Many investigations have examined the power-load relationships in various resistance training exercises (McBride et al., 2011). The primary motivation for this research arose from evidence that training with loads that maximize peak power (PP) have been shown to increase power production capability (Cormie et al., 2007). Power production has been shown to be a key variable in many sporting events and athletic endeavors (Stone, 1993; Zink et al., 2006). While many investigations have examined the power-load relationship in other exercises, only one investigation has established the power-load curve for the deadlift exercise with PP occurring at 30% of one repetition maximum (1RM) (Swinton et al., 2011). However, they neither separated the bar, body, and system (bar + body) nor used a full range of loading intensities (Swinton et al., 2011). Only a few investigations have separated the body, bar, and system (bar + body) for analysis purposes and none have done so for the deadlift (Hori et al., 2007; McBride et al., 2011; Swinton et al., 2011). Results from McBride et al. (2001) indicate that PP occurred at different loads for the bar, body and system depending on which exercise was examined (McBride et al., 2011). For instance in the squat, PP occurred at 90% of 1RM for the bar, 10% of 1RM for the body, and 50% of 1RM for the system. In contrast, jump squat PP occurred at 80% of 1RM for the bar, 0% of 1RM for the body and 0% of 1RM for the system. During the power clean PP occurred at 90% of 1RM for the bar, 90% of 1RM for the body and 80% of 1RM for the system.
Previous research has reported that training at a load that maximizes PP leads to subsequently greater increases in PP after 12 weeks in comparison to other training loads (isotonic, 30%, 60% and 100% PP) (Kaneko et al., 1983). In a subsequent study the same researchers found that training the elbow flexors with 30% and 100% of maximum isometric force improved power more than training with 30% and 0% of maximum isometric force (Toji et al., 1997). The same researchers again observed that elbow flexor power output had greater increases when trained with multiple power loads compared with one power load and one strength load (Toji and Kaneko, 2004). Cormie et al. (2007) found that strength and power training using the jump-squat for 5 sets x 6 repetitions at body mass in addition to a 3x3 at 90% of 1RM exercise improved power across a broader spectrum of the power-load relationship than power training alone using only 7x6 at body mass. Given its' common usage and the lack of research on the topic, determining the loads that maximize PP in the deadlift may be useful for training athletes in order to improve power production across a spectrum of power-load relationships similar to the stimuli an athlete faces on the field (Cormie et al., 2007).
Thus, the primary purpose of this investigation was to determine a more comprehensive power-load curve for the deadlift exercise and to establish the loads that optimize power for the bar, body, and system (bar + body). Establishing loads that optimize bar power might be useful for throwing athletes or weight lifters who move an external mass; whereas, body or system power might be more relevant to sprint athletes or jump athletes who accelerate their own body mass (McBride et al., 2011).
Eight healthy males (age = 22.00 [+ or -] 2.38 years; height = 1.80 [+ or -] 0.05 m; body mass = 88.97 [+ or -] 14.88 kg; deadlift 1RM = 203.44 [+ or -] 21.59 kg, 1RM/BM = 2.32 [+ or -] 0.31) with a minimum of 2 years' resistance training experience, and a deadlift 1RM over 1.5x their bodyweight were recruited for the investigation. Participants completed an informed consent sheet and health screening tool to monitor for any contraindications for participation. The project received approval from the Institutional Review Board at Appalachian State University.
Participants visited the Neuromuscular and Biomechanics Laboratory (NBL) for an orientation and two testing sessions separated by one week. Participants were asked to refrain from performing any type of resistance exercise or strenuous activity 48 hours prior to each testing session. During the first session, anthropometric data (height, weight) was obtained and a 1RM in the deadlift was determined. The warm-up protocol for the 1RM testing involved performing 1 set of 10 repetitions, 1 set of 6 repetitions, and 1 set of 3 repetitions with progressively increasing weight. The participants were then given a maximum of 4 attempts to determine a 1RM (McBride et al., 2011). During the second session, participants performed two repetitions of the deadlift exercise with each load from 30% to 90% of 1RM (in 10% increments). Trials were performed in a randomized fashion utilizing a computer program random number generator. Rest periods of 5 minutes were given between repetitions to minimize the effects of fatigue...