Calculation of Force and Power during Bench Throws Using a Smith Machine: The Importance of Considering the Effect of Counterweights

Abstract

For achieving accurate and safe measurements of the force and power exerted on a load during resistance exercise, the Smith machine has been used instead of free weights. However, because some Smith machines possess counterweights, the equation for the calculation of force and power in this system should be different from the one used for free weights. The purpose of this investigation was to calculate force and power using an equation derived from a dynamic equation for a Smith machine with counterweights and to determine the differences in force and power calculated using 2 different equations. One equation was established ignoring the effect of the counterweights (Method 1). The other equation was derived from a dynamic equation for a barbell and counterweight system (Method 2). 9 female collegiate judo athletes performed bench throws using a Smith machine with a counterweight at 6 different loading conditions. Barbell displacement was recorded using a linear position transducer. The force and power were subsequently calculated by Methods 1 and 2. The results showed that the mean and peak power and force in Method 1 were significantly lower relative to those of Method 2 under all loading conditions. These results indicate that the mean and peak power and force during bench throwing using a Smith machine with counterweights would be underestimated when the calculations used to determine these parameters do not account for the effect of counterweights.

Key words

upper body - weight training - linear position transducer

• References

• 1 Alemany JA, Pandorf CE, Montain SJ, Castellani JW, Tuckow AP, Nindl BC. Reliability assessment of ballistic jump squats and bench throws. J Strength Cond Res 2005; 19: 33-38
• 2 Argus CK, Gill N, Keogh J, Hopkins WG, Beaven CM. Effects of a short-term pre-season training programme on the body composition and anaerobic performance of professional rugby union players. J Sports Sci 2010; 28: 679-686
• 3 Bevan HR, Owen NJ, Cunningham DJ, Kingsley MI, Kilduff LP. Complex training in professional rugby players: influence of recovery time on upper-body power output. J Strength Cond Res 2009; 23: 1780-1785
• 4 Bevan HR, Bunce PJ, Owen NJ, Bennett MA, Cook CJ, Cunningham DJ, Newton RU, Kilduff LP. Optimal loading for the development of peak power output in professional rugby players. J Strength Cond Res 2010; 24: 43-47
• 5 Buddhadev HH, Vingren JL, Duplanty AA, Hill DW. Mechanisms underlying the reduced performance measures from using equipment with a counterbalanceweight system. J Strength Cond Res 2012; 26: 641-647
• 6 Cohen J. A power primer. Psychol Bull 1992; 112: 155-159
• 7 Cormie P, McBride JM, McCaulley GO. Validation of power measurement techniques in dynamic lower body resistance exercises. J Appl Biomech 2007; 23: 103-118
• 8 Crewther BT, Lowe T, Weatherby RP, Gill N, Keogh J. Neuromuscular performance of elite rugby union players and relationships with salivary hormones. J Strength Cond Res 2009; 23: 2046-2053
• 9 Cronin J, McNair PJ, Marshall RN. Developing explosive power: a comparison of technique and training. J Sci Med Sport 2001; 4: 59-70
• 10 Cronin J, Sleivert G. Challenges in understanding the influence of maximal power training on improving athletic performance. Sports Med 2005; 35: 213-234
• 11 Cronin JB, McNair PJ, Marshall RN. Force-velocity analysis of strength-training techniques and load: implications for training strategy and research. J Strength Cond Res 2003; 17: 148-155
• 12 García-Pallarés J, Sánchez-Medina L, Carrasco L, Díaz A, Izquierdo M. Endurance and neuromuscular changes in world-class level kayakers during a periodized training cycle. Eur J Appl Physiol 2009; 106: 629-638
• 13 Gorostiaga EM, Granados C, Ibáñez J, Izquierdo M. Differences in physical fitness and throwing velocity among elite and amateur male handball players. Int J Sports Med 2005; 26: 225-232
• 14 Harriss DJ, Atkinson G. Update – ethical standards in sport and exercise science research. Int J Sports Med 2011; 32: 819-821
• 15 Hori N, Newton RU, Andrews WA, Kawamori N, McGuigan MR, Nosaka K. Comparison of four different methods to measure power output during the hang power clean and the weighted jump squat. J Strength Cond Res 2007; 21: 314-320
• 16 Lawton T, Cronin J, Drinkwater E, Lindsell R, Pyne D. The effect of continuous repetition training and intra-set rest training on bench press strength and power. J Sports Med Phys Fitness 2004; 44: 361-367
• 17 Marques MC, van den Tilaar R, Vescovi JD, Gonzalez-Badillo JJ. Relationship between throwing velocity, muscle power, and bar velocity during bench press in elite handball players. Int J Sports Physiol Perform 2007; 2: 414-422
• 18 Newton RU, Kraemer WJ, Häkkinen K, Humphries BJ, Murphy AJ. Kinematics, kinetics, and muscle activation during explosive upper body movements. J Appl Biomech 1996; 12: 31-43
• 19 Ostrowski KJ, Wilson GJ, Weatherby R, Murphy PW, Lyttle AD. The effect of weight training volume on hormonal output and muscular size and function. J Strength Cond Res 1997; 11: 148-154
• 20 Sanchez-Medina L, Perez CE, Gonzalez-Badillo JJ. Importance of the propulsive phase in strength assessment. Int J Sports Med 2010; 31: 123-129
• 21 Vingren JL, Buddhadev HH, Hill DW. Smith machine counterbalance system affects measures of maximal bench press throw performance. J Strength Cond Res 2011; 25: 1951-1956