Sarcopenia, or age-related muscle loss, is a major cause of disability and loss of independence in the elderly. While muscle mass and strength begin to decline around the age of 30, this loss can be especially debilitating as one reaches elderly age. Bone fractures and decreased physical activity are two of the more common consequences related to sarcopenia, and usually contribute to significant decline in the elderly population.
Approximately 18 million individuals living in the U.S. were affected by sarcopenia in 2010, and this number is expected to rise as the Baby Boomer generation nears retirement age. Additionally, the health care costs related to complications of sarcopenia can amount to tens of billions of dollars annually.
Though loss of muscle mass is inevitable as an individual ages, there are some preventative measures that can be taken to slow this decline. Physical activity and sufficient protein intake are both very important for elderly individuals trying to prevent excess loss of muscle mass and strength. Additionally, research supports that vitamin D status is an important component of the musculoskeletal system. Therefore, researchers from this study examined the association between 25(OH)D, physical activity (PA), knee pain and muscle quality in community-dwelling older adults.
Over 10 years, researchers studied 1,099 elderly individuals, over the age of 50 residing in Tasmania, a small-island state off the coast of Australia. Initial assessment for all participants were held between March 2002 and September 2004. Follow up appointments occurred at two and a half, five and 10 years after the initial assessment. The researchers evaluated the following variables during the initial and follow up interviews:
- Anthropometrics and biometric values, including weight, height, bone density and vitamin D status.
- Lower limb muscle strength and quality which were measured using dynamometers.
- Physical activity status was measured by each participant’s self-reported data.
- Knee pain, stiffness and physical limitations which were measured by the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), with higher scores indicating decreased functionality and increased pain.
This is what the researchers found:
- Approximately 54% of the participants joined the 10-year follow up appointment.
- Over the 10 year period, the highest vitamin D levels were associated with increased lower limb lean muscle mass (LLM) (95% CI: 0.001-0.01), lower limb muscle strength (LMS) (95% CI: 0.05-0.27) and lower limb muscle quality (LMQ) (95% CI: 0.01-0.02).
- When analyzing the individual changes of each participant over 10 years, these associations remained significant, with the exception of LLM.
- Higher WOMAC scores were associated with decreased LMS and LMQ, but not LLM (95% CI: -0.28-(-0.13) and -0.02-(-0.01), respectively).
The researchers concluded:
“Our findings demonstrate that both between-person and within-person and fluctuations in 25(OH)D, pain, dysfunction and physical activity were associated with muscle changes.”
This study was strengthened by the analysis methods which allowed the researchers to measure and compare data between all the participants, and measure changes in each individual over time. However, there were some limitations of this study to note. Due to the long follow up time, nearly half of the participants dropped out of the study. Usually, this data is thrown out of the results and included in participant exclusion criteria. In this circumstance, the researchers estimated the outcomes of lost-to-follow-up participants, instead of throwing out this data.
The Vitamin D Council recommends supplementing with between 5,000 IU and 10,000 IU per day in order to maintain optimal vitamin D status (40-80 ng/ml). Testing your vitamin D levels every six months is important for ensuring that the dose you are taking is right for you. For all questions regarding vitamin D supplementation and testing, please email [email protected].
Peterson, R. Vitamin D levels are associated with muscle strength and quality in an older population. The Vitamin D Council Blog & Newsletter, 10/17.
Balogun, S. Longitudinal Associations of Serum 25-hydroxyvitamin-D, Physical Activity, and Knee Pain and Dysfunction with Muscle Loss in Community-dwelling Older Adults. The Gerontological Society of America, 2017.