Running, health and well-being

Many people start, and continue running for health reasons. This chapter aims to describe some of the health benefits of running, as well as discuss some of the basic strategies to employ during running that may support and improve healthy running. From breathing and pacing, to running form and nutrition, these basic strategies can help individuals stay healthy while starting (and maintaining) a running regiment.

Physical benefits

A regular program of physical activity has been shown to provide a multitude of physiological benefits, including reduced risk of all-cause mortality, cardiovascular disease, some types of cancer, and diabetes, improved blood pressure and cholesterol levels, body composition and body weight, joint and bone health and musculo-skeletal fitness (Kramer, 2019). For another free, Creative Commons resource covering the general benefits of physical activity, see  https://open.lib.umn.edu/physicalactivity/chapter/2-2-physiological-benefits/.

Running can be categorizes as primarily an aerobic activity, meaning it requires oxygen. Aerobic exercise is also sometimes referred to as cardiorespiratory endurance exercise. These types of activities, like swimming, biking, walking, and any other activities that involve continuous, repetitive contractions of many of the body’s major muscle groups, cause an increase in heart rate (that’s the cardio part!) and breathing rate (that’s the respiratory part!) for an extended duration. The minimum amount of time required for an activity to be defined as aerobic exercise is usually defined as at least 10 minutes continuously, though shorter bouts may still be beneficial, especially for those individuals just starting an exercise program or are otherwise in a deconditioned state (American College of Sports Medicine et al., 2018). A body of research has recently emerged demonstrating positive aerobic adaptations from high intensity, short duration interval training as well, which will be discussed further in Chapter 2.

The elevation in heart rate occurs to meet the body’s need for oxygen, which is carried through the bloodstream to the working muscles, where it can be used to convert carbohydrates and fats to the energy source used for muscular contraction: adenosine triphosphate, or ATP. Aerobic exercise is the best way to improve or maintain cardiorespiratory fitness, which has been identified as a key health-related fitness variable (American College of Sports Medicine et al., 2018).

Running is not only aerobic exercise, it is by definition vigorous exercise, as opposed to walking, which is considered moderate exercise (American College of Sports Medicine et al., 2018). While there are still benefits to moderate exercise, the health benefits of vigorous exercise are greater and/or can be achieved in less time. Vigorous intensity aerobic exercise, when compared with moderate intensity, reduces cardiovascular disease risk and diastolic blood pressure, and improves glucose control and aerobic capacity (Swain & Franklin, 2006). Furthermore, even among runners, a greater intensity of exercise is associated with improved health outcomes. A study of over 50,000 runners in the United States found that higher usual running speeds are associated with lower prevalence of hypertension, hypercholesterolemia, and diabetes (Williams, 2008).

Unlike some aerobic exercise, such as swimming and biking, running is a weight-bearing activity. While this may increase the risk for certain types of injuries (see Chapter 7), it also provides important health benefits. Running can help improve bone density by stimulating bone remolding (Williams  Judith et al., 1984). Increased bone mineral density helps protect against fractures and frailty, which can occur later in life as a result of osteoporosis.

Some of the physical benefits of exercise are due to changes in our endocrine and paracrine systems. The endocrine system works by releasing hormones in one location of the body, into the bloodstream, so that they can act on other parts of the body. The paracrine system involves release of signaling molecules that act more locally in the body. Exercise turns on all sorts of endocrine and paracrine responses that, together, can improve long-term health.

One prime illustration of how exercise can improve health involves the stress hormones, epinephrine and norepinephrine. When we exercise, a cascade of these hormones is released from the adrenal glands, located on top of our kidneys. They facilitate increased heart rate, blood pressure, blood flow, and breakdown of carbohydrate and fat for use during exercise (Wilmore et al., 2004). This acute increase in stress hormones helps us to exercise more effectively, but the real health benefit comes after we stop. When people say they are feeling stressed or under stress, they are referring to that chronic, all day long feeling of being ill at ease and under pressure. It turns out these same stress hormones that help us exercise can be chronically elevated due to lifestyle pressures. Running regularly can lead to lower levels of these stress hormones (Nabkasorn et al., 2005). That means lower heart rate, blood pressure, and well, lower stress. Thus, the physical benefits also have important implications for our mental, emotional, and cognitive well-being.

Mental benefits

A vast body of literature has illustrated the mental benefits of regular exercise, including reduced anxiety, stress, and depression, and improved mood state (Mikkelsen et al., 2017). For a summary of the cognitive and psychological benefits of exercise, see https://open.lib.umn.edu/physicalactivity/chapter/2-3-cognitive-benefits/ and https://open.lib.umn.edu/physicalactivity/chapter/2-4-psychological-benefits/ (Kramer, 2019). The cognitive benefits include improved academic performance and brain function, and reduced risk of age-related cognitive impairment and disease, while the psychological benefits include enhanced mood, reduced stress, anxiety, and depression, and improved self-esteem and body image (Kramer, 2019).

Running, as a form of vigorous, aerobic exercise, can improve mental health, mood state, and cognitive function. Many of us have experienced the mood-boosting, brain-clearing effects of a good run. Some fall under the camp of feeling great during the run itself (the so-called runner’s high), while others would be more likely to say that it feels really good to stop! Either way, a growing body of evidence supports the mental benefits of running.

Depression and anxiety are being reported at alarming rates in the United States, with anxiety affecting nearly 1 in 5, and a major depressive episode within the last year in nearly 7% of the population (Anxiety and Depression Association of America, n.d.). Fortunately, exercise in general and running in particular can help.

The effect of an exercise program is on par with the standard of care, which is psychotherapy and or anti-depressant drugs, and may actually provided augmented benefits when used in combination with these other treatments (Kvam et al., 2016). One study of young women with mild-to-moderate depressive symptoms found improvements in symptoms after an 8-week running program (Nabkasorn et al., 2005), and similar improvements have been noted in other populations (Greist et al., 1978). A small reduction in symptoms of anxiety can be seen after just a single bout of exercise (Ensari et al., 2015), with larger differences seen in individuals who are following a regular running program (Dyer & Crouch, 1987).

Anecdotally, many runners talk about how getting out for a few miles improves their mood, and just makes them feel better for the day. Research backs up the idea that both beginning and advanced runners have improved mood state compared to non-runners (Dyer & Crouch, 1987).

In a population of youth and adults with mood disorders, participating in a structured group running program improved working memory and cognitive processing speed (Keating et al., 2019). For the general population, there is evidence of improved cognitive function as well. For example, runners scored lower on a confusion scale than non-runners (Dyer & Crouch, 1987), and cognitive task performance improves after aerobic exercise, including running and cycling (Lambourne & Tomporowski, 2010). It is important to note that those dealing with mental health issues should not rely solely upon exercise, but rather should use it as one of many available tools. For those who are otherwise in good mental health, it’s important to pay attention to how much running is optimal for positive effects on mood and energy, knowing that more is not necessarily better.

Breathing and pacing

For new runners, breathing and pacing are two critical skills to develop. Even for those who have run before, but have taken some time away, consciously focusing on these two skills can aid in a smooth return to running. It may seem like a bit of a stretch to you to characterize these two concepts – breathing in particular – as skills, but focusing on these two simple things can make all the difference between a successful start of a running program and a frustrating, exhausting pattern of over-extending yourself and having to start from scratch.

Breathing

Breathing can fundamentally be characterized as an autonomic process of the body. In other words, we do it whether we think about it or not. That’s why we continue to breathe while we’re asleep, rather than asphyxiating. That’s all well and good when we’re not doing anything strenuous, but when we begin to exert ourselves, our breathing increases in two important ways: both in how frequently we are breathing in and out (known as respiratory rate) and the depth of each breath (known as tidal volume).

These increases in respiratory rate and tidal volume occur to meet the increased energy demand that our body requires. Specifically, in order to produce a steady supply ATP (energy) in our working muscles, we need to deliver oxygen to those muscles. Endurance training improves our cardiac output (how much blood our heart can pump), the system of capillaries in our muscles to get that oxygen-rich blood where it needs to go, and increases the numbers of enzymes and mitochondria in those working muscles cells, to better utilize the oxygen that is delivered (McArdle, 2015).

But it all starts with our breathing. Contrary to common belief, our lungs do not expand due to training, but endurance training can strengthen the ventilatory muscles (McArdle, 2015). In addition, endurance trained individuals exhibit better diffusion capacity (Groves et al., 2016), meaning they are more effective in exchanging gas between the blood and the lungs. This can be explained in part by changes to the pulmonary vasculature, which facilitate increased blood flow to and from the lungs (Lalande et al., 2012). So while our lungs don’t expand, their functionality improves. Aerobically trained individuals, like runners, are better able to bring oxygen into the blood stream, and getting carbon dioxide out of the body.

During exercise, there is a natural shift from breathing through the nose to breathing through the mouth, which is wider and accommodates greater airflow. While some have advocated for nasal breathing, and evidence exists of a greater efficiency with nasal breathing at submaximal intensities, runners generally feel the need to switch to oral breathing at high intensities (LaComb et al., 2017). Combined oral and nasal breathing patterns can be used based on individual preference and exercise intensity.

Human beings have greater flexibility in how their breathing patterns interact with their stride pattern than mammals who run on four legs, who are forced by the mechanics of their body to breathe in a 1:1 ratio with their stride (one breathing cycle per one gait cycle) (Bramble & Carrier, 1983). This coordinated breathing and stride pattern is known as entrainment. Untrained runners do not exhibit entrainment, whereas experience runners do (Bramble & Carrier, 1983). However, unlike our 4-legged friends, humans retain a greater flexibility of breathing pattern, which allows us to adjust our ratio of breathing cycles to stride cycles based on the intensity of exercise.  Exercise intensity drives how much oxygen we are using and how much carbon dioxide we are producing, and thus how fast and how deep we need to breathe in order to exchange those gasses.

Breathing in rhythm with our stride pattern appears to be more efficient, resulting in a lower oxygen cost of exercise (Bernasconi, 1993). So when you set out to run, there can be a benefit to consciously practicing a regular breathing rhythm that is synchronized with your stride pattern. There are a number of patterns that commonly have been observed in runners, with stride-to-breath ratios of 2:1, 3:1 4:1, and 5:2 (Bernasconi, 1993). Experienced runners often start at a 4:1 and shift to 2:1. Note that the stride cycle is defined as both a right and left step, So, the common 2:1 ratio indicates one breath every four steps, typically performed with an inhalation for 2 steps and an exhalation for 2 steps. For a beginner, this rhythm is a good place to start. It also will likely land you in at a respiratory rate of about 45, assuming your running cadence (or step rate), is in the ideal range (see below in the section on running form).

If it feels too fast, shifting to a 3:1 or even 4:1 rhythm makes sense (inhale for 3 or 4 steps, respectively, and exhale for a matched number of steps). On the other hand, if you find yourself feeling out of breath with the 2 step inhale, 2 step exhale rhythm, you have a couple of options. You can shift to a 2 step inhale, 1 step exhale. This commonly occurs during high intensity running, when an individual is running a pace that cannot be sustained for very long. The other, more sustainable, option is to consciously slow your pace in order to find a more comfortable pace.

Many new runners find themselves rapidly shifting to shallow, quick breathing patterns because they fail to adequately expand their lungs with each breathe. Focusing on diaphragmatic (or belly) breathing, rather than chest breathing, can help to more fully expand the lungs (How to Breathe While Running, n.d.). Practicing belly breathing at rest by focusing on fully expanding the abdomen as you inhale can help you learn how that feels. Then you can work on putting it into practice while running.

Pacing

Pacing during distance running is likewise a skill that requires conscious practice to develop. For an illustration of this, head down to your local kid’s fun run type of event, and you will see most of the kids sprinting off the starting line, and gradually slowing, perhaps stopping and walking intermittently, and then sprinting again when the finish line comes into view. While the degree of slowing may not be as drastic, the same patterns often occur in recreational adult runners.

There are many tools available to allow you to monitor pace. Running on a track, for example allows frequent feedback on your pace, if you check your lap times (“splits”) each lap. You need a stopwatch of some sort in order to accomplish this. Treadmill running, on the other hand, requires you to physically adjust the pace if you want to go faster or slower, so you are always aware of your running speed. However, the skill of good pacing cannot be fully developed on a treadmill, because it does not require you to consciously focus on running a steady tempo. Rather, you either run the speed that the belt is moving or you will fall off the back! The use of global positioning system (GPS) watches has become increasingly popular (see Chapter 5). These watches provide a reasonably reliable measure of your running speed during outdoor running.

Tools like a GPS watch can provide a very detailed picture of your pace throughout the run, as well as linking to apps and other tools to analyze pace under different conditions and circumstances, such as running uphill versus on flat ground. Using such a tool can help you grow in self-awareness of how you are pacing yourself during runs appropriately in order to accomplish the goal for the day.

Many beginning runners struggle with starting out too fast on their runs, and then being forced to slow or even stop and walk to recover. While there’s certainly no shame in this, it is frankly not a very pleasant or enjoyable experience. Starting out at a slower pace, and actually finishing a little faster than you started creates a positive feedback loop of successfully executing a run, and finishing with a feeling of accomplishment. There are performance benefits as well, as faster runners tend to run a more even pace in races such as a marathon (March  Daniel et al., 2011).

On the other hand, as you become more fit, you may find that the pace you are accustomed to starting out at is too slow to provide any challenge, so you can adjust according to feel. In general, keeping a relatively consistent pace throughout the run is optimal, though you should allow yourself a few minutes at the beginning to run more slowly as your body gets warmed up. See Chapter 4 for more details on structuring different kinds of workouts.

Running form

Chances are, if you have recently started running, the following thought has popped into your head: Am I doing this right?

The short answer is that yes, you are doing it right, because you are out there and running, and your body will find the most efficient way to move through repeated practice. The longer answer is that while there is no “right way” to run, there are indeed certain things you can think about and focus on to speed the process of moving you toward your most efficient running stride.

First of all, it is important to acknowledge that every person is unique, with a set of biomechanical, physiological, psychological, and experiential characteristics that belong only to that particular individual. There are certainly limits to how much we can consciously alter our running form in some regards, so it can be counter-productive to talk about “ideal” running form.  However, there are definitely things that we can do to positively impact our running technique. The goal of these practices is to reduce wasted movements, and therefore move in a more energy-efficient manner. Specifically, in this section, we will address the following aspects of running form:

• Footstrike
• Leg and hip mechanics
• Upper body movement

Footstrike

One of the pioneers of the running boom in the 1970s, Dr. George Sheehan, pioneered the “feet-up” approach to running injuries. Sheehan was an author of numerous books on running, and also wrote for Runner’s World magazine. He advanced the idea that running mechanics can be traced from footstrike up through the rest of the body (Sheehan, 1978). In other words, how you land determines the distribution of forces throughout your body. This makes sense when we think of the fact that the foot is the only point of contact the body has with the ground during running – it is responsible for translating forces produced in our body into the ground to propel us forward, and an when we land, it begins the kinetic chain of the absorption of those forces.

The normal pattern that occurs in most people is a landing that starts on the outside (lateral) part of the foot, often but not always with the heel landing first. This position of the foot is called supination. As the runner lands, the foot rolls inward, with the arch of the foot slightly flattening and stretching. This movement is called pronation, and is part of how the body distributes and absorbs the forces of landing that occur with each step. As the runner prepares to push off again and the foot prepares to leave the ground, the tissue of the arch rebounds and the foot supinates again, returning ideally to a neutral position where the runner can push off through the toes.

If you have heard of pronation at all, it was probably in a negative context. Indeed, excessive pronation (or overpronation) is quite common in runners, and has often been characterized as a risk factor for injury (Fletcher, 2017). See this video for a good illustration of what overpronation looks like:

https://www.youtube.com/watch?time_continue=4&v=hzM0-9vILcA&feature=emb_logo.

While overpronation is problematic, a moderate amount of pronation is important in absorbing the forces that we experience upon landing. In fact, there are some running injuries associated with inadequate pronation (or sometimes called oversupination). This can be caused by a foot that is too rigid, and does not flex to absorb those landing forces. We will explore the ways that proper footwear can help address either of these problems in Chapter 5, and examine the specific injuries associated with overpronation and oversupination in Chapter 7.

Another aspect of footstrike is landing location. There has been much debate in recent years about rearfoot footstrike, versus a midfoot or forefoot landing pattern, with some arguing that modern, over-built running shoes are to be blamed for the prevalence of rear-foot striking (Lieberman et al., 2010). The vast majority of runners in the middle of a long distance races exhibit a rear-foot striking pattern, though the prevalence of mid- and fore-foot striking is higher in faster runners (Hasegawa  Hiroshi et al., 2007; Larson et al., 2011). The landing location of the foot may influence the types of injuries that a runner is at risk of developing, as rearfoot striking puts greater stress on the knee, whereas forefoot striking places greater stress on the ankle and Achilles tendon (Kulmala et al., 2013).

While there are some who will argue vehemently about what part of the foot should land first, there is more widespread agreement on where the foot should land, in relation to the body’s center of mass. The foot should land close to directly under the hips, rather than far out in front. The hips correspond approximately with the body’s center of mass, such that landing close to this position will reduce deceleration on landing and essentially allow the runner to fall forward with each stride (Romanov & Fletcher, 2007).

This runs contrary to the advice sometimes given by coaches and others to “stretch your stride out.” Consciously lengthening one’s stride is likely to lead to “over-striding,” which is landing with your foot extended out in front of your center of mass. This leads to more time spent on the ground with each step, and higher braking forces with landing (Romanov & Fletcher, 2007). Many critics of heel-striking emphasize these stride qualities as serious negative consequences of that type of landing. Indeed, if you put your foot far out in front of you, you will be hitting the brakes, and slowing your forward momentum until you can once more push off. This repeated braking and acceleration will cost you a lot of energy, and these high impact forces could also cause injury. However, dramatically shifting to a forefoot strike could lead to other injuries, due to the greater stress on the calf muscles and achilles tendon. A safe middle ground is to focus on landing directly under the center of mass, regardless of which part of the foot touches the ground first.

Leg and hip mechanics

The two factors that determine an individual’s running speed are stride frequency and stride length. Stride frequency, also sometimes called cadence, is the number of strides taken per minute. Any runner can easily calculate his or her stride frequency using a stopwatch or phone, counting the number of times one foot hits the ground over the course of that minute. Multiply that number by two to capture the steps taken by the other foot. While there is some variability between individuals, a step rate of roughly 180 per minute is typical of elite runners, and has been commonly recommended for runners (Daniels, 2013).

A slower stride rate is typically associated with overstriding and heavy rear-foot striking. In a study of high school cross country runners, those with the lowest step rates had a higher incidence of injury (Luedke  Lace et al., 2016). As noted above, consciously attempting to lengthen one’s stride is generally counterproductive, due to the likely decrease in stride frequency that occurs. It may also increase risk of injury, as a shorter stride reduces the impact forces of landing (Edwards  W. et al., 2009).

It is, however, important to note that stride length does play a role in determining running speed in the sense that the more ground you cover with each stride, the faster you will be running, if there is no change in stride rate. There are ways to increase stride length without compromising stride frequency. More powerful and coordinated muscular contractions translate into longer strides. A beginning runner will naturally gain strength in the primary muscles used for running, and will also become more coordinated in movements, as the skill of running improves.

Martin & Coe (1997) defined five observable characteristics of highly skilled runners:

• Improved balance and coordination, resulting in less postural work
• Elimination of unnecessary movements
• Refinement and optimization of necessary movements, minimizing loss of kinetic energy
• More effective, efficient use of muscles
• Continually controlled movements replaced by ballistic strokes

Many of these characteristics are inter-related, and together they support the idea that running is a neuro-motor skill, and that when we practice a skill we become more effective and efficient in executing the skill. This may be due to a range of factors, including improved neuro-motor firing patterns and better coordination of the muscular contraction patterns, where the agonist muscles, antagonist muscles, and synergistic muscles work together in a more coordinated manner (Martin & Coe, 1997). The room for improvements in the skill of executing a single step many seem trivial. However, when you multiply those small gains by 180 steps per minute, over the course of a run that may last 20-30 minutes or longer, the improvements reaped by even a small adjustment or improvement in running form can be extraordinary.

Ultimately, developing one’s running stride to embody point #5 is the goal. Rather than having to carefully control movements (i.e., to have to think about running properly), the runner’s body smoothly and apparently effortlessly glides forward, limbs swinging easily liked pendulums, powered by short, efficient, and powerful muscular contractions.

IMAGE: Elite runner

Important visuals to consider regarding running form:

http://www.ahealthblog.com/shorter-warm-up-results-in-significantly-less-muscle-fatigue.html

http://www.runnersworld.com/the-starting-line/proper-running-form

http://www.chirunning.com/blog/entry/10-components-of-good-running-form

http://rapidrunningtips.com/wp-content/uploads/2014/10/4-Steps-to-Better-Running.jpg

Upper body movement

While the lower body is responsible for the job of putting force into the ground to propel the runner forward, the upper body plays an important role in supporting the lower body. As a simple illustration of the importance of the upper body, try running a few strides without using your arms, but rather keeping them straight at your sides. You will notice your torso rotating with each stride, rather than staying relatively stable. The role of the arms is to function as counter-weights to your legs, opposing the angular momentum produced by the lower body (Pontzer et al., 2009). As the left knee drives forward, the right arm follows, moving forward as well. This ensures that the center of mass stays relatively close to the centerline of the body.

The arm actions should follow the leg movements in order to provide this counter-balancing force. However, it can sometimes be useful to focus on the arm action in order to elicit a shift in the lower body movements. For example, during sprinting, the knees should be lifted higher to create greater range of motion through the hips, and thus, a more powerful stride. The arms, then, must also move through a greater range of motion, and move more vigorously. Typically, a sprinter’s hands will come up near shoulder-height at the peak of the forward movement. Coaches and runners may sometimes focus on that more vigorous arm action, and getting the hands into the proper positions in order to provide the proper counter-balance to what the legs should be doing.

Image: Sprinter (https://unsplash.com/photos/3R4vPrSB1c4)

During distance running activities, performed at relatively lower intensities, the arm movements will be less vigorous. In fact, they need to be in order to reduce the energy cost of moving. Imagine trying to run for 20-30 minutes with the vigorous arm pumping action of a sprinter. Not only would it be counter-productive (because it is not matching what your legs are doing), it would be exhausting as well, due to the powerful muscular contractions that are required. During uphill running, where more knee lift is required, arm action should also become somewhat more pronounced, with the hands coming slightly higher.

Proper arm position and action are shown below. Here are some key points to focus on with upper body positions and movements:

• Arms should swing comfortably forward and back,
• Hands should not cross the midline of the body, but may come directly in front of the heart
• Overall, focus on relaxed, smooth, and natural movements
• Eyes should be focused ahead
• Head should be held in neutral position, not tilted to the side, forward or back
• Head, neck, and face should never be tensed
• Shoulders should be loose and relaxed
• Elbows should be at roughly a 90 degree angle
• Wrists should be loose, with fingers slightly bent
• Hands should brush past hips on the backswing

PHOTO/FIGURE: good running form

In summary, overall good posture is similar in running as in daily life. Remember that running is a motor (movement) skill, meaning that each movement we make is a product of the functioning of the neuromuscular system. The brain sends signals through the nerves to stimulate muscular contraction, and peripheral parts of our body send feedback to the brain. Proper running technique can be established through repetitive practice of correct motor patterns. Some improvements may be made just through repetition. However, one can more effectively improve a skill through deliberate practice: that is, practicing in a self-reflective, self-aware manner (Ericsson et al., 1993). Additionally, there are running form drills (discussed in Chapter 4), that can help activate muscles and improve form.

We will discuss more about the mental skills involved with running in Chapter 6, but working on running form requires that the runner pay attention to what he or she is doing (i.e. use deliberate practice). Use your conscious brain to tune in to your body: where are your hands, arms, shoulders, head, neck? Tuning in to these movement patterns can gradually alter your default running form to a more efficient iteration. Remember that good habits take time to be established, and bad habits take time to be eradicated.

Nutrition for running

What follows below is a very brief overview of nutrition and related issues that may be helpful for runners, but is by no means a comprehensive discussion of nutrition, Before proceeding, it may be helpful for the reader to review the following text on nutrition for physical activity: https://open.lib.umn.edu/physicalactivity/chapter/3-5-nutrition-for-physical-activity/ (Kramer, 2019). In addition to balanced, sound nutritional practices on a daily basis, we will look at a few considerations for before, during and after your run, particularly with respect to fueling and hydration.

Pre-run nutrition

Running requires energy, so it is important to start out your run in a well-fueled state. This does not necessarily mean that you need to eat immediately before running. In fact, food that you eat immediately before running is unlikely to be digested and available as fuel yet (with the exception of simple sugars). All that undigested food can cause problems, so runners are often advised to wait 3-4 hours before running after eating a large meal, or 1-2 hours after a small meal or snack (Paul, 2020a).

Rather, being well-fueled means having an adequate supply of energy that is ready to be utilized for exercise. Our two primary sources of energy for prolonged exercise, like running, are glycogen and fat. The body’s preferred fuel source is glycogen, which is stored in the muscle itself. Glycogen is stored carbohydrate that can be easily broken down aerobically (with oxygen) to deliver energy for muscular contraction. Glycogen delivers the most energy for muscular contraction per unit of oxygen consumed. Fat, which can be used for aerobic exercise, requires a bit more oxygen, so it is a less efficient as an energy source. However, even a very lean individual has far more fat stores available to be utilized, compared to glycogen stores, so fat is an important fuel source for very long exercise bouts, or in the event that glycogen stores become depleted. This typically does not occur in runs until 60-90 minutes into steady state exercise (Wilson, 2020).

For exercise that lasts longer than 90 minutes, utilizing fat for exercise becomes more important. But for the average beginning runner, going out for 20-30 or even 40 minutes, the primary source of energy will be stored carbohydrate. If you are running in the morning, unless you are on a low carbohydrate diet, there will be plenty of stored glycogen in your muscles to fuel your workout. However, we also store a small amount of glycogen in the liver, which helps maintain normal blood sugar levels. This glycogen is used slowly during a period of fasting (such as when you are asleep). For this reason, it is beneficial to consume a small, high carbohydrate snack or breakfast prior to running in the morning, particularly if you intend to exercise for a longer duration (Burke et al., 2004).

The timing and composition of a pre-run snack or meal is highly personal, and can be developed through a trial-and-error process. The goal is to be optimally fueled, without experiencing any gastro-intestinal (GI) distress. Some individuals can eat just before running without any symptoms of GI distress, while others need 2-3 hours (or even longer) to digest prior to running.

As a general rule, the smaller and simpler the snack or meal, the easier it is to digest. Additionally, fats and proteins take longer to break down than carbohydrates. Eating a 200-400 kcal snack, comprised predominantly of carbohydrates, is a sound practice to “top off” one’s energy stores. Start experimenting with doing this 1-2 hours before your run, and adjust accordingly, depending on how you feel (Paul, 2020b).

Many runners (71% in one study) do experience GI symptoms such as nausea, bloating, cramping, or urgency (needing to stop and go to the bathroom during the run) (Peters et al., 1999). If you have GI symptoms during the run, you may need to pay particular attention to the composition of that pre-run snack or meal, or even adjust the foods you eat in the day prior to a run. Some common problem foods that can contribute to GI distress in runners are lactose (found in dairy products), high fiber foods, and spicy foods. Ongoing problems may warrant investigation of food allergies and sensitivities to determine the problem foods. Just like the timing of pre-run meals, the composition should be personalized based on what an individual enjoys and tolerates.

Another important consideration for runners is hydration level. Runners should aim to start their run in a fully hydrated state. Running performance can begin to suffer with as little as 2% dehydration (as a percentage of your body weight) (Sawka et al., 2007). This can occur while running, particularly in hot weather. Even in cooler weather, it is possible to become dehydrated. We lose body water in the form of sweat during exercise, but also through respiration. Sweat rates differ between individuals and are influenced by a variety of factors, including weather conditions, clothing, exercise intensity and duration (Sawka et al., 2007).

In order to stay well-hydrated, runners should be sipping water throughout the day. Frequency of urination and urine color can be monitored to assess hydration status. While neither of these is a perfect measure of hydration status, relatively frequent urination, and a clear or very pale urine color indicates that you are well-hydrated, whereas infrequent and/or more deep yellow urine suggest dehydration. Note that caffeine will increase urine output, and can contribute to dehydration. Further, urine color can be affected by diet, the most common example being a bright yellow color following consumption of a vitamin supplement.

During-run nutrition

In most cases, it is not necessary to ingest any fuel during runs that are less than an hour in duration. However, runners may potentially benefit from taking in some calories and fluids during runs lasting over an hour, and are likely to get a benefit in runs lasting around 2 hours and longer (Wilson  Patrick, 2016).

It is beyond the scope of this text to address in any detail the composition of what should be consumed during these longer runs, but in brief, carbohydrates are the fastest to be digested, and are thus the best source of energy during a run. Individual preference and tolerance must be taken into consideration. Sports drinks, such as Gatorade, are composed of simple carbohydrates in a concentration that can be easily absorbed, while providing the added benefit of provided water and electrolytes such as sodium and potassium, which also are lost during exercise. An ideal sports drink solution should contain a roughly 5-8% carbohydrate solution in order to balance fluid needs and caloric needs (McArdle, 2015).

There may be some potential benefits to drinking fluids during runs of 1-2 hours, and clear benefits for runs over 2 hours, but the benefits must be balanced with the increased incidence of GI distress (Wilson, 2020). Sweat rate, as noted below, is influenced by the duration and intensity of exercise. Working at a higher intensity will cause you to sweat more profusely. This is why we can go for a leisurely walk without breaking a sweat on a mild day, whereas a run will cause us to sweat. For most runs under an hour, it is not necessary to drink during the run. However, very hot days or higher intensity workouts may be an exception to that rule.

The International Marathon Medical Directors’ Association suggests that runners drink ad libitum (according to thirst), rather than following a stringent guideline of how much to drink (Hew-Butler  Tamara et al., 2006). Dehydration signals the release of hormones in our body that stimulate thirst. Thus, their sound advice: drink if you are thirsty. This guidance has the further benefit of reducing the danger of hyponatremia (overhydration), a potentially deadly condition that can occur when runners drink excessive amounts over a prolonged period during exercise. Also, drinking according to thirst reduces the likelihood of experiencing those pesky symptoms of GI distress (Wilson, 2020).

Post-run nutrition

After finishing a run, some people feel famished, while others may find it difficult to eat. In either case, it is important to begin re-fueling shortly after finishing a run. The goals of post-workout refueling are 1) to replenish glycogen stores burned during exercise; 2) to ensure sufficient amino acids (the component parts of protein) in the bloodstream to repair damage to muscle tissue, and 3) to return to a fully hydrated state. Incorporating carbohydrate, protein, and fluid into a post-workout snack has thus become a common practice, and has been studied extensively.

Muscle cells are better able to transport glucose into the cell during exercise, and that remains true for a short duration after the end of a workout (McArdle, 2015). A common recommendation is that individuals should eat within 30 minutes of finishing a workout in order to replenish glycogen stores in our muscle cells. While this is not a bad practice, the 30 minute window is not a hard and fast rule. Rather, the importance of eating relatively soon after completing a workout probably depends on a number of factors including: fueling status at the start of the workout, duration, intensity, and training status, as well as how long you intend to go before completing another workout. In short, the more depleted you get during exercise, and the less recovery you will have before your next bout of exercise, the more important it is to begin refueling as soon as possible.

The benefits of rapid re-fueling can be both acute and chronic. For example, one study showed improved glucose uptake and protein synthesis after a 60 minute exercise session when comparing groups that ingested the same beverage either immediately after exercise versus waiting 3 hours (Levenhagen et al., 2001). Another study that involved biking for 60 minutes, 5 days per week, for 4.5 weeks demonstrated better aerobic and body composition adaptations to the training program for the group ingesting a carbohydrate-protein beverage, compared to a carbohydrate only or placebo group (Ferguson-Stegall et al., 2011). The carbohydrate-protein beverage in this study was chocolate milk, which contains a 3:1 carbohydrate to protein ratio. In other words, you do not need to purchase an expensive supplement to reap these benefits. A relatively inexpensive, readily available option like chocolate milk can be quite effective.

Rehydration after exercise can typically be achieved through consumption of water and normal meals and snacks. However, in cases where substantial dehydration has occurred or another exercise bout is expected within a few hours, drinking about 24 ounces of fluid for every pound of body weight lost is recommended (NSCA, 2016).

While it beyond the scope of this text to make general nutrition recommendations for daily living, ample evidence exists to state that one can enhance many measures of health by consuming a diet consisting primarily of whole, unrefined foods, including plenty of vegetables, fruit, fiber, and vegetable proteins while limiting consumption of red meat, trans fats, and alcohol (McCullough et al., 2002).

Generally, nutritional needs in most cases can be met through a balanced diet. It is worth noting, however, that consultation with a registered dietician may be helpful when starting or altering an exercise regiment. Specific to running, one nutritional consideration that is particularly of concern for female runners is iron levels. Over 50% of female runners have been found to be iron deficient, with greater incidence among those who run more (Pate et al., 1993). Iron forms hemoglobin and myoglobin, which are critical in transporting oxygen to the working muscles. Thus, deficiency can lead to impaired performance and excessive fatigue. Consulting with a medical professional and at least annually is always a good idea. Doing so prior to starting a physical activity program can help identify and hopefully avoid the exacerbation of any health concerns.

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