The conventional deadlift (CD) performed with an Olympic bar is a popular strength exercise that targets the leg, hip, back, and torso musculature (8,15,35). Use of this exercise has contributed to improvements in lower-body strength across different populations (39,42,44), which provides validation for its use in resistance training. However, the CD can be difficult for some individuals because of physical limitations (15). Indeed, body height, arm length (AL), and leg length (LL) can all influence how an individual performs the CD (15,27). This formed part of the reason as to why the hexagonal bar was designed (40). The hexagonal bar, which can feature high and low handles (Figure 1), allows the lifter to keep the load closer to the body during the deadlift exercise, as they lift within a frame (4,11,40,41).
When compared with the CD, the hexagonal bar deadlift resulted in less bar displacement (40), changes to the lifting technique (26), and muscle activation patterns (4). Anecdotal information has suggested that the hexagonal bar deadlift could be beneficial for taller individuals because the set-up position is easier to attain (12,36) and requires a more upright trunk position (i.e., less trunk flexion) at liftoff (25,43). The high-handle hexagonal bar deadlift (HHBD) should make it even easier for the taller individual to position themselves within the bar frame because the handle position could further reduce the resistance moment arm at the lumbar spine (40). Lockie et al. (25) suggested that a more advantageous lifting position provided by the HHBD resulted in greater peak power, velocity, and peak and mean force in a 1 repetition maximum (1RM) lift when compared with the CD. However, Lockie et al. (25) found that because of a greater lift distance, greater work was performed in the 1RM CD. An individual's anthropometry, such as AL and LL, could also influence factors such as lift distance and duration, and by extension, the work performed during the lift. Given that total work performed during resistance training sets may be the most valid way to measure strength training load (29), this is notable. However, no research has investigated the relationships between height, AL, and LL on the mechanics of the HHBD, and whether this differs to the CD.
Indeed, there is little research that has investigated the influence AL and LL may have on the performance of strength exercises (28). It has been anecdotally believed that individuals with a longer AL relative to LL (AL:LL ratio) may have better deadlifting ability (27). Mayhew et al. (28) found that a shorter LL had a positive effect on CD when performed by collegiate football players; however, information about the mechanics of the lift (i.e., power, velocity, force, and work) was not provided. By contrast, Mayhew et al. (27) illustrated that AL, LL, or AL:LL did not correlate with the CD performed by novice adolescent powerlifters. After a review of literature, Pereira and Gomes (34) suggested that anthropometry was a poor predictor of 1RM for most strength exercises. Arm length and LL, however, may be more of an influence on lift mechanics when performing the HHBD, where the handles are in a fixed position. Nonetheless, there is currently no research that has investigated the relationships between height or limb length and the HHBD.
Furthermore, there could be differences between the sexes with how limb length may influence the mechanics of the CD and HHBD. About the HHBD, a shorter AL could affect lift mechanics because the arms will need to be abducted further from the body to grip the bar handles. This may reduce lift distance, and reduced lift distance in the HHBD can cause changes to the power, velocity, force, and work performed (25). This could be more evident in women because women tend to have a smaller body size when compared with men (10,22). The hexagonal bar has a set design and distance between the handles, which may not be optimal for individuals of a smaller body size, which could affect women more than men. Furthermore, Fuster et al. (10) also found that body height correlated with pulling strength in collegiate-aged women but not men. As a result, the authors concluded that body size in women was a determining factor in pulling strength. The results from Fuster et al. (10) underscore that there could be differences between the sexes as to the relationships between height, AL, LL, and AL:LL during the CD and HHBD. This could be exacerbated in the HHBD because of the set design of the bar. Further research is needed to confirm this hypothesis because an individual's AL and LL could influence the power, velocity, and force profile of these lifts, in addition to the work performed during a resistance training session. This could then influence any resulting long-term adaptations from the CD or HHBD.
Therefore, this study investigated relationships height, AL, LL, and AL:LL with the mechanics of the 1RM CD and HHBD. Resistance-trained men and women were recruited and analyzed separately. The procedures used in this study were similar to that used in the study by Lockie et al. (25). The mechanics of the CD and HHBD were both measured through a linear position transducer, which was used to ensure that the recorded data would have practical value to the strength and conditioning coach because this equipment is used extensively in the field (6,16,25). It was hypothesized that greater height, AL, and LL would relate to a greater bar displacement for both men and women, which would also result in greater work being performed. Specific to the HHBD, it was further hypothesized that these relationships would be more pronounced for men because AL would have less impact in women because of the fixed handle width. Last, it was hypothesized that men and women with a higher AL:LL (i.e., longer arms relative to the legs) would generate greater peak power, force, and velocity in both the CD and HHBD.
Experimental Approach to the Problem
A cross-sectional analysis of resistance-trained men and women was conducted to investigate the relationships between body height, AL, and LL on the mechanics of the CD and HHBD. All data for the CD and HHBD were recorded by a linear position transducer. Within 1 testing session, subjects had their height, AL, and LL measured before they performed the 1RM CD and HHBD in a randomized order. The dependent variables included: height, AL, LL, and AL:LL ratio; 1RM load for the CD and HHBD, and relative strength derived from both of these lifts; lift distance and duration; peak and mean power and velocity, and the relative time at which peak power and velocity occurred within the lift; peak and mean force; and work.
Twenty-three resistance-trained individuals (± SD age = 22.48 ± 1.38 years [all subjects were 18 years or older]; height = 1.73 ± 0.12 m; and body mass = 76.81 ± 17.77 kg), including 14 men (age = 22.43 ± 1.51 years; height = 1.80 ± 0.09 m; and body mass = 87.36 ± 14.20 kg) and 9 women (age = 22.56 ± 1.24 years; height = 1.62 ± 0.06 m; and body mass = 60.40 ± 6.59 kg), volunteered to participate in this study. G*Power software (v126.96.36.199; Kiel University, Kiel, Germany) confirmed post hoc that the male sample size of 14 was sufficient for a correlation, point biserial model, and ensured the data could be interpreted with a moderate effect level of 0.65 (17) and a power level of 0.84 when significance was set at 0.05 (9). The female sample size of 9 meant data could be interpreted with a moderate effect level of 0.70 (17) and a power level of 0.71 when significance was set at 0.05 (9). Subjects were recruited from the student population at the university in which the study was approved. All subjects were required to be currently resistance training (≥3 hours per week) with a focus on either hypertrophy or maximal strength development; have a strength training history (≥2 times per week) of at least 2 years and be experienced with completing maximal lifts; be experienced with the CD and HHBD; and free from any musculoskeletal disorders that would influence their ability to participate in this research. Similar to Lockie et al. (25), subjects were defined as being strength-trained, without being elite or competitive strength athletes (e.g., powerlifters or Olympic lifters). The institutional ethics committee of California State University, Northridge approved the procedures used in this study. All subjects received a clear explanation of the study, including the risks and benefits of participation, and written informed consent was obtained before testing.
The procedures used for this study have been detailed by Lockie et al. (25). One testing session was completed by all subjects, with all assessments conducted in the university strength laboratory. Before data collection, the subject's age, height, body mass, AL, and LL were recorded. Height was measured barefoot using a portable stadiometer (seca, Hamburg, Germany). Body mass was recorded by electronic digital scales (Tanita Corporation, Tokyo, Japan). The right arm and right leg were used for the AL and LL measurements, respectively (33). A thin-line metric tape measure (Lufkin, Apex Tool Group, MD, USA) was used to take these measurements. Arm length was measured as the distance from the acromion of the scapula, which was determined by palpation, to the tip of the middle fingertip (3,45). As per Young and Pryor (45), the AL measurement was taken while the subject held their arm extended and parallel to the ground. Leg length was measured when subjects were laying supine on a portable plinth. Using the procedures detailed by Beattie et al. (1), LL was measured as the distance from the anterior superior iliac spine to the medial malleolus. The ratio between AL and LL was expressed as a percentage and calculated by the formula: AL:LL = (AL·LL−1) × 100 (27).
The 1RM CD and HHBD were both assessed within 1 session, and the order of the strength tests was randomized among the sample through the randomization function in a Microsoft Excel spreadsheet (Microsoft Corporation, Redmond, WA, USA) (25). Subjects refrained from intensive lower-body exercise and maintained a standardized dietary intake in the 24-hour period before testing and consumed water as required throughout the testing session. The subjects wore the footwear they were most comfortable in to complete the lifts (i.e., weightlifting or running shoes), and the same footwear was worn for both lifts. No other supporting garments, such as knee wraps or weight lifting belts, were permitted.
Conventional Deadlift and High-Handle Hexagonal Bar Deadlift Maximal Strength Testing
The procedures for the 1RM CD and HHBD have been presented by Lockie et al. (25). The lifts were performed on an Olympic lifting platform. The CD was performed with an Olympic bar, whereas the HHBD was performed with a dual-height hexagonal bar (American Barbell, San Diego, CA, USA). The distance between the center of the low and high handles was 0.10 m, whereas the distance between the centers of the 2 high handles was 0.64 m. As stated, the testing order for the CD and HHBD was randomized; the methods in this study will describe the process if CD was completed first.
The CD 1RM was performed as previously described in the literature (14,25,37). Subjects initially completed a general warm-up of 5 minutes cycling on a bicycle ergometer at a self-selected intensity, followed by a dynamic stretching routine that was self-selected and lasted for approximately 10 minutes. Four specific warm-up sets were then completed, with 3-minute recovery between each set. These sets were composed of 10 repetitions at 50% of estimated 1RM by the subject, followed by 5 repetitions at 70% of 1RM, 3 repetitions at 85% 1RM, and 1 repetition at 90% 1RM. After the warm-up sets, the weight was increased by approximately 5%, and subjects completed a single repetition. This process continued until the subjects were unable to complete a repetition, with 3-minute rest provided between attempts. Subjects were instructed to lift the bar with as much force as possible (25). A successful repetition was attained when the subject was standing with their shoulders positioned behind the vertical orientation of the bar (37), which was determined by an investigator positioned adjacent to the subject (25). This position was attained through the subject extending the knees, retracting the shoulders, and standing erect (25,40). If the subject did not attain this position, or if the bar was lowered at any point during the ascent, the lift was deemed unsuccessful (25,40). Subjects could self-select their preferred grip but were not permitted to use a sumo stance (i.e., the hands on the bar had to be positioned outside the legs). Not more than 5 attempts were required before the 1RM was attained.
After completion of the 1RM testing for the CD, subjects rested for 10 minutes before attempting the HHBD. The warm-up for the second lift involved completing 3 sets; 5 repetitions at 70% of the estimated 1RM, 3 repetitions at 85% 1RM, and 1 repetition at 90% 1RM. The initial, higher repetition warm-up was foregone in the second exercise because the subjects were already warm from the first exercise (13,25), and 3-minute recovery was provided between sets. The same loading procedures that were used for the CD 1RM attempts were also used for the HHBD. The body position that was required for a successful CD was also required for the HHBD, except that the subject was standing erect within the frame of the hexagonal bar (25). Identical to Lockie et al. (25), the deadlift testing order was randomized; thus, certain subjects performed the HHBD first. In addition to the absolute load for both lifts, the 1RM was also calculated relative to body mass according to the formula: relative 1RM (kg·BM−1) = 1RM·body mass−1.
Data were recorded during the CD and HHBD by a GymAware Powertool linear position transducer (Kinetic Performance Technology, Canberra, Australia). For the CD, the external end of the cable was attached on the inside of the barbell (i.e., inside the sleeves and on the outer part of the grip section of the bar; Figure 1A) (25). The cable was attached to the front of the hexagonal bar for the HHBD (Figure 1B) (25). The unit was then placed on the floor directly underneath the attachment point, with the magnetic bottom positioned on top of a weight plate to ensure it did not move during each lift (7,25). The encoder recorded velocity and the movement of the bar at 50 Hz for every 3 mm of bar movement (7). Data for each 1RM attempt were collected and stored on an iPad handheld device (Apple Inc., Cupertino, CA, USA) before being uploaded to an online database. The data were then exported into Microsoft Excel before statistical analyses.
The variables recorded from the GymAware software were similar to those from Lockie et al. (25). These included lift distance (i.e., displacement of the bar from lift initiation to lockout) and lift time in seconds. Because a maximal deadlift only features a concentric phase (30), only concentric variables were considered (25). These included peak and mean power (W) and velocity (m·s−1), and the relative time (%) when it occurred during the lift; peak and mean force (N); and work (J). Power, force, and work were derived relative to the load on the bar, which was entered into the GymAware software. All the performance variables measured by the equipment used in this study have been shown to be reliable and valid (2,6,19,25).
All statistical analyses were computed using the Statistics Package for Social Sciences (version 24.0; IBM Corporation, New York, NY, USA). Descriptive statistics (mean ± SD; 95% confidence intervals) were calculated for each variable. The normality of the data was assessed by visual analysis of Q-Q plots (32). Stem-and-leaf plots were used to ascertain whether there were any outliers in the data for each variable. Any outliers were treated through a winsorization method (21,25), and men and women were analyzed separately. Because of the sample size of the male (n = 14) and female (n = 9) groups (23,24), Spearman's correlations were used to determine relationships between height, AL, LL, and AL:LL with the mechanics of the CD and HHBD. Significance was set as p ≤ 0.05. The strength of the correlation coefficient (ρ) was designated as per Hopkins (18). A ρ value between 0 to 0.30, or 0 to −0.30, was considered small; 0.31 to 0.49, or −0.31 to −0.49, moderate; 0.50 to 0.69, or −0.50 to −0.69, large; 0.70 to 0.89, or −0.70 to −0.89, very large; and 0.90 to 1, or −0.90 to −1, near perfect for relationship prediction.
The men had a mean AL of 0.75 ± 0.04 m, LL of 0.94 ± 0.05 m, and AL:LL of 80.15 ± 2.01%. The women in this study had a mean AL of 0.68 ± 0.03 m, LL of 0.85 ± 0.04 m, and AL:LL of 79.63 ± 1.48%. The 1RM, relative strength, lift distance, and lift time descriptive data for the CD and HHBD for both sexes are shown in Table 1, whereas the mechanics data are displayed in Table 2. Table 3 shows the correlation data for men. For the CD in men, there was a large, positive relationship between height and lift distance. Arm length positively related to peak power (large), mean force (very large), and work (large). Leg length positively correlated with peak and mean force (both large) and work (very large). Height also correlated with lift distance for the HHBD, which was a very large relationship. Arm length did not significantly relate to any HHBD variable. Leg length had a large negative relationship with relative strength and large positive relationships with lift distance, mean power, and work. Arm length:leg length ratio exhibited very large negative relationships with lift time, and the time at which peak power and velocity occurred.
The correlation data for the women are displayed in Table 4. For the CD, large negative relationships were found between height, AL, and LL with relative strength, whereas positive relationships were found for height (large), AL (near perfect), and LL (very large) with lift distance. About the HHBD, height had a near perfect relationship with lift distance, whereas AL and LL both had large relationships with this variable. Arm length had a significant, negative relationship with lift time, which was very large. Height (large), AL, and LL (both very large) also had significant positive relationships with mean velocity.
This is the first study to investigate the relationships between height, AL, LL, and AL:LL ratio with the HHBD and compare these relationships with the CD. Furthermore, this study also investigated men and women separately to ascertain whether there were any sex differences as to the influence of height, AL, LL, and AL:LL ratio on the CD and HHBD. The results indicated that there were selected differences between the sexes for the potential influence of AL and LL on the mechanics of the CD and HHBD. These primarily related to lift distance and the force and work generated during the CD and HHBD. Nevertheless, there were limited relationships between AL and LL with power and velocity in the CD and HHBD for both men and women. The results from this study have implications for strength and conditioning coaches regarding how they may monitor the load associated with the CD and HHBD when performed by men and women of different body sizes.
In support of the studies' hypotheses, height related to lift distance for the CD in men, although there were no significant relationships with AL or LL. This contrasts the findings of Fuster et al. (10), who found that height did not relate to isometric pulling strength in collegiate-aged men. Leg length also positively correlated with the absolute load for the 1RM CD. In strength-trained men, larger individuals can often lift heavier absolute loads in strength tests (20), which highlight how this relationship may have occurred. Furthermore, mean force correlated with height, AL, and LL and work correlated with AL and LL. The further a bar travels during a lift results in more work being performed and the more force that needs to be applied during the lift (25,29). This demonstrated why there were relationships between AL and LL with mean force and work in this study. For strength and conditioning coaches, they should be aware that men with longer limbs will likely need to complete more work during a maximal CD. This could influence how a coach programs this exercise when they are training male athletes with a range of body sizes. Given the value of using total work to measure strength training load (29), coaches should carefully monitor the work performed during the CD for taller athletes, especially if they are attempting to equate load across a team.
There were very few significant correlations between height, AL, LL, and AL:LL ratio with the lift mechanics for the CD performed by women. However, greater relative strength related to shorter body heights, AL, and LL. These results indicated that the shorter women in this study lifted a heavier 1RM CD relative to their body mass. This is similar to what has been recorded for strength-trained men (5,20), and relative strength is also an important metric for female athletes (31). In addition, greater height, AL, and LL related to greater lift distances. Fuster et al. (10) illustrated that height significantly related to pulling strength in collegiate-aged women in their study (ρ = 0.27), although the relationship was stronger in this study (ρ = 0.67). Similar to men, taller women and women with longer arms and legs will be required to move the bar a further distance in the CD. However, this did not translate to increased work. Work is calculated for strength training repetitions by multiplying the load by the distance it travels (29). Potentially, the taller women and those with longer limbs may not have lifted a heavy enough load for this to translate to increased work.
About the HHBD performed by men, both height and LL correlated with lift distance and the correlation between height and lift distance was very large. However, peak or mean force did not correlate with height or limb length, and only LL correlated with work. The influence of AL may be reduced for men when using the high handles in the HHBD because the handle position is fixed, which means the arms must be abducted at the shoulders for the individual to grip the bar (as opposed to being held at the side of the body in the CD). There was also a negative relationship between height and relative strength measured from the HHBD, which suggested shorter men demonstrated greater relative strength. This is typical of strength tests in trained male populations, where athletes of smaller body sizes can demonstrate higher relative strength (5,20). However, similar to the CD, men with longer legs may need to complete more work when performing the HHBD. In addition to this, there were negative relationships between AL:LL ratio and lift time and the time when peak power and velocity were achieved. These relationships suggested that a higher AL:LL ratio (i.e., longer arms relative to the legs) related to a shorter lift time, with peak power and velocity reached earlier in the lift. A higher AL:LL ratio has been related to the ability to complete the CD (27), and the results from this study provide some credence to this concept. Reaching peak power and velocity sooner may assist in reducing the time needed to complete the HHBD, which highlights potential benefits for those men with a higher AL:LL ratio.
For the HHBD performed by the women, there were no significant correlations between height, AL, or LL with 1RM and relative strength. This may have been influenced by the smaller sample size of women (n = 9) in this study. However, greater height, AL, and LL did relate to a longer lift distance. In addition to this, there was a negative relationship between AL and lift time, which suggested that a longer AL related to a shorter lift time. This was different to the men in this study and may relate to the advantages of performing a deadlift exercise with relatively longer arms because this can reduce the time and distance over which the bar needs to travel (27). Furthermore, the effect of AL on the HHBD may be exacerbated for women. Because women tend to have a smaller body size when compared with men (10,22), and the dimensions for the hexagonal bar are fixed, the lifting position for smaller women may be less than optimal. As a result, women with a smaller AL may need to abduct their arms further to grip the bar, which could then mean the lift duration will be increased in a 1RM HHBD. Given that certain Olympic bars have been specifically designed for women, manufacturers should also consider designing sex-specific hexagonal bars. Last, greater height, AL, and LL all related to a higher mean velocity in the HHBD. Because the bar needed to travel further in the HHBD for taller women and those with longer limbs, this could have meant velocity needed to be maintained through the duration of the lift.
There were few significant correlations for CD and HHBD peak and mean power and velocity for either the men or women (apart from the relationships between HHBD mean velocity with height, AL, and LL for the women). Indeed, the only other significant relationship was the correlation between AL and CD peak power for the men. The ability to generate high lower-body power is necessary for many athletes, and deadlift exercises can be prescribed to achieve this adaptation (39,42,44). Achieving high power and velocity in strength exercises require a great rate of force development, which is dependent on the neuromuscular characteristics of the individual (38). As a result, even if the bar in the CD or HHBD needs to travel further because of the height, AL, or LL of the individual, high power and velocity can still be generated if the individual has the requisite neuromuscular coordination and rate of force development.
There are several limitations for this study that should be noted. The sample size for both men (n = 14) and women (n = 9) in this study was relatively small. Future investigations into the relationships AL and LL may have on strength exercises such as the CD and HHBD should attempt to use a greater sample size. The low-handle hexagonal bar deadlift was not investigated in this study. Given that previous research has also shown differences in the technique of this exercise compared with the CD (4,26,40), future research could investigate the relationships that height, AL, and LL may have on the mechanics of the low-handle hexagonal bar deadlift. The biomechanics of the HHBD, and how height, AL, and LL may influence this, were also not investigated in this research. Although that was not the focus of this study, it would be interesting to measure how an individual adapts their lifting technique in an exercise like the HHBD relative to their AL and LL. Nonetheless, this is the first study to investigate the effects of height, AL, and LL on the mechanics of the CD and HHBD, and whether there were differences between the sexes. Height and LL influence lifting distance for men and women in both the CD and HHBD. Arm length also related to lift distance in the CD for women. Men with longer limbs will likely complete more work in the CD, and those with longer legs will complete more work in the HHBD. For women, longer legs did not relate to work in the CD, but longer legs could result in more work performed in the HHBD.
Strength and conditioning coaches should be cognizant of the impact that height, AL, and LL can have on the performance of the CD and HHBD. Men with longer limbs will need to generate more force and do more work to complete a 1RM CD. In the HHBD, it seems that the influence of AL on men is reduced when using the high handles. Nonetheless, men with longer arms and shorter legs will reach peak power and velocity sooner in the HHBD. Men with longer legs, however, may need to complete more work during the HHBD. Strength and conditioning coaches should consider the discrepancies in the work needed to complete a deadlift when programming among a sample of men of different sizes. For women in the CD, those with longer arms and legs will lift the bar a greater distance, but limb lengths do not seem to greatly relate to the mechanics of the 1RM. For the HHBD, greater AL and LL related to greater lift distance, longer lift duration, and higher mean velocity throughout the 1RM lift. Unlike for the men, AL in women did seem to influence the lift distance and duration of the HHBD, which could be due to the design of the bar frame because it may not be optimal for smaller women. Coaches should consider this when programming the HHBD for women with different body sizes. Furthermore, because of the discrepancies in size between men and women (10,22), manufacturers should consider designing a female-specific hexagonal bar for use in strength training.
The authors acknowledge their subjects for their contribution to this study. The authors also thank Ibett Torne, Megan Beiley, and Jillian Hurley for assisting with data collection. This research project received no external financial assistance. The authors have no conflicts of interest to disclose.
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