Applied Sports Science Newsletter

Welcome to this week’s edition of Applied Sports Science! We've curated six groundbreaking studies that are reshaping how we approach training, nutrition, and health management.

Table of Contents

• Iron Therapy Transforms Performance in Female Athletes

• In Person Exercise Beats Home Workouts

  • Support Us

• Pre-Workout Supplements: Marketing Hype?

• Digital App Tackles Menopause Symptoms

• Beta-Alanine Boosts Endurance in Young Runners

• Blood Test May Predict Muscle Loss in Aging

Study 1

🩸Iron Therapy Transforms Performance in Female Athletes

(Effect of intravenous iron therapy on exercise performance, fatigue scores, and mood states in iron-deficient recreationally active females of reproductive age: a double-blind, randomised control trial (IRONWOMAN Trial) (Dugan et al., 2025))

Researchers investigated whether intravenous iron therapy could help recreationally active women struggling with iron deficiency. Twenty-six iron-deficient but non-anemic females received either 1000mg of iron or a placebo, with performance tracked over four weeks.

What They Found:
The iron group experienced dramatic improvements in fatigue levels (13-22% reduction), and running economy improved by 5%. Surprisingly, their maximum oxygen uptake (VO₂peak) didn't change, but they could run more efficiently at the same speeds. Serum ferritin levels skyrocketed from around 9-12 μg/L to over 500 μg/L within just four days.

Study Strengths:

• Rigorous double-blind design with comprehensive fatigue assessment

• Focused on an understudied population (recreationally active females)

• Used advanced techniques like CO rebreathing for precise measurements

Study Weaknesses:

• Small sample size (only 26 participants) limits confidence in results

• Short follow-up period (4 weeks) - we don't know the long-term effects

• High individual variability in responses

What This Means:

• Clinicians: Consider IV iron for iron-deficient female athletes experiencing fatigue, but expect variable responses requiring personalized approaches

• Coaches: Focus on fatigue reduction as a pathway to better training quality, even when VO₂max doesn't improve

• Sports Scientists: Explore non-blood-related mechanisms like mitochondrial function

Comparison to Previous Research:
This study confirms earlier findings that iron improves fatigue and running economy without boosting VO₂max. However, it's the first to show such high variability in individual responses, emphasizing the need for personalized iron protocols.

Study 2

🏃‍♂️ In-Person Exercise Beats Home Workouts for Heart Patients

Exercise type and settings, quality of life, and mental health in coronary artery disease: a network meta-analysis (Toval et al., 2025)

This massive analysis combined 36 studies involving 3,534 coronary artery disease patients to compare different exercise approaches. Researchers looked at high-intensity interval training (HIIT), moderate-intensity training, and combined programs, delivered either in person or at home.

What They Found:
In-person exercise programs significantly improved quality of life, reduced depression by 55%, and slashed anxiety by 116% compared to usual care. Home-based programs showed virtually no benefits. Interestingly, the type of exercise (HIIT vs moderate intensity) didn't matter - location was everything.

Study Strengths:

• Largest analysis of its kind using advanced statistical methods

• Controlled for factors like program duration and exercise volume

• Robust sensitivity analyses supported the findings

Study Weaknesses:

• Limited data on sleep and cognitive outcomes (only 2 studies each)

• High variability in exercise protocols across studies

• No brain imaging or neurobiological measures

What This Means:

• Clinicians: Prioritize supervised, in-person exercise programs for heart patients to maximize mental health benefits

• Coaches: HIIT and moderate training work equally well - focus on getting patients to in-person sessions

• Sports Scientists: Urgent research needed on optimizing home-based programs with digital monitoring

Comparison to Previous Research:
This study confirms that supervised exercise beats unsupervised training for mental health benefits. However, it's the first to quantify that in-person programs provide 2-3 times larger benefits than home-based alternatives.

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Study 3

💊 Pre-Workout Supplements: Marketing Hype or Real Benefits?

Pre-workout multi-ingredients or carbohydrate alone promote similar resistance training outcomes in middle-aged adults: a double-blind, randomized controlled trial (Puente-Fernández et al., 2025)

Forty-three middle-aged adults (including 26 peri/postmenopausal women) completed six weeks of resistance training while taking either a multi-ingredient pre-workout supplement or simple carbohydrates. The study tested whether fancy supplements outperform basic carbs.

What They Found:
Both groups improved equally in fat loss (1.4 kg vs 1.0 kg), muscle gain (0.9 kg vs 0.8 kg), and strength. The only difference? The supplement group lost slightly more waist circumference (1.8 cm). No differences in strength, power, or endurance between groups.

Study Strengths:

• Double-blind design with proper randomization

• Included understudied middle-aged women

• Comprehensive body composition and performance testing

Study Weaknesses:

• Small sample size and short duration (6 weeks)

• Limited dietary control outside supplementation

• No investigation of underlying mechanisms

What This Means:

• Clinicians: Simple carbohydrates may be sufficient for resistance training adaptations in middle-aged adults

• Coaches: Cost-effective carb sources like maltodextrin can replace expensive commercial pre-workouts

• Sports Scientists: Question the value of complex supplements in non-athletic populations

Comparison to Previous Research:
This aligns with studies showing minimal added benefit of multi-ingredient supplements over basic carbs/protein in trained individuals. However, it's the first to focus on peri/postmenopausal women, suggesting that hormonal status may affect supplement responses.

Study 4

📱 Digital App Tackles Menopause Symptoms Head-On

Evaluating a Mobile Digital Therapeutic for Vasomotor and Behavioral Health Symptoms Among Women in Midlife: Randomized Controlled Trial (Duffecy et al., 2025)

One hundred forty-nine women experiencing problematic hot flashes and behavioral health symptoms used either the Caria mobile app or received standard educational materials for six weeks. The app provided cognitive behavioral therapy, mindfulness exercises, and peer support.

What They Found:
The app group saw a 17.1% reduction in hot flash severity compared to 6.8% in controls. Depression scores dropped by 12.3% with no change in controls. Sleep quality improved significantly in the first three weeks for app users. Interestingly, both groups showed reduced anxiety, suggesting educational materials alone help with anxiety management.

Study Strengths:

• Rigorous double-blind randomized design

• Comprehensive assessment of multiple symptom areas

• High user engagement (average 53.2 logins over 6 weeks)

• Targeted the underserved demographic

Study Weaknesses:

• Sample was predominantly white (79.2%) and highly educated (60% college+)

• Digital recruitment may have selected tech-comfortable participants

• Participants had relatively mild baseline symptoms

• No follow-up beyond 6 weeks

What This Means:

• Clinicians: Digital interventions offer a non-pharmacological option for managing menopausal symptoms

• Sports Scientists: Demonstrates feasibility of digital approaches, but needs more diverse study populations

• Coaches: Accessible self-management tool addressing multiple symptoms without medication side effects

Comparison to Previous Research:
The depression reduction effect size (0.45) matched therapist-delivered interventions and exceeded typical unguided digital interventions (0.27). This extends previous findings by showing digital delivery can achieve similar outcomes to in-person care.

Study 5

⚡ Beta-Alanine Boosts Endurance in Young Runners

Beta-alanine supplementation improves time to exhaustion, but not aerobic capacity, in competitive middle- and long-distance runners (Marko et al., 2025)

Twenty-seven competitive adolescent runners (ages 15-19) took either beta-alanine supplements or placebo for four weeks. Males received 6.4g daily, females 4.8g daily, while maintaining identical training programs.

What They Found:
Beta-alanine improved time to exhaustion by 6.5% compared to just 1.4% in the placebo group. The supplement group also showed a 4.8% increase in oxygen uptake at the second ventilatory threshold, while the placebo group decreased by 6.6%. During submaximal running, heart rate and breathing efficiency improved by 4%.

Study Strengths:

• Double-blind, placebo-controlled design with proper randomization

• Measured multiple physiological parameters including ventilatory thresholds

• Focused on competitive adolescent athletes (understudied population)

• Both groups maintained identical training

Study Weaknesses:

• Small sample size (only 23 completed the full protocol)

• Short 4-week duration represents the minimum threshold for effects

• Didn't directly measure muscle carnosine levels

• Eight of eleven subjects experienced mild tingling side effects

What This Means:

• Coaches: Beta-alanine may benefit adolescent runners in events requiring sustained high-intensity effort

• Sports Scientists: Future studies should examine longer supplementation periods and direct muscle measurements

• Clinicians: While it doesn't increase maximum aerobic capacity, it can enhance endurance performance

Comparison to Previous Research:
The 6.5% improvement aligns with adult studies showing 2.5-13% improvements. This is one of the first studies demonstrating these effects in adolescent athletes, extending evidence to younger populations.

Bonus Study

🔬 Blood Tests May Predict Muscle Loss in Aging

Biomarkers for sarcopenia, muscle mass, muscle strength, and physical performance: an umbrella review (Liu et al., 2025)

This comprehensive review analyzed 22 systematic reviews covering biomarkers for sarcopenia (age-related muscle loss) across multiple categories: inflammatory, metabolic, hormonal, amino acid-related, and genetic markers.

What They Found:
The creatinine to cystatin C ratio emerged as the most frequently used diagnostic biomarker with moderate accuracy (78% correct diagnoses). Inflammatory markers like interleukin-6, C-reactive protein, and tumor necrosis factor-alpha were elevated in sarcopenia patients. Metabolic markers (albumin, triglycerides) and amino acids (leucine, isoleucine) were lower in affected individuals.

Study Strengths:

• Comprehensive scope examining multiple biomarker categories

• Followed rigorous review guidelines with validated quality assessment tools

• Applied evidence grading approach for each biomarker

• Focused on clinically relevant diagnostic markers

Study Weaknesses:

• Significant variability in study populations and diagnostic criteria

• Most biomarkers had very low-quality evidence

• Excluded gray literature potentially missing studies

• Regional differences in diagnostic criteria affect interpretation

What This Means:

• Clinicians: The creatinine/cystatin C ratio shows promise but should be interpreted cautiously given moderate accuracy

• Sports Scientists: Future studies should develop multi-biomarker models accounting for age, sex, and health conditions

• Coaches: Biomarkers may help evaluate intervention effectiveness even when subjective improvements aren't obvious

Comparison to Previous Research:
This review confirms that inflammatory biomarkers are elevated in sarcopenia and decrease following interventions. It extends previous knowledge by comprehensively categorizing biomarkers and identifying those with the strongest evidence, particularly highlighting amino acid biomarkers potential role.