The researchers analyzed various checkpoints along a 161km ultra-marathon and took samples from several thousands of participants. The researchers examined foot strike, stride length, stride frequency, and even took blood samples.

Creatine Kinase Levels

Most of the participants were heel strikers. The heel striking tendency increased by about nine percent at the beginning of the race and then dropped to four percent during the race. When they analyzed the blood samples, the researchers found greater creatine kinase activity in midfoot and forefoot strikers as the race went on, which is a possible explanation for this effect.

Creatine kinase is a blood marker for muscle damage. In this case, muscle damage is essentially equivalent to muscle exertion. Since creatine kinase was higher in those who didn’t run with a heel strike, and since heel striking became more prevalent during the race than it was at the start, it’s safe to say that heel striking required less muscular effort to maintain.

Elite Runners and Foot Strike Patterns

Don’t abandon your attempts at mid- or forefoot striking just yet, however. Although non-heel strikers did experience a greater need for muscular control, and perhaps even a slightly greater cost of energy as a result, non-heel striking may have helped to make the top runners elite. By the final checkpoint where foot strike patterns were analyzed, thirty percent of the top twenty runners (six total), were using a forefoot or midfoot strike instead of a heel strike. Although there seemed to be no relationship between foot strike and speed, when you look at all the runners together, you see the fastest were more likely to be midfoot and forefoot strikers.

Elite runners are more likely to spend time on their running form, and thus might be more willing to spend the time on a different sort of foot strike. This could be a confounding factor in the results of elite foot striking patterns. They would also be better able to handle the physical demand of the different foot strike.

This fact seems true when looking at the other data in this study. The top twenty finishers had more stable stride rates and stride lengths. Stride length in particular didn’t change much at all and would be a critical part of their form. By contrast, the other finishers experienced greater changes, including an increasing stride frequency throughout the race and a reduced stride length.

The Uphill Factor

It’s important to note this was a hilly course, and hills increase the technical demands of distance running. For example, when running uphill, the ground meets the front of your foot faster than the back, increasing the prevalence of forefoot striking. Enough uphill running might cause a preference for that type of foot strike, even once the road flattens. The opposite may be true for downhill running, which is more technically demanding for a non-heel striker.

The researchers concluded that both harmful impact and muscular damage should be avoided during an ultramarathon. Since heel striking reduces damage, while non-heel striking reduces impact, they deemed foot strike a variable that should progress naturally. However, since elite runners have more stable form, and thus less muscle damage, I’d recommend not taking the researchers’ advice. Reducing impact is more important when developing the conditioning to handle the race length you like. I would advise ultrarunners to develop a more technical foot strike, rather than heel strike.

References:

1. Mark Kasmer, et. al., “Foot Strike Pattern and Gait Changes During a 161-km Ultramarathon,” Journal of Strength and Conditioning Research, 28(5), 2014

Photo courtesy of Shutterstock.

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When taken to an extreme, any form of exercise can be harmful to health. Whether you look at bodybuilding, powerlifting, or CrossFit, too much of anything is a bad thing. Overtraining syndrome is perhaps the first problem that comes to mind. Injuries might be the next thing you’d think of. Extreme exercise might even be damaging to the organs.

When it comes to endurance training, however, the boundary between working hard at your limits and pushing into an unsafe zone is unclear. Unlike many weight lifting programs, endurance training is supposed to be high volume. In fact, higher volume seems generally to be better for fitness. Compared to hitting the weights, the cutoff point for healthy, productive endurance training is ambiguous at best.

It’s interesting to compare the University of Copenhagen study to another study that I’ll refer to as the ULTRA Study, which tracked the health status of over 1,000 ultra-endurance runners. In the ULTRA study, injuries were found to be the most common problem reported for runners who said they wouldn’t run an ultra-marathon again. Injury rates could be a good measurement tool for determining health consequences. However, there were only eight of these individuals out of 1,000 participants, and they were all still running regularly. That’s not a very damning health concern.

The runners in the ULTRA Study ran a little less than six miles per day on average. That’s more than most people, but not what I would consider extreme. In the University of Copenhagen study, the runners participated in a multi-stage race that consisted of a full marathon every day for seven days. That’s an amount of exercise I would consider pretty extreme.

The researchers in the Copenhagen study noted the most commonly cited problems with ultra-endurance running are usually muscle damage, liver damage, electrolyte disturbance, and increased cortisol. Prior to the first day of racing the researchers took blood samples of the participants to determine a base-line measurement in each of these common problems, which they then compared to blood samples taken after the event.

The tests indicated very few problems whatsoever, and the problems they did find were insignificant. There was an increase in markers for muscle and liver damage, but the amounts were minor. There was no indication of greater damage than that found during less extreme exercise, and the markers of liver function were still strong. There was also no change in electrolytes or cortisol after the week-long event.

So the running wasn’t damaging. Further, the runners had lower body fat, greater lean muscle mass, and improved cholesterol at the end of the race. This means they experienced measurable health improvements after only seven days, which is a substantial result considering the runners in the study were highly trained competitors.

The race in the Copenhagen study was done on a flat course in mild weather. The racers had mandatory daily breaks, including time for sleep, and could eat and drink freely. Since some of the existing literature indicates health problems, it may be that extreme conditions with little rest may place a more substantial burden on the body. If you do enjoy ultra-endurance racing and training, it seems to be safe as long as the conditions are good.

References:

1. Kristian Karstoft, et. al., “Daily Marathon Running for a Week—The Biochemical and Body Compositional Effects of Participation,” Journal of Strength and Conditioning Research, 27(11), 2013.

2. Martin Hoffman, et. al., “Exercise Behavior of Ultramarathon Runners: Baseline Findings From the ULTRA Study,” Journal of Strength and Conditioning Research, 27(11), 2013.

Photos courtesy of Shutterstock.

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A team of French, Swiss, and Italian researchers studied 25 male participants in Italy’s Tor des Géants.¹ Possibly the world’s most difficult single-stage mountain ultramarathon, the TdG covers 330 kilometers (about 205 miles) with about 24,000m (about 78,700 feet) of elevation change. The record finishing time is about 76 hours, and participants are capped at a maximum time of 150 hours. As a single-stage race, rest and recovery time count against a participant’s total time. Runners typically suffer from substantial sleep deprivation in addition to the physical demands of the race.

Because the race is so long, the brief time needed to take blood samples and perform other measurements was not a major contributor to participants’ overall time, and researchers were able to test athletes at the midpoint of the race as well as before and after. At each point, researchers measured the maximum voluntary contraction force of the knee extensors and plantar flexors, as well as central and peripheral nervous system responsiveness. They tested blood samples for creatine kinase and other markers of muscular damage and inflammation.

Of the 25 participants, fifteen finished the race. Nine of those had measurements taken at all three opportunities. The researchers themselves served as the control group, subjected to sleep deprivation but not to the race itself.

Both the mid-race and post-race results indicated significant muscle damage and maximum voluntary contraction force loss. Peripheral nervous system response was unaffected, while central nervous system response deteriorated. Based on their own findings and previous research, the researchers believe that impairment of the excitation-contraction coupling mechanism is the primary contributor to neuromuscular fatigue in such extreme events. These effects were not seen in the control group, confirming previous work showing that sleep deprivation has little effect on neuromuscular response.

Next, the researchers compared their own results to a similar study of participants in the Ultra-Trail du Mont-Blanc (UTMB), a race about half as long as the TdG over similarly challenging terrain.² They found that runners at the midpoint of the TdG had suffered less muscle damage and neuromuscular fatigue than UTMB finishers, even though both groups had completed similar distances at that point.

The difference, they believe, is due to difference in pacing strategy. The mean flat terrain-equivalent speed over the TdG distance was 5.5±2.8 km/h (3.4±1.7 miles/h), compared to 7.2±1.3 km/h (4.8±0.8 miles/h) for the UTMB. Thus, the rates of eccentric contraction and joint loading are lower, reducing the rate of muscle damage. Indeed, TdG finishers had lower creatine kinase levels than UTMB finishers. The longer distance, with more elevation change, was actually less damaging for participants.

Few athletes participate in events requiring continuous effort over several days. Nonetheless, the drop off in muscle damage with reduced intensity, even with extremely high duration efforts, may have implications for recovery and rehabilitation protocols beyond the ultramarathon world.

Reference:

1. Jonas Saugy, et. al., “Alterations of Neuromuscular Function after the World’s Most Challenging Mountain Ultra-Marathon,” PLoS ONE 8(6): e65596 (2013).

2. Guillaume Y. Millet, et. al., “Neuromuscular Consequences of an Extreme Mountain Ultra-Marathon,” PLoS ONE 6(2): e17059 (2011).

Tor des Géants photo courtesy of F.cadioli (Own work) [CC-BY-SA-3.0], via Wikimedia Commons.

Ultra-Trail du Mont-Blanc photo courtesy of Pierre Thomas (Salomon) [GFDL or CC-BY-SA-3.0-2.5-2.0-1.0], via Wikimedia Commons.

The post Run Further, But Hurt Less? Reduced Muscle Damage Seen in Ultramarathons appeared first on Breaking Muscle.

However, it looks like our beliefs about when to start, how much to train, where to train, and so forth might not actually hold water. In a study this month in the Journal of Strength and Conditioning, researchers looked at the habits of 1,345 ultramarathoners. While it is known that ultramarathon participation is on a rapid ascent in recent years – there was a 22% increase just from 2011 to 2012 – very little is known about the ultramarathoners themselves and their training habits.

Age is one of many factors the researchers considered. The average age to run an ultramarathon for the first time was 36, which has held fast for decades. The second most common age to do an ultra for the first time was forty, and the average participant was 43. Over 10% of the participants were over fifty years old when they ran their first race. That means ultramarathons are not a young (wo)man’s sport.

The researchers looked at a lot of other demographic information as well, including gender and nationality of ultramarathon runners. 31.7% of the participants were women. A majority of the participants (87.7%) were American, with most of the rest coming from Europe and Canada.

On average, the athletes had been running for sixteen years. So, on average, they began running regularly in their late twenties, but not necessarily competing. However, 25% of the participants had only been running for three years or less before their first ultramarathon. Inexperience could account for some of the injuries seen, but this data also indicates that the sport is safely and commonly started relatively late in life, compared to other sports.

The researchers also looked at how much the runners trained. The average running distance in the prior year amounted to 3,347km. Since most of the participants were American, that might be better understood as averaging about forty miles of running per week. This volume didn’t show a significant decline with age, nor was it any different between men and women.

Training intensity, surface, and race frequency varied, but the researchers did note some trends. 61.9% of the runners’ training time was spent at a moderate intensity, meaning enough to break a sweat in ten minutes, which would be about race pace. About half of the time was spent on a trail, with another 42.5% spent on concrete or asphalt. On average, the runners did three marathons or shorter races and three ultramarathons in the prior year.

With an advanced training age and so many miles put in, we might think injuries and burnout would be common. However, out of everyone who had not completed an ultramarathon in the last year, most of the athletes intended to run again and cited other commitments as the main reason for not competing. For those who stopped running altogether, injuries were the main reason (accounting for only 2.7% of total participants), but commitments and unrelated medical issues together were more commonly cited.

The only group in which injuries were truly the most common reason for no longer competing was the group that still ran regularly but would not compete again. There were only eight people in that group, out of the 1,345 studied.

While novices need to be careful when competing for the first time, it seems that ultramarathons can be safe competitions for athletes of any age, sex, or experience level. Might be time to give it a shot.

References: 

1. Martin D. Hoffman, et. al., “Exercise Habits of Ultramarathon Runners: Baseline Findings from the ULTRA Study,” Journal of Strength and Conditioning Research DOI: 10.1519/JSC.0b013e3182a1f261

Photo courtesy of Shutterstock.

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