A Biomechanical Comparison of the Back Squat and Hexagonal Barbell Deadlift.

ABSTRACT: Stahl, CA, Regni, G, Tanguay, J, McElfresh, M, Trihy, E, Diggin, D, and King, DL. A biomechanical comparison of the back squat and hexagonal barbell deadlift. J Strength Cond Res 38(5): 815-824, 2024-Coaches often use different exercises to encourage similar strength adaptations and limit monotony. Anecdotally, the hexagonal barbell deadlift (HBD) exhibits similarities to the back squat (BS). To date, research has not examined the empirical differences between these exercises. This study examined kinematic and kinetic differences between the BS and the HBD across different loads. Sixteen resistance-trained individuals (6 men and 10 women) volunteered to participate. Subjects performed 1-repetition maximum (1RM) testing under BS and HBD conditions. Kinematic and kinetic data were collected during performance of both exercises at submaximal (warm-up sets) and maximal (1RM) loads using a 3D motion capture and force-plate system. Results showed that subjects lifted greater 1RM loads in the HBD relative to the BS (p < 0.05; d = -1.75). Kinematic data indicated that subjects exhibited greater maximum forward lean of the trunk and decreased maximum knee flexion while performing the HBD compared with the BS. The BS resulted in higher maximum extension moments at the hip joint than the HBD. Maximum extension moments at the knee joint showed no difference between the exercises. Data suggest that bar design and position facilitate balanced moment arm length at hip and knee joints during performance of the HBD. By contrast, bar position during performance of the BS increases moment arm length at the hip joint, making it a hip-dominant exercise. The present data have implications for the programming of both exercises. Future research should examine differences in muscle-activation strategies between the 2 exercises.

Descriptive and Kinetic Analysis of Two Different Vertical Jump Tests Among Youth and Adolescent Male Basketball Athletes Using a Supervised Machine Learning Approach.

ABSTRACT: Gillett, J, De Witt, J, Stahl, CA, Martinez, D, and Dawes, JJ. Descriptive and kinetic analysis of two different vertical jump tests among youth and adolescent male basketball athletes using a supervised machine learning approach. J Strength Cond Res 35(10): 2762-2768, 2021-The countermovement jump (CMJ) is a functional movement in basketball and is also frequently used as an assessment of lower-body power. The CMJ can be performed in a variety of manners, and multiple variables can be extracted, and calculated, from the ground reaction force (GRF) time curve. The purpose of this article is to present kinematic and kinetic data collected from adolescent male basketball players during performance of the CMJ with hands on hips (HOH) or with an arm swing while reaching overhead to a target (i.e., vertical jump reach [VJR]). This study also sought to determine the effectiveness of a machine learning algorithm to identify the most important features that relate to jump height. Bilateral GRF data were collected on 89 right-handed male basketball athletes (age: 13.19 ± 0.72 year old, mass: 60.44 ± 13.35 kg, standing reach height: 228.49 ± 16.79 cm) using force platforms (Forcedecks, Vald Performance, Newstead, Queensland, Australia) and their associated software. Fifty-six bilateral kinematic and kinetic variables from each condition were analyzed using supervised machine learning to identify the top 10 important features to predict jump height in each condition, and to predict VJR height using HOH data. Vertical center of mass flight height was greater during VJR trials than during HOH trials (38.9 ± 6.8 cm vs. 32.6 ± 5.5 cm, respectively). The only common predictor variables between the conditions were concentric impulse and peak power. HOH jump data were able to predict VJR height with a mean error of 7.13 cm. These data suggest that important force platform data relating to jump height differ depending on test condition, and that data from CMJ performed with HOH, particularly peak power, concentric impulse, and concentric rate of power development, can be used to predict jump height during functional performance.

Stress in Academic and Athletic Performance in Collegiate Athletes: A Narrative Review of Sources and Monitoring Strategies.

College students are required to manage a variety of stressors related to academic, social, and financial commitments. In addition to the burdens facing most college students, collegiate athletes must devote a substantial amount of time to improving their sporting abilities. The strength and conditioning professional sees the athlete on nearly a daily basis and is able to recognize the changes in performance and behavior an athlete may exhibit as a result of these stressors. As such, the strength and conditioning professional may serve an integral role in the monitoring of these stressors and may be able to alter training programs to improve both performance and wellness. The purpose of this paper is to discuss stressors experienced by collegiate athletes, developing an early detection system through monitoring techniques that identify the detrimental effects of stress, and discuss appropriate stress management strategies for this population.

A Comparison of Lower Body Power Characteristics Between Collegiate Athletes from Different Competition Levels.

The counter-movement jump (CMJ) is frequently utilized by strength and conditioning professionals working with athletes, given its relationship to a multitude of performance variables associated with success in sports. PURPOSE: To examine characteristics of CMJ performance between NAIA and NCAA Division I male and female athletes. METHODS: Archival data for 275 student athletes from two NCAA Division 1 universities (NCAA DI; males = 84, females = 74) and one NAIA university (NAIA; males = 66, females = 51) were utilized for this analysis. The CMJ was performed utilizing a dual single axis (Pasco PS 2141 plates, sampling rate 1000hz unfiltered) force platform system. A 2 × 2 multivariate analysis of variance (MANOVA) was used to determine whether significant differences in the three dependent variables of VJ height (cm), concentric RPD-100ms, and peak power existed between athletes at different playing levels. RESULTS: A MANOVA revealed significant differences based on sex and competition level in the dependent variables measured (Wilk's Lambda = 0.908, F(3,259) = 8.732, p < .001, partial η2 = .092). DISCUSSION: The findings of this study revealed that females at the Division I level achieved significantly greater jump heights, peak power and concentric RPD-100ms compared to females at the NAIA level. Division I males displayed significantly higher peak power than their NAIA counterparts.