Acoustic myography of the biceps and triceps brachii muscles during retrieving drills in field trial dogs.

Introduction: Field-trial dogs decelerate from speed, turn, and retrieve birds, potentially predisposing to biceps tendinopathy. Acoustic myography (AMG) measures muscle contraction. We hypothesized that braking/turning (turn) to retrieve birds produces more biceps and triceps work vs. gallop to the bird (out-run), or back with the bird (return) and that work in these muscles would be asymmetric between limbs at turn. Methods: Fourteen conditioned, orthopedically sound retrievers were fitted with wired sensors adhered bilaterally to triceps and biceps, connected to a harness holding AMG equipment. Dogs performed three 91.44 m retrieves with 2 s AMG recordings sampled mid out-run and return, and 1 s during turn; speed was calculated for each section. Data analysis: Shapiro-Wilk tests for normality and either Student's Results: Speed was faster at out-run vs. return. Biceps at out-run had greater amplitude vs. return and frequency vs. turn. Biceps at turn had greater amplitude than return. Triceps at both out-run and turn had greater amplitude vs. return. Contraction frequency was greater for biceps at out-run vs. turn and for triceps at turn vs. out-run. Discussion: Carrying a bird is not a risk factor for biceps tendinopathy in field trial dogs; excess tensile load on the biceps from triceps action at turn, and high muscle work in the biceps at out-run are likely risk factors.