Validation of an abdominal muscle strength test with dynamometry.

Adequate abdominal strength prevents work- and sports-related injuries and stabilizes the spine for athletic activities. The double-leg-lowering maneuver (DLLM) is a popular test to assess abdominal strength because of its simplicity; however, its validity and reliability have not been studied thoroughly. To determine the validity and reliability of the DLLM, 4 examiners evaluated 28 subjects. The validity of the DLLM was evaluated with the Nicholas Hand-Held Dynamometer (NHHD) as the gold standard. The DLLM scores were compared to themselves for reliability and to NHHD scores for validity. Reliability for the DLLM was very high (r = 0.932). Validity of the DLLM was low (r = -0.338 to -0.446). The DLLM is reliable, but it has low validity to assess abdominal strength. The DLLM may be a useful tool to assess pelvic tilt motor control for spine stability, but it is not suitable for assessing muscle strength.