Author(s): TSOUKOS, A., BOGDANIS, G.C., Institution: UNIVERSITY OF ATHENS, Country: GREECE, Abstract-ID: 710

INTRODUCTION:
The range of motion has been defined as the degree of movement that occurs at a given skeletal joint during exercise [1], and its influence on force and power generation has been examined by comparing: (a) the full ROM (fROM), that is to move the barbell or the external resistance as far as anatomically possible with(b) partial ROM (pROM), that is a predetermined part of ROM within the fROM spectrum [2]. Research has shown different kinetic responses when performing resistance exercises at different ranges of motion [3]. However, no study has examined changes in peak force during repetitive sets to failure with different ranges of motion. Therefore, the aim of the present study was to examine the peak force responses during three sets to failure in the bench press exercise with different ranges of motion.
METHODS:
Ten men performed three sets to failure with maximum intended velocity in the bench press exercise on a Smith machine against a relative load of 65% of maximum with three different ROMs (a) Full ROM (FULL); elbow ROM from 78.4 ± 12.1o to full extension), (b) Bottom ROM in which the barbell was moving at the bottom half of the bench press (BOTTOM, elbow angle from 77.3±8.8o to 127.5± 8.7o) and (c) Top ROM (TOP) in which the barbell was moving at the top half of the bench press (TOP; elbow angle from 114.3±4.2o to full extension). Peak force [4] was recorded at the initial and final repetitions of each set using two dual-axis force platforms at a sampling frequency of 1000 Hz. Peak force efficiency (PFE) was calculated using the following equation: PFE = Peak Force x Barbells weight-1. The closer to 1 the better the efficiency. Significance was set at P<0.05.
RESULTS:
The relative lifting load was greater during TOP compared to FULL and BOTTOM (p<0.01). The three-way ANOVA [ROM (FULL, TOP, BOTTOM) x SET (1,2,3) x PART (INITIAL, LAST)] showed a significant interaction for peak force (p<0.01; η2=0.33). Tukey’s post hoc tests indicated that peak force was significantly higher in TOP compared to FULL (from 13.4% to 21.8%) and BOTTOM (from 29.4% to 39.5%). Also, peak force was higher in FULL ROM compared to BOTTOM (from 8.0% to 18.9%) in all sets and parts (p<0.001). Peak force decreased from the initial to the final repetitions in all sets during the FULL (p<0.01), in the 1st and 3rd set during the TOP (p<0.01) and in the 1st set only during the BOTTOM (p=0.05). PFE was significantly different between all conditions (FULL=1.10, TOP=1.06, BOTTOM=1.00).
CONCLUSION:
Peak force was greater during TOP compared to FULL and BOTTOM. Also, changes in peak force during FULL were greater compared to BOTTOM. These results might be due to better peak force efficiency (PFE) that the participants showed during the BOTTOM.
REFERENCES:
1. Schoenfeld BJ, Grgic J. (2020).
2. Newmire DE, Willoughby DS. (2010).
3. Clark, R. A., Bryant, A. L., & Humphries, B. (2008).
4. Lander, J. E., Bates, B. T., Sawhill, J. A., & Hamill, J. (1985).