It’s easy to think of speedwork as one big bag of “fast” workouts you can go in and pick from on any given day. But race-specific training is more nuanced than that.
“Speedwork benefits every runner, regardless of race distance or goal,” Amanda Katz, RRCA-certified run coach and NASM-certified personal trainer previously told Runner’s World. But if you want those faster efforts to actually translate to race day, you need them to mimic the demands of your event. In other words, all races reward speed, but they don’t reward it in the same way.
Half and full marathon runners need to hold a strong, steady pace for a long time, while 5K and 10K athletes need to tolerate faster efforts closer to their ceiling for shorter durations. That distinction should guide the workouts you plug into your plan.
Once you know what kind of speed you need for race day, you can choose the workout that targets it. Here’s how to differentiate half and full marathon speedwork from 5K and 10K speedwork—and one go-to session to help you train more specifically for those goals.
Half and Full Marathon Speedwork
For marathoners, speedwork is less about improving your top speed and more about improving speed endurance. Focus on targeting your lactate threshold, which is the point at which your body starts accumulating fatigue-inducing byproducts of exercise faster than it can clear them. Threshold work helps you sustain a stronger aerobic pace without crossing into anaerobic territory too early… and therefore, sizzling out.
Marathon-pace efforts, tempo runs, long intervals, and faster segments built into long runs all train your aerobic system to work more economically, helping your race pace feel easier, Justine Williams Roper, PT, DPT, RRCA-certified run coach and founder of InHer Physique Pelvic Therapy and Wellness, previously told Runner’s World.
“Marathoners tend to ignore speedwork, and they shouldn’t,” Al Hernandez, RRCA level 2-certified run coach and founder of Mile Marker Coaching, previously told Runner’s World. “[Marathon success] comes down to efficiency, and some of that efficiency can only come when you’re doing speedwork,” Hernandez says.
5K and 10K Speedwork
Races like the 5K and 10K are still primarily aerobic, but they require you to run much closer to your top-end speed, compared to a half or full marathon. That’s why speedwork for these distances often focuses more on VO2 max, or the maximum amount of oxygen your body can take in and use during exercise. Improving this metric can help you sustain the fast paces that shorter races demand.
VO2 max workouts often include intervals at race pace or faster, such as 400, 800, or 1K repeats, or high-intensity hill intervals.
Workouts with shorter, faster reps—like 30 to 90 seconds almost all out—can improve turnover, meaning they help create quicker, more powerful strides, Roper says.
Matt Rudisill is an Associate Service Editor who has been with Runner's World since 2025. A Nittany Lion through-and-through, Matt graduated from Penn State in 2022 with a degree in journalism and worked in communications for the university's athletic department for three years as the main contact and photographer for its nationally-ranked cross country and track & field teams. Matt was also heavily involved in communications efforts for Penn State football, men's basketball, and women's gymnastics. In his role with Runner's World, Matt has interviewed Olympians, world champions, and countless experts in the field to create service content that helps runners of all ages and experience levels train smarter and race faster. When he’s not out jogging, Matt can be found tweeting bad takes about the Phillies or watching movies.