Author(s): FISCHER, J., BURGER, C., SCHÖPFLIN, A., RODOPLU, C., KONRAD, A., Institution: UNIVERSITY OF GRAZ, Country: AUSTRIA, Abstract-ID: 1324

INTRODUCTION:
The range of motion (ROM) during a resistance training exercise has been shown to influence the hypertrophic outcome whereby partial ROM training at longer muscle lengths seem to show a benefit when compared to ROMs at different muscle lengths 1. Given these findings, it would be of interest to assess whether the specific emphasis within individuals resistance training routines correlates with differences in muscle mass. Thus, the aim of this research was to correlate the strength levels, measured by the 10-repetition maximum (10RM), across different ROMs in the barbell bench press exercise (BP) to the cross-sectional area (CSA) of the muscles primarily engaged in the exercise.
METHODS:
Ten resistance trained participants (average age 27.2 ± 4.0 years,) volunteered in this study and visited the laboratory on two separate days. The first day was used to record the CSA with ultrasound imaging using the Aixplorer V12.3 ultrasound system (Supersonic Imaging, Aix-en-Provence, France) and to familiarize the participants with the BP and its different ROMs. Ultrasound images were captured in a longitudinal panoramic view for the pectoralis major at two sites, medial and lateral 2 and in a transversal panoramic view for the triceps brachii long head at two sites, proximal and distal to the acromial process 3. On the second day, participants were assessed for their 10RM of the three types of BP variations, a full ROM and two partial ROMs (lower half and upper half of the full ROM). Pearsons correlation was applied to examine relationships between 10RM strength assessments and muscle CSAs.
RESULTS:
Pilot data analyses revealed significant correlations between the full ROM BP variation and the medial CSA of the pectoralis major (r = 0.674, p = 0.023). Furthermore, significant correlations were found between the lower ROM BP variation with the medial (r = 0.821, p = 0.002) and lateral (r = 0.742, p = 0.009) CSA of the pectoralis major. Additionally, neither upper ROM BP or triceps brachii showed any significant correlations.
CONCLUSION:
Correlations between 10RM strength levels and CSA of the pectoralis muscles were only found for the full ROM and lower ROM BP variations. For the upper ROM BP variation, no correlation was found for any of the investigated muscle locations. These findings add to the expanding body of evidence highlighting the importance of the stretched position in resistance training 4 as individuals who demonstrated greater strength in the lower bench press variation also showed larger cross-sectional area of the pectoralis major. Future training studies will have to investigate potential causalities between higher CSA of the pectoralis major muscle and different ROM settings of the BP exercise.
1.Pedrosa et al., European Journal of Sport Science, 2022.
2.Hernández-Belmonte et al., Ultrasound in Medicine & Biology, 2022.
3.Matta et al., Journal of Strength and Conditioning Research, 2011.
4.Wolf et al., International Journal of Strength and Conditioning, 2023.