This study investigated redistributing long inter-set rest intervals into shorter but more frequent intervals at 2 different concentric velocities. Resistance-trained men performed 4 randomised isokinetic unilateral knee extension protocols, 2 at 60°·s−1 and 2 at 360°·s−1. At each speed, subjects performed 40 repetitions with 285 s of rest using traditional sets (TS; 4 sets of 10 with 95 s of inter-set rest) and rest-redistribution (RR; 20 sets of 2 with 15 s inter-set rest). Before and at 2, 5, and 10 min after exercise, tensiomyography (TMG) and oxygenation (near-infrared spectroscopy; NIRS) were measured. NIRS was also measured during exercise, and rating of perceived exertion (RPE) was recorded after every 10 repetitions. At both speeds, RR displayed greater peak torque, total work, and power output during latter repetitions, but there were no differences between TS or RR when averaging all 40 repetitions. The RPE was less during RR at both speeds (p < 0.05). RR increased select muscle oxygen saturation and blood flow at both speeds. There were no effects of protocol on TMG, but effect sizes favoured a quicker recovery after RR. RR was likely beneficial in maintaining performance compared with the latter parts of TS sets and limiting perceived and peripheral fatigue. Novelty Although effective at slow velocities, rest-redistribution was likely more effective during high-velocity movements in this study. Rest-redistribution maintained the ability to produce force throughout an entire range of motion. Rest-redistribution reduced RPE during both high-velocity and high-force movements.

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.

Krzysztofik, M, Wilk, M, Pisz, A, Kolinger, D, Tsoukos, A, Zając, A, Stastny, P, and Bogdanis, GC. Acute effects of varied back squat activation protocols on muscle-tendon stiffness and jumping performance. J Strength Cond Res 37(7): 1419–1427, 2023—Intensity, movement velocity, and volume are the principal factors to successfully use postactivation performance enhancement. Therefore, 15 resistance-trained volleyball players completed 3 different back squat configurations as a conditioning activity (CA) in randomized order: (a) 3 sets of 3 repetitions at 85% 1RM (HL); (b) a single set of back squats at 60% 1RM until 10% mean velocity loss (VB); (c) and 2 sets of back squats at 60% 1RM until 10% mean velocity loss (2VB) on subsequent countermovement jump performance, Achilles tendon, and vastus lateralis stiffness with concomitant front thigh skin surface temperature assessment. The measurements were performed 5 minutes before the CA and at 2, 4, 6, 8, and 10 minutes. The jump height was significantly increased in the second minute and at peak, post-CA compared with baseline for all conditions (p = 0.049; ES = 0.23 and p < 0.001; ES = 0.37). Skin surface temperature was significantly increased for all post-CA time points compared with baseline in the 2VB condition (p from <0.001–0.023; ES = 0.39–1.04) and in the fourth minute and at peak post-CA in HL condition (p = 0.023; ES = 0.69 and p = 0.04; ES = 0.46), whereas for the VB condition, a significant decrease in peak post-CA was found (p = 0.004; ES = −0.54). Achilles tendon stiffness was significantly decreased for second, fourth, eighth, 10th, and peak post-CA in comparison to baseline for all conditions (p from p = 0.004–0.038; ES = −0.47 to −0.69). Vastus lateralis stiffness was significantly decreased for peak post-CA compared with baseline for all conditions (p = 0.017; ES = −0.42). We recommend using a single set of barbell squats with a 10% velocity loss as a mechanism of fatigue control to acutely improve jump height performance and avoid unnecessary increases in training volume.

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 &lt; 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 &lt; 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.

The intrathoracic pressure and breathing strategy on bench press (BP) performance is highly discussed in strength competition practice. Therefore, the purpose of this study was to analyze whether different breathing techniques can influence the time and track characteristics of the sticking region (SR) during the 1RM BP exercise. 24 healthy, male adults (age 23 ± 2.4 yrs., body mass 85 ± 9.2 kg, height 181 ± 5.4 cm) performed a 1 repetition BP using the breathing technique of Valsalva maneuver (VM), hold breath, lung packing (PAC), and reverse breathing (REVB), while maximum lifted load and concentric phase kinematics were recorded. The results of ANOVA showed that the REVB breathing decreased absolute (p < 0.04) and relative lifted load (p < 0.01). The VM showed lower (p = 0.01) concentric time of the lift than the other breathing techniques. The VM and PAC showed lower SR time than other breathing techniques, where PAC showed a lower SR time than VM (p = 0.02). The PAC techniques resulted in shorter SR and pre-SR track than other breathing techniques and the REVB showed longer SR track than the other considered breathing techniques (p = 0.04). Thus, PAC or VM should be used for 1RM BP lifting according to preferences, experiences and lifting comfort of an athlete. The hold breath technique does not seem to excessively decrease the lifting load, but this method will increase the lifting time and the time spend in the sticking region, therefore its use does not provide any lifting benefit. The authors suggest that the REVB should not be used during 1 RM lifts.