The purpose of the study was to compare the kinematics of the barbell back squat between two footwear conditions and to evaluate the results with respect to recommendations put forth in the National Strength and Conditioning Association position statement for proper squat technique. Twenty-five subjects with 5 - 7 years of resistance training experience participated. Selected kinematics were measured during a 60% of 1RM barbell back squat in both barefoot and athletic shoe conditions. Paired-samples T tests were performed to compare the two footwear conditions. Significant differences were found in trunk (50.72±8.27 vs. 46.97±9.87), thigh (20.94±10.19 vs. 24.42±11.11), and shank segment angles (59.47±5.54 vs. 62.75±6.17), and knee joint angles (81.33±13.70 vs. 88.32±15.45) at the peak descent position. Based on the kinematic analysis of the barefoot squat, two kinematic advantages are countered by two disadvantages. Coaches and instructors should acknowledge these results with respect to a performer's capability, and be aware the advantages and disadvantages of barefoot squat from a kinematic perspective.

This study examined the postactivation potentiation effects of combining squat and deadlift exercises on subsequent repeated jump performance. Fifteen, resistance-Trained youth wrestlers were randomly allocated to either undertake back squats (BSq), deadlift (DL) or BSq and DL as supersets (BSq+DL), with a repeated jump protocol performed 8-minutes post-exercise in each session. Thereafter, a control condition (CON) was completed involving a general warm-up, followed by the repeated jump protocols. Power outputs, flight time, contact time and reactive strength index were recorded from each repeated jump protocol. Measures were compared between the BSq, DL and BSq+DL sessions and between sessions that generated the best power output (BEST) with CON via inferential statistics and effect size (ES) calculations. The BSq condition exhibited significantly greater power output compared to the CON condition (p0.05, ES = 1.07), although no differences were identified for the other conditioning activities. Furthermore, power output, flight time and reactive strength index were significantly greater for the BEST compared to the CON condition (p0.05, ES = 0.97-1.47). Results indicated that BSq was the optimal conditioning activity to increase power output during a repeated jump protocol. However, greater improvement during the BEST condition suggests that the type of conditioning activity should also be considered on an individual-basis.

The ability to produce power during competition is essential. Football requires explosive power in order to get off the ball faster, increase speed of the first step, and increase the height of the vertical jump. Most strength training professionals use the back squat to increase power of the lower extremities; however, as large forces are placed on the back, athletes are at greater risk for injury. The trap bar dead lift is similar to the back squat in movement and form, but the trap bar dead lift reduces the force on the lower back. After testing for maximum vertical jump,athletes at Timpview High School participated in a strength program using either back squats or trap bar dead lift for seven weeks. A pre-test, mid-test and post-test were performed to calculate the increase in maximum vertical jump, if any. It was found that neither lift was significantly different than the other when testing for maximum vertical jump. These results will allow strength training professionals to use the trap bar dead lift instead of the back squats in subjects similar to those participating in the study.

In sports, peaking phases are often applied prior to important competitions. Peaking phases typically consist of a planned overreach followed by a taper ending with a few days of complete rest. However, during peaking phases, components of body composition such as body mass (BM), fat mass (FM), fat-free mass (FFM), and skeletal muscle mass (SMM) have been shown to be negatively impacted, which could compromise performance outcomes. Thus, the purpose of this study was to monitor body composition prior to and immediately after a peaking phase to determine if body composition changes occurred. Twelve powerlifters completed a seven-week training protocol designed to peak powerlifting performance. The first four weeks consisted of strength training designed to standardize participant training prior to the first testing session (T1). Following T1, the participants performed a one-week overreach followed by a one-week step-taper ending with 2 and 4 days of complete rest followed by a second testing session (T2). Each testing session consisted of a) measuring BM, FM, FFM, and SMM via bioelectrical impedance, and b) 1-repetition maximum (1RM) testing on back squat (BS), bench press (BP), and deadlift (DL). 1RM performances were summed together for a Powerlifting Total (PT), and Wilks Scores were applied to determine relative performance changes. There were no statistically significant changes in BM (p > 0.99), FM (p > 0.99), FFM (p > 0.99), or SMM (p > 0.99), suggesting a maintenance of body composition during the peaking phase. There were, however, statistically significant changes in 1RM-BS (p = 0.04), PT (p = 0.05), and Wilks Score (p = 0.02). These data suggest that two-week peaking phase can result in the maintenance of body composition alongside improvements in strength performance.

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This investigation examined the differences in REACT, RT, and jumping performance for the countermovement jump (CMJ) versus squat jump (SJ) when beginning the movement by responding to auditory (AUD) versus visual (VIS) stimuli. The secondary purposes of this investigation are to examine gender and physical activity level differences of the aforementioned metrics and the relationship between maximal strength, REACT, and RT. Twenty-eight participants (females = 16 and males = 12) were split into three groups (low = 6, moderate = 10, and high = 12) based on their perceived physical activity levels in accordance with ACSM physical activity requirements. Over the course of two days, participants completed an isometric midthigh pull (IMTP), CMJs, and SJs on force plates. Participants jumped as fast as possible upon receiving either an AUD or VIS stimulus in randomized order and without awareness of the stimulus type. Additionally, participants completed maximum voluntary isometric contractions (MVIC) for the tibialis anterior (TA), medial head of the gastrocnemius (GM), rectus femoris, and biceps femoris (BF) of the right leg using Electromyography (EMG) on day two. Participants then completed the CMJ and SJ protocols from day one. The findings revealed that participants displayed significantly faster reaction times (RT) to VIS stimuli than AUD stimuli. Furthermore, RT was faster during the CMJ. The low physical activity group showed faster reaction times during the CMJ. However, no significant differences were observed for the CMJ metric. Significant variations in muscle EMG root mean square (RMS) and mean power frequency (MPF) values were found for both AUD and VIS stimuli during the CMJ phases. Peak propulsive power and jump height (JH) significantly differed during the AUD stimulus for the SJ, while muscle strength did not show a significant correlation with either stimulus. This study highlights the influence of stimulus type and physical activity levels during quick reactions and explosive movements. Training methods and practice tactics may benefit from including visual cues to enhance performance, especially for athletes in sports where rapid visual processing and reaction are critical.

This study examined and compared the acute effects of ballistic and nonballistic concentric-only half-squats (COHSs) on squat jump performance. Fifteen resistance-trained men performed a squat jump 2 minutes after a control protocol or 2 COHSs at 90% of their 1 repetition maximum (1RM) COHS performed in a ballistic or nonballistic manner. Jump height (JH), peak power (PP), and allometrically scaled peak power (PPa) were compared using three 3 × 2 repeated-measures analyses of variance. Statistically significant condition × time interaction effects existed for JH (p = 0.037), PP (p = 0.041), and PPa (p = 0.031). Post hoc analysis revealed that the ballistic condition produced statistically greater JH (p = 0.017 and p = 0.036), PP (p = 0.031 and p = 0.026), and PPa (p = 0.024 and p = 0.023) than the control and nonballistic conditions, respectively. Small effect sizes for JH, PP, and PPa existed during the ballistic condition (d = 0.28–0.44), whereas trivial effect sizes existed during the control (d = 0.0–0.18) and nonballistic (d = 0.0–0.17) conditions. Large statistically significant relationships existed between the JH potentiation response and the subject's relative back squat 1RM (r = 0.520; p = 0.047) and relative COHS 1RM (r = 0.569; p = 0.027) during the ballistic condition. In addition, large statistically significant relationship existed between JH potentiation response and the subject's relative back squat strength (r = 0.633; p = 0.011), whereas the moderate relationship with the subject's relative COHS strength trended toward significance (r = 0.483; p = 0.068). Ballistic COHS produced superior potentiation effects compared with COHS performed in a nonballistic manner. Relative strength may contribute to the elicited potentiation response after ballistic and nonballistic COHS.

The purpose of this study was to compare the temporal profile of strong and weak subjects during ballistic and nonballistic potentiation complexes. Eight strong (relative back squat = 2.1 ± 0.1 times body mass) and 8 weak (relative back squat = 1.6 ± 0.2 times body mass) males performed squat jumps immediately and every minute up to 10 minutes following potentiation complexes that included ballistic or nonballistic concentric-only half-squat (COHS) performed at 90% of their 1 repetition maximum COHS. Jump height (JH) and allometrically scaled peak power (PPa) were compared using a series of 2 × 12 repeated measures analyses of variance. No statistically significant strength level main effects for JH (p = 0.442) or PPa (p = 0.078) existed during the ballistic condition. In contrast, statistically significant main effects for time existed for both JH (p = 0.014) and PPa (p < 0.001); however, no statistically significant pairwise comparisons were present (p > 0.05). Statistically significant strength level main effects existed for PPa (p = 0.039) but not for JH (p = 0.137) during the nonballistic condition. Post hoc analysis revealed that the strong subjects produced statistically greater PPa than the weaker subjects (p = 0.039). Statistically significant time main effects existed for time existed for PPa (p = 0.015), but not for JH (p = 0.178). No statistically significant strength level × time interaction effects for JH (p = 0.319) or PPa (p = 0.203) were present for the ballistic or nonballistic conditions. Practical significance indicated by effect sizes and the relationships between maximum potentiation and relative strength suggest that stronger subjects potentiate earlier and to a greater extent than weaker subjects during ballistic and nonballistic potentiation complexes.