Reliability of EMG time-frequency measures of XXXX during repetitive lifting.

@entity2198 @entity1295
PURPOSE: To test the short-term and long-term reliability of time-frequency electromyographic (EMG) measures of @entity1295 during repetitive dynamic lifting and compare it with the reliability of @entity2198 ( @entity2198 ) EMG measures of @entity1295 during static lifting. METHODS: Fourteen' healthy male subjects (26 +/- 5 years) repetitively (12 lifts/min) lifted and lowered a box (29 x 25 x 23 cm, 13 kg) for 4.5 min during 3 different tests on 2 different days. EMG data and the biomechanics of motion were recorded. Before and after dynamic lifting, static maximum lifting tests were performed. At the end of each of the two sessions, subjects performed a static lift at 80% of their maximum lifting force for 30 s. RESULTS: Significant @entity1295 -related changes were observed during the lifting exercise via EMG time-frequency analysis at the paravertebral L5, L2, T10, and vastus lateralis (VL) electrode sites. Two parameters for assessing @entity1295 during dynamic contractions [i.e., the Instantaneous @entity2198 (IMDF) and its time dependent change] were shown to be reproducible both in the short-term (2 h) and long-term (2 wk). The corresponding ICCs reflecting the reproducibility of values between sessions were 96.9% (L5), 98.1% (L2), 90.1% (T10), 96.4% (UT), 98.0% (GM), 89.5% (VL), and 99.0% (BF), respectively. For most EMG recording sites, the reliability of the IMDF measures was not dependent upon the postural strategy that the subject used to accomplish the lifting task or on the subject's strength as measured via the static maximum lifting test. A comparison between the ICC values of the IMDF measures and those of the parameters utilized to assess @entity1295 during static sustained lifts [i.e., the @entity2198 ( @entity2198 ) and its change during the test] revealed equally good reproducibility for most EMG recording sites. The respective ICC values that took into account time dependent trends for the IMDF parameter were 87.1% (L5), 62.4% (L2), 90.1% (T10), 0% (UT), 72.7% (GM), 45.4% (VL), and 100% (BF), and for the @entity2198 parameter 94.9% (L5), 73.0% (L2), 80.9% (T10), 100% (UT), 89% (GM), 91.7% (VL), and 90.9% (BF), respectively. CONCLUSIONS: The time-frequency approach allows one to derive EMG spectral parameters that can be used to monitor muscle @entity1295 during dynamic real-world tasks such as lifting.
