Rhomboid muscle electromyography activity during 3 different manual muscle tests

Smith J, Padgett DJ, Kaufman KR, Harrington SP, An K-N, Irby SE. Rhomboid muscle electromyography activity during 3 different manual muscle tests. Arch Phys Med Rehabil 2004;85:987-92. Objective To determine which of 3 previously published rhomboid manual muscle tests (MMTs) elicits the maximal rhomboid electromyographic activity in an asymptomatic population. Design Criterion standard. Setting Motion analysis laboratory at tertiary care medical center. Participants Eleven male volunteers (age range, 24-40y) without shoulder or neck pain. Interventions Not applicable. Main outcome measures Peak 1-second normalized electromyographic activity in the rhomboid muscle during 8 different MMT positions, including 3 different rhomboid MMT positions (Kendall, Kendall-Alternative, Hislop-Montgomery). Results The Kendall MMT (78% maximal voluntary contraction [MVC]) produced higher rhomboid electromyographic activity than the Kendall-Alternative (71% MVC) or the Hislop-Montgomery MMT (52% MVC), but the differences were not statistically significant. The posterior deltoid MMT generated the greatest rhomboid electromyographic activity of all MMTs, and 4% to 30% greater rhomboid electromyographic activity than the 3 rhomboid MMTs (P=.0001; posterior deltoid > Hislop-Montgomery). Electromyographic profiles of the Kendall and Kendall-Alternative MMTs were similar, whereas the Hislop-Montgomery MMT produced less upper trapezius activity (P=.0001 vs Kendall and Kendall-Alternative) and more latissimus dorsi activity (P=.0001 vs Kendall-Alternative). The standard MMT positions for the middle trapezius, levator scapula, posterior deltoid, and latissimus dorsi produced the maximal electromyographic activity for their respective target muscles. Conclusions The posterior deltoid MMT position should be used to produce maximal rhomboid electromyographic activity for normalization purposes during kinesiologic studies. The Kendall and Kendall-Alternative rhomboid MMT are likely to be clinically indistinct. It is unlikely that clinicians can use standard MMT positions to distinguish rhomboid strength from synergists, such as the levator scapula and middle trapezius muscle, for diagnostic purposes.