Published on: May 7, 2017
by Women’s Brain Health Initiative:
Exercise is good for your entire body, including your brain. Much research has focused on the benefits of aerobic exercise for brain health, but more recently scientists have turned their attention to studying the effects of resistance training. Overall, resistance training appears to boost cognitive functioning, but its effects may vary depending on a variety of factors, including the cognitive task being tested, the exerciser’s current cognitive state, and the frequency, duration, and intensity of the exercise. While a link has been established between cognitive function and resistance training, it remains unclear whether the cognitive improvements exhibited are a direct result of the resistance exercise or whether the two may share a common alternative cause.
What is Resistance Training?
Resistance training (also known as weight training or strength training) involves moving limbs against resistance to improve muscular strength and endurance. The resistance can be provided by weights, bands, or your own body weight and gravity.
What is Aerobic Exercise?
Aerobic (or cardiovascular) exercise is any activity that stimulates an increase in heart rate and respiration, while using large muscle groups repetitively and rhythmically. Examples include walking, swimming, dancing, aerobic classes, cycling, and using cardio machines such as the treadmill and the elliptical.
Research Highlights Linking Resistance Training & Cognitive Health
A review of resistance training benefits by O’Connor et al., published in the September/October 2010 issue of the American Journal of Lifestyle Medicine, found seven randomized controlled trials that demonstrated that strength training on its own was associated with “small to moderate improvements in cognition among healthy older adults” and that memory tasks were improved the most.
A University of British Columbia-based experiment conducted by Liu-Ambrose et al. aimed to compare the effect of resistance training with “balance and tone” exercise training on the performance of executive cognitive functions in cognitively healthy women between the ages of 65 and 75.
Those who participated in resistance training classes once or twice a week over the course of twelve months experienced significantly improved executive cognitive function in the areas of selective attention and conflict resolution, compared with those who participated in the balance and tone training exercises. These results were published in the January, 2010 issue of Archives of Internal Medicine.
A later study conducted by the same research team, published in the April, 2012 issue of Archives of Internal Medicine, involved women between the ages of 70 and 80 with probable mild cognitive impairment (MCI) – a well-recognized risk factor for dementia. After only six months, the experimental group that participated in twice-weekly resistance training classes experienced significant cognitive improvement. In particular, they enjoyed “improved selective attention/conflict resolution, associative and spatial memory, and regional patterns of functional brain plasticity,” compared with twice-weekly balance and tone exercises.
Additionally, six months of twice-weekly resistance training greatly improved associative memory performance, co-occurring with positive functional changes in hemodynamic activity (the circulation of blood) in regions involved in the memorization of associations. Impaired associative memory is a hallmark of early stages of Alzheimer’s disease. Importantly, the study suggests that twice-weekly resistance training is a promising strategy to “alter the trajectory of cognitive decline in seniors with mild cognitive impairment.”
In a more recent study involving Liu-Ambrose, published in the October 2015 issue of the Journal of the American Geriatric Society, researchers focused on 54 of the women from the above-noted study who had been found during magnetic resonance imaging (MRI) scans to have white matter lesions on their brains. Cognitive impairment and falls increase morbidity and mortality in older adults, and both syndromes are associated with white matter lesions.
Thus, interventions that prevent or slow the progression of white matter lesions may help preserve cognitive function and mobility in older adults. The participants were assigned to one of three groups for a period of twelve months: (1) once-weekly progressive resistance training; (2) twice-weekly progressive resistance training; or (3) the control group, which participated in twice-weekly balance and tone training. Upon completion of the trial, the women who engaged in twice-weekly resistance training had a significantly lower volume of white matter lesions than those in the control group.
There was no significant difference between the control group and the women who participated in resistance training once per week.
“These finding suggest that weight training has the potential to moderate disease course in the brain,” explained Dr. Teresa Liu-Ambrose, co-author of the study and professor of physical therapy at the University of British Columbia. However, in order to experience the benefits of resistance training, it appears that a minimum threshold of exercise is necessary (in this case, exercising at least twice a week).
Recent research from the University of Sydney also found that resistance training improves the cognitive function of older adults with mild cognitive impairment. The Study of Mental and Resistance Training (SMART) was a randomized, controlled trial involving 100 community-dwelling adults with MCI between the ages of 55 and 86. Participants assigned to the resistance training experimental group (doing high intensity training two to three days per week) showed significant improvements in “global cognitive function” at the end of the six-month intervention, and the benefits persisted even twelve months after the supervised exercise sessions ended.
These new findings are reinforced by research from the SMART trial published in the March 2016 issue of Molecular Psychiatry by Suo et al., wherein MRI scans of participants showed an expansion of grey matter in a particular part of the brain called the posterior cingulate cortex among those who took part in the resistance training program. Reduced function in this part of the brain is an early sign of dementia. Significantly, the expansion of grey matter was associated with improvement in cognition.
What Level of Intensity is Best?
A study conducted by Cassilhas et al., published in the August 2007 issue of Medicine & Science in Sports & Exercise, assessed the impact of 24-week resistance training at two different intensities on cognitive functions in elderly, cognitively-intact men (between the ages of 65 and 75). Participants were divided into three groups: (1) resistance training at a moderate intensity; (2) resistance training at a high intensity; or (3) the control group. Researchers found that both of the exercise groups experienced more improvement in cognitive performance than the control group on several tests, supporting previous findings that resistance training helps improve cognitive functioning. Additionally, researchers found that moderate- and high-intensity resistance exercise programs had equally beneficial effects on cognitive functioning.
More recent research by Mavros et al., published in the Journal of the American Geriatrics Society in 2016, revealed that weight training should be challenging enough to maximize strength gains, because that has the largest impact on an individual’s cognitive health.
Older adults with mild cognitive impairment who participated in six months of high-intensity resistance training two or three times a week experienced significant improvements in cognitive function. These findings, which were part of the SMART trial, suggest that improvements in cognitive function are “directly related to gains in muscle strength.” Dr. Yorgi Mavros, lead author of the study and a lecturer in the Faculty of Health Sciences at the University of Sydney, explained that “the stronger people became, the more cognitive benefit. So, the key is to do resistance training frequently — at least twice a week — and at a high intensity to maximize your strengths gains, thereby maximizing benefits for your brain.”
As Dr. Liu-Ambrose has observed, resistance training tends to be an “underutilized type of exercise,” particularly among senior women, despite being incredibly beneficial. Hopefully this growing body of research encourages you to get moving and, in particular, to weight train your brain.
Source: MIND OVER MATTER
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