Jessica Biel Reveals Intense ‘Matchbox’ Movie Training Regimen Designed Around Back Injury

LOS ANGELES — Jessica Biel has pulled back the curtain on the grueling physical preparation for her upcoming role in the Mattel Films action thriller “Matchbox,” sharing a training montage that underscores a growing trend in Hollywood: elite actors adopting functional, injury-conscious strength protocols over purely aesthetic routines.

The footage, posted to Biel’s social channels this week with commentary from longtime trainer Ben Bruno, reveals a program built heavily on unilateral leg work, core stabilization under load, and modified squat patterns — all engineered after Biel aggravated a lower-back issue months before filming began. Bruno, whose client roster has included Chelsea Handler and Kate Upton, emphasized that the actress’s regimen prioritizes lower-body volume over upper-body isolation, contrary to assumptions driven by a viral back-and-arm clip she posted in December.

“People understandably want to know about her back workout — the thing is, Jess does full-body workouts and actually focuses a bit more on legs and butt than upper body,” Bruno says in the video. The disclosure reframes the conversation around celebrity fitness, shifting focus from “spot training” to systemic resilience.

The “Matchbox” production, based on the die-cast toy line and directed by Sam Hargrave for Paramount and Mattel Films, marks Biel’s most physically demanding role since the NBC thriller “The Sinner” and the USA Network series “Cruel Summer.” While plot details remain under wraps, the casting of Biel — alongside John Cena and Sam Richardson — suggests a high-octane ensemble piece in the vein of the “Fast & Furious” franchise, which Hargrave’s second-unit work helped define.

Bruno’s programming for Biel leans on several advanced methodologies gaining traction in performance coaching:

**Wall-supported squat variations** using a foam roller against the spine allow heavy loading of the quads, glutes, and hamstrings while offloading lumbar compression. The progression from goblet to double-dumbbell to Bulgarian split-squat versions demonstrates a deliberate overload strategy that spares the lower back — a critical adjustment given Biel’s injury history.

**Horizontal ring rows with a forward slide** integrate posterior-chain strength (rhomboids, traps, rear delts, lats) with dynamic core control. The isometric hold at the top of each rep, with shoulders actively retracted, builds scapular stability that carries over to pushing and pressing durability.

**Resisted lateral-plane work** — banded lateral lunges and side-plank knee drives — forces the trunk to resist rotational and translational forces simultaneously. This mirrors the multi-directional demands of stunt choreography, where actors must absorb impact while maintaining orientation.

**Isometric split-squat holds with lateral raises** combine unilateral leg endurance, shoulder stability, and anti-rotation core demand in a single movement. The mechanical disadvantage of raising a dumbbell laterally while pinned in a deep lunge magnifies the trunk’s stabilizing role.

**Low-side plank with overhead reach and top-leg lift** targets the lateral chain — obliques, gluteus medius, quadratus lumborum — while challenging shoulder girdle integrity. The flexed ankle cue on the raised leg ensures glute engagement rather than hip-flexor dominance.

A notable accessory drill, the side-lying press-and-reach, serves as a low-load shoulder-health primer. Biel’s husband, Justin Timberlake, anchors her legs in the clip; in gym settings, a glute-ham developer achieves the same fixation.

The routine reflects a broader industry shift. Where 2000s-era action stars often chased hypertrophy through body-part splits, today’s performers — think Alison Brie in “GLOW,” Florence Pugh in “Thunderbolts,” or Glen Powell in “Twisters” — favor movement-pattern training that bulletproofs joints for wire work, fight choreography, and long days on concrete sets. Bruno’s use of isometrics, tempo control, and external resistance (bands, dumbbells, rings) aligns with protocols used by NFL combine prep facilities and Olympic development programs.

For general-population trainees, the takeaway isn’t replication but adaptation. The wall-supported squat pattern is accessible to anyone with a foam roller and a pair of dumbbells; ring rows scale via body angle; band-resisted lateral work requires $20 of equipment. The core principle — train around pain, not through it — applies universally.

Biel’s “Matchbox” training block wraps as the film moves into post-production for a 2026 theatrical release. The first official trailer is expected to drop at San Diego Comic-Con in July.