The purpose of this study was two-fold. In Specific Aim One, we examined the associations between education level, personal trainer credentials and characteristics, and knowledge of exercise science and personal training principles. In Specific Aim Two we examined associations between education, personal trainer credentials and knowledge of personal trainers with client retention. This study utilized a cross-sectional research design. An anonymous electronic survey was used to collect the data. Eligible participants (N=226) were individuals who were providing one-on-one personal training services for at least one client. All data were assessed for normality prior to data analysis. Descriptive statistics were used to evaluate sample characteristics. Mean and standard deviations, median and interquartile range [IQR] or frequency and percentages were reported for the sample characteristics. Bivariate associations were examined with dependent t-tests and one-way ANOVAs for normally distributed data. Mann- Whitney U and Kruskal-Wallis tests were used for non-normally distributed variables. The median knowledge score for the sample was 6.0 [3.00] points, out of a possible 24, with 92.5% of the sample scoring 10 or lower. Sex (Male/Female), education level, having a degree in the field, certification status (yes
o) and number of certifications were not associated with knowledge scores (p > 0.05). Years of experience in personal training was positively associated with mean knowledge scores (H(3) = 9.280, p = 0.026). Sex of the personal trainer, having a degree in the field (yes
o), the number of personal trainer certifications, the cost of training, the type of facility, the type of employment of the personal trainer and knowledge scores were not associated with client retention (p > 0.05). Education level (F3,87 = 8.176, p < 0.001), personal training certification (yes
o) (t38 = 2.277, p = 0.029), years of experience (F3, 87 = 3.169, p = 0.028), facility size (F4,84 = 8.049, p < 0.001), and exercise science degree type (F3,48 = 6.008, p = 0.001) were all associated with client retention. This study provides insight on knowledge retention of active personal trainers on subject matter deemed foundational by four certifying organizations. The findings should influence both the preparatory learning and well as continuing education approaches of both certifying organizations and institutions of higher learning.