EXERCISE & BRAIN HEALTH: HOW MOVEMENT SHAPES MEMORY
- Stela Nicol
- 2 days ago
- 8 min read
Updated: 8 hours ago
There was a version of me that ran marathons.
That moved through the world with a particular kind of physical confidence, not because I was fast, or because the distances were impressive, but because my body knew what it was doing. It had a rhythm. It had stamina. It felt, in a way that is difficult to explain, like mine.
And then it stopped.
Not dramatically. Not overnight. But gradually, across months of unexplained fatigue and a heaviness that sat in my limbs like something borrowed and never returned, the running faded. A diagnosis of Hashimoto's thyroiditis explained some of it, an autoimmune condition that can gradually affect thyroid function and leave energy levels feeling very different from before.
I found other ways to move. Strength training, walking, pilates. They helped. They still help. But the running, the aerobic rhythm of it, the particular aliveness it produced, became something I thought perhaps belonged to a previous version of myself.
It is only recently, reading the research on what aerobic exercise actually does inside the brain, that I have started to think differently. Not with urgency. Not with the old pressure to perform. But with something quieter and more sustainable: curiosity and excitement.
If you have ever stopped moving for whatever reason and wondered what it means to come back, or if you are already moving and want to understand a little more deeply what that movement is actually doing, what follows might stay with you.
Because what exercise does to the brain is one of the most quietly remarkable things science has discovered. And it is far simpler to understand than most people realise.
A Small Structure With a Big Role
Deep inside the brain sits a small structure, one on each side, curved a little like a seahorse. This is the hippocampus and it plays a central role in how we form new memories and make sense of our experiences over time.
It is particularly involved in the kind of memory we use every day: remembering where you left things, following the thread of a conversation, recognising that this week feels different from last week, that this person said something different from what you remember. It is not the only part of the brain involved in memory, memory is distributed across networks throughout the brain, but it is one of the most important players, and one of the most sensitive to how we live.
What many people don't know is that the hippocampus tends to become gradually smaller with age, even in otherwise healthy adults. This is one of several changes that can influence memory over time, although the relationship is not always straightforward and varies considerably from person to person.
The occasional forgotten name or misplaced set of keys is a familiar part of being human. But researchers have become increasingly interested in understanding what helps the brain remain resilient across the years.
This is where exercise and brain health become the same conversation.
What Exercise Actually Does to Your Brain
One of the things I found unexpectedly comforting when I started reading this research was that the brain does not seem particularly interested in whether movement looks impressive.
It responds to consistency.
When we move our bodies regularly, especially in ways that gently raise the heart rate, a remarkable series of changes begins to unfold inside the brain. Blood flow increases. Chemical messengers associated with learning and adaptation become more active. Research suggests that exercise helps create the conditions that support the growth and survival of new neurons within the hippocampus, the region so closely involved in memory.
The brain, it turns out, is far more adaptable than many of us were taught to believe.
A landmark study followed 120 older adults for one year. Half spent time walking at a moderate pace three times each week. The other half participated in stretching and toning activities.
By the end of the study, brain scans showed that the walking group had experienced a small but measurable increase in hippocampal volume around 2% on average. The researchers noted that this effectively offset roughly one to two years of the age-related shrinkage typically seen in that part of the brain. (Link)
What strikes me most is not the number itself, but what produced it.
Not an extreme training programme.
Not marathon preparation.
Not extraordinary effort.
Walking. Three times a week. Over time.
The memory benefits followed the physical changes. Participants showed improvements in the kinds of cognitive abilities that shape everyday life: remembering where things are, holding information in mind, navigating familiar environments, keeping track of the details that allow one day to feel distinct from the next.
There is something hopeful in that. The brain remains responsive to how we live, and movement appears to be one of the ways we stay in conversation with it.
Earlier Than Most of Us Think
When many of us hear conversations about memory, we imagine they belong to some distant future version of ourselves.
Retirement.
Older age.
A concern for later.
But the brain does not divide life into such neat categories.
Researchers have found that some of the gradual changes associated with aging begin earlier than many people expect. Not because something is wrong, but because aging itself is an ongoing process rather than a sudden event.
Which means that exercise and brain health are not a conversation reserved for sixty-five. They are a conversation to have now, in whatever decade of life you happen to be living.
A growing body of research suggests that regular aerobic movement (the kind that gets the heart working) supports memory, executive function, attention, and cognitive resilience across the lifespan. More importantly, it suggests that the brain responds more to repeated movement woven into ordinary life than to occasional bursts of effort. (Link)
You do not need to run fast, or push hard, or achieve anything particular. You need to show up, regularly, to movement that raises your heart rate even modestly.
That reframe matters.
Especially for anyone who stopped moving because the full version felt impossible and assumed that a smaller version was not worth doing.
It is worth doing.
Not because every walk transforms the brain overnight, but because small actions repeated over time appear to matter far more than we often realise.
Aerobic, Strength, Walking.
What the Research Actually Says.
One of the things I found reassuring was learning that the brain does not seem especially concerned with whether movement looks impressive from the outside.
It simply responds to being used.
Aerobic exercise e.g. running, cycling, swimming, brisk walking, dancing, currently has the strongest evidence for supporting hippocampal health and memory over time. This is the kind of movement that asks the heart and lungs to participate a little more fully.
Strength training matters too.
Not because it replaces aerobic exercise, but because it contributes something different. Research suggests it supports mood, metabolic health, functional independence, and aspects of cognitive wellbeing through pathways that are not identical to those of aerobic exercise.
The picture that emerges is not one of competition between different forms of movement. It is one of complementarity.
And then there is walking.
Walking is often treated as the modest cousin of more ambitious forms of exercise, yet the evidence tells a different story. Studies have found that people who walk regularly tend to show better markers of brain health over time, including larger hippocampal volumes in later life. (Link)
Walking is not what happens when "real exercise" is unavailable.
It is exercise.
Simple. Accessible. Underestimated.
For many people, it may be one of the most sustainable forms of exercise and brain health support available.
The Grief of Stopping.
And What Returning Can Look Like.
I want to name something the research rarely addresses directly, but that some women will recognise: the particular grief of losing a movement practice that once felt like part of who you were.
When you stop running or stop moving in the way your body once moved freely, it is not only a physical loss.
It can feel like an identity loss.
A rhythm you relied on.
A way of processing the world.
A place where you felt most clearly yourself.
And when the stopping is not entirely your choice but a response to a body that has changed without your permission through illness, hormonal shifts, exhaustion, injury, caregiving responsibilities, or something harder to name, there is often another layer of sadness beneath it.
What I want to offer here, gently, is that returning does not have to look like reclaiming.
It does not have to look like becoming the person you once were.
It can look like discovering what movement means to this version of your body, in this season of your life, with what you now understand about what it offers your mind as well as your muscles.
For those of us navigating thyroid conditions, autoimmune challenges, chronic fatigue, or periods of depleted energy, high-intensity exercise is not always the answer. Sometimes it may even work against what the body needs in that moment.
This is always worth exploring with a healthcare professional who understands your individual situation.
But gentle, consistent movement remains meaningful.
The brain benefits of exercise do not appear to require perfection.
They require participation.
What Consistency Actually Means in Real Life
The research is remarkably consistent on one point above all: the brain seems to benefit most from movement that returns again and again over time.
Not a heroic week.
Not a sudden burst of motivation.
Not a single transformative workout.
A practice.
Animal studies suggest that when exercise stops, some of the biological changes associated with it gradually fade. Human research cannot tell exactly the same story in exactly the same way, but it points in a similar direction: the benefits of movement are supported by continuity.
This is clarifying rather than discouraging.
It means the goal is not to have exercised.
It is to keep finding ways to move.
A walk after dinner.
A swim on a Saturday morning.
A pilates class you enjoy enough to attend next week as well.
The details matter less than we sometimes think. What matters most is finding something you can return to with reasonable consistency.
A Quiet Invitation Back
Perhaps that is the part of this research that stays with me most.
Not that movement can change the brain, though that is remarkable in itself. But that the brain continues responding long after many of us assume the opportunity has passed.
If you have spent time away from movement, because of illness, exhaustion, caregiving, work, grief, or simply life unfolding as it does, there is something reassuring in knowing that the body does not require a dramatic comeback story.
The brain is not measuring what you used to do. It is responding to what you do now.
The research suggests that the brain retains an extraordinary capacity to adapt throughout life. Not perfectly. Not endlessly. But far more than we once believed.
For me, that has changed the way I think about returning. Not as an attempt to become the person who ran marathons. But as a way of caring for the person who is here now. And I think that is enough reason to begin again. :-)
What would it feel like to move your body this week, not to achieve anything, but simply to care for the mind living inside it?
Wellness "Wisdom", Continued ...
The information provided in this post is for educational and informational purposes only. It is not intended as medical advice or a substitute for professional consultation. Please consult a healthcare provider before making any significant changes to your diet, exercise, or wellness routine to ensure they align with your individual needs and circumstances.
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