The running science nerd alert.
November 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, recovery, athlete health, 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.
Narrative review: Considerations of Low Carbohydrate Availability (LCA) to Relative Energy Deficiency in Sport (RED-S) in Female Endurance Athletes: A Narrative Review. Lodge et al. (2023) Nutrients 
“ Women and girls in sports are currently underrepresented in research that has been utilized to develop carbohydrate intake recommendations. Current carbohydrate recommendations and fueling strategies fail to consider female-specific research, adaptations, and fluctuating hormones due to the menstrual cycle or hormonal birth control. Implications of research on low carbohydrate availability will provide more sex-specific guidelines and carbohydrate recommendations that prioritize a proper ratio of macronutrients for optimal functioning. Coaches, athletes, sports dietitians, and other members of the athlete’s care team would be able to use these recommendations and strategies to help support the health and performance of the female athlete. In conclusion, diets with adequate energy and carbohydrate availability support the physiological demands of elite athletes while minimizing unfavorable health and performance consequences. ”
Training methods.
Randomised controlled trial: Running with whole-body electromyostimulation improves physiological determinants of endurance performance - a randomized control trial. Krause et al. (2023) BMC Sports Sci Med Rehabil “ We demonstrated that whole-body electromyostimulation can be safely applied during running; however, no additional effects on physiological determinants of endurance performance were observed when adding whole-body electromyostimulation to high-intensity running. ” Narrative review: A Review of the Potential Effects of the World Athletics Stack Height Regulation on the Footwear Function and Running Performance. Ruiz-Alias et al. (2023) Appl Sci “ With regard to the shoe mass, it is suggested that a stack height difference of 20 mm could induce a meaningful effect on performance. With respect to the midsole properties, it seems that reducing the stack height does not alter the energy returned, given that the lower midsole deformation is counteracted with an increased stiffness. However, it should be noted that this might affect the timing of the midsole deformation and restitution, which should be matched with the mid and propulsive stance phases. Lastly, the curved geometry of the forefoot sole needed to create the teeter-totter effect could be affected by the stack height reduction. However, current racing footwear designs have counteracted this modification by proximately placing the rocker axis and increasing the toe spring. ” Randomised controlled trial: A Influence of the World Athletics Stack Height Regulation on Track Running Performance. Ruiz-Alias et al. (2023) J Strength Cond Res “ In conclusion, the use of the illegal marathon shoe model resulted in a worthwhile improvement of 0.97% (20.04 to 1.98%) in the 3-minute time trial that was mainly explained by a reduced ground contact time. ” Randomised controlled trial: Training Specificity in Trail Running: A Single-Arm Trial on the Influence of Weighted Vest on Power and Kinematics in Trained Trail Runners. Cartón-Llorente et al. (2023) Sensors “ The main findings of this work were that running with an additional load of +10% body mass reduced flight time (effect size: 0.5 to 0.9) and increased DF (effect size: 0.7 to 1.1) and GCT (effect size: 0.4 to 0.9) in level running at 8, 10, 12, and 14 km·h−1, while running with an additional load of 5% body mass did not produce substantial alterations in running kinematics. Although MPO increased linearly with additional loading (effect size: 2.7 to 7.0) at all velocities analyzed, running LSS remained unchanged in the +10% body mass condition and subtly increased in the +5% body mass condition (effect size: 0.2 to 0.3). Therefore, running with lighter loads (i.e., 5% body mass) seems a more appropriate strategy to increase power generation and stimulate lower extremity elastic energy reuse. ” NOTE: this study uses a Stryde device to estimate power and kinematics; consequently, the authors make a large assumption that this device can measure such variables accurately and precisely under different load conditions. Furthermore, their conclusion that “lighter loads (i.e., 5% body mass) seem a more appropriate strategy to increase power generation” is misleading because this is not a training intervention and the study design does not allow us to know whether training with a vest can improve running performance nor does it reveal info about which weight of a vest is most appropriate to achieve such an outcome.
Sports nutrition.
Systematic review: Exploring the Nutrition Strategies Employed by Ultra-Endurance Athletes to Alleviate Exercise-Induced Gastrointestinal Symptoms-A Systematic Review. Ryan et al. (2023) Nutrients “ The findings of this systematic literature review suggest that following a diet low in FODMAPs (fermentable oligosaccharides, disaccharides, monosaccharides, and polyols) has the potential to support ultra-endurance athletes in the management of their exercise-induced gastrointestinal symptoms leading up to and during exercise, as well as throughout the recovery period. Carbohydrates may be more favorable as an energy source during ultra-endurance exercise training and racing, with their adaptation through gut training also existing as a promising strategy to further improve their tolerability. However, research findings regarding the precise carbohydrate blend for optimum performance effects with minimum gastrointestinal symptoms incidence remain trivial and inconclusive. The amount of lactose present in pre-exercise meals and those during the recovery period, similar to the findings for that of medium-chain triacylglycerols supplementation, does not appear to be beneficial for exercise-associated gastrointestinal symptoms attenuation. The findings of this review may be used to guide future research and support sports professionals in their recommendations of practices that improve athletic performance by attenuating such gastrointestinal symptoms. Further research should recruit larger sample sizes, supported by a power calculation, and focus on investigating the impact of specific foods and nutrients on exercise-induced gastrointestinal symptoms complaints and their associated mechanisms. ” Systematic review and meta-analysis: The Effect of Pre-Exercise Hyperhydration on Exercise Performance, Physiological Outcomes and Gastrointestinal Symptoms: A Systematic Review. Jardine et al. (2023) Sports Med “ Pre-exercise hyperhydration appears to acutely increase plasma volume which may reduce heart rate and core temperature during constant work rate exercise to exhaustion compared with control. Implementing pre-exercise hyperhydration may induce gastrointestinal symptoms during exercise in some individuals, with the severity of symptoms potentially associated with the dose, timing and ingestion rate of the hyperhydration strategy. The effect of hyperhydration on time-trial performance is equivocal and provides an area for future research. ”
Recovery (inc. sleep).
Systematic review and meta-analysis: Hydration, Hyperthermia, Glycogen, and Recovery: Crucial Factors in Exercise Performance-A Systematic Review and Meta-Analysis. López-Torres et al. (2023) Nutrients “ Both hyperthermia and dehydration may contribute to elevated glycogenolysis during exercise and poorer glycogen resynthesis during recovery. While core and muscle hyperthermia, resulting from high-intensity or prolonged exercise (internal hyperthermia) or exercising in hot environments (external hyperthermia), appears to be a significant factor contributing to glycogen impairments, it is closely linked to dehydration. Maintaining an appropriate body temperature and ensuring proper fluid intake during and after exercise are essential for optimizing long-term performance. ” Randomised controlled trial: Exogenous Ketosis Improves Sleep Efficiency and Counteracts the Decline in REM Sleep after Strenuous Exercise. Robberechts et al. (2023) Med Sci Sports Exerc “ Strenuous morning and late-evening exercise disturbed sleep architecture as evidenced by reduced REM (rapid eye movement) sleep, increased non-REM sleep, and increased wakefulness after sleep onset. Interestingly, postexercise and presleep intake of ketone ester counteracted the exercise-induced decrease in REM sleep and wakefulness after sleep onset, as well as increased total sleep time and sleep efficiency, but did not impact subjective sleep quality. ”
Athlete health (inc. mental health).
Consensus statement: Surveillance of athlete mental health symptoms and disorders: a supplement to the International Olympic Committee's consensus statement on injury and illness surveillance. Mountjoy et al. (2023) Br J Sports Med “ Sport has the duty of care to protect the health of athletes. We encourage the implementation of the surveillance principles outlined in this paper, and the adaptation of them to a variety of sporting contexts, including the Olympic Games. Adoption of the recommendations outlined above should not only stimulate mental health surveillance and promote mental health literacy, but also may decrease stigma, and improve the quality of mental health surveillance outcomes. The goal of mental health surveillance is to improve athlete health and well-being. ” Randomised controlled trial: Effect of sportswear on performance and physiological heat strain during prolonged running in moderately hot conditions. Ioannou et al. (2023) Scand J Med Sci Sports “ Our results demonstrated that the tested upper body sportswear technologies had similar impacts on running speed at 70% V̇O2peak, physiological heat strain, and perceptual responses without offering any physiological and performance advantage. These findings cannot be attributed to a small study sample size and are in line with previous studies conducted in less thermally stressful conditions and/or at lower exercise intensities, which showed no significant impact of sportswear technologies on well-trained individuals.19, 20, 27 In addition to confirming previous findings on physiological heat strain, the present study tested new sportswear technologies such as compression t-shirts and t-shirts with aluminium dots lining the inside of the garment. We found no significant impact on physiological heat strain and running speed at 70% V̇O2peak in well-trained and national-level athletes. Interestingly, although the present study revealed no significant differences among the tested sportswear, athletes in the study reported experiencing larger areas of suboptimal cooling functionality in some of the tested sportswear technologies. ”
Female athletes and sex differences.
Randomised controlled trial: Psychophysiological Responses to Self-Selected Exercise Intensity Over the Menstrual Cycle: A Randomized Crossover Phase Trial. Garcia et al. (2023) Res Q Exerc Sport “ Some resting psychological responses (i.e., anger, anxiety, behaviour change, pain, and negative affect) were greater during the menstruation phase compared to the mid-follicular phase, whereas other parameters (i.e., fluid retention, anger, behaviour change, and autonomic reactions) were greater during late luteal phase compared to the mid-follicular phase. In the menstruation phase, women reported more negative affective valence (more feelings of it being bad than good) and less motivation to start exercise compared to the other phases. ” Narrative review: Women at Altitude: Sex-Related Physiological Responses to Exercise in Hypoxia. Raberin et al. (2023) Sports Med “ The pulmonary system seems to be one of the functions most impacted by sex differences and exposure in hypoxia, with women becoming more hypoxemic and having a greater work of breathing than men. Cardiac hemodynamics are not impacted by sex in hypoxia, but vascular reactivity is greater in women at rest or combined with exercise; hence, women seem less peripherally limited than men in hypoxia. While sex differences in hematological parameters are well known, they do not impact acute hematological responses to hypoxia (i.e., plasma contraction). Regarding increases in hemoglobin mass, no clear consensus is apparent and the putative sex differences seem due to low iron stores (more common in women). Although these responses are known to be sensitive to sex hormone fluctuations, the effect of menstrual cycle and the influence of menopause on physiological responses to hypoxia remain poorly investigated. All these responses demand further investigation, with appropriate designs to characterize sex-specific differences. While a growing body of evidence has demonstrated the mechanisms that could impact sex-dependent responses to hypoxia, the impact on performance in hypoxia, mountaineering, and susceptibility to severe altitude illness is not yet fully understood. Further work is required to translate these sex differences in responses to hypoxia into practical recommendations, either for reducing the risks at high altitude or for improving performance or health benefits associated with altitude training or hypoxic conditioning. ” Narrative review: Considerations of Low Carbohydrate Availability (LCA) to Relative Energy Deficiency in Sport (RED-S) in Female Endurance Athletes: A Narrative Review. Lodge et al. (2023) Nutrients “ Women and girls in sports are currently underrepresented in research that has been utilized to develop carbohydrate intake recommendations. Current carbohydrate recommendations and fueling strategies fail to consider female-specific research, adaptations, and fluctuating hormones due to the menstrual cycle or hormonal birth control. Implications of research on low carbohydrate availability will provide more sex-specific guidelines and carbohydrate recommendations that prioritize a proper ratio of macronutrients for optimal functioning. Coaches, athletes, sports dietitians, and other members of the athlete’s care team would be able to use these recommendations and strategies to help support the health and performance of the female athlete. In conclusion, diets with adequate energy and carbohydrate availability support the physiological demands of elite athletes while minimizing unfavorable health and performance consequences. ” Scoping review: Barriers and enablers influencing female athlete return-to-sport postpartum: a scoping review. Tighe et al. (2023) Br J Sports Med “ A total of 22 studies exploring the barriers and/or enablers that influence the successful return-to-sport among female athletes postpartum were identified and synthesised in this scoping review. Factors found to significantly influence female athletes successful return-to-sport postpartum include: (1) postpartum recovery time; (2) time to manage motherhood and sport demands; (3) sport organisation policies; (4) stereotypes; and (5) social support. Paid maternity leave that offers job security, travel support for carer and child and affordable and accessible childcare are critical policy inclusions to support female athletes in their return-to-sport postpartum. To advance the current body of evidence, future research should adopt standardised definitions of the ‘postpartum period’ and the ‘athlete’, as well as report when (weeks post birth) athletes returned to sport and what level of sport athletes returned to postpartum. ”
And, to help you wash down the latest evidence, here's a snifter from my recent indulgence...
Beer of the month:
Rapt-Os from Neon Raptor Brewing Co. (UK).
Imperial double stout (ABV = 8%).
Rating of Perceived beer Enjoyment = 5/10
Dark brown to the eye, burnt and almost smokey marshmallow to the nose, sharp, smokey, and chemically on the tongue, and a lingering symphony of artificial breakfast cereal chemicals down the hatch. With a jazzy-looking can and a fun name, I hoped for so much more.
Access to education is a right, not a privilege:
Equality in education, health, and sustainability is important to me. I was lucky to be born into a social welfare system where higher education was free. Sadly, that is no longer true, so I want to provide access to running performance and sports nutrition education to folks from all walks of life. This nerd alert newsletter is just part of that offering. You can find more free educational resources from me, Thomas Solomon PhD, at veohtu.com.
Every day is a school day.
Empower yourself to train smart.
Think critically. Be informed. Stay educated.
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.