Each month we compile a short-list of recently-published papers (full list here) in the world of running science and break them into bite-sized chunks so you can digest them as food for thought to help optimise your training. To help wash it all down, we even review our favourite beer of the month.
Welcome to this month's installment of our "Nerd Alert". We hope you enjoy it.
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Click the title of each article to "drop-down" the summary.
What was the hypothesis or research question?
Treadmill tests of short exercise durations have found reductions in central drive to muscles, indicative of central fatigue. I.e. running causes the brain to get tired of sending signals to the muscles to make them contract. Studies following longer duration races confirm this but methods used have been unable to distinguish between cortical activity (signals from the brain to the spine) and spinal activity (signals from the spine to the muscles). By measuring the Hoffmann reflex (H-reflex) and the first volitional wave (V-wave) after a voluntary contraction does allow for separation of cortical (V-wave) and spinal (H-reflex) signals. The authors did not state a hypothesis but the purpose of their study was to investigate how the H-reflex and V-wave of plantar flexion muscles in the calf (soleus and gastrocnemius) are modulated by trail running races.
What did they do to test the hypothesis or answer the research question?
— As a sub-study of a large study investigating fatigability at UTMB (Ultra Trail du Mont Blanc), 18 participants (10 men and 8 women) were analysed before and after 4 of the events at UTMB in Chamonix: the MCC (n=3; 40 km, 2300m gain), OCC (n=4; 55 km, 3500m gain), CCC (n=6; 100 km, 6100 m gain), and UTMB (n=5; 170 km, 10,000 m gain).
— Neuromuscular function was measured in all participants, who were first familiarized with the lab tests and then received all tests ~2 days before and ~45-mins after their race. All tests were completed in Chamonix.
— Neuromuscular function was assessed by:
→ maximal voluntary contraction (MVC) of the right plantar flexion muscles (i.e. measuring how much torque a person’s calf muscles generate when raising their heel in a seated position),
→ supramaximal intensity for tibial nerve electrical stimulation (lower leg nerve stimulation during MVC to determine how much torque a person’s calf muscle can generate involuntarily above voluntary effort), and
→ submaximal electrical nerve stimulations during 50% MVC (to determine how torque can be involuntarily boosted above a submaximal voluntary effort).
NOTE: Since I am not an expert in neuromuscular physiology, I cannot comment on the validity of these measures but the authors have many years of experience with these methods and provide a high level of procedural clarity in their manuscript to ensure they could be reproduced by others.
— The authors made a pooled data analysis from the 4 different race distances.
What did they find?
— On average, the participants were about 2x slower than the respective winners of the events.
— Maximal voluntary contractions were significantly reduced (-28.7±12.8%; p<0.001) with a huge
effect sizea quantitative measure of the magnitude of the experimental effect. Less than 0.5 is small, greater than 0.8 is large.
(d=2.11).
— V-wave was reduced in soleus muscle (-35.0±57.4%; p=0.003) with a large
effect sizea quantitative measure of the magnitude of the experimental effect. Less than 0.5 is small, greater than 0.8 is large.
(d=0.801) and in gastrocnemius medialis muscle (-28.4±60.9%; p=0.031) with a moderate
effect sizea quantitative measure of the magnitude of the experimental effect. Less than 0.5 is small, greater than 0.8 is large.
(d=0.56).
— The H-reflex did not change (p=0.577; d=0.134, trivial
effect sizea quantitative measure of the magnitude of the experimental effect. Less than 0.5 is small, greater than 0.8 is large.
).
— The authors conclude that, in the absence of concomitant changes in H-reflex amplitude, the decrease in V-wave amplitude may reflect a change in volitional drive (i.e. motoneuron discharge rate and/or recruitment). This has been previously suggested to arise following prolonged exercise due to hypoglycemia, decreased cerebral catecholamine levels, increased core temperature, cerebral ammonia accumulation, altered brain neurotransmitters levels, and afferent feedback.
— The findings indicate that the races caused central fatigue, likely due to cortical (V-wave) and not spinal (H-reflex) signal fatigue.
What were the strengths?
— Appropriate statistical procedures and reporting of
effect sizea quantitative measure of the magnitude of the experimental effect. Less than 0.5 is small, greater than 0.8 is large.
s as well as probabilities of effects.
— Clear methodological reporting enables others to replicate this study.
— Included men and women.
— A clever way to delineate supraspinal (cortical/in the brain) and spinal aspects of central fatigue following extremely fatiguing exercise — ultra-distance mountain racing.
— Data have a high level of ecological validity having been collected under real-life race-day conditions in one of the most extreme ultra-distance trail running events, UTMB.
What were the weaknesses?
— A very small sample that was pooled across 4 different race distances and elevation profiles.
— Since central fatigue can recover quickly after exercise, it remains unknown whether the 45-min delay in testing after the race misses the true result. But given the logistical difficulties of testing at a race, I doubt this delay could be shortened.
— No reporting of participants’ training status leading into the races or their nutritional status during the races.
— No measures of internal/external load during the race, e.g. a calculation of training impulse would help see how the within-race exercise dose compared among participants.
— Findings are only applicable to slower athletes (the participants' finish times were, on average, twice as slow as the winners of the races).
Are the findings useful in application to training/coaching practice?
No.
While the study is highly commendable for its high ecological validity and attempt to discern between supraspinal and spinal sources of central fatigue, knowing whether central fatigue manifests in the brain or the spine does not inform training or coaching practice. The reality of running 42km, 60km, 100km, or 170 km in the mountains is that you will develop both peripheral and central fatigue and your training should be designed to help you resist both for as long as possible. While we know how to help delay both types of fatigue, we currently do not know how to specifically train to resist supraspinal central fatigue.
What was the hypothesis or research question?
Little research has examined the various training protocols to use following a marathon that will best facilitate an athlete’s return to regular training. Based on some prior findings that running delays the recovery of soreness after a marathon, the authors hypothesized that, following a marathon, muscle damage recovery would be faster when resting or doing elliptical training compared to running training, whereas neuromuscular performance recovery would be faster with elliptical training.
What did they do to test the hypothesis or answer the research question?
— 98 runners participating in the 2016 Valencia marathon, aged between 30 and 45 with a previous marathon best between 3 and 4 hours for men and 3.5 and 4.5 hours for women, volunteered. Of these, 64 completed the post-intervention testing.
— At baseline, VO2max, running economy, and ventilatory thresholds (VT1 and VT2) were measured.
— After the marathon, participants were randomised to one of 3 groups: rest, run, and elliptical. The rest group did not exercise for 192-hours while participants in the run and elliptical groups exercised for 40 min at 48 h, 96 h and 144 h after the marathon. The 40-min sessions were at a moderate intensity — 95 to 105% of the heart rate corresponding to their first ventilatory threshold (VT1), which you might know as “aerobic threshold” — basically, their easy run pace.
— Blood samples were collected and neuromuscular performance (squat jump test) was measured before and after (15min and 24, 48, 96, 144 and 192 h) the marathon. In the run and elliptical groups, blood drawings and squat jump tests were performed immediately before the training sessions.
What did they find?
— Blood levels of creatine kinase (CK) and lactate dehydrogenase (LDH; markers of muscle damage) were increased following the marathon (moderate to large effects sizes, 0.88 and 0.69) and peaked 48-hours after the marathon but, contrary to the hypothesis, their recovery back towards baseline was not different between intervention groups (rest vs. run vs. elliptical).
— Neuromuscular performance (squat jump height) was reduced after the marathon (trivial
effect sizea quantitative measure of the magnitude of the experimental effect. Less than 0.5 is small, greater than 0.8 is large.
, 0.08). While the running group showed a moderate restoration of performance 96-hours after the marathon (
effect sizea quantitative measure of the magnitude of the experimental effect. Less than 0.5 is small, greater than 0.8 is large.
0.8 vs. rest and 0.72 vs. elliptical), unusually, this did not persist 144 hours after the marathon, which potentially indicates that this might be a false positive or that one bout of easy running was sufficient to help recovery while the second bout of easy running was sufficient to reverse any recovery that had occured. Neuromuscular performance had not recovered to baseline levels at any time point after the marathon. Again, this was contrary to their hypothesis.
What were the strengths?
— Appropriate statistics and reporting of
effect sizea quantitative measure of the magnitude of the experimental effect. Less than 0.5 is small, greater than 0.8 is large.
s (η2 and Cohen’s d).
— Included men and women.
— Clear reporting of participants training volume and frequency for running and strength. On average, they had run for 7 years, had trained 5 days per week, had run 4 previous marathons, accumulated about 63 km/week and 7 hours/wk of training, and about a ⅓ of them strength training (see Table 1 for full details).
— Intervention training sessions were supervised and load was measured with heart rate monitoring.
— Randomised, controlled trial (although it is unclear whether subjects and/or investigators and/or data analysts were blinded to trial allocation).
What were the weaknesses?
— No power calculations to justify the sample size were reported.
— No indices of marathon effort (RPE) or nutritional status (carb-intake or hydration status) were reported — these could affect recovery.
— Neither sleep, dietary intake, or physical activity levels were measured during the 192-hour post-marathon period — these could influence recovery.
— Baseline levels of blood markers of muscle damage (CK and LDH) are not reported in the paper. This is odd because the methods indicate that baseline (pre-marathon) levels were measured and included in the analysis.
— The findings are only relevant to middle-aged men with a 3 to 4 hour finish time or women with a 3.5 to 4.5 hour finish time, which, according to marathon statistics, is roughly an average marathon runner's time.
Are the findings useful in application to training/coaching practice?
Yes.
The findings emphasise what we already know, that muscle damage is elevated and neuromuscular performance is impaired after a marathon AND that these anomalies do not recover even after 192 hours (8-days). Anecdotally, anyone who has run a marathon will know that they do not feel that spring in their stride for days or even weeks afterwards. This is useful to an athlete and a coach because you should not make any plans after a marathon. Physiological, neurological, and psychological resources have been depleted — let them recover — there should be no rush to come back. My advice is to take it easy, recover with light activity, and, when you think you are ready, take another week of light activity during which you can start to make some plans.
What was the beer called?
The Padawan.
Which brewery made it?
Bierol (Tirol, Austria).
What type of beer is it?
Pale ale.
How strong is the beer (ABV)?
5.6 % ABV.
How would I describe this beer?
The Padawan has a piney and citrusy aroma, a slightly fruity/citrusy flavour, is light on the tongue and has a mildly hoppy aftertaste. A nice “sessional” beer but the force is not as strong with this one as its name might suggest.
What is my Rating of Perceived beer Enjoyment?
RP(be)E(r) = 7 out of 10.
What was the hypothesis or research question?
None. This was a review paper focused on looking at aerobic adaptations to eccentric exercise training. As a reminder, eccentric training is when muscle contracts as it is lengthening and is common in running and even more prevalent in downhill running. The rationale for this review paper is that we know eccentric exercise produces large increases in muscle strength and an ability to generate large forces even when the cardiorespiratory system is not working very hard. Thus, the focus of the review was to see if there were any improvements in the aerobic system due to eccentric training.
What did they do to test the hypothesis or answer the research question?
— This was a narrative review without any inclusion or exclusion criteria. However, 7 papers were listed in a table describing some aerobic adaptations to eccentric training.
What did they find?
— The metabolic cost of eccentric activities is about ½ to ⅓ that of a force production concentrically, with downhill running power double that of running power at a similar metabolic demand.
— Maximal heart rate can still be achieved during exhaustive eccentric exercise, but this is associated with a lower VO2max and altered ventilation dynamics.
— While not the goal of the review paper, this paper does discuss the time course of muscle damage and how repeated bouts of eccentric exercise is able to “precondition” the muscle and protect it against further eccentric bouts. Muscle damage peaks 2 days after a bout of eccentric exercise and repair continues until day 7.
— An increase in VO2 with eccentric training is not consistent in the literature and many eccentric training protocols are done using a cycle ergometer rather than downhill running and in patients with some sort of disease (heart failure, coronary artery disease, etc) rather than healthy subjects.
— When looking at mitochondrial function immediately after a bout of eccentric exercise there seems to be no consistent negative or positive effect on isolated mitochondria.
— No consistent changes to reactive oxygen species production or calcium dynamics were found in the literature.
What were the strengths?
— Excluded strength training studies that focused on eccentric work.
What were the weaknesses?
— Not a systematic review and not enough existing literature to perform a meta-analysis
— Mixture of human and animal studies to make conclusions.
Are the findings useful in application to training/coaching practice?
Not particularly. The authors argue that the use of eccentric training might benefit patients with diminished aerobic capacity to begin with. That’s not really the population that is training for a marathon or ultra race. The lack of an effect on the aerobic system is perhaps not surprising as it does feel easier to go downhill and harder downhill efforts are necessary to get normal cardiovascular changes.
What was the hypothesis or research question?
Explore the experiences of older adults conducting 3 months of training for a triathlon. This was a qualitative study rather than a quantitative study and focused on their experiences rather than the physiological adaptations that they experienced.
What did they do to test the hypothesis or answer the research question?
— They recruited 14 people (10 males, 4 females, average age 70 and 57.5 respectively) from a cohort of 25 people that had been involved in a previous study. They had never completed a triathlon before.
— Subjects completed 3 months of training, 3x per a week. Training was individualized for each subject. Training effectiveness was assessed with a 3k run, 200m swim, and 20 minute time power test on the bike.
— Subjects attended focus groups to discuss their experience training for the triathlon and completing it. They were given a list of topics prior to discussion.
— The group questions focused on 4 themes. Reason for participating in the project, own exercise background, potential lifestyle changes due to their participation, their introduction to triathlon.
— Interviews were analyzed using techniques common to qualitative research which included; generating codes, searching for themes, defining and naming themes, and producing a report and examples of those themes.
What did they find?
— The subjects improved their measures of fitness and
— The overall theme that the researchers identified was well-being and being fit. Subthemes were motivation, progress and coping and breaking barriers (see Figure below).
— Within motivation the sub themes of enjoyment of the sport, social community, and quality and relaxation emerged as themes with supporting quotes such as ““Always liked the context of exercising, the social setting of doing sports.” and “Probably did not have enough willpower to do
this alone.”
— Coping was also another major theme with sub themes of learning, taken care of and going from panic to proficiency. Participants genuinely enjoyed learning in an environment that they were taken care of and going from being scared of a particular activity to becoming proficient to feel safe and/or skilled at that aspect of triathlons. “Fun to have so much progress in all training sessions.” “Was so afraid of the swimming in the sea, but now I am no longer afraid of doing it so often I can.”
— The last main theme was breaking barriers, which had subthemes of understanding and knowledge, achieving a goal, and endorphin kick from exercise. “Important for me to show that even if one turns 70–80 years old, life is not over.” “I have become addicted to endorphin intoxication after training sessions.”
What were the strengths?
— All subjects completed the training and competition and thus are considered knowledgeable in the subject area..
— Fairley homogenous sample and sufficient number of subjects which allow sufficient evidence to address the research objective.
What were the weaknesses?
— Translated quotes from Norwegian to English. .
— Fairley homogenous sample
— Discussions were led by a much younger researcher.
— Self selection of the subjects into the event and subjects that were already familiar with a research setting.
Are the findings useful in application to training/coaching practice?
When working with older adults there are different challenges than working with younger adults. This paper identifies some of the factors that allowed older adults to succeed. Specifically, the individual training allowed the subjects to obtain a level of mastery over the different aspects of triathlon which they did not possess when starting training. Given the short time frame and novice abilities of the subjects these findings may not be the same for older adults who have trained for a long time and already developed a sense of mastery over their discipline. Regardless, coaches can help athletes create and become a part of the community, overcome fears, and set goals specific for their age which will lead to increased overall well-being and participation by older athletes.
What was the beer called?
Reclusa
Which brewery made it?
Fort George Brewery. Astoria, OR. United States
What type of beer is it?
The final decision was 57.1% rye chocolate stout aged in Four Roses bourbon barrels, 14.3% buckwheat walnut stout aged in Four Roses bourbon barrels, 14.3% oatmeal stout aged in House Spirits Westward whiskey barrels, and 14.3% English barleywine aged in Adelsheim Pinot Noir barrels and finished in Bull Run bourbon barrels.
How strong is the beer (ABV)?
13 % ABV.
How would I describe this beer?
The combination of barrels used to age this stout smooth out the flavor profile while providing a richness worthy of dessert. It's boozy, but you still get dark cherry and plum to come through as well. Enjoyable.
What is my Rating of Perceived beer Enjoyment?
RP(be)E(r) = 8 out of 10.
That is all for this month's nerd alert. We hope to have succeeded in helping you learn a little more about the developments in the world of running science. If not, we hope you enjoyed a nice beer…
Until next month, stay nerdy and keep training smart.
Everyday is a school day.
Empower yourself to train smart.
Think critically. Be informed. Stay educated.
Disclaimer: We occasionally mention brands and products but it is important to know that we are not sponsored by or receiving advertisement royalties from anyone. We have conducted biomedical research for which we have received research money from publicly-funded national research councils and medical charities, and also from private companies. We have also advised private companies on their product developments. These companies had no control over the research design, data analysis, or publication outcomes of our work. Any recommendations we make are, and always will be, based on our own views and opinions shaped by the evidence available. The information we provide is not medical advice. Before making any changes to your habits of daily living based on any information we provide, always ensure it is safe for you to do so and consult your doctor if you are unsure.
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About the authors:
Matt and Thomas are both passionate about making science accessible and helping folks meet their fitness and performance goals. They both have PhDs in exercise science, are widely published, have had their own athletic careers, and are both performance coaches alongside their day jobs. Originally from different sides of the Atlantic, their paths first crossed in Copenhagen in 2010 as research scientists at the Centre for Inflammation and Metabolism at Rigshospitalet (Copenhagen University Hospital). After discussing lots of science, spending many a mile pounding the trails, and frequent micro brew pub drinking sessions, they became firm friends. Thomas even got a "buy one get one free" deal out of the friendship, marrying one of Matt's best friends from home after a chance encounter during a training weekend for the CCC in Schwartzwald. Although they are once again separated by the Atlantic, Matt and Thomas meet up about once a year and have weekly video chats about science, running, and beer. This "nerd alert" was created as an outlet for some of the hundreds of scientific papers they read each month.
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and Matt Laye PhD 
What was the hypothesis or research question?
Buy me a beer.
