Does your performance in high-school gym class predict your likelihood of having pain as an adult? Perhaps not, according to a new study that examined how muscle strength in adolescence affected future musculoskeletal pain.

With one in two adults suffering from musculoskeletal disorders (MSD) like back pain and osteoarthritis in the US,  identifying risk factors of MSDs could help to decrease the prevalence of pain.

Earlier research has shown that strength training exercise can prevent pain, so Swedish researchers guessed that muscles strength in adolescence would have a protective effect on musculoskeletal pain.

They were surprised to discover that teens with low muscle strength did not have an increased risk of musculoskeletal pain later in life, even after adjusting for smoking status and physical activity. In fact, stronger teens were slightly more likely to have severe pain than their average strength peers.

The findings were based on data collected from a cohort of men aged 17-19 years who completed Sweden's mandatory conscription between 1979-2005. The young men were tested for isometric muscle strength with hand grip, elbow flexion, knee extension. Their results were then categorized into low, average, and high strength based on the 25-75th percentile.

After at an average of 17 years, the men completed the Swedish Living Conditions survey, which included questions about musculoskeletal problems, smoking status, and activity level.

Men with low muscle strength as a teenager were 7% less likely to experience musculoskeletal pain than those with average strength. The men with higher strength as a teenager had a 7% increased risk of severe pain, and a 6% increased risk of pain in the arms and legs compared to their peers of average strength.

This slightly elevated risk of severe pain could have resulted from several social and biological factors, the researchers suggested. They argued that teens with higher muscle strength may have been selected more often for higher-risk, physically-intensive jobs in the military. High workload has previously been linked to an increased risk of MSK pain.

Strength can also be affected by how the muscle fibers are distributed throughout the body. Those with higher muscle strength may have a high type II muscle fiber distribution that puts them at risk of low-back pain.

"It is important to note that our main result is not the significantly decreased risk of later musculoskeletal pain observed in men with low strength, but the non-existent risk increased in the same group," the researchers wrote. They suggested the possibility that other factors related to musculoskeletal function, like different strength measurements or flexibility, may play a bigger role in the risk of MSDs.

References

The Burden of Musculoskeletal Diseases in the United States. United States Bone and Joint Decade 2002-2011.

Timpka S, et al. Muscle strength in adolescent men and future musculoskeletal pain: a cohort study with 17 years of follow-up. BMJ Open 2013; 3(5). pii: e002656. doi: 10.1136/bmjopen-2013-002656.