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Weakley, J, Chalkley, D, Johnston, R, García-Ramos, A, Townshend, A, Dorrell, H, Pearson, M, Morrison, M, and Cole, M. Criterion validity, and interunit and between-day reliability of the FLEX for measuring barbell velocity during commonly used resistance training exercises. J Strength Cond Res 34(6): 1519-1524, 2020-The aim of this study was to assess the criterion validity, interunit reliability (accounting for technological and biological variance), and between-day reliability of a novel optic laser device (FLEX) for quantifying mean concentric velocity. To assess the validity against a three-dimensional motion capture system and interunit reliability with both technological and biological variation, 18 men and women completed repetitions at 20, 40, 60, 80, 90, and 100% of one repetition maximum in the free-weight barbell back squat and bench press. To assess interunit (technological only) reliability, a purpose-built, calibrated rig completed a set protocol with 2 devices. To assess between-day reliability of the technology, the same protocol was repeated 21 days later. Standardized bias, typical error of the estimate (TEE; %), and Pearson's correlation coefficient (r) were used to assess validity, whereas typical error and coefficient of variation (CV%) were calculated for reliability. Overall, TEE (±90 CL) between the FLEX and criterion measure was 0.03 (±0.004) and 0.04 (±0.005) m·s in the back squat and bench press, respectively. For measures of reliability, overall interunit technological variance (CV% [± 90% confidence interval]) was 3.96% (3.83-4.12) but increased to 9.82% (9.31-10.41) and 9.83% (9.17-10.61) in the back squat and bench press, respectively, when biological variance was introduced. Finally, the overall between-day reliability was 3.77% (3.63-3.91). These findings demonstrate that the FLEX provides valid and reliable mean concentric velocity outputs across a range of velocities. Thus, practitioners can confidently implement this device for the monitoring and prescription of resistance training loads.

O presente estudo tem como objetivo analisar o efeito do feedback cinemático verbal na atenuação da descida da velocidade concêntrica média (VCM) da barra, medida em metros por segundo (m.s-1), no exercício de agachamento, bem como investigar se diferentes níveis de conscienciosidade acarretam diferentes performances neste parâmetro. Foram incluídos onze atletas adultos, do sexo masculino, com mais de um ano de experiência em crosstraining. Todos apresentavam experiência com o movimento de agachamento. Estes atletas executaram o exercício de agachamento com feedback cinemático verbal (protocolo de feedback), e sem feedback cinemático verbal (protocolo de controlo), na mesma ocasião. A determinação da VCM da barra foi encontrada através de um transdutor linear de posição. Para identificar os níveis de conscienciosidade foi aplicado a todos os participantes a versão portuguesa do inventário de personalidade de 10 itens (TIPI-P), validada por Nunes et al., (2018). Ao comparar o protocolo de feedback com o protocolo de controlo, não se verificaram diferenças estatisticamente significativas na performance do agachamento. Também não foram encontradas diferenças entre os dois protocolos no que diz respeito à atenuação da VCM da barra no exercício de agachamento. Relativamente à relação entre os níveis de conscienciosidade e performance na VCM no exercício de agachamento, não se verificaram diferenças significativas. Conclui-se que a utilização de feedback cinemático verbal não tem um efeito significativo na atenuação da descida da VCM da barra no exercício de agachamento, e que não existe uma relação entre os níveis de conscienciosidade e performance neste parâmetro em atletas adultos do sexo masculino praticantes de crosstraining. This study pretends to analyse the effect of verbal kinematic feedback on the mitigation of barbell velocity drop, measured in meters per second (m.s-1) when performing back squat. The study also aims to investigate the association of different conscientiousness levels and performance on barbell velocity during back squat. Eleven male adult athletes experienced in crosstraining and back squat for more than one year were included. The athletes performed back squat with verbal kinematic feedback (feedback protocol) and without verbal kinematic feedback (control protocol), in the same occasion. The mean concentric velocity of the bar was found through a linear position transducer. To identify the level of conscientiousness, the 10 items portuguese version of the personality inventory was applied to each subject. There were no significant differences in performance when the control and feedback protocols were compared. Similar results were found for both protocols on the mean concentric velocity of the barbell. Regarding the association between conscientiousness and performance on the mean concentric velocity of the barbell when performing back squat, no differences were found. In conclusion the use of verbal kinematic feedback on the mitigation of the barbell velocity drop during back squat had no significative effects, and there was no association between conscientiousness and performance on this parameter in male adults crosstraining athletes.

Sabe-se que os traços de personalidade podem ser preditores do sucesso desportivo e da participação de atletas em atividades físicas. O presente estudo teve como objetivo analisar o efeito do feedback motivacional na velocidade concêntrica média (VCM) da barra no exercício de agachamento em praticantes de crosstraining, bem como avaliar o seu efeito em diferentes níveis de conscienciosidade. Onze atletas adultos do sexo masculino, praticantes de crosstraining, voluntariaram-se para participar neste estudo, que consistiu na execução do movimento de agachamento com e sem feedback motivacional, na mesma ocasião, de forma randomizada. A determinação da VCM da barra foi encontrada através de um transdutor linear de posição. Adicionalmente, os sujeitos preencheram um questionário, antes do estudo, para avaliar os diferentes níveis de conscienciosidade. Os resultados obtidos não apresentaram diferenças significativas (p-value>0,05) quando comparado o protocolo com feedback motivacional com o protocolo de controlo (sem feedback), apesar dos valores da VCM terem sido ligeiramente superiores com a utilização do feedback durante o agachamento (0,62 ± 0,07m.s-1 vs 0,61 ± 0,09m.s-1). Além disso, não foram também encontradas diferenças significativas (p-value>0,05), dentro dos níveis analisados, entre os diferentes níveis de conscienciosidade e a performance na VCM durante o agachamento. Podemos, desta forma, concluir que a utilização do feedback motivacional poderá não ter um efeito positivo em atletas adultos do sexo masculino, praticantes de crosstraining, para potenciar os seus treinos e aumentar a sua performance desportiva It is known that personality traits can be predictors of athletic success and participation in physical activities. The present study aimed to analyze the effect of verbal encouragement on the barbell mean concentric velocity (MCV) during the back squat, in crosstraining athletes, as well as to evaluate the effect on different levels of conscientiousness. Eleven male adult crosstraining athletes volunteered to participate in this study, which consisted of performing the back squat with and without verbal encouragement, on the same occasion, with both sets being randomized. The barbell MCV was found through a linear position transducer. Additionally, the subjects completed a questionnaire, prior to the study, to assess the different levels of conscientiousness. The findings didn’t show significant differences (p-value>0.05) when comparing the verbal encouragement protocol (with feedback) with the control protocol (without feedback). That is, although the MCV values were slightly higher with the use of feedback during the squat (0,62 ± 0,07m.s-1 vs 0,61 ± 0,09m.s-1). In addition, no significant differences were also found (p-value>0.05), within the analyzed levels, between the different levels of conscientiousness and the performance, during the back squat MCV. We can, therefore, conclude that the use of motivational feedback may not have a positive effect on adult male athletes of crosstraining, to enhance their training sessions and increase their sports performance.

Hip thrust (HT) is a loaded bridging exercise that requires more hip extension than a back squat (SQ) does, while in a back squat, triple flex extension occurs. Due to the specificity of each exercise, it is claimed that HT gains can be better transferred to actions where hip extension occurs. In addition, strength improvements during squatting can be transferred in a greater way to vertical plane movement, such as vertical jumping. However, its effects on the performance of female soccer players are unclear. For this reason, the purpose of this study was to analyze a 7-week training program on performance variables using either HT or SQ exercises in female adolescent soccer players without lifting experience (N = 24, age = 16.82 &plusmn, 1.56 years, height = 1.64 &plusmn, 0.55 cm, body mass = 58.35 &plusmn, 6.28 kg). Players were randomized into three groups: A back squat group (SQG, N = 8), hip thrust group (HTG, N = 8), and control group (CG, N = 8). Participants in the HTG and SQG joined a progressive resistance training program twice per week for 7 weeks with either HT or SQ exercises. A countermovement jump, 10&ndash, 20 m sprint, T-test, and barbell velocity during HTs and SQs (with the load that represents ~60 and ~80% RM) were measured before and after the intervention. The HTG showed greater improvements in the 10-m sprint (d = 0.7), 20-m sprint (d = 0.46), T-test (d = 0.36), and barbell velocity at 80% repetition maximal (RM) (d = 0.53) and 60% RM (d = 1.02) during hip thrusts, while the SQG showed higher barbell velocity at 80% RM (d = &minus, 0.7) during back squats. These results may be useful for strength and conditioning coaches working with adolescent female soccer athletes, since both strengthening exercises improved performance in different ways due to the nature of the exercise.

While velocity-based training is currently a very popular paradigm to designing and monitoring resistance training programs, its implementation remains a challenge in team sports, where there are still some confusion and misinterpretations of its applications. In addition, in contexts with large squads, it is paramount to understand how to best use movement velocity in different exercises in a useful and time-efficient way. This manuscript aims to provide clarifications on the velocity-based training paradigm, movement velocity tracking technologies, assessment procedures and practical recommendations for its application during resistance training sessions, with the purpose of increasing performance, managing fatigue and preventing injuries. Guidelines to combine velocity metrics with subjective scales to prescribe training loads are presented, as well as methods to estimate 1-Repetition Maximum (1RM) on a daily basis using individual load–velocity profiles. Additionally, monitoring strategies to detect and evaluate changes in performance over time are discussed. Finally, limitations regarding the use of velocity of execution tracking devices and metrics such as “muscle power” are commented upon. Funding: This research received no external funding.