# Why Runners Don't Make It to Marathon Start—and How to Train Smart Enough to Show Up

Marathon training breaks runners. Not metaphorically. Did Not Start (DNS) rates for marathons run higher than most endurance events, with training injuries and overtraining syndrome sidelining athletes weeks before race day. Runner's World examined the patterns behind these dropouts and consulted coaches to identify training modifications that keep runners healthy enough to actually toe the starting line.

The culprit isn't always bad luck. Overambitious mileage jumps, inadequate recovery, and ignoring early warning signs of injury cause most DNSs. Runners chase ambitious pace targets while simultaneously adding long runs without allowing adaptation time. The body breaks before the taper even begins.

Research on training load supports what coaches observe in practice. Sudden increases in weekly volume beyond 10 percent per week significantly elevate injury risk, particularly in the lower leg and knee. A runner who builds from 40 miles per week to 60 miles per week in two weeks bypasses the body's adaptation window. Tendons, bones, and connective tissue need time to strengthen alongside cardiovascular fitness. Muscle adapts faster than connective tissue. This mismatch creates the perfect conditions for stress fractures, tendonitis, and overuse injuries that force withdrawal.

The second pitfall involves skipping the easy runs. Coaches consistently emphasize that 80 percent of training should feel conversational. Many amateur marathoners reverse this ratio, turning easy runs into moderate efforts because they feel "unprepared" without constant intensity. This approach triggers accumulated fatigue without building the aerobic base that actually delivers race performance. The nervous system never recovers. Resting heart rate climbs. Sleep quality drops. The body signals distress through persistent soreness, elevated fatigue, and illness.

Marathon training also demands periodic testing and adjustment. Runners often lock into a predetermined plan without considering how their body responds to the stimulus. Skipping workouts, requiring extra recovery days, or noticing degraded performance in key workouts signals overtraining. Acknowledging these signs early allows for reduced volume or extended recovery windows before injury forces a DNS.

Coaches recommend building training around three principles to maximize the chance of a healthy start line arrival.

First, respect the 10 percent rule. Weekly mileage increases should not exceed 10 percent from one week to the next. This applies to long run increases as well. A 15-mile long run should not jump to 20 miles the following week. Instead, increase to 17 miles, maintain or reduce the following week, then build again.

Second, structure runs by effort level, not pace. Elite marathon coaches program runs as easy, moderate, or hard efforts rather than specific paces. This approach accommodates fatigue, weather, and individual response to training. An easy run stays easy regardless of GPS data showing slower times.

Third, build in scheduled recovery weeks every three to four weeks. Every third or fourth week should reduce total volume by 20 to 30 percent compared to the previous week. This allows the body to actually adapt to accumulated training stress and clear metabolic waste products. Recovery weeks reduce injury risk and boost performance when training resumes.

The final piece involves listening to external signals. Elevated resting heart rate, disrupted sleep, persistent soreness, or elevated stress markers indicate the nervous system needs recovery. Adding an extra easy day or reducing the next workout's intensity prevents the cascade that leads to DNS.

Runners who implement these strategies consistently arrive at marathon start lines feeling strong and confident. Those who ignore them often don't arrive at all.