Brandon P. Uribe

A comparison of muscle activation between a Smith machine and free weight bench press

Schick, EE, Coburn, JW, Brown, LE, Judelson, DA, Khamoui, AV, Tran, TT, and Uribe, BP. A comparison of muscle activation between a Smith machine and free weight bench press. J Strength Cond Res 24(3): 779-784, 2010-The bench press exercise exists in multiple forms including the machine and free weight bench press. It is not clear though how each mode differs in its effect on muscle activation. The purpose of this study was to compare muscle activation of the anterior deltoid, medial deltoid, and pectoralis major during a Smith machine and free weight bench press at lower (70% 1 repetition maximum [1RM]) and higher (90% 1RM) intensities. Normalized electromyography amplitude values were used during the concentric phase of the bench press to compare muscle activity between a free weight and Smith machine bench press. Participants were classified as either experienced or inexperienced bench pressers. Two testing sessions were used, each of which entailed either all free weight or all Smith machine testing. In each testing session, each participants 1RM was established followed by 2 repetitions at 70% of 1RM and 2 repetitions at 90% of 1RM. Results indicated greater activation of the medial deltoid on the free weight bench press than on the Smith machine bench press. Also, there was greater muscle activation at the 90% 1RM load than at the 70% 1RM load. The results of this study suggest that strength coaches should consider choosing the free weight bench press over the Smith machine bench press because of its potential for greater upper-body muscular development.

Relationship Between Force-time and Velocity-time Characteristics of Dynamic and Isometric Muscle Actions

Khamoui, AV, Brown, LE, Nguyen, D, Uribe, BP, Coburn, JW, Noffal, GJ, and Tran, T. Relationship between force-time and velocity-time characteristics of dynamic and isometric muscle actions. J Strength Cond Res 25(1): 198-204, 2011-Previous research has investigated the force-time curve characteristics of isometric and dynamic muscle actions; however, few studies have addressed their relationship to dynamic exercise velocity-time variables. The purpose of this study was to investigate relationships between velocity-time characteristics (high pull and vertical jump peak velocity and rate of velocity development [HPPV, HPRVD, VJPV, VJRVD]), force-time characteristics (isometric peak force [IsoPF], body mass adjusted isometric peak force [IsoPF/BM], isometric rate of force development at different millisecond windows [IsoRFD50-250], dynamic peak force [HPPF], body mass adjusted dynamic peak force [HPPF/BM]), and vertical jump height (VJHeight). Nineteen recreationally trained men (age 23.89 ± 2.92 yr; height 176.32 ± 7.06 cm; mass 78.76 ± 16.50 kg) completed 2 testing sessions. The first session consisted of 3 isometric mid-thigh pulls on a force plate with each repetition held for 3 seconds. On the second testing session, subjects completed 3 dynamic mid-thigh high pulls with 30% IsoPF followed by 3 vertical jumps on a force plate. The HPRVD correlated with IsoRFD50 (r = 0.52) and IsoRFD100 (r = 0.49). The HPPV correlated with IsoPF/BM (r = −0.60), IsoRFD50 (r = 0.56), and IsoRFD100 (r = 0.56). The VJHeight correlated with IsoPF/BM (r = 0.61), whereas VJPV correlated with IsoPF/BM (r = 0.62). These correlations suggest that explosive isometric force production within 50 to100 milliseconds may influence the ability to accelerate an implement or body and attain high velocity, albeit in a moderate fashion. In addition, body mass adjusted strength may positively influence vertical jump parameters.

Muscle Activation When Performing the Chest Press and Shoulder Press on a Stable Bench vs. a Swiss Ball

Uribe, BP, Coburn, JW, Brown, LE, Judelson, DA, Khamoui, AV, and Nguyen, D. Muscle activation when performing the chest press and shoulder press on a stable bench vs. a swiss ball. J Strength Cond Res 24(4): 1028-1033, 2010-The aim of this study was to examine the effects of a stable surface (bench) vs. an unstable surface (Swiss ball) on muscle activation when performing the dumbbell chest press and shoulder press. Sixteen healthy men (24.19 ± 2.17 years) performed 1 repetition maximum (1RM) tests for the chest press and shoulder press on a stable surface. A minimum of 48 hours post 1RM, subjects returned to perform 3 consecutive repetitions each of the chest press and shoulder press at 80% 1RM under 4 different randomized conditions (chest press on bench, chest press on Swiss ball, shoulder press on bench, shoulder press on Swiss ball). Electromyography was used to assess muscle activation of the anterior deltoid, pectoralis major, and rectus abdominus. The results revealed no significant difference in muscle activation between surface types for either exercise. This suggests that using an unstable surface neither improves nor impairs muscle activation under the current conditions. Coaches and other practitioners can expect similar muscle activation when using a Swiss ball vs. a bench.

EFFECT OF DELAYED-ONSET MUSCLE SORENESS ON ELBOW FLEXION STRENGTH AND RATE OF VELOCITY DEVELOPMENT

Nguyen, D, Brown, LE, Coburn, JW, Judelson, DA, Eurich, AD, Khamoui, AV, and Uribe, BP. Effect of delayed-onset muscle soreness on elbow flexion strength and rate of velocity development. J Strength Cond Res 23(4): 1282-1286, 2009-Eccentric muscle actions cause muscle damage and lead to delayed-onset muscle soreness (DOMS), which may impair performance. The purpose of this study was to examine the effect of DOMS on elbow flexion strength and rate of velocity development (RVD). Nineteen college male subjects performed 6 tests (pre- and posteccentric and every 24 hours for 4 days). In the preeccentric tests, each subject reported his arm pain and then did 5 concentric repetitions of elbow flexion/extension on an isokinetic dynamometer at 240°·s−1. Each subject then completed 6 sets of 10 eccentric elbow flexion actions at 30°·s−1 and finished with a posteccentric test with another 5 concentric repetitions at 240°·s−1. On days 1-4, each subject reported his arm pain and then did 5 more repetitions at 240°·s−1. Analysis was performed on the values for DOMS, peak torque (PT), and RVD. For DOMS, scores on the posteccentric test (2.34 ± 2.53), day 1 (3.18 ± 2.18), day 2 (3.21 ± 2.91), day 3 (1.81 ± 1.78), and day 4 (1.02 ± 1.30) were all significantly (p < 0.05) greater than the preeccentric scores (0.00 ± 0.00). For PT, the scores on the posteccentric test (22.40 ± 8.87 ft·lb−1) and day 1 (23.88 ± 9.00 ft·lb−1) were both significantly less than on the preeccentric test (29.56 ± 8.42 ft·lb−1). The RVD scores on the posteccentric test (1505.73 ± 462.12 d·s−1·s−1), day 1 (1571.55 ± 475.99 d·s−1·s−1), and day 2 (1546.99 ± 494.52 d·s−1·s−1) were all significantly less than on the preeccentric test (1719.86 ± 473.18 d·s−1·s−1). This suggests that muscle damage may cause significant decreases in elbow flexion concentric strength and RVD even as DOMS remains elevated.

Effect of four different starting stances on sprint time in collegiate volleyball players.

Johnson, TM, Brown, LE, Coburn, JW, Judelson, DA, Khamoui, AV, Tran, TT, and Uribe, BP. Effect of four different starting stances on sprint time in collegiate volleyball players. J Strength Cond Res 24(10): 2641-2646, 2010-Starting stance plays an important role in influencing short-distance sprint speed and, therefore, the ability to reach a ball during sport play. The purpose of this study was to evaluate 4 different starting stances on sprint time. Twenty-six male and female collegiate volleyball players volunteered to participate in 1 testing session. Each subject performed 3 15-ft sprint trials at each of 4 different starting stances (P-parallel, FS-false step, S-staggered, and SFS-staggered false step) in random order. Analysis of variance revealed that there was no significant interaction of sex by stance, but there were main effects for sex (men were faster than women) and stance. The FS (1.18 ± 0.10 seconds), S (1.16 ± 0.07 seconds), and SFS (1.14 ± 0.06 seconds) stances were faster than the P (1.25 ± 0.09 seconds) stance, and the SFS stance was faster than the FS stance. This indicates that starting with a staggered stance (regardless of stepping back) produced the greatest sprinting velocity over the initial 15 feet. Although taking a staggered stance seems counterproductive, the resultant stretch-shortening cycle action and forward body lean likely increase force production of the push-off phase and place the total body center of mass ahead of the contacting foot, thereby, decreasing sprint time.

Performance differences between sexes in the pop-up phase of surfing.

Eurich, AD, Brown, LE, Coburn, JW, Noffal, GJ, Nguyen, D, Khamoui, AV, and Uribe, BP. Performance differences between sexes in the pop-up phase of surfing. J Strength Cond Res 24(10): 2821-2825, 2010-Surfing is a dynamic sport that is multidirectional in nature and requires peak performance in variable ocean conditions. Its growing popularity among the female population has stirred curiosity as to whether women can and will 1 day face their male counterparts in head-to-head competition at the top levels. The purpose of this study was to examine male and female differences in performance of a simulated surfing pop-up movement. Forty recreationally trained surfers (20 men and 20 women) were instructed to lie prone on a force plate, in the pop-up position (similar to a push-up), with only their hands in contact with the plate. A velocity transducer was attached to their back via an adjustable strap around their upper trunk. They completed 3 pop-ups as explosively as possible by pushing forcefully with their hands and jumping to their feet. Absolute and relative force and power were measured. Results demonstrated that men exhibited significantly (p < 0.05) greater relative force (M = 9.56 ± 1.25 N·kg−1, W = 8.15 ± 0.98) and relative power (M = 16.39 ± 4.22 W·kg−1, W = 9.98 ± 2.58) when compared to women. These findings demonstrate that men produce greater force and power than do women even relative to body weight when performing a simulated surfing pop-up movement. It appears that women may be at a disadvantage in regards to peak performance when compared to their male counterparts in the surfing pop-up movement. Therefore, women should train for both maximum and explosive upper-body strength in addition to their time spent surfing.

Effects of different elastic cord assistance levels on vertical jump.

Tran, TT, Brown, LE, Coburn, JW, Lynn, SK, Dabbs, NC, Schick, MK, Schick, EE, Khamoui, AV, Uribe, BP, and Noffal, GJ. Effects of different elastic cord assistance levels on vertical jump. J Strength Cond Res 25(12): 3472–3478, 2011—Currently, little research has been conducted using body weight reduction (BWR) as a means to enhance vertical jump. The purpose of this study was to determine the effects of different elastic cord assistance levels on vertical jump height (JH), takeoff velocity (TOV), relative ground reaction force (rGRF), relative impact force (RIF), and descent velocity (DV). Thirty recreationally trained college men and women (M = 15, W = 15) completed 3 testing sessions consisting of 5 conditions: 0, 10, 20, 30, and 40% BWR. In all BWR conditions, the subjects wore a full body harness while being attached to 2 elastic cords suspended from the ceiling and a linear velocity transducer. They then performed 3 maximal countermovement jumps with arm swing on a force plate. The results indicated no interaction of condition by sex for any variable; however, there was a significant (p < 0.05) main effect for condition for each variable. The JH significantly increased across all conditions (0%: 43.73 ± 1.62 cm, 40%: 64.77 ± 2.36 cm). The TOV at 30% (2.73 ± 0.34 m·s−1) was significantly greater than that at 0% (2.59 ± 0.39 m·s−1) and 10% (2.63 ± 0.34 m·s−1), whereas that at 40% (2.79 ± 0.43 m·s−1) was significantly greater than that at >0, 10, and 20%. The rGRF at 30% (18.62 ± 4.35 N·kg−1) was significantly greater than that at >0, 10, and 20%, whereas that at 40% (21.38 ± 5.21 N·kg−1) was significantly greater than in all conditions. The RIF at 20, 30, and 40% (40%: 61.60 ± 18.53 N·kg−1) was significantly greater than that at 0% (44.46 ± 9.12 N·kg−1). The DV at 20% (2.61 ± 0.31 m·s−1) was significantly greater than at 10%, whereas those at 30 and 40% (2.8 ± 0.41 m·s−1) were significantly greater than at 0, 10, and 20%. These results demonstrate that using different elastic cord levels to reduce body weight appears effective for increasing ascent and descent force and velocity variables. Future research should investigate greater BWR% and chronic training.

Relationship Between Dynamic Kinematics And Isometric Force-Time Characteristics

Previous research has investigated the force-time curve characteristics of isometric muscle actions, however, few have addressed their relationship to the kinematics of dynamic movements. PURPOSE: The purpose of this study was to investigate relationships between dynamic kinematics [high pull peak velocity, high pull rate of velocity development, vertical jump peak velocity (VJPV), vertical jump rate of velocity development (VJRVD)] and isometric force-time curve characteristics [peak force (IsoPF), peak force relative to body mass (IsoPF/BM), rate of force development at various time frames (RFD50ms, RFD100ms, RFD150ms, RFD200ms, RFD250ms, RFDMax)].