Wayne L. Westcott
A few years ago, another researcher and I published the results of a study featuring beginning exercisers who performed strength training at either a faster repetition speed (7 seconds each) or a slower repetition speed (14 seconds each). We found that the subjects who performed their repetitions more slowly experienced significantly greater strength gains.1
We concluded that slower repetition speeds were preferable to faster repetition speeds for strength development, presumably due to less momentum and more muscle stimulus. While this may be true, it is possible that other factors influenced our findings. First let's examine the similarities and differences between the two training protocols.
Protocol similaritiesSimilarity No. 1.
Both exercise protocols required the same time under load for completion of the exercise set. Group 1 performed an average of 10 repetitions (ranging from eight to 12) in seven seconds each for a 70-second exercise set. Group 2 performed an average of five repetitions (ranging from four to six) in 14 seconds each for a 70-second exercise set. Similarity No. 2.
Both exercise protocols used a four-second eccentric muscle action on each repetition. Group 1 performed a two-second lifting (concentric) movement, paused one second in the position of full muscle contraction, and then performed a four-second lowering (eccentric) movement. Group 2 performed a 10-second lifting (concentric) movement followed by a four-second lowering (eccentric) movement.
Protocol differencesDifference No. 1.
The subjects in Group 1 spent less time in each concentric muscle action than Group 2. As noted above, Group 1 executed two-second lifting (concentric) movements, whereas Group 2 performed 10-second lifting (concentric) movements. Difference No. 2.
The subjects who performed 10-second lifting movements reported more training discomfort than the subjects who executed two-second lifting movements. In fact, only two of the 147 study subjects chose to train with 14-second repetitions after the study was completed, even though the slower repetition speed produced superior results.
It is notable that the Group 1 subjects spent approximately 30 percent of each repetition in concentric muscle action, whereas the Group 2 subjects, who attained greater strength gains, spent approximately 70 percent of each repetition in concentric muscle action. Based on this observation, I decided to take a closer look at the concentric action time versus the eccentric action time in repetitions of equal duration. Because beginning exercisers appear to be more comfortable with moderate-speed repetitions compared to slow-speed repetitions, I chose a six-second repetition speed for this study.
For this study, 54 women were randomly assigned to one of two training protocols. All of the subjects performed eight to 12 arm curls to the point of muscle fatigue on a Nautilus biceps curl machine equipped with a Fitness Advisor computer. The computer provided visual and audible guidance for each lifting (concentric) and lowering (eccentric) movement. Twenty-eight women performed six-second repetitions with a shorter concentric muscle action (two seconds lifting and four seconds lowering). They spent approximately 33 percent of each repetition in concentric muscle action. Twenty-six women performed six-second repetitions with a longer concentric muscle action (four seconds lifting and two seconds lowering). They spent approximately 66 percent of each repetition in concentric muscle action.
All of the subjects were assessed isometrically (via Microfit computer) for maximum biceps strength (90 degrees elbow flexion) before and after the 10-week training program. On average, the women who executed two-second concentric muscle actions increased their biceps strength by 9 pounds, and the women who executed four-second concentric muscle actions increased their biceps strength by 12 pounds (see Figure 1). Although data analyses fell slightly short of statistical significance (p<0.06), six-second repetitions performed with longer (four-second) concentric muscle actions compared favorably with six-second repetitions performed with shorter (two-second) concentric muscle actions, and may prove to be more effective for strength development over longer training periods.
While our preliminary research project requires replication studies, there appear to be advantages to spending a higher percentage of each repetition on the concentric muscle action. First, consider that muscles can produce more force output during eccentric actions than during concentric actions. That is, with a given weightload, the lifting movement is more difficult than the lowering movement. Second, consider that muscles can produce more force output during slower speeds than during faster speeds (see Figure 2). Consequently, it may make sense to use a slower speed during the more difficult lifting (concentric) action, and to use a faster speed during the easier lowering (eccentric) action.
Although our research has not shown six-second repetitions to be more effective than other controlled movement speeds, most people find this to be a comfortable repetition cadence.2
Of course, six-second repetitions have been widely used in fitness facilities since Arthur Jones recommended this exercise speed in 1970. Let me suggest that instead of always asking clients to perform six-second repetitions in a two seconds up and four seconds down format, you occasionally have them perform six-second repetitions in a four seconds up and two seconds down format. You may find, as did our study subjects, that this is a highly productive strength training protocol. Clients will still complete 10 repetitions in 60 seconds, but 40 seconds (rather than 20 seconds) will be used for the more challenging concentric muscle actions.
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Body Bar Systems Inc.
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Cybex International Inc.
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VR1 is the newest addition to the Cybex selectorized family, joining Eagle and VR3. This line offers a compact footprint plus an intuitive design for ease of use. With an eye toward contemporary design, the line features enclosed weight stacks that meet ASTM and EN safety standards. The line provides a host of options, allowing it to be customized.
efi Sports Medicine
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efi Sports Medicine's GTS machine makes Pilates accessible for every fitness level. GravityPilates employs the GTS's incline glideboard and cable pulley system, using body weight as resistance to produce a feeling of stretch and constant resistance throughout the entire motion of every exercise. GravityPilates instructors can adapt exercises by adjusting the level of the GTS incline.
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GP Industries Inc.
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New urethane dumbbells from GP Industries feature a solid design with a Uni-Lock handle, available in either a straight or tapered handle design. The urethane coating is designed for durability against wear. All weight increments are permanently engraved in white urethane and will not discolor or rub off. Weights range from 5 to 150 pounds in 5-pound increments. A half-size set — from 7.5 to 27.5 pounds — is also available.
Hampton Fitness Products Ltd.
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Hoist Fitness Systems
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Iron Grip Barbell Company
800 664-4766, www.irongrip.com
Made exclusively in the U.S., Iron Grip's urethane-encased solid steel dumbbells and fixed barbells feature a urethane coating that won't mar equipment, walls or floors, and heavy-duty welded construction. The welded construction and injection-molded exterior results in a dumbbell that is much shorter in length than pro-style dumbbells. This compact design makes urethane dumbbells easy and safe to handle. They also feature 12-sided, anti-roll heads with stable, flat, tip-resistant ends. Easy-to-read weight markings are permanently engraved and bonded into the surface.
Ivanko Barbell Company Inc.
800 247-9044; www.ivankobarbell.com
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Magnum Fitness Systems
800 372-0554; www.magnumfitness.com
The new 5000 Series of selectorized machines features large, round, bent tubing blended together into a low profile, with fully guarded pulleys and full rear shrouds. The 5000 Series has integrated Magnum's Biangular technology of multi-plane movement with optimally positioned weight stacks, and easy-to-reach and -use supplemental resistance and range-of-motion controls.
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Matrix Fitness Systems
866 693-4863; www.matrixfitness.com
Matrix provides its customers with a full line of selectorized strength equipment in an aesthetically appealing package. The strength equipment features oversized grips; towel and cup holders; ergonomic seating; extra-strong, round-form tubing; automotive-quality powdercoat finish; and color-coded adjustments that can be made from the exercise position.
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800 675-0171; www.nautilusone.com
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Paramount Fitness Corp.
800 721-2121; www.paramountfitness.com
Paramount designs and manufactures a full range of strength-training products. The 17-piece SP Circuit combines ergonomics, biomechanics and structural performance with contemporary aesthetics. Designed using parametric modeling, each unit fits a wide range of users comfortably, while extensive testing at or above maximum field applications assures long-term durability with minimal service requirements. All SP models meet or exceed ASTM and EN957 safety design standards for fitness equipment.
800 321-6975; www.power-systems.com
The Pro Power Pro Trainer Six-Station gym includes a cable crossover, two lat pulls, two low rows and a chin-up bar. The 11-gauge steel tubing frames have a baked-on, powdercoated finish, and the cable crossover has two fully assembled 200-pound weight stacks. Low rows have a 12-by-32-inch elevated seat, lat pulls have an adjustable knee roller pad, and both have 225-pound fully assembled weight stacks. Two 48-inch lat bars, two low row double handles, two single handles and two ankle straps are included. Custom embroidery is available, along with two frame and 25 upholstery colors.
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The Precor Icarian line of commercial strength equipment features more than 100 products in six categories, including machine-defined selectorized, user-defined selectorized, multi-stations, plateloaded, free weight equipment, and benches and racks. A redesigned selectorized line incorporates enhanced aesthetics and user-friendly features, with new elevated weight stacks and sleek shrouds. Precor Icarian Modular System components can be connected in virtually any configuration, with more than 100 pre-configured layouts of two- to 12-stack configurations. Precor Icarian equipment features 2-by-4-inch steel frames and high-quality pulleys and cables.
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Quantum Fitness Corp.
800 937-2282; www.quantumfitness.com
The patented Power Quad strength machine presents a closed kinetic way to isolate the quadriceps for fully functional rehabilitation of knee injuries, or to simply exercise the quadriceps. This is achieved by the pivot-seat design, which locks the hip angle for complete isolation, and is designed to offer greater muscle activation than with a leg extension. The Power Quad features a seat back adjustment to control knee flexion, non-encumbered walk-in design and extra large, non-slip foot plates.
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Star Trac offers user-focused strength equipment, including the HumanSport series, a line of six functional training strength machines. Each machine represents two traditional cable-motion pieces within one compact unit, facilitated by a dual-independent weight stack system. The versatile pieces feature distinctive styling, one-touch adjustment and swivel pulleys to ensure a smooth and unlimited range of motion. The space-saving HumanSport line offers users a diverse range of training options to explore new self-driven or personal trainer-led training techniques.
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Smart Circuits feature Strive's patented Smart Strength technology. The strength line is installed in commercial fitness centers, YMCAs, sports performance centers, rehab facilities and U.S. military fitness facilities, and used by celebrity trainers.
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PureStrength plateloaded equipment is designed to offer biomechanics that maximize muscle activation while respecting the safest trajectory for the joint. Ergonomic features include Pure Grip technology, a comfortable and natural grip design to fit all users. The Body Print System ensures the seat molds to the user's body shape for maximum support. Other features include Visual Flags and spring-loaded seat adjustments to help users find the right exercise position.
Troy Barbell &Fitness
800 872-7767; www.troybarbell.com
The new Troy solid-steel, urethane-encased dumbbell ends are press-fit and welded to a hard chrome, 32-millimeter straight handle that is finely knurled for a firm, comfortable grip. The head of each dumbbell is fully encased with polyurethane. The dumbbells are designed to maintain a 2 percent accuracy level.
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The IsoBar line of commercial weight bars uses patented sliding hand grips that are linked, thus remaining equidistant from the center of the bar for balance, symmetry and control. IsoBar combines the range of motion, isolation, variation and muscle recruitment afforded by dumbbells, with the control, simplicity and racking ability of barbells. Cable-attachment units also are available.
Vortex Fitness Equipment
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Vortex Fitness Equipment teamed up with HiTech Trainer and Dr. Brian Biagioli of the National Council on Strength and Fitness to produce a set of functional, sport, ADL and circuit training programs. The Vortex 30-Pack and HiTech Trainer offer pre-designed and customizable programs, meal and weight-loss programming, and the ability to track clients' results and scheduling online.
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