Incline and decline treadmill trotting produce electromyographic changes in specific canine shoulder muscle activity:...

To identify the effects of incline and decline treadmill trotting on forelimb muscle activity in dogs using electromyography (EMG).

Data were collected for a prospective within-subject, repeated-measures study in January and February of 2025 where subjects were trotted on a level treadmill, 5% incline, 10% incline, 5% decline, and 10% decline. Surface EMG data were collected bilaterally from the scapular portion of the deltoideus, lateral head of the triceps brachii, and biceps brachii, and fine-wire EMG data were collected from the supraspinatus muscle. Repeated-measures ANOVA tests were conducted followed by post hoc pairwise comparisons when significant main effects were seen (P < .05).

Data were collected from 12 adult large-breed dogs. Peak supraspinatus activity increased by 6.5% (95% CI, 0.1% to 11.8%) from 0% to 5% incline and by 5.7% (95% CI, 1.6% to 15.5%) from 5% to 10% incline. Average triceps muscle activity increased by 17.9% (95% CI, 0.6% to 3.7%) from 0% to 10% incline, by 12.5% (95% CI, 1.2% to 5.9%) from 5% to 10% incline, and by 9.3% (95% CI, 1.1% to 1.7%) from 5% to 10% decline. Peak triceps and average deltoideus activity followed similar trends. Biceps brachii activity showed no significant changes.

Muscle activities of the supraspinatus, triceps, and deltoideus all exhibited significant changes during incline and/or decline treadmill trotting. The biceps brachii was not significantly affected by any condition tested.

The findings support the use of incrementally increasing or decreasing levels of treadmill trotting to progressively load specific forelimb musculature in canine rehabilitation.