High‑Intensity Interval Training Enhances VO2max, Intermittent Endurance and Short‑Sprint Power in Trained Adolescent Athletes — Evidence and Practical Prescriptions for Coaches

Table of Contents

1. Key Highlights
2. Introduction
3. How the review defined HIIT and which studies were included
4. Quantified gains: cardiorespiratory outcomes
5. Jump and power: countermovement jump (CMJ)
6. Sprint performance: short vs. longer distances
7. Change‑of‑direction (COD) and repeated sprint ability (RSA)
8. Which HIIT formats drive which adaptations?
9. Age, competitive level, and other moderators — what matters
10. Practical programs: sample HIIT sessions and weekly templates
11. Integrating HIIT with strength, plyometrics, and technical training
12. Monitoring, safety and maturation considerations
13. Limitations of the evidence and directions for research
14. Translating effect sizes into practical expectations for coaches
15. How coaches should prioritize HIIT within annual plans
16. Practical checklist for implementing HIIT with adolescent athletes
17. Implications for policy and youth development programs
18. FAQ

Key Highlights

• A pooled analysis of 35 controlled trials (988 trained adolescent athletes) found that HIIT-based interventions produced moderate improvements in VO2max (SMD = 0.65), field-based intermittent endurance tests (SMD = 0.65), VIFT (30–15 IFT final velocity; SMD = 1.13), and ≤10 m sprint performance (SMD = -0.79). Smaller, but statistically significant, gains were observed for countermovement jump, ≥20 m sprint, and change-of-direction ability.
• Repeated sprint training (RST) protocols specifically improved repeated sprint ability (RSA) with a moderate effect (SMD = -0.70); subgroup analyses suggested greater field-test gains in athletes ≥16 years and better ≥20 m sprint responses at higher competitive levels (Tier 3). Evidence certainty varied across outcomes and many included trials had methodological limitations.

Introduction

Adolescent athletes are subject to rapid biological change and mounting training demands. Coaches and conditioning staff must prioritize training formats that deliver measurable gains in limited practice time while safeguarding development and recovery. High‑intensity interval training (HIIT) is one practical option: structured brief bouts of near‑maximal or supramaximal effort interspersed with recovery that can be executed in small time windows or embedded into sport sessions.

This systematic review and meta‑analysis pooled controlled trials that tested HIIT‑based interventions—running and sport‑specific, short and long intervals, sprint interval training (SIT), and repeated sprint training (RST)—in trained adolescent athletes (10–19 years old; McKay Tier 2–3). The review quantified effects across core fitness domains (VO2max, intermittent endurance tests including Yo‑Yo and the 20 m shuttle, 30–15 IFT final velocity, CMJ, sprinting at different distances, change‑of‑direction, and repeated sprint ability), explored moderators such as age and competitive level, and assessed certainty and risk of bias.

The findings offer actionable information for practitioners designing preseason and in‑season conditioning programs and clarify where HIIT yields the largest returns and where complementary methods remain necessary.

How the review defined HIIT and which studies were included

The authors included randomized and non‑randomized controlled trials where the experimental arm used clearly defined HIIT formats—interval‑type HIIT, SIT, RST, or sport‑specific HIIT—delivered as repeated high‑intensity work bouts with planned recovery. Studies were restricted to trained adolescent athletes (Tier 2 or Tier 3 by the McKay Participant Classification Framework), and comparators included regular sport training, continuous moderate‑intensity work, coordination or resistance training, or no additional training.

Key characteristics of the included trials:

• 35 studies, 988 athletes (male, female, and mixed samples)
• Sport distribution dominated by soccer (17 studies), but included basketball, handball, taekwondo, tennis, futsal, karate, cross‑country skiing, aerobic gymnastics, and volleyball
• HIIT type mix: RST (11), short‑interval HIIT (10), SIT (5), long‑interval HIIT (4), and mixed interval protocols (4)
• Primary modes: running‑based HIIT (24 studies) and sport‑specific HIIT (9 studies)
• Intervention duration: 4–12 weeks; frequency: 1–4 sessions/week; total sessions: 8–32
• Outcome tests reported most often: CMJ and COD (20 studies each), VO2max (16), 20 m sprint (11), Yo‑Yo IR1 (7), RSA (7), and 30–15 IFT (5)

Risk of bias: most trials (31/35) had “some concerns”; four were judged high risk. Common limitations related to unclear randomization reporting and lack of blinding—typical issues for exercise trials.

Quantified gains: cardiorespiratory outcomes

Cardiorespiratory capacity showed some of the most consistent improvements.

• VO2max: 16 studies (522 participants) pooled to SMD = 0.65 (95% CI 0.46 to 0.83), p < 0.001, I² = 0%. Interpretation: a moderate effect favoring HIIT over non‑HIIT comparators with low between‑study heterogeneity.
• Field‑based intermittent endurance tests (Yo‑Yo IR1, Yo‑Yo IR2, 20 m shuttle): 9 studies (288 participants) pooled to SMD = 0.65 (95% CI 0.07 to 1.23), p = 0.028, I² = 79.4% — a moderate pooled effect but high heterogeneity reflecting test and protocol differences.
• VIFT (30–15 IFT final velocity): 5 studies (153 participants) produced a largeish pooled SMD = 1.13 (95% CI 0.63 to 1.63), p < 0.001, I² = 42.5%.

What this means for practice

• HIIT reliably improves maximal and intermittent endurance indicators across trained adolescents. The greatest and most consistent gains were seen for VO2max and VIFT. While the Yo‑Yo and shuttle tests improved on average, variability across test types, ages, and protocols suggests practitioners should match test selection, training content, and athlete maturation when prescribing HIIT.
• VIFT improvements are especially relevant for team‑sport athletes because the test individualizes interval workloads and closely reflects intermittent running demands.

Why HIIT improves these metrics Physiological mechanisms include central adaptations (stroke volume and cardiac output) and peripheral changes (mitochondrial density, capillarization, oxidative enzyme activity), combined with metabolic adaptations that improve lactate handling and phosphagen resynthesis between high‑intensity efforts—attributes targeted by HIIT formats.

Jump and power: countermovement jump (CMJ)

Countermovement jump (CMJ) was reported in 20 studies (543 participants).

• Result: SMD = 0.44 (95% CI 0.13 to 0.74), p = 0.004, I² = 62.7%. Effect size interpreted as small, with moderate-to-high heterogeneity.

Interpretation and coaching implications

• HIIT produced modest improvements in jump height/power. Running‑based HIIT and RST produce repeated explosive actions and high neuromuscular demand that can transfer to CMJ to some degree; however, conditioned adolescent athletes often require targeted plyometric or strength training to produce larger, sport‑relevant gains in vertical power.
• For athletes whose primary objective is to raise CMJ substantially (e.g., volleyball players, basketball players in roles emphasizing vertical output), combine HIIT with structured resistance or plyometric blocks.

Real‑world example

• A club adds two weeks of short‑interval HIIT during preseason and observes improved match fitness and a small uptick in CMJ. When the club supplements with an 8‑week combined strength and plyometric block, vertical jump gains become more pronounced and durable.

Sprint performance: short vs. longer distances

Sprint outcomes displayed distance‑dependent effects.

• ≤10 m sprint (acceleration): 6 studies (165 participants) — SMD = -0.79 (95% CI -1.26 to -0.32), p = 0.001, I² = 50.1%. Moderate effect favoring HIIT with notable heterogeneity.
• ≥20 m sprint (maximal speed phases): 18 studies (423 participants) — SMD = -0.28 (95% CI -0.47 to -0.08), p = 0.005, I² = 0%. Small but significant improvement.

Interpretation

• HIIT, especially running‑based short‑sprint and RST formats, transfers well to acceleration (≤10 m). Acceleration depends strongly on horizontal force production, rate of force development, and neuromuscular coordination—qualities targeted by repeated short sprints common to HIIT drills.
• Improvements at ≥20 m—where maximal velocity mechanics and stride efficiency increasingly matter—were smaller. Maximal speed benefits typically require specific exposure to high‑velocity running with appropriate over‑speed/ resisted sprinting, technical work, and targeted strength training.

Subgroup signal: competitive level mattered for ≥20 m sprint

• Tier 3 athletes (higher competitive level) showed significant gains (SMD = -0.47), while Tier 2 did not, suggesting higher‑level athletes may convert HIIT exposure to top‑end speed more readily—possibly because of more advanced technique and higher baseline mechanical capacities.

Practical takeaway

• Use HIIT to efficiently develop acceleration and short‑sprint repeatability. For maximal velocity improvements, include dedicated sprint sessions, resisted sprinting, and maximal velocity technical work.

Change‑of‑direction (COD) and repeated sprint ability (RSA)

Change‑of‑direction (COD)

• 20 studies (550 participants): SMD = -0.54 (95% CI -0.72 to -0.37), p < 0.001, I² = 0%. Small-to-moderate improvement in COD time.

Interpretation

• Gains likely reflect improved braking and re‑acceleration capacity, neuromuscular coordination, and agility under fatigue. COD, however, depends on eccentric strength, technical footwork, and task‑specific mechanics; therefore, HIIT alone yields modest gains. Best results arise when COD‑specific drills or strength/plyometric components are included alongside HIIT.

Repeated sprint ability (RSA)

• Analysis included only RST protocols (7 studies, 208 athletes): SMD = -0.70 (95% CI -1.02 to -0.39), p < 0.001, I² = 12.7%.

Interpretation

• RST produced moderate improvements in RSA. Specificity explains much of the effect — RST mirrors the movement pattern, work durations, and recovery demands of RSA testing and match demands, yielding greater transfer than non‑specific HIIT formats.

Programming implication

• For sports where repeated sprinting determines performance (football, futsal, handball, taekwondo bouts), prioritize RST in conditioning phases when the goal is to enhance RSA.

Which HIIT formats drive which adaptations?

HIIT is not a single stimulus; adaptations map to protocol design.

• Long‑interval HIIT (e.g., 4 × 4 min at 90–95% HRmax, Helgerud style) targets central aerobic adaptations and supports VO2max improvements and endurance capacity. It fits preseason blocks when sport volume is lower and aerobic base building is desired.
• Short‑interval HIIT (e.g., 10–30 s work bouts at 90–130% MAS or VIFT with short rests) balances anaerobic and neuromuscular stress and appears useful for intermittent endurance and moderate jump/sprint transfer.
• Sprint Interval Training (SIT; 20–30 s all‑out bouts with long recoveries) drives anaerobic power and oxidative enzyme upregulation and may increase anaerobic capacity and sprint output.
• Repeated Sprint Training (RST; short maximal sprints with incomplete recovery, often shuttle formats) best targets RSA and acceleration. All RSA improvements in the pooled analysis stemmed from RST trials.

Matching format to outcome

• VO2max and VIFT: long and mixed interval HIIT showed consistent benefits.
• Intermittent endurance (Yo‑Yo): short‑interval HIIT and RST improve performance, but heterogeneity across tests cautions interpretation.
• Acceleration (≤10 m) and RSA: running‑based RST and short all‑out sprints are most effective.
• CMJ and COD: small transfers from HIIT occur; larger improvements require supplementary plyometric and strength training or COD‑specific drills.

Age, competitive level, and other moderators — what matters

The meta‑analysis tested prespecified moderators (sex, age, intervention duration, frequency, total sessions, competitive level, HIIT type, and mode). Most subgroup comparisons showed no statistically significant differences, but two exploratory signals emerged:

• Age and field‑based intermittent endurance tests: athletes ≥16 years improved in field tests (SMD = 1.07), while younger athletes (<16) did not show a pooled effect. Possible explanations include greater biological maturity, accumulated training exposure, and improved ability to tolerate and adapt to high training intensities.
• Competitive level and ≥20 m sprint: Tier 3 athletes showed significant gains; Tier 2 did not. Higher‑level athletes may have better technical and mechanical foundations to convert HIIT to maximal speed improvements.

Caveats

• Subgroup analyses were exploratory and underpowered; findings should guide hypothesis formulation rather than definitive practice changes.
• Interindividual maturation differences within an age band often exceed chronological age effects. Consider biological maturity, training history, and injury history when prescribing intensity loads.

Practical programs: sample HIIT sessions and weekly templates

The included trials used interventions spanning 4–12 weeks with 1–4 sessions per week and 8–32 total sessions. Below are representative, evidence‑anchored session templates that mirror protocols used in the literature and the outcomes they target.

Presession considerations

• Ensure athletes are familiar with sprint and change‑of‑direction mechanics.
• Monitor warm‑up, hydration, and recovery; use heart rate, VIFT, or perceived exertion to ensure appropriate intensity.
• Integrate HIIT sessions into the weekly microcycle to allow technical and strength work without excessive overload.

Preseason — aerobic and intermittent conditioning (8 weeks; 2 sessions/week)

• Session A (Long‑interval emphasis; Helgerud‑style)
  • Warm‑up: dynamic movement, 10–15 min
  • Main set: 4 × 4 min at 90–95% HRmax (or at target VIFT equivalent), 3 min active recovery (jog 50–60% HRmax)
  • Cool‑down and mobility
  • Goal: VO2max and sustained intermittent endurance improvements
• Session B (Short‑interval / SIT mixed)
  • Warm‑up
  • 6–8 × 30 s all‑out runs, 4–6 min passive or low‑intensity recovery (SIT style), or 2 × (8 × 30 s at 90–95% VIFT with 3 min between sets)
  • Goal: metabolic stress and neuromuscular stimulus

In‑season — match readiness and acceleration focus (6–8 weeks; 1–2 sessions/week)

• Session C (RST for RSA and acceleration)
  • Warm‑up: include sprint drills and COD practice
  • 3 sets of 6 × 20–35 m maximal sprints with 20–30 s passive recovery between reps; 3–4 min between sets
  • Progress number of reps over weeks (as in some successful trials)
  • Goal: acceleration, RSA, and short‑sprint repeatability
• Session D (High‑intensity intermittent with sport specificity)
  • Warm‑up
  • Small‑sided game or sport‑specific drills structured as HIIT: 4–6 bouts of 3–4 min of high‑intensity play matched to Yo‑Yo or VIFT targets with 2–3 min active recovery
  • Goal: integrate technical and tactical work with conditioning

Microcycle placement

• If match day (MD) is Saturday, schedule HIIT on MD‑5 or MD‑4 (preseason) and MD‑6/MD‑5 (in‑season) depending on overall load so players recover before MD‑1 technical session.

Progression and safety

• Start with lower volume and increase repetitions or intensity across weeks.
• Track session RPE and recovery markers (sleep, soreness). Adjust load for maturational and maturational variation.

Integrating HIIT with strength, plyometrics, and technical training

HIIT is efficient for aerobic and anaerobic endurance and short‑sprint capacity, but jump power, maximal speed, and technical COD mechanics benefit from targeted work:

• Strength training: scheduled 1–3 sessions per week depending on phase. For adolescents, emphasize movement quality, progressive overload, and relative strength (e.g., squat variations, Romanian deadlifts, hip hinge patterns). Strength blocks complement HIIT for force production and sprint mechanics.
• Plyometrics: short, high‑quality plyometric sessions (low volume, focus on landing mechanics and reactive strength) improve CMJ and transfer to acceleration when combined with strength work.
• COD training: include planned COD drills that emphasize deceleration, plant mechanics, and re‑acceleration, ideally combined with eccentric strength development.

Programming examples

• Combine RST days and plyometric/strength on separate days or in concurrent sessions with priority to strength in the morning and HIIT in the afternoon only in advanced athletes with adequate recovery.
• Use contrast sessions (e.g., heavy squats followed by short sprints) only for mature athletes under supervision.

Monitoring, safety and maturation considerations

Monitoring tools used in trials and recommended practice:

• Heart rate monitoring (HRmax targets used in many studies)
• VIFT or Yo‑Yo IR1 as individualized load markers for interval intensity prescription
• Session RPE scales to monitor internal load
• Performance tests (CMJ, 10–20 m sprints, COD drills) to track adaptation

Developmental caution

• Account for biological maturity: younger adolescents may need lower absolute loads and more gradual progression. The subgroup signal favoring ≥16‑year‑olds for some endurance gains underscores this.
• Avoid high cumulative load spikes. HIIT produces high neuromuscular and metabolic stress; integrate recovery strategies and limit high‑intensity sessions per week depending on total load.

Injury risk

• No widespread adverse events were reported across the included trials, but individual case reporting is limited. Ensure movement quality before maximal sprints and consider preparatory strength/plyometric phases.

Limitations of the evidence and directions for research

Key limitations highlighted by the review:

• Risk of bias: many trials had concerns around randomization reporting and lack of blinding—common but important limitations for exercise studies.
• Heterogeneity: especially for field‑based intermittent tests (Yo‑Yo vs. 20 m shuttle) where pooled I² reached 79.4%. Test differences, protocol diversity, athlete maturity, and sport context contribute to variability.
• Sport representation: soccer dominated the dataset, limiting generalizability to other sports with different movement profiles (e.g., gymnastics, combat sports).
• Small sample sizes for some outcomes and subgroup strata reduce statistical power to detect moderators.
• RSA results were derived exclusively from RST protocols; generalizing RSA improvements to other HIIT formats is not warranted.
• Publication and language bias: only English peer‑reviewed trials were included.

Research priorities

• Well‑powered randomized controlled trials across a broader range of sports and maturation stages.
• Direct comparisons of HIIT formats (short vs. long intervals, SIT vs. RST, sport‑specific vs. running HIIT) in adolescent athletes.
• Studies combining HIIT with structured strength/plyometric blocks to determine optimal sequencing for power and speed development.
• Dose‑response trials to identify minimal effective doses and upper limits for safety in youth.

Translating effect sizes into practical expectations for coaches

Standardized mean differences (SMDs) communicate magnitude relative to pooled variability. For practitioners:

• SMD ~0.6 (VO2max, VIFT, field tests) equates to moderate, meaningful fitness gains over 4–12 weeks that are likely to affect match performance in intermittent sports.
• SMD ~0.4 (CMJ) indicates small but detectable changes; expect modest vertical power gains from HIIT alone.
• SMD ~‑0.8 for ≤10 m sprints suggests a notable improvement in acceleration after running‑based HIIT or RST.
• Remember: absolute improvements depend on baseline level; highly trained athletes typically display smaller absolute gains but retain competitive advantages from targeted interventions.

How coaches should prioritize HIIT within annual plans

• Preseason (build phase): emphasize longer HIIT intervals and mixed formats to raise VO2max and intermittent endurance. Combine with strength foundation and technical drills.
• Early season (prepare to compete): integrate RST and short‑interval HIIT to sharpen acceleration and RSA while maintaining aerobic fitness. Keep volumes moderate and allow technical preparation.
• In‑season (maintenance and specificity): limit HIIT frequency (1–2 sessions/week), tailor to match load, and prioritize RST for sports demanding repeated high‑intensity efforts. Use sport‑specific HIIT to preserve technical and tactical work.
• Off‑season: light active recovery and lower intensity; reintroduce structured HIIT progressively.

Practical checklist for implementing HIIT with adolescent athletes

• Assess maturity and baseline fitness before prescribing intensity.
• Choose HIIT format based on the primary target:
  • VO2max/VIFT: long intervals (e.g., 4 × 4 min at 90–95% HRmax) or individualized VIFT prescriptions.
  • Acceleration and RSA: RST or short all‑out sprints with incomplete recovery.
  • Intermittent game fitness: sport‑specific HIIT or small‑sided games structured as intervals.
• Prescribe frequency consistent with trial evidence (1–3 sessions/week) and limit high‑intensity sessions in congested weeks.
• Monitor internal load (HR, RPE) and objective outputs (jump/sprint tests).
• Combine HIIT with strength and plyometric training when improvements in jump, maximal sprint, or COD are desired.
• Progress volume and intensity gradually, and individualize based on recovery and performance markers.

Implications for policy and youth development programs

National and club youth programs aiming to accelerate aerobic and intermittent fitness while preserving technical development can incorporate HIIT strategically:

• Use HIIT to replace some volume of lower‑intensity continuous training when time is constrained.
• Train staff to individualize interval intensity using VIFT or HR zones, and to plan microcycles that balance technical, tactical, and physical loads.
• Invest in systematic monitoring systems (simple RPE logs, periodic VIFT or Yo‑Yo tests) to guide progression.

FAQ

Q: Which HIIT format should I use to raise VO2max in adolescent athletes?
A: Long‑interval HIIT (e.g., multiple 4‑minute efforts at ~90–95% HRmax with active recovery) and mixed interval programs were associated with reliable VO2max gains. Individualize intensity using HR or VIFT and integrate strength work for best long‑term gains.

Q: Will HIIT alone make my athletes jump higher?
A: HIIT produces small improvements in CMJ, but larger, sport‑relevant gains typically require targeted strength and plyometric training in addition to HIIT.

Q: How many HIIT sessions per week are supported by the evidence?
A: Trials used 1–4 sessions/week, with most effective programs clustering at 1–3 sessions/week. Balance frequency with total training load and match schedules, and monitor recovery.

Q: Is RST better than other HIIT formats for repeated sprint ability?
A: Yes. Repeated sprint training—short maximal sprints with incomplete recovery—was specifically associated with moderate RSA improvements in the pooled trials. RSA gains should not be generalized to all HIIT types.

Q: At what age will athletes respond best to HIIT?
A: Subgroup signals suggest athletes ≥16 years showed larger improvements in field‑based intermittent tests. Maturity and training history influence responsiveness; tailor prescriptions to individual development rather than chronologic age alone.

Q: How should HIIT be combined with strength and technical work?
A: Schedule strength and plyometric blocks during preseason and separate heavy strength from maximal HIIT sessions to avoid acute interference. During in‑season, maintain lower volume strength work and prioritize recovery around match days. Sport‑specific HIIT or small‑sided games can concurrently develop technical skills and conditioning.

Q: Are the improvements durable after HIIT ceases?
A: The review focused on pre‑to‑post intervention effects; durability depends on continued exposure and maintenance programming. Periodic HIIT sessions and preservation of strength and sprint work support retention.

Q: Any safety concerns for adolescents doing HIIT?
A: When appropriately scaled and progressed, HIIT is safe for trained adolescents. Ensure movement competency, monitor load, consider maturity status, and avoid excessive frequency or volume spikes.

Q: How should coaches monitor HIIT intensity without high‑tech tools?
A: Use VIFT (30–15 IFT) to individualize running intensity, heart rate zones if available, and session RPE for internal load. Regular performance tests (10–20 m sprints, CMJ, Yo‑Yo) help track progress.

Q: Where does HIIT fit in talent development pathways?
A: HIIT offers time‑efficient conditioning for aerobic and intermittent performance and short‑sprint capacity. It should be a tool within a broader long‑term athletic development plan that includes strength, skill training, and age‑appropriate progressive overload.

Q: What are the strongest limitations of the current evidence?
A: Methodological issues (randomization, blinding), heterogeneity in tests and protocols, dominance of soccer samples, and limited sample sizes for some outcomes reduce certainty. More multi‑sport, high‑quality randomized trials are needed.

Q: Should small‑sided games replace HIIT?
A: Small‑sided games deliver combined technical and conditioning stimuli and sometimes produce similar aerobic adaptations. The choice depends on training goals: use sport‑specific games for integrated work and HIIT when precision dosing of intensity is required.

Q: How can I convert the review’s SMDs to practical expectations?
A: SMDs reflect effect magnitude relative to pooled variability. Expect moderate, practically meaningful gains in VO2max, VIFT, and short‑sprint acceleration after 4–12 weeks of well‑designed HIIT. Absolute gains will vary by baseline fitness—higher‑level athletes often show smaller absolute changes.

Q: Any final guidance for implementation?
A: Align HIIT format to the outcome you want. Use RST for RSA and acceleration, long intervals for VO2max, and short intervals for intermittent endurance. Combine HIIT with strength/plyometric work to broaden adaptations, progress load thoughtfully, and monitor recovery and maturation markers.