How much performance boost are you getting from a wetsuit?

As many of us are aware, the swimming legs of most long-distance triathlons
are wetsuit legal, allowing athletes to don non-porous suits for the opening swim. Ostensibly, athletes wear these suits to stay warm in cooler water (generally less than 78 degrees Fahrenheit), but are generally worn for another reason: the increased volume, minimal additional mass, and streamlined characteristics of a wetsuit results in improved hydrodynamics, allowing athletes to move through the water both more rapidly and with greater ease. In this recent publication, a Japanese group set out to quantify the effect of wearing a wetsuit on individual athletes during two 5-minute swim trials at 60 and 80% of each athletes maximum oxygen absorbtion rate (previously determined). Here are their findings: On average, wetsuit wearers moved 5.4% faster than those wearing a speedo-style swimsuit, and experienced a 14.4 and 7.5% reduction in energy costs to acheive these results (at 60 and 80% respectively). The researchers also measured stroke length and stroke rate of the participants, and found that, while stroke lengths were similar, stroke rates were slightly higher in individuals wearing a wetsuit. The results of these findings suggest an inherent advantage in wearing a wetsuit during the swim. But that's not all. According to this study there is a significant difference in cycling power output (a whopping 12%) after a swim preceded by a swim in either a speedo or a full wetsuit. So... yet another reason to wear the wetsuit. If you don't have the funds to buy a fancy new wetsuit, there's always the poor man's option: drafting. As in cycling, there is a small efficiency gain when swimming behind someone else in their slipstream. This study measured that difference on a bike test preceded by either a drafting or non-drafting swim, and found that one typically produces 4.8% more power after drafting during the preceding 750 meter swim. And since I've never heard of a race that penalties you for drafting, I'd say go for it, even if you're wearing a wetsuit too!

New Predictor of Running Performance?

An interesting article recently published by a Swiss group finds an interesting new predictor for success in endurance running: the circumference of your upper arm. The researchers in this study measured runners participating in the "Deutschlandlauf" (a race covering 1200 km in 19 days!) for a broad variety of factors including age, body mass index (BMI), height, weight, skinfold measurements, and measurements of other anthropometric factors (such as calf and thigh circumference measurement). Amazingly, NONE of these correlated with performance in the event itself EXCEPT for measurement of the circumference of the upper arm. Obviously, a major message from this research is the idea that carrying around ANY mass (muscle or fat) not related to bipedal locomotion appears detrimental to running. The upper arm's relevance as a measuring point, though, is something of a mystery, as there can be great discrepancy in arm circumference, even among lean individuals. It would be interesting to look at the people who do well in local races of varying lengths and see if the correlation holds to shorter distances (say, less than 50 km or so for the more mortal of us).

Sadly, the full article isn't available online, but I've posted a link to the abstract.

Impact of Temperature on Running Performance

Everyone who's laced up their shoes for any period of time knows that some temperatures are better than other for running fast. The reason for this is simply energetics: the human body is a bio-organic engine, which generates waste heat (an elite marathoner burns over 1400 calories an hour during a race). We must dissipate this heat. If we don't, certain biochemical processes (notably in the brain and liver) are inhibited and we will tend to slip into comas (a phenomenon somewhat inappropriately called heat stroke). Our bodies dissipate heat predominantly through skin at a rate that depends on many things: surface area vs. body volume, AND the difference between body temperature and air temperature. In warmer weather. Most of us don't think about it, but colder weather also negatively affects us, as our blood vessels must dilate to circulate warm blood to cold hands, forcing our hearts to work harder. This recent study by Ely et al (sponsored by the US Army Research Institute of Environmental Medicine) addresses the former possibility in an analytical study asking just how much do higher temperatures negatively affect running performance in a marathon. To do this, the authors surveyed the finishing times of elite marathoners, as well as the 25th, 50th, 100th, and 300th finisher from various well-known marathons (including New York and Boston) and compared them to the course record (i.e., a 2:10 marathon is 8.3% slower than a 2:00 marathon). Finally, the authors examined these finishes in light of the official temperature conditions recorded at each race, breaking them down into four groups of temperatures:5-10, 10-15, 15-20, and 20-25C (that's roughly 41-50, 51-59, 60-67, and 68-77F). At the elite level, there was a progressive decline as temperature increased (an average of 1.7, 2.5, 3.3, and 4.5% slower than course record on average for each respective temperature category).

Unless your last name is Tergat, I've got some bad news for you: elite runners appear to be less affected by dramatic increases in temperature than the average person. The authors examined the finish times of more pedestrian runners, and found that their performance falloff to be more dramatic as temperature increased. For example: runners coming in 25th saw a slowing of 3.6% from the coolest temperature group to the warmest, very comparable to the 2.8% falloff observed in elite athletes. However, the 300th finisher exhibited a 7.9% falloff in the same conditions. Several possibilities exist for this discrepancy, including (a) a failure of less elite runners to acknowledge the conditions and accordingly modify their effort and/or (b) the existence of a threshold temperature over which performance suffers more dramatically and/or (c) inappropriate modification of hydration/nutrition/warmup strategies in less accomplished runners.

This article is the first I am aware of that quantifies the drop in running performance based on temperature. Overall, I find this to be a solid study with well-grounded statistical analysis and a sufficient sample population to draw conclusions from the data. One thing I would like to see in this study or a future investigation is an analysis of the effect of humidity. Since humans sweat to dissipate heat, drier conditions favor this approach, and I would be willing to wager an even more dramatic performance falloff occurs in high humidity environments. Even better: a comparison of heat, humidity, and elevation change on running performance- all the better to know where to go when looking for a personal record!

Long Term Impact of Exercise?

From the most recent edition of the journal of exercise physiology, a report that asks the following question: does participation in high level sports negatively impact your health in later years? In a straightforward study, the authors sent out questionnaires to "normal" and varsity athlete alumni of the University of Alabama, asking them a number of questions regarding injuries past and present, whether said injuries were chronic or acute, and the degree to which these injuries affected their lives. While varsity athletes suffered injuries at an alarming rate (approximately 50% by the studies measure), varsity athletes had chronic injuries that affected both their sport and nonsport lives at a rate roughly 5 to 6 times the rate of nonathletes.

Superficially, these results might suggest involvement in college sports carry severe health risks for later in life. Not necessarily! Interestingly, though it's not reported prominently in the study, varsity athletes from college participate in aerobic exercise an average of 3 times more (measured in hours per week) than non-varsity athletes. As the average age of respondents was between 40 and 41, two interesting observations emerge: First, athletes at a young age are more likely to maintain aerobic exercise habits long after their playing days are over. Second, these "former" athletes accomplish this despite an increase in virtually all sorts of injuries compared to their classmates. This is an interesting counterpoint to the risks of active involvement in sports later in life, one that the authors may not fully consider.

Getting Started

Hi all. This is the beginning of a new blog I am starting that I hope will fill a void that I perceive between sport and science. Essentially, I believe that there is a disconnect between research addressing significant aspects of training the human body (including physiology, endurance, recovery, and maximal performance among others) and those set to applying it (including amateur and even professional athletes and those who train them). In essence, cutting-edge research findings which may be very relevant to the average age-group athlete are either delayed or (worse) never reported in the mainstream press. The biggest obstacle to this reporting . Exercise research is rarely as sexy as the newest cure for cancer or AIDS, and individual athletes and/or their trainers rarely possess the technical expertise to survey and interpret the available literature. As a scientist and endurance athlete, I hope to do my part to close this gap, by perusing and reporting on the latest developments in sports science. Each month I will survey recent scientific publications for new reports of interest, and will post them here, along with commentary to make them more easily applicable to the average person's life. Thanks for reading, and I hope you enjoy.