RESEARCH: studies shared from 17 to 23 Apr 23

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



This week's quick summary:

  • Psychological stress and anxiety and gastrointestinal symptoms
  • Substance use in a mountain ultramarathon
  • Muscle blood flow and dehydration
  • Variability of running economy using different shoes
  • Manual therapy and pneumatic compression for recovery


PSYCHOLOGY: The relationship between psychological stress and anxiety with gastrointestinal symptoms before and during a 56 km ultramarathon running race

Gastrointestinal issues are one of the most common reasons for DNFs or poor performance in ultramarathons. Higher carbohydrate intakes are associated with faster times, which is a good reason to increase CHO intake, but also with higher occurence of GI issues. Sleep the night before a race is also associated with GI issues and there appears to be some reduction in the symptoms when controlling for anxiety. This study looked specifically at anxiety and "assessed relationships and sex differences between psychological state (recovery, stress, anxiety, and self-confidence) and gastrointestinal symptoms (GIS) prior to and during a 56 km ultramarathon running race and identified predictive factors of race GIS".

STUDY DETAILS

  1. Forty-four (26 males, 18 females) ultramarathon competitors completed anxiety, recovery, stress and GIS questionnaires for three days prior to the race and immediately pre-race.
  2. Race GIS were assessed immediately post-race.
  3. Race GIS were significantly correlated with recovery, stress, and anxiety, calculated as the mean of the three days preceding the race and on race morning.
  4. The correlation between anxiety and GIS was strongest in the 24 h immediately prior to the race.
  5. There were no sex differences in the number and severity of GIS leading up to or during the race, however, females reported greater state anxiety and lower self-confidence than males over the three days preceding the race and on race morning.
  6. Endurance athletes that experience GIS during competition should investigate elevated stress and/or anxiety as a potential contributor and identify if management strategies can reduce the occurrence and severity of GIS.

PRACTICAL TAKEAWAY

The causes of GI issues are not easy to diagnose as the "etiology of gastrointestinal symptoms during endurance exercise is multi-factorial". This study is useful in that it provides another potential cause of GI issues that can be included in analysis and that could potentially help in identifying and reducing GI issues in ultramarathons. My recommendation for athletes struggling with stomach issues is to read the book "The Athlete's Gut" by Dr Patrick Wilson as he provides useful insight into gut function including a section on stress and anxiety.


SUPPLEMENT: Substance use and misuse in a mountain ultramarathon

A previous study I shared estimate that up to 75% of runners in an ultramarathon use non-steroidal antiinflammatory drugs (NSAIDs) during competition, but these had no influence on physical performance. This study adds to that knowledge by exploring "the use of medication among endurance runners participating in the 2014 Infernal Trail des Vosges".

STUDY DETAILS

  1. Among the 389 runners engaged, 297 (76.3%) completed a specific questionnaire dealing with substance use/misuse.
  2. Our results show a 27% (before the race) and 18% (during the race) prevalence of substance use.
  3. The two major classes of substances used were non-steroidal anti-inflammatory drugs (NSAIDs; 9.8%) and painkillers (6.7%), principally because of osteo-articular pain (29.6%) or to prevent pain (28.2%).
  4. Our results could be explained by the specific characteristics of ultrarunners predominantly motivated by personal achievement and general health (recreational approach).

PRACTICAL TAKEAWAY

This study suggests a lower use of substances during a race which is good news. My recommendation in this case is simple: do not use NSAIDs (such as ibuprofen) during an ultramarathon.


HYDRATION: Muscle blood flow is reduced with dehydration during prolonged exercise in humans

I have shared a range of different studies on hydration (search for "hydration" on my resources page) with results showing a range of outcomes: limited impact of dehydration on performance, an impact on cognitive function, and the impacts on thermoregulation. This study interested me because it looked into whether or not "the blood flow to exercising muscles becomes reduced when cardiac output and systemic vascular conductance decline with dehydration during prolonged exercise in the heat".

STUDY DETAILS

  1. Seven euhydrated, endurance-trained cyclists performed two bicycle exercise trials in the heat (35 C; 40-50 % relative humidity; 61 +/- 2 % of maximal VO2), separated by 1 week.
  2. During the first trial (dehydration trial, DE), they bicycled until volitional exhaustion (135min, while developing progressive dehydration and hyperthermia (3.9% body weight loss).
  3. In the second trial (control trial), they bicycled for the same period of time while maintaining euhydration by ingesting fluids.
  4. During the 20 min-exhaustion period of DE, cardiac output, LBF and systemic vascular conductance declined significantly yet muscle vascular conductance was unaltered.
  5. In contrast, during the same period of control, all these cardiovascular variables tended to increase.
  6. After 135min of DE, the lower blood flow to the exercising legs accounted for approximately two-thirds of the reduction in cardiac output.
  7. The reduced leg blood flow in DE was accompanied by an even greater increase in femoral arterial-venous O2 (a-vO2) difference.
  8. It is concluded that blood flow to the exercising muscles declines significantly with dehydration, due to a lowering in perfusion pressure and systemic blood flow rather than increased vasoconstriction.

PRACTICAL TAKEAWAY

This study suggests that dehydration will have an impact on performance and as soon as 2h15' into an event due to reduced blood flow. Therefore, I would suggest that staying hydrated is an important aspect of performing well in endurance sports. Hydration strategies can range from drinking-to-thirst to a structured hydration plan. My recommendation is to test a range of different hydration strategies in training to see what works best for each athlete. A good place to start would be to read this thread of my notes from Allen Lim's presentation at the TrainingPeaks Endurance Coaching Summit. It covers osmolality and gastric emptying which are important for a hydration plan.


EQUIPMENT: Variability in running economy of Kenyan world-class and European amateur male runners with advanced footwear running technology

Recently I've shared multiple studies on supershoes (search for "shoes" on the resources page). A consistent theme has been the variability of performance benefits of different shoes for different runners. This study set out "to measure running economy on a laboratory treadmill in advanced footwear technology compared to a traditional racing flat in world-class Kenyan versus European amateur runners".

STUDY DETAILS

  1. Seven world-class Kenyan and seven amateur European male runners completed a maximal oxygen uptake assessment and submaximal steady-state running economy trials in three different models of advanced footwear technology and a racing flat.
  2. Laboratory results revealed large variability in both world-class Kenyan road runners, which ranged from a 11.3% drawback to a 11.4% benefit, and amateur Europeans, which ranged from a 9.7% benefit to a 1.1% drawback in running economy of advanced footwear technology compared to a flat.
  3. The post-hoc meta-analysis revealed an overall significant medium benefit of advanced footwear technology on running economy compared with traditional flats.
  4. Variability of advanced footwear technology performance appears in both world-class and amateur runners, suggesting further testing should examine such variability to ensure validity of results and explain the cause as a more personalized approach to shoe selection might be necessary for optimal benefit.

PRACTICAL TAKEAWAY

In general, supershoes appear to be beneficial for road running performance. However, there is a broad range of responses to different shoes which means that competitive athletes should perform tests (a field test is probably easiest) to find the best shoe for them. My advice for shoes is to find shoes that feel comfortable which will be a starting point to narrow down the range of shoes to test. From there, it is important to test the shoes to ensure that they are performance enhancing.


RECOVERY: A randomized controlled trial of manual therapy and pneumatic compression for recovery from prolonged running

Recovery after ultramarathons and long training runs is important to ensure that the full benefit of the training stimulus is achieved and to help with continuity of training. To this end, this study "evaluated effectiveness of four daily post-race treatments of a specific manual therapy (MT) protocol and intermittent pneumatic compression (IPC) compared with supine rest on recovery following an ultramarathon among 56 ultramarathoners".

STUDY DETAILS

  1. Groups were comparable across all characteristics examined, including post-race plasma creatine kinase concentration.
  2. Subject completed timed 400m runs before the race and on days three, five, seven and 14 post- race, and also provided muscle pain and soreness ratings and fatigue scores immediately before and after treatments, and during the 14 days post- race.
  3. Daily subjective measures and 400m run times were not improved by either treatment, but both treatments reduced muscular fatigue scores acutely after treatment following the race.

PRACTICAL TAKEAWAY

It appears that manual therapy and intermittent pneumatic compression are not beneficial for recovery purposes despite acutely reducing muscle fatigue after the session. My recommendation is that these modalities of recovery are optional and for athletes who have access to them they can help reduce muscle fatigue, but athletes who don't have access don't need to worry about missing out.

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