Incline and decline treadmill trotting produce electromyographic changes in specific canine shoulder muscle activity: implications for therapeutic exercise
Objective: To identify the effects of incline and decline treadmill trotting on forelimb muscle activity in dogs using electromyography (EMG). Methods: 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). Results: 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. Conclusions: 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. Clinical Relevance: The findings support the use of incrementally increasing or decreasing levels of treadmill trotting to progressively load specific forelimb musculature in canine rehabilitation.