The use of motivation as a psychological ergogenic aid is commonly used as strategy in physical training in order to improve performance. Some previous studies have shown positive effects on physical
performance, especially in endurance activities. However, few studies have investigated the effects of motivational methods in strength exercises acute performance. Thus, the aim of this study was to
investigate the effects of verbal encouragement and visual incentive on strength training performance.
Eight healthy men experienced in resistance training in minimum six months participated this study (32.1±6.9 years). Subjects performed five tests of barbell elbow flexion exercise with an interval of
48 hours between tests. The tests followed the sequence: 1) one repetition maximum test (1RM); 2) 1RM confirmation; 3) control (no motivation); the tests 4 and 5 was performed in cross-over mode and
randomized (counter-balanced), being test with verbal encouragement (VE) or visual incentive (VI) (mechanical assistance simulation). In tests 3, 4 and 5, the subjects performed three maximal series
with 80% of 1RM with 90 seconds rest interval. It was registered the exercise performance by the number of repetitions performed and rating of perceived exertion (RPE) through the OMNI-RES Scale. A
descriptive analysis of average and standard deviation data was carried out. Shapiro-Wilk test was used to check normality of data. To check possible differences among the treatments of performance
and RPE the repeated measures ANOVA was used. The level of significance accepted was P≤0,05. To calculate Effect Size (ES) was used the Hedge’s g approach and data was shown with their respective 95%
Confidence Interval (CI). To classify the ES we used a qualitative scale developed by Cohen and to estimate of the probability of the superior outcome of one treatment over another we used the common
language ES statistic.
The performance were not different among tests (control: 4.8±1.8; VE: 5.0±2.3; VI: 4.7±1.7) and ES [control x VE=0.09 (CI=1.10 to -0.92); control x VI=-0.05 (CI=0.80 to -0.91); VE x VI=-0.14 (CI=0.85
to -1.13)]. Similarly, the RPE did not show difference among intervention (control: 7.8±0.8; VE: 8.0±0.5; VI: 8.3±0.6) and ES [control x VE=0.28 (CI=0.61 to -0.04); control x VI=0.67 (CI=1.02 to
0.32); VE x VI=0.51 (CI=0.78 to 0.24)]. For RPE, control treatment compared to VI showed a medium ES and 69% of probability of the subject presents a perceived exertion raise using the VI; VE compared
to VI showed a medium ES and 63.8% of probability of the subject presents a perceived exertion raise using the VI.
The VE and VI were not able to improve performance in strength training when compared to exercise without the use of motivation forms. Moreover, the VI could negatively modulate the perceived