1 00:00:06,450 --> 00:00:10,449 I've been a runner all my life, and I've run with shoes pretty much all that time. 2 00:00:10,449 --> 00:00:13,449 But as a result of this research, I thought I should try barefoot running, 3 00:00:13,449 --> 00:00:17,449 and I actually have to say I've really enjoyed it. It's been a lot of fun. 4 00:00:23,350 --> 00:00:25,350 Humans have been running for at least 2 million years, 5 00:00:25,350 --> 00:00:28,350 and of course for most of that time, humans were running barefoot. 6 00:00:28,350 --> 00:00:32,350 And modern running shoes were actually only invented in the mid-1970s. 7 00:00:32,350 --> 00:00:36,350 So we have this idea now that in order to run, all you need are a pair of shoes. 8 00:00:36,350 --> 00:00:38,350 It's a common statement, right? 9 00:00:38,350 --> 00:00:39,609 Well, actually, that's not true. 10 00:00:39,609 --> 00:00:40,509 You don't need shoes. 11 00:00:40,509 --> 00:00:41,689 You just need feet. 12 00:00:45,219 --> 00:00:47,539 There's probably two stages in the evolution of the foot. 13 00:00:47,539 --> 00:00:50,219 Initially, the foot evolved for walking 14 00:00:50,219 --> 00:00:52,280 and also to climb trees. 15 00:00:52,280 --> 00:00:53,960 But at some point in human evolution, 16 00:00:53,960 --> 00:00:55,799 we think around two million years ago, 17 00:00:55,799 --> 00:00:58,560 there was a big environmental change in Africa, 18 00:00:58,560 --> 00:01:00,200 and the woodlands started disappearing 19 00:01:00,200 --> 00:01:02,140 and the savannas started growing. 20 00:01:02,140 --> 00:01:04,500 And at that point, new foods started appearing, 21 00:01:04,500 --> 00:01:06,819 and one of them, of course, was meat. 22 00:01:06,819 --> 00:01:09,379 There were all these ungulates out there on the grasslands. 23 00:01:09,379 --> 00:01:13,459 And in order to become a hunter, I think humans started to evolve running. 24 00:01:14,099 --> 00:01:18,180 And what we're good at is running at speeds that make animals gallop. 25 00:01:18,560 --> 00:01:21,040 And if you do that in the heat for a long period of time, 26 00:01:21,560 --> 00:01:26,180 that animal will overheat because quadrupeds cannot pant and gallop at the same time. 27 00:01:26,659 --> 00:01:29,920 So imagine you're chasing a gazelle or a kudu or some big animal. 28 00:01:30,099 --> 00:01:35,599 If you can chase that animal, make that animal gallop for 10 to 15 minutes, you've got dinner. 29 00:01:40,659 --> 00:01:43,659 We wanted to figure out how people ran without shoes 30 00:01:43,659 --> 00:01:45,159 before the shoe was invented 31 00:01:45,159 --> 00:01:47,019 because people have been running for millions of years 32 00:01:47,019 --> 00:01:52,200 and we weren't really sure what happens when barefoot runners run 33 00:01:52,200 --> 00:01:53,900 and how well they can do it. 34 00:01:54,079 --> 00:01:57,760 So we started bringing in habitual barefoot runners into the lab 35 00:01:57,760 --> 00:02:01,340 just to see how they use their bodies and how they use their feet. 36 00:02:05,299 --> 00:02:05,959 All right, here we go. 37 00:02:06,079 --> 00:02:07,620 Three, two, one. 38 00:02:07,620 --> 00:02:24,409 What we discovered was that barefoot runners run often very differently from the way your 39 00:02:24,409 --> 00:02:26,750 typical shod runner runs. 40 00:02:26,750 --> 00:02:30,370 So the shoe has got a big heel and it's designed to make it very comfortable to land on your 41 00:02:30,370 --> 00:02:34,610 heel and so a lot of shod runners land on the heel and then they bring the rest of their 42 00:02:34,610 --> 00:02:45,659 foot down. 43 00:02:45,659 --> 00:02:50,000 So when you land again on your heel, your body comes to a dead stop, there's a lot of 44 00:02:50,000 --> 00:02:55,560 mass and so there's an impact, there's a rapid force. 45 00:02:55,560 --> 00:02:59,060 It's like somebody hitting you on the heel with a hammer about two to three times your 46 00:02:59,060 --> 00:03:00,280 body weight. 47 00:03:00,280 --> 00:03:04,419 So when we started bringing barefoot runners into the lab, we discovered that they didn't 48 00:03:04,419 --> 00:03:05,539 like to do that, right? 49 00:03:05,539 --> 00:03:10,960 They typically landed on the front of their foot pretty horizontally, not like that, but 50 00:03:10,960 --> 00:03:15,620 just a little bit, so that they land underneath the heads of the fourth and fifth metatarsal 51 00:03:15,620 --> 00:03:19,000 often, and then they bring the heel down. 52 00:03:19,000 --> 00:03:23,080 And when we ran them over force plates, we discovered that they didn't have that big 53 00:03:23,080 --> 00:03:37,960 spike, that impact transient, that is typically associated with a heel strike. 54 00:03:37,960 --> 00:03:41,240 So what barefoot runners tend to do is by landing more towards the front of the foot 55 00:03:41,240 --> 00:03:46,020 and then letting the heel come down afterwards, and what that does is it converts the energy 56 00:03:46,020 --> 00:03:52,240 that would otherwise be a dead stop, right, the vertical deceleration of the leg, it converts 57 00:03:52,240 --> 00:03:54,099 that into rotational energy. 58 00:03:54,099 --> 00:03:57,960 You can understand the difference with the following very commonplace observation. 59 00:03:57,960 --> 00:04:03,199 Imagine dropping the pen onto the ground but falling vertically down, that's like your 60 00:04:03,199 --> 00:04:07,060 heel strike where your entire leg strikes the ground and comes to a stop and it's a 61 00:04:07,060 --> 00:04:13,069 big impact force. 62 00:04:13,069 --> 00:04:18,050 On the other hand, if you're a forefoot striker then you can think of it like the pen landing 63 00:04:18,050 --> 00:04:22,529 at an oblique angle where it hits the ground and it doesn't come to a dead stop but starts 64 00:04:22,529 --> 00:04:23,529 rotating. 65 00:04:23,529 --> 00:04:27,850 So not all the kinetic energy of the pen has to be absorbed by the impact, some of it gets 66 00:04:27,850 --> 00:04:32,529 is transferred from moving down to rotation and so the impact forces are much smaller 67 00:04:32,529 --> 00:04:44,699 in a forefoot strike compared to a heel strike. 68 00:04:44,699 --> 00:04:49,439 A lot of runners get injured and what they get typically often are repetitive stress 69 00:04:49,439 --> 00:04:50,439 injuries. 70 00:04:50,439 --> 00:04:56,220 And so one hypothesis is that that impact caused by landing on the heel, which causes 71 00:04:56,220 --> 00:05:01,459 that big impact transient, could be injurious and it's associated with pain in the soft 72 00:05:01,459 --> 00:05:07,600 tissues at the bottom of the foot, it's associated with shin splints, may cause some other kinds 73 00:05:07,600 --> 00:05:08,899 of injury. 74 00:05:08,899 --> 00:05:13,899 So our hypothesis is that individuals who don't land on their heel, but avoid those 75 00:05:13,899 --> 00:05:19,000 big impacts by landing on the front of their foot, may be less susceptible to those kinds 76 00:05:19,000 --> 00:05:30,709 of repetitive stress injuries. 77 00:05:30,709 --> 00:05:34,009 So we've been studying barefoot runners now for quite a while, and we went to Africa, 78 00:05:34,009 --> 00:05:37,709 we looked at people who've never worn shoes, and they've been running 20 kilometers a day, 79 00:05:37,709 --> 00:05:40,370 and I just decided I had to try running barefoot myself. 80 00:05:40,370 --> 00:05:44,689 So I, last summer actually, I was running one day and I just decided to take my shoes 81 00:05:44,689 --> 00:05:49,310 off and I found it was just incredibly fun and since then I've actually started running 82 00:05:49,310 --> 00:05:52,029 barefoot frequently and I have to say I really love it. 83 00:05:52,029 --> 00:05:53,029 It feels great. 84 00:05:53,029 --> 00:05:58,430 I've stopped heel striking and I now have become a forefoot striker and it's fun.