Chiara Gattoni et al., European Journal of Applied Physiology, 2025

The Effects of One‑Night Sleep Deprivation and One‑Night Recovery Sleep on Endurance Cycling Performance
This randomized controlled trial explored how 25 hrs of total sleep deprivation (SD), followed by a night of recovery sleep, impacted endurance cycling performance in 26 male amateur cyclists and triathletes. The SD group showed elevated perceived effort and more negative affect during a 40-minute moderate-intensity ride, but no significant decline in performance during a subsequent 20-minute all-out time trial. After a single night of recovery sleep, both perceptual and predicted time-to-exhaustion metrics returned to baseline. Vigilance and mood were also restored. The control group (normal sleep) showed no notable changes. HR and lactate were largely unaffected throughout. This is the first controlled study to test how a single recovery night impacts physical performance across three consecutive days of exercise testing, simulating the rhythm of multi-day endurance events.

Practical takeaways:
– Expect your motivation and mood to dip before performance does. Moderate-intensity endurance performance is impaired after a day without sleep, primarily due to higher perceived effort and negative affect.
– Moderate intensity is more vulnerable than high intensity to sleep loss. Long efforts at moderate effort (like a long climb or flat runnable section) are more likely to feel harder than short intense bursts. Plan your pacing and strategy accordingly.
– A single night of good sleep is enough to restore performance metrics, which is encouraging to some degree. Don’t panic if you lose one night of sleep.
– High-intensity performance (20-min TT) remained stable, even after sleep deprivation.
– Sleep deprivation impairs mood, motivation, and vigilance, which could affect safety, pacing, and decision-making (no surprise right).
– Track perceived effort, not just pace or HR, in multi-day races. RPE was a better indicator of performance impact than physiological measures. If your perceived effort is unusually high on a “normally easy” section, it may be a sleep-related red flag.
– Low-stakes entertainment helped maintain wakefulness during SD. Participants stayed up with light activities like games, movies, and conversation, suggesting that maintaining morale through light stimulation can help if you need to stay awake.
– Train how you race… (with care). Occasional training under mild sleep restriction may help prepare for the unique psychological and perceptual demands of overnight races.

This is a well-conducted RCT with a relevant multi-day structure, combining physiological, neurocognitive, and perceptual measures. However, its exclusion of women and small sample (n=13 per group) limit generalizability. The study doesn’t explore chronic partial sleep restriction, which is likely more common in real-life racing than acute total SD. This study reinforces the importance of psychological readiness and perceptual pacing during sleep-deprived efforts. For 200 milers and stage racers, coaches can build in mindset work for managing perceived effort and mood. Pre-race sleep loading and post-leg recovery sleep should be prioritized. Training under mild sleep restriction (infrequently) might also prepare athletes for real-world racing challenges, though that’s a nuanced tool. Emphasize the restorative power of even one night of solid sleep between stages or after travel.

Grégoire P. Millet, Alexa Callovini, Antoine Raberin – Sports Medicine – Open, 2025

Sex-differences in Mountain Ultra-trail Performance: Look at the Scenery
This current opinion piece argues that the sex difference in performance (typically 9–12% on flat terrain) is larger in mountain ultra-trail races, often exceeding 18%, due to three environment-specific factors: uphill–downhill locomotion, high altitude, and extreme ambient temperatures. The authors draw on physiological, anatomical, and environmental research to explain how female athletes may face greater performance limitations in mountainous ultras compared to flatter ones. For example, uphill running magnifies the impact of lower lean mass and type II fiber proportion in females; altitude exacerbates ventilatory and hypoxic challenges; and cold exposure creates thermoregulatory disadvantages, including a greater risk of Raynaud’s phenomenon.

Practical takeaways:
– Uphill sections amplify sex differences: females may be at a disadvantage due to lower lean mass and anaerobic capacity.
– Downhill isn’t a free win either, muscle mass and risk tolerance may affect female pacing and performance when descending.
– Altitude hits women harder: smaller lungs, higher work of breathing, and greater susceptibility to exercise-induced hypoxemia.
– Cold exposure poses unique challenges for female runners: lower muscle mass, higher surface area-to-mass ratio, and more Raynaud’s.
– Females may benefit from more conservative pacing in these events, whether due to physiology or psychology, this could offset some disadvantages.
– Heat may not be quite the disadvantage it’s often assumed to be for women, once body size and heat load are accounted for, differences shrink.

The theoretical grounding of this study strong and it pulls together decades of scattered evidence. The conclusions lean heavily on sex-based physiological averages, but don’t fully address how training status, acclimatization, or gear choices might mitigate those disadvantages. Plus, female participation rates are still low in many races, skewing comparisons. It is still largely speculative, and doesn’t address training load, adaptation, or behavioral strategies enough. It also lacks intersectional depth: not all females have the same responses, and gender identity, hormone therapy, and sociocultural context are absent here.

As coaches, we need to be more precise with how we prepare female athletes for cold, altitude, and steep terrain. That might include: pre-acclimatization protocols for altitude and cold; strength work targeting downhill durability; pacing plans that account for ventilatory and fatigue thresholds; psychological prep for risk, confidence, and perception of danger; gear strategies (e.g., handwarmers, layering) tailored to female-specific physiology, and; encouraging representation and retention of women in mountainous ultras, to eventually close the density-performance gap. This paper meaningfully contributes to the under-researched area of sex differences in mountain ultra performance. It challenges the often-touted idea that women close the gap in longer events by showing how terrain and environment may flip that narrative.

https://ntnuopen.ntnu.no/ntnu-xmlui/handle/11250/3208079

Physiological and Perceptual Responses to a 2-Week Training-Overload Period in Trained Endurance Athletes: The Role of Training Intensity Distribution
This well-structured, impressive master’s thesis explored how two different training overload strategies, one emphasizing increased low-intensity volume (VOL) and the other increased high-intensity training (INT) affect physiological and perceptual recovery in trained male endurance athletes. Over a 4-week period (1-week baseline, 2-week overload, 1-week recovery), both groups increased training load by ~50–70% (matched by TRIMP). Results showed no decrease in performance during overload, but the VOL group improved more in time-to-exhaustion (+9.5%) after recovery compared to INT (+2.0%). Perceptual recovery (readiness, soreness, fatigue) was also better in the VOL group. Interestingly, while INT appeared less perceptually fatigued during overload, they had more lingering physiological fatigue and didn’t fully bounce back after the recovery week.

Practical takeaways:
– LIT-heavy overload blocks may yield better recovery and longer-term performance gains compared to HIT-focused overloads, esp. if you’re already well-trained.
– Perceptual recovery markers (readiness, soreness, motivation) are sensitive indicators during overload, use them!
– HIT increases submaximal cardiovascular strain and may delay full recovery, even if it doesn’t feel worse in the moment. HIT may produce “silent fatigue.,” perceived as easier but recovering slower
– Submaximal HR and HR recovery can detect persistent fatigue, esp. post-HIT blocks—track those metrics.
– Athletes in INT group didn’t fully recover after just one recovery week. A reminder that intensity = debt and recovery might need to be longer than you think.

The study contrasts with earlier studies that favored HIT for rapid gains, but agrees with newer thinking that emphasizes recovery sustainability. It doesn’t dismantle the value of HIT, but it clearly situates it as higher-risk when used in overload. This research encourages coaches to monitor perceptual fatigue with the same rigor as pace or heart rate. It suggests that LIT-driven overload blocks might be safer and more sustainable, esp. mid-season or in athletes already under other life stresses. Use TRIMP or equivalent load metrics to match total stimulus, but pay close attention to recovery signals. It also reinforces the idea that the week after the block is critical, if recovery isn’t full, don’t layer more intensity.

Zhao X, Chen Y, Li X, Wen W, Zhang J, Qiu J. Frontiers in Nutrition, 2025

Gastrointestinal symptoms among recreational long distance runners in China: prevalence, severity, and contributing factors
This one feels personal. The study surveyed 805 Chinese recreational long-distance runners to explore how common GI symptoms are during races, what causes them, and how runners try to manage them. About 26.1% of runners reported GI issues like bloating, urge to defecate, and stomach pain, esp. during the middle of a race. Nutritional strategies, particularly what and when athletes ate before and during races, had a big impact. Foods high in fat, fiber, protein, or fermentable carbs, and eating within 30 min. of starting a race, were key culprits. Interestingly, both very low and very high training volumes were linked to more GI problems.

Practical takeaways:
– Avoid eating in the 30 min. before a race. A longer gap (2–4 hrs) is safer for digestion.
– Foods high in fat, fiber, protein, or FODMAPs (e.g., legumes, dairy) are more likely to cause GI distress during races, practice your fueling in training.
– Bloating was more likely when runners consumed isotonic gels, sports and energy drinks, and bars.
– GI distress peaked mid-race, esp. in runners under 35 or those with a history of GI issues.
– Runners doing very little (20–50 km/month) or a lot (>500 km/month) were more prone to GI issues.
– Female runners reported fewer distress than males, counter to some prior research.
– Only 5.5% made no dietary adjustments pre-race, but even among those who did, awareness and efficacy varied.

This is based on self-reported data, cross-sectional design. Cultural dietary habits may limit generalizability outside China. This is a well-executed study, and reinforces the importance of personalized fueling plans, esp. gut training. Besides that, I encourage athletes to log pre-race meals and symptoms, experiment with lower-FODMAP options, be wary of last-minute snacks, and monitor monthly volume not just for performance, but GI risk too. Also, normalize that GI issues are common, but manageable, with planning, pacing, and practice.

Tímea Téglás & Zsolt Radak, Frontiers in Nutrition, 2025

Probiotic supplementation for optimizing athletic performance: current evidence and future perspectives for microbiome-based strategies
A topic that always interests me, this paper explores the emerging role of probiotic supplementation in enhancing athletic performance, mental health, and recovery through microbiome modulation. The authors summarize evidence from +100 studies spanning endurance, intermittent, and strength sports, suggesting that certain probiotic strains can reduce inflammation, improve lipid metabolism, alleviate GI distress, and even enhance VO₂max and sleep quality. While benefits vary by strain, dosage, and exercise type, the review concludes that probiotics hold potential, but the field remains young and inconsistent. Importantly, the gut-brain axis and microbiota-liver communication are proposed as plausible mechanisms driving observed changes in performance and recovery. This is one of the most complete overviews yet of probiotic use in sports, though gaps in resistance training data and the variability of strains limit direct prescription.

Practical takeaways:
– Some probiotics (e.g., Bacillus subtilis BS50, multi-strain cocktails) reduce bloating, diarrhea, and gut discomfort in endurance athletes. Could be valuable for runners with race-day GI issues.
– Specific strains like Streptococcus salivarius or L. casei have reduced incidence or severity of upper respiratory infections, common during heavy training or travel.
– Studies report VO₂max increases, improved time-to-fatigue, and better lipid metabolism (via short-chain fatty acid and PUFA profiles), but mostly in multi-strain or long-duration protocols.
– Probiotics may reduce anxiety, improve sleep quality, and support mental flexibility and mood.
– Benefits are not universal, L. helveticus helped in one study, but not in another. Strain, dose, and duration matter more than the label “probiotic.”

No magic bullet. Many studies show no significant effects, esp. with short interventions, non-endurance sports, or generalized dosing. Don’t expect miracles yet. The methodology across cited studies is highly variable. Doses ranged from 1 billion to over 400 billion CFUs, durations from 4 to 16 weeks, and populations from marathoners to dancers. This limits generalizability and raises the risk of cherry-picking positive results. The paper does a solid job noting inconsistencies and calling for strain-specific protocols. That said, I would encourage probiotic testing or trials only with clear symptoms (e.g., recurring GI distress, persistent URTIs) and after basic lifestyle tweaks are addressed. Use athlete-reported symptoms and mood tracking to assess possible benefits. Based on this study, I would prioritize multi-strain supplements used in studies with endurance athletes, esp. in race build-up phases. Be wary of overpromising. This also opens space for broader discussions about the interconnectedness of stress, gut health, and recovery.

Gerasimos V. Grivas, Frontiers in Physiology, 2025

The Physiology and Psychology of Negative Splits: Insights into Optimal Marathon Pacing Strategies
This mini-review explores why running the second half of a marathon faster than the first, aka a negative split, might be the smartest pacing strategy. It synthesizes evidence across physiology and psychology, highlighting that negative splits preserve glycogen, reduce thermal and cardiovascular stress, and enhance performance efficiency. The article discusses the mechanisms behind fatigue, cardiovascular drift, thermoregulation, and biomechanics, and offers training and psychological techniques to help runners implement negative splits effectively. However, the strategy isn’t for everyone, esp. if you’re a first-timer riding the adrenaline wave at mile 1. “Negative splitting requires confidence, patience, and a tolerance for initial underperformance.”

Practical takeaways:
– A conservative first half increases fat utilization in early stages and reduces glycogen depletion and minimizes early fatigue, allowing for a stronger finish. Conserving glycogen for later is particularly critical for avoiding “the wall.”
– Visualization, mindfulness, and mental rehearsal help override the “bank time” urge and reinforce controlled pacing. Knowing where elevation changes, aid stations, or psychological barriers (e.g., boring sections or false flats) occur can help plan a sensible progression strategy.
– Slower early pace keeps core temps rise in check, reducing central fatigue and helping you stay efficient in the heat.
– A gradual build-up in pace reduces cardiovascular drift and perceived exertion. This leads to a more linear rise in effort across the race, not a sharp spike, and helps runners psychologically “save” their surge for the right moment.
– Conservative pacing delays neuromuscular fatigue, helping maintain efficient stride mechanics, reduce ground contact time increases, and avoid movement breakdown seen in positive splits.
– Lower early intensity reduces eccentric load and mechanical stress, minimizing muscle fiber damage and creatine kinase elevations that correlate with mid-race pace drop-offs.
– Long runs with a fast finish, controlled progression runs, and negative split intervals train body and brain for the strategy.
– While tech (e.g., GPS, HR monitors, wearable insoles) is more available, actual skill in using them to adjust pacing is what differentiates success.
– Hills, heat, humidity, crowds, etc., all mess with pacing intentions. Runners need adaptable pacing strategies. Negative splits are great if conditions and course profile allow.


Of course, I’d love to see future work expand on how this strategy adapts to hilly courses or long ultras; terrain and time distort pacing feedback significantly. We can teach negative splits not as an outcome but as a skill. The strategy doesn’t need to be dramatic, even splits with a mild pickup in the last 10K may be enough to reap the benefits. As a coach I build pacing awareness through progressive workouts and talk athletes through the psychology of restraint. Use tools like RPE journaling, visualization prompts, and race simulations to shift their mindset to “build mastery.” Reinforce that being strong in the second half is a signature of a well-trained, well-grounded runner. Pacing isn’t just about split times. It’s a philosophy of readiness and restraint.

Gabriele Ferretti, Federico Boem, Silvano Zipoli Caiani, Biology & Philosophy, 2025

Embodied Cognition, Endurance Running and Evolution
This ambitious philosophical paper brings together the Endurance Running Hypothesis, which argues that our species evolved anatomically for long-distance running with the Evolutionary Embodied Cognition Hypothesis, which emphasizes that our cognitive processes are grounded in our bodily morphology and movement. By synthesizing anatomical, neurobiological, biomechanical, and cognitive science evidence, the authors suggest that endurance running may have catalyzed the development of specific cognitive abilities such as inference, prediction, imagination, and causal reasoning, particularly via the act of tracking prey.

Evolutionary adaptations for endurance (e.g., spring-like tendons, efficient thermoregulation, upright posture) correlate with both physical and cognitive advantages. The Runner’s High may have offered an evolutionary reward mechanism to reinforce persistence hunting. Transient hypofrontality (reduced activity in the prefrontal cortex during sustained effort) might explain why running sometimes produces states of calm, clarity, and flow. Running could have been a form of embodied “cognitive training,” allowing early humans to develop inference, spatial reasoning, and hypothesis-testing through dynamic environmental interaction. Running shaped our bodies and our minds.

This is a philosophical synthesis, not an experimental study. While biologically plausible, many causal claims are speculative. Running is not the reason for human cognition, but it likely played a meaningful part. Just as we avoid singular narratives in coaching, this paper embraces complexity and interdependence. This paper doesn’t just say “we are born to run.” It says: we are born into cognition through running. For me it gives us more reason to believe that running is a way of knowing, of shaping the body and the very architecture of the mind.

Dong-Joo Hwang, Kyeong-Ri Kim, Tae-Kyung Kim – Korean Continence Society, 2025

Diminished Motivation for Voluntary Exercise and Metabolic Dysfunction in Psychiatric Disorders: A Behavioral Perspective on Autism Spectrum Disorder and Depression
For someone dealing with mental illness, this study is a valuable piece of research. Authors explored how motivation for exercise and metabolic health are intertwined in models of autism spectrum disorder (ASD) and major depressive disorder (MDD). Using Shank3B-knockout mice and stress-susceptible mice, the researchers observed reduced voluntary exercise and spontaneous movement in both groups, alongside significant metabolic dysregulation. Despite lower activity during the dark (active) phase, the ASD and MDD mice exhibited higher energy expenditure during rest (light phase), suggesting inefficient or maladaptive metabolism. Takeaway: motivation to exercise may not just be a behavioral issue in psychiatric illness, it could reflect deeper metabolic dysfunction.

Practical takeaways:
– If someone with depression or ASD avoids exercise, it might be tied to metabolic imbalance, not just “low motivation.”
– Exercise timing matters. The surprising spikes in energy usage during rest could suggest disrupted circadian metabolism could influence energy levels and mood.
– Low voluntary exercise in these models tracked closely with stress susceptibility and behavioral despair, meaning we might use changes in spontaneous activity as early signals of decline.
– Future strategies could pair exercise with metabolism-targeting therapies to break the cycle.
– Motivation ≠ laziness. Reframing reduced movement as a biological-metabolic outcome may help dismantle stigma and tailor more compassionate interventions.

Findings come from mouse models; while mechanisms are suggestive, translation to human runners with depression or neurodivergence remains speculative. This study deepens our belief in meeting runners where they are. “Lack of motivation” may be a symptom, not the cause. Not all inactivity is a discipline issue. Coaching must support athletes through ebbing energy cycles and offer flexible, low-pressure entry points for movement. A mood log or shift to curiosity-based training might be more helpful than a standard plan. Coaches should be alert to sudden drops in movement, energy, or mood, esp. if the athlete isn’t overtrained. If an athlete with a history of mental health struggles stops running, we might consider stress load, sleep quality, and metabolic health before pushing accountability. Tools like “tiny run” challenges, intrinsic reward systems, or even deliberate rest phases can help support long-term adherence without pressure. When an athlete ghosts the plan, their metabolism might be crashing the party.

Jacobs et al., Scientific Reports, 2025

Maximal strength training improves muscle-tendon properties and increases tendon matrix remodulation in well-trained triathletes
This randomized controlled study examined whether a 12-week max. strength training (ST) program, on top of regular high-volume endurance training, could improve tendon stiffness and muscle strength in well-trained triathletes, and whether this was mirrored in specific blood biomarkers of tendon remodeling. 18 Sthletes were split into an ST+endurance group and a control (endurance-only) group. The ST group showed significant increases in Achilles (+39%) and patellar (+16%) tendon stiffness, maximal strength (squat 1RM +20%), and serum markers of extracellular matrix remodeling (e.g., MMP-I, MMP-III, decorin). No improvement was seen in running or cycling economy.

Practical takeaways:
– Worth repeating: strength training works, even in high-volume endurance athletes. Your tendons can adapt when you’re running 8–10+ hours/week.
– The study showed acute increases in blood markers and decorin, involved in breaking down and rebuilding collagen. Translation: your body knows it’s laying new bricks.
– Tendon stiffness and 1RM strength increased in tandem. That likely means better force transmission, higher power output.
– Neither running nor cycling economy improved. That’s surprising, and humbling. Tendon adaptation ≠ immediate performance gain.

Improvements in stiffness didn’t translate into better endurance efficiency. This suggests the pathway from strength to endurance performance might be indirect, slower, or mediated by other factors like neural drive, technique, or training phase. This dovetails with my focus on sustainability and adaptability: strength training becomes not just a tool for racing faster but running longer, with more control, into later seasons of life. For trail and ultra runners, whose tendons take a pounding on descents and long climbs, this means building a weekly ST routine focused on slow, high-tension loads (e.g. 3×5-8 reps at ~85–90% 1RM) could be a key part of training longevity. Also: play the long game.

Delphine Maurer, WWU Honors College Senior Project, 2025

Running on Empty: A Review of Relative Energy Deficiency in Sport
Here’s a good study worth reading before and in combination with the next one. This undergraduate review explores the causes, effects, and clinical management of Relative Energy Deficiency in Sport (REDs). Drawing from over a decade of research, the paper outlines how low energy availability (LEA), intentional or unintentional, disrupts normal physiological and psychological function across nearly all bodily systems, regardless of sport, age, or gender. It explains REDs’ evolution beyond the Female Athlete Triad to encompass broader symptoms (e.g., impaired bone, immune, hormonal, cardiovascular function). The review highlights how REDs is chronically underdiagnosed, partly due to poor awareness among coaches, athletes, and healthcare providers, and concludes with a strong case for improved educational and screening efforts.

Practical takeaways:
– REDs impairs performance: reduced muscle strength, low endurance, slower recovery, and decreased motivation are direct consequences.
– REDs can affect any runner, not just elite women. If your energy intake doesn’t keep pace with your training load, you’re at risk.
– Fatigue, mood swings, frequent injuries, or irregular menstruation (or loss of libido in men) may be symptoms of LEA. They’re not “just part of training.”
– Carbohydrate availability matters just as much as total calories. Low-carb athletes may show signs of REDs even if total intake is high.
– Hormonal contraceptives can mask REDs in females by inducing withdrawal bleeding. menstrual function should not be used as a sole marker.
– Screening and early intervention tools exist, like the IOC REDs Clinical Assessment Tool, but are still underused in most training environments.
– Coaches and family physicians often lack the knowledge to identify early REDs signs. Interventions should be combined with cultural and structural support to be effective.

While not original research, it thoughtfully curates peer-reviewed findings into a readable and educational resource. The review could go deeper in a few aspects, such as into performance science literature on energy availability in ultra athletes. Still, for a paper rooted in undergraduate scholarship, it goes above and beyond. A strong review with excellent synthesis, useful for anyone supporting athletes in high-load sports like trail and ultrarunning. In the end, we need to normalize fueling as much as we normalize volume. REDs prevention should be built into athlete onboarding, esp. in adolescents, postpartum athletes, and those returning from injury. I intend to make REDs screening part of intakes, and we should train ourselves to spot the signs early.

Darren Delaney, Amy McGuire, Lorna Doyle et al. | International Journal of Sports Science & Coaching, 2025

Do coaches’ and athletes’ perceptions of relative energy deficiency in sport align? A narrative review
This review explores how coaches and athletes perceive relative energy deficiency in sport (REDs), a condition stemming from low energy availability that can seriously impact health and performance. Despite the rising concern around REDs, only ~3% of participants in REDs-related research since 2018 have been coaches. This study critically examines 343 studies, emphasizing the disconnect between how athletes experience REDs firsthand and how coaches perceive or engage with it from a distance. It highlights key challenges: limited coach education, silence around weight and energy intake, and misalignment in perceived roles and responsibilities within the coach-athlete relationship. .

Practical takeaways:
– Coaches are often undereducated about REDs, despite being key influencers of athlete behavior and training loads.
– Athletes frequently hesitate to discuss nutrition, body composition, or menstrual health with coaches, due to fear of judgment or prior negative experiences.
– Trust, closeness, open communication are critical; when present, they can help prevent REDs or support recovery.
– Weight-focused coaching language and reliance on skinfolds can trigger or exacerbate disordered eating behaviors.
– Aligning coaching practices with up-to-date REDs education can reduce risk and foster long-term health.

Interventions often fail when coaches are excluded from REDs education and prevention strategies, or when they don’t see REDs as part of their responsibility. REDs education needs to be part of coach certification, yes, but also embedded into everyday training language, check-ins, and goal-setting. This review suggests that athletes are most at risk when they don’t feel seen as full humans. For coaches, this means shifting from weight-centric feedback to performance and well-being markers, inviting honest conversations, and partnering with RD/MDT professionals when red flags arise. Create psychologically safe environments where a runner can say “I’m not okay” without fear of being benched.

Bratu et al., Sports, 2025

Sports in Natural Forests: A Systematic Review of Environmental Impact and Compatibility for Readability
This review maps the state of global research on sports activities in natural forests, analyzing 148 peer-reviewed papers from 1993–2024. The authors identified six key research areas, including sports tourism, urban forests, and environmental impacts. The most commonly studied activities were hiking, trail running, mountain biking, and orienteering, praised for their mental and physical health benefits but scrutinized for potential ecological harm. The paper calls for integrated governance that balances conservation with recreation and spotlights the growing importance of urban forest access in climate-resilient cities.

Practical takeaways:
– Activities like trail running, hiking, and mountain biking have proven benefits for mood, stress, and physical health, beyond what urban settings offer.
– Hiking and running are generally low-impact, but skiing, motorized sports, and large trail races can cause serious soil erosion, vegetation loss, and wildlife disruption if poorly managed.
– Access to nearby forested green spaces correlates with higher physical activity and well-being. Runners living within 500m of forest or mixed treescapes were more likely to engage in frequent outdoor movement.
– Eco-tourism and trail races bring visitors and revenue, but can clash with conservation unless carefully planned with stakeholder input, trail rerouting, and limited capacity.

The review excels in scope and organization but falls short in empirical depth and stakeholder inclusion. It found a lack of empirical studies measuring long-term environmental impacts, and little inclusion of forest user voices, suggesting an evidence gap in understanding how runners and land interact over time. The authors note the absence of research from many Global South countries, and little attention is given to the politics of access. Trail runners often see themselves as nature lovers, but again research questions whether we are training like guests or invaders?