RESEARCH: Studies from 14 to 20 Oct 24
Sharing research and insights from coaches, scientists and athletes to help us improve endurance performance.
This week’s quick summary:
Immune consequences of exercise in hypoxia
Placebo effect of caffeine
Training regimen of an elite ultramarathon runner
The impact of two weeks’ repetitive gut training during exercise
Exercise training increases size of hippocampus and improves memory
ALTITUDE: Immune consequences of exercise in hypoxia
Exercise is an internally-generated stress on the body, while altitude (or hypoxia) is an environmentally-generated stress. Adaptation to these stressors can improve performance; however, they may also impact the immune system. In this review, the authors aim to determine "the impact on immune responses of exercise and of hypoxia, both independently and together, with a focus on specialised cells in the innate and adaptive immune system".
REVIEW DETAILS
The study examined how exercise type, dose, and individual characteristics affect immune outcomes, as well as how hypoxia modulates immune functions based on hypoxic dose and individual response capacity.
The researchers reviewed existing literature on immune system regulation by tissue oxygen levels and the immune responses related to exercise and hypoxia.
They focused on specialised cells in both the innate and adaptive immune systems.
The review explored mitochondrial, antioxidant, and anti-inflammatory mechanisms underlying adaptations that improve cellular metabolism, resilience, and overall immune functions.
Both exercise and hypoxia substantially modulate the immune system. While tissue-specific physiological hypoxia continuously regulates the function of immunological niches, exposure to ambient hypoxia or exercising rapidly induces the activation of immune cells or immunosuppresion.
The overlapping effects of exercise and hypoxia are potentially deterimental to the immune system. Even low exercise intensities may increase oxidative stress and cellular/tissue damage and eventually compromise immune function if performed under hypoxic conditions.
PRACTICAL TAKEAWAY
The authors of this review emphasise the importance of managing the combination of exercise and hypoxia to prevent immunosuppression. For athletes, I recommend the following approach when planning altitude training camps:
Allow sufficient time at altitude for adaptation to the stimulus.
Begin with low-intensity sessions and use markers such as Heart Rate Variability (HRV) to guide the progression to higher-intensity workouts.
Ensure that training load metrics account for the additional demands of altitude, allowing for appropriate management of total load.
RELATED RESEARCH
SUPPLEMENT: Placebo effect of caffeine on physiological parameters and physical performance
Caffeine is one of the most effective supplements for improving endurance performance in athletes. However, placebos can also impact performance. In this study, the authors aimed "to analyse the placebo effect associated with the belief in the intake of a high dose of caffeine (9 mg/kg) on HRV, resting HR and both upper- and lower-body strength tests".
STUDY DETAILS
The study involved 18 strength-trained participants (average age 19.7 years) who completed two trial days: a placebo condition and a control condition.
Participants' heart rate and HRV were measured during 15 minutes of rest, followed by bench press and squat tests at 50%, 75%, and 90% of their one-repetition maximum.
The placebo condition involved participants believing they had consumed a high dose of caffeine (9 mg/kg), when in fact they had ingested a placebo.
Results showed no significant differences in most strength variables between conditions, but resting heart rate decreased and mean RR interval increased in the placebo condition.
Participants reported side effects such as increased activeness and nervousness in the placebo condition, despite not actually consuming caffeine.
PRACTICAL TAKEAWAY
The study's results indicate that while the belief of consuming caffeine may not significantly improve strength performance, it can lead to a reduction in resting heart rate. Importantly, as none of the participants actually consumed caffeine, and performances were similar in both conditions, this suggests that studies demonstrating caffeine's benefits are likely showing the actual effects of caffeine consumption rather than a placebo effect.
Based on these findings, my recommendation for athletes is to continue using caffeine for performance enhancement. The optimal dosage appears to be 3-9 mg/kg of body weight, taken approximately one hour before the event.
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TRAINING: Training regimen of an elite ultramarathon runner: A case study of what led up to the 24-hour World-Record run
Research on elite performers and world record-breaking athletes is fascinating, as it can provide valuable insights despite the difficulty in replicating their exact training regimes. This study aims to "examine the training regimen of an elite ultramarathon runner who broke 8 world records in 2021 and 2022, including the 24-hour run in which he ran 319.6 km in September 2022".
STUDY DETAILS
The study analysed training data from 28 December 2020, to 17 September 2022, collected from the Strava application and recorded on a Coros watch.
The subject completed five training blocks with weekly volume averaging 172.1 to 263km.
Peak running volume occurred approximately 3.2 weeks before races, reaching a maximum of 378km per week.
Recovery weeks following races emphasised less running (19 km/week) and more cross-training.
Interval workouts (1 to 10km repeats) were incorporated throughout training blocks, and the average pace during the 24-hour world-record run (4:30/km) closely matched the overall average training pace.
PRACTICAL TAKEAWAY
A few interesting details from this study were: the large training volume completed, the consistent emphasis on speed (despite preparing for a very long event), and the 3-week taper.
Based on these findings, I recommend the following for athletes:
Incorporate regular speed training into your programme, even when preparing for long-distance events.
Maximise training volume within personal constraints, considering factors such as recovery capacity, lifestyle stress, and other commitments.
Tailor the taper period to your training volume:
For high-volume training, implement a longer taper (e.g., 3 weeks)
For lower-volume training, a shorter taper may be more appropriate
This approach should help optimise performance while respecting individual circumstances and limitations.
RELATED RESEARCH
Elite swimmers’ training patterns in the 25 weeks prior to their season’s best performances
The training intensity distribution among well-trained and elite endurance athletes
PHYSIOLOGY: Gut-training: the impact of two weeks’ repetitive gut-challenge during exercise on gastrointestinal status, glucose availability, fuel kinetics, and running performance
As the trend towards higher carbohydrate intake during endurance exercise continues, athletes should consider incorporating gut training into their programmes. This study aimed "to determine the impact of gut-training protocol over two weeks on gastrointestinal status, blood glucose availability, fuel kinetics, and running performance".
STUDY DETAILS
25 endurance runners participated in an initial gut-challenge trial (GC1), running for 2 hours at 60% VO2 Max while consuming carbohydrate gel-discs every 20 minutes, followed by a 1-hour distance test.
Participants were randomly assigned to three groups for a two-week gut-training intervention: carbohydrate gel-disc (CHO-S), carbohydrate food (CHO-F), or placebo (PLA).
After the intervention, participants repeated the gut-challenge trial (GC2), with measurements including GI symptoms, hydrogen breath test, blood glucose concentration, oxidation rates, plasma I-FABP, and cortisol concentrations.
GI symptoms reduced significantly in GC2 for both CHO-S (60%) and CHO-F (63%) groups compared to PLA, while CHO-S showed lower hydrogen breath test results and higher blood glucose concentrations than CHO-F and PLA.
Distance test performance improved in GC2 for CHO-S (5.2%) and CHO-F (4.3%) groups, but not for PLA (-2.1%).
PRACTICAL TAKEAWAY
The study's results demonstrate that endurance runners can benefit from a two-week gut-training protocol using either carbohydrate gel-discs or food. This approach can effectively reduce gastrointestinal (GI) symptoms and improve running performance.Based on these findings, I recommend that athletes incorporate gut training into their preparation leading up to races. A structured approach, such as the 12-week protocol developed by Aitor Viribay, provides an excellent framework for implementing gut training effectively.
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PHYSIOLOGY: Exercise training increases size of hippocampus and improves memory
While the physiological benefits of training are well-documented, there may also be significant mental and cognitive advantages. This study aimed "to investigate whether aerobic exercise could modify hippocampal volume in late adulthood".
STUDY DETAILS
The study involved 120 older adults in a randomised controlled trial.
Participants underwent aerobic exercise training for an unspecified duration.
Hippocampal volume was measured using neuro-imaging techniques.
The exercise group experienced a 2% increase in hippocampal volume, reversing 1-2 years of age-related loss.
Increased hippocampal volume was associated with higher serum levels of BDNF and improved spatial memory.
PRACTICAL TAKEAWAY
This study showed that for older adults concerned about age-related cognitive decline, engaging in regular aerobic exercise can be an effective strategy to increase hippocampal volume and improve spatial memory. This intervention may help reverse age-related hippocampal shrinkage by 1-2 years, potentially reducing the risk of memory impairment and dementia. My recommendation for everyone is to “train for life”: train for their entire lifespan, and train for the benefits exercise will provide in their lives.
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Quick summary from last week’s paid newsletter
Paid subscribers receive a newsletter every week and have full access to all newsletters listed in the archives (485 studies and practical takeaways). Last week, the newsletter covered studies on the following topics:
Defecation after magnesium supplementation enhances performance in triathletes
How do new runners maintain their running, and what leads to others stopping?
Lower lung-volume level alters swimming kinematics
The effects of exercise-based injury prevention programmes on injury risk
Effects of food bar chewing duration during running
