Regular monitoring of the heart rate (HR):speed relationship may help evaluate response to training and aid in the early detection of problems. This relationship is normally determined using a treadmill or via a ridden test conducted outside on a track. Simple practical alternative methods to obtain this relationship without access to a treadmill or a track could be of value in the field. To evaluate whether the HR:speed relationship could be determined via an indoor ridden test or a lunge test, HR was monitored on two occasions at least 3 h apart, in 12 adult horses (mixed breed) in a familiar environment during a 5 or 7 m radius circle lunge (unridden) test (5LT or 7LT) and an incremental (ridden) test (RT) on the same day. The RT comprised two ridden laps of the perimeter of a 60 × 40 m indoor school at walk, three laps at trot, three at medium canter and four at fast canter (all on the right rein). The speed of each lap was recorded. The LT comprised lunging for 2 min on each rein at walk, trot and canter. Speed was determined from the number of laps completed and measurement of the distance travelled. HR and speed were highly correlated in both lunge and ridden tests (both r = 0.99 ± 0.01). V140 on the ridden test (5.2 ± 0.6 m s− 1) was significantly greater than on the pooled lunge test data (4.4 ± 0.6; P < 0.0001). There was a negative correlation between recovery HR at 2 min following either the LT or RT and V140 (P < 0.05). The slope of the HR versus speed relationship and V140 were not different between RT and 7LT, but were significantly different from those of the 5LT (P < 0.05). V140 was always lower on the lunge tests compared with the ridden test. This suggests that, in this study, lunging without a rider increased the metabolic demand above that for being ridden at a similar speed. V140 determined by the 7LT gave the closest approximation to the V140 determined by the RT. The HR:speed relationship can be obtained either from riding an incremental test in an indoor school or from an unridden lunge test.