The Surprising Reason Why Older Adults Move Slower (According to Science)
Science reveals a surprising reason why older adults move slower! It's not just muscle loss. This blog post explores the latest research and offers tips to stay active as you age.
DR T S DIDWAL MD
6/6/20247 min read
A new study published in the Journal of Neuroscience. suggests older adults move slower because it takes more energy than younger adults. Researchers believe this inefficiency stems from cellular and strategic levels, affecting how muscles convert energy and how the brain plans movements. The study also explores the reward system's role in the movement, finding that while both age groups respond to rewards, older adults prioritize effort conservation. These findings could lead to new diagnostic tools for movement disorders and a deeper understanding of how we move as we age.
Key points
A New Explanation for Slower Movement in Older Adults: Traditionally, slower movement in older adults was attributed to factors like muscle loss and decreased activity. This study suggests an additional reason: it may cost older adults more energy to move compared to younger adults.
Energy Inefficiency: The study found that muscle cells in older adults may be less efficient at converting energy into movement. Additionally, older adults may use less efficient movement strategies, recruiting more muscles to compensate for decreased strength, which requires more energy.
Reward Circuitry and Movement: The study investigated the brain's "reward circuitry" and its role in movement. While both younger and older adults moved faster for a reward, they achieved this speed increase differently. Younger adults moved their arms faster, while older adults had quicker reaction times.
Preserved Reward Circuitry But Heightened Effort Sensitivity: The study suggests that the reward circuitry may be somewhat preserved in older adults. However, they are more sensitive to the effort required for movement compared to younger adults, indicating that age may have a stronger impact on effort sensitivity than reward sensitivity.
Potential Applications for Diagnosing Neurological Disorders: Researchers believe these findings could lead to new diagnostic tools for movement disorders like Parkinson's disease. A deeper understanding of slowed movement in various disorders could provide insights into their underlying causes and potentially lead to better treatments.
The Economics of Movement: The study suggests that the brain prioritizes movement based on a cost-benefit analysis. Older adults may move slower to conserve energy and reduce the risk of injury.
Practical Tips for Maintaining Mobility: The article offers tips for older adults to maintain mobility, such as regular exercise (including strength training, flexibility exercises, and balance training), a healthy diet, and mental activities. It emphasizes listening to your body and seeking professional advice to develop a personalized exercise plan.
Why We Slow Down As We Age: It's Not Just About Muscle Mass
It's a common observation that people tend to move slower as they get older. Traditionally, science has attributed this to a number of factors, including a slower metabolism, loss of muscle mass, and decreased activity levels. However, new research suggests there may be more to the story. A recent study conducted by scientists at the University of Colorado Boulder found that older adults may move slower because it costs them more energy than younger adults. This finding could have significant implications for the development of new diagnostic tools for neurological conditions.
The Study: How Movement Patterns Were Analyzed
The study involved 84 healthy participants, divided into two groups: younger adults between the ages of 18 and 35, and older adults between the ages of 66 and 87. Participants were asked to reach for a target on a screen while holding a robotic arm in their right hand. The robotic arm mimicked the movements of a computer mouse. By analyzing the patterns of the participants' movements, the researchers observed that older adults modified their movements in ways that seemed to conserve energy compared to younger adults.
Energy Inefficiency and Movement Strategies
"With age, our muscle cells may become less efficient in transforming energy into muscle force and ultimately movement We also become less efficient in our movement strategies, possibly to compensate for lower strength. So we recruit more muscles, which costs more energy, to perform the same tasks."The study suggests that the body's natural decline in efficiency as we age may be a contributing factor to slower movement in older adults. This inefficiency can occur at the cellular level, where muscles become less adept at converting energy into movement, and at the strategic level, where the brain recruits more muscles to compensate for decreased strength, even for simple tasks.
The Reward Circuit and Its Role in Movement
The study also investigated how aging might affect the brain's "reward circuitry," which is influenced by dopamine production. Dopamine is a neurotransmitter that plays a role in motivation, reward-seeking behaviour, and movement. The body's production of dopamine naturally declines as we age. In another part of the study, participants were asked to use the robotic arm to reach targets on a screen, while a "bing" sound would reward successful reaches. The researchers found that both younger and older adults moved faster when they knew they would receive the rewarding sound.
However, there were interesting differences in how the two age groups achieved this speed increase. Younger adults simply moved their arms faster, while older adults improved their reaction times, initiating their movements with the robotic arm about 17 milliseconds sooner on average.
Preserved Reward Circuitry but Heightened Sensitivity to Effort
The current study's findings indicate that while older adults may still be motivated by reward to some degree, they are much more sensitive to the effort required for movement compared to younger adults. This suggests that age may have a stronger impact on sensitivity to effort than sensitivity to reward.
Potential Applications for Diagnosing Neurological Disorders
The researchers believe their findings may contribute to the development of new diagnostic tools for movement-related disorders such as Parkinson's disease and multiple sclerosis. Why do disorders such as depression, which are associated with reward circuitry in the brain, also lead to a general slowing of movement? A deeper understanding of the reasons behind slowed movement in various disorders could provide valuable information about their underlying causes, potentially leading to the identification of more effective interventions. The ease of measuring movement makes it an attractive potential biomarker for neurological health. Tracking a person's movements in a clinical setting or even during daily activities could one day provide valuable insights into their neurological health.
Encouraging Exercise for Brain and Body Health
While more research is needed to fully understand the connection between aging, movement, and the brain, several experts commented on the importance of exercise for overall health as we age. Even though physical activity may require more effort for older adults, it remains crucial for maintaining muscle mass, joint flexibility, and overall well-being.
Regular exercise has been shown to improve cardiovascular health, enhance mood, and boost cognitive function. For older adults, engaging in activities like walking, swimming, and strength training can help mitigate some of the physical declines associated with aging. Exercise not only strengthens muscles but also stimulates the production of neurotrophic factors, which support brain health.
The Economics of Movement: An Adaptive Strategy
The concept of movement as an economic decision is intriguing. The brain, acting as a rational agent, evaluates the costs and benefits of movement. For older adults, the increased metabolic cost of movement due to less efficient muscle function and higher overall effort leads to a strategic adjustment in movement patterns.
This adaptive strategy can be seen as the body's way of conserving energy and reducing the risk of injury. By moving slower, older adults can minimize the strain on their muscles and joints, which may help them maintain mobility and independence for longer.
The Broader Implications of the Study
The findings of this study have broader implications beyond understanding age-related slowing of movement. They offer insights into how the brain prioritizes and values different actions based on the effort required and the potential rewards.
In clinical settings, these insights could be used to develop more targeted interventions for individuals with movement disorders. For example, therapies that focus on reducing the perceived effort of movement or enhancing the reward value of physical activity could be beneficial.
Moreover, the study underscores the importance of considering both physical and neurological factors in the treatment of age-related conditions. By addressing the metabolic costs of movement and the brain's valuation of effort, healthcare providers can develop more comprehensive strategies to support healthy aging.
Practical Tips for Maintaining Mobility as We Age
Based on the findings of the study and current understanding of aging and movement, here are some practical tips for older adults to maintain mobility and reduce the impact of increased effort costs:
Regular Exercise: Engage in a balanced exercise routine that includes aerobic activities, strength training, flexibility exercises, and balance training. Aim for at least 150 minutes of moderate-intensity aerobic activity per week.
Stay Active Throughout the Day: Incorporate physical activity into daily routines, such as walking, gardening, or taking the stairs. Frequent, short bursts of activity can be beneficial.
Strength Training: Focus on exercises that build muscle strength, such as weight lifting, resistance band exercises, or bodyweight exercises. Stronger muscles can help reduce the metabolic cost of movement.
Flexibility and Balance Training: Activities like yoga, tai chi, and stretching exercises can improve flexibility and balance, reducing the risk of falls and enhancing overall movement efficiency.
Healthy Diet: Maintain a balanced diet rich in nutrients that support muscle health, such as protein, vitamin D, and calcium. Adequate hydration is also important for muscle function.
Mental Health: Stay mentally active and engaged. Activities that stimulate the brain, such as puzzles, reading, and social interactions, can support cognitive function and overall well-being.
Listen to Your Body: Pay attention to signs of fatigue or discomfort and adjust activities accordingly. It's important to find a balance between staying active and allowing the body to rest and recover.
Seek Professional Advice: Consult with healthcare providers or physical therapists to develop a personalized exercise plan that addresses individual needs and limitations.
Conclusion
The study by the University of Colorado Boulder provides valuable insights into why we move slower as we age. The increased metabolic cost of movement and the brain's adaptive strategies to conserve energy play significant roles in this process. Understanding these factors can inform the development of new diagnostic tools and interventions for age-related movement disorders.
By promoting regular physical activity, addressing both physical and neurological factors, and exploring new research directions, we can better support healthy aging and improve the quality of life for older adults
Journal Reference
Summerside, E. M., Courter, R. J., Shadmehr, R., & Ahmed, A. A. (2024, February 26). Slowing of Movements in Healthy Aging as a Rational Economic Response to an Elevated Effort Landscape. Journal of Neuroscience. https://doi.org/10.1523/jneurosci.1596-23.2024
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