This research study aims to investigate how experimentally induced low back pain affects electrical activity in the back and hamstring muscles. It has been long known that in fully bent-forward position, back muscles show electrical relaxation in pain-free individuals and such relaxation in absent in individuals with low back pain. To some extent, similar responses are observed in hamstring muscles as well.  Additionally it is known that pain is associated with decreased movement of the injured body part.  Previous research has not been able to answer if altered responses in the hamstring muscles are secondary to decreased movement due to pain or represent efforts of hamstring muscles (along with lumbar muscles) to stabilize spine and pelvis. Participants need to attend an half-hour screening session and a 45-minute data collection session at Unitec Mt. Albert campus.  The session involves making 4 X 4 bending forward movements during which muscle activity in lumbar and hamstring muscles will be measured.  Participants will also receive 2 small harmless injections in their back muscles to induce a short and mild bout of low back pain.  Pain should last less than 7-10 minutes.

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