The Role of "Clustering" in Running-Related Injuries

If you are like most people, you do the majority of your long runs on the weekend. The typical 9:00-5:00 work day leaves little time to squeeze in anything over a 5 mile run during the week, especially this time of year, when the days are getting shorter. The result is often a behavioral phenomenon called clustering, which refers to performing a large portion of our physical activity (in this case, running) in a short period of time. Think of the runner training for a marathon, getting out for 5 mile runs 3 days per week due to time constraints, before performing a 20 mile training run on the weekend. The long run for this individual would be over 50% of the weekly training mileage, which puts them at an increased risk of injury. When considering how to organize or arrange our training mileage for a given week, we want to consider the 70/30 rule, which states that our long run each week should not exceed more than 30% of our total weekly training mileage, while the mileage from the rest of our training runs should add up to at least 70% of our total weekly training mileage. Following the 70/30 rule helps to promote consistency, creating a better environment for your tissues to adapt gradually over time. Following this rule also helps to promote specificity in training, as we need to consistently run long distances in order to run long distances well. In other words, running 5 miles is not the best way to help you run 26.2 miles well. Rather, running distances as close to 26.2 miles consistently will preferentially help you run 26.2 miles well. While training speed does not apply to the 70/30 rule, specificity applies to speed as well: training fast is the best way to help you run fast (i.e. training slow does not help you run fast).

Now there are a lot of other rules out there we are instructed to follow when training: the 10% rule (do not increase your weekly training mileage by more than 10% per week), the 40 mile rule (training beyond 40 miles per week increases your risk of injury), the 6 days per week rule (running 6 or more days per week increases your risk of injury, the 13 mile rule (running 13 miles or more for your long run more than once over a 2 week period of time increases your risk of injury). Finding a training program that adheres to all of these rules can be rather difficult so it is important to note that these are simply rules designed to help reduce our risk of injury and breaking them does not guarantee that we will get injured. The key is to follow the rules that seem to have the greatest impact on how we run. For example, if you consistently notice running over 40 miles per week tends to result in your knee hurting, but you can run every single day of the week without issue, the 40 mile rule may be important to adhere to, while the 6 days per week rule might be one you can ignore. Consistency seems to be one of the more important aspects of training though, which is why the 70/30 rule and the concept of clustering are so relevant. Big outliers in our training tend to result in tissue irritation or injury. A consistent training program, with slow and methodical increases built in will help you progress at the safest and fastest rate possible because this allows you to minimize your risk of injury. Getting injured is a sure way to slow down your training program, which will ultimately slow down your progress. In other words, you need to progress slowly in order to progress as quickly as possible.

Train smart!

-Grant Hennington, DPT

By The Numbers: Injury Risk In Runners

Running is a tremendously popular sport, with approximately 40 million people running regularly in the United States. This is not particularly surprising given all of the well-documented health benefits of this form of physical activity. Unfortunately, running also carries with it a high rate of injury, with up to half of runners experiencing an injury on a yearly basis. While many factors play into this high rate of injury among runners, two primary risk factors stand out: history of previous injury and overtraining. With these in mind, here are some important numbers to be aware of when designing or following a training program.

• 40

  • Multiple studies have shown that running greater than 40 miles per week significantly increases the risk of injury

• 13

  • Runs longer than 13 miles should be done no more than once every 14 days, as exceeding this significantly increases the risk of injury

• 10%

  • While this number is hotly debated due to inconsistent evidence, it is generally accepted that increases in weekly training mileage should not exceed 10% per week, as doing so increases the risk of injury

• 6

  • Running 6 or more days per week significantly increases the risk of injury

• 4-5

  • With respect to injury, most regular runners do best when training no more than 4-5 days per week, with at least 1 day of rest and 1-2 days of cross-training built in

• 2-3

  • Runners should limit themselves to no more than 2-3 marathons per year

Keep in mind that these are numbers from a variety of prospective and retrospective studies on specific populations of runners and may not directly apply to you. However, they do help provide metrics for you to use when evaluating your own training program, whether it be for your first 5k or your attempt to qualify for the Boston Marathon. In general, most training programs should progress slowly, incorporate rest days, and include cross-training exercises that promote improved strength and stability. It is difficult to enjoy running when injured so keep these numbers in mind, as they may help you lower your overall risk of injury when training for your next race.

Run safely!

-Grant Hennington, DPT

How To Select A Pair Of Running Shoes

Asics. Brooks. Saucony. Nike. Hoka One One. Altra. The number of running shoe manufacturers we have access to is extensive. And with each running shoe produced, a hopeful declaration is made to the customer: run faster, hurt less, go farther. So how do we sift through the myriad of options and settle on the best running shoe for us? Here are a few helpful tips:

• Comfort is key

  • Millions of dollars have been spent researching and developing systems to help individuals select the perfect running shoe for them, within a particular line. Have you ever stood on a fancy pressure sensor at a shoe store geared at helping you pick out a shoe? This is in that vein. While this is not necessarily a bad thing, it may not be adding any value. Researchers have concluded that the best predictor of a running shoe being appropriate for the individual does not require fancy foot scans or pressure maps. Rather, the best predictor of a running shoe being appropriate for an individual is comfort. So simple. By in large, if you are attempting to decide between two different running shoes, evidence suggests the one that is more comfortable is the better option for you.

• Know the lingo

  • Do you know the difference between a stability shoe, a neutral shoe, and a minimalist shoe? Do you know what heel-toe drop refers to? Knowing the vocabulary and relevant measures within the running shoe industry can help you make more informed choices for yourself. For instance, a stability shoe aims to limit excessive foot motion during the running cycle, while a neutral shoe alternatively aims to maximize cushion. A minimalist shoe attempts to reduce the weight of the shoe in hopes of improving running efficiency and, subsequently, speed. Heel-toe drop refers to how much higher off of the ground your heel is as opposed to your toes when donning a running shoe. All of these are important factors to consider when selecting a running shoe, given that comfort still needs to come first.

• Be a bit of a skeptic

  • While some running shoes are more popular than others, there is no one running shoe that has shown to be superior to others at reducing injury risk or vastly improving performance, despite advertising campaigns claiming otherwise. By in large, the overall rate of running-related injury is relatively the same regardless of footwear. However, some running shoe designs have higher rates of certain types of injury, with lower rates of others. For example, the barefoot running craze resulted in an increase in production of minimalist running shoes, with claims of reducing your injury risk. While some minimalist running shoes have been shown to reduce the risk of knee pain, this comes at the expense of an increased risk of Achilles tendinopathy and forefoot stress fractures. The reason? Running in a shoe with less cushioning tends to move our strike pattern to more of a mid or forefoot strike, reducing the impact force on our knee while increasing the load to our forefoot and Achilles. While the injury profile may be changed, the overall injury risk is the same. So, be a bit leery of any particular shoe manufacturer’s claim that a specific shoe in their line will dramatically reduce your injury risk.

• Try on numerous pairs

  • Given that comfort is the most important factor in selecting an appropriate running shoe, it is integral that you try on a number of pairs of shoes from different manufacturers in order to find the best fit. Ordering running shoes online does not provide this opportunity. Even if you are purchasing the same line of shoes from a manufacturer, it is important to note that small changes can be made to the design and fit from year-to-year. And, your foot can change a bit over time. So, again, you must try on several pairs to find the best fit for you.

• Focus on the fundamentals

  • While selecting an appropriate running shoe is an important component within a training program, the most significant factor related to injury and performance is your training program itself. No shoe will protect you if you are running too much or increasing your mileage or speed too rapidly. You must stick to the tried-and-true principles of training in order to set yourself up for success. In other words, regardless of your footwear, there are no shortcuts to the finish line.

Happy shopping!

-Grant Hennington, DPT

Quick Tips To Avoid Over-Training

Who out there is currently training for an endurance race or athletic event? For those of you who are, are you battling any nagging aches and pains? Unfortunately, both competitive and recreational athletes are subject to injury and it is well established that the majority of symptoms related to your training program are most likely the result of over-training. Think of over-training as being synonymous with overuse, and overuse described as repetitive and excessive microtrauma that overloads various musculoskeletal tissues. More simply, tissue breakdown exceeds tissue repair, leading to injury. With respect to endurance sports such as running or cycling, over-training can include excessive mileage, a rapid change in intensity/pace, and/or a sudden increase overall training distance. In other words, too much, too soon, too fast. A recent study reported that approximately one-third of runners with injuries described that they had changed their running routines just prior to their injury development. Another study demonstrated that injured runners had an average progression in weekly distance prior to injury of 31%, whereas the non-injured controls had a progression of 22%.

So what can we do to minimize our risk of injury while progressing through a training program? Here are a few tips:

• Progress slowly

  • As touched on, the majority of overuse injuries follow sudden or significant increases in duration or intensity. When participating in endurance sports, such as running or cycling, we want to follow the 10% rule, which states that we should not increase our weekly training mileage by more than 10% week-to-week. For example, if I run 20 miles this week, next week I should run no more than 22 miles in order to minimize my risk of injury while still adding mileage.

• Listen to your body

  • Think of pain as an alarm system within our body, alerting us of a potential injury to our tissues. Pain experienced in conjunction with your training program could be your body’s way of warning you of an impending injury if you continue to push it. Avoid taking medications like ibuprofen before a training run or workout, as to not impact your body’s ability to alert you of the need to stop.

• Mix it up

  • Many individuals focus on training for their primary sport nearly every day per week. This behavior stresses the same tissues in the same way day-in and day-out, leading to an increased risk of injury. Solution? Try participating in other physical activities or sports one to two days per week. For example, if you are a runner, try going cycling in order to get your cardio for the day. Or if you are a rock climber, take a day off and go to a yoga class. The key is using your body in a different way than you do in your typical training program.

• Take a break

  • While this is somewhat obvious, many of us are guilty of burying our heads in the sand and bucking this recommendation. Rest is important in both injury prevention and performance. Well rested tissues will function better than chronically overused tissues.

• Cool off

  • Applying a cold pack to a region of the body that is hurting after an intense workout can be an effective way to reduce or eliminate discomfort. This is a much safer long-term alternative to popping ibuprofen each and every day.

Happy training!

-Grant Hennington, DPT

Pronation: Not Always The Bad Guy

Physical therapists frequently analyze the running mechanics of individuals in a clinical setting, as running is an activity that carries with it a relatively high rate of injury. In fact, per athlete more injuries occur from running than from CrossFit, a sport with a reputation for being injury provoking. Far too often in working with runners, I hear many individuals talk about their tendency to pronate during the running cycle, as if pronation is a 4-letter word and the root cause of all running-related injuries. However, I’m here to tell you today that pronation is a perfectly normal and healthy aspect of the running cycle, allowing us to absorb shock and conform to undulations in the ground, as a pronated foot tends to be more pliable and flexible. Here is a synopsis of the foot position at various points in the running cycle:

• At initial contact (heel strike in approximately 80-90% of individuals), the foot is held in a supinated position, which means the arch of the foot is high and the foot as a whole is more rigid.

• As you transition from initial contact to a foot flat position, the foot transitions from a supinated position to a pronated position in order to quickly dampen the force from striking the ground and conform to the contours of the ground. An inability to pronate during this phase would expose the tissues in your foot to higher amounts of force, making running more uncomfortable. This would be similar to jumping off of a table and landing on locked knees.

• As you transition from a foot flat position to push-off, the foot must quickly transition back to a supinated position from a pronated position in order to efficiently propel you forward. As we mentioned earlier, a supinated foot is more rigid and a pronated foot is more flexible. A greater propulsive force can be generated by pushing off of a rigid foot compared to pushing off of a flexible foot. The inability to re-supinate the foot for push-off would feel similar to running in sand.

So as you can see, pronation is not a bad thing. Too much pronation or at the wrong times in the running cycle could be problematic, but that is true of supination as well. Furthermore, research on the link between pronation and running-related injury is a bit inconclusive. While it is true that some running-related injuries have been correlated with excessive pronation, there is some evidence that it can actually be a compensatory protective strategy in runners.

The foot has been shown to excessively pronate as a result of a lack of stability up the chain, typically at the hip joint. Therefore, it may not always be wise to simply jam an orthotic insert in your running shoes if you have been told you are “over pronating” when you run. A running analysis along with a thorough orthopedic physical therapy examination should precede any decision on the use of orthotic inserts or footwear selection. How we run is determined by more than just the foot and we need not blame all of our running aches and pains on pronation.

-Grant Hennington, DPT