BIO-ARC Strength Leg Extension - Tuff Stuff (BA-707)

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BIO-ARC Strength Leg Extension - Tuff Stuff (BA-707) is available to buy in increments of 1

BIO-ARC Strength Leg Extension - Tuff Stuff (BA-707) -The BIO-ARC Strength Leg Extension Machine by TuffStuff isolates the quadriceps muscles of the leg and is ideal for developing the sought after “tear drop” above the knee. The BA-707 leg extension offers full range of motion throughout the entire exercise with greater muscle contraction incorporating more muscle fibers of the quad for better results. A self-adjusting roller pad and pop-pin adjustable back pad conforms perfectly to meet each individuals size and comfort level. And a 200 lb. selectorized weight stack provides plenty of resistance to “burn down” the quads. Choose from multiple powder coat and upholstery colors at no extra cost. 


TuffStuff is proud to introduce the Bio-Arc strength series, the first resistance machines to incorporate multiplanar movement of each machine’s seat, along a linear arc trajectory. The seat movement allows the user to move along the arc path in conjunction with the machine helping to maintain more optimal muscle length and improving the force of contraction and training stimulus. Three years in the making, from concepts and engineering to prototype, testing and refinements. Each of the Bio-Arc line's machines were tested, following initial design positioning, by an independent exercise consulting company. Pilot research studies combining joint positioning – using goniometry testing, along with muscle recruitment and activity measurements – through electromyographic (EMG) testing were performed to determine the optimal dimensions of each unit for final production. Every detail and design modifications were executed to exact specifications and re-tested. The end results, a patented Bio-Arc Technology that allows full body linear arc trajectory motion during execution of the exercise! 


EMG and goniometer testing were performed by an independent exercise research company. Four subjects (3 male and 1 female) were selected for the testing with height ranging from 5’ 1/4” to 6’ 1”. Subject selection was limited to individuals with sufficiently low subcutaneous adipose tissue to permit accurate electromyographic measurements. EMG activity was recorded for the primary and accessory muscle(s) that target the upper and lower body musculature; furthermore, contributions from accessory and antagonistic muscle groups were also evaluated. Measurements, testing, data collection and analysis by the independent researcher group on the Bio-Arc series, provided TuffStuff engineers with the necessary design modifications to optimize muscle recruitment of primary movers specific to each machine. 

Have questions about the new Patented BIO-ARC line of equipment by TuffStuff? Contact an IRON COMPANY® strength equipment specialist today at 1-888-758-7527 or email


  • Allows for full range of motion and greater muscle contraction during full extension outperforming traditional fixed position.
  • The user's entire body moves along a linear arc trajectory with the machine to optimize muscle recruitment.
  • Government Purchase: Available for open market Government and Military purchase through GSA contract GS-07F-0104M and CMAS contract 4-12-78-0066A

Additional BIO-ARC Strength Equipment Info Here:

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  • FRAME MATERIALS:  3" and 4-1/2” 11-gauge 120 wall round tubular steel with a combination of 2x4” 11-gauge 120 wall tubular steel. 
  • WELDS:  All welded construction by inert-gas MIG welding conforming with all Structural Welding Code-Steel Standards and Specifications.
  • PADDING:  Molded PU foam glued to 1” industrial plywood backing, combined with double-stitched premium upholstery.
  • CABLES:  3/16” USA-Made Certified EXERFLEX PRO® high performance fitness cable.
  • GUIDE RODS:  3/4” solid steel 1045 (tgp) highly polished hard chrome finish.
  • ADJUSTMENT PINS:  1/2" push-pull spring loaded solid steel adjustment pins with ultimate load of 9040 lbs. and 46042 sheer strength.
  • LINEAR SHAFTS:  1" precision Rockwell C60 grade solid shaft.
  • BEARINGS:  2" High precision linear sealed ball bearing (load rating of 1900 lbs.).
  • PULLEYS:  4-1/2", 3-1/2" and 2" fiberglass reinforced nylon pulley.
  • FASTENERS:  All frame bolts and nuts ard 3/8" and 1/2" zinc plated grade 8. Meets ANSI specifications.
  • CUSTOM STABILIZER FEET:  Heavy grade molded rubber base feet insures stability, prevents equipment movement, and may be bolted to the floor.
  • SELECTOR WEIGHT PINS:  Weight pins are solid steel, magnetic with ball-end to ensure a tight connection and secure fit.
  • WEIGHTS:  3/4" black painted solid steel plates with reduced noise and self-aligning low friction sleeves.
  • FINISH:  Choice of two primary colors: Gloss Charcoal Gray with Matte Black accent  or Platinum Sparkle with Matte Black accent. Custom colors available, please inquire with your sales representative.
  • UPHOLSTERY:  Premium Bolta Sport vinyl with PreFixx, formulated to resist bacteria, stains, mildew, oil and UV stabilized pigments. Meets most flammability test requirements. All upholsteries are double-stitched with “hidden” borders. Bolta Sport color swatches are available upon request. Sixteen standard colors. Custom colors are available – please inquire with your sales representative.
  • IMPORTANT NOTE: Equipped with 245 lbs. weight stack: weight lifted is the approximate combined user's weight and weight selected (see weight guide label).
  • Length x Width x Height: 64 x 50 x 58 in/163 x 127 x 147 cm
  • Weight:  550 lb/249 kg

Tuff Stuff Bio-Arc Strength upholstery color chart
Color samples as shown are close representations of the actual vinyl colors, and MUST NOT be used for an exact match of the color. Always request for the actual vinyl samples from IRON COMPANY

Tuff Stuff Bio-Arc Strength powder coat finish color options
Choice of two primary colors: Gloss Charcoal with Matte Black accent or Platinum Sparkle with Matte Black accent. Custom colors available, please inquire with your sales representative for additional cost and availability.


  • 10 YEARS: Frames, welds, linear shafts and weight plates.
  • 5 YEARS: Pivot bearings, pulleys, bushings, gas-shocks, and guide rods.
  • 3 YEARS: TrakHandles
  • 1 YEAR: Linear bearings and pull-pin components.
  • 6 MONTHS: Upholstery, cables, finish and rubber grips.
  • ALL OTHER PARTS  not mentioned, one year from the date of purchase to the original purchaser.

Shipping Included 

Freight cost included within the lower 48 states only. Ships via one of our various freight carriers on a wooden pallet. This delivery is considered to be a curbside delivery only and will be delivered to a location at your address that is acceptable for a tractor trailer at the drivers discretion. Customers are required to be available at the time of delivery to inspect the shipment and sign the delivery receipt. Your shipment includes a 24-hour notification call and lift gate service.