Circulating MicroRNA Responses to Postprandial Lipemia with or without Prior Exercise

Repeated exposure to a high-fat meal triggers inflammation and oxidative stress, contributing to the onset of cardiometabolic diseases. Regular exercise prevents cardiometabolic diseases and a prior bout of acute endurance exercise can counteract the detrimental cardiovascular effects of a subsequent high-fat meal. Circulating microRNAs (ci-miRs) are potential mediators of these vascular effects through regulation of gene expression at the posttranscriptional level. Therefore, we investigated the expression of ci-miRs related to vascular function (miR-21, miR-92a, miR-126, miR-146a, miR-150, miR-155, miR-181b, miR-221, miR-222) in plasma from healthy, recreationally to highly active, Caucasian adult men after a high-fat meal with (EX) and without (CON) a preceding bout of cycling exercise. Ci-miR-155 was the only ci-miR for which there was a significant interaction effect of high-fat meal and exercise (p=0.050). Ci-miR-155 significantly increased in the CON group at two (p=0.007) and four hours (p=0.010) after the high-fat meal test, whereas it significantly increased in the EX group only four hours after the meal (p=0.0004). There were significant main effects of the high-fat meal on ci-miR-21 (p=0.01), ci-miR-126 (p=0.02), ci-miR-146a (p=0.02), ci-miR-181b (p=0.02), and ci-miR-221 (p=0.008). Collectively, our results suggest that prior exercise does not prevent high-fat meal-induced increases in vascular-related ci-miRs.

Prior exercise impairs subsequent performance in an intensity- and duration-dependent manner

Prior constant-load exercise performed for 30-min at or above maximal lactate steady state (MLSSp) significantly impairs subsequent time-to-task failure (TTF) compared with TTF performed without prior exercise. We tested the hypothesis that TTF would decrease in relation to the intensity and the duration of prior exercise compared to a baseline TTF trial. Eleven individuals (6 men, 5 women, 28 ± 8 yrs) completed the following tests on a cycle ergometer (randomly assigned after MLSSp was determined): i) a ramp-incremental test, ii) a baseline TTF trial performed at 80% of peak power (TTFb), iii) five 30-min constant-PO rides at 5% below lactate threshold (LT-5%), halfway between LT and MLSSp (Delta50), 5% below MLSSp (MLSS-5%), MLSSp, and 5% above MLSSp (MLSS+5%), and iv) 15- and 45-min rides at MLSSp (MLSS15 and MLSS45, respectively). Each condition was immediately followed by a TTF trial at 80% of peak power. Compared to TTFb (330 ± 52s), there was 8.0 ± 24.1, 23.6 ± 20.2, 41.0 ± 14.8, 52.2 ± 18.9, and 75.4 ± 7.4% reduction in TTF following LT-5%, Delta50, MLSS-5%, MLSSp, and MLSS+5%, respectively. Following MLSS15 and MLSS45 there were 29.0 ± 20.1 and 69.4 ± 19.6% reductions in TTF, respectively (P <0.05). It is concluded that TTF is reduced following prior exercise of varying duration at MLSSp and at submaximal intensities below MLSS. Novelty: •Prior constant-PO exercise, performed at intensities below MLSSp, reduces subsequent TTF performance. •Subsequent TTF performance is reduced in a linear fashion following an increase in the duration of constant-PO exercise at MLSSp.

‘It’s like Going to the Regular Class but without Being there’: A Qualitative Analysis of Older people’s Experiences of Exercise in the Home during Covid-19 Lockdown in England

It is expected that the Covid-19 lockdown will have increased physical inactivity with negative impacts for older people, who are at greater risk of health complications from the virus. This paper draws on customer evaluation questionnaire of a Pilates class aimed at people aged over 50 years old, which transitioned from a studio setting to online classes via Zoom at the start of the lockdown in England. The paper aims to (i) evaluate the shift of exercise services to online and (ii) examine how engagement with online services has influenced people’s reaction to Covid-19 and unprecedented confinement to their homes. Our analysis shows that experiences of exercise in the home are dependent on prior exercise engagement, particularly a sense of progress and competency in exercise movements, trust in the instructor and socio-economic privileges that enable participants to love and appreciate their homes. This paper argues that online classes have had positive impact on participants’ ability to cope with lockdown: routine, structure and being seen by others all proved important well-being aspects.

Exercise alters LPS-induced glial activation in the mouse brain

Experimental and epidemiological evidence suggest that modifiable lifestyle factors, including physical exercise, can build structural and cognitive reserve in the brain, increasing resilience to injury and insult. Accordingly, exercise can reduce the increased expression of proinflammatory cytokines in the brain associated with ageing or experimentally induced neuroinflammation. However, the cellular mechanisms by which exercise exerts this effect are unknown, including the effects of exercise on classic or alternative activation of astrocytes and microglia. In the present study, we assess the effects of nine consecutive days of treadmill running on the glial cell response to a single systemic injection of lipopolysaccharide (LPS) and, in parallel, the effects on spatial learning and memory. We show that prior exercise protects against LPS-induced impairment of performance in the object displacement task concomitant with attenuation of IL-1β, TNFα and IL-10 mRNA expression in the hippocampus. Assessment of isolated astrocytes and microglia revealed that LPS induced a proinflammatory response in these cells that was not observed in cells prepared from the brains of mice who had undergone prior exercise. The results suggest that exercise modulates neuroinflammation by reducing the proinflammatory microglial response, suggesting a mechanism by which exercise may be neuroprotective.

The impact of preconditioning exercise on the vascular response to an oral glucose challenge

Exercise elicits direct benefits to insulin sensitivity but may also indirectly improve glucose uptake by hemodynamic conditioning of the vasculature. The purpose of this study was to examine the modifying effect of three different types of exercise on the vascular response to an oral glucose challenge. Twenty healthy adults (9 women, 11 men; 23±3 years old) completed a standard oral glucose tolerance test (OGTT) at rest, as well as 1.5 hours after moderate continuous cycling exercise (30 min; 65% V̇O2peak), high intensity interval cycling exercise (10x1 min at 90% heart rate peak), and lower-load higher-repetition resistance exercise (25-35 repetitions/set, 3 sets). Brachial and superficial femoral artery blood flow, conductance, and oscillatory shear index were measured throughout the OGTT. Regardless of rested state or exercise preconditioning, the OGTT induced reductions in brachial artery blood flow and conductance (p<0.001), and transient increases in brachial and superficial femoral artery oscillatory shear index and retrograde blood flow (p<0.01). Continuous cycling and resistance exercise were followed with a small degree of protection against prolonged periods of oscillatory flow. Our findings imply transient peripheral vasoconstriction and decreased limb blood flow during a standard OGTT, for which prior exercise was unable to prevent in healthy adults. NOVELTY BULLETS • We investigated the impact of continuous, interval, and resistance exercise on the hemodynamic response to an oral glucose tolerance test (OGTT). • Our findings suggest decreased upper-limb blood flow during an OGTT is not prevented by prior exercise in healthy adults.