Resisted sled sprinting improves acceleration by enhancing horizontal force application and force production.
But the key challenge is how to load the sled properly—too light or too heavy makes training less effective or non-specific.

Methods of Choosing Sled Load

Method

What It Is

Pros

Cons

Absolute Load (kg)

Fixed weight on sled (e.g., 10 kg)

Simple

Doesn’t account for athlete size or strength — inconsistent stimulus

% of Body Mass (%BM)

Load based on body weight (e.g., 20% of body mass)

Easy to calculate, scales with size

Doesn’t consider individual sprint ability; different athletes get very different effects

% Velocity Decrement (%Vdec)

Load that causes a certain drop in unresisted sprint velocity (e.g., sprint is 10% slower)

Individualized; accounts for sprint performance; works on any surface

Needs timing gates; no defined “max” load, so hard to periodize

% Maximal Resisted Sled Load (%MRSL)

Load where athlete can just maintain acceleration between 10–20 m

Individualized, measurable “max,” allows for periodization, correlates with performance

Requires multiple timed trials; a bit more testing time

How to Find the Load

For %Vdec method

  1. Pick your training distance (e.g. 20 m).
  2. Measure unresisted sprint time/velocity.
  3. Test several sled loads over the same distance.
  4. Choose the load that reduces your velocity by the desired percentage (commonly 10–25% for acceleration work).

For %MRSL method

  1. Sprint 0–20 m with different loads.
  2. Measure velocity in 10–15 m and 15–20 m splits.
  3. If 15–20 m is faster → still accelerating → increase load.
    If 15–20 m is slower → decelerating → load is above MRSL.
  4. The heaviest load where you’re still accelerating is your MRSL.
  5. Train at a percentage of MRSL (e.g. 50–80% MRSL) depending on your focus.

Practical Notes

  • Heavier loads increase trunk lean → more specific to early acceleration mechanics.
  • MRSL values typically range from 30–65% of body mass for males, 22–50% for females.
  • Light loads (<20% Vdec) = more speed-oriented.
  • Heavy loads (40–60% Vdec or near MRSL) = more force and horizontal application development.

In Short

  • Don’t use fixed weights or % body mass — they’re too generic.
  • Use % velocity decrement for simplicity or %MRSL for precise, periodized training.
  • Choose distances (10–20 m) that match your acceleration phase, since that’s what sled's best target.

Perfect — let’s dig deeper into how different % velocity decrements (%Vdec) affect training outcomes and how to choose the right one depending on your goal or training phase.

This is one of the most practical and widely used ways to prescribe sled load because it directly relates the resistance to your own sprinting ability.

 What %Vdec Means

%Vdec = how much slower you run with the sled compared to your normal (unresisted) sprint.

Example:

  • Your 20 m unresisted sprint velocity = 8.0 m/s
  • With a sled, velocity = 7.2 m/s
  • Decrement = (8.0 – 7.2) / 8.0 = 10% Vdec

 Training Effects by Load Zone

%Vdec Range

Load Type

Typical % of Body Mass (approx.)

Primary Adaptation

Best For

0–10% Vdec

Light load

~5–15% BM

Improves max velocity & technique, minimal interference

Speed endurance, upright mechanics

10–20% Vdec

Moderate load

~15–25% BM

Enhances acceleration and force application in early steps

Early acceleration, transitional work

20–30% Vdec

Heavy load

~25–40% BM

Trains horizontal force production, trunk lean, and drive phase

Force emphasis, special prep

30–50% Vdec

Very heavy load

~40–65% BM

Builds horizontal strength and neural drive; strong trunk and hip extension

Early GPP, strength-acceleration work

>50% Vdec

Maximal load

>65% BM

Nearly “marching” pace; develops pure force capacity, not speed

Off-season or specific strength phase

(BM = body mass, these are rough conversions — surface friction and sled type change the exact %.)

How to Interpret It

  • Lower %Vdec (≤15%) → movement looks and feels like sprinting; mechanics stay close to unresisted running.
    Higher %Vdec (≥30%) → movement becomes more “push-dominant”; slower, but builds horizontal power.
  • The sweet spot for most acceleration development: 20–30% Vdec.
  • Loads beyond 40% Vdec can be great for short (5–15 m) resisted efforts focusing on horizontal force and trunk angle.

How to Apply It by Training Phase (Indoor season)

Training Phase

Goal

Recommended %Vdec

Example Distance

General Prep (Aug–Sep)

Force development, early acceleration strength

30–50% Vdec

10–20 m

Transition (Oct)

Blend of force and speed

20–30% Vdec

15–25 m

Special Prep (Nov–Dec)

Specific acceleration power

15–25% Vdec

20–30 m

Pre-Comp / Comp (Jan–Feb)

Maintain speed and sharpness

5–15% Vdec

30 m+

Practical Example

Let’s say your 20 m unresisted sprint time is 3.00 s.

To train at different %Vdec:

  • 10% Vdec: target 3.33 s (light load, near top speed)
  • 20% Vdec: target 3.60 s (medium load, power)
  • 30% Vdec: target 3.90 s (heavy load, force)
  • 50% Vdec: target 4.50 s (very heavy, strength)

 Key Takeaways

  • %Vdec gives you an individualized, evidence-based way to pick sled load.
  • For most sprinters:
  • 15–25% Vdec = best overall balance for acceleration.
  • 30–50% Vdec = great in early prep for building force.
  • 5–15% Vdec = ideal for comp-season speed maintenance.
  • Keep distance short (10–30 m) and ensure mechanics remain sprint-like even at heavier loads.