Accuracy of Seven Equations for Predicting 1-RM Performance of Apparently Healthy, Sedentary Older Adults

Abstract

This study compared the relative accuracy, similarity, and average error of 7 prediction equations (Brzycki) 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 (sqrt[Σ(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.

Effects of three different low-intensity exercise interventions on physical performance, muscle CSA and activities of daily living: A randomized controlled trial

“…Dynamic muscle strength was defined as the 1RM or the maximum amount of weight that a participant could lift throughout the complete range of motion (Wood et al, 2002). To calculate the % of 1RM, adjustable ankle cuff weights were used.…”

Determination of Shoulder Abduction Strength Using a Submaximal Elastic Band Test

“…Studies have estimated 1RM based on repetitions and intensity during submaximal testing in Paralympic rowers, 32 apparently healthy, sedentary older adults, 33 trained young adults, 34 and individuals with knee joint osteoarthritis. 35 However, repetitions completed at different intensities can differ on the basis of characteristics of the person being tested.…”

Validade das equações preditivas de uma repetição máxima varia de acordo com o exercício realizado em adultos jovens treinados

“…Neste sentido, os estudos que compararam equações preditivas nos exercícios leg press 45°1 7 , extensão de joelhos 17 10 . Vale destacar que a equação de Brzycki 8 já havia sido validada anteriormente em uma amostra semelhante 27 .…”

“…Alguns estudos têm investigado a validade das estimativas fornecidas por essas equações em populações distintas e com diferentes níveis de aptidão física [13][14][15] , com coeficientes de correlação elevados sendo encontrados entre a carga de 1-RM medida e aquela estimada por essas equações. Embora a validade de diversas equações preditivas de 1-RM, em diferentes exercícios de força, já tenha sido testada anteriormente em adultos sedentários 16,17 , em indivíduos treinados, algumas equações preditivas foram testadas e validadas para a estimativa de 1-RM apenas no exercício supino 18 . Considerando que as equações preditivas de 1-RM são ajustadas pela carga e pelo número de repetições realizadas em testes de força submáximos e que indivíduos treinados conseguem tolerar maior carga e repetições que indivíduos não treinados 19 , a nossa hipóte-se é que a validade dessas equações, quando aplicadas à indivíduos treinados em exercícios com pesos, seja diferente do observado previamente em indivíduos não treinados.…”