Journal of Orthopaedic & Sports Physical Therapy - Arthur Weltman, PhD

Measurement of Isokinetic Strength Prepubertal Males*

Mon, 15 Sep 2008 00:00:00 EST

Arthur Weltman, Carol Janney, Ken Strand, Clark Rians, Bernard R. Cahill, Frank I. Katch, Steven R. Tippett
* Supported in part by a grant from Hydra-Fitness Industries, Belton, TX.

Twenty-nine prepubertal males ( age = 8.2 ± 1.3 years) were evaluated for concentric isokinetic strength at the knee, shoulder, and elbow joints, [at the dominant (D) and nondominant (ND) sides]. At each joint, flexion (F) was compared with extension (E) at two speeds of 30°/sec (30) versus 90°/sec (90) over each 10% of the range of motion (ROM). Reliability was estimated between identical motions at the D versus ND side. Results for work at the knee joint indicated slightly higher work output at the ND side (23.5 versus 25.0 joules for D versus ND), significantly higher work output for extension compared to flexion (19.0 versus 29.2 joules for F versus E) and for the slower compared to the faster speed (26.2 versus 21.9 joules for 30 versus 90). At the shoulder joint, extension resulted in significantly greater work compared to flexion (14.2 versus 22.0 joules for F versus E) and the slower speed was associated with significantly greater work (1 9.7 versus 16.7 joules for 30 versus 90). At the elbow joint, the only significant difference observed for work occurred for speed, with the faster speed resulting in greater work (10.8 versus 9.5 joules for 30 versus 90). Analysis for torque scores at each of the three joints revealed that extension resulted in greater torque than flexion, 30°/sec resulted in greater torque than 90 O/sec and that peak torque scores occurred during the first 50% of ROM. Correlations to estimate reliability exceeded r = 0.70 for comparisons of torque and work scores for D versus ND. Age, height, and weight correlated r = 0.50 < r < 0.90 with peak torque during each of the motions. It was concluded that prepubertal males have similar patterns of concentric isokinetic strength measured at the knee, shoulder, and elbow joints compared to adults, because strength was greater during E versus F, for slower versus faster speeds, and during the initial phase of ROM.

J Ortho Sports Phys Ther 1988;9(10):345-351.

Specificity of Training on Computer Obtained Isokinetic Measures

Fri, 12 Sep 2008 00:00:00 EST

David H. Perrin, Arthur Weltman, Scott M. Lephart
The purpose of this study was to examine the effects of 7 weeks of isokinetic training on knee extension and flexion peak torque, torque acceleration energy, average power, and total work, and to observe the relationship between the increases in each of the isokinetic measures. Seventeen intercollegiate lacrosse players served as subjects and were assigned to an exercise or control group. Isokinetic training consisted of 3 sets of 25 repetitions at 270°/sec, 3 days per week for 7 weeks on an orthotron isokinetic dynamometer. All subjects were tested on a Cybex^® isokinetic dynamometer at speeds of 60, 180, and 270°/sec pre- and post-exercise or control condition. Results showed a significant training effect at 270°/sec for knee extension peak torque, torque acceleration energy, and average power, and knee flexion torque acceleration energy. High correlations were observed between the increases in peak torque, average power, and torque acceleration energy. These findings suggest that increases in average power, peak torque and instantaneous power may be expected as a result of isokinetic exercise training in healthy athletes.

J Orthop Sports Phys Ther 1989;10(12):495-498.

The Relationships among Isometric, Isotonic, and Isokinetic Concentric and Eccentric Quadriceps and Hamstring Force and Three Components of Athletic Performance

Wed, 10 Sep 2008 00:00:00 EST

Mark A. Anderson, Joe H. Gieck, David H. Perrin, Arthur Weltman, Richard A. Rutt, Craig R. Denegar
This study was supported in part by a grant from the Foundation for Physical Therapy, Inc.

The purpose of this study was to compare the relationships among isometric, isotonic, and isokinetic concentric and eccentric quadriceps and hamstring forces and three components of athletic performance in college-aged, male athletes. Bilateral quadriceps and hamstring muscle torque were obtained (N = 39) using a KinCom^® for concentric (rate at 60°/sec and 180°/sec), eccentric (rate at 30°/sec and 90°/sec), isotonic, and isometric (knee angles at 30° and 60°) contractions. Athletic performance was assessed using vertical jump performance, 40-yard dash time, and agility run time. The best predictor of 40-yard dash time was the right peak isokinetic concentric hamstring force at 60°/sec (R = .57; p < 0.05). The best predictor of agility run time was the left mean isokinetic eccentric hamstring force at 90°/sec (R = .58; p < 0.05). There were no significant correlations between any quadriceps or hamstring force and vertical jump. It was concluded that isokinetic eccentric quadriceps and hamstring forces were no better predictors of athletic performance than muscle forces assessed in other ways. However, they may be more predictive of some specific components of performance.

J Orthop Sports Phys Ther 1991;14(3):114-120.

Key Words: muscle strength, motor performance, knee

The Effects of Assistive Devices on the Oxygen Cost, Cardiovascular Stress, and Perception of Nonweight-Bearing Ambulation

Fri, 05 Sep 2008 00:00:00 EST

Cindy G. Holder, Esther M. Haskvitz, Arthur Weltman
Nonweight-bearing ambulation with the aid of an assistive device is often prescribed in the clinical setting. Little is known about the oxygen cost, cardiovascular stress, and perception of effort of these devices when applied to the same sample of subjects. Therefore, the present study compared the oxygen cost, cardiovascular stress [measured by heart rate (HR), blood pressure (BP) responses, and rate pressure product (RPP)], and perception of effort [measured by ratings of perceived exertion (RPE)] of unassisted ambulation (UA), nonweight-bearing ambulation using axillary crutches (AC), a standard walker (SW), and a wheeled walker (WW). Nine female subjects ambulated at self-selected velocities for 7 minutes during each ambulation mode. Oxygen consumption, HR, BP, and RPEs were obtained. As expected, UA resulted in the lowest VO₂ (11.2 ± 1.4 ml/kg·min^-1) and greatest velocity (1.24 ± 0.27 m/sec). Results also indicated that AC ambulation resulted in lower oxygen consumption per meter (0.4 ± 0.1 ml/kg·m^-1) and greater velocity (0.74 ± 0.18 m/sec) than either SW ambulation (0.6 ± .1 ml/kg·m^-1, 0.39 ± 0.09 m/sec) or WW ambulation (0.6 ± .1 ml/kg·m^-1, 0.40 ± 0.12 m/sec) (p < .05). No differences were observed among assisted ambulation modes for HR, BP responses, RPP, or RPE values. Because patients typically ambulate for a set distance (rather than a set time) and because the oxygen cost per unit distance was lowest for AC, it is suggested that, when possible, AC should be prescribed for nonweight-bearing ambulation.

J Orthop Sports Phys Ther 1993;18(4):537-542.

Key Words: gait, assistive devices, oxygen cost