Effects of Real-Time Quantitative Feedback and Verbal Encouragement on Maximal Strength and Power During Squat Training in Young Men

Selecting an appropriate training stimulus is important for developing strength and power. This study compared real-time quantitative feedback (RF), verbal encouragement (VE), and no external stimulus (WS) during an 8-week squat-training program, with football training (FOO) as a comparison condition. Forty male university students completed the study (n = 10 per group). The RF, VE, and WS groups completed the same Smith machine squat program, whereas the FOO group completed football training. Smith machine squat one-repetition maximum (1RM) and maximal concentric power at 20, 30, and 40 kg were assessed before and after the intervention. Squat 1RM increased significantly over time across the sample, but the time × group interaction was not statistically significant, indicating no statistically significant differences in changes among the four groups. For maximal concentric power, significant time × group interactions were observed at 20 and 30 kg. At 20 kg, the real-time feedback group improved significantly more than the football group, while at 30 kg, the without-stimulus group improved significantly more than the football group. At 40 kg, the time × group interaction was not significant, although average power differed among groups. These findings indicate that changes in maximal concentric power varied according to the absolute load tested. However, the results did not demonstrate consistent superiority of real-time quantitative feedback or verbal encouragement over resistance training without external stimulation.