Tai T. Tran

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.

EFFECTS OF SELF-SELECTED MUSIC ON STRENGTH, EXPLOSIVENESS, AND MOOD

Abstract Biagini, MS, Brown, LE, Coburn, JW, Judelson, DA, Statler, TA, Bottaro, M, Tran, TT, and Longo, NA. Effects of self-selected music on strength, explosiveness, and mood. J Strength Cond Res 26(7): 1934–1938, 2012—There has been much investigation into the use of music as an ergogenic aid to facilitate physical performance. However, previous studies have primarily focused on predetermined music and aerobic exercise. The purpose of this study was to investigate the effects of self-selected music (SSM) vs. those of no music (NM) on the mood and performance of the athletes performing bench press and squat jump. Twenty resistance trained collegiate men completed 2 experimental conditions, one while listening to SSM and the other with NM. The subjects reported their profile of mood states (POMS) and rating of perceived exertion (RPE) before and after performing 3 sets to failure of the bench press at 75% 1 repetition maximum (1RM) and 3 reps of the squat jump at 30% 1RM. Statistical analyses revealed no differences in squat jump height or relative ground reaction force, but the takeoff velocity (SSM-2.06 ± 0.17 m·s−1; NM-1.99 ± 0.18 m·s−1), rate of velocity development (SSM-5.92 ± 1.46 m·s−2; NM-5.63 ± 1.70 m·s−2), and rate of force development (SSM-3175.61 ± 1792.37 N·s−1; NM-2519.12 ± 1470.32 N·s−1) were greater with SSM, whereas RPE (SSM-5.71 ± 1.37; NM-6.36 ± 1.61) was greater with NM. Bench press reps to failure and RPE were not different between conditions. The POMS scores of vigor (SSM-20.15 ± 5.58; NM-17.45 ± 5.84), tension (SSM-8.40 ± 3.99; NM-6.07 ± 3.26), and fatigue (SSM-8.65 ± 4.49; NM-7.40 ± 4.38) were greater with SSM. This study demonstrated increased performance during an explosive exercise and an altered mood state when listening to SSM. Therefore, listening to SSM might be beneficial for acute power performance.

Effect of Whole-Body Vibration Warm-Up on Bat Speed in Women Softball Players

Dabbs, NC, Brown, LE, Coburn, JW, Lynn, SK, Biagini, MS, and Tran, TT. Effect of whole-body vibration warm-up on bat speed in women softball players. J Strength Cond Res 24(9): 2296-2299, 2010-Whole-body vibration (WBV) may enhance human performance via augmented muscular strength and motor function if used before performance. Because warm-up is a crucial aspect of preparation for performance, it remains unknown if WBV may enhance bat speed. The purpose of this study was to investigate the effect of WBV warm-up on bat speed. Eleven National Collegiate Athletic Association division I and 11 recreationally trained female softball players volunteered to participate. Subjects randomly performed 3 different warm-up conditions consisting of WBV alone, dry swings alone (DS), and WBV with dry swings (WBVDS). Whole-body vibration was performed on a pivotal vibration platform at a frequency of 25 Hz and an amplitude of 13 mm for one 30-second bout. Thirty seconds after each warm-up condition, 5 maximal bat swings were recorded. There was no significant (p > 0.05) difference between groups by training status, and there was no significant (p > 0.05) difference between WBV (42.39 ± 9.83 mph), DS (40.45 ± 11.00 mph), or WBVDS (37.98 ± 12.40 mph) conditions. These results indicate that WBV warm-up may be used in place of DS to achieve similar bat speeds. Future research should investigate different combinations of WBV warm-up using various frequencies, durations, amplitudes, and rest times.

Relationships Between Lower-Body Muscle Structure and Lower-Body Strength, Power, and Muscle-Tendon Complex Stiffness

Abstract Secomb, JL, Lundgren, LE, Farley, ORL, Tran, TT, Nimphius, S, and Sheppard, JM. Relationships between lower-body muscle structure and lower-body strength, power, and muscle-tendon complex stiffness. J Strength Cond Res 29(8): 2221–2228, 2015—The purpose of this study was to determine whether any relationships were present between lower-body muscle structure and strength and power qualities. Fifteen elite male surfing athletes performed a battery of lower-body strength and power tests, including countermovement jump (CMJ), squat jump (SJ), isometric midthigh pull (IMTP), and had their lower-body muscle structure assessed with ultrasonography. In addition, lower-body muscle-tendon complex (MTC) stiffness and dynamic strength deficit (DSD) ratio were calculated from the CMJ and IMTP. Significant relationships of large to very large strength were observed between the vastus lateralis (VL) thickness of the left (LVL) and right (RVL) leg and peak force (PF) (r = 0.54–0.77, p < 0.01–0.04), peak velocity (PV) (r = 0.66–0.83, p < 0.01), and peak jump height (r = 0.62–0.80, p < 0.01) in the CMJ and SJ, as well as IMTP PF (r = 0.53–0.60, p = 0.02–0.04). Furthermore, large relationships were found between left lateral gastrocnemius (LG) pennation angle and SJ and IMTP PF (r = 0.53, p = 0.04, and r = 0.70, p < 0.01, respectively) and between LG and IMTP relative PF (r = 0.63, p = 0.01). Additionally, large relationships were identified between lower-body MTC stiffness and DSD ratio (r = 0.68, p < 0.01), right (LG) pennation angle (r = 0.51, p = 0.05), CMJ PF (r = 0.60, p = 0.02), and jump height (r = 0.53, p = 0.04). These results indicate that greater VL thickness and increased LG pennation angle are related to improved performance in the CMJ, SJ, and IMTP. Furthermore, these results suggest that lower-body MTC stiffness explains a large amount of variance in determining an athletes ability to rapidly apply force during a dynamic movement.

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.

Analysis of Manoeuvres and Scoring in Competitive Surfing

In competitive surfing, the choice of, and ability to perform different manoeuvres are crucial for the score outcome. Summarised information about manoeuvres, their frequency and scoring could help coaches and athletes to make the right decisions regarding which manoeuvre to choose, if conditions allow, during a competition heat. All waves from the quarter-finals and up during the World Championship Tour 2012 were analysed in regards to performed manoeuvre and score received. Reentries were the most common manoeuvre, but aerial manoeuvre waves and tube rides scored higher with an average wave score of 7.40±1.53 and 6.82±2.13 respectively, compared to other lower risk manoeuvres that scored an average of 5.08±2.21 (p<0.001). Consequently, the high-scoring manoeuvres had lower completion rate (§50-60% as compared to §90%). It was concluded that, high performance surfing athletes should be able to execute risk-taking manoeuvres in addition to having a high completion rate on traditional manoeuvres in competition.

PEAK VERTICAL JUMP POWER ESTIMATIONS IN YOUTHS AND YOUNG ADULTS

Abstract Amonette, WE, Brown, LE, De Witt, JK, Dupler, TL, Tran, TT, Tufano, JJ, and Spiering, BA. Peak vertical jump power estimations in youths and young adults. J Strength Cond Res 26(7): 1749–1755, 2012—The purpose of this study was to develop and validate a regression equation to estimate peak power (PP) using a large sample of athletic youths and young adults. Anthropometric and vertical jump ground reaction forces were collected from 460 male volunteers (age: 12–24 years). Of these 460 volunteers, a stratified random sample of 45 subjects representing 3 different age groups (12–15 years [n = 15], 16–18 years [n = 15], and 19–24 years [n = 15]) was selected as a validation sample. Data from the remaining 415 subjects were used to develop a new equation (“Novel”) to estimate PP using age, body mass (BM), and vertical jump height (VJH) via backward stepwise regression. Independently, age (r = 0.57), BM (r = 0.83), and VJ (r = 0.65) were significantly (p < 0.05) correlated with PP. However, age did not significantly (p = 0.53) contribute to the final prediction equation (Novel): PP (watts) = 63.6 × VJH (centimeters) + 42.7 × BM (kilograms) − 1,846.5 (r = 0.96; standard error of the estimate= 250.7 W). For each age group, there were no differences between actual PP (overall group mean ± SD: 3,244 ± 991 W) and PP estimated using Novel (3,253 ± 1,037 W). Conversely, other previously published equations produced PP estimates that were significantly different than actual PP. The large sample size used in this study (n = 415) likely explains the greater accuracy of the reported Novel equation compared with previously developed equations (n = 17–161). Although this Novel equation can accurately estimate PP values for a group of subjects, between-subject comparisons estimating PP using Novel or any other previously published equations should be interpreted with caution because of large intersubject error (± >600 W) associated with predictions.

Associations Between the Performance of Scoring Manoeuvres and Lower-Body Strength and Power in Elite Surfers

The purpose of this study was to determine whether any significant associations were present between lower-body strength and power, and the performance of turning and aerial manoeuvres in elite surfing athletes. Eighteen competitive male surfers performed a battery of physical tests (countermovement jump (CMJ), squat jump (SJ), and isometric mid-thigh pull (IMTP)) during a single session, in addition to having their performance of turning and aerial manoeuvres ranked from highest to lowest. Significant associations were identified between turning manoeuvre ranking and; peak force in the CMJ, SJ and IMTP (ϱ=−0.737, p<0.01; ϱ=−0.856, p<0.01; ϱ=−0.683, p<0.01, respectively), as well as, peak velocity and jump height in the CMJ (ϱ=−0.560, p=0.02; ϱ=−0.529, p=0.02, respectively). No significant associations were identified between aerial manoeuvre ranking and any strength and power variables. These results suggest that surfing athletes that exhibit greater lower-body isometric and dynamic strength, and power also perform higher scoring turning manoeuvres during wave riding.

Comparison of Physical Capacities Between Nonselected and Selected Elite Male Competitive Surfers for the National Junior Team

PURPOSE To determine whether a previously validated performance-testing protocol for competitive surfers is able to differentiate between Australian elite junior surfers selected (S) to the national team and those not selected (NS). METHODS Thirty-two elite male competitive junior surfers were divided into 2 groups (S=16, NS=16). Their age, height, body mass, sum of 7 skinfolds, and lean-body-mass ratio (mean±SD) were 16.17±1.26 y, 173.40±5.30 cm, 62.35±7.40 kg, 41.74±10.82 mm, 1.54±0.35 for the S athletes and 16.13±1.02 y, 170.56±6.6 cm, 61.46±10.10 kg, 49.25±13.04 mm, 1.31±0.30 for the NS athletes. Power (countermovement jump [CMJ]), strength (isometric midthigh pull), 15-m sprint paddling, and 400-m endurance paddling were measured. RESULTS There were significant (P≤.05) differences between the S and NS athletes for relative vertical-jump peak force (P=.01, d=0.9); CMJ height (P=.01, d=0.9); time to 5-, 10-, and 15-m sprint paddle; sprint paddle peak velocity (P=.03, d=0.8; PV); time to 400 m (P=.04, d=0.7); and endurance paddling velocity (P=.05, d=0.7). CONCLUSIONS All performance variables, particularly CMJ height; time to 5-, 10-, and 15-m sprint paddle; sprint paddle PV; time to 400 m; and endurance paddling velocity, can effectively discriminate between S and NS competitive surfers, and this may be important for athlete profiling and training-program design.