Rating of perceived exertion (RPE) is a simple, validated, measure of physical effort, largely reflecting heart rate (HR). However, RPE is being replaced by continuous HR monitoring to quantify internal loads which maximize performance and enhance recovery. PURPOSE: Primary aim: assess relationships between RPE (athlete and coach) versus HR during football practice. Secondary aims: quantify internal load via HR assessments of training impulse (TRIMP) and recovery. METHODS: Data represents pre-season testing, in an ongoing study. Twenty-nine collegiate male football players (age=20±2years; body mass index= 34±6kg/m²; weight=118±20kg) and 3 coaches volunteered to participate. Each athlete was pre-assigned a HR monitor for the first 7 days of football camp. All participants underwent a 3-minute quick recovery test (QRT). HR monitors were then worn during practice. Athlete HR, TRIMP, %heart rate reserve (%HRR), %heart rate max (%HRmax) were recorded and visible only to researchers. Immediately following practice, all athletes and coaches were asked to assess RPE for the entire training session (sRPE) using the Borg CR-10 scale. %HRmax and %HRR were transformed to scale from 1-10, to match the Borg CR-10. Significance set at p<0.05. RESULTS: Training sessions over this 7-day period, lasted 145.8±33.7 minutes. When weekly data were combined, significant overall correlations (pairwise;N=187) were noted between %HRR versus: %HRmax (r=0.84;p<0.0001), athlete sRPE (r=0.30;p<0.0001) and head coach RPE (r=0.30;p<0.0001). Athlete sRPE was correlated with one coach sRPE (r=0.30;p<0.0001). Athletes were then subdivided into Big, Combo, and Skill position groups. Two-way ANOVA for sRPE between athletes, coaches and %HRR demonstrated a significant interaction effect (F=15.2;p<0.0001;22.8%), time effect (F=36.4;p<0.0001;13.6%), and position effect between groups (F=26.1;p<0.0001;6.5%). TRIMP decreased over time, with a significant time effect (F=23.7;p<0.0001;33%) and position effect (F=5.4;p=0.005;2.5%). Trend for QRT to dip on Day 2, then increase over time. CONCLUSIONS: Athletes and one coach significantly predicted training effort (HR) during practice. However, the variance was small (9%) and sRPE remained steady despite decreased training load and increased QRT scores (trend) over time.