Over the years we have seen lifters pulling with and without shoes. Taking away those few millimeters brings a lifter closer to the floor/bar, which decreases the overall distance traveled for the load. Mechanically speaking, this would decrease the overall work being performed, since work = force*distance.
This study sought out to determine the effects on force and power production between shod and barefoot lifters in the conventional deadlift. “It was hypothesized that a deadlift in an US (unshoed) condition would provide a higher magnitude of PF (peak vertical ground reaction force), PP (peak power), RFD (rate of force development) and a reduced COP (center of position) excursion on the ML and AP axes when compared with a shod condition.”
10 male participants (age mean = 27.0 ± 5.8 years (range: 20–33 years), body mass = 78.7 ± 11.5 kg, height = 175.8 ± 8.2 cm, and 1RM = 155.8 ± 25.8 kg) volunteered for this study. All subjects have been training the conventional deadlift at near maximal loads for at least two years.
On the first session, a 1RM deadlift was recorded. The two following sessions were trial sessions testing either shoed (S) or US conditions. After a warm-up on the cycle ergometer for approximately 8 minutes, each subject followed a standardized barbell warm-up. Subjects used a pronated grip, completing 4 reps at 60% and 80% 1RM with or without shoes.
The trial procedures were as follows: “a) 5–10 repetitions with a 20 kg bar; followed by time to load bar; (b) 5–6 repetitions at 50% of their first experimental load (i.e., approx. 30% of 1RM) followed by 1-minute rest; (c) 4 repetitions at 60% of 1RM followed by 3 minutes rest; and (d) 4 repetitions at 80% of 1RM followed by 5 minutes rest. After this rest period, participants completed the lifting sequence as identified in points (c and d) above, in the second experimental condition.”
The US condition appeared to significantly enhance RFD (F = 6.389; p = 0.045; hp2 = 0.516) and decrease the ML-COP (F = 6.696; p = 0.041; hp2 = 0.527). When measuring differences between TPF, PP, or AP-COP effects were insignificant (F range from 0.270 to 4.567; p range from 0.618 to 0.076).
The primary finding was the significantly higher RFD in the US vs S condition, at both 60% and 80% 1RM. It has been hypothesized that a shod lifter may lose the ability to quickly exert force into the ground from the slight instability of a shoe. Also, the medio-lateral stability is significantly enhanced while deadlifting without shoes. These notions would be supported by this study. Therefore, it may be ideal to train above 60% unshod, if RFD and velocity are of emphasis in a particular training phase.
Trying to find a reliable correlation between a dry-land strength and swim performance can be a tricky task. Previous literature has drawn weak comparisons to the bench press, lat pulldown, and jumping ability. “It has been shown that the leg kick supplies 30% of the total forces produced during sprint swimming.” Therefore, sprint swimmers may best be assessed on dry-land by an upper extremity pulling exercise. The purpose of this paper was “…to analyze whether performance in common dry-land exercises such as the pull-up and the countermovement jump (CMJ) could be valid predictors of swimming performance.”
Subjects included 12 male swimmers ages 16-29 years (mean age of 19 ± 3 years, height of 180cm ± 6cm, weight of 75kg ± 10kg, 15% ± 3% body fat mass). The primary inclusion criteria was that all subjects have had to have competed at a regional level and must be able to swim a 50m freestyle in less than 30 seconds (50-m freestyle: 26.41 ± 1.44 seconds, coefficient of variance: 5.5%).
Lower-limb Testing: Two CMJ tests were performed with the subjects instructed to keep both hands on their hips while trying to reach their peak height. The first was a series of 5 attempts, with 1-minute recovery between attempts, where the 3 median heights were averaged for the mean height (CMJH) . The second was a series 30 consecutive CMJs, separated by 2 seconds between each attempt via acoustic signal. “The mean height (CMJMH) during this test and the relative loss—expressed as a percentage—between the mean height reached in the first and the last 15 jumps (CMJHL) were determined.”
Upper-limb Testing: Two different pull-up tests were performed. All repetitions were performed with a pronated grip, beginning with elbows fully extended. Similarly, 5 pull-ups were performed with 1-minute recovery between attempts, where the 3 median velocities were averaged for the mean pull-up velocity (PUV) using a linear force transducer. “The mean velocity (PUV), the absolute (PUAF) and relative force (PURF), and the absolute (PUAP) and relative power (PURP) were determined, as well as the peak velocity (PUPV) and the time to reach it (PUTpV).” 15 minutes later, each participant performed pull-ups until volitional muscle fatigue (PUF).
Swimming Performance: One-hour post-dry-land testing, subjects swam a maximal 50m freestyle for time. A day later the subjects swam another legs-only 50m swim using a kickboard. A camera assessed to determine the stroke frequency (SF) during the 50-m freestyle test and the relative stroke frequency loss (SFL) between the first and last 25 m.
“As can be seen, different upper-limb explosive strength markers such as PUV (0.78 ± 0.18 m/s), PUAP (637 ± 197W, Figure 1B), PURP (8.48 ± 2.24 W/kg), and PURF (10.76 ± 0.33 N/kg) were significantly correlated with 50F (26.41 ± 1.44 seconds). “
“As for the fatigue resistance indexes of the upper limbs, a strong correlation (Table 1) was found between 50F and PUFV (0.57 6 0.15 m/s, Figure 2A) and PUFVL (26.4 6 6.7%, Figure 2B)…”
“No significant relationship was found between measures of lower-limb strength values assessed through the CMJ tests and swimming performance…”
The primary findings are that there seems to be a strong correlation between the velocity and power displayed during a single pull-up as well as during PUF (consider the resistance to loss of velocity throughout set to failure). It is key to realize that max number of pull ups (or any CMJ data) was not a predictor of swim performance, but rather maintaining a similar concentric pull-up velocity during a set to failure.
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