Topic
Muscle Hypertrophy
What actually grows muscle. We line up the research on volume, frequency, protein and supplements against gym lore.
Research
Related research
- Randomized controlled trialConfidence: Moderate2014
Alcohol Ingestion Impairs Maximal Post-Exercise Rates of Myofibrillar Protein Synthesis following a Single Bout of Concurrent Training
Parr EB, Camera DM, Areta JL, Burke LM, Phillips SM, Hawley JA, Coffey VG / PLOS ONE
Key point: トレーニング後のアルコール摂取（1.5g/kg体重相当）は筋線維タンパク質合成を最大24%抑制した
- Randomized controlled trialConfidence: Moderate2017
Low-load bench press and push-up induce similar muscle hypertrophy and strength gain
Kikuchi N, Nakazato K / Journal of Exercise Science and Fitness
Key point: 負荷量を適切に設定したプッシュアップは低強度ベンチプレスと同等の上腕三頭筋・大胸筋の筋肥大を示した
- Randomized controlled trialConfidence: Moderate2008
Effect of concurrent endurance and circuit resistance training sequence on muscular strength and power development
Chtara M, Chaouachi A, Levin GT, Chaouachi M, Chamari K, Amri M, Laursen PB / Journal of Strength and Conditioning Research
Key point: 有酸素運動→筋力トレーニングの順序では、筋力・パワー発達が逆の順序と比較して有意に低かった
- ReviewConfidence: Moderate2005
Hormonal responses and adaptations to resistance exercise and training
Kraemer WJ, Ratamess NA / Sports Medicine
Key point: コルチゾールは糖新生・タンパク質異化を促進し、慢性的な高値状態は筋タンパク合成を有意に抑制する
- Randomized controlled trialConfidence: Moderate2017
Crescent pyramid and drop-set systems do not promote greater strength gains, muscle hypertrophy, and changes on muscle architecture compared with traditional resistance training in well-trained men
Angleri V, Ugrinowitsch C, Libardi CA / European Journal of Applied Physiology
Key point: ボリューム等量条件下でドロップセットと通常セットの筋肥大に有意差なし
- Meta-analysisConfidence: Moderate2018
Effects of beta-hydroxy-beta-methylbutyrate supplementation on strength and body composition in trained and competitive athletes: A meta-analysis of randomized controlled trials
Sanchez-Martinez J, Santos-Lozano A, Garcia-Hermoso A, Sadarangani KP, Cristi-Montero C / Journal of Science and Medicine in Sport
Key point: HMBのトレーニング経験者・競技者への筋肉量増加効果は統計的に有意でないケースが多かった
- ReviewConfidence: Moderate2015
Effects of intermittent fasting on body composition and clinical health markers in humans
Tinsley GM, La Bounty PM / Nutrition Reviews
Key point: 16〜24時間の断食では、タンパク質摂取量が確保されていれば顕著な筋タンパク質分解は起きにくい
- Meta-analysisConfidence: High2010
Resistance exercise for muscular strength in older adults: A meta-analysis
Peterson MD, Rhea MR, Sen A, Gordon PM / Ageing Research Reviews
Key point: 50歳以上の成人でも抵抗性運動により筋力が平均25%以上向上した
- ReviewConfidence: Moderate2015
A review of resistance training-induced changes in skeletal muscle protein synthesis and their contribution to hypertrophy
Damas F, Phillips SM, Vechin FC, Ugrinowitsch C / Sports Medicine
Key point: トレーニング開始後1〜4週間の筋力向上の多くは神経系の適応（運動単位の動員効率向上）によるもの
- Randomized controlled trialConfidence: Moderate2016
Longer Interset Rest Periods Enhance Muscle Strength and Hypertrophy in Resistance-Trained Men
Schoenfeld BJ, Pope ZK, Benik FM, Hester GM, Sellers J, Nooner JL, Schnak JA, Bond KF, Carter JM, Aragon AA / Journal of Strength and Conditioning Research
Key point: 3分休憩グループは1分休憩グループと比較して筋肉量の増加が有意に大きかった（上腕二頭筋・大腿四頭筋）
- ReviewConfidence: Moderate2011
Sleep and muscle recovery: endocrinological and molecular basis for a new and promising hypothesis
Dattilo M, Antunes HK, Medeiros A, Monico-Neto M, Souza HS, Lee KS, Tufik S, de Mello MT / Medical Hypotheses
Key point: 睡眠中（特に深睡眠）は成長ホルモン分泌のピークであり、睡眠不足はGH分泌を顕著に抑制する
- Randomized controlled trialConfidence: Moderate2010
Effect of agonist-antagonist complex resistance training on upper body strength and power development
Robbins DW, Young WB, Behm DG, Payne WR / Journal of Sports Sciences
Key point: 拮抗筋スーパーセットは通常のストレートセットと比較して筋力・パワー向上に有意差なし
- ReviewConfidence: Moderate2020
Physiological differences between females and males in resistance training outcomes: a systematic review
Roberts BM, Nuckols G, Krieger JW / Journal of Strength and Conditioning Research
Key point: 女性のテストステロン濃度は男性の約5〜10%であり、同強度のトレーニングでの筋肉量増加の絶対量は男性より少ない
- Randomized controlled trialConfidence: Moderate2015
Effects of Low- vs. High-Load Resistance Training on Muscle Strength and Hypertrophy in Well-Trained Men
Schoenfeld BJ, Peterson MD, Ogborn D, Contreras B, Sonmez GT / Journal of Strength and Conditioning Research
Key point: No significant difference in muscle thickness or lean mass between high-load (3–5RM) and low-load (25–35RM) at 8 weeks
- Meta-analysisConfidence: Moderate2017
Strength and Hypertrophy Adaptations Between Low- vs. High-Load Resistance Training: A Systematic Review and Meta-Analysis
Schoenfeld BJ, Grgic J, Ogborn D, Krieger JW / Journal of Strength and Conditioning Research
Key point: No significant difference in hypertrophy between low-load (≤60% 1RM) and high-load (≥65% 1RM) when volume and effort are equated
- Meta-analysisConfidence: High2017
Creatine supplementation augments gains in strength and lean mass from resistance training (meta-analysis)
Chilibeck PD, et al. / Open Access Journal of Sports Medicine
Key point: Significantly greater lean-mass gains with creatine
- Meta-analysisConfidence: High2018
Protein supplementation augments resistance-training-induced gains in muscle mass and strength (meta-analysis)
Morton RW, et al. / British Journal of Sports Medicine
Key point: Protein adds to lean-mass and strength gains
- Meta-analysisConfidence: Moderate2017
Dose-response relationship between weekly sets (training volume) and hypertrophy (systematic review)
Schoenfeld BJ, et al. / Journal of Sports Sciences
Key point: Dose-response between weekly sets and hypertrophy
Supplements
Related supplements
BCAA (Branched-Chain Amino Acids)
Confidence: ModerateLeucine, Isoleucine, Valine (typically in a 2:1:1 or 4:1:1 ratio)
A supplement consisting of three essential amino acids — leucine, isoleucine, and valine. Multiple meta-analyses report a moderate reduction in delayed onset muscle soreness (DOMS), supporting post-exercise recovery. However, when total protein intake is already adequate, the incremental benefit of additional BCAA supplementation on muscle protein synthesis appears to be limited.
Betaine (Trimethylglycine)
Confidence: ModerateBetaine (Trimethylglycine, TMG)
Betaine is an amino acid derivative that acts as a methyl donor involved in creatine synthesis. Multiple RCTs have reported improvements in upper-body strength and muscle power, though results for lower-body outcomes are mixed. Cardiovascular benefits via homocysteine reduction are also under investigation.
Casein Protein
Confidence: HighCasein (Micellar Casein / Calcium Caseinate)
Casein protein is a milk-derived protein characterized by slow digestion and absorption over 6 to 8 hours. Research suggests that pre-sleep casein intake may enhance muscle protein synthesis overnight. Combining casein with whey protein is thought to optimize both immediate and prolonged amino acid delivery.
EAA (Essential Amino Acids)
Confidence: ModerateNine essential amino acids: leucine, isoleucine, valine, lysine, methionine, phenylalanine, threonine, tryptophan, and histidine
A product containing all nine essential amino acids that the body cannot synthesize on its own. Research suggests that having the full complement of essential amino acids available is advantageous for muscle protein synthesis. BCAAs alone may leave other essential amino acids in short supply, and EAA is thought to provide a more complete substrate.
HMB (Beta-Hydroxy Beta-Methylbutyrate)
Confidence: ModerateBeta-Hydroxy Beta-Methylbutyrate (HMB-Ca or HMB-FA)
HMB is a metabolite of leucine that research suggests may act on both the inhibition of muscle protein breakdown and the promotion of muscle protein synthesis. Evidence supporting its role in preserving lean mass is comparatively stronger in beginners, older adults, and those in a caloric deficit, while results in trained individuals seeking hypertrophy remain mixed across meta-analyses.
Soy Protein
Confidence: ModerateSoy protein (isolate / concentrate)
A plant-based complete protein containing all nine essential amino acids, studied as a practical option for those with dairy allergies or following a vegan diet. Leucine content is somewhat lower than whey, which may result in a slightly smaller muscle protein synthesis response, but research suggests it is a useful tool for meeting total daily protein targets.
Creatine
Confidence: HighCreatine monohydrate
One of the most studied supplements, with strong evidence for efficacy and safety. Supports high-intensity performance and gains in lean mass and strength during resistance training.
Whey Protein
Confidence: HighWhey protein
A convenient way to top up protein that's hard to hit through meals alone. Rich in leucine, which helps trigger muscle protein synthesis. A supplement to total intake — not a magic powder.
Articles
Related reads
- Research vs Bro-science
"Can't Build Muscle After 40" — Myth or Reality? Aging vs. the Research
"I'm too old to build muscle" — a common refrain from trainees in their 40s and 50s. Testosterone and growth hormone do decline with age. But is the muscle-building window actually closed? The research says otherwise.
Shingo Yoshizaki
- Research vs Bro-science
Does Drinking Alcohol Really Not Affect Muscle Growth or Fat Loss? The Casual Drinking Myth vs. Research
"A few drinks on the weekend won't hurt my gains" — convenient thinking about alcohol and training is common. What does the research actually show about alcohol's impact on muscle protein synthesis and fat loss?
Shingo Yoshizaki
- Research vs Bro-science
Can You Actually Build Muscle with Bodyweight Training Alone? The No-Weights Myth vs. Research
"You can't build real muscle without weights" — this belief keeps many people gym-dependent. But when you look at what actually drives hypertrophy, the type of resistance matters less than you might think.
Shingo Yoshizaki
- Research vs Bro-science
Does Cardio After Lifting Really Burn More Fat? The Exercise Order Myth vs. Research
"Do cardio after weights to burn fat once glycogen is depleted" — it's one of the most popular pieces of gym advice. But another camp insists cardio first protects your muscles. We dig into the research on concurrent training order to find out what actually changes.
Shingo Yoshizaki
- Research vs Bro-science
Does Stress Really Melt Your Muscles? The Cortisol Myth vs. Research
"Cortisol breaks down muscle" — widely known, but does that mean training-induced cortisol is harmful? Does work stress dissolve your gains? The impact of acute vs. chronic cortisol elevation on hypertrophy is very different.
Shingo Yoshizaki
- Research vs Bro-science
Do Drop Sets Really Accelerate Muscle Growth Beyond Normal Sets? The Hype vs. Research
Go to failure, then drop the weight and squeeze out more reps — drop sets are popular for supposedly pushing past your limits. But when you match training volume, do drop sets actually outperform straight sets?
Shingo Yoshizaki
- Research vs Bro-science
Is HMB Really a Superior Muscle-Building Supplement to Creatine? The HMB Hype vs. Research
HMB (beta-hydroxy-beta-methylbutyrate), a leucine metabolite, is marketed for stimulating muscle protein synthesis and preventing catabolism. But how well does the "guaranteed gains" claim hold up in research, especially for trained individuals?
Shingo Yoshizaki
- Research vs Bro-science
"I Got Stronger in 2 Weeks" — Is That Muscle or Something Else? Training Timeline vs. Research
Many new lifters feel noticeably stronger after 2–3 weeks. But what's actually changing? How long until real muscle hypertrophy — an increase in muscle cross-sectional area — actually occurs? The research timeline differs from gut feeling.
Shingo Yoshizaki
- Research vs Bro-science
Does Shorter Rest Between Sets Really Build More Muscle? The Interval Myth vs. Research
"Keep rest short to spike growth hormone and stay metabolically stressed" — this gym doctrine has long pushed trainees toward rushed sessions. But what does the research actually say about optimal rest intervals for hypertrophy?
Shingo Yoshizaki
- Research vs Bro-science
Can Supplements Offset Sleep Deprivation's Impact on Muscle? Sleep vs. Supplements
Busy week, only 5–6 hours of sleep — "I'll compensate with extra protein" is a common reassurance. But the research on sleep deprivation and muscle growth suggests the hit is harder than most lifters realize.
Shingo Yoshizaki
- Research vs Bro-science
Are Supersets Really More Efficient Than Straight Sets? The Truth Depends on How You Pair Them
Antagonist supersets on busy days, double the work in half the time — supersets are a gym staple. But does the "supersets are always better" assumption hold up? The answer depends critically on which muscles you're pairing.
Shingo Yoshizaki
- Research vs Bro-science
Will Women Get "Bulky" from Weight Training? The Masculinization Myth vs. Research
"Heavy lifting will make me look manly" — this fear still keeps many women out of the weight room. But the physiology of female muscle development tells a very different story.
Shingo Yoshizaki
- Research vs Bro-science
Is Training Each Muscle Once a Week Really Optimal? Bro Split vs. the Research
"Chest on Monday, back on Tuesday — hit each muscle once a week with maximum volume." The classic bro split is a staple of gym culture. But as research on training frequency and hypertrophy has accumulated, a growing body of evidence suggests that training a muscle only once per week may leave muscle protein synthesis windows on the table. We examine what the research says about frequency when weekly volume is kept constant.
Shingo Yoshizaki
- Research vs Bro-science
Is Eating as Much as Possible Really the Best Way to Bulk?
The idea that eating as much as possible during a bulk leads to maximum muscle growth is a long-standing gym belief. Yet research suggests that excessive calorie surpluses tend to add fat more than muscle. This article examines three key claims behind dirty bulking through the lens of current evidence.
Shingo Yoshizaki
- Research vs Bro-science
Is EAA Really Better Than BCAA? Gym Popularity vs. the Research
EAA (essential amino acid) supplements have surged in popularity over the past few years, with claims that 'BCAAs are outdated and EAAs are simply better' becoming common in gyms and on social media. The argument sounds theoretically sound — but how well does the research actually back it up?
Shingo Yoshizaki
- Research vs Bro-science
Does Cheating Reps with Heavier Weight Build More Muscle? Bro Wisdom vs. Research
Using momentum to handle heavier loads — commonly called 'cheating' — is often promoted as a shortcut to faster muscle growth. But does sacrificing range of motion for heavier weight actually improve hypertrophy? This article examines the claims against research on range of motion, partial vs. full ROM, and injury risk.
Shingo Yoshizaki
- Research vs Bro-science
Do You Really Need 2g of Protein per kg of Bodyweight? Common Wisdom vs. the Research
"Eat 2g of protein per kg of bodyweight" is one of the most repeated nutrition rules in any gym. But does the science actually back that number, or is it overcautious bro-math? We put the claim through three rounds against the meta-analytic evidence.
Shingo Yoshizaki
- Research vs Bro-science
Is the Pump a Signal of Muscle Growth? Common Belief vs. Research
The feeling that 'a great pump means a great workout' is widely shared among lifters. Ever since Arnold Schwarzenegger famously compared the pump to an orgasm, it has been treated as a symbol of hypertrophy. But what does the research actually say about the relationship between the pump and muscle growth?
Shingo Yoshizaki
- Research vs Bro-science
Does Training More Often Mean More Gains? High Frequency vs. What the Research Shows
"Hit the same muscle group three or more times a week and your gains will accelerate" — it's advice repeated across social media and YouTube channels. The logic sounds intuitive, but does simply training more often actually produce more results? When you factor in total volume and recovery, the picture turns out to be more nuanced.
Shingo Yoshizaki
- Research vs Bro-science
Do You Really Need to Train to Failure to Build Muscle? Common Belief vs. Research
"The last rep that breaks your limits is when muscles grow" — this mantra drives many gym-goers to push to failure every single set. Yet a growing body of research suggests that leaving one to three reps in reserve (RIR) produces comparable hypertrophy. Is training to failure a prerequisite for muscle growth, or does it simply raise injury and overtraining risk without meaningful added benefit?
Shingo Yoshizaki
- Research vs Bro-science
Does more protein always mean more muscle? Lore vs research
'In a bulk, just eat tons of protein — the more you take, the more muscle you build.' We test this gym staple against the research on dose–response, the role of training, and age.
Hirotsugu Yoshimura
- Explainer
How to start creatine: do you need to load?
Just take 3–5 g every day. If you want faster saturation, you can load for the first 5–7 days, but it's optional.
Hirotsugu Yoshimura