Relationship between muscle-strengthening activities recommended by physical activity guidelines and knee extensor strength in the elderly.
Naofumi Yamamoto, Takenori Kawakami, Nobuko Hongu and 2 others
PMID 31320783WHAT IT FOUND
Among 223 Japanese adults aged 60 or older, strength training and heavy gardening and farming at least two days a week were linked to higher measured knee extensor strength.
Carrying heavy loads and climbing stairs or hills were not linked to higher strength.
Key findings
01After adjustment for age, sex, body mass index, overall physical activity, and other muscle-strengthening activities, sufficient reported strength training was associated with higher knee extensor strength.
02Sufficient heavy gardening and farming work was also associated with higher knee extensor strength after adjustment, but carrying heavy loads and climbing stairs or hills were not.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
The study was cross-sectional, so it cannot show that any activity caused higher strength. Participants were recruited from a health event and social activity groups, so they may not represent all older adults. Muscle-strengthening activity was self-reported with questions that did not specify intensity or duration, so people may have understood the questions differently. The authors note that recall bias and overestimation of activity frequency or duration may distort the findings for heavy load carrying and stair or hill climbing. The sample may not have been large enough to examine differences by sex.
Declared interests
The study was supported by JSPS KAKENHI grant 16K21206 to N.Y. The authors declared no conflicts of interest.
The easy way to misread this
Do not conclude that carrying heavy loads or climbing stairs and hills preserve knee extensor strength in older adults. Those activities were not linked to higher strength after adjustment, and the cross-sectional design cannot show cause.