The effects of hip flexion angle on quadriceps femoris muscle hypertrophy in the leg extension exercise.

Larsen, Stian; Kristiansen, Benjamin Sandvik; Swinton, Paul Alan; Wolf, Milo; Fredriksen, Andrea Bao; Falch, Hallvard Nygaard; van den Tillaar, Roland; Sandberg, Nordis Østerås

Abstract

This study compared the effects of 90° versus 40° hip flexion in the leg extension exercise on quadriceps femoris muscle hypertrophy. Twenty-two untrained men completed a ten-week intervention comprising two resistance training sessions per week with four sets of leg extension to momentarily failure. A within-participant design was used, with lower limb side randomly allocated to the 40 or 90° condition. Muscle thickness of distal and proximal rectus femoris and vastus lateralis were quantified via ultrasound. Data were analysed within a Bayesian framework including univariate and multivariate mixed effect models with random effects to account for the within participant design. Differences between conditions were estimated as average treatment effects (ATE) and inferences made based on posterior distributions and Bayes Factors (BF). Results indicated a greater hypertrophic response in the rectus femoris for the 40° condition, with 'extreme' evidence supporting a hypertrophic response favoring the 40° hip angle for the rectus femoris (BF > 100; p(Distal/ATE and Proximal/ATE > 0) > 0.999), and 'strong' evidence supporting no difference in hypertrophic response for the vastus lateralis (BF = 0.07). Therefore, both conditions could be viable options for increasing quadriceps femoris hypertrophy. However, when training for maximizing rectus femoris hypertrophy among untrained men, we suggest training with a reduced hip flexion in the leg extension exercise.

Citation

LARSEN, S., KRISTIANSEN, B.S., SWINTON, P.A., WOLF, M., FREDRIKSEN, A.B., FALCH, H.N., VAN DEN TILLAAR, R. and SANDBERG, N.Ø. [2025]. The effects of hip flexion angle on quadriceps femoris muscle hypertrophy in the leg extension exercise. Journal of sports sciences [online], (accepted).

• Journal Article Type: Article
• Acceptance Date: Dec 12, 2024
• Deposit Date: Dec 13, 2024
• Journal: Journal of sports sciences
• Print ISSN: 0264-0414
• Electronic ISSN: 1466-447X
• Publisher: Taylor and Francis
• Peer Reviewed: Peer Reviewed
• Keywords: Knee extension; Vastus lateralis; Rectus femoris; Hypertrophy
• Public URL: https://rgu-repository.worktribe.com/output/2619776