PMID 38275981

Research
All papers

High-Intensity Interval Training Combined with High-Load Strength Training Improves Aerobic Fitness, Match Goals and Match Result during the In-Season Period in Under-19 Soccer Players

Thomakos P, Spyrou K, Tsoukos A, Katsikas C, Bogdanis GC

Question

Does in-season high-load strength training combined with HIIT improve aerobic fitness and match outcomes more than a plyometric plus small-sided/tactical-game program in under-19 soccer players?

Summary

In two elite under-19 soccer teams, the team using weekly high-load strength plus running HIIT improved Yo-Yo IR2 performance, estimated VO2max, late-match scoring, and match results across the in-season period, while the comparison team using plyometrics and small-sided/tactical games did not show similar aerobic gains. The nonrandom two-team design limits causal certainty.

Methodology

  • Elite under-19 male soccer field players from two Greek Super League teams
  • 29 participants.
  • Gym strength training followed by running intervals.
  • Work intervals: 15 seconds at 110% vVO2max.
  • Recovery: 15 seconds passive recovery; 3 minutes between two 6-minute sets.
  • Intensity: Running at 110% vVO2max after high-load strength at 80-95% 1RM.
  • Part of a 50-90 minute daily team training session; HIIT block about 15 minutes including between-set recovery.
  • 1 session per week for the strength plus HIIT component.
  • In-season intervention across about 11-12 weeks.
  • Nonrandom two-team comparative training study
  • Yo-Yo IR2, VO2max and vVO2max, Match goals, and Match result were tracked.

Outcomes

Yo-Yo IR2

The strength plus HIIT group improved Yo-Yo IR2 distance, while the SSG comparator did not.

HIIT 902.5 +/- 147.5 to 1092.5 +/- 155.8 m, p=0.0002, d=1.25; post HIIT > SSG p<0.001.

Improved

VO2max

Estimated VO2max and vVO2max improved only in the strength plus HIIT group.

VO2max 57.6 +/- 2.0 to 60.2 +/- 2.1 mL/kg/min; vVO2max 17.4 +/- 0.5 to 18.1 +/- 0.5 km/h; post-group effects p<0.001.

Improved

Goals

The HIIT team scored more late-match goals during the intervention period.

Goals in last 30 minutes increased from 0.36 +/- 0.50 to 1.27 +/- 0.90, p=0.040, d=1.25.

Improved

Match result

The HIIT team's match results improved during the intervention period.

Wins increased from 5/11 before to 9/11 during intervention; league position improved from 7th to 3rd.

Improved

Insights

  • A weekly in-season session pairing high-load strength with short 15:15 intervals may improve high-intensity endurance in elite youth soccer.
  • Late-match scoring outcomes are promising but vulnerable to team, opponent, and tactical confounding.
  • Nonrandom team-level comparison should not be treated as proof that the protocol caused match results.

Limitations

  • Nonrandom comparison of two different teams.
  • No GPS or external-load data.
  • No strength or power tests due coach constraints.
  • Match outcomes may be affected by tactics, opponents, technical factors, and randomness.
  • Only elite under-19 male players.

Safety

  • Players missing more than 20% of training days because of injuries were excluded; the NXML sections reviewed did not report intervention adverse events.