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.
Share this nerd alert:
Click the title of each article to "drop-down" the summary.
What was the hypothesis or research question?
The authors aimed to determine the effects of treadmill exercise duration at different intensities on
both overall and differentiated session-RPE among recreationally active participants. Since physiological parameters and RPE increase during constant speed submaximal running in an intensity-dependent manner, the authors hypothesized that running duration would influence session-RPE but only after more intense running bouts.
What did they do to test the hypothesis or answer the research question?
— 16 recreationally-active (but untrained) males were included in a study using a randomized crossover within-subjects design.
— All participants completed 3 treadmill speeds (“weak”, “moderate”, and “strong”) for 15 and 30 minutes, and participants reported 3 different types of session-RPE (overall, breathing, and legs).
— Participants completed the 9 tests separated by 48 to 72 hours, completing the whole protocol within 3-4 weeks.
What did they find?
— Significant increases in session-RPE were found with increases in running speed (P<0.01,
eta-squared [η2]a type of effect size that is analogous to R-squared from regression and indicates the amount of variation explained by the predictor variable in the total variation for the outcome variable. An eta-squared of 0.01 is a small effect, 0.06 is medium, and 0.14 is a large effect.
= 0.48 aka a large effect) and duration (P<0.01, η2 = 0.16, a large effect) with a significant speed x duration interaction (P<0.01, η2 = 0.10, a moderate effect).
— There was a significant effect for session-RPE type (P=0.01, η2 = 0.05, small effect) where overall session-RPE was lower than Legs session-RPE and higher than Breathing session-RPE.
— Changes in session-RPE from 15 to 30-minute trials were minimal for the slow speed/“weak” session-RPE (
Cohen’s da type of effect size that quantities the average change score relative to the standard deviation (i.e. the range) of the change scores.
= 0.04 to 0.25, negligible to small effect) but got higher at “moderate” (Cohen’s d = 0.88 to 1.06, large effect) and “strong” (Cohen’s d = 1.94 to 2.50, huge effect) speeds and sRPEs.
— The authors concluded that exercise duration affects session-RPE in an intensity dependent manner. Specifically, recreationally active folks report increasing higher RPE values during a short run (up to 30-mins), especially at higher intensities.
What were the strengths?
— Crossover design (all subjects did all trials).
— Counterbalanced design (the order of trials and the order of speeds were randomised).
—
Effect sizesa quantitative measure of the magnitude of the experimental effect. Less than 0.2 is no effect, 0.2 to 0.5 is small, 0.5 to 0.8 is moderate, greater than 0.8 is large.
were calculated (using
eta-squared (η2)a type of effect size that is analogous to R-squared from regression and indicates the amount of variation explained by the predictor variable in the total variation for the outcome variable. An eta-squared of 0.01 is a small effect, 0.06 is medium, and 0.14 is a large effect.
and
Cohen’s da type of effect size that quantities the average change score relative to the standard deviation (i.e. the range) of the change scores.
) and, in the author’s words, “to enable future comparisons between studies and meta-analyses” — this is awesome!
What were the weaknesses?
— Only males were studied.
— The participants were not endurance trained so the findings are hard to extrapolate to athletes.
— It is not entirely clear what “weak”, “moderate”, and “strong” speeds are equivalent to. The authors report that they were “determined from the graded exercise test” and that they “were suggested as perceptual references for light, moderate and vigorous exercise categories” at RPE 2/10 (weak), 3/10 (moderate), and 5/10 (strong). If I was designing the study, I would have used 3 speeds that put subjects in one of the 3 biological intensity domains: easy (less than their first ventilatory threshold, VT1), moderate (between VT1 and VT2), and heavy (above their second ventilatory threshold, VT2).
Are the findings useful in application to training/coaching practice?
Yes and no.
Since the paper only studied males and only untrained recreationally active but untrained men, we cannot extrapolate the findings to females or endurance-trained athletes. Also, since the intensity of running was only pushed up to RPE 5/10 we also cannot know what might happen during sessions where an athlete might run for prolonged periods at RPE of 6 to 8/10 or even do intervals at RPE 8-9/10.
Nonetheless, “RPE drift” is an important phenomenon for all athletes and coaches to be aware of during training prescription and during sessions. I use RPE in my coaching and in my own training and aim to advise my athletes to use RPE as a guide but not a rule and in doing so I prescribe “maximum” RPE values to drift to during a session. For example, I prescribe an Easy run as RPE 2 to 4 out of 10 and to step off the gas if RPE exceeds 4/10.
What was the hypothesis or research question?
The authors aimed to determine the effect of sex on the efficacy of intermittent post-exercise sauna bathing to induce heat acclimation and improve markers of temperate exercise performance in trained athletes. The authors hypothesised that repeated post-exercise sauna bathing would be more effective in males for inducing desirable adaptations during both exercise-heat stress and temperate exercise.
What did they do to test the hypothesis or answer the research question?
— Twenty-six (16 female, 10 male) college-aged trained runners (V̇O2max female 52.6 ± 6.9 and male 64.6 ± 2.4 mL/kg/min) were included in a randomised controlled trial design.
— Subjects performed V̇O2max and lactate profile tests in temperate conditions (18°C) and a “heat tolerance test” (a 30 min run at 9 kph at 2% gradient) in 40°C and 40% relative humidity.
— All tests were completed before and after 3-weeks of runners’ “normal” training alone (Control group) or in addition to ~30-mins of post-exercise sauna bathing (in 101–108°C) ~3 times per week (Sauna group).
Schematic of the experimental design. Females and males in the intermittent post-exercise sauna bathing intervention group (SAUNA) and control group (CON) completed temperate exercise tests (18 °C) consisting of lactate profile (LP) and maximal aerobic capacity (V̇O2max) tests, a running heat tolerance test (HTT; 30 min, 9 km·h−1/2% gradient, 40 °C/40%RH), and a plasma volume assessment at baseline (Pre) and following three weeks (Post) of sauna intervention or control. Respective tests were completed ~ 28 days apart. Black bars indicate weeks. Figure available as Open-access at https://doi.org/10.1186/s40798-021-00342-6
What did they find?
— Following the intervention, females and males exhibited similar statistically-significant reductions in peak rectal temperature, skin temperature, and heart rate during the running heat tolerance test. During the exercise heat stress stress, females reported higher RPE than the males at baseline but not after the intervention.
— In the sauna group, females reported higher thermal sensation and less thermal comfort ratings (i.e. they reported being hotter and less comfortable) than males. But, females and males reported similar reductions in peak thermal sensation and peak thermal comfort.
— Females and males showed similar statistically-significant improvements in V̇O2max and running speed at 4 mmol/L blood lactate concentration.
— The data suggest that heat acclimation using post-exercise sauna occurs via different mechanisms: only females exhibited an increase in active sweat glands on the forearm (measured via modified iodine technique) while only males increased forearm blood flow (measured via venous occlusion plethysmography).
— The authors concluded that 3-weeks of post-exercise sauna bathing induces heat acclimation in females and males and is an effective ergogenic aid for both sexes.
What were the strengths?
— Studying both males and females to examine potential sex differences but also to add needed data in females, which is lacking in may areas of clinical physiology.
— Ecologically-valid nature of the intervention (adding the heat acclimation intervention to the athletes’ habitual training).
— Studying trained endurance runners.
— Highly comprehensive evaluation of useful variables that an athlete and coach might find relevant in the real world setting.
What were the weaknesses?
— Although there is a thorough breakdown of athletes’ training during the study, we have no idea whether training load or type during the study changed in comparison to before the study. Therefore, it is impossible to have confidence in the authors’ conclusion that “Post-exercise sauna bathing is also an effective ergogenic aid for both sexes.”.
— Despite not measuring participants' iron status (e.g. plasma ferritin levels) before, during, or after the interventions, the authors chose to supplement all athletes with 65 mg of daily ferrous sulphate, starting 2-weeks before the athlete’s intervention until study completion. There is, therefore, a potential (and completely unknowable) role of changes in iron status on the study outcomes.
— Since the study was conducted in the UK, it is safe to assume that participants were not heat acclimated prior to the study. However, we are not told which time of year the study took place; even the UK gets warm in the summer.
— Although
effect sizesa quantitative measure of the magnitude of the experimental effect. Less than 0.2 is no effect, 0.2 to 0.5 is small, 0.5 to 0.8 is moderate, greater than 0.8 is large.
from previous studies were used for power calculations to justify the chosen sample size, the authors did not compute
effect sizesa quantitative measure of the magnitude of the experimental effect. Less than 0.2 is no effect, 0.2 to 0.5 is small, 0.5 to 0.8 is moderate, greater than 0.8 is large.
for their own observations.
Are the findings useful in application to training/coaching practice?
Yes.
30-minutes of post-running sauna 3x/wk helped lower heat stress and cardiovascular strain when running in very hot conditions. Therefore, if heat acclimation is something you or your athletes might need in prep for an upcoming event, a regular post-exercise sauna might be one useful approach to add to your toolbox. (NOTE: I have an article series on training and racing in the heat coming out soon).
What was the hypothesis or research question?
The authors aimed to determine the effect of trail-running race distance on neuromuscular function and fatigability and corticospinal excitability. They hypothesized that reduced neuromuscular function, particularly within the central nervous system, would be greater for longer races.
What did they do to test the hypothesis or answer the research question?
— Forty-six healthy trained (VO2max 61.7 ± 11.2) and experienced male ultra-endurance trail runners were recruited but only 32 completed the races (at the UTMB week) and pre/post testing.
— Participants were divided into “long” (longer than 100 km; competing in UTMB, TDS, or CCC) and “short” (shorter than 60 km; competing in MCC or OCC) groups.
— To assess voluntary activation and muscle contractile properties of knee-extensor (quad) and plantar-flexor (calf) muscles, before and after the races, maximal voluntary contraction (MVC) torque and evoked responses to electrical nerve stimulation during MVCs and at rest were measured.
— And, to assess evoked responses and corticospinal excitability in maximal and submaximal knee-extensor contractions, transcranial magnetic stimulation (TMS) was used.
What did they find?
— Runners’ blood levels of CRP (C-reactive protein) and CK (creatine kinase) were far higher after the “long” races than the “short” races, indicative of greater whole-body inflammation (CRP) and muscle damage (CK) after the longer races.
— Maximal voluntary activation decreased similarly in “Long” and “short” races in both muscle groups.
— There were no differences between “Long” and “short” races for plantar-flexor (calf) muscles MVC or twitch torque and plantar-flexor muscles fatigability was unaffected by race distance.
— Race distance significantly (
Pthe probability that the effect could be explained by random chance
≤0.003) correlated with knee-extensor (quad) muscle MVC (
correlation coefficientthe strength (effect size) of a relationship (correlation) between two variables, where less than 0.1 (or -0.1) indicates no relationship, (-)0.1 to (-)0.3 indicates a small relationship, (-)0.3 to (-)0.5 a moderate relationship, and greater than (-)0.5 is large.
= −0.556) and twitch (
correlation coefficientthe strength (effect size) of a relationship (correlation) between two variables, where less than 0.1 (or -0.1) indicates no relationship, (-)0.1 to (-)0.3 indicates a small relationship, (-)0.3 to (-)0.5 a moderate relationship, and greater than (-)0.5 is large.
= −0.521) torque decreases — i.e. longer race = more fatigue.
— Knee-extensor (quad) muscle twitch torque decreased more in “Long” (−28 ± 14%) than “short” races (−14 ± 10%, P=0.005); however, knee-extensor (quad) muscle MVC time × distance interaction was not significant (P=0.073).
— The transcranial magnetic stimulation-elicited silent period decreased in “long” (P=0.021) but not “short” (P=0.912) races, suggesting a reduction in cortical inhibition during longer trail races — prompting the question “does our brain “let the brakes off” later into a long race?”.
What were the strengths?
— Ecologically-valid “in the field” observational study.
— Effect sizes were reported (but only for statistically-significant findings, which somewhat defeats the point of an effect size).
What were the weaknesses?
— No female athletes were studied.
— We don’t know whether the outcomes were correlated with finish time or finish position.
— No info is given regarding the factors that may cause fatigue during ultra running, e.g. elevated body temp, low blood glucose, low glycogen, low hydration status, etc. We also have no idea what athletes ate during the race.
Are the findings useful in application to training/coaching practice?
No.
The data do not provide new knowledge. The work simply adds to the multiple studies this group has done at UTMB showing that ultra trail races cause neuromuscular fatigue and that longer races = more fatigue. Without coupling measures of neuromuscular fatigue with a thorough evaluation of athletes’ during-race habits (feeding/hydrating/cooling strategies), it is difficult to know what is causing these observations. What coaches and athletes really need is data on how neuromuscular fatigue can be “resisted” for as long as possible during an ultra trail race.
What was the hypothesis or research question?
Increased fatigue associated with increasing exercise intensity or duration leads to an impairment of limb coordination and movement skill. The link between the physiological aspects of fatigue and the neural response to fatigue are not well known. This paper attempted to describe the relationship between increasing exercise intensity and neural responses using electroencephalography (EEG) to characterize resting signal networks (RSN) in the brain. These RSNs represent a broader look at how different parts of the brain are connected to one another and have been linked to attention-related and sensorimotor brain activity, both of which may be important for sport performance.
What did they do to test the hypothesis or answer the research question?
— 16 healthy male subjects (VO2max = 51.6 mL/min/kg) underwent 3 different treadmill tests. 10 minutes at 50% of velocity at VO2max (vVO2max), 10 minutes at 70% of vVO2max, and for as long as possible at 90% of vVO2max.
Experimental protocol. Participants performed 4 running stages at 50%, 70%, 90% and 50% of their individual speed at peak oxygen uptake assessed during the ramp protocol. At six different timepoints (PRE, ACUTE1, ACUTE2, ACUTE3, REG1 and REG2), electroencephalography (EEG) resting state in sitting position was recorded over 5 min. Further, resting heart rate over 5 min in sitting position (HR), blood lactate sample from the earlobe (BLa) and rate of perceived exertion (RPE) were assessed.
Figure available as Open-access at https://doi.org/10.1007/s00421-021-04712-6
— To characterize the RSN they used EEG rather than the preferred, but more expensive and more difficult functional MRI approach. To use EEG they developed an analysis which clustered the various signals from the 64 channels of measurements into several metrics that are combined to create a metric called small world index (SWI) (which is the ratio of clustering coefficient and path length for those interested; full details in Table 2 ). Specifically, the SWI was calculated for three frequency bands, theta, alpha-1 and alpha-2. SWI indicates an efficient brain network where a low SWI is less efficient and more prevalent in diseases like Alzheimers.
What did they find?
— The major finding was that as exercise intensity increased the RSN in the theta frequency of theta brain waves was decreased. Theta brain waves are linked to prefrontal cortex activity and attentional activity. Interestingly the theta brain waves became less highly correlated indicating a brain disturbance during exhaustive exercise.
— Other regional parts of the brain showed changes in alpha wave activity, but when looked at as a RSN there was no specific effect of the exhaustive exercise.
What were the strengths?
— Given my own lack of knowledge about how EEGs work and the analysis specifically it is hard to confidently give a list of methodological strengths and weaknesses. However….
— EEGs are a lot easier to perform than fMRI or other brain activity measures.
What were the weaknesses?
— Why were females not included in this study?
— Could each of the exercise intensities be studied on a different day to prevent the accumulation of fatigue from potentially contributing to many of the differences.
— The brian network described predicts a specific behavioral change (lack of motor skill) and yet no behavioral changes were measured.
— EEGs do not directly measure brain activity and instead measure all electrical activity which is prone to interferences from non-neuronal sources.
Are the findings useful in application to training/coaching practice?
Not really. Companies will likely develop a brain wave measure that might give athletes insight into their readiness, but currently those do not exist and this paper does not suggest they will be overly useful from a day to day training perspective. An example is that most athletes know when they are tired during a training session and they know that they are less capable of doing hard work at that point. We don’t need a fancy gadget to tell us that. It seems a stretch to say that future work would help coaches manage athletes' load to a better degree than existing tools given the limited scope of this study.
What was the hypothesis or research question?
Psychological aspects play an important role in pain management. The biopsychosocial theory of pain management suggests that perceived pain and pain intensity are dependent upon a complex interaction between biological - psychological - social aspects. However, most treatments for pain neglect the social and psychological aspects of pain. This study aimed to add psychological treatment to physical treatment to see if there were additional benefits to effectiveness and perceived effectiveness of treatment. Typically injured athletes will dwell or become hyper aware of injuries, a phenomenon called catastrophizing. Conversely, mindfulness is a psychological practice that helps people focus on the current moment without judgement and therefore without catastrophizing. The authors specifically looked at patellofemoral pain (PFP) in female recreational runners and hypothesized “that compared with a control group, runners with patellofemoral pain who received mindfulness training in addition to the exercise treatment program would experience (1) less pain intensity, fear of reinjury, and pain catastrophizing; and (2) better knee function and more frequent use of coping strategies to manage pain”.
What did they do to test the hypothesis or answer the research question?
— 30 females between the ages of 18 - 40, running at least 2 x week (45 minutes/run), having patellofemoral pain, a reduced capacity to do everyday tasks, and persistent pain on several tasks were recruited for the study. Runners with other causes of knee pain were excluded.
— Subjects were randomized to either 18 weeks of exercise therapy or 18 weeks of exercise therapy + mindfulness 8 weeks, 4 weeks prior to exercise therapy and 4 weeks overlapping with the exercise therapy. Measurements were taken at baseline, 9 weeks, 18 weeks, and 2 months after conclusion of the intervention. Subjects were allowed to keep training, but asked to reduce running volume and prevent a pain level above 3/10. The exercise therapy consisted of 13 exercises that would take between 60-90 minutes per a session, done 3 x week and was based on previous exercise protocols that had successfully reduced patellofemoral pain in runners. The mindfulness training was done in 2 sessions in groups and then continued by the individuals for 45 minutes/day. The mindfulness was typical of that type of training and included breath work, body scans, sitting and walking meditations.
— The main outcomes of the study were as follows. A visual analog scale (VAS) of pain, a survey of knee symptoms and pain in daily life, survey of perceived effectiveness of treatment, fear of movement and reinjury, a survey of pain catastrophizing, and a survey of coping strategies.
What did they find?
— Usual pain, pain during stepping, pain during running all were reduced to a greater degree in the meditation + exercise group through the 18 weeks of intervention and at a 2 month follow up. Both groups showed large improvements (
effect sizea quantitative measure of the magnitude of the experimental effect. Less than 0.2 is no effect, 0.2 to 0.5 is small, 0.5 to 0.8 is moderate, greater than 0.8 is large.
= ~1.12 to 2), but the meditation-exercise group showed a significant and slightly better (13 - 17%) reduction in pain.
— Knee related pain and perceived effectiveness of the treatment were superior in the meditation + exercise group relative to the exercise only group (14.8% and 20% better). Both groups also improved in these metrics.
— Fear of movement, coping strategies, and pain catastrophizing were all about 30% lower in the meditation-exercise group compared to the exercise group. Fear of movement was not improved in the exercise alone group.
— The improvements in the meditation-exercise group appeared at the first time point (9 weeks) and persisted or even became greater by the follow up 2 months after the intervention ended.
What were the strengths?
— Well matched, provided power calculations.
— Provided overall
effect sizea quantitative measure of the magnitude of the experimental effect. Less than 0.2 is no effect, 0.2 to 0.5 is small, 0.5 to 0.8 is moderate, greater than 0.8 is large.
measurements.
— Post-intervention time point to see whether the effects were maintained.
What were the weaknesses?
— All data were subjective, not objective measures of whether pain or function were improved.
— No
effect sizea quantitative measure of the magnitude of the experimental effect. Less than 0.2 is no effect, 0.2 to 0.5 is small, 0.5 to 0.8 is moderate, greater than 0.8 is large.
s for between the group measures.
— Mindfulness program not well described and the actual adherence was not measured.
— Group classes may have added a social component which could confound the results.
— May have had selection bias. A lot of subjects were not included.
Are the findings useful in application to training/coaching practice?
Absolutely. The bio-psychological-social model of injury makes a lot of sense and yet we mostly focus on the biological role of injuries (guilty as charged personally). Spending even a fraction of the time focusing on different aspects of pain perception seems appropriate given that placebos and sham surgeries also are effective treatment for some injuries. Any athlete with an injury should consider mindfulness practice to add to their physical exercises. A well developed mindfulness program specifically for injured runners might be really useful.
What was the
beerLiquid joy. The thing you drink when you don’t train.
called?
Live Transmission.
Which brewery made it?
Flying Monkeys Craft Brewery (Barrie, Ontario, Canada).
What type of
beerLiquid joy. The thing you drink when you don’t train.
is it?
Milkshake IPA.
How strong is the
beerLiquid joy. The thing you drink when you don’t train.
?
6.3% ABV.
How would I describe this
beerLiquid joy. The thing you drink when you don’t train.
?
Gentle milky aroma and incredibly jazzy on the tongue with plenty of mouth feel. Smooth, creamy, and milkshakey as it flows down the tubes… Then… wait… for the subtle coconuts to smash your taste buds into submission. Amazing. But, this was a special month for beer, because Matt and I got to dazzle our taste buds in-person for the first time in over 2-years!
What is my Rating of Perceived Beer Enjoyment?
RP(be)E(r) = 9 out of 10.
What was the
beerLiquid joy. The thing you drink when you don’t train.
called?
Dobbelt Bittert
Which brewery made it?
Herslev Bryghus (Denmark)
What type of
beerLiquid joy. The thing you drink when you don’t train.
is it?
Low alcohol IPA.
How strong is the
beerLiquid joy. The thing you drink when you don’t train.
?
2% ABV.
How would I describe this
beerLiquid joy. The thing you drink when you don’t train.
?
I’ve taken to drinking some zero or low alcohol beers during my stay in Denmark. There are a lot of choices in that category. This particular beer is a light straw color, lighter than a typical IPA. It tastes like a normal beer, which is a plus, but it tastes like a fairly average beer which is a minus. Fairly bitter as the name suggests and could use a malty back end to balance the bitterness and provide a little more richness and body to the beer. Simcoe hops, oats and wheat malt backbone.
What is my Rating of Perceived Beer Enjoyment?
RP(be)E(r) = 6 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.
If you find value in these nerd-alerts, please help keep them alive and buy us a beer:
If you enjoy this free content, please like and follow @veohtu, @mjlaye and @thomaspjsolomon and share these posts on your social media pages.
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.
To read more about the authors, click the buttons:
and Matt Laye PhD 
What was the hypothesis or research question?
Buy me a beer.
