Trends and Topics in Exercise Science

Fitspiration/finstagram

Social media fitness content meant motivate exercise and health behavior, especially popularized during and after Covid Lockdowns

Main Benefit of Social Media and Fitness Trends

Fitness media can reach millions of people quickly and may help when the message emphasizes realistc exercise goals rather than appearance

Main problem of Social Media and Fitness Trends

A large share of influencer content is not credible, may lack credentials, and can encourage extreme body ideals, harsh dieting, or unsafe training

Common Harms of Social Media and Fitness Trends

Increased body dissatisfaction, lower mood, reduced self-attractiveness, thinnessfocused ideals, and overemphasis on appearance instead of function.

No one-size-fits-all approach of Social Media and Fitness Trends

Exercise plans should consider gender, body type, starting fitness level, goals, enjoyment, injuries, nutrition, hydration, and overall well-being.

Sex-based physiology example

Women and men may adapt through different hormonal pathways; females rely more on estrogen and growth hormone, while males rely more on testosterone for anabolic support and recovery.

Practical takeaway

Fact-check claims, evaluate source credibility, and individualize recommendations instead of copying generalized online advice.

Reliability

Consistency of repeated measurements under the same conditions.

Validity

Accuracy of the device compared with the true value or a gold standard.

Common measurements in Wearable Devices

Heart rate, HRV, sleep, GPS distance, steps, activity load, SpO2, skin temperature, VO2max estimates, recovery/readiness scores, and calories burned.

Heart rate (HR)

Reflects cardiovascular response to exercise and stress; elevated resting HR may indicate fatigue, stress, or incomplete recovery

Heart rate variability (HRV)

Variation in time between beats; higher HRV usually reflects better autonomic readiness and adaptability, while lower HRV can suggest stress or overreaching.

HR + RPE together

Using heart rate with rating of perceived exertion is stronger than using either alone for monitoring fatigue and possible overtraining.

Sleep metrics

Wearables estimate sleep duration and stages, but they do not directly measure brain activity and are less precise than polysomnography.

Calories burned

Wearables are better at ranking relative energy expenditure than giving accurate absolute calorie totals; errors can be substantial.

Apple Watch

Generally good HR accuracy at rest and steady exercise, but accuracy drops with rapid arm motion; beat-to-beat HRV during intense exercise is less reliable than ECG.

Polar H10

A chest strap ECG system widely treated as a research-grade standard for heart rate and exact R-R interval measurement.

Oura Ring

Strong for nocturnal HR/HRV and sleep metrics; readiness score uses sleep, HR, temperature, and prior activity

WHOOP

Emphasizes strain and recovery scores based on HR, sleep, respiratory rate, temperature, blood oxygen, and movement data

Garmin

Strong for GPS, endurance metrics, and VO2max estimates; useful for running and outdoor training.

Catapult

Team-sport monitoring system that measures GPS/IMU variables such as total distance, speed, accelerations, decelerations, and player load.

Cold water immersion (CWI)

Brief immersion in cold water, typically below 50°F, usually for 1-5 minutes but sometimes longer.

Acute physiological response in CWI

Rapid Skin and superficial muscle cooling causes vasoconstricition, slower nerve conduction, and reduced edema.

DOMS in CWI

CWI may not help soreness immediately after eccentric exercise, but it often reduces delayed soreness at 48-96 hours

Perceived recovery in CWI

Immediate recovery feelings are mixed, but some studies show small favorable effects later in the recovery window

Creatine Kinase (CK) in CWI

CWI does not consistenly reduce CK early after eccentric exercise; benefits depend on exercise type and exposure duration

Performance recovery in CWI

CWI may help short-term recovery of muscular power, but evidence is weak for recovery of strength, endurance, and flexibility

Catecholamine response in CWI

Cold exposure rapidly increases norepinephrine and produces a strong sympathetic stress response with hypeventilation and shivering

Stress and mood in CWI

Cortisol may rise first and then decrease later; some mood benefits may come from later neurotransmitter and autonomic shifts rather than immediate calm

Autonomic balance/ HRV in CWI

Post-exercise CWI can briefly improve parasympathetic reactivation and cardiac autonomic regulation.

Sleep and CWI

Results are mixed; some people fall asleep faster due to cooling, while others struggle because adrenaline and alertness rise after exposure.

Metabolism in CWI

Cold activates brown adipose tissue, non-shivering thermogenesis, and fat mobilization, which can increase short-term energy expenditure

Blunting response in CWI

Using CWI after resistance training can reduce anabolic signaling, protein synthesis, satellite cell activity, and hypertrophy gains

Inflammation tradeoff in CWI

CWI lowers pain, swelling, and stiffness in the short term, but this can slow deeper repair and growth signaling.

Best fit for CWI

Frequent competition, tournaments, or situations where next-session readiness matters more than long-term hypertrophy

Muscle growth and CWI

Avoid routine post-lift use if hypertrophy is the main goal

Heated workouts

Exercise performed in high temperatures, often around 90-105°F, sometimes with elevated humidity.

Acute response

Higher heart rate at the same workload, greater sweat and electrolyte losses, greater perceived exertion, and higher demand on hydration and thermoregulation.

Heat Acclimation

With repeated exposure, people can develop lower heart rate at the same workload, improved sweating efficiency, plasma volume expansion, and better heat tolerance

Flexibility Claim in heated recovery, saunas and heated classes

A single heated class does not clearly improve flexibility more than the same session performed in normal temperatures

Detoxification Claim in heated recovery, saunas and heated classes

Sweat does excrete some substances, including some heavy metals, but detox claims are often oversimplified and overstated in marketing

Heated Recovery/ Sauna acute effects

Heat increases heart rate, cardiac output, peripheral circulation, vasodilation, and sweat loss

Sauna recovery rationale

Better blood flow and relaxation may reduce stiffness and sorenss and support tissue recovery

Performance Effects with heated classes, saunas and heated recovery

Some studies suggest reduced sorenss or better perceived recovery, but timing and sport matter; heavy sauna exposure after a hard session can hurt next-day performance.

Endurance adaptation in heated classes, saunas and heated recovery

Repeated sauna use may improve VO2 max, lactate threshold, heat tolerance, and cardiovascular adaptation in some settings

Potential Mechanisms

Improved blood flow, heat shock proteins, thermoregulatory adaptation, cardiovascular adaptation, and psychological recovery effects

Heated recovery, saunas and classes

Can be a stressor as well as a recovery tool. Dose, timing and hydration matter

Sauna supporting adaptations

May support endurance adaptation, but it is not automatically beneficial after every session

Peptides

Short amino acids chains that act as a signaling molecules, can mimic hormone-like effects, and may target growth, repair, metabolism, or tissue-specific processes.

Peptides vs steroids

Steroids broadly mimic testosterone and can drive rapid anabolic changes;

peptides are presented as more targeted, but many performances-enhancing peptides are still banned and risky

Gorwth Hormone releasing peptides (GHRPs)

Examples include ipamorelin and CJC-1295; they stimulate growth hormone release, increase IGF-1, and are associated with anabolic and lipolytic effects

IGF-1

Important in muscle maintenance and repair; linked with lean mass, bone mineral density, and fitness measures, but also banned and assoicated with safety concerns

EPO and EPO-mimetic peptides

Increased red blood cell production, oxygen delivery, VO2 max, endurance, and time to exhaustion, but carry major cardiovascular risks and banned

BPC-157 and TB-500

Recovery focused peptides promoted for healing; legal and evidence-based for some joint or tendon outcomes, though direct performance benefits are indirect

Collagen peptides

Support tendon and ligament health; legal and evidence-based for some joint or tendon outcomes, though direct performance benefits are indirect.

Beta-alanine

Precursor that raises carnosine, buffers hydrogen ions, and helps delay fatigue in repeated high-intensity work; legal and evidence-based.

GLP-1 receptor agonists

Drugs such as semaglutide and liraglutide reduce appetite, slow gastric emptying, improve glucose control, and cause significant weight loss.

Lean mass concern with peptides

With GLP-1 drugs, roughly 20-40% of weight loss may come from lean mass depending on dose, duration, and population

Sarcopenia risk

– Loss of muscle mass and function is a key concern, especially for already lean athletes or people who under-eat while using appetite-suppressing drugs.

Athletic implications

For people carrying excess mass, weight loss can improve relative VO2max and movement economy; for lean athletes, unintended lean-mass loss may reduce strength, power, recovery, and immune function.

Tirzepatide

A dual GIP + GLP-1 agonist that may improve body composition and nutrient partitioning more than semaglutide, but athlete-specific evidence is limited.

Retatrutide

A triple agonist affecting GIP, GLP-1, and glucagon receptors; appears highly effective for weight loss but still lacks strong sport-performance evidence

Bimagrumab

An experimental antibody that blocks activin signaling, tends to preserve or increase lean mass while reducing fat mass, but strength gains have been inconsistent

Creatine monohydrate

A legal, well-studied supplement that increases intramuscular phosphocreatine (PCr) and supports rapid ATP resynthesis.

Typical loading protocol of Creatine

About 0.3 g/kg/day or roughly 20 g/day for a short loading phase, then about 2-5 g/day for maintenance.

Main performance effects of Creatine

Often improves maximal strength, power, anaerobic capacity, repeated sprint performance, and total training work

Expected magnitude of Creatine

Many studies report about 5-15% improvements in maximal power/strength and about 1-5% improvement in single sprint performance.

Body mass effect with Creatine

A common early change is about 1-2 kg of body mass gain during the first week of loading, often from increased water retention in muscle.

Training interaction with Creatine

Creatine is especially useful when athletes can use the extra ATP support to increase training volume or intensity over time.

Strength and hypertrophy with Creatine

Across resistance training studies, creatine usually produces larger strength and muscular endurance gains than training alone.

Recovery with Creatine

May improve recovery of performance between intense bouts and may attenuate some markers of muscle damage, soreness, and inflammation.

Female athletes and Creatine

Evidence also supports benefits in female athletes for strength and training adaptation.

Endurance Role

Not a classic endurance supplement, but it may reduce post-exercise muscle damage and support repeated high-intensity efforts within endurance-related sports.

Cognition and memory –

Evidence suggests possible benefits for memory, attention, processing speed, and executive function.

Sleep deprivation and Creatine

A high acute dose has shown ability to partly offset fatigue-related cognitive deterioration under sleep loss.

Concussion/ TBI with Creatine

May have neuroprotective potential before or after mild traumatic brain injury, though this is still an emerging area

Mood/depression

Some studies suggest creatine may augment antidepressant treatment and improve depressive symptoms, especially in women

Intermittent fasting (IF)

An eating pattern that alternates fasting and eating windows rather than focusing only on food type.

Common methods

16:8 time-restricted eating, the 5:2 diet, and alternate-day fasting (ADF).

Weight loss mechanism with Intermittent fasting

Most weight loss comes from reduced total daily energy intake, often by about 10-30%.

Weight loss outcomes with Intermittent fasting

ADF and 5:2 often produce about 4-8% body weight loss over 8-12 weeks; time-restricted eating often produces smaller losses around 3-4%.

Maintenance with Intermittent fasting

Intermittent fasting can help prevent weight regain over follow-up periods in some studies

Compared with calorie restriction and intermittent fasting

IF usually produces similar weight loss to standard calorie restriction when the calorie deficit is similar.

Body Composition

Weight loss commonly includes both fat mass and lean mass, often in roughly a 75:25 ratio, similar to other calorie-restricted diets.

Metabolic switching with intermittent fasting

As liver glycogen falls, the body shifts toward lipolysis, beta-oxidation, and ketone production; AMPK rises and mTOR-driven growth signaling falls.

Autophagy and metabolic flexibility with intermittent fasting

Fasting may support cellular cleanup and improve the ability to shift between glucose, fat, and ketone use.

Resistance training + TRE –

– When energy and protein are matched, most studies show similar strength gains and lean mass maintenance compared with normal eating windows.

Fat loss with TRF –

Time-restricted feeding paired with resistance training may help reduce body fat while preserving muscle.

Hormonal note

Some studies in trained men found reductions in anabolic hormones such as testosterone and IGF-1 despite maintained muscle mass.

Aerobic performance

Ramadan-style fasting can reduce VO2max, especially when dehydration is involved; effects of fasted endurance work are mixed.

Fasted endurance exercise

For long-duration aerobic exercise, pre-exercise feeding improves performance in many studies, though not all.

Sprint / high-intensity work

Fasted sprint interval training may reduce session intensity and volume, and Ramadan fasting may increase RPE and reduce peak power or sport-specific running output.

Big practical point

Performance effects depend heavily on hydration, fueling status, sport demands, total calories, and protein intake.