Trunk Flexor Endurance And Low Back Pain In Men And Women
The link between fatigue properties of the trunk flexors and low back pain (LBP) was compared between 18
participants with a history of LBP and 18 healthy controls. Participants were asked to maintain the trunk in a horizontal
position as long as possible against a load equal to 20, 40, or 60% of their maximal voluntary isometric contraction (MVIC
v) strength of the trunk flexors. Time to task failure (TTF) and changes in median power frequency (MPF) of the trunk
flexors during the fatigue protocol were the primary dependent measures. As expected, TTF decreased as task difficulty was
increased (F=76.5, p<0.05). On average, TTF was 59.82 (±21.2 min) minutes for 20% MVIC, 28.61 (± 19.1 min) minutes at
40% MVIC, and 9.39 (±10.4 min) minutes for 60% MVIC. However, there was no main effect of group on time to task
failure. Normalized slopes of MPF revealed group differences for the left and right rectus abdominus, but only at the 40%
MVIC load condition (p<0.05). This study confirms others demonstrating that participants with a history of LBP do not have
a significant loss in abdominal endurance versus healthy controls, raising questions regarding the role of the trunk flexor
muscles in low back pain.
Keywords- Muscle Fatigue, Low Back Pain.