84 Effects of incremental conditioning and supplemental dietary tryptophan on pre, mid, and post-exercise heart rate and respiratory rate in sled dogs

Abstract

Abstract Repetitive bouts of resistance and aerobic exercise can have dramatic effects on whole body physiology. Dietary tryptophan supplementation supports protein turnover and serotonin production, which assist in responses to exercise. The objective of this study was to investigate the effects of a 12-week incremental exercise regimen and supplemental dietary tryptophan on pre-, mid-, and post-exercise heart rate and respiratory rate in sled dogs. Sixteen dogs (mean age of 4.8 ± 2.5 years, body weight 24.3 ± 4.3 kg) were blocked for sex, age, and body weight, and randomly allocated to a control diet or the control plus tryptophan diet (tryptophan to large-neutral-amino-acid ratio of 0.075:1). All dogs participated in a 12-week conditioning regimen with controlled exercise challenges at week -1 and subsequently every 3 weeks. Electrocardiogram electrodes and thoracic rib bands were worn to record heart rate and respiratory rate (EMKA Tech., Falls Church, VA, USA) prior to, during, and following each exercise challenge. A trans regression, mixed, and correlation model were used where appropriate to assess the fixed effects of treatment and week, and explore linear relationships between recovery time and week in SAS (v 9.4). No differences were found in heart rate between treatment groups for any training level (P > 0.10). Working, recovery, and time required for heart rate to recover post-exercise decreased from week -1 to week 11 (P < 0.05). Correlation analysis indicated that treatment dogs recovered respiratory rate faster post-exercise compared to control (r = -0.421, P < 0.05). Resting, recovery and time required for respiratory rate to recover post-exercise decreased from baseline to week 11 (P < 0.05). This data suggests improvement in cardiorespiratory fitness was observed over 12 weeks of training and that tryptophan may support respiratory function during exercise recovery.