Cognitive Deficits from COVID, “4-second” Workouts, and How Childhood Stress Impacts CVD Risk

This week’s post (which originally appeared in my weekly newsletter) includes studies that are hot off the press and cover topics including the effects of childhood adverse experiences on future cardiovascular health, the long-term effects of COVID-19 on cognitive performance, and a 4-second workout that has potent effects on fitness and anaerobic performance.

Study #1: Childhood psychosocial stress is linked with impaired vascular endothelial function, lower SIRT1, and oxidative stress in young adulthood

We often single out dietary or lifestyle factors when talking about one’s risk for developing cardiovascular disease (CVD), but mental & emotional stress may also be major factors to consider when we think about health throughout one’s lifespan. In this regard, research has shown that exposure to adverse childhood experiences — also known as ACEs (including emotional/physical/sexual abuse, violence, and neglect) — are associated with disease risk in adulthood.

This study investigated whether exposure to ACEs is associated with impaired endothelial function during adulthood. Given that endothelial dysfunction is a major step in the development of atherosclerosis and CVD, findings could potentially uncover a mechanism linking ACEs to CVD.

Two groups of women (average age ~21 years) were studied: one group who had been exposed to ACEs during childhood and another group who had no previous ACE exposure. Vascular function, levels of a gene related to longevity and CVD risk known as SIRT1, and oxidative stress were compared between groups. In addition to baseline comparisons among groups, researchers investigated whether an 8-week exercise training program would enhance vascular function in women who had experienced ACEs.

Results: Endothelial function was lower in the women with exposure to ACEs, as were levels of SIRT1 — which could mean that these low SIRT1 levels are somehow causing the endothelial dysfunction seen in this group. Levels of oxidative stress were not different between the ACE and no ACE groups.

Surprisingly, 8 weeks of aerobic and resistance exercise training did not increase vascular function in the ACE group. Overall, the results of this study point to a potential mechanism (reduced endothelial function and SIRT1 levels) by which ACEs contribute to a greater CVD risk in adulthood.

Study #2: Cognitive deficits in people who have recovered from COVID-19

There is no shortage of studies on COVID-19 and, as of recently, studies are emerging on “long COVID” — a generally uncharacterized condition in which individuals previously infected with COVID-19 experience symptoms including cardiovascular complications, brain fog, and fatigue. This is a relevant area of study, because while we know the acute impact of COVID on the lungs, the long-term implications of the disease may be even more of a burden on both individuals and the healthcare system. Whether the ravages of infection persist long after the disease has been “shed” is a relevant problem to investigate.

Results of a very large cross-sectional study (81,337 participants) provide some convincing evidence that COVID-19 may have lasting consequences for cognition and brain health, among the other maladies it inflicts upon its victims.

Results: Analyzing a dataset from participants who completed an online cognitive performance test that included items related to COVID-19 infection, authors found that compared to individuals who had never been infected with COVID-19, previously infected individuals “exhibited significant cognitive deficits.” These deficits were more pronounced among those who had been hospitalized with the disease and/or those with “biological confirmation” of infection. In fact, as the figure shows, the degree of cognitive deficit was essentially graded with the severity of disease.

There are a few limitations to a study like this — first and foremost that there are no “pre-infection” cognitive performance data; meaning we cannot compare what an individual scored on the test before infection to what they scored on the test after infection. However, given that there were seemingly no baseline differences in cognition among infected vs. never infected individuals, the data support some causal role of COVID-19 infection on cognitive performance.

We can now add cognitive and neurological effects to the somewhat established cardiovascular effects that make up “long COVID.” While we are still fighting COVID-19 and trying to prevent its spread, it seems as if we must be just as diligent in developing strategies (diet, exercise) to help infected individuals recover from and surmount the chronic effects of this respiratory disease.

Study #3: Four-Second Power Cycling Training Increases Maximal Anaerobic Power, Peak Oxygen Consumption, and Total Blood Volume

If you’re looking for the shortest workout possible (literally) that provides the most bang for your buck, then look no further.

High-intensity interval training (HIIT) has been improved upon in recent years, with many labs looking to decrease the time spent doing activity to as little as possible. This comes with a “price”, however, for to get the same benefits, one must exert exponentially more effort during these curtailed exercise bouts. A question that continues to be unresolved is: “what is the LEAST amount of exercise one can do while still receiving the MOST benefit?”

This study took that question to a new level — testing whether an extremely short “power cycling” regimen could enhance maximal aerobic capacity, blood volume, and anaerobic power.

These sessions were SHORT. For 8 weeks, participants completed 3 sessions per week. Each session involved 30 sprints that lasted 4 seconds each! Between each “all-out” effort was a rest period that began at 30s in the early weeks and then dropped to 24 and eventually 15 seconds of rest. If you do the math, that results in a total training time per session of 17 minutes at the beginning and only 10 minutes at the end of the intervention. 10 minutes per session — literally 30 minutes per week of exercise.

Results: After 8 weeks, participants had increased their VO2 peak by ~13% and their anaerobic power by around 200 Watts. Their blood volume, which is also associated with endurance adaptations and performance, also increased.

If we talk about a “minimal effective dose” for exercise — this might be close to the limit. There have been similar studies looking at 10-second “all-out” sprints, with a similar session length, but as far as the length of actual efforts is concerned, 4 is the shortest the literature has seen.

I hate to say it, but studies like this leave us with no excuse not to work out. In as little as 30 minutes per week of, admittedly, hard effort, one can improve cardiorespiratory fitness and probably several other cardiovascular and metabolic biomarkers not looked at in this study.

That’s all for this post. I hope you found at least one of these studies interesting and took away some practical, useful information. Thanks for reading.

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