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Journal of Strength and Conditioning Research

Austyn L Nealer, Dustin D Dunnick, Kylie K Malyszek, Megan A Wong, Pablo B Costa, Jared W Coburn, Lee E Brown
Speed is a crucial element an athlete must possess to be successful. In soccer, the ability to accelerate faster than your opponent can result in being first to reach a ball on a breakaway or stopping a counter attack. A unique way to train explosive movements is to evoke postactivation potentiation (PAP) in the working muscles. Traditionally, an overload stimulus with a long rest period is used, but a model utilizing an overspeed stimulus with shorter rest periods is less understood. Therefore, the purpose of this study was to determine the acute effects of varied rest intervals following assisted sprinting on bodyweight sprint time...
October 6, 2016: Journal of Strength and Conditioning Research
Josué Gómez-Molina, Ana Ogueta-Alday, Christopher Stickley, Jesus Camara Tobalina, Jon Cabrejas-Ugartondo, Juan García-López
The aim of this study was to compare the spatio-temporal parameters of trained runners and untrained participants with the same foot strike pattern (rearfoot) during running at controlled speeds. Twenty-one participants were classified in two groups according to their training experience: Trained (n=10, amateur runners with long distance training experience) and Untrained (n=11, healthy non-trained participants). Anthropometric variables were recorded, and the participants performed both a submaximal (between 9 and 15 km·h) and a graded exercise running test (from 6 km·h until exhaustion) on a treadmill...
October 6, 2016: Journal of Strength and Conditioning Research
Kelly R Laurson, Pedro F Saint-Maurice, Gregory J Welk, Joey C Eisenmann
The purpose of the study was to describe current levels of musculoskeletal fitness (MSF) in U.S. youth by creating nationally representative age- and sex-specific growth curves for handgrip strength (including relative and allometrically scaled handgrip), modified pull-ups, and the plank test. Participants in the National Youth Fitness Survey (n = 1453) were tested on MSF, aerobic capacity (via submaximal treadmill test), and body composition (body mass index [BMI], waist circumference, and skinfolds). Using LMS regression, age- and sex-specific smoothed percentile curves of MSF were created and existing percentiles were used to assign age- and sex-specific z-scores for aerobic capacity and body composition...
October 6, 2016: Journal of Strength and Conditioning Research
Paul Comfort, Robert Williams, Timothy J Suchomel, Jason P Lake
The aim of this study was to compare load-absorption force-time characteristics of the clean from the knee (CK), power clean from the knee (PCK) and clean pull from the knee (CPK). Ten collegiate athletes (age 27.5 ± 4.2 years; height 180.4 ± 6.7 cm; mass 84.4 ± 7.8 kg), performed three repetitions each of the CK, PCK and CPK with 90% of their 1RM power clean on a force platform. The CK load-absorption duration (0.95 ± 0.35 s) was significantly longer compared to the CPK (0.44 ± 0.15 s; p < 0.001, d = 2...
September 27, 2016: Journal of Strength and Conditioning Research
Erika Zemková
The purpose of this study was to develop an Agility Index (AI), plus related methodology, for representing and quantifying the data variability of agility performance, incorporating varied stimuli number and traveling distances. A group of 84 physically fit subjects performed the agility test. Their task was to touch, with either the left or the right foot, one of four mats according to the location of a stimulus in one of the corners of the screen. Results showed no significant changes in agility time during 60 responses, when subjects traveled a distance of 0...
September 27, 2016: Journal of Strength and Conditioning Research
David Hernando, Nuria Garatachea, Rute Almeida, Jose Antonio Casajús, Raquel Bailón
Heart rate variability (HRV) analysis during exercise is an interesting non-invasive tool to measure the cardiovascular response to the stress of exercise. Wearable heart rate monitors are a comfortable option to measure RR intervals while doing physical activities. It is necessary to evaluate the agreement between HRV parameters derived from the RR series recorded by wearable devices and those derived from an ECG during dynamic exercise of low to high intensity.23 male volunteers performed an exercise stress test on a cycle ergometer...
September 27, 2016: Journal of Strength and Conditioning Research
Hotfiel T, Swoboda B, Krinner S, Grim C, Engelhardt M, Uder M, Hei R
Foam rolling has been developed as a popular intervention in training and rehabilitation. However, evidence on its effects on the cellular and physiological level is lacking. The aim of this study was to assess the effect of foam rolling on arterial blood flow of the lateral thigh. Twenty-one healthy participants (age 25 ± 2 years, height 177 ± 9 cm, body weight 74 ± 9 kg) were recruited from the medical and sports faculty. Arterial tissue perfusion was determined by spectral Doppler and power Doppler ultrasound, represented as peak flow (Vmax), time average velocity maximum (TAMx), time average velocity mean (TAMn), and resistive index (RI), and with semiquantitative grading that was assessed by four blind-folded investigators...
September 23, 2016: Journal of Strength and Conditioning Research
Leo Djaoui, Karim Chamari, Adam Owen, Alexandre Dellal
The aim of the present study was to compare 1) the maximal sprinting speed (MSS) attained by soccer players during matches (MSSmatch) according to their level of play (professional 1st French division vs. elite amateur 4th French division) and the playing positions; and 2) the MSS attained by professional soccer players during 14 different types of small-sided games (SSG, MSSSSG) and match-play. All players monitored through the study performed a 40-m sprint test to assess individual MSS (MSStest) and compare it to the training and match activity, with the calculation of the percentage of MSStest (%MSStest) reached...
September 23, 2016: Journal of Strength and Conditioning Research
Alex S Ribeiro, Brad J Schoenfeld, Steven J Fleck, Fábio L C Pina, Matheus A Nascimento, Edilson S Cyrino
The purpose of the present study was to investigate the effect of resistance training (RT) performed in a pyramid (PR) versus a traditional (TD) system on muscular strength, muscle mass, and hormonal responses in older women. Twenty-five older women (67.6 ± 5.1 years, 65.9 ± 11.1 kg, 154.7 ± 5.8 cm, and 27.5 ± 4.5 kg m) performed both a TD and PR system RT program in a balanced crossover design. The TD program consisted of 3 sets of 8-12 RM with a constant load for the 3 sets, whereas the PR system consisted of 3 sets of 12/10/8 RM with incrementally higher loads for each set...
September 23, 2016: Journal of Strength and Conditioning Research
Mohamed Ali Hammami, Abderraouf Ben Abderrahman, Anthony C Hackney, Wiem Kebsi, Adam L Owen, Amar Nebigh, Ghazi Racil, Zouhair Tabka, Hassane Zouhal
The aim of this study was to investigate the effects of two soccer-training seasons on physical fitness and hormone concentrations in elite youth soccer players. Twenty male elite soccer players (SP, age 14.5 ± 0.4 years) and 20 male control subjects (CS, age 14.3 ± 0.3years) participated to the study. Anthropometric measurements, aerobic (Yo-Yo Intermittent Recovery Test Level 1 (YYIRT1)) and anaerobic soccer relevant performances (jump and sprint tests), blood testosterone (T), cortisol (C),sex hormone binding globulin (SHBG) and T/C ratio were assessed 5 times (from T0 to T4) during two competitive seasons...
September 23, 2016: Journal of Strength and Conditioning Research
M J Landram, A C Utter, C Baldari, L Guidetti, S R McAnulty, S R Collier
The purpose of this study was to compare the hemodynamic, arterial stiffness, and blood flow changes following four weeks of either continuous or discontinuous aerobic exercise in adults. Forty-seven subjects between the ages of 18 and 57 were recruited for one month of either continuous aerobic treadmill work for 30 minutes at 70% max heart rate or 3 bouts of 10 minutes of exercise at 70% of max heart rate with two 10 minute break periods in between, totaling 30 minutes of aerobic work. Following exercise, both CON and DIS groups demonstrated a significant improvement in VO2max (CON 35...
September 23, 2016: Journal of Strength and Conditioning Research
Marcelo R C Dias, Roberto Simao, Francisco J F Saavedra, Nicholas A Ratamess
The purpose of this study was to compare differences in muscle strength and self-selected resistance training intensities between trained subjects who trained under the supervision of a personal trainer (PT) and those who trained without supervision (WoPT). Twenty-one trained subjects, men (n = 12) and women (n = 9), completed three sessions (separated by 48 hours) in the following sequence: (1) self-selected intensity assessment consisting of performance of three sets of 10 repetitions for the leg press, bench press, leg extension, and arm curl exercises with self-selected load; (2) a one repetition-maximum (1RM) test to determine subjects' maximal strength in the four exercises; and (3) a 10 repetition-maximum (10RM) test to determine the maximum load completed for 10 repetitions for each exercise...
September 23, 2016: Journal of Strength and Conditioning Research
John R Harry, Leland A Barker, John A Mercer, Janet S Dufek
There is a wealth of research on impact force characteristics when landing from a jump. However, there are no data on impact forces during landing from a jump with an airborne rotation about the vertical axis. We examined impact force parameters in the vertical and horizontal axes during vertical jump (VJ) landings and vertical jump landings with a 180-degree rotation (VJR). Twenty-four Division 1 male soccer players performed three VJ and VJR landings on a dual-force platform system. Paired-samples t-tests (α=0...
September 22, 2016: Journal of Strength and Conditioning Research
Jon N Radcliffe, Paul Comfort, Tom Fawcett
Research is limited in exploring the specific psychology oriented responsibilities of the strength and conditioning professional. The present research explored the psychological responsibilities adopted by accredited strength and conditioning coaches. Participants comprised 10 participants working within the UK, 3 within the USA and 5 within Australia offering a cross section of experience from raging sport disciplines and educational backgrounds. Participants were interviewed either in person or via Skype...
September 22, 2016: Journal of Strength and Conditioning Research
Timothy J Suchomel, Jason P Lake, Paul Comfort
The purpose of this study was to compare the load absorption force-time characteristics of weightlifting catching and pulling derivatives. Twelve resistance-trained men performed repetitions of the hang power clean (HPC), jump shrug (JS), and hang high pull (HHP) on a force platform with 30, 45, 65, and 80% of their one repetition maximum (1RM) HPC. Load absorption phase duration, mean force, and work were calculated from the force-time data. The HHP produced a significantly longer load absorption phase duration compared to the HPC (p < 0...
September 21, 2016: Journal of Strength and Conditioning Research
Harry G Banyard, Kazunori Nosaka, G Gregory Haff
This study investigated the reliability and validity of the load-velocity relationship to predict the free-weight back squat 1RM. Seventeen strength-trained males performed three 1RM assessments on three separate days. All repetitions were performed to full depth with maximal concentric effort. Predicted 1RMs were calculated by entering the mean concentric velocity of the 1RM (V1RM) into an individualized linear regression equation, which was derived from the load-velocity relationship of three (20, 40, 60% of 1RM), four (20, 40, 60, 80% of 1RM), or five (20, 40, 60, 80, 90% of 1RM) incremental warm-up sets...
September 21, 2016: Journal of Strength and Conditioning Research
Robert McCunn, Matthew Weston, John Ka Hill, Rich D Johnston, Neil V Gibson
The relative age effect is well documented with the maturation-selection hypothesis the most common explanation; however, conflicting evidence exists. We observed the birth-date distribution within an elite junior soccer academy. The influence of physical maturity status on anthropometric variables and sprinting ability was also investigated. Annual fitness testing was conducted over an eight-year period with a total of 306 players (age: 12.5 ± 1.7 y [range: 9.7 - 16.6 y]; stature: 156.9 ± 12.9 cm; mass: 46...
September 21, 2016: Journal of Strength and Conditioning Research
Déborah de Araújo Farias, Jeffrey M Willardson, Gabriel A Paz, Ewertton de S Bezerra, Humberto Miranda
The purpose of this study was to investigate muscle activation, total repetitions and training volume for three bench press exercise modes [Smith machine (SMBP), barbell (BBP), and dumbbell (DBP)] that were followed by a triceps extension (TE) exercise. Nineteen trained men performed three testing protocols in random order, which included: P1) SMBP + TE; P2) BBP + TE; P3) DBP + TE. Each protocol involved four sets with a 10RM load, immediately followed by a triceps extension exercise that was also performed for four sets with a 10RM load...
September 21, 2016: Journal of Strength and Conditioning Research
Francesco Sartor, Silvia Capuzzoni, Gianluca Rospo, Antonio La Torre, Fulvio Vailati, Emanuele Vailati
In gymnastics high levels of executive attention, physical and coordinative capacities are required. However, training planning does not usually account for dynamic alterations in cognitive capacity. This study investigated whether cognitive capacity was altered by the approach of a competition. Ten elite male gymnasts (16 ± 2yrs, 57.3 ± 16.1kg, 1.64 ± 1.27m) were monitored for sleep, life-demands, rating of perceived effort (RPE) and pain, starting 5 days before the competition and up to 5 days after it...
September 21, 2016: Journal of Strength and Conditioning Research
Kristof Kipp, Chad Harris
Lifting greater loads during weightlifting exercises may theoretically be achieved through increasing the magnitudes of net joint impulses or manipulating the joints' effective mechanical advantage (EMA). The purpose of this study was to investigate muscle-specific EMA and joint impulse as well as impulse-momentum characteristics of the lifter-barbell system across a range of external loads during the execution of the clean. Collegiate-level weightlifters performed sub-maximal cleans at 65, 75, and 85% of their 1-repetition maximum (1-RM) while data from a motion analysis system and a force plate were used to calculate lifter-barbell system impulse and velocity, as well as net extensor impulse generated at the hip, knee, and ankle joints and the EMA of the gluteus maximus, hamstrings, quadriceps, and triceps surae muscles...
September 21, 2016: Journal of Strength and Conditioning Research
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