Resisted vs. Unresisted Sprint Training: What Works Best?

Sprinting is crucial in rugby, impacting speed, acceleration, and momentum in contact situations.

Resisted Sprint Training (RST) and Unresisted Sprint Training (UST) are both used in speed development.

But which is more effective?

This study compared UST vs. RST (50% body mass) in youth rugby players over a 4-week period.

Is unresisted or heavy sled resisted sprint training best for improving sprint performance and lower body strength?

Study: A Randomized Controlled Trial of Unresisted vs. Heavy Resisted Sprint Training Programs: Effects on Strength, Jump, Unresisted and Resisted Sprint Performance in Youth Rugby Union Players​

What did the researchers do?

Researchers had 35 U-19 male academy rugby players perform Unresisted Sprint Training (UST) or Resisted Sprint Training (RST; 50% BM)

Training Protocol

• 4-week program, 3x per week.
• Sled-resisted sprints (RST) vs. unresisted sprints (UST).
• Strength exercises were minimized to isolate the sprint training effects.

Measured Variables

• Sprint Performance: 10m, 30m, max velocity (Vmax)
• Strength-Power: Squat 1RM, Isometric Squat Test (ISqT), Nordic Hamstring Strength (NHE), Vertical and Horizontal Jump

What were the results?

Sprint Performance

• UST → Improved unresisted 30m sprint time.
• RST → No improvement in unresisted sprint performance.
• Both groups significantly improved resisted sprint performance (10m, 30m, Vmax).

Strength-Power

RST Group saw significant gains in:

• Isometric squat peak force (ISqT)
• Horizontal jump distance
• Nordic Hamstring Strength (NHE)

Neither group improved Squat 1RM or CMJ and there were no major differences between UST and RST for overall strength or jump performance.

What does this mean?

• Both methods improve resisted sprint performance.
• UST is superior for improving unresisted sprint speed.
• RST enhances isometric and eccentric strength but does not improve unresisted sprint speed.
• UST and RST can be viable alternatives when weight room training is reduced during competition.

Limitations

• Only 4 weeks—longer training durations may reveal different trends.
• Fixed resistance load (50% BM)—not individualized for players’ strength levels.
• Minimal strength training—not reflective of typical in-season rugby training.

Coach's Takeaway

• Use UST if the goal is max velocity and acceleration in an unresisted sprint.
• Use RST if the goal is to maintain strength when weight room sessions are limited.
• Both methods work for resisted sprint performance—choose based on specific team needs.