There are currently no models of exercise that recruit and train muscles, such as the rat spinotrapezius, that are suitable for transmission intravital microscopic investigation of the microcirculation. Recent experimental evidence supports the concept that running downhill on a motorized treadmill recruits the spinotrapezius muscle of the rat. Based on these results we tested the hypothesis that six weeks of downhill running (-14°grade) for 1 hour/day, 5 days/wk at a speed of up to 35 m/min would: 1) increase whole body peak oxygen uptake (VO_2peak), 2) increase spinotrapezius citrate synthase activity and 3) reduce the fatigability of the spinotrapezius during electrically-induced 1 Hz submaximal tetanic contractions. Trained rats (n=6) elicited a 24% higher VO_2peak (in ml/min/kg; sedentary, 58.5±2.0, trained, 72.7±2.0, P<0.001) and a 41% greater spinotrapezius citrate synthase activity (in µmol/min/g; sedentary, 14.1±0.7, trained, 19.9±0.9 µmol/min/g, P<0.001) as compared with sedentary controls (n=6). In addition, at the end of 15 min of electrical stimulation trained rats sustained a greater percentage of the initial tension than their sedentary counterparts (control, 34.3±3.1%, trained, 59.0±7.2%, P<0.05). These results demonstrate that downhill running is successful in promoting training adaptations in the spinotrapezius muscle including increased oxidative capacity and resistance to fatigue. Since the spinotrapezius muscle is commonly used in studies using intravital microscopy to examine microcirculatory function at rest and during contractions, our results suggest that downhill running is an effective training paradigm that can be used to investigate the mechanisms for improved microcirculatory function following exercise training in health and disease.