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.

Effects of Priming with Light vs. Heavy Loads on Weightlifting Performance

BACKGROUND/OBJECTIVES

The purpose of the study was to investigate the effects of a priming training session with either a light or heavy load snatch and clean pulls on weightlifting performance.

METHODS

Twelve well-trained weightlifters (seven males and five females) participated in the study. The athletes followed a counterbalanced study design comparing three treatments, including a day of rest (control) and two priming sessions involving two different weightlifting derivatives-the snatch and the clean pulls-which were performed either with 80% of the one-repetition maximum (1-RM) (LP) or with 110% of the 1-RM (HP). Twenty-four hours later, the 1-RM strength test for the snatch and clean and jerk, as well as the barbell kinematic characteristics at 100% of the 1-RM in the snatch and clean and jerk, were measured. The rate of perceived exertion (RPE) was measured following the priming sessions.

RESULTS

Performance in snatch remained unchanged following the LP and HP. However, performance in the clean and jerk increased significantly by 3.1% following the HP compared to the control. No significant differences were observed in barbell kinematics. The RPE was significantly higher for HP compared to LP.

CONCLUSIONS

These results suggest that an HP performed 24 h prior to the 1-RM evaluation in weightlifting may have significantly increased performance in the clean and jerk. These changes may not be explained by barbell kinematics.

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.

The Importance of Recovery in Resistance Training Microcycle Construction

Systemic resistance training aims to enhance performance by balancing stress, fatigue and recovery. While fatigue is expected, insufficient recovery may temporarily impair performance. The aim of this review was to examine evidence regarding manipulation of resistance training variables on subsequent effects on recovery and performance. PubMed, Medline, SPORTDiscus, Scopus and CINAHL were searched. Only studies that investigated recovery between resistance training sessions were selected, with a total of 24 articles included for review. Training to failure may lengthen recovery times, potentially impairing performance; however, it may be suitable if implemented strategically ensuring adequate recovery between sessions of similar exercises or muscle groups. Higher volumes may increase recovery demands, especially when paired with training to failure, however, with wide variation in individual responses, it is suggested to start with lower volume, monitor recovery, and gradually increase training volume if appropriate. Exercises emphasising the lower body, multi-joint movements, greater muscle recruitment, eccentric contractions, and/or the lengthened position may require longer recovery times. Adjusting volume and frequency of these exercises can affect recovery demands depending on the goals and training logistics. Daily undulating programming may maximise performance on priority sessions while maintaining purposeful and productive easy days. For example, active recovery in the form of training opposing muscle groups, light aerobic cardio, or low-volume power-type training may improve recovery and potentially elicit a post activation potentiation priming effect compared to passive recovery. However, it is possible that training cessation may be adequate for allowing sufficient recovery prior to sessions of importance.

Post-Activation Performance Enhancement (PAPE) Increases Jumping Power in Elite Female Volleyball Athletes

This study investigated PAPE effects of two conditioning activities (CA) and recovery times on the peak jumping power (PP) of elite female volleyball athletes. Players performed CA separately: three sets of three repetitions of back squats with 85% of 1RM (BS) or one set of five depth drops (DD). PP was measured with countermovement (CMJ) and squat jumps (SJ) before (pre-test) and two minutes (post-test 1) and six hours (post-test 2) after each CA. BS significantly reduced PP at post-test 1 (CMJ and SJ: p < 0.04, d between -0.36 and -0.28). At post-test 2, following BS, PP for both jump forms was significantly greater than at post-test 1 (p < 0.001, d between 0.54 and 0.55) and at pre-test (p < 0.048, d between 0.21 and 0.30). DD increased PP significantly (CMJ and SJ p < 0.05, d between 0.40 and 0.41) relative to pre-test at post-test 2 (there was no significant difference between pre-test and post-test 1). Comparing BS with DD, there were no significant differences (p > 0.05). The greatest PAPE effects were observed six hours after BS. CA are recommended for female athletes to improve jumping performance, but individual responses should be determined prior to use.

The Effects of Low-Load Squat Jump and Maximal Isometric Priming Exercise on Muscular Performance and Perceptual State

ABSTRACT

Harrison, PW, James, LP, Jenkins, DG, McGuigan, MR, Holmberg, PM, and Kelly, VG. The effects of low-load squat jump and maximal isometric priming exercise on muscular performance and perceptual state. J Strength Cond Res 38(1): 1-9, 2024-The aim of this study was to examine responses at 3 and 27 hours after low-load jump squat (LL) and maximal isometric half-squat (ISO) priming stimuli. Fifteen resistance-trained males performed LL (4 × 3 at 20% 1 repetition maximum [1RM]), ISO (4 × 3 seconds), and control (CON) activities (standardized warm-up) in a randomized and counterbalanced order. Countermovement jump (CMJ) and isometric midthigh pull tests were conducted to assess performance changes after priming and CON activities. No clear changes in CMJ measures were found after priming activities compared with CON. However, small effect size improvements were found after priming stimuli completed on the same day. A 2.9% decrease in concentric phase duration (CI = 0.3-5.9, p = 0.333, Cliff's delta = -0.156) and a 9.1% increase in RSImod (CI = 0.2-12.3, p = 0.151, Cliff's delta = -0.218) occurred at 3 hours after LL compared with CON. Braking phase duration (CI = 0.8-10.6, p = 0.333, Cliff's delta = -0.213) was 2.9% shorter at 3 hours after ISO compared with CON. No clear changes in isometric peak force occurred after priming activities compared with CON. Additionally, questionnaires were completed to assess perceptual state and perceived effectiveness of the priming stimulus to influence performance. An increase in the "effect of activity" was perceived at 3 hours after LL and ISO (p = 0.013-0.044, Cliff's delta = 0.578-0.6) and at 27 hours after ISO (p = 0.99, Cliff's delta = 0.173) compared with CON. An increase in "muscular heaviness" was also reported at 3 hours after ISO compared with CON (p = 0.199, Cliff's delta = 0.320). The collective findings suggest limited benefits over the day after LL and ISO priming stimuli. However, as there was substantial variation in individual responses, the relative nature of priming responses should be considered when prescribing similar strategies in practical environments.

Sprint Resisted and Assisted Priming for Peak Performance

ABSTRACT

Krzysztof, K, Aleksander, M, Adam, Z, and Krzysztofik, M. Sprint resisted and assisted priming for peak performance. J Strength Cond Res 37(12): 2354-2361, 2023-This study aimed to investigate resisted and assisted sprint, or a combination of both, as a conditioning activity (CA) on creatine kinase activity, biceps femoris stiffness, postactivation performance enhancement (PAPE), and priming in a sprint. Ten female sprinters (age: 20.1 ± 2.3 years, body mass: 56.4 ± 4.2 kg, body height: 171 ± 5 cm, training experience: 5.6 ± 2 years) participated. Before the warm-up, blood samples were drawn to determine creatine kinase at baseline. After the warm-up, biceps femoris stiffness was determined, and consequently, 50-m sprint time (with 0- to 20-m and 20- to50-m split time evaluation) was assessed 5 minutes before (pre-CA) and in the seventh minute after the completion of each CA (4 sets of 40 m either: 10% body mass resisted [RST]; 105% maximum velocity assisted [AST] sprint; or 2 sets of each sprint as the CA [COMB]), as well as after 48 hours of recovery. Furthermore, another blood sample was taken 48 hours later, before the warm-up, to assess changes in creatine kinase activity. A significantly higher 20-m sprint time at post-CA ( p = 0.006; ES = 0.4) and post-48 ( p = 0.011; ES = 0.59) compared with pre-CA in the RST condition was found, whereas a significantly lower sprint time was reported in post-48 compared with post-CA ( p = 0.019; ES = 0.44) in the COMB condition. However, a significantly lower 30-m flying sprint time at post-CA ( p < 0.001; ES = 0.28) and at post-48 ( p = 0.014; ES = 0.22) compared with pre-CA in the RST condition was revealed. Moreover, a significantly lower 30-m flying sprint time at post-48 compared with the pre-CA ( p = 0.007; ES = 0.7 and p = 0.003; ES = 0.77) and with the post-CA ( p = 0.019; ES = 0.61 and p = 0.009; ES = 0.68) in the AST condition and COMB was reported. Furthermore, a significantly lower 50-m sprint time at post-48 compared with pre-CA ( p = 0.015; ES = 0.51 and p = 0.011; ES = 0.64) and with post-CA ( p = 0.005; ES = 0.46 and p = 0.001; ES = 0.55) in the AST and COMB condition were found. The creatine kinase activity at post-48 during AST was significantly lower than during RST ( p = 0.028; ES = 0.73) and COMB ( p = 0.028; ES = 1.48). No significant changes were found for biceps femoris stiffness ( p = 0.085; η 2 = 0.199). The COMB and AST contributed to the improvement of the 50-m sprint time 48 hours after activation, which may be a good precompetition approach. However, during training sessions aiming to induce an acute PAPE effect and improve the 30-m flying sprint time, the best solution might be to use low-volume-resisted sprints.

Reactive Strength Index, Rate of Torque Development, and Performance in Well-Trained Weightlifters: A Pilot Study

The purpose of this study was to investigate the correlation between the reactive strength index (RSI) using the drop jump (DJ) and the isometric rate of torque development (RTD) with weightlifting performance in national-level weightlifters. Seven male weightlifters (age: 28.3 ± 5.7 years, body mass: 80.5 ± 6.7 kg, body height: 1.73 ± 0.07 m) participated in this study. Measurements were performed 2 weeks prior to the national championship and included the countermovement jump (CMJ), the squat jump (SJ), the DJ from three different drop heights (20, 30, and 40 cm), and the isometric peak torque (IPT) and RTD. Performance in CMJ and SJ was significantly correlated with weightlifting performance (r ranging from 0.756 to 0.892). Significant correlations were found between weightlifting performance with DJ contact time (r ranging from -0.759 to -0.899) and RSI (r ranging from 0.790 to 0.922). Moreover, the best RSI was significantly correlated with the snatch (r = 0.921, p = 0.003) and total performance (r = 0.832, p = 0.020). Small to very large correlations were found between IPT and RTD with weightlifting performance (r ranging from 0.254 to 0.796). These results suggest that RSI and contact time variables from DJ may predict weightlifting performance in well-trained weightlifters. Additionally, IPT and RTD may provide useful insights into the neuromuscular fitness condition of the weightlifter.

Does Moderate-Load Priming Activity Influence Maximal Upper-Body Performance and Perceptual State?

ABSTRACT

Harrison, PW, Kelly, VG, Jenkins, DG, McGuigan, MR, Holmberg, PM, and James, LP. Does moderate-load priming activity influence maximal upper-body performance and perceptual state?. J Strength Cond Res 37(11): e581-e587, 2023-The results of previous research indicate that resistance exercise "priming" may improve strength-power measures within 48 hours after their completion. Although researchers have primarily examined performance responses after lower-body priming stimuli, investigations examining the effects of upper-body resistance priming exercises are presently limited. Therefore, the aim of this study was to examine upper-body pushing and pulling performance in addition to perceptual responses 3 and 27 hours after moderate-load (ML) upper-body resistance priming exercise. Fourteen resistance-trained men were assigned to complete ML priming (4 × 3 bench press and bench pull at 65% 1RM [repetition maximum]) and control (rest) protocols in a randomized and counterbalanced order. Peak velocity during the bench throw and bench pull tests involving different loads (25, 50, and 75% 1RM) showed no practical change at 3 and 27 hours after the priming session (p = 0.216-0.99, Cliff's d = -0.041 to 0.225). Small effect size increases in perceptual measures ("physical feeling," "physical performance," "aggression" [p = 0.400-0.553, Cliff's d = 0.183-0.201], and "muscular heaviness" [p = 0.178, Cliff's d = 0.231]) were found at 3 hours postpriming. A moderate practical increase was observed in perceived "physical feeling" compared with control (p = 0.385, Cliff's d = 0.349) in addition to small effect size increases in perceived "physical performance" and "aggression" (Cliff's d = 0.243-0.290) at 27 hours after priming activities. These results indicate that upper-body strength-power changes within 27 hours after ML upper-body resistance exercise priming are not practically meaningful.

Ballistic Exercise Versus Heavy Resistance Exercise Protocols: Which Resistance Priming Is More Effective for Improving Neuromuscular Performance on the Following Day?

ABSTRACT

Nishioka, T and Okada, J. Ballistic exercise versus heavy resistance exercise protocols: which resistance priming is more effective for improving neuromuscular performance on the following day? J Strength Cond Res 37(10): 1939-1946, 2023-This study aimed to determine whether ballistic exercise priming (BEP) or heavy resistance priming (HRP) is more effective for improving ballistic performance after 24 hours. Ten resistance-trained men performed BEP and HRP conditions 72-144 hours apart in a randomized and counterbalanced order. Jumping performance was assessed before and 24 hours after the BEP and HRP sessions using 0 and 40% one-repetition maximum (1RM) squat jump (SJ), 0 and 40% 1RM countermovement jump (CMJ), and drop jump (DJ) reactive strength index (RSI). Statistical significance was accepted at p ≤ 0.05. In the BEP condition, 0% 1RM CMJ height (+3.62%) as well as theoretical maximum velocity (+5.14%) and theoretical maximum power (+2.55%) obtained from CMJ 24 hours after the priming session were significantly greater than those at the baseline ( p ≤ 0.05), but 0% 1RM SJ height and DJ RSI ( p > 0.05) were not greater than those at the baseline. In the HRP condition, the jump performances were not improved ( p > 0.05). The percentage change in 0% 1RM CMJ height in the BEP condition was significantly greater than that seen in the HRP condition ( p = 0.015) but did not differ for 0% 1RM SJ height and DJ RSI ( p > 0.05). These results suggest that the BEP is more effective than HRP in improving CMJ performance after 24 hours. Therefore, practitioners should consider prescribing resistance priming using low-load ballistic exercises rather than high-load traditional exercises when planning to enhance athlete performance on the following day.

Time Course of Jump Recovery and Performance After Velocity-Based Priming and Concurrent Caffeine Intake

Purpose: Morning priming exercise and caffeine intake have been previously suggested as an effective strategy to increase within-day performance and readiness. However, the concurrent effect of both strategies is unknown. The present research aimed to map the within-day time course of recovery and performance of countermovement jump (CMJ) outcomes, kinetics, and strategy and readiness after priming alone and in combination with caffeine. Methods: Eleven participants performed a control, a priming exercise (Priming) and a priming with concurrent caffeine intake (PrimingCaf) in a double-blind randomized, crossover design. CMJ metrics were assessed before, post, and 2 h, 4 h, and 6 h after each condition while readiness was assessed at 6 h. Results: Perceived physical, mental performance capability and activation balance were higher at 6 h after Priming and PrimingCaf conditions. Immediate reductions in jump height (5.45 to 6.25%; p < .046), concentric peak velocity (2.40 to 2.59%; p < .041) and reactive strength index-modified (RSImod) (9.06 to 9.23% p < .051) after Priming and PrimingCaf were observed, being recovered at 2 h (p > .99). Concentric impulse was restored in PrimingCaf (p > .754; d = -0.03 to-0.08) despite lower concentric mean force/BM (p < .662; d = -0.18 to -0.26) as concentric duration was increased (p > .513; d = 0.15 to 0.21). Individual analysis revealed that some participants benefit from both strategies as they showed increases in jump height over the smallest worthwhile change while others did not. Conclusions: Psychological readiness was increased after both priming conditions at 6 h; however, it seems necessary to consider individual changes to achieve the positive effects of the priming or the priming in combination with caffeine on jumping outcomes.

Delayed Effect of Dry-Land Strength Training Sessions on Swimming Performance

The purpose of the study was to examine the effects of dry-land strength endurance (SE) and maximum strength (MS) sessions on next-day swimming performance. Eight swimmers (age: 18.6 ± 2.9 years) performed evening training sessions (19:00-19:40), including: (i) SE (2 × 15 - 20 repetitions, 50% of 1-RM), (ii) MS (2 × 5 repetitions, 90% of 1-RM), (iii) control (CON: no dry-land training). All sessions were followed by a 90-min swimming training (20:00-21:30). Medicine ball throw and countermovement jump, free countermovement jump and squat jump were evaluated before and after the dry-land training session and 12 h later, before a 100-m front crawl sprint (next day at 8:30 a.m.). Performance time, RPE, blood lactate and biomechanical variables in 100-m sprint were no different between conditions (time, MS: 64.70 ± 7.35, SE: 63.81 ± 7.29, CON: 64.52 ± 7.71 s, p > 0.05). Jump height was not changed before and after dry-land and before the 100-m sprint in all conditions (p > 0.05). Medicine ball throw was lower in MS compared to CON before the 100-m sprint (MS: 4.44 ± 1.11, vs. CON: 4.66 ± 1.21 m, p < 0.05). Upper-body but not lower- body muscle function may be affected by MS training. However, performance in a 100-m test is not affected by dry-land training performed 12 h earlier.

Effects of Loaded Plyometric Exercise on Post-Activation Performance Enhancement of Countermovement Jump in Sedentary Men

Purpose: Explosive performance is increased right after performing loaded resistance exercise, which is known as post-activation performance enhancement (PAPE). Method: We investigated the effects of a plyometric exercise (PLYO) consisting of five sets of six drop-jumps from a 52-cm platform with a load corresponding to 20% body mass on changes in countermovement jump (CMJ) height in sedentary young men. Eleven young nonresistance trained men (19.6 ± 1.8 y, 69 ± 9 kg, 1.76 ± 0.08 m) who showed more than 4% increase in CMJ height at 4 min after five back squats with five-repetition maximum load participated in the study. Their responses to the back squat exercise were examined before (baseline) and 15 minutes, 24 and 48 hours post-PLYO. Exercise-induced muscle damage markers (maximal voluntary contraction torque [MVC], and quadriceps muscle soreness) were assessed at baseline, 15 minutes, 24 and 48 hours following PLYO. Results: MVC torque decreased (p < .05) at 15 minutes post-PLYO (-15.1 ± 9.7%) but returned to the baseline at 24 hours post-PLYO. Muscle soreness developed (p < .05) at 48 hours (21.0 ± 20.3 mm) after PLYO, indicating minor muscle damage. CMJ height increased (p < .05) after the five squats at baseline (7.6 ± 3.8%) indicating PAPE, but no such increase was found at 15 minutes, 24 and 48 hours after PLYO. However, CMJ height before the squat exercise was greater (p < .05) at 24 (5.9 ± 7.0%) and 48 hours post-PLYO (9.1 ± 8.5%) than the baseline. Conclusions: These results showed that PAPE disappeared after PLYO that induced minor muscle damage, but CMJ height increased at 24-48 hours in the recovery from PLYO exhibiting a priming effect.

Effects of Resistance Priming Exercise on Within-day Jumping Performance and its Relationship with Strength Level

This study aimed to identify the effects of same-day resistance priming exercise on countermovement jump parameters and subjective readiness, and to identify whether baseline strength level influenced these outcomes. Fourteen participants performed two separate conditions (Priming [2 sets high-load parallel squats with a 20% velocity loss cut-off] and Control) in a randomized, counterbalanced crossover design. Countermovement jump was assessed at pre, post and 6 h while readiness was assessed at pre and at 6 h only. All countermovement jump force-time metrics were similar between conditions (p>0.05), but different individual responses were noted 6 h after priming. Jump height was increased for 4/14, decreased for another 4/14, and maintained for 6/14 participants at 6 h. Higher perceived physical performance capability (p<0.001) and activation balance (p=0.005) were observed after priming only. Positive relationships were observed between strength and the percentage change in jump height (r=0.47-0.50; p=0.033-0.042), concentric peak velocity (r=0.48-0.51; p=0.030-0.041) and impulse (r=0.47; p=0.030-0.045) at post and 6 h after priming exercise. These findings suggest that velocity-based high-load low-volume priming exercise has potential to positively impact jump performance and subjective readiness later that day in certain individuals. Participant absolute strength level may influence this response but should be confirmed in subsequent studies.

Influence of an Acute Exposure to a Moderate Real Altitude on Motoneuron Pool Excitability and Jumping Performance

The aim of the study was to test whether ascending to a moderate real altitude affects motoneuron pool excitability at rest, as expressed by a change in the H-reflex amplitude, and also to elucidate whether a possible alteration in the motoneuron pool excitability could be reflected in the execution of lower-body concentric explosive (squat jump; SJ) and fast eccentric-concentric (drop jump; DJ) muscle actions. Fifteen participants performed four experimental sessions that consisted of the combination of two real altitude conditions [low altitude (low altitude, 690 m), high altitude (higher altitude, 2,320 m)] and two testing procedures (H-reflex and vertical jumps). Participants were tested on each testing day at 8, 11, 14 and 17 h. The only significant difference (p < 0.05) detected for the H-reflex was the higher H-reflex response (25.6%) obtained 15 min after arrival at altitude compared to baseline measurement. In terms of motor behavior, DJ height was the only variable that showed a significant interaction between altitude conditions (LA and HA) and time of measurement (8, 11, 14 and 17 h) as DJ height increased more during successive measurements at HA compared to LA. The only significant difference between the LA and HA conditions was observed for DJ height at 17 h which was higher for the HA condition (p = 0.04, ES = 0.41). Although an increased H-reflex response was detected after a brief (15–20 min) exposure to real altitude, the effect on motorneuron pool excitability could not be confirmed since no significant changes in the H-reflex were detected when comparing LA and HA. On the other hand, the positive effect of altitude on DJ performance was accentuated after 6 h of exposure.

Comparison between Dry-Land and Swimming Priming on 50 m Crawl Performance in Well-Trained Adolescent Swimmers

The purpose of the study was to investigate the effect of dry-land priming (DLP) versus swimming priming (SP) on the 50 m crawl performance of well-trained adolescent swimmers. Thirteen adolescent swimmers were randomly assigned to perform either a DLP or SP 24 h prior to a 50 m sprint crawl time-trial. Baseline measurements included a 50 m sprint crawl time-trial as a control (C) condition, the evaluation of body composition, countermovement jump (CMJ), isometric peak torque (IPT), and rate of torque development (RTD). Rating of perceived exertion (RPE) was obtained following the DLP and SP programs. Both DLP and SP significantly decreased the 50 m crawl time-trial, by −2.51 ± 2.43% and −2.59 ± 1.89% (p < 0.01), respectively, compared with the C time-trial. RPE was not different between DLP and SP (p = 0.919). CMJ performance remained unchanged after DLP and SP programs compared with the C trial (p > 0.05). The percentage decrease in the 50 m crawl after DLP was significantly correlated with the percentage decrease in the 50 m crawl following SP (r = 0.720, p = 0.006). CMJ power, lean body mass, IPT, and RTD were significantly correlated with 50 m crawl performance. These results suggest that both DLP and SP strategies, when applied 24 h prior to a 50 m crawl time-trial, may enhance performance in well-trained adolescent swimmers.

Influence of Strength Level on Performance Enhancement Using Resistance Priming

ABSTRACT

Nishioka, T and Okada, J. Influence of strength level on performance enhancement using resistance priming. J Strength Cond Res 36(1): 37-46, 2022-The current study aimed to investigate (a) whether resistance priming was effective in enhancing jump performance for both stronger and weaker individuals and (b) how resistance priming influences the lower-body force-velocity profile. A total of 20 resistance-trained men performed priming and control conditions 72-144 hours apart in a randomized and counterbalanced order. Jump performances (0 and 40% 1 repetition maximum [1RM] squat jump, 0 and 40% 1RM countermovement jump [CMJ] and drop jump) were assessed before and 24 hours after the priming session, and before and 24 hours after rest (control). Priming session-induced percentage change in 0% 1RM CMJ height was positively correlated with the individual's relative half squat 1RM (r = 0.612, p ≤ 0.05). Using the median split method, subjects were divided into stronger (relative half squat 1RM = 1.93-2.67 kg·kg-1) and weaker (relative half squat 1RM = 1.37-1.92 kg·kg-1) groups and subsequently analyzed. The stronger group showed specific improvement in 0% 1RM CMJ performance 24 hours after the priming session (p ≤ 0.05), whereas the weaker group showed no improvement in any of their jump performances. Moreover, the priming session enhanced the theoretical maximum velocity (p ≤ 0.05), but not the theoretical maximum force during CMJ in the stronger group; whereas none of the force-velocity profile variables were enhanced in the weaker group. These results suggest that stronger individuals are more likely to experience performance enhancement using resistance priming, which may be movement- and velocity-specific.

The Effects of a Five-Month Lockdown Due to COVID-19 on Physical Fitness Parameters in Adolescent Students: A Comparison between Cohorts

Background: This study examined the effects of a five-month lockdown due to COVID-19 pandemic on physical fitness parameters in urban adolescent male and female students. Methods: Two hundred and ninety-three male and female students (age: 15.8 ± 0.3 years) who attended the fourth grade of the same high school during the years 2016–2017 (first control group), 2018–2019 (second control group) and 2020–2021 (lockdown group) took part in the present study. Results: The percentage of overweight and obese students, according to body mass index, increased in males from 16.0% (2016–2017) and 14.6% (2018–2019), to 36.7% in 2020–2021 (p < 0.01), and in females from 8.6% (2016–2017) and 7.0% (2016–2017), to 25.6% in 2020–2021 (p < 0.01). Lower body fitness, as assessed by jumping, sprinting and agility tests, was impaired for both males and females after the lockdown compared with the 2016–2017 and 2018–2019 cohorts (vertical jumps: 10.4–15.1%; p < 0.01; d = 0.58–1.01, 30 m sprint: 3.7–4.9%; p < 0.01; d = 0.62–0.74; 505 agility test: from 6.1% to 9.4%; p < 0.01; d = 0.80–1.04). However, flexibility and performance in upper-body fitness tests (handgrip maximum isometric strength and medicine ball throws with different loads) was significantly reduced only in males after the lockdown (p < 0.05 to 0.01). Conclusions: These results suggest that a five-month lockdown negative influenced the physical fitness of adolescent students. Notably, greater reductions were observed in upper body strength, power and flexibility in males than in females. These results highlight the need to maintain strength, power and body mass during long periods of inactivity in adolescent populations.

Impact of Low Volume Velocity-Controlled vs. Repetition to Failure Resistance Training Session on Measures of Explosive Performance in a Team of Adolescents Basketball Players

This study examined the short-term effects (post 6 h and 24 h) of two equated (70% of 1 repetition maximum (1-RM)) low volume resistance exercise protocols: (i) velocity-controlled (VC) and (ii) repetition to failure (RTF) on upper and lower body performance in competitive adolescent male basketball players. Following a randomized, counterbalanced design, ten participants (age: 16 ± 0.5 years) completed either VC or RTF separated by 72 h. VC consisted of 4 sets of 5 explosive repetitions (≥90% of the maximum velocity). RTF involved 2 sets of 10-RM (with no velocity control). Measurements of 20-m sprint, countermovement jump (CMJ) and medicine ball toss (MBT) were collected before (baseline), post 6 h and 24 h after either VC or RTF. Increases of CMJ post 6 h (VC, +6.7%; RTF, +2.4%) and MBT post 24 h (VC, +4.6%; RTF, +4.2%) were observed after both VC and RTF. Only VC potentiated CMJ after 24 h (+2.0 ± 2.3%). No other changes or differences between protocols were observed. Performing a low volume exercise protocol, either VC or RTF, induced similar potentiation effects on the vertical jump (post 6 h) and medicine ball toss (post 24 h) in adolescent basketball players. Only the VC protocol was still effective to potentiate CMJ performance after 24 h.

The Effect of Resistance Exercise Priming in the Morning on Afternoon Sprint Cross-Country Skiing Performance

PURPOSE

We tested whether a single session of heavy-load resistance priming conducted in the morning improved double-poling (DP) performance in the afternoon.

METHODS

Eight national-level male cross-country skiers (mean [SD]: 23 [3] y, 184 [6] cm, 73 [7] kg, maximum oxygen consumption = 69 [6] mL·kg-1·min-1) carried out 2 days of afternoon performance tests. In the morning, 5 hours before tests, subjects were counterbalanced to either a session of 3 × 3 repetitions (approximately 85%-90% 1-repetition maximum) of squat and sitting pullover exercises or no exercise. The performance was evaluated in DP as time to exhaustion (TTE) (approximately 3 min) on a treadmill and 30-m indoor sprints before and after TTE (30-m DP pre/post). Furthermore, submaximal DP oxygen cost, countermovement jump, and isometric knee-extension force during electrical stimulation were conducted. Participants reported perceived readiness on test days.

RESULTS

Resistance exercise session versus no exercise did not differ for TTE (approximately 3 min above) (mean ± 95% confidence interval = 3.6% ± 6.0%; P = .29; effect size [ES], Cohen d = 0.27), 30-m DP pre (-0.56% ± 0.80%; P = .21; ES = 0.20), 30-m DP post (-0.18% ± 1.13%; P = .76; ES = 0.03), countermovement jump (-2.0% ± 2.8%; P = .21; ES = 0.12), DP oxygen cost (-0.13% ± 2.04%; P = .91; ES = 0.02), or perceived readiness (P ≥ .11). Electrical stimulation force was not different in contraction or relaxation time but revealed low-frequency fatigue in the afternoon for the resistance exercise session only (-12% [7%]; P = .01; ES = 1.3).

CONCLUSION

A single session of heavy-load, low-volume resistance exercise in the morning did not increase afternoon DP performance of short duration in high-level skiers. However, leg low-frequency fatigue after resistance priming, together with the presence of small positive effects in 2 out of 3 DP tests, may indicate that the preconditioning was too strenuous.

Time Course of Neuromuscular, Hormonal, and Perceptual Responses Following Moderate- and High-Load Resistance Priming Exercise

PURPOSE

The aim of this study was to map responses over 32 hours following high-load (HL) and moderate-load (ML) half-squat priming.

METHODS

Fifteen participants completed control, HL (87% 1RM), and ML (65% 1RM) activities in randomized, counterbalanced order. Countermovement jump (CMJ), squat jump (SJ), saliva testosterone, saliva cortisol, and perceptual measures were assessed before and 5 minutes, 8 hours, 24 hours, and 32 hours after each activity. Results are presented as percentage change from baseline and 95% confidence interval (CI). Cliff delta was used to determine threshold for group changes.

RESULTS

SJ height increased by 4.5% (CI = 2.2-6.8, Cliff delta = 0.20) 8 hours following HL. CMJ and SJ improved by 6.1% (CI = 2.1-7.8, Cliff delta = 0.27) and 6.5% (CI = 1.2-11.8, Cliff delta = 0.30), respectively, 32 hours after ML. No clear diurnal changes in CMJ or SJ occurred 8 hours following control; however, increases of 3.9% (CI = 2.9-9.2, Cliff delta = 0.26) and 4.5% (CI = 0.9-8.1, Cliff delta = 0.24), respectively, were observed after 32 hours. Although diurnal changes in saliva hormone concentration occurred (Cliff delta = 0.37-0.92), the influence of priming was unclear. Perceived "physical feeling" was greater 8 hours following HL (Cliff delta = 0.36) and 32 hours after ML and control (Cliff delta = 0.17-0.34).

CONCLUSIONS

HL priming in the morning may result in small improvements in jump output and psychophysiological state in the afternoon. Similar improvements were observed in the afternoon the day after ML priming.

Delayed potentiation effects on neuromuscular performance after optimal load and high load resistance priming sessions using velocity loss

Aim: (i) to compare the effects of two different low-volume resistance priming sessions, where the external load is modified on neuromuscular performance after 6 h of rest; and (ii) to identify the effects on psychological readiness in participants with resistance training experience. Methods: Eleven participants (Body mass: 77.0 ± 8.9 kg; Body height: 1.76 ± 0.08 m; Half squat repetition maximum: 139.8 ± 22.4 kg) performed the priming session under three experimental conditions in a randomized and cross-over design during the morning. The control (CON) condition: no resistance training, "optimal load" (OL) condition: two half-squat sets with a velocity loss of around 20% were performed with the "optimal load", and 80% of repetition maximum (80% RM) condition: 2 half-squat sets with a velocity loss of around 20% were performed with the 80% RM. Countermovement jump (CMJ), mean power with OL (MP_OL) and 80% RM (MP_80RM), and mean velocity with OL (MV_OL) and 80% RM (MV_80RM) were assessed six hours after the intervention. Subjective readiness was also recorded prior to resistance training and evaluation. Significance was set at p < 0.05. Results: CMJ was higher after the 80% RM intervention than CON (p < 0.001; Δ = 6.5% [3.4-9.5]). MP_OL and MV_OL seemed to be unaffected by both morning sessions. Higher MP_80RM (p = 0.044; Δ = 9.7% [4.0-15.6]; d = 0.24[0.10-0.37]) and MV_80RM (p = 0.004; Δ = 8.1% [3.2-13.3]; d = 0.32[0.13-0.52]) after 80% RM than after CON were observed. No effect was observed on psychological readiness. Conclusions: 80% RM priming session increased CMJ height and the capacity to generate power and velocity under a high-load condition without any effect on psychological readiness.

A strength-oriented exercise session required more recovery time than a power-oriented exercise session with equal work

The present randomized cross-over controlled study aimed to compare the rate of recovery from a strength-oriented exercise session vs. a power-oriented session with equal work. Sixteen strength-trained individuals conducted one strength-oriented session (five repetitions maximum (RM)) and one power-oriented session (50% of 5RM) in randomized order. Squat jump (SJ), countermovement jump (CMJ), 20-m sprint, and squat and bench press peak power and estimated 1RMs were combined with measures of rate of perceived exertion (RPE) and perceived recovery status (PRS), before, immediately after and 24 and 48 h after exercise. Both sessions induced trivial to moderate performance decrements in all variables. Small reductions in CMJ height were observed immediately after both the strength-oriented session (7 ± 6%) and power-oriented session (5 ± 5%). Between 24 and 48 h after both sessions CMJ and SJ heights and 20 m sprint were back to baseline. However, in contrast to the power-oriented session, recovery was not complete 48 h after the strength-oriented session, as indicated by greater impairments in CMJ eccentric and concentric peak forces, SJ rate of force development (RFD) and squat peak power. In agreement with the objective performance measurements, RPE and PRS ratings demonstrated that the strength-oriented session was experienced more strenuous than the power-oriented session. However, these subjective measurements agreed poorly with performance measurements at the individual level. In conclusion, we observed a larger degree of neuromuscular impairment and longer recovery times after a strength-oriented session than after a power-oriented session with equal total work, measured by both objective and subjective assessments. Nonetheless, most differences were small or trivial after either session. It appears necessary to combine several tests and within-test analyses (e.g., CMJ height, power and force) to reveal such differences. Objective and subjective assessments of fatigue and recovery cannot be used interchangeably; rather they should be combined to give a meaningful status for an individual in the days after a resistance exercise session.

The Effectiveness of Frequency-Based Resistance Training Protocols on Muscular Performance and Hypertrophy in Trained Males: A Critically Appraised Topic

Clinical Scenario: Manipulation of exercise variables in resistance training (RT) is an important component in the development of muscular strength, power, and hypertrophy. Currently, most research centers on untrained or recreationally trained subjects. This critically appraised topic focuses on studies that center on the well-trained subject with regard to frequency of training. Clinical Question: In well-trained male subjects, is there an association between RT frequency and the development of muscular strength and hypertrophy? Summary of Key Findings: Four studies met the inclusion criteria and were included for analysis. All studies showed that lower-frequency training could elicit muscular strength and hypertrophy increases. One study suggested that a higher frequency compared with a lower frequency may provide a slight benefit to hypertrophic development. One study reported a greater level of delayed onset muscle soreness with lower frequency training. The 4 studies demonstrate support for the clinical question. Clinical Bottom Line: Current evidence suggests that lower-frequency RT produces equal to greater improvements on muscular strength and hypertrophy in comparison to higher-frequency RT when volume is equated. The evidence is particularly convincing when lower-frequency RT is associated with a total-body training protocol in well-trained male subjects. Strength of Recommendation: There is moderate-to-strong evidence to suggest that lower-frequency RT, when volume is equated, will produce equal to greater improvements on muscular strength and hypertrophy in comparison to higher-frequency RT.

Resistance Priming to Enhance Neuromuscular Performance in Sport: Evidence, Potential Mechanisms and Directions for Future Research

Recent scientific evidence supports the use of a low-volume strength-power 'resistance priming' session prior to sporting competition in an effort to enhance neuromuscular performance. Though research evidence relating to this strategy is presently limited, it has been shown to be effective in improving various measures of neuromuscular performance within 48 h. Post-activation potentiation strategies have previously been shown to enhance strength-power performance within 20 min of completing maximal or near-maximal resistance exercise. Comparably, a delayed potentiation effect has been demonstrated following 'resistance priming' at various times between 1 and 48 h in upper- and lower-body performance measures. This may have significant implications for a range of athletes when preparing for competition. Various exercise protocols have been shown to improve upper- and lower-body neuromuscular performance measures in this period. In particular, high-intensity resistance exercise through high loading (≥ 85% 1 repetition maximum) or ballistic exercise at lower loads appears to be an effective stimulus for this strategy. Although current research has identified the benefits of resistance priming to some physical qualities, many questions remain over the application of this type of session, as well as the effects that it may have on a range of specific sporting activities. The aims of this brief review are to assess the current literature examining the acute effects (1-48 h) of resistance exercise on neuromuscular performance and discuss potential mechanisms of action as well as provide directions for future research.

Anthropometric and Motor Performance Variables Are Decisive Factors for The Selection of Junior National Female Volleyball Players

This study examined whether anthropometric and fitness tests might successfully predict selection of young female volleyball players for a junior national team. Sixty four female players (age: 14.4 ± 0.5 y, body height: 1.76 ± 0.05 m, body mass: 63.9 ± 6.4 kg) underwent a selection procedure for the junior national team. Anthropometric data and speed and power test results were obtained and players were graded for their performance in a volleyball tournament. Selected players differed from the non-qualified in body height (3.4%; p = 0.001), standing reach height (2.6%; p = 0.001), the sum of skinfolds (15.4%; p = 0.035), body mass index (BMI; 7.1%; p = 0.005) and spike jump and reach (SJR) (2.5%; p = 0.001). Selected players were classified in the 99.2 ± 1.6 percentile in body height and in the 51.4 ± 20.6 percentile in the BMI, which were significantly different from those of the non-qualified players (95.4 ± 7.0 and 66.7 ± 18.6, p = 0.02 and p = 0.004, respectively). Stepwise discriminant analysis yielded a discriminant function (p < 0.001, η2 = 0.78) that was highly loaded by height, SJR and the BMI (r = 0.79, r = 0.74 and r = -0.53, respectively). Cross validation results showed that selection was correctly predicted in 15 out of the 20 selected players (predictive accuracy: 75.0%) and in 35 out of the 44 non-qualified players (predictive accuracy: 79.5%). In conclusion, body height, the BMI and SJR height successfully discriminated between selected and non-qualified elite young female junior national team volleyball players. The equal vertical jump, sprint and agility of selected and non-qualified players, highlight the importance of body height and the BMI for selection of elite junior female volleyball players.

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.

Upper and Lower Body Power Are Strong Predictors for Selection of Male Junior National Volleyball Team Players

Tsoukos, A, Drikos, S, Brown, LE, Sotiropoulos, K, Veligekas, P, and Bogdanis, GC. Upper and lower body power are strong predictors for selection of male junior National volleyball team players. J Strength Cond Res 33(10): 2760-2767, 2019-The purpose of this study was to determine whether a battery of anthropometric and lower and upper body strength and speed and power tests predicted selection of young volleyball players for a Junior National Team by expert coaches. Fifty-two male junior volleyball players (14.8 ± 0.5 years, height: 1.84 ± 0.05 m, body mass: 72.5 ± 7.1 kg) took part in a training camp and underwent a selection procedure by expert coaches' of the junior national team. Anthropometric data and fitness tests results were obtained and players were graded on a scale from 0 to 100 on the basis of their performance in a volleyball tournament. Selected players were superior in the majority of measured variables (p ≤ 0.017) and had higher grading scores compared with nonselected players (85.3 ± 4.1 vs. 70.5 ± 5.6, respectively, p < 0.01). The combination of spike jump and reach (SJR) test and 3-kg medicine ball throw (MB3) velocity explained 63.5% of the variance in expert coaches' grading (p < 0.001). A multivariate discriminant analysis yielded a significant discriminant function (Wilk's lambda = 0.55, χ = 29.324, p < 0.001, η = 0.82). Spike jump and reach and MB3 were the only variables that contributed to the discriminant function (standardized function coefficients: SJR = 0.68, MB3 = 0.67). Cross-validation results showed that selection was correctly predicted in 14 of the 16 selected players (predictive accuracy: 87.5%) and in 32 of the 36 nonselected players (predictive accuracy: 88.9%). The SJR and MB3 fitness tests can predict a large portion of the variance of expert coaches' grading and successfully discriminate elite young male volleyball players for selection vs. nonselection for a junior national team. This result is very important as performance testing during a selection process may be reduced to only 2 measurements.