Posts tagged older adults
Muscle Loss and Aging
aging-atrophy-muscle mass-exercise

All of us will undergo a progressive loss of muscle mass as we age called sacropenia.  The key modifying variable is how quickly an individual loses this muscle mass over time.  Previous research on resistance training has shown a significant reduction in the rate of this loss over time among both experienced and novice weight lifters.  A new study examined which muscles are most susceptible to muscle mass loss with aging allowing for better exercise prescription and prevention.

Ikezoe and colleagues compared the cross sectional area of lower body muscles between 20 year old and 83 year old subjects (Arch Gerontology and Geriatrics. 2011).  The authors then compared the muscle size differences between old and young participants to determine which muscles atrophied the most with the aging process.  The smallest differences in muscle mass were noted in the thigh muscles including the quadricep and hamstring while the greatest differences were noted in the hips.  On average these hip muscles were only 1/2 the size of their younger counterparts.  This study highlights the importance of resistance training among all age groups, especially in the hip musculature.   To learn more about the benefits of resistance training contact your local Physical Therapist.

ACL Reconstruction in Older Athletes

ACL injuries are on the rise across the United States as more individuals participate in athletic activities.  As described in prior posts, the majority of these ligament injuries do not involve contact but rather occur with deceleration and directional changes in sports.   Athletes with decreased strength, balance, and coordination are unable to dissipate forces placing greater loads on their knee ligaments.  One segment of the population at risk of ligamentous injury due to these factors includes “weekend warrior” athletes over the age of 40. 

The necessity of repairing a torn ACL injury in these older athletes is debatable with many patients able to return to activity, albeit often at a lower level, with conservative treatments alone.  A recent review article examined the outcomes associated with ACL repair among athletes >40 years old.  Mall and colleagues analyzed the results of 452 patients (average age 48) who underwent ACL repair (Sports Health. 2016).  The authors reported few complications and a low failure rate among this population along with A or B outcomes in >80% of patients. 

The results of this review suggest ACL repair combined with post operative Physical Therapy is a safe and effective alternative for patients with ACL tears. 


Age and Running Biomechanics

Last year an estimated 30 million people ran at least 50 days for exercise and health benefits (Running USA).    The fastest growing segment of the running community includes older adults who gain impressive cardiovascular, muscle, bone, and mental health benefits compared to their sedentary peers.   In addition, contrary to popular but incorrect old wives tales about running and arthritis these active older adults experience less pain than their sedentary peers (Bruce et al. 2005).  Our previous posts on the older adult running community detailed specific cardiovascular and gait changes which take place due to aging.   These losses in flexibility, strength and balance increase the already high rates of overuse injuries among runners.  A better understanding of running gait changes through the life cycle may help us prevent future injuries among this population of runners. 

A recent study in the Journal Medicine and Science in Sports and Exercise studied the running gaits of 110 experienced runners between the ages of 18-60  (DeVita et al. 2016).  Consistent with the previous literature the authors noted each age group older than 18 demonstrated a progressive loss of running velocity.  These changes were largely due to decreased stride length vs. stride frequency compared to the younger participants.  Further, older runners ran with decreased ankle power which translated into decreased horizontal and vertical forces at push off.  The presence of ankle changes with age, but the absence of hip or knee changes, indicates the importance of the ankle for both energy absorption and propulsion during running.      

The Impact of Aging on the Running Gait Cycle

Runners older than 50 years old have shown the greatest increase in participation rates among long distance runners.  In a previous post we described the impact of aging on running speed.   In each decade after age 40 a runner will lose approximately 10% of their VO2 max due to changes in their musculoskeletal and cardiovascular systems.  Thus a runner wishing to hold a 7 minute per mile pace into their later decades of life would need to run at a higher intensity to maintain the same speed.  Our prior post detailed research showing older runners demonstrated decreased step length, but no change in step frequency, compared to their younger peers likely explaining part of this change in speed.  

In addition to participating at higher rates, older runners also sustain a greater number of injuries compared to their younger counterparts (McKean et al. 2006).  Authors believe the greater impact forces and loading rates at foot contact, as well as, reduced decelerating motion in lower extremity joints may explain some of the increase in injury rates among this age group (Fukuchi et al. 2008).  These loading biomechanics are associated with stress fractures, heel pain, and shin splints. Until recently, it was not known if male and female older runners differed on their running mechanics.  

A recent article in the International Journal of Sports Physical Therapy confirmed prior findings of younger vs. older runners (Kline et al. 2015).  The authors studied 41 subjects divided into four groups based on age and sex and data was collected during their running gait.  The researchers found higher forces and loading rates in older vs. younger runners but little difference between male and females.  

Older runners should work to maintain flexibility and strength in their hips, knees, and ankles to allow these joints to dissipate forces associated with the gait cycle.  In addition, older athletes are encouraged to work with a local Physical Therapist on their running gait to reduce the risk of lower extremity injury and time off running.    

Aging, The Older Athlete, and Running Speed

Running is one of the most common forms of exercise due to its' wide appeal, minimal equipment needs, and aerobic benefits.  Around Boulder it is not uncommon to see runners of all ability levels and ages enjoying many of the great outdoor running paths and trails.  Prior research has shown older runners run at slower speeds than younger adults due to cardiovascular and musculoskeletal changes due to aging.  Exercise physiology research shows a 10% decline in cardiovascular capacity with each decade after age 40.  Thus a runner holding the same minute/mile pace would be running at a higher % of their VO2 max with each decade after 40.  

aerobic capacity over lifespan, runners

An interesting article by DeVita and colleagues examined the impact of aging on running biomechanics (Med Sci Sports Exerc 2015).  The authors examined 110 health runners within a biomechanics laboratory to determine running speed, running forces, and biomechanics.  The results showed running speed decreased in older runners secondary to a decrease in stride length but no change in stride rate (Running Speed = stride length x stride frequency).  This loss of stride length was accompanied by a stride height and push off due to decreased activation of the ankle musculature.  Interestingly, no change was noted in the hip and knee activation in these runners.  The loss of ankle strength may place these athletes at greater risk of ankle and foot injuries during run training.  It is not known if ankle strengthening could improve mechanics in these runners.