A Predictive Equation Using Seated Medicine Ball Throw As A Measure Of Upper-limb Power In Older Men

Maximal strength (1RM) and peak power (PP) are critical markers of physical function and independence in older adults. Recently, a predictive equation using the Seated Medicine Ball Throw (SMBT) to determine upper-limb power was validated in a sample of older women using a chest-press pneumatic resistance training machine. To our knowledge, a similar equation has not been developed for older men with and without Parkinson’s disease (PD). PURPOSE: To develop equations to determine 1RM and PP values produced by the SMBT with a 3-kg medicine ball. METHODS: Seventeen older men (69.9 ± 5.9 y), 9 with PD and 8 without, completed 1RM and PP testing on the Keiser pneumatic chest press machine (Keiser Corp., Fresno, CA). Stepwise multiple regression analyses produced models that included PD diagnosis, age, and SMBT distance for predicting 1RM and PP from the SMBT. RESULTS: Both age and PD diagnosis were excluded from both predictive models due to their lack of significance. For the computation of 1RM the model was: 1RM = 17.582 + 8.884 [SMBT (m)] (r = .509, SEE = 10.2 kg, p = .037). The predictive equation for PP was: PP = 146.829 + 130.768 [SMBT (m)] (r = .586, SEE = 122.236 W, p = .013). Using a subgroup of 70%, we determined that correlations between predicted and actual values were similar to the original sample (1RM: r = .589; PP: r = .640). Coefficients of determination were .74 for 1RM and .66 for PP. Mean absolute errors and mean absolute percentage errors for 1RM were 7.5 kg and 14.4%, respectively, and for PP were 95.2 W and 14.5%. CONCLUSIONS: These models may allow clinicians and researchers to use the SMBT as an indirect measure of 1RM and PP in older men with and without PD reducing the need for more expensive assessment equipment and extended testing protocols. It is suggested that these analyses be repeated using a larger sample, and that a second model be produced to predict 1RM and PP in women.