Will Running Twice a Day Improve Running Performance? A Summary of Research and Perspectives on Multiple Daily-Running Sessions.

uccessful distance runners around the world use the widespread practice of running twice a day. Most elite distance runners train twice a day at least a few days each week. Many elite Kenyan runners, for example, work out two or three times each day from their training base near London. This practice is especially prevalent among marathoners and ultrarunners. But is all this mileage worth it? Or is there a point of diminishing returns where excess running is counterproductive? Let’s have a look at what the coaches, runners, and exercise scientists say about two-a-day workouts.

HISTORY AND GENESIS OF RUNNING TWICE DAILY

Running twice daily became a regular part of elite runners’ schedules since the late 1950s when noted New Zealand coach Arthur Lydiard first boosted his runners’ mileage to around 100 miles per week, using a morning jog for supplementary mileage.

Americans were quick to pick this up. Max Truex employed this type of training and placed sixth in the 1960 Rome Olympic Games 10,000 meters, the highest an American distance runner had performed for decades (Louis Tewanima won the silver medal in the 1912 Stockholm Olympic Games). Then Billy Mills won the gold in this event in the 1964 Tokyo Olympics. It is unknown whether Mills ran twice daily in his conditioning. At about that time, in 1962, Iowa State distance men cut an average of 30 seconds off their distance-event times when they started running twice a day. Since these early times, the practice has become the norm and is considered essential for all elite-level runners.

WHY COACHES RECOMMEND RUNNING TWICE DAILY— PURPORTED BENEFITS

In his book Run to the Top, Arthur Lydiard claims, “Once the hard training has been done—the anaerobic work—any supplementary easy training will improve the runner’s efficiency.” Furthermore, Lydiard claims that the second workout “assists in the recovery from low blood pH that may have developed from anaerobic training.” Thus, a light run the morning after a track workout loosens you up and flushes away some of the legs’ residual waste products before the main run that evening.

Another renowned New Zealand coach, Arch Jelley, whose most successful protégé was former world mile record holder John Walker, claims the advantage of shorter daily runs is that they can be done at a faster pace while maintaining volume.

Bob Wischnia, one-time deputy editor of Runner’s World magazine, wrote in his article “When Once Is Not Enough,” in the October 1981 issue of that magazine, “Physiologically there doesn’t appear to be any marked difference between doing 15 miles in two separate workouts and 15 in one shot. We do know that it’s total volume of work that provides the training stimulus and that it is not dependent on how the work is divided up.”

He continues, “It is generally agreed that for a distance runner to achieve and maintain his full potential, he must build a mileage base. The more miles you run, the stronger you will be. Certainly some runners carry this to the extreme with 150 miles a week or more, but runners who thrive on megamileage are at least theoretically correct in assuming that total work performed—mileage—provides the strongest endurance-training response.”

Skip Brown and John Graham, in their book Target 26—A Practical, Step-ByStep Preparatory Guide to Running the Marathon, pose the question: “Are two short runs as beneficial as one long run of the same distance?” They explain that there have been no conclusive studies to prove that one way or the other is best. “It probably doesn’t make much difference as long as training is not composed entirely of five-mile runs. Long runs are necessary. What really matters is total mileage, and any difference in conditioning that might result from combining smaller runs is probably marginal . . . in terms of race performance.”

Bob Glover and Pete Schuder, in their book The Competitive Runner’s Handbook, recommend against running twice daily unless you are a top-level runner wanting to move up to a more competitive level. They concede that it’s OK to tun twice daily if you have a busy schedule where it’s necessary to break your runs into two-a-days to have time to meet the demands of family and job, or if you want to save time and money by running to and from work.

Glover and Schuder state other reasons why you might want to do twice-daily workouts: for recovery in the days following a hard race (by doing two short

runs), or a morning jog before an interval-training workout to loosen you up, or if you are running high mileage.

Hal Higdon, author of Marathon—The Ultimate Training Guide, points out the social and logistical difficulties associated with running twice daily. “You may be able to work out twice a day if your profession is running, but if you have other interests—a job, a family or other demands or pursuits—trying to cram a second workout into a busy schedule may not be worth it.”

Renowned U.S. exercise physiologist David Costill, Ph.D., writes in his book A Scientific Approach to Distance Running, “It is a fairly common practice for distance runners to train two sessions per day. This method of dividing the total daily training distance into two sessions apparently enables the runner to tolerate a greater volume of running. At present there is no evidence to support or refute this practice.”

Many experts and coaches agree, then, in a vague sort of way, that two-a-day running sessions can help with such things as sore legs, saving money and time commuting, recovering from races, loosening up before an interval workout, achieving higher volume of mileage, or performing the shorter training runs at a faster pace.

Others are more ambivalent about the practice—it really doesn’t matter, they say, whether you split up your daily mileage into two runs or one longer run.

And some coaches claim that running twice daily is not necessary because of the extra time spent dressing and showering and because of undue fatigue.

So the question of whether twice-daily running sessions have an advantage over a single daily training session remains unanswered. Let’s turn to what the research shows.

WHAT RESEARCH SHOWS ABOUT RUNNING TWICE DAILY

Few studies have been done on twice-daily training, for obvious reasons. It’s very difficult to find people who are prepared to run that frequently. The anticipated dropout rate from injury and fatigue further restricts the pool of potential runners who could participate in such a study to already experienced and well-trained runners. And it’s almost impossible to get these runners to change their training schedules to twice daily, unless they are already doing it.

Only five well-designed studies have investigated this question to any depth, plus one obscure study from the former Soviet Union. Information about this early study from the Lenin Institute of Physical Culture in Russia is hard to come by, but it is known that after one month of twice-daily running, athletes could cover a given distance noticeably better than those who trained once daily. In addition, the twicea-day group took from two to five minutes less to recover from a given workload.

The remaining studies were done in the United States, dating from 1968 to 1981, and include two unpublished master’s degree theses, one by this author.

Summary of the major benefits and disadvantages of running twice

daily

Supposed Benefits of Running Twice Daily

Apparent Disadvantages of Running Twice Daily

Loosen up legs before an interval workout.

Help legs recover after a hard race.

Save time and money on commuting.

Enable you to handle higher volume of mileage.

Enable you to do two faster-paced runs daily.

If you have a busy schedule, running shorter runs twice daily may help you

It may have the opposite effect— your legs may be too sore after running twice daily.

It may prevent your legs from recovering after a hard race. It can cause chronic reduction of muscle-glycogen stores.

It may cause increased injury rates.

Motivating yourself to run twice daily may be harder than once daily.

It may cause excessive fatigue because of incomplete recovery between the twice-daily runs.

The extra time taken by dressing and showering is not time efficient.

find more time at home.

Thomas Rogan, in his Ball State University thesis The Values of Supplementing a Daily Training Program for Track Athletes with a Second Training Session of Continuous Running (1968), found no improvements in VO,max or performance times over 800 meters and one mile between groups that trained once and twice per day. In this study, the twice-daily running group ran a supplementary eight kilometers in the mornings.

In 1973, Watt, Buskirk, and Plotnicki, in their published paper A Comparison of Single Vs. Multiple Daily Training Regimens: Some Physiological Considerations, concluded that athletes who have already acquired a high degree of preseason conditioning could follow single daily-training programs as effectively as twice-daily running.

In this study, one group followed a twice-daily running program while a second ran once daily for nine weeks. Their one-mile times were assessed before and after the training period, and all groups improved similarly. This study’s subjects included two groups of trained distance runners and one group of untrained runners.

The rate of improvement in the untrained group was greater than in the two trained groups, as you might expect, because their potential for improvement was greater than the two other groups. All groups experienced significant resting

bradycardia (slower resting heart rate). The researchers concluded that once a high level of conditioning has been attained, there is little difference in performance between athletes who train once and twice daily.

Mostardi, Gandee, and Campbell, in a 1976 study of 16 varsity track men (Multiple Daily Training and Improvement in Aerobic Power), suggested that performances were poorer when the frequency of workouts per day was increased. They attempted to determine the effects of one to three daily training sessions on maximal aerobic power (VO,max) over a four-week training period.

Although VO,max increased significantly for all groups in their study, the greatest increase was attained by the one-per-day training group and the least by the three-per-day group. They also found that one-mile times, although significantly lower for all groups, showed less improvement as the frequency of daily training increased.

They suggest that as daily frequency of training increases, there is a trend toward reduced improvement in VO,max concurrent with lower plasma-glucose levels. Mostardi believes that the constant stress of multiple daily-conditioning sessions leads to reduced carbohydrate stores, and thus to fatigue.

Undeterred by these results, Mostardi and Campbell conducted another study in 1981, Effects of Training Once Vs. Twice Per Day and Improvement in Maximal Aerobic Power, using 13 varsity track men who ran interval-running sessions once or twice daily. After four weeks of training, both groups had an improvement in VO,max, but neither group was significantly better than the other. Submaximal heart rate was significantly lower for both groups.

Again they found blood-glucose levels to be lower in the twice-daily running group compared with the once-daily group. They concluded that training two times per day is not associated with improvements in VO,max over training once per day.

My 1982 master’s thesis, The Influence of Single Vs. Double Aerobic Running Sessions on a Series of Practical Tests in Moderately Trained Subjects, involved three groups of six fit Ohio University students who could run 10K between 33 and 43 minutes or could run 30 to 40 miles per week. They were rigorously tested over 400 meters, one mile, the 12-minute and 30-minute runs for distance, and the standard physiological parameters of body composition, blood pressure, and resting and submaximal heart rate.

Members of the control group (Group 1) ran as they pleased, doing whatever running they felt like. Group 2 ran four miles in one session at a fast pace, five days a week (20 miles per week), and Group 3 ran four miles in two sessions at a slower pace, five days a week (40 miles per week). The training period lasted six weeks.

The results were surprising—there were no significant differences in the results among all three groups despite the large differences in frequency and volume of training. As can be imagined, all three groups ran faster and farther in the

Summary of Research on Running Twice Daily

Study Results/Conclusions

Rogan (1968) No improvements in VO,max or times of twice-a-day runners over single daily runners.

Watt, Buskirk, Plotnicki (1973) Little difference in performance between groups that ran once or twice daily.

Mostardi, Gandee, Campbell (1976) Less improvement in one-mile times and VO,max as frequency of training increased.

Mostardi, Campbell (1981) Training twice per day does not improve VO,max more than training once per day. Blood-glucose levels in twice-a-day runners lower than once-a-day runners.

Stevenson (1982) No significant differences in time trials over 400 meters, one-mile, 12-minute, and 30-minute runs between groups running once or twice daily.

performance posttests, but no single group performed better than any other. This meant that splitting up daily mileage of eight miles into two sessions did not incur any special benefit over completing half that distance at a higher intensity.

Thus there is little, if any, scientific evidence suggesting that multiple daily workouts lead to greater aerobic fitness and performance gains. So we face an apparent paradox where there is little or no direct proof of the value of running twice daily, yet elite runners still run twice a day. And the question remains, do any perceived benefits of double workouts apply to the rest of us (nonelite) runners as well?

DO RUNNERS TRAINING TWICE DAILY EXPERIENCE MORE INJURIES?

To date, there is no research on this aspect of two-a-day running sessions. Experts weigh in on both sides of the debate. Some claim that running twice a day is more likely to cause injuries, and others less. This may be a case of selective choice—runners who get injured (or sick) more often after changing to twice-daily workouts will quickly fall back to running once a day. One physical therapist I interviewed said, “It is likely that runners self-select and that it’s probably very individual to each person.”

WHAT DO THE RUNNERS SAY?

We have seen what the coaches and exercise scientists have to say. Now let’s look at what the runners think. Ed Eyestone in a Runner’s World article says,

“The majority of successful elite runners lace up their running shoes 10 to 12 times a week. Running three to five double workouts per week allows you to log significantly more weekly mileage on a consistent basis, and runners who average higher mileage have been shown to have better running economy than lower-mileage runners. Even when studies match high- and low-mileage groups who have similar VO,max scores, the higher mileage runners score better in economy—meaning less energy to run fast.”

Pete Pfitzinger, exercise physiologist and former elite marathoner, says, “A basic principle is to not do double workouts until you have maximized the amount you can handle in single workouts. Staying with longer single runs builds endurance, while shorter double runs allow you to train at a faster pace. Double runs can also be beneficial in speeding recovery.”

ADVICE FOR RUNNERS CONTEMPLATING RUNNING TWICE DAILY

Before attempting twice-daily workouts, it is wise to maximize the amount you can handle in single daily workouts. The prerequisite for running twice daily is to comfortably handle running sessions of 40 to 60 minutes at least five to six days per week. If you are not ready for that sort of training, you are probably not ready for two-a-days. It will take the beginning runner at least a year or longer to build up to this stage.

However, since most of you reading this are marathoners or ultrarunners, you are probably doing this in your sleep and are more than ready to try twice-daily workouts. Here are some practical guidelines to follow when boosting your mileage by running twice daily.

Should You Run Twice Every Day?

Even seasoned runners limit their total number of workouts to 10 to 12 per week. If you are starting out, running in the morning for 20 to 30 minutes, two to three times a week, is a great start. Run on alternate days. That is, have a once-daily running session, then twice daily the next, then once daily, and so forth. If you handle 20 minutes OK, proceed up to 30 to 35 minutes gradually.

What Pace Should Your Twice-Daily Workouts Be?

Most of your morning running should be slow and easy. You will soon find out why—that will be all you can do! The days when you go for an early-morning session and find your pace rising above a slow jog will be few and far between.

How Can You Expect To Feel When Starting Twice-Daily Running?

You will notice some fatigue during or after the runs. This is normal—you should adapt within three to four weeks if your pace is slow enough and you pay attention to your nutrition.

Sample Training Schedule Introducing Twice-a-Day Running Sessions

Monday Tuesday

Wednesday Thursday Friday

Saturday Sunday

A.M. 20- to 30- 20- to 30- 20- to 30- No Long minute minute minute running run slow jog slow jog slow jog

p.m. Your Your Your Your Your standard standard standard standard standard run run run run run distance distance distance distance distance

Nutritional Considerations for Running Twice a Day

Mostardi and Campbell’s 1981 paper showed evidence of chronic muscle- glycogen depletion. You may have difficulty maintaining an adequate caloric (and carbohydrate) intake to replace your fuels at the rate they are being used. It is common for twice-a-day runners to get a meal behind. This contributes to fatigue and its symptoms, such as crankiness, constant tiredness, and soreness. Once this sets in, it is hard to recover, and you are headed for exhaustion or illness.

Your goal is to refuel and rehydrate before your next workout. There are many ways that you can ensure an adequate caloric intake. Drink lots of cranberry juice, grape juice, or any other fruit juice you enjoy. You will get needed calories and carbohydrates this way, but make sure you drink plenty of water, too.

Your weight may fluctuate widely if you run two workouts a day. This is primarily related to your hydration status. It is important to keep an eye on your weight before and after each workout, especially in hot weather. Weight lost during training represents water lost. For every pound lost during your run, drink 20 to 24 ounces of fluid to ensure rehydration. It is also recommended that you keep your fluid intake up throughout the day and drink an additional 16 to 20 ounces of fluid two hours before doing the second running session of the day.

To replenish your depleted blood-glucose and muscle-glycogen levels and speed recovery, start consuming carbohydrates within 30 minutes of finishing exercise. A recommended guideline is to ingest 1 to 2 grams of carbohydrates per kilogram of body weight after your run and again two hours later.

You will need to plan your carbohydrate foodstuffs ahead, or you will find yourself eating less-desirable food low in nutrients such as doughnuts, candy, cookies, hot dogs, hamburgers, and chips. These are poor choices for replenishing your glycogen stores.

Fat is very slow to be digested and absorbed and slows the absorption of everything else in the stomach. It is best to choose low-fat, nutrient-dense carbohydrate foods. Recent studies show that carbohydrate and protein consumed

together postexercise may help replenish muscle-glycogen stores and contribute to earlier repairs of muscle tissue.

If your stomach is churned up by your morning runs, try fruit smoothies, fruit yogurt, bagels, or liquid recovery drinks such as Instant Breakfast, Boost, or any of the many others on the drugstore shelves that are high in carbohydrates. It is important that you also include some protein in your meals to help muscle repair and growth.

“Tt’s important to realize that nutrition is part of your training, not something that is adjunct to it,” says registered dietitian Sally Hara, M.S., a board-certified specialist in sports dietetics. She emphasizes, “For endurance athletes, carbohydrates are key. They are the preferred food for exercise and ultimately what is going to prevent you from ‘bonking.’”

Hara, director of ProActive Nutrition in Kirkland, Washington, adds, “The focus for marathoners and ultrarunners is fourfold. First, maximize glycogen stores. Second, fuel prior to exercise. Having a high-carb snack or meal a couple of hours prior to running gets fuel in the tank ready to feed the muscles. Third, fuel during exercise. For runs lasting longer than 60 minutes, athletes should consume 30 to 60 grams of carbohydrate per hour. Use sports drinks and/or sports gels. And fourth, refuel and rehydrate postexercise.”