The BUILT Strength Infinite Series Back Extension is a commercial-grade selectorized machine built to load the posterior chain directly and repeatedly — spinal erectors, glutes, and hamstrings working through a controlled extension arc with smooth, consistent resistance from a 200 lb weight stack. Pin-select adjustments keep load changes fast between sets, supporting everything from warm-up volume to heavy working sets.

Adjustable hip pads and handlebars let every user dial in the correct starting position — proper hip height and grip placement locked in before the first rep, keeping spinal alignment safe and the movement pattern repeatable across an entire session.

Primary muscles targeted

Erector Spinae Glutes Hamstrings

Secondary muscles

Adductors Core

Key features

200 lb Selectorized Weight Stack

Pin-select resistance up to 200 lb — a heavier ceiling than the standard model, supporting advanced athletes running high-load posterior chain programming.

Adjustable Hip Pads & Handlebars

Both the hip pad height and handlebar position adjust independently — locking every user into correct spinal alignment regardless of torso length or build.

Smooth, Controlled Motion

The resistance path follows a natural extension arc with consistent tension throughout — clean mechanical loading on the posterior chain from bottom stretch to full extension.

Barbell Resistance Option

Users can hold a barbell across the upper back to add resistance beyond the weight stack — extending the loading range for advanced athletes who have outpaced selectorized limits.

Heavy-Duty Commercial Frame

Built for high-frequency commercial use — handles daily high-load training in professional facilities and serious home gym setups without compromise.

Specifications

Dimensions (L × W × H)

48" × 39" × 62"

1219 × 991 × 1575 mm

Machine Weight

597 lb

271 kg

Weight Stack

200 lb

91 kg · Pin-select selectorized

Condition

New

Commercial performance standard

Adjustability

Hip Pads & Handlebars

Independent adjustment for correct alignment across all body sizes

Price

Collections

Back Selectorized Machines