Running is one of the oldest and most widely-practiced sports in the world for unsurprising reasons: we don’t need teammates, a facility, or rules. It’s debatable whether someone even needs equipment. Yet each year, as many as 70 percent of runners may suffer an injury.
Given the sport’s popularity and propensity for injury (ask any runner about their aches and settle in for a while), it’s shocking how little people have utilized science to optimize our performance and stay healthy. The amount of pseudo-science and “this worked for me so it must work for everyone” mindset that has infiltrated the sport is downright silly. As a physical therapist, I rely on evidence-based practice to help determine what’s most effective in optimizing health. For runners, that would be adding heavy strength training to their regular routine.
As of 2018, hundreds of studies have been conducted on the effects of strength training in runners of all abilities. As the body of evidence grows, it’s become increasingly clear that strength training does at least two things very effectively: it improves the efficiency of running and increases the body’s tolerance to loading muscles.
In order to understand why this is important, consider the basic biomechanics of running. Each stride is a hop from limb to limb assisted by forward momentum, which requires speed, control, and muscle strength to absorb impact and generate energy. If we lack any of these components, we sacrifice efficiency, or “running economy,” the energy cost of running at a given speed. To put the significance of running economy in perspective, let’s say the average male distance runner has a stride length of 74 inches. That means in just one mile, this runner will take 1,712 steps. Given that the 5k (3.1 miles) is the most common race distance worldwide, an inefficient stride may be repeated over 5,000 times. That’s a lot of energy left on the table. Even a tiny improvement in running efficiency goes a long way.
The amount of force that the muscles, joints, and other soft tissue structures in the lower body absorb during running is significant, especially in the knee, ankle, and foot. This force can be separated into three categories during running; cumulative load, peak load, and rate of loading. Basically, how long, how much, and how fast we load our tissues all matters in different ways. We can achieve similar levels of overall load from a high frequency-low intensity stimulus and a low frequency-high intensity stimulus (jogging for an hour versus playing basketball for 20 minutes, for example). Ultimately, if we load our tissues adequately and progressively, we adapt in a positive way. If we do too much too soon (looking at you, weekend warriors), our body doesn’t have the chance to adapt, and we risk overtraining injuries. At its fundamentals, running is a matter of tissue load capacity.
So what does all of this physics stuff have to do with strength training? Well, most running-related injuries go back to the principle of tissue capacity. If the load on our body exceeds its capacity, we get injured. After injury, our load capacity decreases; the 3.1-mile run that used to be easy causes pain (whether or not we even have true tissue “damage”).
We now have two courses of action. Number one: we can modify our training to accommodate our new load capacity. This means either running less or not running at all. This is the least fun course of action. Number two: we can improve our load capacity. Even if a runner dislikes strength training, it’s worth it to allow them to continue their regular running.
If staying healthy isn’t a good enough reason for a runner to lift weights, the benefits extend to enhanced performance. In a 2018 review of the highest quality strength training studies, runners saw improvements in race times, sprint speed, and running economy. While the mechanism isn’t fully understood yet, it’s likely that strength training improves our neural drive (brain-to-muscle connection), leading to improved running economy. As we train, each stride in the gait cycle costs less energy, letting us run faster, for longer.
Where does a runner begin when they want to start strength training? We know based on research that experienced runners can benefit from heavy strength training, specifically in the lower body. If someone has never lifted a weight before, heavy lifting is not recommended as the first step. Before we can develop moving heavy loads quickly, we have to do it slowly. Before we can move heavy loads slowly, we have to establish a baseline of good control, which means starting with a slightly higher repetition range and focusing on movement quality with less weight. Each individual will be starting at a different point based on a number of factors, but the end goal should be the same for all: heavy resistance training to improve load capacity.
The single most common misconception about heavy strength training in endurance athletes is that they will gain mass and lose efficiency. Luckily, nearly every research study on the topic measures body mass index (BMI) changes pre- to post-study. To date, there’s overwhelming evidence that body composition doesn’t change following several months of strength training with regular running.
Time is another barrier that often stands between runners and weights, but lifting doesn’t need to be a big commitment. Large effects are seen with a twice-per-week program, with improvements starting as early as six weeks. It doesn’t have to be three hours in the gym; hit the key running muscle groups (quadriceps and calves if nothing else), and you’ll set yourself up for success. Every runner, from recreational to competitive, can benefit from strength training. It is the single most effective running-adjunct activity to improve efficiency and reduce the risk of injury. Even if you don’t race or care about your time, injury risk management should be considered important, as it keeps you participating fully. You don’t have to like it, but if you love to run, pick up the heavy weights.
Dr. Jason Tuori, PT, DPT, CSCS is a licensed physical therapist at McCune & Murphy Physical Therapy.