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Hamilton, Janet S. M.A., ACSM-RCEP®, CSCS, PTA; Sorace, Paul M.S., FACSM, ACSM-RCEP®

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ACSM's Health & Fitness Journal 22(2):p 16-22, March/April 2018. | DOI: 10.1249/FIT.0000000000000373
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According to RunningUSA.org, the most popular road race distance in the United States is the 5 k, with more than 8.2 million finishers in 2016 (1). Second place is held by the half-marathon distance (13.1 miles), with 1.9 million finishers. Although the marathon gets all the glory in the press, it ranks well behind in fourth place, with only approximately half a million finishers in 2016. Participation in the half marathon has more than doubled in the past decade from a little more than 724,000 in 2006 to 1.9 million in 2016 (1). Historically, 60% of the finishers have been women, and 44% of finishers are older than 40 years (2). The increase in participation makes perfect sense because the distance, which still needs to be respected, is more achievable for many. The average finish time for males in 2015 was 2:04:00 (~9:28 per mile). For females, the average finish time was 2:22:21 (~10:52 per mile) (2).

Considering the growth in participation, it is likely that at least a portion of those runners are pushing to improve on a previous performance (finish time) at the distance. Training to improve a performance in a particular race distance may require a change in emphasis from what was done in training the previous time around. Regardless of the race distance, the basic training tenets are the same when trying to beat a previous performance:

  • 1) get the endurance needed to truly race (not just complete) the distance (e.g., greater weekly total mileage)
  • 2) improve running economy (e.g., hill running, running at target/goal race pace)
  • 3) improve race strategy and execution (e.g., avoid going out too fast in the early miles, insure optimum nutrition and hydration, undertake adequate taper before the race).

So, that first half marathon is in the books. How much can one improve? The answer to that depends at least in part on what preparation and training went into the previous attempt at the event. With very experienced athletes who are already running high mileage in training and have competed at the distance numerous times, only small improvements (0.5% to 1%) would be anticipated; but with somewhat less experienced athletes, improvements of 2% to 4% are reasonable to target in a given training cycle (e.g., 12 to16 weeks). Perhaps as much as 6% to 8% is achievable if the previous training was limited in scope and volume, the previous event was run at a conservative effort, the amount of time to train for the next event is ample, and the next event is run in more favorable conditions (e.g., cooler temperatures, faster course). To put that into simple math — one can take the previous finish time and divide it by 1.02 or 1.04 to get times approximating 2% to 4% improvement. The following will put this into perspective for both the male and female average finish time:


Targeting realistic improvements in performance (2% to 4% for the less experienced athletes, 0.5% to 1% or less for the highly accomplished athlete) will be more likely to insure that the training does not overload the athlete and limits injury risk.


Development of a training plan should always be individualized and respectful of the unique characteristics of each individual athlete. Each athlete brings a distinct set of characteristics to the table, including unique biomechanical, genetic, psychological, and social strengths and weaknesses, along with the standard physiological parameters of fitness that must be considered (3). In every training plan, enormous attention should be paid to the athlete’s current fitness (mileage base) as well as previous injury history and previous training history (years of training) and his or her unique response to a training stimulus. Simply put, stress + rest = growth, and stress without adequate recovery or rest leads to breakdown (4,5). Because each athlete responds individually to stress and recovers or fatigues at a different rate, training plans should be highly individualized. By closely tracking an athlete’s training and subsequent response, a coach can identify which athletes will benefit from additional rest or perhaps a change in training focus (4,5).


Much attention has been given to trying to devise the ideal method of measuring both fitness and fatigue, and although several methods have been shown to be promising, none are perfected (6). The common theme among these models is an attempt to quantify training loads based on a calculation that includes a quantification of intensity, duration, and frequency. In this way, a training session can be considered heavy if it is long or if it is of high relative intensity for that athlete, and these harder training sessions will be accompanied with an increased level of fatigue and a greater need for recovery. For this reason, it is wise to ensure that adequate recovery days are included in any training plan, and many plans will alternate a relatively easier day of training between the relatively harder ones. Fitness is built over time. Likewise, fatigue accumulates as an athlete reaches for new levels of fitness through either greater volumes or greater intensity of training. Getting the balance right requires a bit of finesse and is different for each athlete and indeed different for the same athlete in different phases of training or at different ages.


Look back at the peak training volume attained for the previous event. Achieving and maintaining a solid and consistent mileage base builds the foundation of fitness and strength to support the higher intensity speed work needed to really push a runner’s fitness and subsequent performance to the next level. Many first-time half marathoners may have completed their first half marathon on a mileage base of no more than 25 miles per week and a long run of 9 to 11 miles. Although one can certainly complete the distance on this base, racing for improved performance will require an increase in this total weekly distance. For an athlete starting from a 25-mile per week base, the first target might be to build their foundation to a consistent 35 to 45 miles per week, with long runs of 14 to 16 miles. As a point of comparison, elite half marathoners often log 100+ miles per week; training 6 days a week is common (7). Building total weekly distance takes time. Additions of training volume should be modest, and although there is no research to back it up, the oft-cited wisdom of “no more than 10% increase per week in total distance” is certainly shown through anecdotal evidence to be a worthwhile guideline to consider. As an athlete builds his or her base over a period of years, he or she gains a level of strength and resiliency that allows him or her to accumulate increasingly greater volumes of harder training without exceeding his or her ability to adapt. Training can be considered cumulative in that regard (3).

How much mileage is enough? The answer is different for each athlete, but the ultimate goal is to remain injury free and achieve maximum performance. If performance at 50 miles per week is not better than it was at 40, then those additional 10 miles per week simply increase the risk of injury and potentially fatigue the athlete and contribute to overtraining syndromes (6–8). Fitness and injury resistance are built over time, so with successive training cycles, an athlete will be able to gradually adjust and find his or her ideal mileage for maximum performance with minimum injury risk. In addition, ensuring adequate recovery by running at appropriate paces will help reduce risk of overtraining. It is important to keep in mind that even elite runners perform 70% to 80% of their training at relatively easy paces, which often are defined as marathon pace or slower (8,9). In super simplistic terms, think of your athlete’s training plan like baking a cake. The batter, the majority of his or her training, is easy miles and the icing, a small percentage of his or her training, is the hard running.


One way to establish an easy pace for an athlete is to use the data point of a recent 5 k race. A well-run 5 k represents about 97% of V˙O2 max, and training paces can be calculated back from there. Many online pace predictors are available, and most of them establish a range for easy pace that is roughly 70% to 79% of 5 k race pace (10). By individualizing training paces this way, rather than giving generic guidance like “slow down by 2 minutes per mile for easy pace,” the relative effort of each athlete is kept consistent despite their varying training paces. An example of this calculation for two very different athletes clearly demonstrates that a relative 79% effort for a runner who races a 5 k at a 7:44 pace is a little more than 2 minutes per mile slower than their race pace, whereas a runner who races at a 4:49 pace slows by only 1:17 per mile to achieve their correct easy effort.


Because the training load of a long run is, by definition, greater than that of the shorter runs, the athlete is encouraged to skew his or her easy pace a little slower in this range as the long run increases in length.


Once the mileage base is above 25 miles a week, addition of higher intensity running (e.g., speed work, hills, race pace miles) can usually be safely added. In addition to stimulating improvements in overall fitness (e.g., V˙O2 max), this type of training helps to improve running economy to enable the athlete to run faster at a given V˙O2. This higher intensity work can come in the form of faster paces or with the addition of specific hill-training techniques (8,11). Running economy is affected by strength, neuromotor patterns, and factors affecting metabolic efficiency or energy usage. Training that stimulates adaptation in these areas would be expected to improve a runner’s overall performance (8,9,12).


Although functional resistance training can be of benefit to build muscle fibers that are potentially undertrained in long-distance runners (fast-twitch fibers), the athlete’s exercises should be focused on multijoint moves that stimulate synergistic muscles in patterns similar to the demands of running. Exercises like squats, lunges, and even Olympic lifts would be preferable to exercises like leg extensions or leg curls, which tend to isolate one muscle group at a time in a fashion that is open, rather than closed kinetic chain. Each athlete is unique, but it would be wise to schedule specific strength training in the early phase of training (base building) and to avoid doing strength work on days when the athlete will be stressed by a higher mileage run (9). General guidelines would have the athlete performing resistance training no more than 2 to 3 times per week on nonconsecutive days, completing 2 to 3 sets per exercise, 8 to 12 repetitions per set.

Hill training can be considered one of the more specific forms of strength work that runners can perform because nothing simulates the neuromotor demands of uphill and downhill running the way actually running up and down hills does. Athletes unaccustomed to training on hills should be encouraged to start gradually with hills that are relatively short and not overly steep. Learning how to maintain a steady effort up the hill and how to run downhill well without “riding the brakes” is a worthwhile endeavor for all athletes but especially for those who have chosen a race that contains significant elements of elevation change. Hill training could be considered initially even in the base-building phase of training as the athlete is striving to increase his or her total weekly distance. As the athlete demonstrates that he or she is adapting well to the addition of hill work, he or she can gradually shift from the strategy of maintaining the same effort on the uphill to the strategy of maintaining the same pace running up the hill. By learning both of these strategies in training, and determining which strategy works best on which type and length of hill, the athlete will then be better prepared to execute the appropriate strategy on race day.

When considering speed training, it is important to appreciate that the volume of training at different intensities should be relative to the total mileage base to keep injury risk minimized and should be customized to the individual athlete’s needs (Table 1).

Suggested Upper Limits for Various Speed Work Intensities Based on Weekly Mileage

It is clear if you are able to perform a greater volume of speed work, you will achieve a greater improvement in performance; therefore, building an adequate endurance base to support a greater volume of speed work should be a primary goal in any athlete working to improve performance in a long-distance event (9). The focus of the speed work should be specific to the athlete’s individual needs and goal race, but generally speaking, there is an increased focus on specific race pace segments as the date of the event draws closer (9). With that in mind, speed work done at 5 k to 8 k and faster paces (high intensity) might be emphasized earlier in the training cycle with an increased focus on sustained efforts at half-marathon race pace (moderately high intensity) as the competition nears.


For novice athletes unaccustomed to including speed work in their training, a relatively low-key initiation to this can be done in the form of a “fartlek” run. The focus in these runs is to accelerate to some predetermined intensity for a short period and then settle back to an easy effort for recovery. For example, a runner might be instructed to warm up for 1 to 2 miles at easy effort, and then for the next 4 miles, alternate 1 to 2 minutes at what “feels like” approximately 10-k effort with 3 to 4 minutes back at easy effort. By framing the workout in terms of perceived effort rather than strict pace guidance, the athlete can begin to experiment with somewhat higher intensities while still allowing plenty of recovery between the faster intervals (8,9). These fartlek runs also are of value even to more experienced runners because they allow a relatively gentle reintroduction to slightly faster paces before resuming higher intensity track intervals.

Most athletes benefit from some form of higher intensity training performed 1 to 3 times per week (8); however, it is important to be sensitive to each athlete’s unique response to avoid pushing him or her into overtraining (4,6,13). Using different forms of intensity (hills, fartlek, high-intensity intervals, race-pace “tempo” runs), the athlete can insure that the overload he or she is applying does not exceed his or her tolerance. More experienced athletes with many years of training behind them can tolerate doing hills and speed work in the same week, whereas more novice athletes with fewer years of training may be better served to focus on intensity (hills or speed work) only once a week. A sample training plan is provided in Table 2 to illuminate the general principles of training progression, inclusion of rest days, and distribution of mileage throughout the week. The reader is advised that this is only a sample and will not be appropriate for all.

Sample Excerpt from a Training Plan for a Relatively Novice Runner Starting from His or Her Current Consistent Base of 30 Miles (~48 km) per Week with a Long Run of 11 Miles (~18 km). This sample demonstrates the principles of gradual progression and mileage distribution, as well as the incorporation of rest days. Some athletes require more rest/recovery than others, and this is noted with the option to change one of the “easy” days to an additional rest day if needed. This sample plan would only be appropriate for an athlete with a history of having done hills and some volume of speed training in previous training cycles for other race distances. Athletes who are less experienced should select one of the intensity workouts per week rather than attempting to include both (e.g., hills OR intervals rather than both starting in week 3)


Part of race strategy and execution is attention to the details of nutrition, hydration, and electrolyte balance. Ideally, the athlete will be following a sound nutritional plan in general so that adjustments before the long run or the race will be relatively minor. Research has shown that a period of carbohydrate depletion and aggressive carbohydrate loading may not be needed if the athlete is consuming an adequate amount on a regular basis (14).

The time to experiment and determine what works well is during training. Encourage the athlete to keep a log of his or her nutritional and hydration pattern on the day(s) before his or her long run as well as his or her consumption of fluids and fuel during the long run. Tracking body weight before and after a long run can provide valuable information about overall hydration status and sweat rate. Although it is anticipated that sweat rate will likely exceed fluid replenishment in long-duration exercise bouts, it is important to avoid both dehydration as well as overhydration. Loss of more than 2% to 3% of body weight during exercise has been shown to adversely affect performance, so maintenance of adequate hydration during training as well as during the race is important (14).

Although there is ample anecdotal evidence that a variety of nutritional practices are employed by athletes during training (low carbohydrate as well as more traditional diets), ample evidence supports the premise that performance is enhanced when glycogen depletion is avoided (14). Current recommendations are that athletes start their race with adequate glycogen stores and that if the exercise is anticipated to be 1 to 2 hours in duration, that supplementation during the activity with up to 30 g of carbohydrate per hour will improve performance. This rises to 30 to 60 g per hour for exercise duration of 2 to 3 hours (14). There is evidence to suggest that supplementing with a variety of rapidly oxidized carbohydrate sources (e.g., glucose, fructose, maltodextrin) will enhance carbohydrate uptake in the intestine (14).

One thing to consider is how frequently fluid and fuel may be available on race day and train with that in mind. For example, if an athlete is anticipating aid stations with fuel available at the 5-mile and 10-mile points in a half marathon and anticipates arriving at those points in the race at approximately the 40- and 80-minute marks, then experimenting with consuming supplemental fuel approximately every 40 minutes in training would be reasonable as a starting point. Obviously, training or racing that is done in warmer temperatures will result in a greater sweat rate, and fluid replacement may need to be adjusted accordingly (14).

Athletes wishing to improve their performance at a given race distance may find that learning how to execute their ideal race strategy is an important piece of the puzzle. This should start with a review of the previous performance, looking closely at how the athlete’s pace evolved over the course of the distance. Did they fade after the 10-k mark? Did they run an overly conservative pace until the last mile or two and then sprint the final bit?

Most athletes will perform best by striving to maintain a steady and consistent effort through the entire distance. This will result in subtle changes to their pace based on terrain (potentially slightly slower on the uphill but faster on the downhill), wind, temperature/humidity or other conditions. World-class athletes often use this “even effort” strategy to turn in their best performances. A key element of the speed workouts then is to learn exactly what the target race pace feels like so that on race day, this “internal pace awareness” helps the athlete establish the proper pace/effort quickly, making him or her less likely to go out too fast and fade in the second half. For this reason, oftentimes as the race gets closer, hard runs or speed work are almost exclusively race pace segments. Likewise, a key element of hill work is to learn the appropriate effort and strategy to use on different grades. As seen in Table 2, elements of hill work and other forms of speed work are continued throughout the training cycle.

If the athlete lives in the location where he or she will be racing, and he or she is able to run some of his or her training runs on the actual course for the race, he or she will be rewarded with both a reduction in prerace anxiety and a “home course advantage.” Improved understanding of the course profile will enable him or her to capitalize on opportunities during the race that might be overlooked by other athletes less familiar with the course specifics.


The athlete’s accumulated fatigue and fitness both will decay as training is reduced in advance of an event; but they do so at different rates, with fatigue decaying faster than fitness. Indeed, modeling of this concept of reduced training or taper in advance of a key performance to reduce overall fatigue while maintaining fitness has been in the literature for decades (4).

As the date draws near for the target race, it is important for the athlete to maintain some volume of race-specific intensity running while reducing overall training volume to enhance recovery and reduce accumulated fatigue (8,9,15). Fresh legs on race day are a vital part of the equation for a successful race performance. Athletes vary in their taper preferences, with some preferring a longer (14 days) and others a shorter (8 days) period of reduced training volume (15). In this regard, finding what works best may take trial and error over several training cycles, but a generic taper of 10 to 14 days is a reasonable starting point. Most athletes find that reducing total weekly mileage and maintaining training intensity works best. For a 14-day taper, the runner might reduce total mileage by approximately 30% the first week, then reduce it further in the week of the race and potentially include an extra rest day before the race. Table 2 shows a sample training plan with a 14-day taper included.

Psychological preparation and review of specific race strategy should be ongoing during training but may take on more importance as race day nears. Review of course logistics, anticipated weather, as well as specific pacing strategies should be emphasized so that the athlete goes into the event with a clear plan. Most athletes (other than those in the elite corral) find that the first mile of the race is crowded and may find it difficult to settle in to the appropriate pace; however, the crucial mistake to avoid is going out too fast in this first mile. Even elite half marathoners often run the first mile slightly slower than goal race pace. As soon as possible, athletes should get an accurate assessment of pace through mile markers or use of a GPS watch and then make adjustments accordingly. If the athlete has practiced race pace in training, this will help tremendously with pace awareness. As the race unfolds, strategies like clustering (to reduce wind resistance) or running the tangents can improve the eventual outcome.


Ultimately, achieving an improved performance is the culmination of not only optimized training and taper, but also getting lucky with optimum race conditions and selecting a race with a favorable course profile. Monitoring the athlete’s training and race performance and learning what works well for him or her is part of the ongoing process and part of what makes distance racing fun.


The half marathon is one of the most popular road races in the country. Many runners, after completing their first, are interested in improving their finish time. Increasing weekly mileage and long runs form the foundation, with the addition of one to two high-intensity workouts per week as the icing on the cake. Tapering properly and race preparation/execution (e.g., knowing the course, not starting too fast) will give the runner the best chance of running a personal record.


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Half Marathon; Easy Miles; Speed Work; Taper; Improved Performance

© 2018 American College of Sports Medicine.