Date of Graduation


Document Type


Degree Name

Bachelor of Science

Degree Level



Animal Science


Dr. Charles Rosenkrans

Committee Member/Reader

Dr. Jeremy Powell

Committee Member/Second Reader

Daniel Potter

Committee Member/Third Reader

Dr. Charles Rosenkrans


Our objective was to determine whether administering low-level laser therapy before or after exercise had the greatest effect on biochemical markers of skeletal muscle fatigue in equines such as cortisol and blood lactate. Twelve quarter horses were divided into three groups: Group A received no laser therapy, Group B received laser therapy before exercise, and Group C received laser therapy after exercise. A Class II ERCHONIA ® PL500 handheld low-level laser was utilized for treatment with a wavelength of 635nm. Exercise was utilized using a horse walker system for 30 minutes five days a week for three weeks. Blood was collected via jugular venipuncture at time zero and then once a week for the remainder of the study. According to the results of this study, there is no evidence to suggest that laser therapy had a significant effect on equine cortisol or lactate, regardless if it was performed before or after exercise. However, there was an interaction between group and time for both lactate and cortisol. The results also showed that lactate increased as time increased as a result of lactic acid build up due to exercise, and cortisol decreased over time, which could be due to several possible variables such as weather. Several factors could have altered the results of this study, such as age, gender, weather, and diet of the equine subjects.


laser therapy, equines, cortisol, lactate, exercise physiology