Activation of back and lower limb muscles during squat exercises with different trunk flexion.
Tae-Sik Lee, Min-Young Song, Yu-Jeong Kwon
PMID 28174462WHAT IT FOUND
Bending the trunk to 30 degrees during squats did not clearly change back muscle activity, but it increased buttock and hamstring muscle activity.
Front thigh muscle activity tended to fall.
Key findings
01Erector spinae activity showed an increasing trend as trunk flexion rose from 0° to 30°, but the study did not find a clear difference.
02Gluteus maximus and biceps femoris activity significantly increased as trunk flexion angle increased, reaching 8.0 ± 4.9 %MVIC and 5.8 ± 5.2 %MVIC at 30°.
03Rectus femoris activity tended to decrease as trunk flexion angle increased, but this was not a clear difference.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
Read the rest of this summary
You get three full summaries a month, free, and we do not ask for a card. Search, the TL;DRs and your library stay unlimited either way.
What it does not show
Only 20 healthy young adults with no leg or spine injuries and a normal Q angle were studied, so this does not tell how people with knee, hip, or back problems would respond. The outcomes were muscle activation values during a single squat position, not pain, injury risk, strength gain, or function. The study did not control left-right weight distribution and did not measure abdominal muscles. Randomisation, blinding, and a primary outcome were not reported. Only a 90° knee flexion squat held for 5 seconds was tested, so other depths, loads, or tempos are unknown.
Declared interests
No funding or conflict-of-interest statement appears in the supplied text.
The easy way to misread this
Do not read increased buttock and hamstring muscle activity as proof that a bent-trunk squat is safer or better for the lower back. The study measured muscle activation only, not pain or injury, and the back muscle values showed no clear difference.