RESEARCH: Studies shared from 16 to 22 Jan 2023

All the studies I've shared are available on the RESOURCES PAGE.

This weekly summary is also available in my Substack newsletter - Endurance: Ideas + Implementation.

This week's quick summary:

  • muscle cramping in the marathon
  • sodium bicarbonate acutely improves muscular endurance
  • the wisdom of not knowing
  • GI distress and ergogenicity of sodium bicarbonate
  • low FODMAP diet to reduce exercise-related GI symptoms

PHYSIOLOGY: Muscle cramping in the marathon: Dehydration and electrolyte depletion vs. muscle damage


  1. Our aim was to compare dehydration variables, serum electrolytes, and muscle damage serum markers between runners who suffered exercise-associated muscle cramps (EAMC) and runners who did not suffer EAMC in a road marathon.
  2. Before and after the race, blood and urine samples were collected and body mass (BM) was measured.
  3. Immediately after the race EAMC were diagnosed.
  4. Body mass change, post-race urine specific gravity, and serum sodium and potassium concentrations were not different between crampers and noncrampers.
  5. Conversely, runners who suffered EAMC exhibited significantly greater post-race creatine kinase and lactate dehydrogenase.
  6. Therefore, runners who suffered EAMC did not exhibit a greater degree of dehydration and electrolyte depletion after the marathon but displayed significantly higher concentrations of muscle damage biomarkers.


According to this study cramping does not appear to be the result of dehydration or electrolyte depletion. Athletes who suffer from cramps should therefore look for other causes such as inadequate training or poor pacing.
When I shared this on Twitter there were a lot of comments as cramping appears to affect many people. Here are some of the additional resources that were mentioned to explore in the search for resolving cramps:

SUPPLEMENT: Effects of sodium bicarbonate supplementation on muscular strength and endurance

Last week I shared a study showing that capsaicin could be beneficial for muscular endurance. Previously I've shared studies showing that sodium bicarbonate can may be beneficial for sprint performance at the end of an endurance race and that a continuous warm-up optimizes levels in the blood. In this meta-analysis the authors looked at sodium bicarbonate for muscular strength which could suggest its potential use as an alternative to capsaicin (or as a complement?).


  1. The effects of sodium bicarbonate on muscular strength and muscular endurance are commonly acknowledged as unclear due to the contrasting evidence on the topic.
  2. Thirteen studies explored the effects of sodium bicarbonate on muscular endurance and eleven on muscular strength.
  3. Sodium bicarbonate supplementation was found to be ergogenic for muscular endurance.
  4. The performance-enhancing effects of sodium bicarbonate were significant for both small and large muscle groups.
  5. Sodium bicarbonate ingestion was not found to enhance muscular strength.
  6. Overall, sodium bicarbonate supplementation acutely improves muscular endurance of small and large muscle groups.


Sodium bicarbonate may be a useful supplement to aid in muscular endurance training. The doses that I have seen in previous studies have been between 150mg/kg and 300mg/kg body weight ingested prior to exercise.

Whenever I share a study about sodium bicarbonate I receive many replies that it can cause gastointestinal issues. Therefore, I would suggest that this is a supplement that needs to be thoroughly tested in training before considering using it in a race situation.

PSYCHOLOGY: On the wisdom of not-knowing: reflections of an Olympic Canoe Slalom coach


  1. Never has the domain of sports coaching been so inundated with secondary information.
  2. Here, we question whether such detailed secondary information has led us to know too much, obscuring what the world has to share directly with us.
  3. To over-rely on secondary information is to narrow in on certainty, on cause-effects that are oft-espoused through de-contextualised ‘performance’ tests and metrics. This indirect approach eschews opening up to uncertainty, to ongoing inquiry embedded in primary experience.
  4. In presenting this thesis, we hope to encourage others – in sports coaching and beyond – to embrace an ethos of not-knowing, opening up to the ‘goings on’ of what interests them, actively attending and directly responding with genuine care and curiosity.
  5. The accompanying growth of responsiveness to one’s surroundings emerges from listening to what it has share, joining in conversation to find ways of carrying on.
  6. It is in this responsiveness, we contend, that a wisdom can be found; a wisdom of not-knowing.


This paper looked specifically at the domain of secondary information for coaches, but it could apply equally to athletes. It is important to ensure the context for assessing training data and metrics helps to create a robust and rich picture of the athletes current status. Relying on metrics alone can be deceptive and hide some of the nuance that comes from the complex nature of the human body.
A useful means of structuring high intensity training sessions in a microcycle is to have some quantititave sessions (with pace or power goals) and some qualitative sessions (with RPE or perceptual goals). This way the athlete still keeps track of their progress in quantitative sessions, but can also tune in to sensations during the qualitative sessions.

SUPPLEMENT: Sodium Bicarbonate and High-Intensity-Cycling Capacity

This study is a useful addition to the study on sodium bicarbonate above, as it looks into the variability of responses by athletes. The objective was addressing the question of gastro-intenstinal issues that can occur when using sodium bicarbonate.


  1. To determine whether gastrointestinal (GI) distress affects the ergogenicity of sodium bicarbonate and whether the degree of alkalemia or other metabolic responses is different between individuals who improve exercise capacity and those who do not.
  2. Participants were supplemented with 0.3 g/kg body mass of either placebo (maltodextrin) or sodium bicarbonate (SB).
  3. SB supplementation did not significantly increase total work done, although magnitude-based inferences suggested a 63% likelihood of a positive effect.
  4. When data were analyzed without 4 participants who experienced GI discomfort, TWD was significantly improved with SB.
  5. There were also differences in the preexercise-to-postexercise change in blood pH, bicarbonate, and base excess between individuals who improved and those who did not.
  6. SB improved high-intensity-cycling capacity but only with the exclusion of participants experiencing GI discomfort.


This study reflects the experience of many of the athletes who I've heard from about using sodium bicarbonate: if it works for you then it is ergogenic, but it can give athletes severe GI issues and have very negative impacts on performance. If this is a supplement an athlete wants to try, I would make sure they do multiple trials at race pace without any GI issues before considering using it prior to or during a race.
Two people shared with me their experiences with sodium bicarbonate on Twitter:

NUTRITION: Effect of a short-term low fermentable oligiosaccharide, disaccharide, monosaccharide and polyol (FODMAP) diet on exercise


  1. Research has demonstrated that low fermentable oligiosaccharide, disaccharide, monosaccharide and polyol (FODMAP) diets improve gastrointestinal (GI) symptoms in irritable bowel syndrome sufferers.
  2. Exercise-related GI issues are a common cause of underperformance, with current evidence focusing on the use of FODMAP approaches with recreationally competitive or highly trained athletes.
  3. Sixteen healthy volunteers were randomly assigned in a crossover design manner to either a LOW-FODMAP or HIGH FODMAP diet for 7 days, with a one week washout period followed by a further 7 days on the alternate diet.
  4. Perceived ability to exercise (frequency, intensity and duration) in relation to each dietary period was also rated using a visual analogue scale.
  5. Overall IBS-SSS score significantly reduced in the LOW-FODMAP condition from 81.1 to 31.3 (arbitrary units).
  6. A short-term LOW-FODMAP diet under free-living conditions reduced exercise-related GI symptoms and improved the perceived ability to exercise in otherwise healthy, recreational runners.


Athletes who struggle with GI issues during a race could benefit from testing a low FODMAP diet in race week to see if it can alleviate those symptoms.

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