McKenzie Exercise Improves Physiological Response and Fitness: A Quasi-Experimental Study

Abstract

Introduction: Prolonged standing during packing work can lead to increased physiological load and decreased physical fitness, particularly affecting spinal flexibility and cardiovascular response. These factors can reduce work productivity and increase the risk of musculoskeletal disorders. Exercise interventions such as the McKenzie method may offer benefits in reducing physical strain and improving functional fitness among industrial workers.
Objective: This study aimed to determine the effect of McKenzie exercise on physiological workload, as indicated by the percentage of cardiovascular load (%CVL), and physical fitness, assessed through spinal flexibility using the Modified Schober Test, among packing workers exposed to prolonged standing postures.
Methods: This quasi-experimental study used a one-group pretest–posttest design involving 10 packing workers at CV. Cahaya Baru, aged 29–56 years, with an average work duration of 16.4 ± 14.1 years. Physiological response was measured using the percentage of cardiovascular load (%CVL), while physical fitness was assessed through the Modified Schober Test. Participants underwent McKenzie exercise sessions twice weekly for four weeks, totaling eight sessions.
Results: The intervention resulted in a mean reduction of 10.4% in %CVL, indicating improved physiological efficiency. Additionally, physical fitness, as measured by the Modified Schober Test, increased by 25.1%. Paired sample t-test analysis revealed statistically significant improvements in both parameters (p = 0.000; p < 0.05).
Discussion: These findings demonstrate that McKenzie exercises effectively reduce physiological workload and enhance spinal mobility, contributing to improved physical fitness in workers exposed to prolonged static standing postures.