Does Running Get Easier? What Science Says
April 4, 2024
Most likely, if you are reading this article or anything on this website, you have run a half marathon or want to run a half marathon. The half marathon is one of the most popular racing distances. As popular as half marathon races are, you likely find just as many half marathon training plans online. Some plans are well-developed; others are a hodgepodge that may or may not have been generated by an AI system. How do you know if you have a half marathon training plan that will help you reach your goals?
First, it’s important to note that individual training response varies. A plan that works for you may not work for your training partner – or for you a few years later. The goal of this article is to help you understand the key components of a half marathon training plan so that you can choose the most appropriate plan for you in each training cycle.
A 2020 study in the Scandinavian Journal of Medicine and Science in Sports studied the correlation (using linear regression) between training practices and half marathon performances in 556 runners. The researchers found that higher training volumes (>32 km/20 miles per week) and a long run >21 km/13 miles resulted in faster finish times.
Physiological performance predictors include running economy, VO2max, and anaerobic threshold, according to a 2022 review in the Journal of Muscle Research and Cell Motility. Given the half marathon is highly aerobic in its energy demands, the impact of these markers of aerobic capacity makes sense.
Based on that research, a half marathon training should develop aerobic capacity, lactate threshold (as defined in popular running lingo, similar to anaerobic threshold), critical speed (another measure related to anaerobic threshold), and running economy. A half marathon training plan should feature easy runs, increasing weekly mileage, and workout at or near lactate threshold or critical velocity.
Based on an understanding of what physiological variables and training factors influence half marathon performance, we know that certain types of runs can be part of a half marathon training plan.
Important caveat: this list does not mean you should exclude other types of runs. Short intervals, hill workouts, and other types of workouts have their place in training. Individual runners respond to various workouts differently based on their muscle fiber typology and other factors. This list means you may want to deliberately include these workouts, but it does not mean you should skip other types of workouts.
Whether you are a novice or an experienced runner, easy runs will constitute a majority of your training plan. The body of evidence over the past 15 years reached a consensus that approximately 80% of the total running volume is done below aerobic threshold (conversational effort). (Not sure how easy your easy runs should be? Read more here.)
Easy runs support aerobic development. Easy running (in zone 2) encourages mitochondrial biogenesis and angiogenesis – fancy words that translate to enhanced oxygen delivery and aerobic metabolism in the muscles. Additionally, easy running places less stress on the musculoskeletal system and uses less glycogen, which allows you to run more mileage. As discussed above, higher training volumes are correlated with faster finish times. Running easy allows you to run more, and running more allows you to race faster.
Easy running has the most significant long-term effect on long-distance running performance, including the half marathon. A 2021 study published in the Journal of Strength and Conditioning Research found a high correlation (r = 0.72 p<0.001) between easy runs and running performance.
Easy runs remain important even in an advanced half marathon training plan. As an athlete progresses (after 5-7 years of training), easy runs still are one of the most significant factors in performance (r=0.68, p<0.001). Workouts such as tempo runs and short intervals become more important after 5-7 years, but not at the expense of easy runs.
A first-time half marathoner will likely do more than 80% of easy running. Depending on various factors, they may even only do easy runs leading up to their first half marathon.
Threshold running is done at a moderately-hard intensity – approximately what you could sustain if you were racing for one hour. For elite runners, threshold pace is virtually half marathon pace. For most recreational runners, threshold is slightly faster than half marathon pace. Even if threshold pace is closer to 10K pace for you, it highly correlates with half marathon performance. (This article delves more into the science of threshold runs.)
If we look at the same 2021 study as cited above, threshold runs are the third most important variable in long-distance running performance, after easy running and total volume of running (r=0.50-0.58 over 3-7 years, p<0.001). The studies discussed earlier in this article reflect the importance of threshold running, as threshold runs improve both aerobic capacity and lactate threshold.
Threshold runs can be done as continuous tempos (typically 20-40 minutes) or as 3-15 minute intervals with short rest in between. Both types of threshold runs have a place in a half marathon training plan!
Critical speed (sometimes also called critical velocity is the new VO2max for interval training. This intensity zone provides a large upper-end aerobic stimulus without excessive fatigue. This intensity recruits the intermediary fast-twitch muscle fibers which are what your body uses when fatigued at the end of a half marathon. (You can read more about the science of critical velocity training here.)
Critical velocity is approximately the pace you could sustain if racing for 30-40 minutes. When you run intervals at critical speed, they will feel somewhat hard yet controlled. These are not gut-busting track workouts, but they are wildly effective for long-distance runners. (They are a common staple in Norwegian training and Canova-style marathon training.)
In my years of coaching experience, I have seen the data reflect the science: controlled-hard intervals improve half marathon race performance. Since fatigue and musculoskeletal stress are lower compared to VO2max intervals, many injury-prone runners can safely incorporate these. These intervals can range from 1-8 minutes and accumulate 15-30 minutes of time at intensity within a workout.
Strides are a staple in long-distance run training, and for good reason. These short accelerations provide continual reinforcement of running economy by stressing the neuromuscular system. However, since strides are so short (20-30 seconds), they place minimal stress on the musculoskeletal system. In a half marathon plan, strides should be part of weekly training from week one until race week. (This post explains how to do strides.)
As noted above, long runs are essential for half marathon training. If you are going to race for 1.5-2.5 hours, you need to prepare your body for those demands. Almost all half marathon training plans include weekly long runs. Long runs provide a bioenergetic, biomechanical, and neuromuscular stimulus. Your body responds with adaptations including enhanced aerobic metabolism, increased intermediate fast-twitch muscle fiber recruitment, better efficiency under prolonged loading, increased fat oxidation and glycogen sparing, and improved fatigue resistance.
For beginner half marathoners, the long runs should be solely focused on time on feet. For intermediate to advanced runners, a half marathon training plan may include a mixture of long runs at easy pace and long run workouts. Long run workouts can include surges, progressions, and miles at half marathon effort.
A first-time runner may build up to 10 to 13 miles in their half marathon training plan. Experienced half marathon runners may do longer runs, up to 15-16 miles, in preparation for their race.
If you glance at training plans online, you may see plans that spend 8 weeks or 16 weeks preparing for a half marathon. That is a large range! How many weeks you individually need to prepare for a half marathon depends on goals, training experience, and current fitness.
The better of a training base you have, the less time you need to prepare for a half marathon. Importantly, a well-rounded training base should include lots of easy running, strides, and some controlled workouts. An experienced runner with a robust aerobic base can spend 8-12 weeks preparing for a goal half marathon.
If you have only been doing easy running, you want to give yourself more time to safely introduce speedwork. You will want to allow 12-16 weeks to prepare for a half marathon. The exact time frame will depend on how long your longest weekly run currently is.
If you are a new runner, you will want more time to safely increase mileage for your first half marathon. Depending on your current training, you may want to spend 4-6 months preparing for a half marathon. 16 weeks is appropriate if you are running some, while six months or more is better if you are not running more than three miles at once. (The same applies to an experienced runner returning from a long training hiatus.)
Training intensity distribution refers to how much time you spend running in different training zones. Some plans favor high mileage and low intensity, while other plans more faster running.
Pyramidal training is a type of training intensity distribution that favors easy running and moderate-intensity workouts, with minimal time spent at VO2 max or higher. In pyramidal training, approximately 80% of running is easy. Of the remaining 20%, approximately 15% is in moderate to mod-hard (threshold and critical velocity) and 5% is hard to very hard (VO2max, strides, etc.)
A 2022 review in the International Journal of Sports Physiology and Performance observed that most long-distance runners adopted a pyramidal approach, compared to middle-distance runners who preferred a polarized approach.
High-intensity VO2max intervals can have a place in half marathon training. However, they are not the primary workout for a majority of training. In my coaching experience, I have observed many runners respond well to some high-intensity intervals early on in training (about 8-12 weeks out from the race). Following 2-4 weeks of polarized training, the focus shifts to more thresholds and critical speed. This less-specific to more-specific approach is common amongst many training systems.
Beginner runners will focus on developing their endurance and being able to finish a half marathon. Once you are beyond that point, it is essential to progress your training plan. Intermediate to advanced runners will want a half marathon training plan with various workouts to help them reach peak performance.
Some ways to progress your half marathon training:
These weeks are just examples – they are not absolutes. The number of days you run, types of workouts you do, and weekly mileage will vary based on background, training response, and other factors.
Beginner:
Experienced:
As with any race distance, a training plan is part of the equation for a half marathon. A taper, individualized nutrition strategy, sound pacing strategy, and mental preparation all also impact the race outcome. For more information on half marathons, you can reference the following:
2 Responses
Thanks. As always, lovely clear advice. Thanks for taking so much care.
Love that you backed everything up by research. Thank you!