of increased ventricular contractility, manifested by an increased ejection fraction and mediated by sympathetic nerves to the ventricular myocardium.
End-diastolic volume increase slightly. Because of this increased filling, the Frank-Starling mechanism also contributes to the increased stroke volume stroke volume increases when end-diastolic volume increases. Cardiac output can be increased to high levels only if the peripheral processes favoring venous return to the heart are simultaneously activated to the same degree. Factor promoting venous return:. Control of sympathetic outflow.
One or more discrete control centers in the brain are activated by output from the cerebral cortex. These centers become activated before the exercise started.
Once exercise is started, local chemical changes in the muscle can develop, particularly during high levels of exercise, because of imperfect matching between blood flow and metabolic demands.
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