Exercise-Derived Microvesicles: A Review of the Literature

Initially suggested as simple cell debris, cell-derived microvesicles (MVs) have now gained acceptance as recognized players in cellular communication and physiology. Shed by most, and perhaps all, human cells, these tiny lipid-membrane vesicles carry bioactive agents, such as proteins, lipids and microRNA from their cell source, and are produced under orchestrated events in response to a myriad of stimuli. Physical exercise introduces systemic physiological challenges capable of acutely disrupting cell homeostasis and stimulating the release of MVs into the circulation. The novel and promising field of exercise-derived MVs is expanding quickly, and the following work provides a review of the influence of exercise on circulating MVs, considering both acute and chronic aspects of exercise and training. Potential effects of the MV response to exercise are highlighted and future directions suggested as exercise and sports sciences extend the realm of extracellular vesicles

Whole-body heat stress and exercise stimulate the appearance of platelet microvesicles in plasma with limited influence of vascular shear stress

Intense, large muscle mass exercise increases circulating microvesicles, but our understanding of microvesicle dynamics and mechanisms inducing their release remains limited. However, increased vascular shear stress is generally thought to be involved. Here, we manipulated exercise-independent and exercise-dependent shear stress using systemic heat stress with localized single-leg cooling (low shear) followed by single-leg knee extensor exercise with the cooled or heated leg (Study 1, n = 8) and whole-body passive heat stress followed by cycling (Study 2, n = 8). We quantified femoral artery shear rates (SRs) and arterial and venous platelet microvesicles (PMV-CD41+) and endothelial microvesicles (EMV-CD62E+). In Study 1, mild passive heat stress while one leg remained cooled did not affect [microvesicle] (P ≥ 0.05). Single-leg knee extensor exercise increased active leg SRs by ~12-fold and increased arterial and venous [PMVs] by two- to threefold, even in the nonexercising contralateral leg (P < 0.05). In Study 2, moderate whole-body passive heat stress increased arterial [PMV] compared with baseline (mean±SE, from 19.9 ± 1.5 to 35.5 ± 5.4 PMV.μL-1.103, P < 0.05), and cycling with heat stress increased [PMV] further in the venous circulation (from 27.5 ± 2.2 at baseline to 57.5 ± 7.2 PMV.μL-1.103 during cycling with heat stress, P < 0.05), with a tendency for increased appearance of PMV across exercising limbs. Taken together, these findings demonstrate that whole-body heat stress may increase arterial [PMV], and intense exercise engaging either large or small muscle mass promote PMV formation locally and systemically, with no influence upon [EMV]. Local shear stress, however, does not appear to be the major stimulus modulating PMV formation in healthy humans

Post-exercise cardiac autonomic and cardiovascular responses to heart rate-matched and work rate-matched hypoxic exercise

PURPOSE: This study investigated the effect of performing hypoxic exercise at the same heart rate (HR) or work rate (WR) as normoxic exercise on post-exercise autonomic and cardiovascular responses.METHODS: Thirteen men performed three interval-type exercise sessions (5*5-min; 1-min recovery): normoxic exercise at 80% of the WR at the first ventilatory threshold (N), hypoxic exercise (FiO2=14.2%) at the same WR as N (H-WR) and hypoxic exercise at the same HR as N (H-HR). Autonomic and cardiovascular assessments were conducted before and after exercise, both at rest and during active squat-stand manoeuvres (SS).RESULTS: Compared to N, H-WR elicited a higher HR response (83% vs 75%HRmax, p&lt;0.001) and H-HR a reduced exercise WR (-21.1\ub19.3%, p&lt;0.001). Cardiac parasympathetic indices were reduced 15min after exercise and recovered within 60min in N and H-HR, but not after H-WR (p&lt;0.05). H-WR altered cardiac baroreflex sensitivity (cBRS) both at rest and during SS (specifically in the control of blood pressure fall during standing phases) in the first 60min after the exercise bout (p&lt;0.05). Post-exercise hypotension (PEH) did not occur in H-HR (p&gt;0.05) but lasted longer in H-WR than in N (p&lt;0.05).CONCLUSIONS: Moderate HR-matched hypoxic exercise mimicked post-exercise autonomic responses of normoxic exercise without resulting in significant PEH. This may relate to the reduced WR and the limited associated mechanical/metabolic strain. Conversely, WR-matched hypoxic exercise impacted upon post-exercise autonomic and cardiovascular responses, delaying cardiac autonomic recovery, temporarily decreasing cBRS and evoking prolonged PEH

Prolonged low flow reduces reactive hyperemia and augments low flow mediated constriction in the brachial artery independent of the menstrual cycle

© 2013 Rakobowchuk et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.Non-invasive forearm ischemia-reperfusion injury and low flow induced vascular dysfunction models provide methods to evaluate vascular function. The role of oestrogen, an endogenous anti-oxidant on recovery from ischemia-reperfusion injury has not been evaluated nor has the impact of prolonged low flow on vascular function been established. Eight healthy women (33610 yr) attended the lab during the follicular, ovulatory and mid-luteal phases of their menstrual cycles. After 30 minutes of rest, brachial artery vascular function was assessed by ultrasound measurements of diameter changes during 5 minutes of forearm ischemia and 3 minutes after. Subsequently, a 20-minute forearm ischemia period was completed. Further, vascular function assessments were completed 15, 30 and 45 minutes into recovery. Flow-mediated dilation, lowflow-mediated constriction, and reactive hyperaemia proximal to the area of ischemia were determined. Flow-mediated dilation was reduced at 15 minutes of recovery but recovered at 30 and 45 minutes (PRE: 7.161.0%, POST15:4.560.6%, POST30:5. 560.7% POST45:5.960.4%, p,0.01). Conversely, low-flow mediated constriction increased (PRE: 21.360.4%, POST15: 23.360.6%, POST30: 22.560.5% POST45: 21.560.12%, p,0.01). Reactive hyperaemia was reduced throughout recovery (p,0.05). Data were unaffected by menstrual phase. Prolonged low flow altered vascular function and may relate as much to increased vasoconstriction as with decreased vasodilation. Reductions in anterograde shear and greater retrograde shear likely modulate the brachial artery response, but the reduced total shear also plays an important role. The data suggest substantial alterations in vascular function proximal to areas of ischemia with potential clinical implications following reperfusion.British Heart Foundation (PG/08/060/25340),a Physiological Society summer studentship to SG, and a Wellcome Trust Vacation Studentship to EP

Post-exercise hypotension and reduced cardiac baroreflex after half-marathon run: in men, but not in women

We examined whether trained women exhibit similar cardiovascular and cardiac baroreflex alterations after a half-marathon compared to men. Thirteen women (39.1 \ub1 9.3 years; 165 \ub1 6 cm; 58.2 \ub1 7.5 kg; maximal aerobic speed (MAS): 13.7 \ub1 2.2 km\ub7h-1) and 12 men (45.7 \ub1 10.5 years; 178 \ub1 7 cm; 75.0 \ub1 8.3 kg; MAS: 15.8 \ub1 2.2 km\ub7h-1) ran an official half-marathon. Before and 60-min after, cardiovascular variables, parasympathetic (heart rate variability analysis) modulation and cardiac baroreflex function (transfer function and sequence analyses) were assessed during supine rest and a squat-stand test. Running performance was slower in women than in men (120 \ub1 19 vs. 104 \ub1 14 min for women and men, respectively). However, when expressed as a percentage of MAS, it was similar (78.1 \ub1 4.6% and 78.2 \ub1 5.4% of MAS for women and men, respectively). Before the run, women exhibited lower mean blood pressure (BP), cardiac output (CO) and stroke volume (SV) compared to men, together with higher parasympathetic indexes. After the race, parasympathetic indexes decreased in both sexes, but remained higher in women. Reduced SV, systolic BP and cardiac baroreflex were observed in men but not in women. Contrary to men, a competitive half-marathon did not trigger post-exercise hypotension and a reduced cardiac baroreflex in women

Sprint interval and sprint continuous training increases circulating CD34+ cells and cardio-respiratory fitness in young healthy women

The improvement of vascular health in the exercising limb can be attained by sprint interval training (SIT). However, the effects on systemic vascular function and on circulating angiogenic cells (CACs) which may contribute to endothelial repair have not been investigated. Additionally, a comparison between SIT and sprint continuous training (SCT) which is less time committing has not been made

Moderate and heavy metabolic stress interval training improve arterial stiffness and heart rate dynamics in humans

Traditional continuous aerobic exercise training attenuates age-related increases of arterial stiffness, however, training studies have not determined whether metabolic stress impacts these favourable effects. Twenty untrained healthy participants (n = 11 heavy metabolic stress interval training, n = 9 moderate metabolic stress interval training) completed 6 weeks of moderate or heavy intensity interval training matched for total work and exercise duration. Carotid artery stiffness, blood pressure contour analysis, and linear and non-linear heart rate variability were assessed before and following training. Overall, carotid arterial stiffness was reduced (p  0.05). This study demonstrates the effectiveness of interval training at improving arterial stiffness and autonomic function, however, the metabolic stress was not a mediator of this effect. In addition, these changes were also independent of improvements in aerobic capacity, which were only induced by training that involved a high metabolic stress

1.3 Lectures in the Live Age

Flexibility in lecturing practice is sometimes a necessity for academics who must balance a research and teaching mandate. This becomes more of an issue when important conferences occur outside the summer semester. As professors, attending and presenting at conferences and ensuring undergraduate courses are of a high quality are the two most important aspects of the job. This year, invited talks and collaborative work required that I be off-campus and a lack of expertise within the department to “cover” lectures meant I needed to find a creative solution that provided an excellent educational experience, at a distance to my students. Delivering lectures using a traditional streaming service enables universities and other large businesses to deliver webinars to thousands of users but they often require proprietary software that are costly. Whereas more recently developed “live” streaming methods are now available to just about anyone with an internet connection. Popular options like Facebook Live enable simple broadcasting of captured video from portable devices like mobile phones. To broadcast lecture content, the providing a “Skype” lecture was also considered but the complexities of establishing a group video call with an entire class was logistically difficult thus a YouTube Live streaming option was selected. Using freely available webcasting software Wirecast, Moodle, and a YouTube subscription, I remotely delivered lectures in real-time, to students in human physiology. This seminar will focus on the requirements, opportunities and pitfalls that this method of content delivery offers