We need high intensity exercise to maximize brain health… "Not only for exercise interventions to enhance neuroplasticity but “to maximize the therapeutic potential of non-invasive brain stimulation.”
A single bout of cardiovascular exercise can enhance plasticity in human cortex; however, the intensity required for optimal enhancement is debated. We investigated the effect of exercise intensity on motor cortex synaptic plasticity, using transcranial magnetic stimulation. Twenty healthy adults (M age = 35.10 ± 13.25 years) completed three sessions. Measures of cortico-motor excitability (CME) and inhibition were obtained before and after a 20-min bout of either high-intensity interval exercise, moderate-intensity continuous exercise, or rest, and again after intermittent theta burst stimulation (iTBS). Results showed that high-intensity interval exercise enhanced iTBS plasticity more than rest, evidenced by increased CME and intracortical facilitation, and reduced intracortical inhibition. In comparison, the effect of moderate-intensity exercise was intermediate between high-intensity exercise and rest. Importantly, analysis of each participant’s plasticity response profile indicated that high-intensity exercise increased the likelihood of a facilitatory response to iTBS. We also established that the brain-derived neurotrophic factor Val66Met polymorphism attenuated plasticity responses following high-intensity exercise. These findings suggest that high-intensity interval exercise should be considered not only when planning exercise interventions designed to enhance neuroplasticity, but also to maximize the therapeutic potential of non-invasive brain stimulation. Additionally, genetic profiling may enhance efficacy of exercise interventions for brain health.
My personal experience aligns with these findings. An interesting problem emerged in my 70’s and in close friends of a similar age. Whereas cardiopulmonary capacity can be a limiting factor in HIIT activities when younger, at some point, muscle innervation becomes the limiting factor as the muscle nerve/muscle cell ratio continues to decline.
I experience this situation when climbing very steep hills even on a relatively smooth path (eliminating balance and other factors). I have difficulty climbing fast enough to get out of breath and reach and sustain Zone 5. I can sense that muscle innervation is the limiting factor.
Ironically, one of the best ways to slow or even partially reverse that declining ratio is HIIT.
Now, a year later and (ahem) a year older, I can still attest to the applicability of what @RapAdmin reported above. All forms and intensities of exercise benefit me but short high intensity bursts have special effects that I don’t have good metrics for other than to note my subjective sense of well being, better balance (a small but real issue as I get older), and more energy. I get some HIIT working in our yard. Moving plants around, repairing drip lines, pruning, etc. is generally low intensity Zone 1 work but digging holes with my 7-foot 35 pound steel bar in our extremely rocky soil (eastern edge of greater Phoenix area) is excellent HIIT. The professionals in this area use electric jackhammers in this particular area. It can take 20 minutes or longer to dig a single hole which I break up into a half dozen or more HIIT bursts with the steel bar, each burst sending my HR well into Zone 5 and soon leaving me out of breath. Overall, I try to get some HIIT at home, some in bursts on hills, and occasionally on a stairstep machine or treadmill, which I find mostly unsatisfactory.
I can identify with your observation on common tasks. I was introduced to the bar you mentioned when I was 13 and helped out my uncle and father in a landscape business they had. I have had one in my shed for many decades and it still gives me a workout in the yard occasionally. It is called a San Angelo bar (not many people know that). A very useful tool.
I have been trying high-intensity interval training for the past 2 weeks for about 10 to 15 minutes each day (4x4 – warm-up phase of a few minutes + 4 sessions for about 40 seconds at about 90% to 95% maximum heart-rate as measured by 220-age, interleaved with 4 sessions for recovery + a few more seconds delay in getting treadmill up to speed each session), and can definitely feel a lasting effect hours after completing it. The most obvious seems to be taut muscles in my abdominal area (e.g. obliques) and legs. Walking also seems to be easier even a few hours after – muscles seem stronger, seemingly requiring less effort to walk.
Supposedly (according to a Google search), HIIT can boost nitric oxide levels in the body long after each session, and regular HIIT can raise one’s baseline level of nitric oxide production. It also raises growth hormone levels up to an hour or two after finishing, and may also raise baseline levels.
All-out sprints have at least two advantages over a slow, lazy jog. One is that they generate endorphins, which creates euphoria. The faster you go, the more euphoric you feel. The second is that intervals provide a full-body fortification that protects against future illness. For example, I once had a case of septic shock that sent me to the hospital. While sepsis has a mortality rate of about 60% for those in their 70s, I was out of the hospital in five days. I attribute my rapid recovery–indeed, that I recovered at all–to a lifelong habit of high-intensity exercise.
I find cardio to be the limiting factor and weaker cardio makes it hard to reach muscular failure. Now that I’m training cardio consistently I’m finding myself reaching closer to muscular failure in more exercises, it is great.
I’m curious to see if there are things other than exercise that can increase the concentration of oxygenation haemoglobin in the prefrontal cortex:
“The high concentration of oxygenated haemoglobin (O2Hb) in the prefrontal cortex (PFC) during exercise improves cognitive performance. In this study, we aimed to elucidate the relationship of cognitive function with the O2Hb concentration difference between the left and right PFC (L-PFC and R-PFC, respectively) during sustained exercise. We enrolled 12 healthy adult males who, after a 4-min rest and warm-up, performed a 40-min exercise regime at a workload corresponding to 50% maximal oxygen consumption. A 2-back task was performed, and the reaction times (RTs) were recorded before exercise, immediately after exercise, and 20 min after exercise. Near-infrared spectroscopy was used to monitor L-PFC and R-PFC. RT was shortened immediately and 20 min after exercise, and O2Hb concentration difference between L-PFC and R-PFC positively correlated with RT 20 min after exercise. These findings suggest that 40-min exercise induced a phenomenon of neural compensation.”
Finger tapping and verbal fluency tasks:
“This study aimed to examine the extent to which age and MCI affect cerebral blood flow, which was measured using NIR spectroscopy during category, finger-tapping, and dual tasks. Additionally, the effectiveness of cerebral oxyhemoglobin signal measurements in categorizing elderly participants with and without MCI was examined. Our results show that the oxyhemoglobin levels during these tasks were not able to distinguish between elderly participants with and without MCI. However, in participants both with and without MCI, the results suggest that finger-tapping, as well as verbal fluency tasks, can also be effective in activating the prefrontal cortex.”
Mouth breathing increased oxygen load in prefrontal cortex:
“The hypothesis that mouth and nasal breathing give rise to different cerebral hemodynamic responses in the prefrontal cortex was corroborated in this study. We found that mouth breathing caused an increased oxygen load in the prefrontal cortex. This is the first study to compare the effect of breathing routes on hemodynamic responses in healthy individuals during the waking hours. It is possible that a few minutes’ detection of phase responses using vector-based NIRS could become an effective way to quantitatively diagnose differences in breathing routes on the basis of this increased oxygen load.”
