Abstract
Background. Anterior cruciate ligament (ACL) reconstruction is frequently associated with persistent quadriceps weakness and reduced quality of life. Graded backward treadmill walking has emerged as a promising intervention to enhance neuromuscular rehabilitation.
Objective. To investigate the effects of graded backward treadmill training on quadriceps strength, quadriceps muscle mass, and quality of life in individuals after ACL reconstruction.
Methodology. Sixty participants (aged 18–45 years) who underwent ACL reconstruction using a semitendinosus graft were randomly assigned to five groups (A–E; n = 12 per group). Groups A–D performed backward treadmill walking at inclinations of 0°, 5°, 10°, and 15°, respectively. Group E served as the control group and received conventional rehabilitation. Training was conducted for 20 minutes per session, three days per week, for four weeks. Outcome measures included quadriceps strength (assessed using a dynamometer), quadriceps muscle mass (assessed by ultrasound), and quality of life (measured using the IKDC and ACL-QOL questionnaires). Statistical analyses were performed using analysis of variance (ANOVA) and non-parametric tests.
Results. All groups demonstrated improvements in quadriceps strength, muscle mass, and quality of life following the intervention. Group B exhibited the greatest mean improvement in quadriceps strength, whereas Group D showed the largest increases in quadriceps muscle mass and quality of life scores. Significant between-group differences were observed at baseline for quadriceps strength (p < 0.001) and at post-test for ultrasound-derived muscle mass (p = 0.010), IKDC scores (p = 0.033), and ACL-QOL scores (p = 0.016).
Discussion. The findings indicate that backward treadmill training led to improvements in quadriceps strength, muscle mass, and quality of life across all intervention groups. The superior strength gains observed in Group B suggest that moderate incline backward walking may be optimal for enhancing force production, whereas the pronounced increases in muscle mass and quality of life in Group D indicate that higher inclinations may be particularly effective for promoting muscular hypertrophy and psychosocial recovery.
Conclusion. Graded backward treadmill training following ACL reconstruction improves quadriceps muscle mass and quality of life, with higher inclinations showing greater effects. Further research is warranted to determine long-term outcomes and to identify optimal training parameters.
Key words
anterior cruciate ligament, backward treadmill walking, rehabilitation, quadriceps strength, quality of life