Evidence Assessment of Sports Supplements: A Scientific Review of Creatine, Beta-Alanine, and HMB

The Supplement Landscape: Where Science Meets Marketing

The market is flooded with supplements claiming to enhance performance. This article examines the three supplements with the strongest scientific evidence: creatine, beta-alanine, and HMB, evaluating their true value, optimal applications, and limitations.

Creatine Monohydrate

Mechanism of Action

Creatine’s role in muscle energy metabolism:

ATP (energy molecule) → ADP + energy
         ↑
      Creatine phosphate (PCr) replenishment
         ↑
     Creatine supplementation

Creatine increases the creatine phosphate (PCr) pool, extending rapid ATP resynthesis and supporting high-intensity, short-duration exercise.

Scientific Evidence

IOC-recognized supplement. Over 500 studies published:

Exercise Type	Effect Size	Evidence Strength
Short sprints (10-30 sec)	5-15%	★★★★★
Repeated sprints	5-10%	★★★★★
Strength training	5-8%	★★★★★
Moderate-intensity intervals	2-4%	★★★★
Pure endurance (>90 min)	<2%	★★

For endurance athletes (long-distance cycling), creatine’s effects are limited.

Supplementation Protocols

Full Loading

Days 1-5: 20g/day (divided into 4 doses of 5g each)
         or 0.3g/kg/day
After: 5g/day maintenance (or 0.03g/kg/day)

Effect: Rapid saturation of muscle creatine (5-7 days)

Gradual (No Loading)

3g/day for 5 weeks
      ↓
Muscle creatine concentration rises progressively
      ↓
Same effect as above, but gentler, without initial side effects

Individual Response

Creatine responders vs. non-responders:

• Responders (~70%): Increased muscle creatine, performance ↑3-15%
• Non-responders (~30%): No significant increase in muscle creatine, no performance improvement

Determining factors:

• Baseline creatine levels (vegetarians respond better)
• Muscle fiber type composition (fast-twitch dominant respond better)
• Training status

Safety

Long-term supplementation (>5 years) has sufficient safety data:

• Creatinine (kidney function marker): No significant impact
• Liver function: No impact
• Athletic performance: Continued improvement

⚠️ Contraindications:

• Patients with renal impairment
• Dehydrated states (increased kidney burden)

Value for Endurance Athletes

Limited. Recommended scenarios:

• Events with multiple sprint or climb segments
• Events requiring repeated high-intensity output
• Mountain biking (vs. pure endurance road racing)

Beta-Alanine

Mechanism of Action

Beta-alanine synthesizes carnosine and anserine, which are the primary intramuscular pH buffering substances:

High-intensity exercise
   ↓
Lactate accumulation → Muscle pH↓
   ↓
Actin-myosin interaction↓
   ↓
Contractile force↓, Fatigue↑

Carnosine supplementation
   ↓
Increased muscle pH buffering capacity
   ↓
Delayed fatigue, maintained high-intensity output

Scientific Evidence

Exercise Type	Exercise Duration	Effect Size	Evidence Strength
High-intensity intervals	1-10 min	2-3%	★★★★
Moderate-to-high intensity	60-240 sec repeated	2-5%	★★★★
Endurance exercise	>30 min	<1%	★★

Effects are limited for long-distance endurance athletes but may benefit endurance events with high-intensity segments (e.g., mountain cycling races).

Supplementation Protocol

Effective dose: 3-6g/day
Supplementation period: 4-8 weeks
    ↓
Carnosine levels accumulate slowly
    ↓
Effects appear from week 2, peak at weeks 4-6

Split dosing: Better absorption
Example: 1.5g × 2 times/day

Side Effects

Beta-alanine’s unique side effect:

• Paresthesia (tingling in extremities): 30% of athletes
  • Onset: 15-30 minutes after ingestion
  • Intensity: Mild to moderate
  • Duration: 30-60 minutes
  • Harmless, but noticeably uncomfortable
  • Solution: Split doses, or take with food

Application for Endurance Athletes

Limited value. Application scenarios:

• Events with multiple high-intensity climbs
• Sprint finishes (final 15 minutes of high intensity)
• Multi-day races requiring sustained high intensity daily

HMB (β-Hydroxy-β-Methylbutyrate)

Mechanism of Action

HMB is a leucine metabolite involved in regulating muscle protein synthesis and breakdown:

HMB
  ↓
Activates mTOR (muscle growth signaling)
  ↓
Muscle protein synthesis↑

HMB
  ↓
Downregulates the ubiquitin-proteasome pathway
  ↓
Muscle breakdown↓ (especially during energy deficit)

Scientific Evidence

Evidence strength: weak to moderate (compared to creatine and caffeine).

Population	Training Type	Effect	Evidence
Elite athletes	Strength training	None/minimal	★★
Older adults (65+)	Resistance training	Muscle mass ↑5-8%	★★★
Strength athletes	High-intensity	None/minimal	★★
Endurance athletes	Endurance training	No effect	★

Recommended Dosage

Effective dose: 3-5g/day (divided into 3 doses)
Supplementation period: 2-8 weeks
   ↓
Effects (if any): Typically appear by week 4
Marginal benefit: Effects typically saturate at 2-3g

Individual Response

HMB response varies greatly:

• Best responders: Older adults or strength athletes early in training
• Poor responders: Elite trained athletes, endurance athletes

Cost-Benefit Analysis

• Monthly cost: NT$200-400 (3-5g/day)
• Expected benefit (endurance athletes): Minimal to none
• Recommendation rating: ⭐ (not recommended)

Supplement Comparison: Priority

Priority for Endurance Cyclists

Priority 1 (most important, strongest evidence):
  1. Carbohydrate supplementation
  2. Protein supplementation
  3. Electrolyte supplementation
  4. Caffeine
  5. Nitrate (beetroot)

Priority 2 (limited but potentially helpful):
  6. Beta-alanine (only for high-intensity segments)

Priority 3 (very limited effect for endurance):
  7. Creatine (<1% effect for endurance)
  8. HMB (no evidence to support)

Integrated Supplementation Strategy

Example Seasonal Nutrition Plan (Cycling):

Foundation (year-round):
- Carbohydrates, protein, electrolytes (adjusted to training)
- Multivitamins
- Essential minerals (iron, magnesium)

4-6 weeks pre-race (event-specific):
+ Caffeine sensitivity reset (discontinue daily coffee)
+ Beetroot nitrate supplementation (if a good responder)
+ Beta-alanine (if the event includes high-intensity climbs)

1 week pre-race:
+ Stop any new supplements
+ Carbohydrate loading
+ Electrolyte optimization
+ Taper training

Race day:
+ Caffeine (60-90 minutes pre-race)
+ Beetroot (if planned)
+ Standard fueling (carbohydrates + electrolytes)

Practical Case Studies

Case 1: Professional Road Cyclist (Long-Distance Endurance Race)

Assessment:

• Creatine: Not recommended (endurance-dominant)
• Beta-alanine: Not recommended (pure endurance)
• HMB: Not recommended (no effect)
• Caffeine: Recommended (2-4% improvement)
• Nitrate: Recommended (trial, 1-2% improvement)

Case 2: Amateur Mountain Biker (Including Multiple Climbs)

Assessment:

• Creatine: Potentially helpful (multiple high-intensity efforts)
• Beta-alanine: Potentially helpful (high intensity during climbs)
• HMB: Not recommended (no evidence)
• Caffeine: Recommended
• Nitrate: Recommended

Avoiding Supplement Pitfalls

Common Misconceptions

1. More = Better

   • Most supplements have a dosage ceiling; exceeding it provides no benefit
   • Overdosing may lead to side effects

2. Everyone Responds the Same Way

   • Individual variation is significant
   • Train during training, not during competition

3. Supplements Replace Foundational Nutrition

   • Supplements complement, not replace
   • Optimize food-based nutrition first

4. New = Better

   • Scientific evidence takes time to accumulate
   • Stick with supplements backed by sufficient evidence

Practical Recommendations

1. Check Evidence Strength: Prioritize supplements with strong supporting evidence
2. Consider Individual Characteristics: Supplement effects vary by sport discipline
3. Test During Training: Do not experiment with supplements during competition
4. Cost-Benefit Analysis: Ensure a return on investment
5. Avoid Overdosing: Follow recommended dosages
6. Evaluate Regularly: Track the relationship between supplements and performance

Supplements are not a magic bullet. For endurance athletes, training, nutrition (food), and recovery always take priority; supplements are merely the icing on the cake. Through rational assessment, athletes can make evidence-based supplement decisions.

Related Reading

• The Science of Sports Supplements: Creatine, Beta-Alanine, and Nitrate
• Creatine vs HMB: Supplement Choices and Evidence Strength Comparison for Endurance Athletes
• Sports Supplement Science Explained: The Impact of Caffeine, Beta-Alanine, and Creatine on Cycling Performance
• Beta-Alanine and Sodium Bicarbonate: An Update on the Scientific Evidence for Legal Ergogenic Aids