Running 5K to Half Marathon: The Actual Process
I've been coaching runners for years, and the jump from 5K to half marathon is where most people either make it work or blow out an IT band. I learned this the hard way myself. Early on I followed a generic online plan and hit a stress reaction in my right tibia at week six because I increased my weekly mileage by too much, too fast. I dropped the volume back to the previous level, cross-trained on the bike for two weeks, and ran a thoroughness check with a sports doc before adding the distance back. It set back my goal race by three weeks but kept me healthy through the finish line. Here's the structure I actually use with runners who want to make this jump cleanly. The base block is eight weeks long. It assumes you can already run 5K in continuous effort at a comfortable conversational pace, and that your longest run before starting this cycle is around 8 kilometers without pain that lasts beyond the day.
Week one totals roughly 20 kilometers split into four runs. You add about 10 to 15 percent each week until week four, then you hold or dip slightly during a recovery week. Week five starts the second climb toward a peak of roughly 45 kilometers across five runs by week eight. The daily workout mix looks like this. Two easy runs per week fill most of the schedule. One of those easy runs is the long run, which grows each week until it reaches about 18 kilometers around week seven. The third weekly run is a quality session, usually threshold work or intervals. The fourth run is optional, and I recommend making it a very short recovery jog under 5 kilometers or skipping it entirely if you feel flat. Intensity distribution matters more than people realize. About 80 percent of your total weekly volume should sit below your lactate threshold pace. That means easy runs truly stay easy. If your easy 5K feels like a controlled 5K race effort, you're running too fast on the wrong days, and it will compound by week five or six.
Threshold work is typically 20 to 40 minutes just above lactate threshold pace, broken into segments like 2 times 10 minutes or 3 times 8 minutes with short recoveries. Intervals are shorter, often 6 to 10 repetitions of 800 meters to 1 kilometer at roughly 5K to 10K race pace with equal or slightly shorter recovery jogs. Pace targets are better estimated from recent race performances or time trial results than from feel alone. If your current 5K time is 30 minutes, your easy pace will be somewhere around 7:00 to 7:45 per kilometer, your threshold pace around 5:40 to 5:50 per kilometer, and your interval pace near 5:10 to 5:30 per kilometer. Your half marathon goal pace depends on your target finish time, but for most beginners aiming to finish, somewhere between 6:30 and 7:30 per kilometer is realistic once the base block is done.
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How The Weeks Actually Progress
Week one keeps things gentle so your tendons and bones adapt before the harder sessions begin. Monday easy 4 kilometers. Tuesday threshold 4 times 5 minutes at tempo pace with 90-second jog recoveries. Wednesday easy 5 kilometers. Thursday easy 4 kilometers. Friday long run 7 kilometers. Saturday optional recovery 3 kilometers or rest. Sunday rest. Week two adds distance to the long run and holds the quality work similar. Monday easy 4 kilometers. Tuesday threshold 3 times 8 minutes at tempo pace with 2-minute recoveries. Wednesday easy 5 kilometers. Thursday easy 5 kilometers. Friday long run 9 kilometers. Saturday optional recovery 3 kilometers or rest. Sunday rest.
Week three pushes the long run further and introduces slightly longer interval work. Monday easy 5 kilometers. Tuesday intervals 8 times 800 meters at 5K race pace with 90-second recoveries. Wednesday easy 6 kilometers. Thursday easy 5 kilometers. Friday long run 11 kilometers. Saturday optional recovery 4 kilometers or rest. Sunday rest. Week four is a reduction week. Total volume drops by roughly 20 to 30 percent compared to week three. This is where people make mistakes by keeping intensity the same and only cutting distance, which still leaves sharp fatigue. I usually keep the quality session but shorten it by a third, and I shorten the long run by a kilometer or two. Recovery week total mileage might sit around 14 kilometers instead of the previous week's 21. Week five starts the second build phase. Monday easy 5 kilometers. Tuesday threshold 3 times 10 minutes at tempo pace with 2-minute recoveries. Wednesday easy 6 kilometers. Thursday easy 5 kilometers. Friday long run 13 kilometers. Saturday optional recovery 4 kilometers or rest. Sunday rest.
Week six continues the climb. Monday easy 5 kilometers. Tuesday intervals 6 times 1 kilometer at 5K to 10K pace with 90-second recoveries. Wednesday easy 6 kilometers. Thursday easy 6 kilometers. Friday long run 15 kilometers. Saturday optional recovery 4 kilometers. Sunday rest. Week seven peaks before the final taper. Monday easy 6 kilometers. Tuesday threshold 4 times 8 minutes at tempo pace with 2-minute recoveries. Wednesday easy 6 kilometers. Thursday easy 5 kilometers. Friday long run 17 kilometers. Saturday optional recovery 4 kilometers or rest. Sunday rest. Week eight is the taper. Volume drops sharply while keeping a couple of short, sharp efforts to preserve leg speed without accumulating fatigue. Monday easy 4 kilometers. Tuesday short intervals 5 times 400 meters at roughly 5K pace with easy recoveries. Wednesday easy 4 kilometers. Thursday very easy 3 kilometers or rest. Friday long run 10 kilometers. Saturday easy 3 kilometers or rest. Sunday race day.
The total weekly mileage ranges from roughly 20 kilometers at the start to about 45 kilometers at the peak. The long run progression goes from 7 kilometers to 17 kilometers, which covers most of the half marathon distance demand in a way that stresses joints gradually rather than all at once.
Where People Go Wrong
The most common error is treating every run as training. When your easy runs drift into moderate effort, your recovery slows down and your quality sessions lose effectiveness. HR monitors help here if you know your zones. Easy runs should mostly stay below 70 to 75 percent of maximum heart rate for most recreational runners. If your watch shows you sitting at 80 percent on a flat 5K jog, you're going too fast. Another frequent mistake is increasing weekly volume by more than 15 percent in any single week. A jump from 25 kilometers to 35 kilometers looks generous but it stresses the same tissues repeatedly without giving them time to rebuild. I cap most of my runners at a 10 to 12 percent weekly increase during the build phases, with the recovery week included as a natural brake. Skipping the recovery week entirely is a third issue. The plan fails if you run week three hard, then immediately run week five hard again. The dip in week four is where adaptation actually consolidates. Without it, fatigue stacks and performance drops heading into the final build.
The optional Saturday run is also where people choose the wrong option. If you feel heavy legs, poor sleep, or elevated resting heart rate in the morning, skip it. The benefit of an extra short jog is small compared to the cost of adding fatigue before the long run.
Daily Nutrition And Hydration Basics
Carbohydrate intake should rise as weekly volume rises. During the lower volume weeks, a typical target is around 3 to 4 grams of carbohydrate per kilogram of body weight per day. During peak weeks, most runners do better at 5 to 6 grams per kilogram. Protein stays fairly steady around 1.4 to 1.7 grams per kilogram daily to support repair. Hydration isn't complicated but it does need daily tracking during heavy weeks. Urine color near pale yellow is a practical target. During runs longer than 75 minutes, taking in roughly 30 to 60 grams of carbohydrate per hour from gels or drinks becomes useful, especially on long run days when you're simulating race fueling needs.
Footwear And Gear
You don't need fancy gear to complete this plan. A pair of daily trainers with reasonable cushion and a shoe that fits without hot spots is enough. Replace shoes after roughly 600 to 800 kilometers of total wear. Rotating between two pairs of shoes extends their lifespan and can reduce minor tissue load over time because the midsole compression patterns alternate slightly. Socks matter more than most runners admit. A thin synthetic or wool blend sock reduces blister risk significantly compared to cotton. For the long runs, a light anti-chafe balm on common friction points saves a lot of unnecessary pain.
Race Week Adjustments
The final week before the half marathon is mostly about reducing volume while keeping the legs alert. Short strides or a few quick 100-meter bursts during warmups are fine and actually helpful. You do not need to add extra miles to feel prepared. Most runners feel sluggish if they try to cram one last hard week before race day. On race morning, a small carb meal about 2 to 3 hours before start is reliable. Something like oatmeal with banana and a little honey gives steady energy without sitting heavy. Bring the same shoes and socks you've used during your longest training runs. Changing gear on race day introduces unpredictable variables that rarely help.
When This Plan Doesn't Work
If you have a history of stress fractures, plantar fasciitis that hasn't resolved, or persistent knee pain that changes your gait, this standard progression is too aggressive. In those cases, a longer base phase with more walking breaks during the long run, or a swap to a graded return-to-run protocol under a physical therapist's guidance, is safer. If your current 5K time is slower than about 40 minutes and you have no structured running background yet, building a separate 8-week base first will improve your odds of finishing the half marathon cleanly. The jump from zero consistent running to a half marathon schedule in one go tends to break something, usually the lower legs or the motivation.
Tracking And Adjustment
Keep a simple log with date, distance, perceived effort from 1 to 10, and any pain that appears during or after the run. When you see perceived effort trending upward for the same pace across three consecutive workouts, reduce the next session's volume by 10 to 15 percent or swap the quality work for an easy run until the trend flattens. Resting heart rate measured first thing in the morning can flag accumulated fatigue. If your typical morning resting heart rate sits near 55 beats per minute and suddenly climbs to 62 or higher for two consecutive days, take an extra rest day or replace that day's run with a walk or bike session. Small adjustments like this prevent bigger setbacks later. This approach is straightforward and unglamorous, which is why it tends to work. The progressions are modest, the easy days stay easy, and the plan includes the built-in recovery week that most beginners skip. Follow it closely for the first four weeks, then adjust based on how your legs respond rather than how the calendar says you should feel.
