Among many other factors, fall risk in older adults has been associated with muscular weakness and decreased speed o f movement. It has been speculated that the ability to recover from a trip or a stumble may be affected by speed of stepping and muscular power. In order to assess the effects of muscular power improvement on stepping speed, 48 older adult males and females (65-82 yrs) were randomized into either (1) a high-velocity resistance training (HVRT) program that was designed to improve strength and power of all major muscle groups of the lower extremity, or (2) a flexibility and upper body strength training (FUBT) program that was designed to be a beneficial exercise program without affecting strength and power of the lower extremity. Subjects exercised three days per week for 12 weeks. Before and after the exercise programs, stepping speed, strength and power tests were administered, in that order. The stepping tests included laboratory stepping tests (an involuntary stepping test:​ a Lateral Destabilization (LD) which utilized a lateral weight-dropping hip pull test;​ a Lateral Stepping (LS) test and a Step Up (SU) test:​ voluntary step tests in response to light stimuli), and clinical stepping tests using a stop watch and minimal props (Side Stepping (SS), Repeated Step Up (RSU), Four Square Step Test (FSST) and Step in Place test (SIP)). If the clinical stepping tests relate well with the laboratory stepping tests, clinicians may have reasonable options for assessing rapid stepping speed in older adults without the required technical set-up of the laboratory stepping tests. Strength and power tests were performed for Leg Press (LP), Calf Raise (CR), Hip Abduction (ABD), Hip Adduction (ADD) and Hip Flexion (HF) in the fitness center where the exercise training occurred.

As a result of exercise training, the HVRT group significantly improved all strength and power measures, however, the FUBT group also improved on LP and CR power. The power improvement of the FUBT group may be due to low performance prior to the exercise program, and increased activity outside of the exercise program as a result of improved well-being. Both groups significantly improved on many parameters of stepping test performance. Improvements in stepping speed parameters (reaction time (RT), weight shift time (WST), magnitude of anticipatory postural adjustment (APA) and stepping speed (SPD)) were predicted by pre-intervention performance on the stepping parameter being tested, status (strategy used during the LD test:​ normal stepping or shuffle (multiple) stepping), changes in strength, changes in power, exercise group assignment, sex, attendance and age. The addition of power variables to the regression models predicting the change in WST, APA and SPD following exercise improved the explanatory ability of the models by 11.4%, 9.1%, and 9.3%, respectively, with the largest improvement noted for LD SPD (15.5%). The addition of power variables to regression models predicting the change in clinical stepping test time explained an additional 34.4%, 10.5% and 8.6% of the variance in performance changes following exercise for the RSU, SIP and SS tests, respectively, but little explanatory ability for the FSST. Further, the addition of laboratory stepping parameters to the regression models explaining the variance in the improvement in SIP clinical stepping test performance following exercise explained an additional 28.7% of the variance, but had little affect on the other clinical tests.

As a result of this study, it can be concluded that improving lower extremity strength and power is a valid method o f improving rapid stepping performance in older adults. Further, lower extremity power contributed individually to stepping performance parameters (WST, APA and SPD), explaining up to 15.5% and 34.4% more of the variance in laboratory and clinical stepping improvements, respectively, following exercise training than the other predictive factors - including strength. The clinical stepping tests also improved following exercise training, but only RSU, SIP and SS were markedly affected by changes in power above and beyond the other predictive factors. SIP was the only clinical test that was markedly related to the laboratory stepping tests, which explained an additional 28.7% of the variance in SIP improvement following exercise training, making it the best candidate for a simple measure of stepping speed in older adults. Since strength training has proved to be an effective remedial measure for fall prevention, and since muscular power contributes to stepping speed changes above and beyond that of strength, adding a high-velocity component to strength training programs allows the added benefit of improving stepping speed in older adults, while not limiting strength improvements. This may prove to be a beneficial step forward in the construction of beneficial fall prevention programs for older adults.