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Contreras B.,Auckland University of Technology | Vigotsky A.D.,Arizona State University | Vigotsky A.D.,The New Motion | Schoenfeld B.J.,Lehman College, CUNY | And 3 more authors.
Journal of Applied Biomechanics | Year: 2016

Bridging exercise variations are well researched and commonly employed for both rehabilitation and sport performance. However, resisted bridge exercise variations have not yet been compared in a controlled experimental study. Therefore, the purpose of this study was to compare the differences in upper and lower gluteus maximus, biceps femoris, and vastus lateralis electromyography (EMG) amplitude for the barbell, band, and American hip thrust variations. Thirteen healthy female subjects (age=28.9 y; height=164.3 cm; body mass=58.2 kg) familiar with the hip thrust performed 10 repetitions of their 10-repetition maximum of each variation in a counterbalanced and randomized order. The barbell hip thrust variation elicited statistically greater mean gluteus maximus EMG amplitude than the American and band hip thrusts, and statistically greater peak gluteus maximus EMG amplitude than the band hip thrust (P ≤.05), but no other statistical differences were observed. It is recommended that resisted bridging exercise be prescribed according to the individual's preferences and desired outcomes. © 2016 Human Kinetics, Inc. Source


Beardsley C.,Strength and Conditioning Research Ltd | Contreras B.,Auckland University of Technology
Strength and Conditioning Journal | Year: 2014

Studies support the use of kettlebells for improving power, although evidence for using them to improve strength and aerobic fitness is still equivocal. Studies investigating the biomechanical properties of kettlebell training have been fruitful, and it may be useful for developing sprint running performance and for injury prevention. However, we still do not know the optimal loads for maximizing system and joint power production, how the mechanics, joint moments, and electromyographic activity changes as loads increase during kettlebell swings, nor whether kettlebell training transfers to sports performance. Copyright © 2014 National Strength and Conditioning Association. Source


Beardsley C.,Strength and Conditioning Research Ltd | Contreras B.,Auckland University of Technology
Strength and Conditioning Journal | Year: 2014

HIP EXTENSION MOMENTS INCREASE TO A MUCH GREATER DEGREE THAN KNEE EXTENSION MOMENTS WITH INCREASING LOADS DURING THE SQUAT, LUNGE, AND DEADLIFT EXERCISES AND WITH INCREASING RUNNING SPEEDS, JUMP HEIGHTS, AND LATERAL AGILITY MANEUVERS. THEREFORE, HIP EXTENSION TRAINING SHOULD BE PRIORITIZED IN ATHLETIC CONDITIONING BY (A) USING HIP-DOMINANT EXERCISES IN THE ATHLETE'S PROGRAM, (B) EMPHASIZING HEAVIER LOADS DURING COMPOUND LOWER-BODY RESISTANCE EXERCISES AS THE ATHLETE MATURES, AND (C) INCORPORATING LOADS THAT MAXIMIZE THE HIP EXTENSION MOMENT DURING EXPLOSIVE LOWER-BODY TRAINING. Copyright © National Strength and Conditioning Association. © Lippincott Williams & Wilkins. Source


Vigotsky A.D.,Arizona State University | Vigotsky A.D.,The New Motion | Contreras B.,Auckland University of Technology | Beardsley C.,Strength and Conditioning Research Ltd
PeerJ | Year: 2015

Muscle hypertrophy and atrophy occur frequently as a result of mechanical loading or unloading, with implications for clinical, general, and athletic populations. The effects of muscle hypertrophy and atrophy on force production and joint moments have been previously described. However, there is a paucity of research showing how hypertrophy and atrophy may affect moment arm (MA) lengths. The purpose of this model was to describe the mathematical relationship between the anatomical cross-sectional area (ACSA) of amuscle and its MA length. In the model, the ACSAs of the biceps brachii and brachialis were altered to hypertrophy up to twice their original size and to atrophy to one-half of their original size. The change in MA length was found to be proportional to the arcsine of the square root of the change in ACSA. This change in MA length may be a small but important contributor to strength, especially in sports that require large joint moments at slow joint angular velocities, such as powerlifting. The paradoxical implications of the increase in MA are discussed, as physiological factors influencingmuscle contraction velocity appear to favor a smaller MA length for high velocity movements but a larger muscle MA length for low velocity, high force movements. © 2015 Vigotsky et al. Source


Contreras B.,Auckland University of Technology | Vigotsky A.D.,Arizona State University | Schoenfeld B.J.,Lehman College, CUNY | Beardsley C.,Strength and Conditioning Research Ltd | And 2 more authors.
Journal of Applied Biomechanics | Year: 2016

Front, full, and parallel squats are some of the most popular squat variations. The purpose of this investigation was to compare mean and peak electromyography (EMG) amplitude of the upper gluteus maximus, lower gluteus maximus, biceps femoris, and vastus lateralis of front, full, and parallel squats. Thirteen healthy women (age = 28.9 ± 5.1 y; height = 164 ± 6.3 cm; body mass = 58.2 ± 6.4 kg) performed 10 repetitions of their estimated 10-repetition maximum of each respective variation. There were no statistical (P ≤ .05) differences between full, front, and parallel squats in any of the tested muscles. Given these findings, it can be concluded that the front, full, or parallel squat can be performed for similar EMG amplitudes. However, given the results of previous research, it is recommended that individuals use a full range of motion when squatting, assuming full range can be safely achieved, to promote more favorable training adaptations. Furthermore, despite requiring lighter loads, the front squat may provide a similar training stimulus to the back squat. © 2016 Human Kinetics, Inc. Source

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