The purpose of this experiment was to investigate the welfare of pregnant mares kept in straight stalls and given only limited exercise, conditions that are similar to those encountered in the pregnant mare urine industry. Sixteen pregnant mares (eight in each of two years) were randomly assigned to two groups: Ex (exercised in a paddock for 30 min per day) or NoEx (exercised for one 30 min period every 14 days). The horses were housed in straight (or ‘tie’) stalls for six months and had ad libitum access to grass hay. Each horse's behaviour was recorded on videotape once per week for 24 h. The major behaviours were eating hay, standing, and stand-resting (head down and one hind limb flexed). There was no difference between the behaviours or the number of foot lifts per min of the Ex and NoEx groups in their stalls. Nine of 16 mares were not observed in recumbency throughout the whole of the six-month observation period, suggesting that horses with no previous experience in straight stalls may be reluctant to lie down. Thirteen of 16 mares dropped to their knees at least once, probably when they were REM sleeping while standing. There were no significant differences between the Ex and the NoEx mares in baseline plasma Cortisol levels or in Cortisol response to ACTH. Following 30 min of exercise, NoEx mares showed an increase in Cortisol from 5.0 to 5.4 μg dL−1, whereas Ex mares showed a decrease from 4.6 to 3.6 µg dL−1. The NoEx horses that had been confined for two weeks trotted more (NoEx = 22 [6-38; median and range]% of time; Ex = 2.4 [0-8.7]%) and galloped more (NoEx = 6 [2-8]%; Ex = 0 [0-4]%) than the Ex that were released daily, but walked less (NoEx = 17 [10-26]%; Ex = 35 [20-40]%) and grazed less (NoEx = 0%; Ex = 3 [0-12]%). Confined horses show rebound locomotion — that is, a compensatory increase — when released from confinement, indicating a response to exercise deprivation.

Anomalous aortic origin of the coronary arteries is associated with exercise-induced ischaemia, leading some physicians to restrict exercise in patients with this condition. We sought to determine whether exercise restriction was associated with increasing body mass index over time. From 1998 to 2015, 440 patients ⩽30 years old were enrolled into an inception cohort. Exercise-restriction status was documented in 143 patients. Using linear mixed model repeated-measures regression, factors associated with increasing body mass index z-score over time, including exercise restriction and surgical intervention as time-varying covariates, were investigated. The 143 patients attended 558 clinic visits for which exercise-restriction status was recorded. The mean number of clinic visits per patient was 4, and the median duration of follow-up was 1.7 years (interquartile range (IQR) 0.5–4.4). The median age at first clinic visit was 10.3 years (IQR 7.1–13.9), and 71% (101/143) were males. All patients were alive at their most recent follow-up. At the first clinic visit, 54% (78/143) were exercise restricted, and restriction status changed in 34% (48/143) during follow-up. The median baseline body mass index z-score was 0.2 (IQR 0.3–0.9). In repeated-measures analysis, neither time-related exercise restriction nor its interaction with time was associated with increasing body mass index z-score. Surgical intervention and its interaction with time were associated with decreasing body mass index z-score. Although exercise restriction was not associated with increasing body mass index over time, surgical intervention was associated with decreasing body mass index z-score over time in patients with anomalous aortic origin of the coronary arteries.

The beneficial effect of exercise restriction in preventing sudden cardiac death in children with aortic stenosis remains unclear. We report the case of a 15-year-old boy with congenital aortic stenosis who was resuscitated after sudden cardiac arrest during exercise. The case led to the new concept that exercise restriction may prevent not only unpredictable ventricular ischaemic events and associated arrhythmias but also progressive ventricular hypertrophy.