The Effect of an 8-week Resistance Training Intervention on the Cross-Sectional Area of the Rectus Femoris

Authors

Kornkanok Sophonsakulrat, Texas Tech UniversityFollow
Payton E. Miller, Texas Tech UniversityFollow
Corie N. Smith, Texas Tech UniversityFollow
Kat A. Adcock, Texas Tech UniversityFollow
Karley Rayfield, Texas Tech UniversityFollow
Canyon Massengale, Texas Tech UniversityFollow
Jessica Jones, Texas Tech UniversityFollow
Laura Roden, Texas Tech UniversityFollow
Avery Pickrell, Texas Tech UniversityFollow
Grant M. Tinsley, Texas Tech UniversityFollow
Jacob A. Mota, Texas Tech UniversityFollow

Abstract

Skeletal muscle hypertrophy is a key adaptation to resistance training, yet the time when measurable growth occurs remains unknown in previously untrained women. Evaluating hypertrophic changes over a short intervention period has important implication for training adaptations and program design. PURPOSE: The purpose of this study is to quantify the time course of muscle size cross sectional area (CSA) and morphological adaptations of the rectus femoris (RF) following 8-weeks of resistance training in previously untrained, college-aged women. METHODS: Twenty-two healthy, untrained female participants (age, 18-35, BMI, 22.65±2.61 kg/m²) were randomized to either an 8-week resistance-training group (TRAIN) or control group (CON). The TRAIN group completed a twice weekly, progressive lower-body program (flywheel deadlift, barbell front squat, leg press, and leg extension). Progression of the loads corresponded to the maximum load that each participant could perform for 4 sets of 8-12 repetitions. If the prescribed loads and repetitions were completed, ~2.3kg were added for the subsequent training session. Both groups completed 6 laboratory testing sessions, separated by 2 weeks. Every testing session included ultrasound imaging of the rectus femoris along with body composition and neuromuscular assessments. Images at 50% of the rectus femoris were taken with brightness-mode ultrasound and an open-source software (ImageJ) was utilized to analyze the CSA of the muscle. A linear mixed effect model was employed with group, time (PRE vs POST), and their interaction as fixed effects. Random effects included random intercepts for individual participants. RESULTS: Outcomes indicated a significant increase in the RF CSA in the TRAIN group but not CON, yielding a significant group by time interaction (B = 58.89 cm², t = 2.75, p < 0.05). CONCLUSION: Detectable size adaptations of the RF occurred within just 8 weeks of resistance training in previously untrained women. These findings refine expectations for early muscular adaptations and reinforce the effectiveness of short-term resistance training for initiating measurable muscle growth in novice female populations.

Recommended Citation

Sophonsakulrat, Kornkanok; Miller, Payton E.; Smith, Corie N.; Adcock, Kat A.; Rayfield, Karley; Massengale, Canyon; Jones, Jessica; Roden, Laura; Pickrell, Avery; Tinsley, Grant M.; and Mota, Jacob A. (2026) "The Effect of an 8-week Resistance Training Intervention on the Cross-Sectional Area of the Rectus Femoris," International Journal of Exercise Science: Conference Proceedings: Vol. 2: Iss. 18, Article 244.
Available at: https://digitalcommons.wku.edu/ijesab/vol2/iss18/244