The Efficacy of Exercise Therapy for Non-Specific Chronic Low Back Pain According to the Fitt Principle: A Systematic Review With Meta-Analyses

OBJECTIVE: To evaluate the efficacy of exercise therapy interventions differing in frequency, intensity, type, and time (FITT) on disability in individuals with non-specific chronic low back pain (LBP). DESIGN: Intervention systematic review with meta-analyses. LITERATURE SEARCH: Electronic databases were searched from inception to March 2026. STUDY SELECTION CRITERIA: We included randomized controlled trials (RCTs) that enrolled adults with non-specific chronic LBP (>3 months), and compared exercise interventions differing in at least one FITT component, and reported disability outcomes. DATA SYNTHESIS: Random-effects meta-analyses were conducted for each FITT component. Certainty of evidence was assessed using the GRADE framework, and prediction intervals were calculated. A complementary analysis used a 0–100 disability scale with a 15-point improvement prespecified as the minimal clinically important difference. RESULTS: Seventy RCTs (n = 3,991) were included. High-frequency programs (≥3 sessions/week) showed statistically significant improvements in long-term disability compared with low-frequency programs (SMD = 0.29; 95% CI 0.09, 0.49; moderate-certainty). Sensorimotor short-term (SMD = −0.49; 95% CI −0.78, −0.21; very low-certainty) and long-term (SMD = −0.76; 95% CI −1.48, −0.03; very low-certainty), yoga short-term (SMD = −0.39; 95% CI −0.68, −0.10; moderate-certainty), and assisted exercise long-term (MD = −3.96; 95% CI −5.47, −2.45; moderate-certainty) demonstrated statistically significant reductions in disability compared with other modalities. CONCLUSION: In adults with non-specific chronic LBP, higher-frequency exercise programs were associated with improvements in disability. Sensorimotor, yoga, and assisted exercise may offer modest additional benefits. Given the low-certainty and lack of clinically meaningful effects, exercise prescriptions should prioritize patient preferences, feasibility, and long-term adherence rather than a single FITT component.