Welcome to another edition of Triathlon research roundup. This series presents the most relevant and most interesting brand new research in triathlon, its three disciplines, nutrition, and all other things related to triathlon. You can find all other editions here.
We have a really mixed bag today, with performance tests, markers for overreaching, some news about protein, yelling on the bike and more.
For each study in the round-up, I’ll give a short summary of the main results and conclusions, and where relevant, my own interpretation and conclusions. There are links to the original sources of all studies, so you can see for yourselves if you're so inclined. Let's get into it!
This publication reviewed the available research about the need for post-exercise protein ingestion in masters endurance athletes. Current research suggests that masters endurance athletes recover from exercise induced muscle damage (EIMD) slower than younger, similarly-trained athletes due to a lower rate of muscle protein synthesis post-exercise.
The evidence about how to best counteract this by adapting protein intake is limited, but the "best guess" provided by these researchers is to consume doses of leucine rich, whey protein in the range of 35-40 g, or ~0.40 g/kg of body mass after muscle-damaging exercise. This is an interesting new finding; until now most recommendations have been to consume around 20-30 g of protein after hard exercise, whether you're a masters athlete or not. Additionally, it may be beneficial for masters athletes to consume at least four protein rich meals with similar doses of protein, as evenly spaced as possible.
It might be good to emphasize that this doesn't mean that you have to consume protein after every single workout - easy workouts of short to moderate duration don't induce muscle damage, so you don't need to stress out about this after such workouts.
This slightly odd study enrolled 23 moderately trained college-age, non-cycling athletes. Each of them did two incremental cycling tests to exhaustion, each on separate days. During one of the tests, the subjects were asked to produce loud yelling (in a predetermined fashion) when they became fatigued and/or respiratory rate and heart rate reached levels indicating hard effort.
The results showed that both peak power and time to exhaustion where significantly better for the yelling experiment compared to the control experiment (see table below).
A respiratory mask was used to measure several other variables as well. The most significant results were that stroke volume (measured as O2 pulse), rate of oxygen consumption (VO2) and CO2 expulsion were significantly higher in the yelling group, which explains the difference in performance output.
Finally, the degree of muscle activation of the vastus lateralis (the largest of four muscles compricing the quadriceps) was measured with EMG (electromyography), but was not significantly different between the groups.
This is a surprisingly interesting study that helps build the evidence for what most athletes already know anecdotally—that yelling can really be helpful to push through fatigue.
We're seeing a trend of more and more research focusing on finding root causes and risk factors of injuries in endurance sports, and the 1696-participant NLstart2Run study from the University of Groningen contributed with very valuable knowledge to this field of research.
During a 6-week period, the 1696 novice runners monitored running volume (minutes), frequency and intensity (rate of perceived exertion, RPE). These measures were then averaged every day for the last 7-day period, and calculations were done to relate these time-varying averages with the incidence of injuries.
The results showed that more intense training (RPE-average of the previous 7 days) was associated with a significantly higher risk of injury. This confirms previous research done and what we have known anecdotally for decades. There was a trend that running frequency (3 days instead of 2) was associated with greater risk of injury, although this trend was not statistically significant.
Most interestingly however, higher running volume (>60 min average duration) was associated with a lower risk of injury. Should beginners aim to go for longer runs than the norm, but keep them really easy to allow their bodies to adapt to the stresses of running and prevent injury by exposing themselves to running in a controlled, low-intensity fashion? These results indicate that that might be the case.
It would be interesting to see a similar study, but with a longer duration than 6 weeks, and see if the results would change at all as a result of that longer duration.
A systematic review from Australian researchers assessed the reliability and validity of different test protocols for measuring endurance sports performance. In this context, reliability means how consistently the tested variable (e.g. VO2max) can be determined, and is measured as a coefficient of variation (CV) in percentage units. Validity on the other hand refers to how well the test corresponds to true performance, and is measured using a correlation coefficient (from 0.00 for no correlation to 1.00 for perfect correlation).
The authors reviewed all previously published test protocols where either reliability or validity (or both) had been tested. In total, 18 previous publications with 28 test protocols were reviewed. All of the protocols reviewed were cycling or running tests. Reliability had been investigated far more extensively than validity, and one of the main takeaways of the review was that there is a need for more research on the validity of test protocols.
The article discusses multiple factors that affect the reliability and validity of tests. This provides very useful information both for people reading research papers who want to understand possible limitations of them, but also for researchers who are planning future study protocols.
One of the factors that impact most on reliability is whether the test is of time-trial or time to exhaustion format. Generally, the time trial format results in much better reliability. One very illustrative example of this was that a running time to exhaustion test (at average 5-km time-trial speed) had a variation (CV) of 11.2%, compared to 1.7% in a 5-km running time-trial. Reliability was also improved when well-trained subjects were tested, and when the subjects had the opportunity to familiarize themselves with test protocols and do pre-testing before the real test. Bouts of higher-effort intervals can be incorporated within test protocols without a significant decrease in reliability. Finally, tests can be reliably performed both inside a laboratory and outdoors.
The discussion about validity raises more questions than answers. Some things seem clear though; validity is directly related to reliability, test protocols should simulate specific race conditions in terms of hydration, intermittent bouts of higher effort (specifically for cycling, where this kind of racing is the norm), heat and wind conditions and the resulting convection, and again, time-trials generally result in good validity. The main conclusion however, is that there is a need for a lot more research to establish what test protocols are appropriate for good validity.
As the final entry of this post is a 1-year duration study where the stress and recovery of 20 female cyclists were regularly followed up and related to cycling performance. This is a welcome study, since there is still a lack of studies investigating the effect of stress and recovery on performance over a longer period of time, although there are plenty of shorter-term studies in this field.
General stress, general recovery, sport-specific stress and sport-specific recovery were measured 8 times during the year and then related to cycling performance as measured by three different parameters of a submaximal test; Power at the second stage (P80), power at the third stage (P90) and heart rate recovery after the test finished (HRR60 s).
The results showed that recovery-stress balance (recovery minus stress), lower emotional stress, higher sport-specific recovery, higher general stress, fatigue, physical complaints and higher social stress were all statistically significantly related to performance as measured by one or several of the performance metrics listed above.
These results are very expected, and provide further supporting evidence for the well-known saying:
"Workouts don't make you stronger, recovering from workouts makes you stronger."
Well, I hope you found this interesting, and maybe even found something you can apply yourself (yelling?). You can ask for clarifications in the comments below, or just send me an e-mail.
Finally, most triathletes know some other triathlete who is a real sucker for the science of triathlon. If you do know somebody like this, I'd like to ask you specifically to share this post to that person. Until next time!
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