• Measuring grip strength in older adults: comparing the grip-ball with the Jamar dynamometer

      Vermeulen, Joan; Neyens, Jacques C.L.; Spreeuwenberg, Marieke D.; van Rossum, Erik; Hewson, David; de Witte, Luc P. (Wolters Kluwer, 2015-12-31)
      Decreased grip strength is a predictor of adverse outcomes in older adults. A Grip-ball was developed that can be used for home-based self-monitoring of grip strength to detect decline at an early stage. The purpose of this study was to evaluate the reliability and validity of measurements obtained with the Grip-ball in older adults. Forty nursing home patients and 59 community-dwelling older adults 60 years or older were invited to participate in this study. Grip strength in both hands was measured 3 consecutive times during a single visit using the Grip-ball and the Jamar dynamometer. Test-retest reliability was described using intraclass correlation coefficients. Concurrent validity was evaluated by calculating Pearson correlations between the mean Grip-ball and Jamar dynamometer measurements and between the highest measurements out of 3 trials. Known-groups validity was studied using t tests. Eighty eight participants (33 men) with a mean age of 75 (SD = 6.8) years were included. Intraclass correlation coefficients for the Grip-ball were 0.97 and 0.96 for the left and right hands, respectively (P < .001), and those for the Jamar dynamometer were 0.97 and 0.98 for the left and right hands, respectively (P < .001). Pearson correlations between the mean scores of the Grip-ball and the Jamar dynamometer were 0.71 (P < .001) and 0.76 (P < .001) for the left and right hands, respectively. Pearson correlations between the highest scores out of 3 trials were 0.69 (P < .001) and 0.78 (P < .001) for the left and right hands, respectively. The t tests revealed that both the Grip-ball and the Jamar dynamometer detected grip strength differences between men and women but not between nursing home patients and community-dwelling older adults. Grip-ball measurements did not confirm higher grip strength of the dominant hand whereas the Jamar dynamometer did. The Grip-ball provides reliable grip strength estimates in older adults. Correlations found between the Grip-ball and Jamar dynamometer measurements suggest acceptable concurrent validity. The Grip-ball seems capable of detecting "larger" grip strength differences but might have difficulty detecting "smaller" differences that were detected by the Jamar dynamometer. The Grip-ball could be used in practice to enable home-based self-monitoring of grip strength in older adults. However, for implementation of the Grip-ball as a screening and monitoring device in practice, it is important to gain insight into intersession reliability during home-based use of the Grip-ball and clinical relevance of changes in grip strength. BACKGROUND AND PURPOSE METHODS RESULTS CONCLUSIONS
    • Stretching at the ankle joint: viscoelastic responses to holds and continuous passive motion

      McNair, Peter J.; Dombroski, Erik; Hewson, David; Stanley, Stephen N. (Wolters Kluwer, 2001-03-31)
      PURPOSE: To compare the effect of static holds and continuous passive motion on stiffness and force relaxation of the soft tissue structures resisting ankle joint dorsiflexion. METHODS: This study used a randomized repeated measures trial design. Twenty-four asymptomatic subjects (15 males and 8 females) with a mean age of 26 yr participated. A Kin-Com dynamometer was used to measure the stiffness and force relaxation response of tissues about the ankle joint in response to a plantar flexor stretch. A comparison was made of the response for a 1 x 60-s hold, 2 x 30-s holds, 4 x 15-s holds, and continuous passive motion for 60 s. All subjects undertook all conditions. The main outcome measures were 1) stiffness at the ankle joint as it moved to 80% of the maximum range of dorsiflexion, and 2) the decrease in force at 80% of the maximum range of motion of the ankle joint. RESULTS: Stiffness was decreased significantly (P < 0.05) for the continuous passive motion condition only. The mean magnitude of the decrease in stiffness was 16%. Across hold times, force decreased significantly (P < 0.05). Bonferonni contrasts indicated that there was a significant difference (P < 0.05) between the continuous passive motion condition and all other hold conditions. There were no significant differences (P > 0.05) between the 4 x 15-s, 2 x 30-s, and 1 x 60-s holds. The magnitude of the decline in force was 10.5%, 21.5%, 21.7%, and 19% for the 0-, 15-, 30-, and 60-s holds, respectively. The greatest decreases in tension were achieved in the first 20 s of a hold. CONCLUSION: If decreasing stiffness is a key aim of a stretching program, the findings indicate that continuous motion is more effective than holds. In contrast, if relaxation of peak tension is the main aim, then holds are most effective.
    • Variability of competitive performance of distance runners

      Hopkins, William G.; Hewson, David (Wolters Kluwer, 2001-09-30)
      PURPOSE: The typical variation in an athlete's performance from race to race sets a benchmark for assessing the utility of performance tests and the magnitude of factors affecting medal prospects. We report here the typical variation in competitive performance of endurance runners. METHODS: Repeated-measures analysis of log-transformed official race times provided the typical within-athlete variation in performance as coefficients of variation (CV). The types of race were cross-country runs (4 races over 9 wk), summer road runs (5 races over 4 wk), winter road runs (4 races over 9 wk), half marathons (3 races over 13 wk and 2 races over 22 wk), and marathons (2 races over 22 wk). RESULTS: Typical variation of times for the fastest quartile of male runners was 1.2-1.9% in the cross-country and road runs, 2.7% and 4.2% in half marathons, and 2.6% in marathons. Times for the slower half of runners in most events were more variable than those of the faster half (ratio of slower/faster CV, 1.0-2.3). Times of younger adult runners were more variable than times of older runners (ratio of younger/older CV, 1.1-1.8). Times of male runners were generally more variable than those of female runners (ratio of male/female CV, 0.9-1.7). CONCLUSION: Tests of endurance power suitable for assessing the smallest worthwhile changes in running performance for top runners need CV < or = 2.5% and < or = 1.5% for tests simulating half or full marathons and shorter running races, respectively. Most of the differences in variability of race times between types of race, ability groups, age groups, and sexes probably arise from differences in competitive experience and attitude toward competing.