Effects of changing from full range of motion to partial range of motion on squat kinetics.

Abstract
It is commonplace for people involved in recreational weight training to limit squat depth to lift heavier loads. This study compares differences in movement kinetics when squatting in the full range of motion (FROM) vs. partial range of motion (PROM). Ten men with a 1-year minimum of resistance training attended 4 sessions each comprising 4 sets of squats following one of FROM for 10 repetitions (FROM10) at an intensity of 67% 1 repetition maximum (1RM) FROM squat, PROM for 10 repetitions (PROM10) at 67% 1RM PROM squat, FROM for 5 repetitions (FROM5) at 83% FROM squat or PROM for 5 repetitions (PROM5) at 83% 1RM PROM squat. Movement velocity was not specified. Squat kinetics data were collected using an optical encoder. Differences between conditions were analyzed by repeated-measures analysis of variance and expressed as mean differences and standardized (Cohen) effect sizes with 95% confidence limits. The PROM5 power was substantially more than the PROM10 (98 W, -21 to 217; mean, lower and upper 95% confidence limits), FROM5 (168 W, 47-289), and FROM10 (255 W, 145-365). The force produced during PROM5 was substantially more than PROM10 (372 N, 254-490), FROM5 (854 N, 731-977), and FROM10 (1,069 N, 911-1227). The peak velocity produced during FROM10 was substantially more than FROM5 (0.105 m·s(-1), 0.044-0.166), PROM10 (0.246 m·s(-1), 0.167-0.325), and PROM5 (0.305 m·s(-1), 0.228-0.382). The FROM5 was substantially more than FROM10 (86 J, 59-113), PROM5 (142 J, 90-194), and PROM10 (211 J, 165-257). Therefore, either range of motion can have practical implications in designing resistance training programs depending on if the training goal is related to power and force development, maximizing work output or speed. Moderate-load PROM training, common among recreational weight trainers, is unlikely to provide higher movement kinetics.

PMID: 22222322
From FT

Peak Power

The participants produced higher mean concentric peak power during PROM5 (1,051 ± 165 W) than FROM10 (796 ± 151 W), PROM10 (953 ± 221 W), or FROM5 (883 ± 209 W). Peak power produced during PROM5 was substantially more than the PROM10 (98 W, -21 to 217, mean, lower and upper 95% confidence limits), FROM5 (168 W, 47–28), and FROM10 (255 W, 145–365) (Figure 1). The FROM5 also generated “moderately” more power than FROM10 (87 W, 21–153, d = 0.57).

Peak Force

The participants produced more mean concentric peak force of during PROM5 (2,192 ± 366 N) than FROM10 (1,123 ± 195 N), PROM10 (1,820 ± 404 N), or FROM5 (1,338 ± 250 N). The force produced during PROM5 was substantially more than PROM10 (372 N, 254–490), FROM5 (854 N, 731–977), and FROM10 (1,069 N, 911–1,227)

Peak Velocity

The participants produced higher peak velocity during FROM10 (0.83 ± 0.13 m·s-1) than PROM10 (0.58 ± 0.06 m·s-1), FROM5 (0.72 ± 0.13 m·s-1), or PROM5 (0.52 ± 0.08 m·s-1). The peak velocity produced during FROM10 was substantially more than FROM5 (0.105 m·s-1, 0.044–0.166), PROM10 (0.246 m·s-1, 0.167–0.325), and PROM5 (0.305 m·s-1, 0.228–0.382)

Concentric Work

The participants produced more mean concentric work during FROM5 (582 ± 67 J) than FROM10 (496 ± 57 J), PROM10 (372 ± 74 J), or PROM5 (441 ± 78 J). The total concentric work produced during FROM5 was substantially more than FROM10 (86 J, 59–113), PROM5 (142 J, 90–194), and PROM10 (211 J, 165–257) (Figure 4). Also of interest, FROM10 generated a “large” amount more total work per repetition than PROM10 (125 J, 84–166, d = 2.18).

Squat Depth

The mean squat depth was only relevant when comparing different intensities in the same intended range of motion. The participants were able to squat deeper during the FROM10 condition (58.0 ± 6.1 cm) than the FROM5 (53.8 ± 9.5 cm) by a “moderate” 4.2-cm difference (0.4–8.0, d = 0.70). The difference between PROM10 (25.6 ± 3.9 cm) and PROM5 (25.0 ± 3.9 cm) was a “trivial” 0.60 cm (-2.0 to 3.2, d = 0.13).
training with heavy PROM squats elicited the greatest force and power, whereas training with heavy FROM squats produced the greatest work per repetition. We observed that training with moderately loaded FROM squats produced the highest peak velocity. Finally, training with moderately loaded PROM squats did not excel in any kinetic variable studied here. As a result, we recommend that a variety of squat depths and loads should be prescribed depending on the individual athlete's muscle characteristics and training goals.
The participants involved in resistance training should consider the use of near-maximal PROM squats if their goal is to exert maximal force or power through a limited range of motion. Because resistance training programs designed to change body composition (e.g., hypertrophy, fat loss) are reliant not so much on power and force but more on total work performed, high-intensity FROM squats should be the focus. Because half as many repetitions are as the FROM10 condition, twice as many sets will be needed to ensure a sufficient total work is performed. Because the highest velocity was achieved in the FROM10 condition, athlete seeking goals dependent on high velocity, such as running and jumping, should employ predominantly lighter, FROM squats. The set design that seemed to have no discernable advantages was PROM10 because it did not maximize work, velocity, force, or power. Unfortunately, most recreationally training individuals are aware of the necessity for high volume training for hypertrophy from bodybuilding magazines (34) and thus target the 8–12 repetition range with a moderate load (30). Recreational athletes also tend to have low skill in performing full depth squats and pay little conscious attention to movement velocity. Partial repetition squats performed in the moderate to high repetition range seems to have the least benefit.