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Abstract This study compared the relative accuracy, similarity, and average error of 7 prediction equations (Brzycki, 1993; Epley, 1985; Lander, 1985; Lombardi, 1989; Mayhew, Ball, Arnold, O'Connor, Simmons, Wathen, 1994) for estimating 1-repetition maximum (1-RM) performance of older sedentary adults using Hammer Strength Iso-Lateral resistance exercise machines. Data were collected from 49 apparently healthy volunteers (26 males, 23 females) aged 53.55 ±3.34 (mean ± SD) years. 1-RM scores were obtained for biceps curl, chest press, high latissimus dorsi (lat) pull, incline chest press, leg curl, leg extension, low lat pull, leg press, shoulder press, and triceps extension. Repetitions to fatigue (RTF) for each exercise were determined by assigning each subject a percentage of his or her 1-RM ranging from 50% to 90%. Subjects performed as many repetitions as possible with the predetermined resistance. Predicted 1-RM (1-RMP) was evaluated by relative accuracy (correlation between 1-RM and 1-RMP), similarity (paired t-test between 1-RM and 1-RMP), and average error (sqrtS(1RMP - 1RM)2/(n - 1)). Relative accuracy, similarity, and average error improved significantly and gender differences were minimal when RTF £ 10. Accuracy of prediction equations varied over different resistance exercises. The Mayhew, Ball, Arnold et al. (1992), Epley (1985), and Wathen (1994) formulas evidenced the lowest average error (AE) and highest relative accuracy over the resistance exercises examined; however, both absolute AE and AE expressed as a percent of mean 1-RM were quite high for all formulas over all exercises.
Wood et al. (Sat,) studied this question.