Renato Barroso

Effect of eccentric contraction velocity on muscle damage in repeated bouts of elbow flexor exercise.

Eccentric exercise induces muscle damage, but controversy exists concerning the effect of contraction velocity on the magnitude of muscle damage, and little is known about the effect of contraction velocity on the repeated-bout effect. This study examined slow (60 degrees.s(-1)) and fast (180 degrees.s(-1)) velocity eccentric exercises for changes in indirect markers of muscle damage following 3 exercise bouts that were performed every 2 weeks. Fifteen young men were divided into 2 groups based on the velocity of eccentric exercise: 7 in the Ecc60 (60 degrees.s(-1)) group, and 8 in the Ecc180 (180 degrees.s(-1)) group. The exercise consisted of 30 maximal eccentric contractions of the elbow flexors at each velocity, in which the elbow joint was forcibly extended from 60 degrees to 180 degrees (full extension) on an isokinetic dynamometer. Changes in maximal voluntary isometric contraction strength, range of motion, muscle soreness, and plasma creatine kinase activity before and for 4 days after the exercise were compared in the 2 groups using a mixed-model analysis (groupxboutxtime). No significant differences between groups were evident for changes in any variables following exercise bouts; however, the changes were significantly smaller (p<0.05) after the second and third bouts than after the first bout. These results indicate that the contraction velocity does not influence muscle damage or the repeated-bout effect.

Combination of General and Specific Warm-Ups Improves Leg-Press One Repetition Maximum Compared With Specific Warm-Up in Trained Individuals

Abad, CCC, Prado, ML, Ugrinowitsch, C, Tricoli, V, and Barroso, R. Combination of general and specific warm-ups improves leg-press one repetition maximum compared with specific warm-up in trained individuals. J Strength Cond Res 25(8): 2242-2245, 2011—Accurate assessment of muscular strength is critical for exercise prescription and functional evaluation. The warm-up protocol may affect the precision of the 1 repetition maximum (1RM) test. Testing guidelines recommend performing both general and specific warm-ups before strength tests. The general warm-up intends to raise muscle temperature, whereas the specific warm-up aims to increase neuromuscular activation. Although there is scientific evidence for performing the specific warm-up, the effects of general warm-up on strength tests are still unclear. The purpose of this study was to investigate whether the combination of a general with a specific warm-up (G + SWU) protocol would improve leg press 1RM values compared with a specific warm-up (SWU) protocol. Thirteen participants were tested for leg-press 1RM under 2 warm-up conditions. In the first condition, participants performed the SWU only, which was composed of 1 set of 8 repetitions at approximately 50% of the estimated 1RM followed by another set of 3 repetitions at 70% of the estimated 1RM. In the second condition (G + SWU), participants performed the 1RM test after a 20-minute general warm-up on a stationary bicycle at 60% of HRmax and the same specific warm-up as in the SWU. Values of 1RM in SWU and in G + SWU were compared by a paired t-test, and significance level was set at p ≤ 0.05. Strength values were on average 8.4% (p = 0.002) higher in the G + SWU compared with the SWU. These results suggest that the G + SWU induced temperature-dependent neuromuscular adjustments that increased muscle force production capacity. Therefore, these results support the recommendations of the testing guidelines to perform a moderate intensity general warm-up in addition to the specific warm-up before maximum strength assessments.

Maximal Strength, Number of Repetitions, and Total Volume Are Differently Affected by Static-, Ballistic-, and Proprioceptive Neuromuscular Facilitation Stretching

Abstract Barroso, R, Tricoli, V, dos Santos Gil, S, Ugrinowitsch, C, and Roschel, H. Maximal strength, number of repetitions, and total volume are differently affected by static-, ballistic-, and proprioceptive neuromuscular facilitation stretching. J Strength Cond Res 26(9): 2432–2437, 2012—Stretching exercises have been traditionally incorporated into warm-up routines before training sessions and sport events. However, the effects of stretching on maximal strength and strength endurance performance seem to depend on the type of stretching employed. The objective of this study was to compare the effects of static stretching (SS), ballistic stretching (BS), and proprioceptive neuromuscular facilitation (PNF) stretching on maximal strength, number of repetitions at a submaximal load, and total volume (i.e., number of repetitions × external load) in a multiple-set resistance training bout. Twelve strength-trained men (20.4 ± 4.5 years, 67.9 ± 6.3 kg, 173.3 ± 8.5 cm) volunteered to participate in this study. All of the subjects completed 8 experimental sessions. Four experimental sessions were designed to test maximal strength in the leg press (i.e., 1 repetition maximum [1RM]) after each stretching condition (SS, BS, PNF, or no-stretching [NS]). During the other 4 sessions, the number of repetitions performed at 80% 1RM was assessed after each stretching condition. All of the stretching protocols significantly improved the range of motion in the sit-and-reach test when compared with NS. Further, PNF induced greater changes in the sit-and-reach test than BS did (4.7 ± 1.6, 2.9 ± 1.5, and 1.9 ± 1.4 cm for PNF, SS, and BS, respectively). Leg press 1RM values were decreased only after the PNF condition (5.5%, p < 0.001). All the stretching protocols significantly reduced the number of repetitions (SS: 20.8%, p < 0.001; BS: 17.8%, p = 0.01; PNF: 22.7%, p < 0.001) and total volume (SS: 20.4%, p < 0.001; BS: 17.9%, p = 0.01; PNF: 22.4%, p < 0.001) when compared with NS. The results from this study suggest that, to avoid a decrease in both the number of repetitions and total volume, stretching exercises should not be performed before a resistance training session. Additionally, strength-trained individuals may experience reduced maximal dynamic strength after PNF stretching.

The effects of different intensities and durations of the general warm-up on leg press 1RM.

Abstract Barroso, R, Silva-Batista, C, Tricoli, V, Roschel, H, and Ugrinowitsch, C. The effects of different intensities and durations of the general warm-up on leg press 1RM. J Strength Cond Res 27(4): 1009–1013, 2013—The precision of maximum strength assessments (1 repetition maximum; 1RM) is important to evaluate the functional capacity and to prescribe and monitor the training load. Several factors can affect the precision of 1RM tests, including the warm-up procedure. General and specific warm-up routines are recommended to enhance performance. The effects of a specific warm-up have already been acknowledged in improving performance. However, the effects of a general warm-up (GWU) are unclear but seem to depend on its ability to increase muscle temperature while avoiding fatigue. Furthermore, temperature elevation is dependent on both the duration and the intensity of the activity, which may eventually affect 1RM performance. The objective of this study was to investigate the effect of different intensities and durations of GWU on 1RM performance. Sixteen strength-trained men were tested for 1RM leg press after 4 GWU conditions after specific warm-up: short duration and low intensity (SDLI; i.e., 5 minutes at 40% V[Combining Dot Above]O2max), long duration and low intensity (LDLI; i.e., 15 minutes at 40% V[Combining Dot Above]O2max), short duration and moderate intensity (SDMI; i.e., 5 minutes at 70% V[Combining Dot Above]O2max), long duration and moderate intensity (LDMI; i.e., 15 minutes at 70% V[Combining Dot Above]O2max), and the control (CTRL) no-GWU condition. Leg press 1RM values were higher (on average 3%) when subjects performed LDLI (367.8 ± 70.1 kg; p = 0.01), compared with the other 4 conditions. After the LDMI condition, 1RM values were lower (on average −4%) than in the other 4 conditions (345.6 ± 70.5 kg; p = 0.01). There were no differences between SDMI, SDLI, and CTRL (359.4 ± 69.2 kg, 359.1 ± 69.3 kg, and 359.4 ± 70.4 kg, respectively; p = 0.99). According to our results, long-duration low-intensity general warm-up seems be appropriately to improve 1RM performance in strength-trained individuals.

Effects of Strength Training Associated With Whole-Body Vibration Training on Running Economy and Vertical Stiffness

Abstract Roschel, H, Barroso, R, Tricoli, V, Batista, MAB, Acquesta, FM, Serrão, JC, and Ugrinowitsch, C. Effects of strength training associated with whole-body vibration training on running economy and vertical stiffness. J Strength Cond Res 29(8): 2215–2220, 2015—Running economy (RE) is defined as the energy cost to maintain a submaximal running velocity and seems to be affected by individuals neuromuscular characteristics, such as stiffness level. Both resistance training (RT) and whole-body vibration training added to RT (WBV + RT) have been shown to influence those characteristics. Thus, it is conceivable that RT and WBV + RT could also affect RE. The objective of this study was to investigate if a 6-week training period of RT and WBV + RT influences RE and vertical stiffness (VS). Fifteen recreational runners were divided into RT or WBV + RT groups. Running economy, VS, and lower-limb maximum dynamic strength (1 repetition maximum [1RM] half-squat) were assessed before and after the 6-week training period. There was a main time effect for 1RM, but no other statistically significant difference was observed. Neither conventional RT nor RT performed on a WBV platform improved VS and RE in recreational long distance runners. It is possible that movement velocity was rather low, and utilization of stretch-shortening cycle might have been compromised, impairing any expected improvement in RE.

Effects Of Different Combinations Of Strength, Power, And Plyometric Training On The Physical Performance Of Elite Young Soccer Players.

The combination of strength (ST) and plyometric training (PT) has been shown to be effective for improving sport specific performance. However, there is no consensus about the most effective way to combine these methods in the same training session, in order to produce greater improvements in neuromuscular performance of soccer players. Thus, the purpose of this study was to compare the effects of different combinations of ST and PT sequences on strength, jump, speed, and agility capacities of elite young soccer players. Twenty-seven soccer players (age: 18.9±0.6 years) participated in an 8-week resistance training program and were divided into three groups: complex training-CP (ST before PT), traditional training-TD (PT before ST), and contrast training-CT (ST and PT performed alternately, set-by-set). The experimental design took place during the competitive period of the season. The ST was composed of half-squat exercises performed at from 60 to 80% of 1RM; the PT was composed of drop jump exercises executed in a range from 30 to 45 cm. After the experimental period, the maximum dynamic strength (Half-squat 1RM) and vertical jump ability (countermovement jump height) increased similarly and significantly in the CP, TD, and CT (48.6, 46.3, and 53% and 13, 14.2 and 14.7%, respectively). Importantly, whereas the TD group presented a significant decrease in sprinting speed in 10- (7%) and 20-m (6%), the other groups did not show this response. Furthermore, no significant alterations were observed in agility performance in any experimental group. In conclusion, in young soccer players, different combinations/sequences of ST and PT sets result in similar performance improvements in muscle strength and jump ability. However, it is suggested that the use of the CP and CT methods are more indicated to maintain/maximize the sprint performance of these athletes.The combination of strength (ST) and plyometric training (PT) has been shown to be effective for improving sport-specific performance. However, there is no consensus about the most effective way to combine these methods in the same training session to produce greater improvements in neuromuscular performance of soccer players. Thus, the purpose of this study was to compare the effects of different combinations of ST and PT sequences on strength, jump, speed, and agility capacities of elite young soccer players. Twenty-seven soccer players (age: 18.9 ± 0.6 years) participated in an 8-week resistance training program and were divided into 3 groups: complex training (CP) (ST before PT), traditional training (TD) (PT before ST), and contrast training (CT) (ST and PT performed alternately, set by set). The experimental design took place during the competitive period of the season. The ST composed of half-squat exercises performed at 60-80% of 1 repetition maximum (1RM); the PT composed of drop jump exercises executed in a range from 30 to 45 cm. After the experimental period, the maximum dynamic strength (half-squat 1RM) and vertical jump ability (countermovement jump height) increased similarly and significantly in the CP, TD, and CT (48.6, 46.3, and 53% and 13, 14.2, and 14.7%, respectively). Importantly, whereas the TD group presented a significant decrease in sprinting speed in 10 (7%) and 20 m (6%), the other groups did not show this response. Furthermore, no significant alterations were observed in agility performance in any experimental group. In conclusion, in young soccer players, different combinations and sequences of ST and PT sets result in similar performance improvements in muscle strength and jump ability. However, it is suggested that the use of the CP and CT methods is more indicated to maintain/maximize the sprint performance of these athletes.

Blood flow restriction increases metabolic stress but decreases muscle activation during high-load resistance exercise: Blood Flow Restriction Training

Introduction: We investigated differences in metabolic stress (lactate) and muscle activation (electromyography; EMG) when high‐load resistance exercise (HL) is compared with a condition in which blood flow restriction (BFR) is applied during the exercise or during the rest interval. Methods: Twelve participants performed HL with BFR during the intervals (BFR‐I), during the set (BFR‐S), and without BFR. Each condition consisted of 3 sets of 8 repetitions with knee extension at 70% of 1‐repetition maximum. Lactate and root mean square (RMS) from the surface EMG of the vastus lateralis were calculated. Results: Lactate increased in all protocols but was higher with BFR‐I than with BFR‐S and HL. RMS decreased under all conditions, with a larger effect size in BFR‐I (1.47) than in BFR‐S (0.66) and HL (0.59). Discussion: BFR‐I increases lactate, possibly as a result of reduced restoration of ATP. Muscle activation seems to be impacted by mechanical stress but may be reduced by metabolic stress. Muscle Nerve 57: 107–111, 2018

Instability Resistance Training Improves Neuromuscular Outcome in Parkinson's Disease

Purpose This study compared the effects of resistance training (RT) and RT with instability (RTI) on neuromuscular and total training volume (TTV) outcomes obtained as part of the Instability Resistance Training Trial in Parkinsons disease. It also used a linear multiple regression (forward stepwise method) to identify the contribution of neuromuscular outcomes to previously published improvements in the timed-up-and-go test and the Unified Parkinsons Disease Rating Scale, motor subscale score. Methods Thirty-nine patients with moderate to severe Parkinsons disease were randomly assigned to three groups: control (C), RT, and RTI. RT and RTI groups performed resistance exercises twice a week for 12 wk, and only the RTI group used unstable devices to perform resistance exercises. The following neuromuscular outcomes were assessed: quadriceps muscle cross-sectional area, root mean square and mean spike frequency of electromyographic signal, peak torque, rate of torque development, and half relaxation time of the knee extensors and plantarflexors during maximum ballistic voluntary isometric contractions. TTV was calculated for lower limb exercises. Results From pre- to posttraining, RTI improved all of the neuromuscular outcomes (P < 0.05) except half relaxation time of the knee extensors (P = 0.068), despite the lower TTV than RT (P < 0.05). RTI was more effective than RT in increasing the root mean square values of vastus medialis, mean spike frequency of gastrocnemius medialis, and rate of torque development of plantarflexors (P < 0.05). Stepwise regression identified the changes in mean spike frequency of gastrocnemius medialis as the best predictor of improvements in timed-up-and-go test (R2 = 0.58, P = 0.002) and on-medication Unified Parkinsons Disease Rating Scale, motor subscale scores (R2 = 0.40, P = 0.020). Conclusion RTI optimizes neuromuscular adaptations, which partially explains mobility and motor sign improvements in patients with Parkinsons disease.

Effect of hand paddles and parachute on butterfly coordination

Abstract This study investigated the effects of hand paddles, parachute and hand paddles plus parachute on the inter-limb coordination of butterfly swimming. Thirteen male swimmers were evaluated in four random maximal intensity conditions: without equipment, with hand paddles, with parachute and with hand paddles + parachute. Arm and leg stroke phases were identified by 2D video analysis to calculate the total time gap (T1: time between hands’ entry in the water and high break-even point of the first undulation; T2: time between the beginning of the hand’s backward movement and low break-even point of the first undulation; T3: time between the hand’s arrival in a vertical plane to the shoulders and high break-even point of the second undulation; T4: time between the hand’s release from the water and low break-even point of the second undulation). The swimming velocity was reduced and T1, T2 and T3 increased in parachute and hand paddles + parachute. No changes were observed in T4. Total time gap decreased in parachute and hand paddles + parachute. It is concluded that hand paddles do not influence the arm-to-leg coordination in butterfly, while parachute and hand paddles + parachute do change it, providing a greater propulsive continuity.

Effects of resisted sprint training on sprinting ability and change of direction speed in professional soccer players

ABSTRACT Resisted sprint training consists of performing overloaded sprints, which may produce greater effects than traditional sprint training. We compared a resisted sprint training with overload control versus an unresisted sprint training program on performance in soccer players. Eighteen elite athletes were randomly assigned to resisted (RST) or unresisted sprint training protocol (UR). Before and after a 6-week training period, sprinting ability, change of direction speed (COD), vertical jumps (SJ and CMJ), mean power (MP) and mean propulsive power (MPP) at distinct loads were assessed. Both groups improved sprinting ability at all distances evaluated (5m: UR = 8%, RST = 7%; 10m: UR = 5%, RST = 5%; 15m: UR = 4%, RST = 4%; 20m: UR = 3%, RST = 3%; 25m: UR = 2%, RST = 3%;), COD (UR = 6%; RST = 6%), SJ (UR = 15%; RST = 13%) and CMJ (UR = 15%; RST = 15%). Additionally, both groups increased MP and MPP at all loads evaluated. The between-group magnitude-based inference analysis demonstrated comparable improvement (“trivial” effect) in all variables tested. Finally, our findings support the effectiveness of a short-term training program involving squat jump exercise plus sprinting exercises to improve the performance of soccer players.