Background: Marathon running is becoming more popular among middle-aged people who have no prior running experience. Improper or incomplete knowledge increases the risk of injuries in amateur runners. Individuals with spinal instability experience alteration in balance control while walking as well as running which in turn results in asymmetrical bodyweight distribution throughout the lower extremity. This changes the pattern of running leading to injuries of hips, knees, and ankle. Methods: The objective of the study was to correlate spinal instability with ankle injuries in amateur marathon runners. In this study, both male and female amateur marathon runners between the age group of 20 and 45 years with normal body mass index (BMI) were chosen and individuals with the previous surgery as well as degenerative diseases of spine and ankle fractures were ruled out. Spinal instability tests were carried out on amateur marathon runners with symptoms of instability. Subjects were asked questions related to ankle injuries. Outcome measures used were Oswestry Disability Index (ODI) and tests for spinal instability. Results: About 57% of participants were tested positive for the passive lumbar extension test and 42% of participants were tested positive for the prone instability test. There was the presence of ankle pain (68%), ankle swelling (24%), heel pain (60%), blisters (42%), ankle sprain (28%), and strain (26%) in selected participants. There were 68% runners with minimal disability and 32% runners with moderate disability. Conclusion: Amateur marathon runners with spinal instability had the presence of ankle injuries like ankle pain, ankle swelling, heel pain, blisters, ankle sprain, and strain. Based on the test performed and interpretation of the ODI and after correlating spinal instability with ankle injuries, we concluded that spinal instability increases the risk of ankle injuries in amateur marathon runners.