Muscle power, the product of force × velocity, is a critical determinant of function in older adults. Resistance training (RT) at high speed has been shown to improve peak muscle power in this population; however, different functional tasks may benefit from the improvement of power at values other than "peak" values, for example, tasks that require a greater velocity component or a greater force component. This study compared the effect of high-speed RT on muscle performance (peak power [PP] and its components [PP force and PP velocity] and overall peak velocity [VEL]) across a broad range of external resistances. Thirty-eight older men and women were randomized to high-speed power training at 40% of the 1-repetition maximum (1RM) (n = 13 [74.1 ± 6.4 years]); traditional RT at 80% 1RM (n = 13 [70.1 ± 7.0 years]); or control (n = 12 [72.8 ± 4.1 years]). Measures of muscle performance were obtained at baseline and after the 12-week training intervention. Muscle power and 1RM strength improved similarly with both high-speed and traditional slow-speed RT. However, speed-related muscle performance characteristics, PP velocity and overall VEL, were most positively impacted by high-speed power training, especially at lower external resistances. Because gains in speed-related measures with high-speed training compared to traditional RT do not come at the expense of other muscle performance outcomes, we recommend using an RT protocol in older adults that emphasizes high-speed movements at low external resistances.

Objective. To examine the effect of high-speed power training (HSPT) on muscle performance, mobility-based function, and pain in older adults with knee osteoarthritis. Methods. Thirty-three participants (mean ؎ SD age 67.6 ؎ 6.8 years) were randomized to HSPT (n ‫؍‬ 12), slow-speed strength training (SSST; n ‫؍‬ 10), or control (CON; n ‫؍‬ 11) for a 12-week intervention. HSPT performed 3 sets of 12-14 repetitions at 40% of the 1-repetition maximum (1RM) "as fast as possible," SSST performed 3 sets of 8 -10 repetitions at 80% of the 1RM slowly, and CON performed stretching and warm-up exercises. Outcome measures included leg press (LP) 1RM and LP peak power (PP) from 40 -90% of the 1RM and the corresponding PP velocity (PPV) and PP force; 400-meter walk, Berg Balance Scale, and timed chair rise; and self-reported function and pain using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). Analysis of variance models were used to compare changes from baseline to 12 weeks. Statistical significance was accepted at P < 0.05. Results. LP PP improved in both HSPT and SSST compared to CON (P ‫؍‬ 0.04). LP PPV improved only in HSPT (P ‫؍‬ 0.01).There were also improvements in timed chair rise (P ‫؍‬ 0.002), WOMAC function (P ‫؍‬ 0.004), and WOMAC pain (P ‫؍‬ 0.02) across all of the groups. Conclusion. HSPT was effective at improving function and pain, but no more so than either SSST or CON. Because HSPT improved multiple muscle performance measures (strength, power, and speed), it is a more effective resistance training protocol than SSST and may increase safety in this population, especially when high-speed movements are required during daily tasks.

We examined whether high-speed power training (HSPT) improved muscle performance and braking speed using a driving simulator. 72 older adults (22 m, 50 f; age = 70.6 ± 7.3 yrs) were randomized to HSPT at 40% one-repetition maximum (1RM) (HSPT: n = 25; 3 sets of 12–14 repetitions), slow-speed strength training at 80%1RM (SSST: n = 25; 3 sets of 8–10 repetitions), or control (CON: n = 22; stretching) 3 times/week for 12 weeks. Leg press and knee extension peak power, peak power velocity, peak power force/torque, and braking speed were obtained at baseline and 12 weeks. HSPT increased peak power and peak power velocity across a range of external resistances (40–90% 1RM; P < 0.05) and improved braking speed (P < 0.05). Work was similar between groups, but perceived exertion was lower in HSPT (P < 0.05). Thus, the less strenuous HSPT exerted a broader training effect and improved braking speed compared to SSST.

Studies have shown that power training increases peak power in older adults. Evaluating the external resistance (% one repetition-maximum [1RM]) at which peak power is developed is critical given that changes in the components of peak power (force and velocity) are dependent on the %1RM at which peak power occurs. The purpose of this study was to compare the changes in peak power (and the external resistance at which peak power occurred) after 12 weeks of high-speed power training versus traditional slow-speed strength training. Seventy-two older men and women were randomized to high-speed power training at 40% of the one-repetition maximum (1RM) (HSPT: n=24 [70.8±6.8 yrs]); traditional RT at 80% 1RM (STR: n=22 [68.6±7.8 yrs]); or control (CON: n=18 [71.5±6.1 yrs]). Measures of muscle performance were obtained at baseline and after the 12-week training intervention. Changes in muscle power and 1RM strength improved similarly with both HSPT and SSST, but HSPT shifted the external resistance at which peak power was produced to a lower external resistance (from 67%1RM to 52%1RM) compared to SSST (from 65%1RM to 62%1RM)(p<0.05), thus increasing the velocity component of peak power (change: HSPT=0.18±0.21m/s; SSST=−0.03±0.15 m/s)(p<0.05). Because sufficient speed of the lower limb is necessary for functional tasks related to safety (crossing a busy intersection, fall prevention), HSPT should be implemented in older adults to improve power at lower external resistances, thus increasing the velocity component of power and making older adults safer in their environment. These data provide clinicians with the necessary information to tailor exercise programs to the individual needs of the older adult, affecting the components of power.

Objective. Frontal plane knee malalignment may increase progression of knee osteoarthritis (OA) and hasten functional decline. An accurate nonradiographic measure of knee alignment is necessary because the gold standard measure, the long-leg radiograph, is costly and often unavailable. Moreover, nonradiographic measures of knee alignment have not been validated in an obese population, where knee OA is common. The purpose of this study was to develop and assess the concurrent validity and reliability of a nonradiographic measure of frontal plane knee alignment and demonstrate the accuracy of the measure in an obese population. Methods. Fifty-five subjects (41 women, 14 men; mean ؎ SD age 62.9 ؎ 10.3 years) with knee OA were examined. A nonradiographic measure (umbilical method) of frontal plane alignment, using the landmarks of the umbilicus, knee, and ankle, was compared with the radiograph gold standard. Statistical significance was accepted at P < 0.05. Results. Eighty-nine percent of the participants had a body mass index (BMI) placing them in the overweight or obese category (mean ؎ SD BMI for all subjects 31.3 ؎ 6.1 kg/m 2 ). Radiographic measures of alignment ranged from 9.1°valgus to 14.3°varus (76% of the participants had varus alignment, 12% had valgus alignment, and 2% had neutral alignment). Umbilical measures ranged from 1°valgus to 21°varus. The umbilical measure was significantly correlated with the radiographic method (r ‫؍‬ 0.75, P < 0.001). The error of the umbilical measure was not significantly correlated with the BMI (r ‫؍‬ ؊0.21, P ‫؍‬ 0.13). Conclusion. The umbilical method of assessing frontal plane knee alignment is a valid surrogate for the radiographic gold standard and retains its accuracy in an obese population.