Kinetic Analysis, Potentiation, and Fatigue During Vertical and Horizontal Plyometric Training: An In-Depth Investigation Into Session Volume.

Despite previous support for plyometric training, optimal dosing strategies remain unclear. PURPOSE: To investigate vertical and horizontal jump kinetic performance following a low-volume plyometric stimulus with progressively increased session jump volume. METHODS: Sixteen academy rugby players (20.0 [2.0] y; 103.0 [17.6] kg; 184.3 [5.5] cm) volunteered for this study. Vertical and horizontal jump sessions were conducted 1 week apart and consisted of a 40-jump low-volume plyometric stimulus using 4 exercises, after which volume was progressively increased to 200 jumps, using countermovement jump (CMJ) for vertical sessions and horizontal broad jump (HBJ) for horizontal sessions. Jump performance was assessed via force-plate analysis at baseline (PRE-0), following the low-volume plyometric stimulus (P-40), and every subsequent 10 jumps until the end of the session (P-50, P-60, P-70, ... P-200). RESULTS: The low-volume stimulus was effective in potentiating HBJ (2% to 5%) but not CMJ (0% to -7%) performance (P < .001). The HBJ performance enhancements were maintained throughout the entire high-volume session, while CMJ realized small but significant decrements (-5% to -7%) in jump height P-50 to P-80 before recovering to presession values. Moreover, increases in eccentric impulse (5% to 24%; P < .001) in both sessions were associated with decreased or maintained concentric impulse, indicating a breakdown in performance-augmenting mechanisms and less effective power transfer concentrically after moderate volumes. CONCLUSION: Practitioners should consider kinetic differences between HBJ and CMJ with increasing volume to better inform and understand session dosing strategies.

Effect of Small and Large Energy Surpluses on Strength, Muscle, and Skinfold Thickness in Resistance-Trained Individuals: A Parallel Groups Design.

BACKGROUND: Many perform resistance training (RT) to increase muscle mass and strength. Energy surpluses are advised to support such gains; however, if too large, could cause unnecessary fat gain. We randomized 21 trained lifters performing RT 3 d/wk for eight weeks into maintenance energy (MAIN), moderate (5% [MOD]), and high (15% [HIGH]) energy surplus groups to determine if skinfold thicknesses (ST), squat and bench one-repetition maximum (1-RM), or biceps brachii, triceps brachii, or quadriceps muscle thicknesses (MT) differed by group. COVID-19 reduced our sample, leaving 17 completers. Thus, in addition to Bayesian ANCOVA comparisons, we analyzed changes in body mass (BM) with ST, 1-RM, and MT changes via regression. We reported Bayes factors (BF10) indicating odds ratios of the relative likelihood of hypotheses (e.g., BF10 = 2 indicates the hypothesis is twice as likely as another) and coefficients of determination (R2) for regressions. RESULTS: ANCOVAs provided no evidence supporting the group model for MT or squat 1-RM. However, moderate (BF10 = 9.9) and strong evidence (BF10 = 14.5) indicated HIGH increased bench 1-RM more than MOD and MAIN, respectively. Further, there was moderate evidence (BF10 = 4.2) HIGH increased ST more than MAIN and weak evidence (BF10 = 2.4) MOD increased ST more than MAIN. Regression provided strong evidence that BM change predicts ST change (BF10 = 14.3, R2 = 0.49) and weak evidence predicting biceps brachii MT change (BF10 = 1.4, R2 = 0.24). CONCLUSIONS: While some group-based differences were found, our larger N regression provides the most generalizable evidence. Therefore, we conclude faster rates of BM gain (and by proxy larger surpluses) primarily increase rates of fat gain rather than augmenting 1-RM or MT. However, biceps brachii, the muscle which received the greatest stimulus in this study, may have been positively impacted by greater BM gain, albeit slightly. Our findings are limited to the confines of this study, where a group of lifters with mixed training experience performed moderate volumes 3 d/wk for 8 weeks. Thus, future work is needed to evaluate the relationship between BM gains, increases in ST and RT adaptations in other contexts.

Range of Motion Predicts Performance in National-Level New Zealand Male Powerlifters.

ABSTRACT: Spence, AJ, Helms, ER, Sousa, CA, and McGuigan, MR. Range of motion predicts performance in National-level New Zealand male powerlifters. J Strength Cond Res 37(1): 123-128, 2023-Previous research established that male powerlifters have less range of motion (ROM) in several movements about the shoulder and hip compared with sedentary male subjects. It is unclear if these differences in ROM are related to strength, training type, and years of training experience or if individuals with less ROM have a better propensity to gain strength. The purpose of this study was to compare strength and ROM in male powerlifters and recreationally strength-trained male subjects and to determine if ROM would be an effective predictor of strength in these groups. Twelve powerlifters and 12 recreationally strength-trained control subjects completed 1 repetition maximum (1RM) squat and bench press testing. In a subsequent session, active ROM was measured, and velocity data were collected during submaximal squat repetitions. There was no significant difference (p > 0.05) between the groups for age, height, body mass, training experience, and training frequency. Powerlifters had significantly greater (p ≤ 0.05) training duration and absolute squat and bench press 1RM. Powerlifters had significantly less shoulder extension and horizontal abduction, and hip flexion, extension, and adduction than recreationally strength-trained men. Significant negative relationships were found between 2-lift Wilks score (body mass relative strength) and shoulder extension and horizontal abduction, as well as hip flexion and extension. In powerlifters, significant negative relationships were found between competition Wilks score, shoulder extension, and hip flexion. Because these relationships correspond to the bottom position of the squat and bench press, it may be best to ensure that shoulder extension and hip flexion remain sufficient to achieve competition depth.

Stretching Practices of International Powerlifting Federation Unequipped Powerlifters.

ABSTRACT: Spence, A-J, Helms, ER, and McGuigan, MR. Stretching practices of International Powerlifting Federation unequipped powerlifters. J Strength Cond Res 36(12): 3456-3461, 2022-Stretching practices in powerlifters. The purpose of this study was to provide insight into the stretching practices of competitive powerlifters. Powerlifters ( n = 319) from 51 countries completed a self-reported online survey on stretching practices. Subjects had (mean ± SD , median, and interquartile range) 7.7 ± 6.1, 6, and 6 years of general resisting training, 4.4 ± 4.5, 3, and 3 years of strength specific training, and been competing in powerlifting for 3.0 ± 3.7, 2, and 2 years with the average Wilks score being 366.4 ± 52.2, 365, and 60. Analysis by sex and competitive standard was conducted. More than 50% (52.4%) of subjects ( n = 167) reported stretching; of those, 84.4% performed static stretches, and 90.4% performed dynamic stretches. Stretching was performed before resistance training by 77.8%, after resistance training by 43.7%, and 53.9% stretched independent of resistance training. Powerlifters who performed static stretches before training did an average of 6.72 ± 10.31, 5, and 8 repetitions per stretch and held those stretches for an average of 30.8 ± 31.4, 20, and 15 seconds; 90.1% also performed dynamic stretches. Powerlifters who performed static stretches after or independent of training did an average of 4.1 ± 4.2, 2, and 9 repetitions per stretch and held those stretches for an average of 42.9 ± 30.8, 30, and 33 seconds. The majority of powerlifters (66.9%) programmed stretching themselves, whereas only 10.2% had stretching programmed by their coach. These data will inform athletes and coaches about the prevalence and characteristics of current stretching practices in powerlifters.

Range of Motion Is Not Reduced in National-Level New Zealand Female Powerlifters.

ABSTRACT: Spence, A-J, Helms, ER, and McGuigan, MR. Range of motion is not reduced in national-level New Zealand female powerlifters. J Strength Cond Res 35(10): 2737-2741, 2021-Some research suggests male powerlifters have less range of motion (ROM) in several directions about the shoulder and hip compared with sedentary men. In addition, those differences may be more pronounced in groups with higher strength levels and more years of experience. However, there is no information on ROM in female powerlifters. The purpose of this study was to evaluate single-joint ROM in competitive female powerlifters and determine whether single-joint ROM would be an effective predictor of strength in this population. Twelve female powerlifters and 12 female recreationally trained age-matched controls attended one testing session. Subjects reported their years of training experience, frequency, and average duration of training sessions. Active ROM measurements were collected at the shoulder, hip, and knee, using goniometry. There was no significant difference (p > 0.05) between groups for age, height, body mass, training experience, and training frequency. Powerlifters reported significantly greater (p ≤ 0.05) training durations than recreationally trained women. Powerlifters had significantly greater shoulder horizontal abduction on the right side (p = 0.022, g = 0.97), but no other ranges were significantly different between groups, and no ranges were significantly related to strength. Powerlifting does not seem to affect shoulder, hip, or knee ROM differently than recreational resistance training in women. Single-joint ROM was not an effective predictor of strength in female powerlifters.

The Addition of Transcutaneous Electrical Nerve Stimulation with Roller Massage Alone or in Combination Did Not Increase Pain Tolerance or Range of Motion.

Roller massage (RM) can be painful and induce muscle activity during application. Acute increases in pain pressure threshold (PPT) and range of motion (ROM) have been previously reported following RM. It is unclear whether the RM-induced increases in PPT and ROM can be attributed to changes in neural or muscle responses. To help determine if neural pain pathways are affected by roller massage, transcutaneous electrical nerve stimulation (TENS) was utilized as a form of electroanalgesia during RM with PPT and ROM tested on the affected and contralateral quadriceps. The purpose of this study was to evaluate in both quadriceps, the effect of brief intense TENS on PPT and ROM following unilateral RM of the quadriceps. A randomized within subjects' design was used to examine local and non-local effects of TENS and roller massage versus a control condition (rolling without TENS application). Four 30s bouts of roller massage of the dominant quadriceps were implemented with 30s of rest. The researcher applied the RM using a constant pressure device with approximately 70% of the maximum tolerable load. Perceived pain was monitored using a visual analog scale (VAS) during RM. Ipsilateral and contralateral quadriceps ROM and PPT were measured immediately following RM. Significant main effects for time showed increased PPT and ROM in both the treated and contralateral quadriceps, with no significant main effects for intervention or interactions for intervention and time. Moderate to large effect sizes and minimal clinically important differences (MCID) were detected when comparing baseline to pre- and post-tests respectively. VAS scores were significantly (main effect for intervention) and near significantly (interactions) reduced with MCID when TENS was applied during rolling. The addition of TENS to rolling did not increase PPT or ROM in the affected or contralateral quadriceps, likely due to a repeated testing effect.

Roller massage decreases spinal excitability to the soleus.

Roller massage (RM) interventions have shown acute increases in range of motion (ROM) and pain pressure threshold (PPT). It is unclear whether the RM-induced increases can be attributed to changes in neural or muscle responses. The purpose of this study was to evaluate the effect of altered afferent input via application of RM on spinal excitability, as measured with the Hoffmann (H-) reflex. A randomized within-subjects design was used. Three 30-s bouts of RM were implemented on a rested, nonexercised, injury-free muscle with 30 s of rest between bouts. The researcher applied RM to the plantar flexors at three intensities of pain: high, moderate, and sham. Measures included normalized M-wave and H-reflex peak-to-peak amplitudes before, during, and up to 3 min postintervention. M-wave and H-reflex measures were highly reliable. RM resulted in significant decreases in soleus H-reflex amplitudes. High-intensity, moderate-intensity, and sham conditions decreased soleus H-reflex amplitudes by 58%, 43%, and 19%, respectively. H-reflexes induced with high-intensity rolling discomfort or pain were significantly lower than moderate and sham conditions. The effects were transient in nature, with an immediate return to baseline following RM. This is the first evidence of RM-induced modulation of spinal excitability. The intensity-dependent response observed indicates that rolling pressure or pain perception may play a role in modulation of the inhibition. Roller massage-induced neural modulation of spinal excitability may explain previously reported increases in ROM and PPT. NEW & NOTEWORTHY Recent evidence indicates that the benefits of foam rolling and roller massage are primarily accrued through neural mechanisms. The present study attempts to determine the neuromuscular response to roller massage interventions. We provide strong evidence of roller massage-induced neural modulation of spinal excitability to the soleus. It is plausible that reflex inhibition may explain subsequent increases in pain pressure threshold.

Phase- and Workload-Dependent Changes in Corticospinal Excitability to the Biceps and Triceps Brachii during Arm Cycling.

This is the first study to examine corticospinal excitability (CSE) to antagonistic muscle groups during arm cycling. Transcranial magnetic stimulation (TMS) of the motor cortex and transmastoid electrical stimulation (TMES) of the corticospinal tract were used to assess changes in supraspinal and spinal excitability, respectively. TMS induced motor evoked potentials (MEPs) and TMES induced cervicomedullary evoked potentials (CMEPs) were recorded from the biceps and triceps brachii at two positions, mid-elbow flexion and extension, while cycling at 5% and 15% of peak power output. While phase-dependent modulation of MEP and CMEP amplitudes occurred in the biceps brachii, there was no difference between flexion and extension for MEP amplitudes in the triceps brachii and CMEP amplitudes were higher during flexion than extension. Furthermore, MEP amplitudes in both biceps and triceps brachii increased with increased workload. CMEP amplitudes increased with higher workloads in the triceps brachii, but not biceps brachii, though the pattern of change in CMEPs was similar to MEPs. Differences between changes in CSE between the biceps and triceps brachii suggest that these antagonistic muscles may be under different neural control during arm cycling. Putative mechanisms are discussed.