Supplements for HIIT Performance: What Works and What Doesn't

The supplement industry presents a dizzying array of products claiming to enhance athletic performance, build muscle, boost energy, and accelerate recovery. For HIIT enthusiasts seeking every possible advantage, the temptation to try various supplements is understandable. However, not all supplements deliver on their promises, and some provide negligible benefits despite significant costs. This evidence-based guide separates truly effective supplements from marketing hype, helping you make informed decisions about which products might genuinely enhance your HIIT performance and recovery.

The Supplement Landscape: Navigating Claims vs. Reality

The global sports nutrition market exceeds $20 billion annually, with new products constantly emerging with bold claims and flashy packaging. Marketing often outpaces science in this industry, creating confusion about what actually works. Unlike prescription medications, supplements undergo minimal regulatory oversight before reaching consumers, placing the responsibility on you to evaluate their efficacy and safety.

When assessing any supplement, consider three fundamental questions: Is there credible scientific evidence supporting its claimed benefits? Is the supplement relevant to your specific training goals? And does the potential benefit justify the cost? This framework helps filter marketing hype from genuine performance enhancers.

Additionally, understanding the difference between ergogenic aids (those directly enhancing performance) and recovery supplements (those supporting adaptation between workouts) allows for more strategic supplement selection. HIIT's unique physiological demands—combining high power output with limited recovery periods—create specific nutritional requirements that some supplements may address more effectively than others.

Tier 1: Evidence-Backed Supplements for HIIT

These supplements have substantial scientific support specifically relevant to high-intensity interval training, with multiple well-designed studies demonstrating meaningful benefits for performance, recovery, or both.

Creatine Monohydrate

Creatine stands as perhaps the most thoroughly researched and validated performance supplement available. Its primary mechanism involves increasing phosphocreatine stores in muscles, enhancing ATP regeneration during high-intensity efforts—precisely the type of activity that defines HIIT workouts.

For HIIT specifically, creatine offers several evidence-backed benefits:

• Increased power output during short, intense efforts (5-15% improvement in many studies)
• Enhanced recovery between intervals, allowing for more total work in a session
• Improved training volume capacity over time, potentially accelerating fitness adaptations
• Modest support for muscle protein synthesis, complementing the muscle-building stimulus of HIIT

The standard protocol involves loading with 20g daily (divided into 4-5 doses) for 5-7 days, followed by a maintenance dose of 3-5g daily thereafter. However, simply taking 3-5g daily from the start also achieves full saturation, just more gradually (over approximately 3-4 weeks rather than one week).

Creatine monohydrate remains the most studied and cost-effective form, with alternative forms (ethyl ester, HCL, buffered, etc.) showing no reliable superiority despite higher prices. For most HIIT practitioners, the modest investment in basic creatine monohydrate provides exceptional return through measurable performance enhancements.

Caffeine

Caffeine deserves its reputation as one of the most reliable performance enhancers, with particular relevance to HIIT through multiple mechanisms:

• Central nervous system stimulation, reducing perceived effort during high-intensity intervals
• Enhanced calcium release within muscle fibers, potentially improving contraction force
• Increased fat oxidation, which may spare glycogen during longer HIIT sessions
• Improved focus and alertness, valuable during technically demanding intervals

For optimal HIIT performance, evidence suggests 3-6mg of caffeine per kilogram of body weight taken 30-60 minutes before training. For a 70kg individual, this translates to approximately 200-400mg—the equivalent of 2-4 cups of coffee.

Pre-workout supplements typically contain caffeine along with other ingredients, but simple caffeine sources like coffee or caffeine tablets offer similar performance benefits at a fraction of the cost. Importantly, caffeine's effects diminish with habitual use, so strategic timing (using it only before particularly challenging sessions) may maximize its benefits.

Tolerance and sensitivity vary substantially between individuals. Those with high blood pressure, anxiety disorders, or sleep disturbances should exercise particular caution with caffeine supplementation and potentially opt for lower doses.

Beta-Alanine

Beta-alanine has emerged as a valuable supplement for activities lasting 1-4 minutes—a duration that aligns with many HIIT protocols. It functions by increasing muscle carnosine levels, enhancing the muscle's ability to buffer hydrogen ions that contribute to fatigue during high-intensity exercise.

Research indicates beta-alanine particularly benefits:

• Exercise lasting 60-240 seconds (the sweet spot for many HIIT intervals)
• Activities where muscular acidosis becomes a limiting factor
• Training involving repeated high-intensity efforts with limited recovery

Typical dosing involves 3.2-6.4g daily, taken in divided doses (1.6g at a time) to minimize the harmless but sometimes uncomfortable tingling sensation (paresthesia) that accompanies larger doses. Consistent supplementation for at least 4-6 weeks is necessary to significantly increase muscle carnosine levels and observe performance benefits.

For HIIT specifically, beta-alanine appears most beneficial for protocols involving longer intervals (60+ seconds) at near-maximal intensity. Shorter intervals (under 30 seconds) or lower-intensity protocols may not create sufficient muscular acidosis for beta-alanine to provide meaningful benefits.

Protein Supplements (Whey, Casein, Plant-Based)

While not performance enhancers in the traditional sense, protein supplements play a crucial role in the recovery and adaptation processes following HIIT sessions. High-quality protein sources provide the amino acid building blocks necessary to repair exercise-induced muscle damage and support the muscle-building potential of interval training.

For HIIT practitioners, protein supplementation offers several benefits:

• Convenient post-workout nutrition when whole food options aren't immediately available
• Precise dosing to meet specific protein targets
• Various digestion rates (fast for whey, slow for casein) to address different nutritional timing needs
• Plant-based options for those avoiding animal products

Research suggests consuming 20-40g of high-quality protein within 2 hours after HIIT training optimizes the muscle protein synthetic response. The exact amount depends on individual factors including body size, overall protein intake, and specific training goals.

Among protein options, whey provides the highest leucine content and rapid absorption, making it particularly effective post-workout. Casein's slower digestion makes it valuable before longer fasting periods, such as before sleep. Plant-based proteins (particularly blends combining rice, pea, or hemp sources) can approach the amino acid profile of animal proteins when properly formulated.

For general recovery support, any protein source that helps you meet your overall daily protein target (typically 1.6-2.2g per kg of body weight for active individuals) will provide benefits. The convenience factor often justifies the modest cost of protein supplements compared to whole food equivalents.

Tier 2: Promising Supplements with Moderate Evidence

These supplements show potential benefits for HIIT performance or recovery, with some supporting research but either fewer studies or less consistent results than Tier 1 supplements.

Sodium Bicarbonate (Baking Soda)

Sodium bicarbonate functions as an extracellular buffer, potentially delaying fatigue during high-intensity exercise by helping neutralize the acid buildup that occurs during anaerobic metabolism—a key factor in HIIT performance.

Research indicates potential benefits including:

• Delayed onset of fatigue during repeated high-intensity efforts
• Increased total work capacity during interval sessions
• Enhanced ability to maintain power output in later intervals

Effective dosing typically involves 0.2-0.3g per kg of body weight taken 60-90 minutes before exercise. However, gastrointestinal discomfort represents a significant limitation, with many users experiencing nausea, cramping, or diarrhea, particularly at higher doses.

To minimize digestive issues, consider spreading the dose over 15-30 minutes, taking it with ample water, or reducing to a more tolerable level (starting with 0.1g/kg and gradually increasing). Some athletes find mixing with a small amount of carbohydrate (like fruit juice) helps reduce GI symptoms.

For HIIT applications, sodium bicarbonate appears most valuable for sessions involving repeated near-maximal efforts with limited recovery—precisely the conditions that create significant metabolic acidosis. The low cost makes experimentation reasonable for those who don't experience prohibitive GI distress.

Beetroot Juice/Nitrates

Dietary nitrates, particularly concentrated in beetroot juice, enhance nitric oxide production in the body. This vasodilator improves blood flow, potentially enhancing oxygen and nutrient delivery to working muscles while reducing the oxygen cost of exercise.

For HIIT performance, nitrate supplementation shows several promising effects:

• Reduced oxygen cost of exercise at submaximal intensities (improved efficiency)
• Enhanced tolerance for high-intensity efforts
• Potentially improved recovery between intervals through better blood flow

Research suggests consuming approximately 6-12 mmol of nitrates (typically 300-600ml of beetroot juice or 2-3 whole beets) 2-3 hours before exercise provides optimal benefits. Commercial concentrated beetroot shots offer a more convenient alternative to whole juice.

Response to nitrate supplementation varies significantly between individuals, with some showing substantial performance improvements while others experience minimal effects. Evidence suggests those with higher training status may benefit less than recreational athletes, possibly due to already-enhanced nitric oxide production from regular training.

For HIIT applications, nitrates appear most beneficial for sessions lasting 12-30 minutes with intervals in the 1-3 minute range—durations where the improved exercise efficiency would provide meaningful advantages.

Citrulline Malate

Citrulline malate combines L-citrulline (an amino acid) with malate (an organic salt), potentially enhancing performance through increased arginine and nitric oxide levels, improved ammonia clearance, and enhanced aerobic energy production.

Research, though less extensive than for the Tier 1 supplements, suggests potential benefits including:

• Increased training volume capacity (more total repetitions across multiple sets)
• Reduced post-exercise muscle soreness
• Enhanced blood flow, potentially improving nutrient delivery and waste product removal

Effective dosing typically involves 6-8g taken 60 minutes before exercise. Like sodium bicarbonate, gastrointestinal discomfort represents a potential side effect for some users, though generally less severe.

For HIIT applications, citrulline malate appears most valuable for resistance-based intervals or circuit training formats where total volume represents a key performance metric. The relatively moderate cost and promising early research make it worth considering, particularly for those performing resistance-based HIIT formats.

Electrolyte Supplements

Electrolyte supplementation becomes increasingly relevant for HIIT sessions conducted in hot environments, lasting beyond 30-45 minutes, or for individuals with high sweat rates or salty sweat. The primary electrolytes lost through sweat—sodium, chloride, potassium, magnesium, and calcium—play crucial roles in muscle contraction, nerve function, and fluid balance.

For some HIIT practitioners, electrolyte supplementation may provide benefits including:

• Maintained hydration status through improved fluid retention
• Potentially reduced cramping during longer training sessions
• Supported nervous system function during high-output exercise

Individual needs vary dramatically based on sweat rate, sweat composition, and environmental conditions. Rather than following standard recommendations, consider the specific conditions of your training: longer sessions, hot environments, and noticeable salt residue on clothing after workouts all suggest higher electrolyte needs.

For most HIIT formats lasting under 45 minutes in temperature-controlled environments, plain water hydration suffices. For longer sessions, particularly in heat, adding electrolytes becomes increasingly important—either through commercial supplements or simple additions like a pinch of salt and squeeze of lemon to water.

Tier 3: Limited Evidence Supplements

These supplements have theoretical mechanisms that might benefit HIIT performance, but currently lack substantial evidence specifically supporting their use for this training modality.

Branched-Chain Amino Acids (BCAAs)

BCAAs (leucine, isoleucine, and valine) represent some of the most heavily marketed supplements in the fitness industry. While these essential amino acids play important roles in muscle protein synthesis and energy production, the benefits of supplementation for individuals already consuming adequate dietary protein remain questionable.

The theoretical benefits for HIIT include:

• Reduced muscle protein breakdown during training
• Decreased post-exercise muscle soreness
• Additional energy substrate during prolonged exercise

However, current research suggests that for individuals consuming sufficient total protein (1.6-2.2g/kg/day), BCAA supplementation provides minimal additional benefits. Complete protein sources (including whey, meat, eggs, etc.) already contain BCAAs in their naturally occurring ratios, making isolated BCAA supplements largely redundant for those with adequate protein intake.

The exception might be those training in a fasted state or individuals following strict plant-based diets with challenges meeting leucine thresholds. In these specific scenarios, BCAAs might provide theoretical benefits, though evidence remains limited.

Given their relatively high cost compared to complete protein sources, BCAAs represent a questionable investment for most HIIT practitioners unless specific circumstances (like fasted training) apply to your situation.

Glutamine

Glutamine, the most abundant amino acid in the body, plays roles in immune function, intestinal health, and acid-base balance. Supplement manufacturers often claim benefits for recovery and immune support, particularly relevant to high-intensity training that can temporarily suppress immune function.

The theoretical benefits include:

• Preserved immune function during periods of intense training
• Reduced muscle soreness and improved recovery
• Support for gut health, potentially important during high-stress training periods

However, research has consistently shown limited ergogenic benefits from glutamine supplementation in healthy, well-nourished individuals. The body efficiently produces glutamine, and dietary protein provides additional amounts, typically meeting requirements except in extreme circumstances.

For HIIT specifically, evidence doesn't support glutamine as a performance enhancer or recovery accelerator for most individuals. Exceptions might include those undergoing extremely high training volumes or individuals with compromised gut health, where some evidence suggests potential benefits.

Given the lack of compelling evidence and relatively high cost, glutamine supplementation shouldn't be prioritized over more established options for most HIIT practitioners.

HMB (Beta-hydroxy beta-methylbutyrate)

HMB, a metabolite of the amino acid leucine, has been proposed to enhance recovery and reduce muscle protein breakdown, potentially relevant for the muscle-damaging nature of high-intensity training.

The theoretical benefits include:

• Reduced muscle protein breakdown during training
• Decreased exercise-induced muscle damage
• Enhanced recovery between training sessions

Early research showed promising results, but more recent, higher-quality studies have demonstrated less impressive outcomes. Current evidence suggests HMB may provide modest benefits for those new to high-intensity training or during periods of caloric restriction, but limited advantages for experienced trainees following adequate nutrition practices.

Given its relatively high cost and inconsistent research results, HMB represents a lower-priority supplement for most HIIT practitioners, particularly those already consuming sufficient protein and using more established supplements.

Supplements to Avoid for HIIT

Some supplements marketed to fitness enthusiasts show little evidence of effectiveness or raise safety concerns, representing poor investments despite sometimes aggressive marketing.

"Proprietary Blends" Without Disclosed Dosages

Many pre-workout and "performance-enhancing" supplements list proprietary blends on their labels, disclosing the ingredients but not the specific amounts of each. This practice prevents consumers from knowing if efficacious doses of active ingredients are present or if the product primarily contains inexpensive fillers.

For example, a pre-workout might list "Energy and Performance Blend (4,500mg)" containing caffeine, beta-alanine, creatine, and several other ingredients. Without knowing the individual amounts, you can't determine if you're receiving the evidence-based doses (e.g., 3-5g of creatine, 3.2-6.4g of beta-alanine) required for benefits.

Instead, choose products with fully disclosed ingredient amounts, allowing you to verify that active ingredients appear in scientifically supported doses. Better yet, purchase individual ingredients with established benefits and combine them yourself for a customized, cost-effective approach.

Fat Burners and Thermogenics

Fat burner supplements typically combine stimulants (caffeine, yohimbine, synephrine) with various herbal extracts, claiming to increase metabolism and enhance fat oxidation during exercise. While some ingredients show modest effects in isolation, the magnitudes rarely justify the costs or potential side effects.

Most "fat-burning" effects from these supplements come from their caffeine content, which can indeed slightly increase energy expenditure and fat oxidation. However, purchasing caffeine alone provides the same benefit at a fraction of the cost without additional untested ingredients.

For HIIT specifically, the high-intensity nature of the training already maximizes caloric expenditure and creates powerful metabolic effects. The marginal additional benefit from thermogenic supplements pales in comparison to consistent training and proper nutrition.

Testosterone Boosters

Over-the-counter testosterone boosters typically contain ingredients like tribulus terrestris, fenugreek, D-aspartic acid, and various vitamins and minerals. Despite claims of increasing natural testosterone production and enhancing performance, research consistently shows these products fail to meaningfully impact hormone levels in healthy individuals.

Studies measuring actual testosterone levels (rather than subjective measures) generally show no significant differences between supplement and placebo groups. The few exceptions typically involve correcting deficiencies (like vitamin D or zinc in deficient individuals) rather than boosting already-normal levels.

Given their high cost and lack of proven benefits, testosterone boosters represent one of the poorest supplement investments for HIIT practitioners seeking performance enhancement.

Supplement Timing and Combinations for HIIT

Strategic timing and thoughtful combinations of evidence-based supplements may maximize benefits for HIIT performance and recovery.

Pre-Workout Timing Strategy

For optimal pre-HIIT supplementation:

• Caffeine: 30-60 minutes before training (3-6mg/kg body weight)
• Beetroot juice/nitrates: 2-3 hours before training (300-600ml)
• Sodium bicarbonate: 60-90 minutes before training (0.2-0.3g/kg body weight)
• Citrulline malate: 60 minutes before training (6-8g)

This timing accounts for each supplement's pharmacokinetics—when it reaches peak blood levels and begins exerting its primary effects. For convenience, you might standardize to 60 minutes pre-workout for all supplements, which provides near-optimal timing for most options.

For those sensitive to stimulants, consider non-stimulant pre-workout options focusing on nitric oxide enhancers (beetroot, citrulline) and buffering agents (sodium bicarbonate) rather than caffeine-based products, particularly for afternoon or evening sessions.

Daily Supplement Strategy

Some supplements require consistent daily use rather than pre-workout timing:

• Creatine: 3-5g daily, timing less important than consistency
• Beta-alanine: 3.2-6.4g daily in divided doses (1.6g at a time)
• Protein: Distributed throughout the day, with one serving typically after training

These supplements work through cumulative effects, building up in the body over time rather than providing acute benefits. Consistency matters more than specific timing, though taking them with meals may improve absorption and reduce potential GI discomfort.

Consider creating a simple daily routine—perhaps taking creatine and one beta-alanine dose with breakfast, another beta-alanine dose with lunch, and protein after training—to establish consistent habits that ensure you receive the benefits of these evidence-based supplements.

Cost-Effective Combinations

For those with budget constraints, prioritize supplements with the strongest evidence and most direct relevance to your specific HIIT format:

Basic Foundation (~$30-40/month):

• Creatine monohydrate (3-5g daily)
• Caffeine (200-400mg before challenging sessions)
• Protein supplement (as needed to meet daily protein targets)

Expanded Support (~$50-70/month):

• All foundation supplements
• Beta-alanine (3.2-6.4g daily)
• Electrolytes (for longer sessions or hot environments)

Comprehensive Approach (~$80-100/month):

• All previous supplements
• Beetroot juice or nitrate supplement (for key sessions)
• Citrulline malate (6-8g before longer or volume-focused sessions)

This tiered approach allows you to start with the most evidence-backed, cost-effective options and expand based on results, specific needs, and budget availability.

Safety Considerations and Quality Assurance

Supplement safety concerns extend beyond effectiveness to include contamination risks, proper dosing, and potential interactions with medications or existing health conditions.

Third-Party Testing

The supplement industry's limited regulation creates quality assurance challenges. Third-party testing organizations provide independent verification of product contents, confirming that supplements:

• Contain the ingredients listed on the label
• Provide the claimed amounts of active ingredients
• Are free from harmful contaminants like heavy metals or banned substances

Look for certifications from organizations like:

• NSF Certified for Sport
• Informed Choice/Informed Sport
• USP Verified
• BSCG (Banned Substances Control Group)

These certifications are particularly important for competitive athletes subject to drug testing, as supplement contamination has led to numerous positive tests and subsequent suspensions despite athletes' lack of intention to use prohibited substances.

Pre-Existing Health Conditions

Several common supplements warrant caution for individuals with specific health conditions:

• Caffeine: May exacerbate anxiety disorders, sleep problems, heart arrhythmias, and hypertension
• Creatine: Requires adequate hydration; some theoretical concerns for those with kidney issues
• Sodium bicarbonate: Potentially problematic for individuals with hypertension or on sodium-restricted diets
• Pre-workout blends: Often contain multiple stimulants that may interact with medications or health conditions

Always consult healthcare providers before beginning supplement regimens if you have pre-existing health conditions or take prescription medications. The performance benefits never outweigh potential health risks, particularly for recreational athletes.

Pregnancy, Nursing, and Special Populations

Most performance-enhancing supplements lack adequate safety research for pregnant or nursing individuals. Generally, only basic supplements with established safety profiles (like protein) are recommended during these periods, with most ergogenic aids best avoided without specific medical approval.

Similarly, adolescent athletes should focus primarily on developing proper nutrition habits rather than supplementation. Basic protein supplements may be appropriate in certain circumstances, but stimulants and other performance enhancers are generally unnecessary and potentially concerning for developing individuals.

Using Peak Interval to Maximize Supplement Benefits

The effectiveness of performance-enhancing supplements depends not just on their inherent properties but on how well they align with your workout structure. Peak Interval's customizable timing features allow you to design HIIT sessions that maximize the benefits of specific supplements.

For caffeine and other pre-workout stimulants, program high-intensity intervals to coincide with peak blood levels—typically 30-60 minutes after consumption. The app allows you to create workouts with gradually increasing intensity during this window, matching your physiological state with appropriate work demands.

Creatine supplementation particularly enhances performance during short, maximal-effort intervals with brief recovery periods. Design workouts with 20-30 second all-out efforts followed by 60-90 second recoveries to leverage creatine's enhancement of the phosphocreatine energy system.

Beta-alanine benefits longer high-intensity intervals through improved buffering capacity. Program intervals in the 60-120 second range at near-maximal intensity to utilize the enhanced performance capability this supplement provides.

For supplements that potentially enhance recovery between intervals, like citrulline malate or beetroot juice, consider designing sessions with shorter rest periods than normal, potentially allowing you to accomplish more total work in the same training time.

The app's ability to save multiple workout templates allows you to create specific protocols optimized for different supplement strategies—perhaps one template maximizing creatine benefits, another leveraging beta-alanine's effects, and a third designed for general performance without specific supplement considerations.

Beyond Supplements: Foundational Priorities

While certain supplements offer legitimate performance benefits, they represent a small component of the overall picture. Before investing in supplements, ensure these foundational elements are addressed:

Nutrition Fundamentals

No supplement regime compensates for poor underlying nutrition. Prioritize:

• Adequate overall energy intake to support training demands
• Sufficient protein (1.6-2.2g/kg/day for most active individuals)
• Appropriate carbohydrate timing around workouts
• Fruits and vegetables providing essential micronutrients
• Adequate hydration before, during, and after training

These fundamental nutritional practices provide the foundation upon which supplement strategies can build. Without them, even the most evidence-backed supplements will provide minimal benefits.

Recovery Protocols

Similarly, basic recovery practices deliver greater benefits than most supplements:

• Sufficient sleep quantity and quality (7-9 hours for most adults)
• Appropriate training volume and intensity progression
• Strategic deload periods preventing overtraining
• Stress management techniques supporting overall recovery
• Proper warm-up and cool-down protocols

These fundamental recovery elements create the physiological environment in which adaptations occur. Supplements may enhance this process but cannot replace these foundational practices.

Training Program Design

Finally, properly structured HIIT programming provides benefits far exceeding what supplements can deliver:

• Appropriate work-to-rest ratios for your fitness level and goals
• Strategic progression of intensity, duration, and complexity
• Variety preventing plateaus while ensuring consistent overload
• Periodization allowing for both progress and recovery

The Peak Interval app provides the tools to implement these programming principles with precision, ensuring your fundamental training approach is optimized before adding supplemental ergogenic aids.

The Evidence-Based Approach to Supplement Selection

As you consider which supplements might enhance your HIIT performance, maintain a scientifically grounded perspective. Seek information from peer-reviewed research rather than marketing materials or anecdotal testimonials. Understand that individual response varies considerably—what works dramatically for one person may provide minimal benefits for another.

Approach new supplements with reasonable expectations and a methodical testing process. Introduce one supplement at a time, establish consistent use for the minimum effective period (several weeks for most options), and objectively assess results through performance metrics rather than subjective feelings.

Remember that supplements represent the final few percentage points of optimization after nutrition, training, and recovery fundamentals are established. They can provide meaningful benefits for dedicated trainees, but they cannot compensate for deficiencies in these foundational areas.

With this evidence-based approach, you can make informed decisions about which supplements deserve a place in your HIIT performance strategy, potentially enhancing your training results while avoiding unnecessary expenses on products unlikely to deliver meaningful benefits.