The running science nerd alert.
October 2023
Learn to train smart, run fast, and be strong with Thomas Solomon PhD
Here are this month's latest research studies on running-related exercise and nutrition science.
The studies are divided into sub-topics — training methods, sports nutrition, supplements, recovery, athlete health, injuries, female athletes, and my beer of the month, etc. — so you can skip to what you’re interested in.
I’ve provided a brief statement about the conclusion of each study, but click on the study title to read the full paper.
My favourite.
Systematic review and meta-analysis: Quantifying the Extent to Which Junior Performance Predicts Senior Performance in Olympic Sports: A Systematic Review and Meta-analysis. Barth et al. (2023) Sports Med 
“ Junior performance has very little predictive value for later senior performance. The finding is robust across different populations (e.g., types of sports, sexes, geographical regions). Effects vary across junior age categories: The younger the junior age category, the lower the correlation between junior and senior performance. ”
Training methods.
Systematic review and meta-analysis: The Additional Effect of Training Above the Maximal Metabolic Steady State on VO2peak, Wpeak and Time-Trial Performance in Endurance-Trained Athletes: A Systematic Review, Meta-analysis, and Reality Check. Rosenblat et al. (2023) Sports Med 
“ A single meso-cycle that includes endurance training above the maximal metabolic steady state (MMSS) will improve V̇O2peak in endurance-trained athletes to a greater extent than training only below MMSS. Sources of clinical heterogeneity such as differences in participant characteristics, exercise mode, and training programming variables do not influence the adaptive responses that occur with adding exercise above MMSS to an endurance training program in endurance-trained athletes. All the studies included in the review were underpowered to detect a significant effect across outcomes because of small sample sizes, which remains a common and critical limitation of laboratory-based training intervention studies. ” Systematic review: Immune consequences of exercise in hypoxia: A narrative review. Burtscher et al. (2023) J Sport Health Sci “ Exercise and hypoxia induce distinct and overlapping immune responses. Physiological responses to both exercise and hypoxia regulate metabolism, resilience and effector functions of immune cells. The controlled combination of exercise and hypoxia could be used to harness synergistic/complementary immune effects. Altitude acclimatization, appropriate exercise training and nutritional strategies mitigate increased immune risks of exercising in hypoxia. ” Systematic review and meta-analysis: Optimal type and dose of hypoxic training for improving maximal aerobic capacity in athletes: a systematic review and Bayesian model-based network meta-analysis. Feng et al. (2023) Front Physiol “ The findings of this comprehensive network meta-analysis suggest that “live-high train-low”, “live-high train-high”, and “intermittent hypoxic training” compared with normoxic training are capable of effectively improving the VO2max of athletes. The effect of “live-high train-low” with low altitude training was optimal, and the hypoxic type of residential environments (simulated or natural) did not affect the results. This observation can provide a useful reference for future site selection of an altitude base. ”
Supplements.
Systematic review and meta-analysis: Limited Effects of Inorganic Nitrate Supplementation on Exercise Training Responses: A Systematic Review and Meta-analysis. Hogwood et al. (2023) Sports Med Open “ Despite the increased use and study of nitrate supplementation, most of these data have shown benefits during acute supplementation on exercise rather than a benefit to chronic training outcomes. This systematic review and meta-analysis revealed non-significant improvements in VO2peak or time to exhaustion after exercise training with nitrate supplementation compared to exercise alone. A trend for improvement was found for improvements in healthy participants taking beetroot juice supplementation. These results suggest that nitrate may not have an impact on improving longer-term training outcomes, but studies in this area suffer from low sample sizes and inconsistent study designs. ” Randomised controlled trial: L-menthol administration facilitates breathing comfort during exhaustive endurance running and improves running capacity in well-trained runners: A randomized crossover study. Tsutsumi et al. (2023) Eur J Sport Sci “ L-menthol ingestion facilitated breathing comfort during high-intensity endurance running and improved exhaustive endurance running capacity. Even after exhaustion, L-menthol solution relieved dyspnea sensitivity against external inspiratory resistance. L-menthol ingestion might help athletes improve their endurance running capacity. ”
Recovery (inc. sleep).
Systematic review and meta-analysis: The Impact of Daytime Napping Following Normal Night-Time Sleep on Physical Performance: A Systematic Review, Meta-analysis and Meta-regression. Boukhris et al. (2023) Sports Med “ Daytime napping before afternoon training sessions and/or competition could be recommended as a way to supplement night-time sleep as well as enhance athletic performance. Longer naps might be more beneficial in optimizing physical performance. The impact of a diurnal nap may be affected by (i) nap durations, (ii) time of day of naps, (iii) sleep inertia, and (iv) exercise type. ” Non-randomised controlled trial: Does Cardiorespiratory Fitness Protect Memory from Sleep Deprivation?. Ayotte et al. (2023) Med Sci Sports Exerc “ Sleep deprivation (30 h of uninterrupted wakefulness) caused a significant increase in subjective fatigue and a worse capacity to identify the original 150 images (in a memory test) and discriminate them from distractors. A higher VO2peak (a measure of cardiorespiratory fitness) was significantly associated with better memory scores. The results of this study confirm the importance of sleep before encoding (of images in a memory test) for the effective formation of episodic memory and suggest that maintaining a high cardiorespiratory fitness level could have a protective effect against the effects of sleep deprivation. These results, however, should be interpreted with caution. The fact that VO2peak explained only 41% of the variance in memory performance suggests that the protective effect of cardiorespiratory fitness against sleep deprivation is possibly modest and that other factors may play a mediating role. ” Randomised controlled trial: Sleep restriction between consecutive days of exercise impairs sprint and endurance cycling performance. Dean et al. (2023) J Sleep Res “ Sleep restriction of 3 h/night between consecutive days of exercise, which replicates typical training and competition schedules, negatively affects cycling performance the ensuing day. Sleep restriction has negative implications on sprint and endurance cycling performance and wellness outcomes. It must be a consideration of coaches and support staff that when athletes cannot be blinded to perceived negative situations (i.e., poor sleep, nutrition, travel commitments), these may have implications on performance, independent of physiological changes. Efforts should be made to ensure athletes attain adequate sleep when they are required to exercise on consecutive days. ” Non-randomised controlled trial: Is implementing a post-lunch nap beneficial on evening performance, following two nights partial sleep restriction? Gallagher et al. (2023) Chronobiol Int “ Results obtained from this study indicate that 4 h of partial-sleep-restriction (4 hours of sleep from 02:30 to 06:30) for two consecutive nights, did not have a significant effect on submaximal performance, for measures of bench press and back squat. Despite this, we did report that a post-lunch nap of 30- and 60-minute durations improved mood state, cognitive function, and reduced tiredness. Implementing a nap at 13:00 h did not improve physical performance variables compared to the PSR0 (no sleep restriction) condition; these findings hold important questions regarding the optimal nap duration and timing, when considering prior sleep. As previously discussed, there is a potential dose-response for sleep restriction and performance, therefore having a nap following 4 h of partial-sleep-restriction, may not be beneficial as the individual has had enough sleep to perform submaximal lifts. ”
Athlete health (inc. mental health).
Perspective: Psychological Safety for Mental Health in Elite Sport: A Theoretically Informed Model. Walton et al. (2023) Sports Med “ Psychological safety has increasingly been linked to mental health in elite sports contexts. However, there has been very little discussion or evidence as to how this actually occurs. We propose a theoretically informed model of how psychologically safe environments might lead to increased help-seeking and better mental health outcomes. Specifically, this may occur when individuals feel safe to show their authentic self, perceive their environment to support mental health needs, and psychological harms are minimised throughout the organisation or team. This is the first conceptualisation of how psychological safety in elite sport may contribute to enhanced mental health outcomes. The model is testable, and further studies are now necessary to support or adapt the different processes we outline. ” Systematic review: Mental Health in Ultra-Endurance Runners: A Systematic Review. Thuany et al. (2023) Sports Med “ Eating disorders, exercise addiction/dependence, perceived stress, depressive symptoms, sleep disorder, anxiety, and psychological health are the most studied mental health issues in ultra-endurance runners. The prevalence of mental health issues in this group varied widely, with exercise addiction and eating disorders presenting the highest prevalence. Future comparative studies are needed to better understand sex differences and positive outcomes associated with participation in ultra-endurance running among nonprofessional athletes. It is important to continue investigating mental health issues among ultra-endurance runners to better understand the risk factors and develop interventions to promote the well-being of these athletes. ”
Injury and rehab.
Observational study: "Couch-to-5k or Couch to Ouch to Couch!?" Who Takes Part in Beginner Runner Programmes in the UK and Is Non-Completion Linked to Musculoskeletal Injury? Relphet al. (2023) Int J Environ Res Public Health “ The Couch-to-5k programme (a beginner runner programme aimed at increasing physical activity in the UK) has the potential to attract groups who are more likely to be inactive (women, overweight and middle-aged). However, a key finding of this study was the high level of dropout during this Couch-to-5k programme. This drop out was linked to the programme’s progressive design and suffering potential MSK injury. Therefore, future research should consider how to better support individuals during Couch-to-5k and other beginner physical activity initiatives. MSK injury prevention information should be provided at the start of the programme, including strength and flexibility exercise and injury treatment options. ”
The placebo effect.
Randomised controlled trial: The placebo effect of a pink non-caloric, artificially sweetened solution on strength endurance performance and psychological responses in trained individuals. de Salles Painelli et al. (2023) Nutr Health “ In conclusion, the ingestion of a pink non-caloric, artificially sweetened solution improved strength endurance performance in strength-trained individuals, despite the comparable psychological responses to exercise. Future nutritional supplement studies need to take into account the influence of the drink color when investigating the ergogenic effects of sport-drinks. ”
Female athletes and sex differences.
Observational study: The Influence of Menstrual-Cycle Phase on Measures of Recovery Status in Endurance Athletes: The Female Endurance Athlete Project. De Martin Topraninet al. (2023) Int J Sports Physiol Perform “ This study showed that menstrual cycle phase significantly influenced several commonly used measures of recovery status, although the effects were all small. Since mental readiness to train did not significantly vary between menstrual cycle phases, changes in mental readiness to train throughout the menstrual cycle are most likely influenced by other factors than menstrual cycle phase. The generalizability of these findings is limited to ovulatory menstrual cycles with a duration between 21 and 35 days and a luteal phase longer than 10 days. In summary, although statistically significant, the findings had negligible to small effect sizes, indicating that menstrual cycle phase is likely not the main determinant of changes in measures of recovery status, but rather one of the many possible stressors. ” Randomised controlled trial: A 2-yr Randomized Controlled Trial on Creatine Supplementation during Exercise for Postmenopausal Bone Health. Chilibeck et al. (2023) Med Sci Sports Exerc “ Two years of creatine supplementation and exercise in postmenopausal women had no effect on bone mineral density; yet, it improved some bone geometric properties at the proximal femur. ”
And, to help you wash down the latest evidence, here's a snifter from my recent indulgence...
Beer of the month:
Battenburg from Yonder Brewing (UK).
Pastry stout (ABV = 8.5%).
Rating of Perceived beer Enjoyment = 8½/10
Hazelnut to the eye, syrupy to the nose, a creamy mouth feel, and a taste of sweet almond that lingers in the aftertaste as if to say “you've just eaten a slice of battenburg”.
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Disclaimer: I occasionally mention brands and products but it is important to know that I am not affiliated with, sponsored by, an ambassador for, or receiving advertisement royalties from any brands. I have conducted biomedical research for which I have received research money from publicly-funded national research councils and medical charities, and also from private companies, including Novo Nordisk Foundation, AstraZeneca, Amylin, A.P. Møller Foundation, and Augustinus Foundation. I’ve also consulted for Boost Treadmills and Gu Energy on their research and innovation grant applications and I’ve provided research and science writing services for Examine — some of my articles contain links to information provided by Examine but I do not receive any royalties or bonuses from those links. These companies had no control over the research design, data analysis, or publication outcomes of my work. Any recommendations I make are, and always will be, based on my own views and opinions shaped by the evidence available. My recommendations have never and will never be influenced by affiliations, sponsorships, advertisement royalties, etc. The information I provide is not medical advice. Before making any changes to your habits of daily living based on any information I provide, always ensure it is safe for you to do so and consult your doctor if you are unsure.