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The purpose of this study was to compare the gluteus maximus (GM) and hamstring group (HG) electromyographic (EMG) activation levels among selected weight-bearing resistance exercises. Eighteen young adult females with previous resistance training experience completed the study. Strength was assessed on the bilateral squat (BS) (3 repetition maximum [RM]), modified single-leg squat (MSLS) (3RM), and stiff-leg deadlift (SLDL) (8RM) to determine an 8RM load for all lifts. Surface EMG was collected after 48 hours of rest using wireless Trigno IM Sensors using EMMA software (Delsys), which also collected and synchronized 3D hip and knee motion. A maximum voluntary isometric contraction was determined for the GM and HG to normalize the EMG data. During EMG data collection, 3 repetitions were completed using an 8RM load on all 3 exercises. Gluteus maximus EMG was significantly greater than HG EMG on the BS (40.3 vs. 24.4%, p < 0.001), MSLS (65.6 vs. 40.1 %, p < 0.012), and SLDL (40.5 vs. 29.9 %, p < 0.047). The MSLS produced significantly greater HG EMG (p = 0.001) compared with the SLDL, whereas the SLDL was significantly greater (p = 0.004) than the BS. The MSLS GM EMG was also significantly greater (p < 0.001) than the SLDL and BS, whereas no difference was found between the SLDL and BS. Comparing the activation of the 2 muscle groups in all exercises, the GM seems to be the primary muscle recruited whereas the MSLS seems to produce greater GM and HG activation. The data indicate that it would be most beneficial to include the MSLS during GM and HG training. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

TARGETED HIP EXTENSION EXERCISES ARE OFTEN PERFORMED TO DEVELOP STRENGTH, POWER, AND ENDURANCE IN THE HIP EXTENSORS. ALTHOUGH THESE EXERCISES CAN POSSESS SIMILAR MOVEMENT PATTERNS, BIOMECHANICALLY THE INSTANTANEOUS TORQUE AT DIFFERENT RANGES OF HIP EXTENSION VARIES DEPENDING ON BODY POSITION RELATIVE TO SPACE. FOR THESE REASONS, IT IS PROPOSED THAT: (A) HIP EXTENSION EXERCISES MIGHT TRANSFER BETTER TO SPORT ACTIONS WHERE THE REGION OF FORCE ACCENTUATION IS MOST SPECIFIC; (B) HIP EXTENSION EXERCISES MAY LEAD TO UNIQUE STRUCTURAL ADAPTATIONS; AND (C) A VARIETY OF EXERCISES MIGHT BE NECESSARY TO MAXIMIZE HIP EXTENSION STRENGTH AND POWER THROUGHOUT THE ENTIRE RANGE OF MOTION. [ABSTRACT FROM AUTHOR]