What Happens When You Start Running: From Body Transformation to the Perfect Shoe

Whether you’re a seasoned runner or lacing up for the first time, have you considered the profound effects each step has on your body and health? Go the distance in understanding the transformative world of running.

What’s in this article:

How Running Changes Your Body

Running is an aerobic exercise that can bring about numerous physical and physiological changes. As you run consistently, your cardiovascular endurance improves, leading to enhanced oxygen and nutrient supply to various body parts, including muscles and the brain.1 Over time, this increased efficiency helps reduce the resting heart rate and strengthens the heart muscles. On the musculoskeletal front, running enhances bone density, especially in weight-bearing bones like the femur and tibia, thus reducing the risk of osteoporosis2.

On a more visible scale, running can lead to fat loss, especially when combined with a balanced diet. This not only gives a leaner appearance but also contributes to better metabolic health, reducing risks associated with obesity and diabetes.3 After spending time running you’ll have more energy throughout the day, better posture and your dedication may even lead you to a better diet to maximize your efforts and reap their rewards. An added bonus, thanks to the “afterburn effect”, your body continues to torch calories even after you’ve finished running, leading to a noticeable decrease in body fat percentage. Stick around, we’ll dive deeper into this awesome phenomenon soon.

When Running, Which Muscles Are Used?

The act of running engages multiple muscle groups throughout the body. Primary movers include the quadriceps, hamstrings, calves, and glutes, which provide the power for propulsion and support body weight. But running isn’t just a leg workout. Your core muscles—like the rectus abdominis, obliques, and lower back muscles—are activated to maintain stability and posture as you move. After your first run you may be surprised how many parts of your body may feel sore.

The upper body also plays a role, albeit a supporting one. Muscles of the arms, shoulders, and back work in harmony to counterbalance the actions of the lower body. This coordinated movement aids in maintaining rhythm and conserving energy during the run.4 Think of your arms as the pendulum of a clock, providing balance and momentum with each stride. It may seem small but expert runners fine-tune their running by finding the perfect arm swing and posture. When running long distances good posture and energy conservation pay dividends.

Build Muscle From Running: Abs and More

Running primarily targets fat loss rather than muscle gain. However, because it activates the core muscles, consistent running—especially with good form—can lead to a more defined midsection.5 While it’s not the most effective way to build bulky muscles like weightlifting, running does lead to muscle endurance and some degree of muscle toning in the legs and glutes.

Besides aesthetics, running has impressive health benefits. Regular runners often experience lower blood pressure due to improved arterial health and a stronger heart.6 A flattened stomach is more about reducing overall body fat than targeted exercises. So yes, combining running with a balanced diet can lead to a flatter stomach. Genetics also play a role in where and how you lose fat but pairing other workouts and stretching after running or on days you are not running is a perfect one-two combo to tackling fat loss and muscle gain.

Running Affecting Leg and Glute Size

Running, especially long-distance, enhances muscle endurance rather than bulk. For most individuals, consistent running tends to tone and slightly increase the size of the leg and glute muscles. However, the extent varies based on genetics and the type of running. Sprinters, who engage in short bursts of high-intensity runs, may develop more pronounced leg muscles due to the explosive nature of their training.7

If your goal is to tone without significantly increasing muscle size, focus on moderate-paced, longer-duration runs. And remember, diet also plays a crucial role. Consuming adequate protein and calories supports muscle growth and repair after runs. The smart athlete will know they “cannot outrun one’s fork”, that is, any calories burned during physical activity can quickly be added back by consuming more calories than were burned after their workout. Having a meal plan prepared for their running days, like a smoothie, or a salad and lean protein and sticking to it are crucial.

How Running Helps with Weight Loss

Running is a potent calorie burner. Depending on factors like weight, age, gender, and intensity, one can burn upwards of 100 calories per mile at even a low to moderate running effort.8 When you burn more calories than you consume, you create a calorie deficit, which leads to weight loss. Another advantage of running is the post-exercise oxygen consumption (EPOC), also known as the afterburn effect. This means even after finishing your run, your body continues to burn calories at an elevated rate, but intensity is key and requires a moderate to high-intensity workout.9

Remember, while EPOC does increase calorie burn post-exercise, it’s only one part of the calorie-burning equation. The majority of calories expended during workouts, especially high-intensity workouts, will still occur during the actual activity itself. EPOC is like a bonus, albeit a smaller one, to the total calorie expenditure. For those looking to lose weight or improve fitness, the main focus should still be on the exercise’s intensity and duration. The afterburn is just a beneficial side effect.

However, it’s vital to approach weight loss holistically. Simply adding runs without considering diet might not yield desired results. Pairing consistent running with a balanced, nutritious diet amplifies weight loss effects and ensures the body receives essential nutrients for recovery and overall health. Your body is a machine and it needs the right amount and right type of fuel, treat is well!

Ready to Lace Up

When selecting shoes, consider factors like your foot arch type, pronation, and the surface you run on. Visiting specialized stores with gait analysis services can provide insights into the best fit for you.

Choosing the Right Running Shoes

The foundation of a good run often begins with the right footwear. Picking the ideal running shoe is about much more than just style; it’s about enhancing performance and minimizing injury risk. The right pair of running shoes is pivotal for a comfortable running experience, and the perfect shoe caters to your unique foot structure, gait, and the terrain you run on however the jury is still out on if specialized running shoes prevent or injuries and thus the perfect shoe may be unique to each individual.10 Factors such as arch height, pronation (the way your foot rolls when you walk or run), and cushioning preferences come into play. It’s recommended to shop in specialized athletic stores where experts can analyze your foot type and gait, helping to match you with the optimal shoe.

Furthermore, considering how running shoes can wear out over time, it’s a good practice to replace them every 300-500 miles, ensuring consistent support and protection.11 Depending on frequency, this means replacing your shoes anywhere from every 6-12 months if your choice of running workout is a few 5K’s (3.2 miles) per week. Interestingly, a study has shown runners who practiced “shoe-rotation” incurred injuries at only 61% of the rate of injury of the group as a whole.12

What is “Shoe-Rotation”?

The act of extending footwear’s longevity by rotating between two pairs of shoes on alternate days. This practice gives the foam midsole time to decompress after each run, potentially extending the shoe’s lifespan and ensuring optimal performance.


While many global brands offer quality running shoes, some individuals prefer locally-made options. If you’re looking for running shoes made in the USA, brands like New Balance often have specific lines produced domestically. Regardless of the origin, ensure that the shoe provides adequate cushioning, support, and aligns with your running style and requirements.

Fun Facts and Other Unexpected Joys of Running

The elation of running isn’t only the excitement of movement but there are more physical and psychological effects that may surprise you.

Runner’s Trots: Why Running Makes You Poop

Running stimulates the bowels, thanks to the up-and-down movement and changes in blood flow to the gastrointestinal tract.13 For some, this leads to the infamous “runner’s trots” and you may find yourself heading to the bathroom the moment you get home from your run. To mitigate this, avoid heavy meals before a run and give digestion time post eating. On the bright side, if you’re feeling a little “backed-up” proper hydration and some light running can help loosen things up.

Runner’s High: The Euphoria of the Long-Distance Runner

Runner’s high is a term that many long-distance runners are intimately familiar with, and it’s not just a myth—it’s a genuine physiological response. So, what exactly is it? It’s defined as a feeling of euphoria, reduced anxiety, relaxation, and a reduced pain sensitivity, often experienced during or after extended physical aerobic exercise of at least 20 minutes.14 The distance required to experience a “runner’s high” varies from individual to individual. It’s not strictly about the distance, but rather the duration and intensity of the run, as well as individual biochemical responses.

For some, a runner’s high can kick in after just 20 to 30 minutes of continuous running, which could be around 2 to 3 miles (3.2 to 4.8 km) for many recreational runners. For others, it might take longer durations of steady, rhythmic running. However, it’s essential to note that not everyone experiences a runner’s high, regardless of the distance they run. Some people might feel it consistently during their runs, while others may have never felt it at all.

The science behind this phenomenon points towards the release of endorphins in the brain. Endorphins, often termed “feel-good” hormones, are natural painkillers produced in response to stressors, like the physical exertion of running. They can produce feelings of euphoria similar to that produced by opioids. Additionally, recent research suggests that another group of chemicals, endocannabinoids, might also play a role in this feel-good sensation.15

Besides the chemical boost, runner’s high can also be attributed to the sheer sense of accomplishment and the rhythmic, meditative state induced by consistent, prolonged running. It’s one of those experiences that’s hard to describe until you’ve felt it yourself, but once you have, it becomes one of the many reasons people get hooked on running.

The Right Fuel for Before and After Your Run

Fueling correctly is vital for runners. Before a run, opt for easily digestible carbs to provide energy. Oatmeal, bananas, or a slice of bread with honey are excellent choices. Runners of all distances typically avoid fatty or overly fibrous foods that might upset the stomach.16

Post-run, the goal is recovery. Focus on a blend of proteins to repair muscles and carbs to replenish glycogen stores. A smoothie with fruits, spinach, and protein powder, or a chicken sandwich, are nourishing options. Hydration is key—so don’t forget to drink water throughout.

Runner’s Fuel: Pre and Post Workout Meals

Pre-Workout Meal:

Goal: To provide a steady release of energy for the run.

  • Oatmeal Boost: A bowl of oatmeal topped with slices of banana. The oats release energy gradually, ensuring you don’t run out of fuel, while the bananas provide a quick energy boost. For a touch of natural sweetness and an added energy spike, drizzle some honey over the oatmeal.
  • High Quality H2O: Drink a glass of water about 30 minutes before you head out to ensure you’re well-hydrated before your run.

Post-Workout Meal:

Goal: To aid muscle recovery and restore energy reserves.

  • Smoothie Recovery: Blend together a mix of berries (like blueberries and strawberries) for antioxidants, a handful of spinach for vitamins and minerals, a scoop of protein powder to aid muscle recovery, and a banana to replenish potassium levels. Top it off with almond milk or water and blend until smooth.
  • Sandwich Delight: Prepare a chicken sandwich using grilled chicken breast (a lean source of protein) on whole grain bread. Add some lettuce and tomatoes for freshness and a boost of vitamins. The whole grains in the bread will help restore glycogen stores in your muscles.

Remember, rehydration is crucial after a run. Drink plenty of water in the hours following your workout to replace the fluids lost through sweat. This not only aids in recovery but ensures optimal muscle function and helps prevent cramps.

Crossing the Finish Line: Recap of Our Running Journey

As we reach the final stretch of our exploration into the world of running, let’s take a moment to jog our memories and revisit the milestones we’ve crossed. We delved into the transformative effects of running on the body, highlighted the myriad of muscles hard at work with every stride, and debunked myths surrounding running and muscle building. From understanding the enigmatic “runner’s high” to the scientific marvel of the “afterburn effect,” we’ve navigated the intricate maze of running’s impact on our health and well-being. And, of course, we stepped into the all-important realm of choosing the right running shoes and fueling our bodies pre and post-run.

Running, like any journey, is filled with highs and lows, challenges, and victories. But armed with knowledge and a passion for the path ahead, every step becomes a stride towards a healthier, happier you. So, lace up those shoes and set the pace, because the road ahead is yours to conquer. On your mark, get set, go!


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  3. Wang, Yuehan et al. “Leisure-Time Running Reduces the Risk of Incident Type 2 Diabetes.” The American journal of medicine vol. 132,10 (2019): 1225-1232. doi:10.1016/j.amjmed.2019.04.035
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  11. Malisoux, L.; Ramesh, J.; Mann, R.; Seil, R.; Urhausen, A.; Theisen, D., Can parallel use of different running shoes decrease running-related injury risk? Scandanavian Journal of Medicine & Science in Sports 2013.
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