30 day Window Risk of Injury, Shoe of the Week, Barkley Marathons & more

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Welcome to your weekly endurance briefing, courtesy of the Marathon Journal. Each Monday, we deliver essential updates and expert insights to keep you informed on the latest in running and competitive sports.

1. Shoe of the Week

The Kiprun Kip Storm Elite is a formidable French-engineered racer making its U.S. debut in April 2026, offering a unique dual-density "cupping" midsole ($250) that prioritizes stability without sacrificing the high-energy return of a carbon-plated super shoe. By encapsulating a bouncy PEBA core within a supportive TPU cradle and utilizing an aggressive 60% rocker geometry, the shoe eliminates the "wobbly" sensation common in high-stack racers, providing a grounded yet propulsive ride that feels efficient from 5K sprints to full marathons. Weighing in at a competitive 6.6 oz (187g) for a women’s size 8, it pairs elite technical features—like a seamless 3D knit upper for sockless comfort and nubbed "lockdown" laces—with a refined, neutral aesthetic that marks a sophisticated new era for the Decathlon-born brand on American soil. Read the full review at marathonjournal.com.

2. Research Spotlight: The 30-Day Window and Injury Risk

A massive study of over 5,000 runners reveals that the "10% Rule" for injury prevention is more specific than we thought. Research shows that injury risk spikes not based on weekly totals, but when a single session exceeds the longest run of the previous 30 days by more than 10%. Learn why your single longest run is the ultimate predictor of musculoskeletal durability and how to audit your month to stay in the safe zone. Read the full article at marathonjournal.com.

3. Barkley Marathons 2026: Brutal Valentine’s Day Start Ends With No Finishers

Last weekend, the 2026 Barkley Marathons tested runners with extreme winter conditions, unmarked trails, and massive elevation gains. With no finishers, the race highlights how navigation skill, mental resilience, and fatigue management are as critical as physical endurance in ultra-distance events. Read the full article at marathonjournal.com.

4. Ashley Paulson’s 100-Mile World Record at ~7:21 Pace Redefines Speed Over Extreme Distance

A women’s 100-mile world-record performance by Ashley Paulson sustained roughly 7:21 per mile for more than 12 hours on a flat loop course, redefining the relationship between speed and extreme endurance. Beyond the headline time, the effort underscores the decisive roles of aerobic efficiency, fueling precision, muscular durability, and pacing discipline in preventing late-race collapse. For marathoners and ultrarunners alike, it demonstrates why speed development remains foundational even at the longest distances. Read the full analysis for key lessons and performance insights at marathonjournal.com.

For more deep-dives and the latest in global running news, join the community at MarathonJournal.com.