Daniel W. Robbins

Postactivation potentiation and its practical applicability: a brief review.

It has been suggested that postactivation potentiation (PAP) may be manipulated to enhance both acute performance and chronic adaptation. PAP refers to the phenomenon by which acute muscle force output is enhanced as a result of contractile history. Evidence exists regarding the existence of PAP. However, the determination of methods to best manipulate and exploit PAP remains elusive. Studies to date would seem to indicate that the practical applicability of PAP in terms of enhancing athletic performance is limited.

Effect of Loading on Enhancement of Power Performance Over Three Consecutive Trials

The acute effects of maximal voluntary isometric contractions (MVICs) in the squat position on subsequent measures of power output over 3 consecutive sets were investigated. Sixteen trained men experienced with back squats participated in the study. A 7-second MVIC was performed 4 minutes before the execution of 5 maximal countermovement jumps (CMJs) and was repeated for 3 consecutive sets (protocol 1). The results were compared to power output performance in a similar protocol (protocol 2) that excluded the 7-second MVICs. No significant differences occurred in any of the power output measurements between protocol 1 and protocol 2, nor did significance occur linearly across the 4 sets of CMJ, with the exception of a decrease in peak power in protocol 2 (p ≤ 0.05). Using both mean and maximal values only one significant correlation between either relative strength and performance enhancement or absolute strength and performance enhancement was present at p ≤ 0.01. At p ≤ 0.05, significant correlations were found between absolute strength and mean peak power (PP), mean peak acceleration (PA), mean peak force (PF), max PP, max PA, max PF, and max peak velocity. These data indicate that the execution of an MVIC performed before a power exercise was inadequate to acutely enhance power output over any of 3 consecutive trials.

The effect of a complex agonist and antagonist resistance training protocol on volume load, power output, electromyographic responses, and efficiency.

Robbins, DW, Young, WB, Behm, DG, and Payne, WR. The effect of a complex agonist and antagonist resistance training protocol on volume load and power output, electromyographic responses, and efficiency. J Strength Cond Res 24(7): 1782-1789, 2010-The objective of this study was to investigate the acute effects of performing traditional set (TS) vs. complex set (CS) agonist-antagonist training over 3 consecutive sets, on bench press throw (BPT) throw height (TH), peak velocity (PV), peak power (PP), bench pull volume load (VL), and electromyographic (EMG) activity. Eighteen trained men performed 2 testing protocols: TS comprising 3 sets of Bpull followed by 3 sets of BPT performed in approximately 20 minutes or CS comprising 3 sets of both Bpull and BPT performed in an alternating manner in approximately 10 minutes. Throw height, PV, PP, and EMG activity were not different within, or between, the 2 conditions. Bench pull VL decreased significantly from set 1 to sets 2 and 3, under both conditions. Decreases from set 1 to set 2 were 14.55 ± 26.11 and 9.07 ± 13.89% and from set 1 to set 3 were 16.87 ± 29.90 and 14.17 ± 18.37% under CS and TS, respectively. There was no difference in VL per set, or session, between the conditions. Although there was no augmentation of the power measures, CS was determined to have approximately twice the efficiency (ouput/time) as compared to TS. Efficiency calculations for VL, TH, PV, and PP are 103.47 kg·min−1, 26.25 cm·min−1, 1.98 m·s−1·min−1, 890.39 W·min−1 under CS and 54.71 kg·min−1, 13.02 cm·min−1, 0.99 m·s−1·min−1, 459.28 W·min−1 under TS. Comparison of EMG activity between the protocols suggests the level of neuromuscular fatigue did not differ under the 2 conditions. Complex set training would appear to be an effective method of exercise with respect to efficiency and the maintenance of TH, PV, PP, and VL.

The Effect of Training Volume on Lower-Body Strength

Robbins, DW, Marshall, PWM, and McEwen, M. The effect of training volume on lower-body strength. J Strength Cond Res 26(1): 34–39, 2012—The objective of this study was to examine the chronic effects on lower-body strength in resistance trained men of performing varying training volumes over 6 weeks. A pretest and posttest design was used to investigate the effects on 1-repetition maximum (1RM) squat strength. Also, 1RM testing was performed at 3 weeks. Participants were randomly assigned to an intensity-matched (80% of 1RM) low (1-SET), moderate (4-SET), or high (8-SET) volume condition. In addition to significant strength increases in all groups at the end of the 6-week period, increases were observed at 3 weeks under the 4- and 8-SET conditions, which were greater than the improvement under the 1-SET condition. At 6 weeks, the magnitude of improvement was significantly greater for the 8-SET, as compared with that of the 1-SET group. The magnitude of improvement elicited in the 4-SET group was not different from that of the 1-SET or 8-SET groups. The results suggest that “high” volumes (i.e., >4 sets) are associated with enhanced strength development but that “moderate” volumes offer no advantage. Practitioners should be aware that strength development may be dependent on appropriate volume doses and training duration.

Positional relationships between various sprint and jump abilities in elite American football players.

Robbins, DW and Young, WB. Positional relationships between various sprint and jump abilities in elite American football players. J Strength Cond Res 26(2): 388–397, 2012—The purpose of this study was to investigate positional relationships between sprint and jump abilities and body mass in elite college American football players (n = 1,136). Data from the annual National Football League combine over the years 2005–2009 were examined. The measures included for examination were the 9.1-, 18.3-, 36.6-, and flying 18.3-m sprints and the vertical and horizontal jumps. Pearsons correlation coefficients (r) were calculated to determine the relationships between the tests, and coefficients of determination (r2) were used to determine common variance. With the exception of the relationship between the 9.1-m and the flying 18.3-m sprints, the relationships between all sprints are very strong. Vertical jump ability is more strongly associated with maximum speed, as compared with acceleration. Horizontal jump ability is similarly associated with maximum speed and acceleration. The 9.1-, 18.3-, and flying 18.3-m sprints and the jump tests would appear to measure independent skills. Stationary start sprints up to 36.6 m appear to be heavily influenced by acceleration and may thus measure similar characteristics. The flying 18.3-m sprint is recommended as a measure of maximum speed. Body mass was most strongly associated with performance in the lineman group. When body mass was controlled for, correlations weakened across all the groups. The role of body mass remains unclear. Regardless of sport, the present research supports the notion that the relationships between various sprint and jump abilities warrant positional consideration. Coaches and practitioners will be able to use the findings of this research to better test and monitor athletes requiring different skills.

Changes in the athletic profile of elite college American football players.

Abstract Robbins, DW, Goodale, TL, Kuzmits, FE, and Adams, AJ. Changes in the athletic profile of elite college American football players. J Strength Cond Res 27(4): 861–874, 2013—The purpose of this study was to compare positional anthropometric and National Football League (NFL) Combine performance levels in elite college American football players over the 3-year period from 1999 to 2001 to the 3-year period from 2008 to 2010. The sample included 15 offensive and defensive positions, and only those players invited to the combine and subsequently drafted in the same year (n = 1,712) were included in the study. Data from 10 combine physical tests were examined, including weight; height; the 9.1-, 18.3-, and 36.6-m sprints; the vertical and horizontal jumps; the 18.3-m shuttle run; the 3-cone drill; and the 102.1-kg bench press for maximum repetitions. Independent samples t-tests detected differences for each of the 15 positions (p < 0.05). There were no discernible trends in height and weight over the period in question, whereas players in the more recent group significantly improved performance in straight sprinting, the 3-cone drill, and the horizontal jump. Findings suggest that these tests better reflect characteristics such as explosiveness and first-step quickness as compared with the 18.3-m shuttle and the vertical jump, and that such characteristics have become more highly sought after by NFL coaches and scouts. The results of the present research suggest that the position-specific profiles changed over a relatively short period of time. Coaches and practitioners will be able to use the findings of this research to better prepare athletes for entry into the NFL.

Core stability exercises in individuals with and without chronic nonspecific low back pain.

Marshall, PWM, Desai, I, and Robbins, DW. Core stability exercises in individuals with and without chronic nonspecific low back pain. J Strength Cond Res 25(12): 3404–3411, 2011—The aim of this study was to measure trunk muscle activity during several commonly used exercises in individuals with and without low back pain (LBP). Abdominal bracing was investigated as an exercise modification that may increase the acute training stimulus. After an initial familiarization session, 10 patients with LBP and 10 matched controls performed 5 different exercises (quadruped, side bridge, modified push-up, squat, shoulder flexion) with and without abdominal bracing. Trunk muscle activity and lumbar range of motion (LROM) were measured during all exercises. Muscle activity was measured bilaterally during each exercise from rectus abdominis (RA), external obliques (EO), and lumbar erector spinae (ES) with pairs of surface electrodes. Recorded signals were normalized to a percentage of maximal voluntary contractions performed for each muscle. The ES activity was lower for the LBP group during the quadruped (p < 0.05) and higher for RA and EO during the side bridge (p < 0.001), compared to for the healthy controls. Higher muscle activity was observed across exercises in an inconsistent pattern when abdominal bracing was used during exercise. The LROM was no different between groups for any exercise. The lack of worsening of symptoms in the LBP group and similar LROM observed between groups suggest that all exercises investigated in this study are of use in rehabilitating LBP patients. The widespread use of abdominal bracing in clinical practice, whether it be for patients with LBP or healthy individuals, may not be justified unless symptoms of spinal instability are identified.

Physical Performance and Electromyographic Responses to an Acute Bout of Paired Set Strength Training Versus Traditional Strength Training

Robbins, DW, Young, WB, Behm, DG, Payne, WR, and Klimstra, MD. Physical performance and electromyographic responses to an acute bout of paired set strength training versus traditional strength training. J Strength Cond Res 24(5): 1237-1245, 2010-The objective of this study was to investigate the acute effects of performing paired set (PS) vs. traditional set (TS) training over 3 consecutive sets on volume load (VL) and electromyographic (EMG) activity of the pectoralis major, anterior deltoid, latissimus dorsi, and trapezius muscles. Following a familiarization session 16 trained males performed 2 testing protocols using 4 repetition maximum loads: TS (3 sets of bench pull [Bpull] followed by 3 sets of bench press [Bpress] performed in approximately 20 minutes) or PS (3 sets of Bpull and 3 sets of Bpress performed in an alternating manner in approximately 10 minutes). Bpull and Bpress VL decreased significantly from set 1 to set 2 and from set 2 to set 3 under both conditions. There was no difference between VL per set, or over the sessions, between the 2 conditions. PS was determined to be more efficient (VL/time) as compared to TS. EMG activity of the 4 monitored muscles was not different for the 2 conditions or within each condition over the 3 sets. However, there was a significant within-set response in EMG activity in the Bpress exercise. The data suggest that a 4-minute rest interval between sets may not be adequate to maintain VL using either protocol. The data further suggest that PS training may be as effective as TS training in terms of VL maintenance and more effective in terms of efficiency. The comparison of EMG activity between the PS and TS protocols suggests that the level of neuromuscular fatigue does not differ under the 2 conditions. PS training would appear to be an effective method of exercise with respect to VL maintenance and efficiency.

Relationships Between National Football League Combine Performance Measures

Robbins, DW. Relationships between national football league combine performance measures. J Strength Cond Res 26(1): 226–231, 2012—The purpose of this study was to investigate the relationships between the athletic skills measured at the National Football League (NFL) combine. The combine comprises the following tests: 36.6-m sprint with split times at 9.1 and 18.3 m, vertical and horizontal jumps, 18.3-m shuttle run, 3-cone drill, and 102.1-kg bench press. Draftees to the NFL who participated in the annual combine from 2005 to 2009 were included in the study (n = 1,136). Pearsons (r) correlations were calculated to determine the relationships between the tests, and coefficients of determination (r2) were used to determine common variance. The 9.1-, 18.3-, and 36.6-m sprint times are nearly perfectly correlated (r ranges from 0.900 to 0.967) as are the change-of-direction ability tests, 18.3-m shuttle run, and 3-cone drill (r = 0.948), suggesting similar skills are being measured. Performance in both jumping tasks is more strongly associated with longer sprint distances, suggesting mechanisms such as the stretch-shortening cycle may be more important at maximal, or near-maximal, speeds. The correlations between change-of-direction ability and sprinting and jumping are generally much weaker (r ranges from 0.250 to −0.653), suggesting less association and independent motor skills. Although not particularly large correlation coefficients, bench press performance is positively correlated with outcomes in all running drills and inversely correlated with jump abilities, suggesting that in the observed cohort, upper body strength may be of little benefit to these tasks. Incorporation of a nonacceleration influenced (i.e., moving start) measure of maximal speed may be preferred if the intention of a test battery is to measure independent motor skills. Further, when constructing test batteries, either the 18.3-m shuttle or 3-cone drill is likely sufficient as a measure of change-of-direction ability. Test batteries should be constructed to measure independent motor skills.

Positional physical characteristics of players drafted into the National Football League.

Robbins, DW. Positional physical characteristics of players drafted into the national football league. J Strength Cond Res 25(10): 2661–2667, 2011—To investigate the positional physical requirements necessary to be drafted into the National Football League (NFL), data from the annual NFL combine over the years 2005–2009 were examined. Only those players invited to the combine and subsequently drafted in the same year (n = 1,136) were included in the study. Data from 8 combine physical performance tests were examined for 15 positions. Combine measures evaluated for the center, cornerback, defensive end, defensive tackle, free safety, fullback, inside linebacker, offensive guard, offensive tackle, outside linebacker, quarterback, running back, strong safety, tight end, and wide receiver positions were the 9.1-, 18.3-, and 36.6-m sprints, the vertical and broad jumps, the 18.3-m shuttle run, the 3-cone drill, and the 102.1-kg bench press for maximum repetitions and, from this, a predicted measure of 1 repetition maximum. A 1-way analysis of variance detected differences in all 9 performance measures (p < 0.01). Post hoc independent t-tests indicated that over most tests many positions exhibited outcomes significantly different from most other positions. Generally, lineman positions performed inferiorly in sprint, jump and change-of-direction ability measures and superiorly in the upper body strength measures. Conversely, defensive back positions were the worst performers in the upper body strength test, and wide receivers and defensive backs were the best performers in all other measures. In general, offensive and defensive positions that commonly compete directly against one another display similar physical characteristics. Any advantages (statistically significant and not) between positions in direct competition were consistently in favor of defensive positions. The results of the present research present position-specific profiles for each of 15 positions. Coaches and practitioners will be able to use the findings of this research to better prepare athletes for entry into the NFL.