Brain Strength in Aging Adults
Biological process of aging includes several changes in human body which are recognized as physiological and functional impairments. Age for example brings numerous changes to the arteries such as arterial wall stiffens leading to increased blood pressure (Napoli et al. 2006). Furthermore, loss of muscle strength causes an increased risk of adverse outcomes like physical disability and inferior quality of life (Wilson et al. 2017). Additionally, a large body of data have shown that aging is associated with neurodegenerative processes in brain for example decreasing volume in hippocampus, known as memory center associated with global cognition, and leading to impaired memory and increased risk for dementia (Erickson et al. 2011).
Exercise training has shown a promising intervention to prevent or delay cognitive decline in aging adults. The hippocampus remained plastic in elderly adults (average age 68 years) after one year of moderate intensity regular weekly walking exercises compared to control group and exercise intervention was sufficient for enhancing volume of the hippocampus. Furthermore, increased hippocampal volume translated to improved memory function. (Erickson et al. 2011). According to the latest meta-analysis, exercise improved cognitive function in adults over 50 years, regardless of the cognitive status of participants. To improve cognitive function, the conclusion was to recommend both endurance and strength training of at least moderate intensity on as many days of the week as feasible, which is in line with current exercise training guidelines. (Northey et al. 2017).
"Strength training plays
a key role in improving
cognitive function in older adults"
Latest research has proven that strength training plays a key role in improving cognitive function in older adults. Significant interaction effects for strength training with executive function, memory and working memory has been documented lately (Northey et al. 2017). Earlier studies have also shown that handgrip strength is associated with cognition in a way that lower handgrip strength is related to deeper decline in cognition over time (Gallucci et al. 2013). Interestingly, Pentikäinen et al. didn’t see very clear association between handgrip strength and cognition analyzed with CERAD neuropsychology test battery, but when they performed lower body (leg extension, leg flexion and leg press) and upper body (chest press, seated row) maximal strength index with HUR strength training devices, they found that overall higher muscle strength associated clearly with better global cognition (Pentikäinen et al. 2017). The mechanism has not been extensively studied yet, but some evidence has been suggested that myokines, such as skeletal muscle derived interleukin-6 and irisin are released into the circulation during exercise, which may provide an explanation as to how regular muscle activity influences cognitive function (Pedersen et al. 2005, Zsuga et al. 2016). It could even be hypothesized the more using larger muscle groups and producing more strength, the more higher the beneficial effect to improved cognition could be?
Finally, just to put this all to practice and actual daily life, let’s think about walking ability as an example. According to study performed in the United Kingdom, 89% of ≥ 65 years old adults had walking impairment meaning that they couldn’t walk fast enough to use the pedestrian crossing speed of 1.2 m/s (Asher et al. 2012). An obvious impact of this is limited independence and reduced opportunities for physical activity and social interaction. Increasing muscle strength associated with better global cognition may be one of the major contributor to faster initiation of walking and producing the speed needed targeting to cross the street in an appropriate time and most importantly, to guarantee the independence and improved quality of life in an elderly population.
References
1. Napoli C et al. Rethinking primary prevention of atherosclerosis-related diseases. Circulation 2006.
2. Wilson D et al. Frailty and sarcopenia: The potential role of an aged immune system.
Ageing Res Rev 2017.
3. Erickson KI et al. Exercise training increases size of hippocampus and improves memory. Proc Natl Acad Sci 2011.
4. Northey JM et al. Exercise interventions for cognitive function in adults older than 50: a systematic review with meta-analysis. Br J Sports Med 2017.
5. Gallucci M et al. Body mass index, lifestyles, physical performance and cognitive decline: the "Treviso Longeva (TRELONG)" study. J Nutr Health Aging 2013.
6. Pentikäinen H et al. Muscle strength and cognition in ageing men and women: The DR’s EXTRA study. Eur Geriatr Med 2017.
7. Pedersen BK et al. Muscle-derived interleukin-6 -a possible link between skeletal muscle, adipose tissue, liver, and brain. Brain Behav Immun 2005.
8. Zsuga J et al. FNDC5/irisin, a molecular target for boosting reward-related learning and motivation. Med Hypotheses 2016.
9. Asher L et al. Most older pedestrians are unable to cross the road in time: a cross-sectional study.
Age Ageing 2012.
Arto Hautala, PhD, Adjunct Professor of Physiotherapy
HUR, Director of Research and Education
Physical Activity Guidelines Expert appointed by the Finnish Medical Society Duodecim and the Executive Board of Current Care
Chair and editor in the working group planning Finnish Current Care Guideline for exercise-based cardiac rehabilitation appointed by the Finnish Association of Physiotherapists
