Acute Effects of Low vs. High Inertia During Flywheel Deadlifts with Equal Force Impulse on Vertical Jump Performance

BACKGROUND

Flywheel resistance training has gained popularity due to its ability to induce eccentric overload and improve strength and power. This study examined the acute effects of low- (0.025 kg·m2) versus high-inertia (0.10 kg·m2) flywheel deadlifts, matched for force impulse, on the countermovement jump (CMJ) performance, reactive strength index (RSI) during drop jumps (DJs), and rating of perceived exertion (RPE).

METHODS

Sixteen trained participants (twelve men, and four women) performed three conditions in a randomized, counterbalanced order: low-inertia (LOW), high-inertia (HIGH), and control (CTRL). In the LOW and HIGH conditions, we used force plates to measure and equalize the force impulse in the two conditions (HIGH: 20182 ± 2275 N∙s vs. LOW: 20076 ± 2526 N∙s; p > 0.05), by calculating the number of deadlift repetitions required to achieve it (HIGH: 5 repetitions and LOW: 9.8 ± 0.4 repetitions). The RSI and CMJ performance were measured pre-exercise, immediately post-exercise, and at 3, 6, 9, and 12 min post-exercise.

RESULTS

Both the RSI and CMJ performance improved equally after LOW and HIGH flywheel deadlifts compared to baseline and CTRL (p < 0.01). Specifically, the RSI increased from baseline at 3 to 12 min in both conditions (LOW: 12.8 ± 14.9% to 15.4 ± 14.8%, HIGH: 12.1 ± 17.0% to 12.2 ± 11.7%, p < 0.01), while the CMJ increased from 3 to 9 min in LOW (4.3 ± 3.2% to 4.6 ± 4.7%, p < 0.01) and from 6 to 9 min in HIGH (3.8 ± 4.2% to 4.2 ± 4.9%, p < 0.05). No significant differences were observed between LOW and HIGH conditions (p > 0.05), suggesting similar effectiveness of both inertial loads for enhancing performance. The RPE increased similarly after both conditions from baseline to immediately post-conditioning (LOW: from 2.2 ± 1.2 to 5.8 ± 1.4, HIGH: from 1.5 ± 1.0 to 6.1 ± 1.5, p < 0.01) and decreased by the end of the session, although values remained higher than baseline (LOW: 4.1 ± 1.4, p < 0.01, HIGH: 4.5 ± 2.0, p < 0.01).

CONCLUSIONS

These findings highlight the potential of flywheel deadlift exercise as an effective method to potentiate explosive performance of the lower limbs, regardless of inertia, provided that the total force impulse is equal.

Rehabilitation technique of proprioceptive neuromuscular facilitation applied to volleyball vertical jump: A randomized double blinded cross-over clinical trial

OBJECTIVE

compare the acute effect of lower limb stretching exercises with proprioceptive neuromuscular facilitation (PNF) on the antagonist and agonist muscle groups in the execution of a vertical jump (VJ).

METHOD

a randomized, double-blind, crossover clinical trial was conducted involving 30 male volleyball athletes. Group A engaged in PNF on the antagonist muscles, while Group B applied the same method to the agonist muscles. Following a 48-h washout period, the interventions were swapped between the respective groups. Both groups underwent assessments averaging three countermovement vertical jumps (CVJ) with hands on hips and three VJ with arms free. Measurement was taken using the Encoder - Ergonauta I, with over 1500 jumps recorded. The participants were evaluated for their level of flexibility and VJ performance using the Jump Sigma Index application.

RESULTS

an acute decrease in average performance was identified, amounting to 3.86 % for the CMJ with hands on hips and 3.06% for the CVJ with free hands, following PNF in the agonists.

CONCLUSION

there was no statistical difference between the means before and after the intervention when PNF was applied to the antagonistic hamstring muscles. The CVJ modalities with hands on hips and with free hands presented statistically similar indices. The study suggests that there is no impediment to the implementation of warm-up or training protocols that involve stretching in the antagonistic muscles. Further research will be relevant to better clarify the relationship between the effects of stretching on antagonistic muscle groups and to formalize future protocols.

No effects of post-activation performance enhancement in elite male volleyball players under complex training

The aim of this study was to establish reliability of post-activation performance enhancement in three manners: (1) interday morning and afternoon reliability; (2) intraday morning and afternoon reliability; (3) intraday set-to-set reliability. Twelve elite male volleyball players experienced in resistance training performed four identical experimental sessions-two in the morning and two in the afternoon. During each session participants performed a mini complex training session-three sets of a conditioning activity (CA) (3 repetitions of a trap bar deadlift at 80% 1RM with 15% of accommodating resistance) and 90 s after a CA performed squat jump (SJ) with 4 min intra-set rest interval. The ANOVA with repeated measures was used to assess significance of the effect of a CA and ICC to assess reliability of measurements. The PAPE protocol was found to be ineffective to subsequently enhance JH on various occasions. Also, the results of this study suggest that the practitioners may effectively implement appropriately organized complex training as both intraday set-to-set (0.87 and 0.82 for morning sessions; 0.83 and 0.58 for afternoon sessions) and interday morning (0.67) and afternoon (0.8) reliabilities seem to be acceptable. However, introducing two CT sessions within one day is highly questionable as at the moment intraday morning and afternoon reliability is vague (0.88 and 0.48).

Effects of Eccentric Speed during Front Squat Conditioning Activity on Post-activation Performance Enhancement of Hip and Thigh Muscles

The phenomenon of post-activation performance enhancement plays an unidentified role in movement eccentric speed and individual muscle group responses. Therefore, this study aimed to determine whether the loaded front squat (FSq) speed of the eccentric phase would influence the post-activation performance enhancement effect and whether the FSq would elicit similar performance enhancement of knee flexion, knee extension, hip flexion, and hip extension muscles. Twenty resistance-trained handball players performed the FSq under maximum eccentric-concentric speed and 2-s eccentric speed (only the eccentric phase performed), while pre- and post-front squat countermovement jump, knee, and hip isokinetic flexion/extension performance were tested. The FSq conditioning activity was performed in a single set of three repetitions with either 90% (maximum eccentric-concentric speed) or 120% (2-s eccentric speed) of one repetition maximum, and post-performance was measured 4-12 min after the FSq. Athletes randomly changed the FSq eccentric speed and tested the hip or knee isokinetic flexion/extension strength at 180°/s. ANOVA showed that the rate of force development during the jump increased (Cohen d = 0.59-0.77) with no differences between 2-s eccentric and maximum speed eccentric protocols. Isokinetic strength increased after the 2-s eccentric FSq in hip extension (d = 0.76-0.86), knee flexion (d = 0.74-0.88), and hip flexion (d = 0.82), with no differences in knee extension strength. After maximum eccentric-concentric speed, isokinetic strength increased in hip extension (d = 1.25). In conclusion, the FSq conditioning activity enhances hip extensors' performance more than knee extensors' performance. Different eccentric types of muscle action during a conditioning activity alter the level of local muscle enhancement.

The Impact of Range of Motion on Applied Force Characteristics and Electromyographic Activity during Repeated Sets of Bench Press Exercise

This study examined the effects of range of motion (ROM) on applied force, power output and surface electromyographic (sEMG) responses during repeated sets of bench press exercise executed as fast as possible. Ten resistance trained men performed three sets to momentary failure with two-min rest intervals under three different ROM conditions: (a) full ROM (FULL), (b) TOP, at the top half of ROM, and (c) BOTTOM, at the bottom half of ROM. Mean and peak force were higher in TOP compared to FULL and BOTTOM (mean force: 817 ± 80 vs. 657 ± 98 vs. 623 ± 122 N, respectively, p < 0.001) with no differences between FULL and BOTTOM. During repeated sets, large decreases were found in peak (by 29.4 to 45.3%) and mean power (by 55.5 to 64.7%) from the first to the last repetitions. However, the decrease in mean force was only 2% (p < 0.01) and decreases in peak force ranged from 6.7 and 8.8% to zero, indicating the velocity loss was the main contributor to fatigue in power output. Although force and power output in set 3 were unchanged in BOTTOM, mean power output decreased significantly, suggesting that lower performance and fatigue may be related to the longer muscle length. Fatigue was accompanied by an increase in sEMG activity and a decrease in median frequency in all muscles, with triceps brachialis sEMG reflecting more the force and power differences among ROMs. In conclusion, fatigue depends on velocity rather than force loss during bench press exercise at different ROMs.

Accommodating resistance is more effective than free weight resistance to induce post-activation performance enhancement in squat jump performance after a short rest interval

Background/objectives

Prior work regarding post-activation performance enhancement (PAPE) has shown that various resistance training methods and conditioning activities may induce a PAPE effect such as free weight resistance, accommodating resistance or isoinertial resistance. However, the accommodating resistance and other types of resistance have rarely been directly compared. Thus, the aim of this study was to compare the effects of two different conditioning activities (CA) - a trap bar deadlift with (FW + AR condition) or without (FW condition) accommodating resistance - on subsequent squat jump (SJ) performance after a short rest interval of 90s.

Methods

The study had a cross-over design and fifteen strength trained males (mean age: 22.9 ± 2.1 years; mean relative strength level 2.01 ± 0.27 kg/body mass) participated in one familiarization, two experimental and one control session (CNTR condition). Two CAs were implemented throughout the study - a single set of 3 repetitions of a trap bar deadlift at 80 % of 1RM using solely free weight resistance or with the addition of approximately 15 % of 1RM elastic band tension. The SJ measurements were performed at the baseline and 90s after CAs.

Results

The FW + AR condition significantly improved subsequent SJ performance (p < 0.05, effect size 0.34) whereas the FW and CNTR conditions were found to be ineffective to acutely enhance performance.

Conclusions

Our results suggest that the addition of accommodating resistance is superior to free weight resistance in order to acutely improve jump performance after a 90s rest interval. To observe the performance enhancement effect with solely free weight resistance it should be considered to introduce alteration in loading strategies or possibly lengthening the rest interval.

Acute Effects of Supra- and High-Loaded Front Squats on Mechanical Properties of Lower-Limb Muscles

Knowledge about the acute effects of supramaximal-loaded resistance exercises on muscle mechanical properties is scarce. Therefore, this study aimed to examine changes in dominant limb biceps femoris and vastus lateralis oscillation frequency and stiffness before and after high- and supramaximal-loaded front squats. Nineteen male handball players participated in the experimental session with a barbell front squat 1RM. The first set was performed at 70% of the 1RM for four repetitions, and the second and third sets were performed at 90%1RM in an eccentric-concentric or an eccentric-only manner at 120% of the 1RM for three repetitions. The handheld myometer was used for the measurement of the biceps femoris and vastus lateralis stiffness and the oscillation frequency of the dominant limb 5 min before and at the 5th and 10th min after front squats. A two-way ANOVA neither indicated a statistically significant interaction (p = 0.335; η2 = 0.059 and p = 0.103; η2 = 0.118), the main effect of a condition (p = 0.124; η2 = 0.126 and p = 0.197; η2 = 0.091), nor the main effect of the time point (p = 0.314; η2 = 0.06 and p = 0.196; η2 = 0.089) for vastus lateralis and biceps femoris stiffness. However, there was a statistically significant interaction (F = 3.516; p = 0.04; η2 = 0.163) for vastus lateralis oscillation frequency. The post hoc analysis showed a significantly higher vastus lateralis oscillation frequency at POST (p = 0.037; d = 0.29) and POST_10 (p = 0.02; d = 0.29) compared to PRE during the SUPRA condition. Moreover, Friedman's test indicated statistically significant differences in biceps femoris oscillation frequency (test = 15.482; p = 0.008; Kendall's W = 0.163). Pairwise comparison showed a significantly lower biceps femoris oscillation frequency in POST (p = 0.042; d = 0.31) and POST_10 (p = 0.015; d = 0.2) during the HIGH condition compared to that in the corresponding time points during the SUPRA condition. The results of this study indicate that the SUPRA front squats, compared to the high-loaded ones, cause a significant increase in biceps femoris and vastus lateralis oscillation frequency.

Effects of peripheral electromagnetic stimulation after an eccentric exercise-induced delayed-onset muscle soreness protocol in professional soccer players: a randomized controlled trial

Introduction: To examine the effects of peripheral electromagnetic stimulation in male professional soccer players on markers of Delayed Onset Muscular Soreness (DOMS), induced by a protocol of exercise (60 min of eccentric and plyometric). Methods: A randomized controlled trial with fourty-five professional soccer players aged 22.33 ± 4.82 years participated in the study. Twenty-three participants were assigned to the experimental group with peripheral electromagnetic stimulation (5 stimulations of 5 s at 100 HZ with 55 s of rest for a total of 5 min of treatment) and the remaining 22 participants were assigned to the control group. Pain pressure threshold (PPT) of the vastus medialis, the Visual Analogue Scale-Fatigue (VAS-F), half squat (HS) test and the maximum voluntary contraction of the quadriceps were assessed. All evaluations were performed before and after 1 h of the eccentric exercise induced DOMS, as well as at post 24-48, and 72 h. Results: Group-by-time interaction was observed in PPT of the vastus medialis (p = 0.040) with a medium effect size (η² p = 0.069). From 48 to 72 h the experimental group showed an increase of PPT compared to control group (p = 0.015). There was no group-by-time interaction for HS, quadriceps strength and VAS-F (p > 0.05). Discussion: Peripheral electromagnetic stimulation in male professional soccer players did not produce significant improvements in the power and strength of the lower limbs but decreased the peripheral sensitization of the vastus medialis after eccentric exercise protocol. Clinical Trial Registration: https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=384050&isReview=true, Identifier: ACTRN12622000841774.

Acute Effects of Isometric Conditioning Activity on the Viscoelastic Properties of Muscles and Sprint and Jumping Performance in Handball Players

ABSTRACT

Krzysztofik, M, Spieszny, M, Trybulski, R, Wilk, M, Pisz, A, Kolinger, D, Filip-Stachnik, A, and Stastny, P. Acute effects of isometric conditioning activity on the viscoelastic properties of muscles and sprint and jumping performance in handball players. J Strength Cond Res 37(7): 1486-1494, 2023-The effects of conditioning activity (CA) on muscle stiffness are currently unknown, suggesting that maximum CA effort can increase or decrease the stiffness of involved muscle groups. Therefore, this study aimed to investigate the effect of maximal isometric half-squats on the viscoelastic properties of muscles and postactivation performance enhancement (PAPE) in sprints and jumps. Twelve handball players underwent a standard warm-up and baseline assessment of muscle stiffness and tone of vastus lateralis and gastrocnemius medialis muscle, followed by 20-m sprint with intermediate measures at 5 and 10 m and countermovement jump. The PAPE was assessed by repeating the tests (at 4th, 8th, and 12th minute post-CA) after a CA protocol consisting of 3 sets of 3-second maximal isometric half-squats (EXP) or a control condition (CTRL) without any CA. The vastus lateralis stiffness in the 4th and 12th minute and muscle tone in the 4th minute post-CA significantly decreased compared with baseline ( p = 0.041, ES = 0.57; p = 0.013, ES = 0.52; p = 0.004, ES = 0.81, respectively) in the EXP condition. The 20-m sprint time significantly decreased at all post-CA time points compared with the baseline for the EXP condition ( p < 0.033) and the after values in the CTRL condition ( p < 0.036). In comparison to baseline, the 10-m sprint time decreased in the eighth minute post-CA ( p = 0.021; ES = 0.82) in the EXP condition. Moreover, it was significantly lower at the 8th and 12th minute post-CA ( p = 0.038; ES = 0.71 and p = 0.005; ES = 1.26) compared with that time points in the CTRL condition. The maximal isometric half-squats effectively improved sprint performance and significantly decreased vastus lateralis tone and stiffness. These findings offer new insights into the assessment of viscoelastic properties for evaluating the fatigue or potentiation state, which requires further investigation.

Acute Effects of Complex Conditioning Activities on Athletic Performance and Achilles Tendon Stiffness in Male Basketball Players

The goal of this study was to compare the effects of a bilateral conditioning activity consisting of back squats and drop jumps with a unilateral one consisting of split squats and depth jumps to lateral hop over sequentially performed countermovement jump (CMJ), modified t-agility test (MAT), and Achilles tendon stiffness. Twenty-six basketball players participated in this study and were randomly and equally assigned to one of two different test groups: bilateral (B - CA) or unilateral (U - CA) conditioning activity group. The B - CA group completed 2 sets of 4 repetitions of back squats at 80% of one-repetition maximum (1RM), then 10 drop jumps, while the U - CA group performed 2 sets of 2 repetitions of split squats on each leg at 80%1RM, followed by 5 depth jumps to lateral hop on each leg as conditioning activity (CA) complexes. After a warm-up and 5 min before the CA the baseline Achilles tendon stiffness, CMJ, and MAT time measurement were performed. In the 6th min after the CA, all tests were re-tested in the same order. The two-way repeated measures mixed ANOVAs revealed that both B - CA and U - CA failed to produce significant improvements in CMJ and MAT performance. In addition, a significant increase in Achilles stiffness was demonstrated with both protocols (a main effect of time: p = 0.017; effect size = 0.47; medium). This study revealed that combining back squats and drop jumps, as well as split squats and depth jumps to a lateral hop, had no effect on subsequent CMJ and MAT performance in basketball players. Based on these results, it can be assumed that combinations of exercises, even if they have similar movement patterns, may cause excessive fatigue, resulting in no PAPE effect.

Post-activation effects of accommodating resistance and different rest intervals on vertical jump performance in strength trained males

BACKGROUND

Post-activation potentiation performance (PAPE) is a physiological phenomenon that has been studied numerously but the researchers are still seeking for the optimal application methods. The accommodating resistance was found to be an effective training method to acutely enhance subsequent explosive performance. The purpose of this study was to evaluate the effects of performing a trap bar deadlift with accommodating resistance on squat jump (SJ) performance with different rest intervals (90, 120, 150s).

METHODS

The study had a cross-over design and fifteen strength-trained males (age 22.9 ± 2.1 years; body height 182 ± 6.5 cm; body mass: 80.4 ± 9.8 kg; body fat 15.8 ± 7.0%; BMI 24.1 ± 2.8; lean body mass 67.5 ± 8.8 kg) participated in one familiarization, three experimental and three control sessions within three weeks. The conditioning activity (CA) used in the study was a single set of 3 repetitions of a trap bar deadlift at 80% 1RM with approximately 15% 1RM of an elastic band. The SJ measurements were performed at the baseline and post-CA after 90 or 120 or 150s.

RESULTS

The 90s experimental protocol significantly improved (p < 0.05, effect size 0.34) acute SJ performance whereas 120 and 150 s experimental protocols did not significantly improve performance. The following tendency was observed - the longer the rest interval, the smaller the potentiation effect; p value for 90s (0.046), 120s (0.166), 150s (0.745).

CONCLUSIONS

A trap bar deadlift with accommodating resistance and 90s rest interval can be used to acutely enhance jump performance. A 90s rest interval was found to be optimal to enhance subsequent SJ performance, but the potential rest interval extension to 120s could also be taken by strength and conditioning coaches as the PAPE effect is highly individual. However, exceeding the rest interval to more than 120s may not be effective in optimising the PAPE effect.

The sex effects on changes in jump performance following an isometric back squat conditioning activity in trained adults

There are limited data concerning the disparity between males and females in post-activation performance enhancement (PAPE) based on isometry. Therefore, this study aimed to establish if sex differences exist in the PAPE effect on jump height. The study included 30 males and 15 females aged between 19 and 25, with relative strength in the back squat of at least 110% of body weight and a minimum of 3 years of resistance training experience. A baseline countermovement jump (CMJ) was performed, and the PAPE protocol, which involved three 4-s sets of isometric full-back squats with a 1-min rest interval, was introduced. Five CMJs were performed over the following 9 minutes in 2 minutes rest intervals. Changes (Δ) towards the baseline and each jump height results were calculated and analyzed in the absolute (cm) and relative (%) approach. The repeated measures ANOVA with sex as between-groups effect and time of the changes as within-group effect were conducted. Results showed statistically significant interaction (sex×time) in absolute changes (Δ cm) (F = 2.50, η2 = 0.05, p = 0.0447), which indicated that the sex effect has changed over time. Post-hoc test showed that during the first 3 minutes, men and women benefited equally, but in the fifth and seventh minutes, the observed changes were greater in men, thus close to significance (p = 0.0797, p = 0.0786), and in the last minute, the difference was statistically significant (p = 0.0309). Also, a statistically significant interaction effect was observed for relative changes (Δ %) (F = 4.22, η2 = 0.09, p = 0.0027). At the beginning (the first and third minutes), changes in females were greater than in males, but the differences were insignificant. However, after 5 minutes, the decrease in females was observed with statistically significant differences in the last minute compared to males (p = 0.0391). Chi-Squared analysis indicated that the time to peak performance was insignificant (χ 2 = 7.45, p = 0.1140) in both sexes. The introduced PAPE protocol based on isometry improved jump height in both sexes, with performance enhancement recorded in the third-minute post-activation. However, performance decreased in females over the next 6 minutes, while it was maintained in the male group. Despite the generally positive short-term effects of the protocol on females, the usefulness of the protocol is limited.

Intermittent Voluntary Isometric Contractions Effects on Performance Enhancement and Sticking Region Kinematics in the Bench Press

During the last years, post-activation performance enhancement (PAPE) has gained notorious popularity due to the capacity to improve the acute rate of force development (RFD) using different strategies with different muscle contraction regimes as conditioning stimuli. The aim of the present study was to analyse the role of a maximal isometric post-activation performance enhancement (PAPE) protocol in performance and its effects on the kinematics of the sticking region. Twenty-one trained participants (age 26.4 ± 5.4 years) underwent two experimental sessions: an experimental session consisting of a single set and a single repetition of the bench press at the 93% of 1RM (which is considered a traditional conditioning activity to induce PAPE) (TRAD) and an isometric experimental session (ISO) consisting of 15 maximal voluntary isometric contractions in the sticking region of the medium grip bench press lasting 1 s with a 1 s rest interval between contractions. Both TRAD and ISO experimental conditions improved performance from post0 to post4, post8, post12 and post16, but only the ISO condition improved performance from the start of the lift to the start of the sticking region from pre to post (p < 0.001), and only the ISO condition improved maximum (p = 0.005) and minimum (p = 0.025) peak velocities. The results of this study suggest that short duration maximal voluntary isometric contractions improve the velocity of the lift prior to the initiation of the sticking region, which ultimately improves the impulse and facilitates the lift.

Time Duration of Post-Activation Performance Enhancement (PAPE) in Elite Male Sprinters with Different Strength Levels

(1) Purpose: This study aimed to explore the time duration of post-activation performance enhancement (PAPE) in elite male sprinters with different strength levels. (2) Methods: Thirteen elite male sprinters were divided into a strong group (relative strength: 1RM squat normalized by body mass of ≥2.5; n = 6) and a weak group (relative strength of <2.5; n = 7). All sprinters performed one static squat jump (SSJ) at baseline and 15 s, 3 min, 6 min, 9 min, and 12 min following an exercise protocol including three reps of a 90% 1RM back squat. Two force plates were used to determine the vertical jump height, the impulse output, and the power output for all SSJs. (3) Results: Significant improvements in vertical jump height and peak impulse were observed (p < 0.05) at 3, 6, and 9 min, without significant between-group differences. The peak power had a significant increase in 3 min (p < 0.01) and 6 min (p < 0.05), with also no significant difference between-group differences. Moreover, the stronger subjects induced a greater PAPE effect than the weaker counterparts at 3, 6, and 9 min after the intervention. The maximal benefit following the intervention occurred at 6 min and 3 min after the intervention in the stronger and weaker subjects, respectively. (4) Conclusions: The findings indicated that three reps of a 90% 1RM back squat augmented the subsequent explosive movement (SSJ) for 3−9 min in elite male sprinters, especially in stronger sprinters.

Effectiveness of either short-duration ischemic pre-conditioning, single-set high-resistance exercise, or their combination in potentiating bench press exercise performance

This study compared the effects of short-duration ischemic preconditioning, a single-set high-resistance exercise and their combination on subsequent bench press performance. Twelve men (age: 25.8 ± 6.0 years, bench press 1-RM: 1.21 ± 0.17 kg kg^-1 body mass) performed four 12 s sets as fast as possible, with 2 min of recovery between sets, against 60% 1-RM, after: a) 5 min ischemic preconditioning (IPC; at 100% of full arterial occlusion pressure), b) one set of three bench press repetitions at 90% 1-RM (PAPE), c) their combination (PAPE + IPC) or d) control (CTRL). Mean barbell velocity in ischemic preconditioning was higher than CTRL (by 6.6-9.0%, p < 0.05) from set 1 to set 3, and higher than PAPE in set 1 (by 4.4%, p < 0.05). Mean barbell velocity in PAPE was higher than CTRL from set 2 to set 4 (by 6.7-8.9%, p < 0.05), while mean barbell velocity in PAPE + IPC was higher than CTRL only in set 1 (+5.8 ± 10.0%). Peak barbell velocity in ischemic preconditioning and PAPE was higher than CTRL (by 7.8% and 8.5%, respectively; p < 0.05). Total number of repetitions was similarly increased in all experimental conditions compared with CTRL (by 7.0-7.9%, p < 0.05). Rating of perceived exertion was lower in ischemic preconditioning compared with CTRL (p < 0.001) and PAPE (p = 0.045), respectively. These results highlight the effectiveness of short-duration ischemic preconditioning in increasing bench press performance, and suggest that it may be readily used by strength and conditioning coaches during resistance training due to its brevity and lower perceived exertion.

Effects of Unilateral Conditioning Activity on Acute Performance Enhancement: A Systematic Review

This review aimed to summarize the reported effects of unilateral conditioning activity (CA) on unilateral performance, bilateral performance, and the contribution of activated body limb to bilateral performance. A systematic search on MEDLINE, SPORTDiscus, Scopus, and Google Scholar was conducted on February 2022. Twenty-three studies met the inclusion criteria. Throwing, jumping, swimming, change of direction, and isokinetic performance were used as outcome measures to assess the impact of unilateral CAs on inducing post-activation performance enhancement. Eleven studies examined the effectiveness of resistance exercises as a CA, seven investigated plyometric exercises, and five used isokinetic muscle actions as CAs. Notably, only three studies directly compared the effects of bilateral and unilateral CA, and no study reported possible changes in the contribution of each limb during bilateral exercises executed following unilateral CA. Split squats were the most often studied CA (7), and it was shown that multiple sets of high-loaded split squats (85% one-repetition maximum) executed as CA, improve vertical jumping and change of direction after 4 to 8 min of recovery. At the same time, multiple sets of alternate leg bounds performed with ~10% body weight or without any external load result in an improvement of sprint performance, 2 and 8 min later, with the effect being greater when loaded jumps are used. The unilateral CAs such as split squats, alternate leg bounds, and drop jumps can be effectively used to acutely improve a wide variety of athletic tasks, including jumping, sprinting, change of direction, and swimming performance.

Acute effects of combined isometric and plyometric conditioning activities on sports performance and tendon stiffness in female volleyball players

This study aimed to compare the effects of bilateral and unilateral conditioning activities (CA; combined isometric and plyometric) on countermovement jump performance, modified t-agility test, Achilles tendon stiffness and skin surface temperature. Thirteen female semi-professional volleyball players performed two CAs in random order: 1) bilateral isometric half back squats followed by bilateral drop jumps (BI-CA); and 2) unilateral isometric half back squats followed by unilateral drop jumps (UNI-CA). To assess the effects of CAs, countermovement jump, modified t-agility test, Achilles tendon stiffness and skin surface temperature measurements were performed 5 min before and 6 min after the CA. Both CAs significantly increased thigh skin surface temperature from pre- to post-CA (BI-CA, p < 0.001; effect size [ES] = 1.41 and UNI-CA, p = 0.001; ES = 1.39) but none of them influenced modified t-agility test time (interaction: p = 0.338, main effect of time: p = 0.121 and condition: p = 0.819). The countermovement jump height and modified reactive strength index significantly increased from pre-to post-CA during the BI-CA condition (p = 0.003, ES = 0.45, and p = 0.008, ES = 0.48) but not for UNI-CA (p = 0.061, ES = 0.18 and p = 0.065, ES = 0.26). No significant impact has been found for countermovement depth (interaction: p = 0.054, main effect of time: 0.097, and condition: p = 0.41) as well as for contraction time (interaction: p = 0.536, main effect of time: p = 0.224, and condition: p = 0.807). Moreover, stronger and weaker limb CMJ relative peak force significantly decreased from pre-to post-CA (p = 0.014, ES = −0.31, and p = 0.027, ES = −0.26; respectively) during UNI-CA condition but not for BI-CA (p = 0.096, ES = 0.23, and p = 1.41, ES = 0.18). The stronger and weaker limb Achilles tendon stiffness significantly increased from pre-to post-CA during the UNI-CA condition (p = 0.013, ES = 0.60 and p < 0.001, ES = 0.79; respectively) but not for BI-CA (p = 0.66; ES = 0.15 and p = 0.265; ES = 0.42). Furthermore, the post-CA stronger limb Achilles tendon stiffness during the UNI-CA was significantly higher than that noted during the BI-CA (p = 0.006, ES = 0.7). The present study showed that combined isometric and plyometric bilateral CA effectively improved the countermovement jump but did not enhance the t-agility test performance. These findings indicate that exercise combinations could effectively produce a post-activation performance enhancement effect but should replicate the following explosive task as much as possible.

Post-Isometric Back Squat Performance Enhancement of Squat and Countermovement Jump

The effectiveness of isometric conditioning activity (CA) is not well described in terms of the level of performance enhancement and the presence of a stretch and shortening cycle in subsequent explosive tasks. Therefore, the aim of this study was to evaluate the effect of a maximum isometric squat as the CA and a subsequent squat jump (SJ) and countermovement jump (CMJ) height. A total of 31 semi-professional handball and soccer players were randomly assigned to two different conditions: (i) 3 sets of 3 repetitions (each lasting 3 s) of maximum isometric back squats (EXP), and (ii) no CA (CTRL). The jump height measurements were performed 5 min before the CA and approximately at the 4th and 8th minute following the completion of the CA. Due to the high inter-individual variability in the potentiation responses, the best value obtained post-CA was also analyzed. The SJ height significantly increased from baseline to the 8th minute post-CA (p = 0.004; ES = 0.31; Δ = +3.1 ± 5.0%) in the EXP condition. On the other hand, the CMJ height was significantly higher in the 4th (p = 0.001; ES = 0.23; Δ = +2.7 ± 3.7%) and 8th minute post-CA (p = 0.005; ES = 0.32; Δ = +3.6 ± 5.7%) in comparison to baseline during the EXP condition. Furthermore, SJ height significantly increased from baseline to the best time-point during the EXP (p < 0.001; ES = 0.47; Δ = +4.9 ± 4.9%) and CTRL (p = 0.038; ES = 0.21; Δ = +2.5 ± 5.8%) condition. Moreover, the CMJ height was significantly higher at the best time-points than at the baseline during EXP (p < 0.001; ES = 0.53; Δ = +5.6 ± 4.7%) and CTRL (p = 0.002; ES = 0.38; Δ = +3.1 ± 5.2%) condition. The findings from this study indicate that a maximum isometric squat, used as a CA, effectively improved SJ and CMJ height. This suggests that the presence or absence of a stretch and shortening cycle in both CA and post-CA tasks does not significantly impact the post-activation performance enhancement response.

Changes in Body Composition and Strength after 12 Weeks of High-Intensity Functional Training with Two Different Loads in Physically Active Men and Women: A Randomized Controlled Study

This study examined the effects of two different resistance loads during high-intensity Functional Training (HIFT) on body composition and maximal strength. Thirty-one healthy young individuals were randomly assigned into three groups: moderate load (ML: 70% 1-RM), low load-(LL: 30% 1-RM), and control (CON). Each experimental group performed HIFT three times per week for 12 weeks with a similar total volume load. Body fat decreased equally in both experimental groups after 6 weeks of training (p < 0.001), but at the end of training it further decreased only in LL compared to ML (−3.19 ± 1.59 vs. −1.64 ± 1.44 kg, p < 0.001), with no change in CON (0.29 ± 1.08 kg, p = 0.998). Lean body mass (LBM) increased after 6 weeks of training (p = 0.019) in ML only, while after 12 weeks a similar increase was observed in LL and ML (1.11 ± 0.65 vs. ML: 1.25 ± 1.59 kg, p = 0.034 and 0.013, respectively), with no change in CON (0.34 ± 0.67 kg, p = 0.991). Maximal strength increased similarly in four out of five exercises for both experimental groups by between 9.5% and 16.9% (p < 0.01) at the end of training, with no change in CON (−0.6 to 4.9%, p > 0.465). In conclusion, twelve weeks of HIFT training with either low or moderate resistance and equal volume load resulted in an equal increase in LBM and maximal strength, but different fat loss.

Enhancement of Countermovement Jump Performance Using a Heavy Load with Velocity-Loss Repetition Control in Female Volleyball Players

Although velocity control in resistance training is widely studied, its utilization in eliciting post-activation performance enhancement (PAPE) responses receives little attention. Therefore, this study aimed to evaluate the effectiveness of heavy-loaded barbell squats (BS) with velocity loss control conditioning activity (CA) on PAPE in subsequent countermovement jump (CMJ) performance. Sixteen resistance-trained female volleyball players participated in this study (age: 24 ± 5 yrs.; body mass: 63.5 ± 5.2 kg; height: 170 ± 6 cm; relative BS one-repetition maximum (1RM): 1.45 ± 0.19 kg/body mass). Each participant performed two different conditions: a set of the BS at 80% 1 RM with repetitions performed until a mean velocity loss of 10% as the CA or a control condition without CA (CNTRL). To assess changes in jump height (JH) and relative mean power output (MP), the CMJ was performed 5 min before and throughout the 10 min after the CA. The two-way analysis of variance with repeated measures showed a significant main effect of condition (p = 0.008; η² = 0.387) and time (p < 0.0001; η² = 0.257) for JH. The post hoc test showed a significant decrease in the 10th min in comparison to the value from baseline (p < 0.006) for the CNTRL condition. For the MP, a significant interaction (p = 0.045; η² = 0.138) was found. The post hoc test showed a significant decrease in the 10th min in comparison to the values from baseline (p < 0.006) for the CNTRL condition. No significant differences were found between all of the time points and the baseline value for the CA condition. The CA used in the current study fails to enhance subsequent countermovement jump performance in female volleyball players. However, the individual analysis showed that 9 out of the 16 participants (56%) responded positively to the applied CA, suggesting that the PAPE effect may be individually dependent and should be carefully verified before implementation in a training program.

Effect of a Supplementary Periodized Complex Strength Training and Tapering Period on Postactivation Potentiation of Sport-Specific Explosive Performance in Adolescent National-Level Fencers

ABSTRACT

Kontochristopoulos, N, Bogdanis, GC, Paradisis, G, and Tsolakis, C. Effect of a supplementary periodized complex strength training and tapering period on postactivation potentiation of sport-specific explosive performance in adolescent national-level fencers. J Strength Cond Res 35(6): 1662-1670, 2021-This study examined the effects of strength training and tapering on countermovement jump (CMJ), change of direction (COD), and step-lunge (SL) after a conditioning activity in adolescent fencers. Twenty fencers (age: 15.8 ± 1.2 years) were randomly assigned to experimental (EXP, n = 10) group and control (CON, n = 10) group. EXP and CON groups performed 8 weeks of fencing training (4 times per week), while EXP group performed a supplementary strength training program twice per week, including a hypertrophy (first 2 weeks) and a complex strength training period (6 weeks). A 14-day tapering period with reduced training volume was then applied in both groups. Conditioning activity consisted of 3 × 3 seconds of maximal voluntary isometric contraction (MVIC; half-squat; knee angle = 90°), followed by either CMJ or COD or SL performance measurements in 3 different testing sessions 24 hours apart. There was no performance enhancement in all tests for both EXP and CON groups, after the conditioning MVIC before training (p > 0.05). After training, half-squat dynamic strength (1 repetition maximum [1RM]) was significantly increased only in the EXP group (from 74.8 ± 20.0 to 127.0 ± 28.9 kg, p = 0.001) and maintained after tapering. After tapering, baseline CMJ height was significantly increased only in the EXP group (from 27.2 ± 4.6 to 30.9 ± 3.8 cm, p = 0.003). Contrary to our hypothesis, the increase in 1RM and CMJ was not followed by a postactivation potentiation enhancement in all tests (p > 0.05), possibly because of the relatively low strength and jumping performance of fencers. Thus, adolescent high-level fencers do not exhibit a performance increase after MVIC, and this was not modified by the supplementary strength training protocol used.

Optimal Training Sequences to Develop Lower Body Force, Velocity, Power, and Jump Height: A Systematic Review with Meta-Analysis

BACKGROUND

Resistance training has been used to enhance a range of athletic abilities through correct manipulation of several variables such as training load, training volume, set configuration, and rest period.

OBJECTIVE

The aim of this systematic review and meta-analysis was to compare the acute and chronic responses of lower body cluster, contrast, complex, and traditional training across a range of athletic performance outcomes (1-repetition maximum squat strength, jump height, peak power, peak force, peak velocity, and sprint time).

METHODS

A database search was completed (SPORTDiscus, Medline and CINAHL) followed by a quality scoring system, which concluded with 41 studies being used in the meta-analysis. Effect sizes were calculated for acute and training intervention changes compared to baseline. For acute cluster training, effect sizes were used to represent differences between equated traditional and cluster sets.

RESULTS

Acutely, contrast and cluster training can be implemented to enhance and maintain velocity. Complex training does not acutely show a performance-enhancing effect on jump performance.

CONCLUSION

When looking to develop exercise-specific force, the exercise should be completed closer to set failure with fewer repetitions still able to be completed, which can be achieved using complex or high-volume contrast training to pre-fatigue the lighter exercise. When the objective is to improve velocity for the target exercise, it can be combined with a heavier contrast pair to create a postactivation performance enhancing effect. Alternatively, cluster set designs can be used to maintain high velocities and reduce drop-off. Finally, traditional training is most effective for increasing squat 1-repetition maximum.

Does Eccentric-only and Concentric-only Activation Increase Power Output?

PURPOSE

The aim of study was to evaluate changes in power output and bar velocity in the bench press throw (BPT) following the bench press (BP) exercise as a conditioning activity (CA) with concentric only (CONONLY) and eccentric only (ECCONLY) contractions.

METHODS

Thirty-two (n = 32) healthy strength-trained men participated in this study (age, 28.4 ± 4.5 yr; height, 177 ± 7.6 cm; body mass, 93.5 ± 9.3 kg; BP one-repetition maximum (1RM), 143.6 ± 17.5 kg). The experiment was performed following a randomized crossover design, where each participant performed 2 sets of 2 repetitions using the BP exercise as the CA at 90% 1RM ECCONLY, 90% 1RM CONONLY, 110% 1RM ECCONLY, or 130% 1RM ECCONLY contraction. The BPT was performed to assess changes in peak power (PP), mean power (MP), and peak velocity (PV), mean velocity (MV) before and after CA. The differences between analyzed variables before and after the CA were verified using ANOVA with repeated measures. Statistical significance was set at P < 0.05.

RESULTS

There were statistically significant differences between baseline and postactivation value of PP and PV in the BPT (P < 0.05) after the CA with ECCONLY contraction at 110% 1RM and at 130% 1RM as well between baseline and postactivation value of MV in the BPT (P < 0.05) after CA with contraction at 110% 1RM. There were no significant differences between baseline and postactivation values of PP, MP, PV, and MV in the BPT after the CA with CONONLY contraction at 90% 1RM and CA with ECCONLY contraction at 90% 1RM.

CONCLUSIONS

Partial movement with ECCONLY contraction is effective in short-term power output development, but only when the load used in the CA exceeds 100% 1RM.

Postactivation Performance Enhancement of Concentric Bench Press Throw After Eccentric-Only Conditioning Exercise

Krzysztofik, M, Wilk, M, Lockie, RG, Golas, A, Zajac, A, and Bogdanis, GC. Postactivation performance enhancement of concentric bench press throw after eccentric-only conditioning exercise. J Strength Cond Res XX(X): 000-000, 2020-This study examined changes in power output and bar velocity in the concentric-only bench press throw (CONONLY) after a sets of eccentric-only bench press exercises (ECCONLY) at 2 supramaximal loads. Thirteen strength-trained men participated in this study (age = 25.7 ± 1.9 years, body mass = 94.8 ± 8 kg, 1 repetition maximum [1RM] = 147 ± 14.2 kg, and strength training experience = 6.5 ± 2.2 years). The subjects performed 2 conditioning sets of the bench press exercise of 2 repetitions each, with a 5 minutes rest interval between sets, using the ECCONLY mode against 110% or 130% of concentric 1RM load. The 1 repetition of the CONONLY bench press throw with a load of 30% 1RM was performed before and 5 minutes after the conditioning activity (CA) to assess changes in peak power (PP) and peak velocity (PV). The differences between the analyzed variables before and after the CA were determined using a 2-way repeated measures analysis of variance. There was an increase of PP by 10.5 ± 6.0% (effect size [ES] = 0.34) and 9.9 ± 8.1% (ES = 0.33) for the 110 and 130% of concentric 1RM conditions, respectively, with no difference between the 2 conditions (p < 0.01 main effect time, no interaction). Similarly, PV increased by 5.9 ± 5.5% (ES = 0.40) and 6.1 ± 6.1% (ES = 0.43) for the 110 and 130% of concentric 1RM conditions, respectively, with no difference between the 2 conditions (p < 0.01 main effect time, no interaction). Activation with an ECCONLY contraction and loads exceeding 1RM are effective at improving power output and bar velocity during the CONONLY bench press throw.

Effect of a Blend of Zingiber officinale Roscoe and Bixa orellana L. Herbal Supplement on the Recovery of Delayed-Onset Muscle Soreness Induced by Unaccustomed Eccentric Resistance Training: A Randomized, Triple-Blind, Placebo-Controlled Trial

BACKGROUND

There is an increasing interest in the use of eccentric muscle exercise to improve physical condition, especially with regards to its health-related benefits. However, it is known that unaccustomed eccentric exercise causes muscle damage and delayed pain, commonly defined as "delayed onset muscle soreness" (DOMS). The efficacy of herbal preparations in subjects suffering from DOMS has been reported in a few previous studies with small or moderate outcome measures related to muscle recovery. The present study aimed to evaluate the effects of a polyherbal mixture containing whole Zingiber officinale Roscoe and Bixa orellana L., powders called ReWin(d), in young male athletes suffering from DOMS induced by a 1 h session of plyometric exercises.

METHODS

Thirty-three young male athletes participated in this randomized, Triple-blind, placebo-controlled trial: 17 of them assigned to the ReWin(d) group and 16 of them to the placebo group. Creatine kinase (CK) was measured as a muscle damage marker, pain was assessed using the Visual Analog Scale (VAS), muscle performance was measured through half-squat exercise (HS) monitored with an accelerometer (Encoder), and heart rate variability (HRV) was monitored for 5 min with the subjects in the supine position. All determinations were performed before and after the eccentric session and 24, 48, and 72 h after the session.

RESULTS

The eccentric exercise session caused an increase in CK at 24 and 48 h after exercise intervention in both groups (p < 0.001). There was no interaction between groups regarding muscle damage. The pain increased after the training session in both groups (p < 0.001), and a significant interaction was observed between groups at 48 h after exercise (p = 0.004). Lower limb muscular power showed a significant interaction between groups 24 h after exercise (p = 0.049); the placebo group showed a reduction in muscle power compared to the ReWin(d) group. The LF/HF ratio decreased significantly at 72 h after exercise in the herbal group but not in the placebo group.

CONCLUSION

The herbal supplement maintained the maximum power of the lower limbs and attenuated muscle pain.

CLINICAL TRIAL REGISTRATION

www.ClinicalTrials.gov, identifier NCT03961022.

Individual and Combined Effect of Inter-repetition Rest and Elastic Bands on Jumping Potentiation in Resistance-Trained Men

Nickerson, BS, Williams, TD, Snarr, RL, and Park, K-S. Individual and combined effect of inter-repetition rest and elastic bands on jumping potentiation in resistance-trained men. J Strength Cond Res 33(8): 2087-2093, 2019-The purpose of this study was to determine the individual and combined effects of cluster sets (CS) and elastic bands for jumping potentiation in resistance-trained men. Twelve resistance-trained men (age: 22 ± 3 years) participated in this study. In a random order, participants completed 1 set of 3 repetitions at 85% 1-repetition maximum for the parallel back squat: (a) traditional set with continuous repetitions; (b) continuous repetitions with elastic bands (BANDS); (c) CS with 30 seconds of rest between each repetition (CS30); and (d) CS with 30 seconds of rest between each repetition and elastic bands (CS + BANDS). Vertical jump height (JH) and peak power (PP) were measured before exercise (baseline) and at 1, 4, 7, and 10 minutes after exercise for each condition. Results revealed that PP at 10 minutes was significantly higher than 7 minutes for BANDS (p = 0.035) and that 4 and 7minutes were both significantly higher than baseline for CS + BANDS (p = 0.008 and 0.031, respectively). No other differences were observed. There were medium effect sizes (ESs) for PP with BANDS (ES = 0.58 at 10 minutes), CS30 (ES = 0.53 and 0.64 at 7 and 10 minutes, respectively), and CS + BANDS (ES = 0.64, 0.78, and 0.66 at 4, 7, and 10 minutes, respectively). All remaining ES for JH and PP were trivial to small. Based on the moderate magnitude of effect, BANDS, CS30, and CS + BANDS were effective at potentiating vertical jump power. CS + BANDS is a more practical approach to potentiate vertical jump power when athletes are under strict time restraints.

Postactivation Potentiation of Bench Press Throw Performance Using Velocity-Based Conditioning Protocols with Low and Moderate Loads

This study examined the acute effects of the bench press exercise with low and moderate loads as well as with two predetermined movement velocity loss percentages on bench press throw performance and surface electromyographic (sEMG) activity. Ten trained men completed 5 main trials in randomized and counterbalanced order one week apart. Mean propulsive velocity (MPV), peak velocity (PV) and sEMG activity of prime movers were evaluated before and periodically for 12 minutes of recovery under five conditions: using loads of 40 or 60% of 1 RM, until mean velocity dropped to 90 or 70%, as well as a control condition (CTRL). MPV and PV were increased 4-12 min into recovery by 4.5-6.8% only after the 60%1RM condition during which velocity dropped to 90% and total exercise volume was the lowest of all conditions (p < 0.01, Hedges’ g = 0.8-1.7). When peak individual responses were calculated irrespective of time, MPV was increased by 9.2 ± 4.4 (p < 0.001, Hedges’ g = 1.0) and 6.1 ± 3.6% (p < 0.001, Hedges’ g = 0.7) under the two conditions with the lowest total exercise volume irrespective of the load, i.e. under the conditions of 40 and 60% 1RM where velocity was allowed to drop to 90%. sEMG activity of the triceps was significantly greater when peak individual responses were taken into account only under the 60%1RM condition when velocity dropped to 90% (p < 0.05, Hedges’ g = 0.4). This study showed that potentiation may be maximized by taking into account individual fatigue profiles using velocity-based training.

Postactivation Potentiation and Change of Direction Speed in Elite Academy Rugby Players

Marshall, J, Turner, AN, Jarvis, PT, Maloney, SJ, Cree, JA, and Bishop, CJ. Postactivation potentiation and change of direction speed in elite academy rugby players. J Strength Cond Res 33(6): 1551-1556, 2019-This study investigated the effect of preceding proagility sprints with maximal isometric squats to determine if postactivation potentiation (PAP) could be harnessed in change of direction speed. Sixteen elite under-17 rugby union players (age: 16 ± 0.41 years; body mass: 88.7 ± 12.1 kg; height: 1.83 ± 0.07 m) from an Aviva Premiership rugby club were tested. Subjects performed a change of direction specific warm-up, followed by 2 baseline proagility tests. After 10-minute recovery, 3 × 3-second maximal isometric squats with a 2-minute recovery between sets were completed as a conditioning activity (CA) on a force plate where peak force and mean rate of force development over 300 milliseconds were measured. The proagility test was repeated at set time intervals of 1, 3, 5, and 7 minutes after the CA. Overall proagility times were significantly slower (p < 0.05) at 1 minute post-CA compared with the baseline (3.3%), with no significant differences occurring at 3, 5, or 7 minutes post-CA. Therefore, it appears that performing multiple sets of maximal isometric squats do not enhance proagility performance.

Comparison Between Unilateral and Bilateral Plyometric Training on Single- and Double-Leg Jumping Performance and Strength

Bogdanis, GC, Tsoukos, A, Kaloheri, O, Terzis, G, Veligekas, P, and Brown, LE. Comparison between unilateral and bilateral plyometric training on single- and double-leg jumping performance and strength. J Strength Cond Res 33(3): 633-640, 2019-This study compared the effects of unilateral and bilateral plyometric training on single- and double-leg jumping performance, maximal strength, and rate of force development (RFD). Fifteen moderately trained subjects were randomly assigned to either a unilateral (U, n = 7) or bilateral group (B, n = 8). Both groups performed maximal effort plyometric leg exercises 2 times per week for 6 weeks. The B group performed all exercises with both legs, whereas the U group performed half the repetitions with each leg, so that total exercise volume was the same. Jumping performance was assessed by countermovement jumps (CMJs) and drop jumps (DJs), whereas maximal isometric leg press strength and RFD were measured before and after training for each leg separately and both legs together. Countermovement jump improvement with both legs was not significantly different between U (12.1 ± 7.2%) and B (11.0 ± 5.5%) groups. However, the sum of right- and left-leg CMJ only improved in the U group (19.0 ± 7.1%, p < 0.001) and was unchanged in the B group (3.4 ± 8.4%, p = 0.80). Maximal isometric leg press force with both legs was increased similarly between groups (B: 20.1 ± 6.5%, U: 19.9 ± 6.2%). However, the sum of right- and left-leg maximal force increased more in U compared with B group (23.8 ± 9.1% vs. 11.9 ± 6.2%, p = 0.009, respectively). Similarly, the sum of right- and left-leg RFD0-50 and RFD0-100 were improved only in the U group (34-36%, p < 0.01). Unilateral plyometric training was more effective at increasing both single- and double-leg jumping performance, isometric leg press maximal force, and RFD when compared with bilateral training.

What are the best isometric exercises of muscle potentiation?

PURPOSE

The aim of this study was to follow post-activation potentiation (PAP), low-frequency fatigue (LFF), metabolic-induced fatigue and post-contractile depression (PCD) in response to different isometric muscle contraction modalities.

METHODS

Young healthy men (N = 120) were randomly assigned to one of ten exercise modality groups which differed in contraction duration (5-60 s), activation pattern (intermittent or continuous contractions), activation mode (voluntary or stimulated), and intensity [maximal or submaximal (50%)]. Isometric maximal voluntary contraction (MVC), and electrically induced knee extension torque were measured at baseline and at regular intervals for 60 min after exercise.

RESULTS

Muscle contraction modalities involving 5 s MVC were the most effective for PAP, whereas the lowest PAP effectiveness was found after the 12 × 5-MVC modality. After all of the 5-15 s MVC and 6 × 5-MVC protocols, the potentiation of the twitch rate was significantly higher than that recorded after continuous 30-60 s protocols (P < 0.001). Tetanic maximal torque (100 Hz) potentiation occurred 5 min after 15-30 s repetitive MVC modalities and after modality involving 15 electrical stimuli (P < 0.05).

CONCLUSIONS

The findings demonstrate that post-activation potentiation was most effective after brief duration continuous and repetitive MVC protocols. To understand the resultant warm-up of motor performance, it is necessary to recognize the coexistence of muscle PAP, tetanic maximal force potentiation, rapid recovery of metabolic muscle, and central muscle activation processes, as well as prolonged LFF and prolonged PCD.

Muscle Fiber and Performance Changes after Fast Eccentric Complex Training

INTRODUCTION

The purpose of this study was to examine the effects of a short-term fast eccentric and ballistic complex training program on muscle power, rate of force development (RFD), muscle fiber composition, and cross-sectional area (CSA).

METHODS

Sixteen male physical education students were randomly assigned to either a training group (TG, n = 8) or a control group (n = 8). The TG followed a 6-wk low volume training program, including fast eccentric squat training with an individually optimized load of 74% ± 7% of maximal half-squat strength (1RM) twice per week and a ballistic training session with loaded (30% 1RM) and unloaded jump squats, once per week, all combined with unloaded plyometric jumps.

RESULTS

Half squat 1RM was increased in the TG from 1.87 ± 0.28 to 2.14 ± 0.31 kg per kilogram body mass (14.4% ± 9.3%, P = 0.01). The percentage of types I, IIA, and IIX fibers were similar in the two groups at pretesting and did not change after the intervention period (P = 0.53-0.89). Muscle fiber CSA increased in all fiber types by 8.3% to 11.6% (P = 0.02 to 0.001) in TG only. Countermovement jump height and peak power measured at five different external loads (0%-65% of 1RM) only increased in the TG by approximately 20% to 36% (P < 0.01) and approximately 16% to 22% (P < 0.01), respectively. Peak ground reaction force during jump squats remained unchanged in both groups, whereas RFD increased in the TG only (40%-107%, P = 0.001).

CONCLUSIONS

A combination of low-volume fast eccentric and ballistic jump squat training with plyometric jumps in a strength-power potentiation complex format, induced substantial increases in peak leg muscle power, RFD, and maximal strength, accompanied by gains in CSA of all muscle fiber types, without a reduction in fast twitch fiber composition.

Unilateral Conditioning Contractions Enhance Power Output in Elite Short Track Speed Skaters

The objective of the present study was to assess the effect of unilateral lower-body-conditioning muscle contractions during multiple sets of fatiguing repeated jumps in elite athletes. Five elite short-track speed-skating athletes performed 9 sets of 6 maximal consecutive jumps on 2 separate occasions: with (COND) and without (CTRL) preliminary voluntary conditioning contractions (CC) 5 min before the beginning of the sets. The CC consisted of 2 consecutive 3 s maximal unilateral isometric squats against a fixed bar, resulting in a 6 s overall isometric contraction per leg. For each set, power output (PO) was measured using a linear position transducer and averaged over the 6 corresponding repeated jumps. The results showed that PO was significantly greater during the test in COND than in CTRL ( p <0.01). PO significantly decreased with sets, by 19.4±4.7  and 15.2±7.6% ( p <0.001) between the first and last set in COND and CTRL, respectively. A 2×3 s maximal unilateral isometric CC, performed 5 min before unloaded repeated jumps, significantly increased mean PO. These results suggest that unilateral conditioning contractions can enhance performance in subsequent bilateral repeated jumps.

Effects of Blood-Flow Restriction Combined With Postactivation Potentiation Stimuli on Jump Performance in Recreationally Active Men

Miller, RM, Keeter, VM, Freitas, EDS, Heishman, AD, Knehans, AW, Bemben, DA, and Bemben, MG. Effects of blood-flow restriction combined with postactivation potentiation stimuli on jump performance in recreationally active men. J Strength Cond Res 32(7): 1869-1874, 2018-Whole-body vibration (WBV) and maximum voluntary contractions (MVCs) combined with blood-flow restriction (BFR) to augment postactivation potentiation have yet to be examined. Therefore, the purpose of this investigation was to examine the augmented effects of postactivation potentiation when WBV and MVC are combined with BFR. Twenty men (21.8 ± 2.6 years, 180.5 ± 6.2 cm and 84.5 ± 12.1 kg) completed the study. Participants completed 3 testing sessions in a randomized design that included one of the following: (a) control (CON), (b) WBV and WBV combined with BFR (WBV + BFR), or (c) MVC and MVC combined with BFR (MVC + BFR). Jump height and power were recorded for 3 trials, PRE and POST jump height (cm) mean ± SD for each were as follows: CON 58.9 ± 8.6 and 57.9 ± 8.6, WBV 58.2 ± 8.1 and 59.9 ± 8.1, WBV + BFR 58.7 ± 7.6 and 60.2 ± 8.1, MVC 59.7 ± 7.4 and 60.2 ± 8.6, and MVC + BFR 57.7 ± 7.9 and 59.4 ± 8.1. PRE and POST jump power (W) mean ± SD for each were as follows: CON 1,224.3 ± 221.5 and 1,234.3 ± 189.2, WBV 1,251.1 ± 230.4 and 1,266.1 ± 215.7, WBV + BFR 1,265.8 ± 207.9 and 1,259 ± 223.3, MVC 1,264.7 ± 211.9 and 1,263.5 ± 236.5, and MVC + BFR 1,252.3 ± 222.0 and 1,294.6 ± 256.6. Significant differences were revealed in jump height between the 5 interventions (p < 0.01), WBV (p < 0.01), WBV + BFR (p < 0.01), and MVC + BFR (p < 0.01) revealed significant differences in time but no differences in jump power. In conclusion, the results of this study indicate that WBV, WBV + BFR, and MVC + BFR significantly improve jump height and time in air but not jump power.

Acute Effect of Upper and Lower Body Postactivation Exercises on Shot Put Performance

Kontou, EI, Berberidou, FT, Pilianidis, TC, Mantzouranis, NI, and Methenitis, SK. Acute effect of upper and lower body postactivation exercises on shot put performance. J Strength Cond Res 32(4): 970-982, 2018-The purpose of this study was to investigate the effect of different types of upper and lower' extremities exercises on acute increase of shot put performance, in moderate experienced throwers. Eight (n = 8) males and 9 (n = 9) female throwers participated in this study. Their bench press and squat maximum strength were measured while their shot put performance from power position was evaluated before and after 4 interventions: (a) plyometric push-ups (Plyo), (b) 6 s isometric push-ups (Iso), (c) 3 countermovement jumps (CMJs) and (d) 10 reps. of skipping (Skip). Interventions were performed in counterbalanced order with a 48-hour interval. Significant increase (p < 0.05) of shot put performances was observed after Plyo, Iso, and CMJ (range: 2.30 ± 1.82%-5.72 ± 4.32%). In addition, Iso induced the highest increase while Skip did not induce any improvement of throwing performance. The highest increases were recorded in men's performance after CMJ (5.72 ± 4.32%) while in women's performance after Iso (3.59 ± 2.7%). Javelin and discus throwers increase higher their performance after CMJs while shot putters after Iso. Significant correlations were found between training experience, maximum/relative strength, shot put performance and increase of throwing performance (%) after the interventions (r: 0.519-0.991, p < 0.05). Percentage increase of performance between Iso and Plyo have negative correlations (r: -0.569, p < 0.05) in contrast of those between Skip and CMJ (r: 0.710, p < 0.05). These results suggest that upper or lower body postactivation interventions may acutely increase the throwing performance. However, experience and strength are significant determinant of this increase.

Using the Split Squat to Potentiate Bilateral and Unilateral Jump Performance

Bishop, CJ, Tarrant, J, Jarvis, PT, and Turner, AN. Using the split squat to potentiate bilateral and unilateral jump performance. J Strength Cond Res 31(8): 2216-2222, 2017-The purpose of this study was to examine if a split squat conditioning exercise with no or light loads could potentiate unilateral and bilateral jump performance. Twelve semiprofessional rugby players (age: 22.3 ± 1.4 years; height: 1.84 ± 0.05 m, mass: 92.4 ± 9.6 kg) from the English National League 1 performed a series of unilateral and bilateral countermovement jumps (CMJ) and broad jumps (BJ) over the course of 2 testing days. Both testing days involved performing baseline jumps before completing 2 sets of 10 repetitions of a split squat, this completed with either bodyweight (testing session 1) or a 30 kg weighted vest (testing session 2). A 5-minute recovery period was permitted both after the warm-up and the completion of the split squat exercise. Significantly larger bilateral jump scores were reported after completion of the bodyweight split squat: CMJ (p = 0.001, ES = 0.44, [mean difference 2.517]), BJ (p = 0.001, ES = 0.37, [mean difference 3.817]), and the weighted vest split squat; CMJ (p = 0.001, ES = 0.8, [mean difference 4.383]), BJ (p = 0.001, ES = 0.68, [mean difference 6.817]). The findings of this study demonstrate that no or light loads of a split squat conditioning exercise are able to potentiate bilateral jump performance in semiprofessional rugby players without the need for expensive weight room equipment. As such, this may provide coaches with a viable option of enhancing bilateral jump performance as part of a warm-up or on-field conditioning practice.

Can Different Complex Training Improve the Individual Phenomenon of Post-Activation Potentiation?

The aims of the present study were (a) to determine whether the two types of complex training and vibration complex training would improve the individual phenomenon of post-activation potentiation (PAP) for every athlete in a team setting; and (b) to compare the acute effect of resistance and plyometric exercise, whole body vibration, complex training and vibration complex training on vertical jump performance. The participants were ten male division I college volleyball and basketball players. They were asked to perform three vertical jumps as a pre-test and were then randomly assigned to one of five PAP protocols, resistance exercise using half squat exercise, plyometric exercise using drop jumps with individualized drop height, whole body vibration using squats on a vibration plate, complex training combining resistance exercise with plyometric exercise, vibration complex training combining whole body vibration with plyometric exercise. Three vertical jumps were performed four minutes after the PAP protocol as a post-test. A two-way repeated-measures analysis of variance was used to examine the differences among the five PAP protocols and between the two testing times. Our results showed that the post-test results were significantly improved compared to the pre-test for the vertical jump height (p = .015) in all PAP protocols. There was, however, an individual phenomenon of PAP in the response to all PAP protocols. In conclusion, this study found that resistance and plyometric exercise, whole body vibration, complex training and vibration complex training induce similar group PAP benefits. However, some athletes decreased their performances in some of the exercises in the study. Therefore, it is not recommended for coaches to arrange the exercises in a team setting.

Potentiation Effects of Half-Squats Performed in a Ballistic or Nonballistic Manner

This study examined and compared the acute effects of ballistic and nonballistic concentric-only half-squats (COHSs) on squat jump performance. Fifteen resistance-trained men performed a squat jump 2 minutes after a control protocol or 2 COHSs at 90% of their 1 repetition maximum (1RM) COHS performed in a ballistic or nonballistic manner. Jump height (JH), peak power (PP), and allometrically scaled peak power (PPa) were compared using three 3 × 2 repeated-measures analyses of variance. Statistically significant condition × time interaction effects existed for JH (p = 0.037), PP (p = 0.041), and PPa (p = 0.031). Post hoc analysis revealed that the ballistic condition produced statistically greater JH (p = 0.017 and p = 0.036), PP (p = 0.031 and p = 0.026), and PPa (p = 0.024 and p = 0.023) than the control and nonballistic conditions, respectively. Small effect sizes for JH, PP, and PPa existed during the ballistic condition (d = 0.28-0.44), whereas trivial effect sizes existed during the control (d = 0.0-0.18) and nonballistic (d = 0.0-0.17) conditions. Large statistically significant relationships existed between the JH potentiation response and the subject's relative back squat 1RM (r = 0.520; p = 0.047) and relative COHS 1RM (r = 0.569; p = 0.027) during the ballistic condition. In addition, large statistically significant relationship existed between JH potentiation response and the subject's relative back squat strength (r = 0.633; p = 0.011), whereas the moderate relationship with the subject's relative COHS strength trended toward significance (r = 0.483; p = 0.068). Ballistic COHS produced superior potentiation effects compared with COHS performed in a nonballistic manner. Relative strength may contribute to the elicited potentiation response after ballistic and nonballistic COHS.

Acute Improvement of Vertical Jump Performance After Isometric Squats Depends on Knee Angle and Vertical Jumping Ability

Tsoukos, A, Bogdanis, GC, Terzis, G, and Veligekas, P. Acute improvement of vertical jump performance after isometric squats depends on knee angle and vertical jumping ability. J Strength Cond Res 30(8): 2250-2257, 2016-This study examined the acute effects of maximum isometric squats at 2 different knee angles (90 or 140°) on countermovement jump (CMJ) performance in power athletes. Fourteen national-level male track and field power athletes completed 3 main trials (2 experimental and 1 control) in a randomized and counterbalanced order 1 week apart. Countermovement jump performance was evaluated using a force-plate before and 15 seconds, 3, 6, 9, and 12 minutes after 3 sets of 3 seconds maximum isometric contractions with 1-minute rest in between, from a squat position with knee angle set at 90 or 140°. Countermovement jump performance was improved compared with baseline only in the 140° condition by 3.8 ± 1.2% on the 12th minute of recovery (p = 0.027), whereas there was no change in CMJ height in the 90° condition. In the control condition, there was a decrease in CMJ performance over time, reaching -3.6 ± 1.2% (p = 0.049) after 12 minutes of recovery. To determine the possible effects of baseline jump performance on subsequent CMJ performance, subjects were divided into 2 groups ("high jumpers" and "low jumpers"). The baseline CMJ values of "high jumpers" and "low jumpers" differed significantly (CMJ: 45.1 ± 2.2 vs. 37.1 ± 3.9 cm, respectively, p = 0.001). Countermovement jump was increased only in the "high jumpers" group by 5.4 ± 1.4% (p = 0.001) and 7.4 ± 1.2% (p = 0.001) at the knee angles of 90 and 140°, respectively. This improvement was larger at the 140° angle (p = 0.049). Knee angle during isometric squats and vertical jumping ability are important determinants of the acute CMJ performance increase observed after a conditioning activity.

The Effects of Eccentric Conditioning Stimuli on Subsequent Counter-Movement Jump Performance

The eccentric phase in a stretch-shortening cycle is an important determinant of subsequent concentric performance, but there is little information on high-intensity eccentric preconditioning. The purpose of this study was to determine the effects of varying degrees of eccentric conditioning stimuli on subsequent counter-movement jump (CMJ) performance. Fourteen participants (age, 28.5 ± 5.0 years; height, 172.7 ± 6.7 cm; body mass, 74.3 ± 11.9 kg) performed CMJ trials on 3 separate test sessions at least 96 hours apart in a crossover randomized counterbalanced study. Peak power (Ppeak) and vertical displacement (Dmax) were measured before and at 3, 6, 9, and 12 minutes (T3-12) postcontrol (0RM), 105% (105RM), and 125% (125RM) 1RM eccentric hip sled. The differences in vertical jump performance parameters between 0RM and eccentric preloading conditions (105RM and 125RM) and the differences within condition between control time point and posteccentric load time course T3, T6, T9, and T12 were analyzed for statistical significance via unequal variance t statistic. Statistical significance was set at p ≤ 0.05. Significantly higher Ppeak, compared with 0RM (4143 ± 754 W) was seen at T3 and T6 in both 105RM (4305 ± 876 and 4237 ± 842 W) and 125RM (4314 ± 848 and 4264 ± 768 W). Compared with 0RM (42.2 ± 7.8 cm), corresponding Dmax, was also significantly improved at T3 in both 105RM (44.5 ± 7.3 cm) and 125RM (44.3 ± 8.3 cm) and at T6 in 105RM (44.7 ± 7.7 cm). Compared with baseline (43.2 ± 7.2 cm), there was significantly higher Dmax at T3 and T6 in 105RM. In conclusion, high-intensity preconditioning eccentric contraction at 105 and 125% 1RM was effective in improving CMJ power and height at 3 and 6 minutes after loading. Thus, power athletes and coaches can consider the application of eccentric preconditioning in warm-up routines.

Early phase interference between low-intensity running and power training in moderately trained females

PURPOSE

The aim of the study was to investigate the effects of low-intensity running performed immediately after lower-body power-training sessions on power development.

METHODS

Twenty young females participated in 6 weeks, 3/week, of either lower body power training (PT) or lower body power training followed by 30 min of low-intensity running (PET) eliciting 60-70 % of maximal heart rate. The following were measured before and after the training period: counter-movement jump, isometric leg press force and rate of force development (RFD), half squat 1-RM, vastus lateralis fiber type composition and cross sectional area, resting intramuscular fiber conduction velocity (MFCV), and heart rate during the modified Bruce treadmill test.

RESULTS

Counter-movement jump height and peak power increased after PT (10.7 ± 6.2 and 12.9 ± 18.7 %, p < 0.05) but not after PET (3.4 ± 7.6 and 5.11 ± 10.94 %, p > 0.05). Maximum isometric force, RFD, and half squat 1-RM increased similarly in both groups. Muscle fiber type composition was not altered in either group. Muscle fiber cross sectional area increased only after PT (17.5 ± 17.4, 14.5 ± 10.4, 20.36 ± 11.3 %, in type I, IIA, and IIX fibers, respectively, p < 0.05). Likewise, mean MFCV increased with PT only (before: 4.53 ± 0.38 m s(-1), after: 5.09 ± 0.39 m s(-1), p = 0.027). Submaximal heart rate during the Bruce treadmill test remained unchanged after PT but decreased after PET.

CONCLUSION

These results suggest that low-intensity running performed after lower-body power training impairs the exercise-induced adaptation in stretch-shortening cycle jumping performance (vertical jump height, peak power), during the first 6 weeks of training, which may be partially linked to inhibited muscle fiber hypertrophy and muscle fiber conduction velocity.