Dynamic stretching trumps static stretching for kicking a soccer ball

THANK YOU FOR VISITING SWEATSCIENCE.COM!

As of September 2017, new Sweat Science columns are being published at www.outsideonline.com/sweatscience. Check out my bestselling new book on the science of endurance, ENDURE: Mind, Body, and the Curiously Elastic Limits of Human Performance, published in February 2018 with a foreword by Malcolm Gladwell.

- Alex Hutchinson (@sweatscience)

***

A pretty straightforward study from researchers in Malaysia, just posted in Journal of Strength and Conditioning Research. They took 18 professional soccer players and analyzed their kick on three separate days, after a warm-up that incorporated static stretching, dynamic stretching, or no stretching. Their range of motion during the kick was 1.67 degrees worse after static stretching and 8.38 degrees better after dynamic stretching compared to the no-stretch condition, a difference that was significant with p<0.01. Since higher range of motion correlates with greater angular velocity in the kick, the researchers conclude that dynamic stretching is better than static stretching for soccer players.

Here’s how they describe the dynamic stretches used:

Subjects performed the dynamic stretches… for 30 seconds at a rate of approximately 1 stretch cycle per second… The dynamic stretches used involve the Quadriceps femoris (quadriceps); Lateral lunge (adductors); Hip extensors (gluteals); Hamstrings (hamstrings); and Plantar flexors (gastrocnemius) described in Yamaguchi and Ishii.

Err, thanks for that. Fortunately, Yamaguchi and Ishii actually have a pretty helpful description:

Dynamic warm-up restores power lost in cold temperatures

THANK YOU FOR VISITING SWEATSCIENCE.COM!

As of September 2017, new Sweat Science columns are being published at www.outsideonline.com/sweatscience. Check out my bestselling new book on the science of endurance, ENDURE: Mind, Body, and the Curiously Elastic Limits of Human Performance, published in February 2018 with a foreword by Malcolm Gladwell.

- Alex Hutchinson (@sweatscience)

***

I ran a trail race last weekend that involved a waist-high creek crossing through pretty cold water. Climbing the long uphill after the creek, my legs were suddenly dead — I felt like I could barely get my feet a few inches off the ground. So I sympathize with the volunteers in this study, published online ahead of print in the Journal of Strength and Conditioning Research by researchers at the University of Connecticut.

The researchers used vertical jump to measure leg power in a group of NCAA D1 athletes, with three main purposes: (1) to see how much power would increase after a dynamic warm-up, (2) to see how much power would decrease if the subjects were pre-cooled by standing waist-high in 12 C water, and (3) to see if the dynamic warm-up could off-set the negative effects of cooling — something that would be of interest to athletes who compete in cold temperatures.

Everything was pretty much as expected. The dynamic warm-up increased jump power by 5%, and the cold water decreased jump power by 21%. When the subjects did a dynamic warm-up after cold-water immersion, they regained 70% of the lost power — not perfect, but still good to know.

Leaving aside all this cold-water stuff, the main reason I’m posting this is highlight the ever-stronger consensus that dynamic warm-up is the way to go. As the researchers note in their introduction:

Traditionally, static stretching exercises have been used by many coaches to prepare athletes for sporting activity. However, studies have shown that static and proprioceptive neuromuscular facilitation (PNF) stretching may negatively impact jump performance and power output. Dynamic warm-up exercises now appear to be preferred after many studies have compared the 2 modes and demonstrated dynamic exercises to be much more effective.

So what does that mean in practical terms? Well, here’s the dynamic routine the researchers used:

Continuous warm-up 1 (20 yds)
1. Arm circles forward X 1: walking forward on the toes while circling the arms forward with the arms parallel to the ground
2. Backward heel walk w/arm circles backward X 1: walking backward on the heels while circling the arms backward with arms parallel to the ground
3. High knee walk: walking forward and pulling the knee up to the chest with both arms, alternates as you walk
4. High knee skip: skipping forward and bringing the knee up so that the quadricep is parallel to the ground
5. High knee run: running while focusing on bringing the knees up so that the quadricep is parallel to the ground
6. Butt kicks: running while bringing the heel to the glutes
7. Tin soldiers: walking forward and kicking a single leg up in front while keeping the knee locked in extension (alternates)
8. One leg SLDL walk forward X 1: walking forward with straight legs, lean forward on 1 leg and reach for the foot with the opposite hand
9. 1 Leg SLDL Walk Backward X 1: walking backward with straight legs, lean forward on 1 leg and reach for the foot with the opposite hand
10. Backward skip: moving backward and skipping at the same time
11. Backward run: running backward and extending the rear foot behind you
12. Back peddle: moving backward while shuffling the feet and keeping them low to the ground
13. Overhead lunge walk: hands on the head while doing walking lunges forward
14. Inchworm: starting in the push-up position, walk the feet into the hands; then walk the hands out to the push-up position

Pre-run stretching doesn’t affect injury rate

THANK YOU FOR VISITING SWEATSCIENCE.COM!

As of September 2017, new Sweat Science columns are being published at www.outsideonline.com/sweatscience. Check out my bestselling new book on the science of endurance, ENDURE: Mind, Body, and the Curiously Elastic Limits of Human Performance, published in February 2018 with a foreword by Malcolm Gladwell.

- Alex Hutchinson (@sweatscience)

***

In the “I didn’t know they did research” department, U.S.A. Track and Field just released the results of a study on pre-run stretching. They recruited 1,400 runners through their website for a randomized, prospective study in which half the volunteers stretched before running and the other half didn’t. Over the next three months, 16% of the runners got injured, with no difference whatsoever between the stretching and non-stretching groups.

You can’t read too much into a volunteer, self-reported study like this, but if you drill a little further into the data, there are some interesting wrinkles. Age, sex, weekly mileage, flexibility and level of competition all had no effect on injury rates. High BMI and previous history of injury, on the other hand, both led to a higher probability of injury.

Most interestingly, people who normally stretch before runs but were assigned to the non-stretching group actually doubled their risk of injury. There’s not really enough detail in the study to understand why this happened, but it underscores an important message that applies not only stretching, but to other hot topics like running shoes: If you’re running happily without injury problems, don’t change what you’re doing!

The science of proper warm-up

THANK YOU FOR VISITING SWEATSCIENCE.COM!

As of September 2017, new Sweat Science columns are being published at www.outsideonline.com/sweatscience. Check out my bestselling new book on the science of endurance, ENDURE: Mind, Body, and the Curiously Elastic Limits of Human Performance, published in February 2018 with a foreword by Malcolm Gladwell.

- Alex Hutchinson (@sweatscience)

***

Gina Kolata has an article in the New York Times on whether warming up improves performance that’s worth a read. Overall, her message seems to be that there’s very little evidence about whether warming up helps or hurts performance, or does nothing. To reach this conclusion, she relies largely on a recent review by Andrea Franklin at Bloomberg University of Pennsylvania, which begins with this statement:

The value of warming-up is a worthy research problem because it is not known whether warming-up benefits, harms, or has no effect on individuals.

I agree that there’s lots of research that needs to be done — for example, there have been several interesting recent studies looking at the effects of dynamic warm-up activities as opposed to traditional static stretches, but more is needed to identify what works best for different activities and what the mechanisms are. But I think it’s a little melodramatic to claim that we have no idea whether warming up helps. Even Franklin describes her analysis of 32 “high-quality” studies as follows:

Warm-up was shown to improve performance in 79% of the criterions [sic] examined. This analysis has shown that performance improvements can be demonstrated after completion of adequate warm-up activities, and there is little evidence to suggest that warming-up is detrimental to sports participants.

That seems to be quite a bit more positive than the opening sentence, to say the least. There’s still lots to learn about warm-ups, but let’s not exaggerate our ignorance.

Jockology: some (but not all) pre-run stretching slows you down

THANK YOU FOR VISITING SWEATSCIENCE.COM!

As of September 2017, new Sweat Science columns are being published at www.outsideonline.com/sweatscience. Check out my bestselling new book on the science of endurance, ENDURE: Mind, Body, and the Curiously Elastic Limits of Human Performance, published in February 2018 with a foreword by Malcolm Gladwell.

- Alex Hutchinson (@sweatscience)

***

I posted last month about a new study on how static stretching before your run makes you slower and less efficient. To find out more about the study, I got in touch with the lead author, FSU’s Jacob Wilson. The result is this week’s Jockology column:

For years, researchers have been finding that the more flexible you are, the less efficiently you run – a message that tradition-bound runners have been reluctant to hear. Now, research to be published later this year in The Journal of Strength and Conditioning Research makes it clear that some (but not all) prerun stretching makes you slower. [read the whole article]

The most significant new piece of news in the article is that Wilson and his colleagues have just finished a follow-up study, in which they used the exact same protocol to study dynamic stretching. They’re still completing the analysis, but the results appear to show no significant decrease in performance for pre-run dynamic stretching. This means that you can still get your flexibility fix before a run without compromising performance — you just need to use dynamic stretches instead of static ones. (Some examples, with illustrations, are provided in the Jockology article.)

Drilling deeper into the dynamic stretching data, Wilson said it appeared that the most experienced runners weren’t affected by the pre-run stretches. Less experienced and less fit runners, on the other hand, still saw a bit of performance decline, probably because the unfamiliar stretches fatigued them a bit. So make sure you practice these stretches before trying them in a race situation. (This last stuff is very preliminary, so it may not be statistically significant — we’ll have to wait until the study is published to see.)