Improved power clean performance with the hook-grip is not due to altered force-time or horizontal bar-path characteristics.

he underlying biomechanical benefits of hook-grip (HG) over conventional closed-grip (CG) remain unclear. This study compared bar-path kinematics and force-time variables of the power clean (PC) performed with HG or CG. We also aimed to compared kinetic changes measured by force platform versus linear position transducer (LPT). Eleven well-trained men volunteered. Following a familiarisation session, HG, and CG 1RM conditions, were randomly completed seven days apart. System kinetics and barbell kinematics were recorded via synchronized force platform+LPT system and two-dimensional motion-capture. Statistical parametric mapping (SPM), analysis of variance, and standardised differences were utilised. The SPM cut-offs were determined via novel combination of force and displacement. No between-condition differences in normalised force-time variables of the pull or catch were detected. The first and second pull duration was similar between conditions (ES = 0.04-0.38). Conversely, catch and total PC durations were shorter at 80-95% (ES = 0.26-0.75), with the weightless phase more prolonged at 95% and 100% (ES = 0.54-0.76) with HG compared to CG. Improved timing of the turnover and catch phases appears to be the primary difference between HG and CG performance. Thus, grip type is possibly irrelevant to non-weightlifting athletes when performing submaximal catch-less derivatives..

Variability of Multiangle Isometric Force-Time Characteristics in Trained Men.

ABSTRACT: Oranchuk, DJ, Storey, AG, Nelson, AR, Neville, JG, and Cronin, JB. Variability of multiangle isometric force-time characteristics in trained men. J Strength Cond Res 36(1): 284-288, 2022-Measurements of isometric force, rate of force development (RFD), and impulse are widely reported. However, little is known about the variability and reliability of these measurements at multiple angles, over repeated testing occasions in a homogenous, resistance-trained population. Thus, understanding the intersession variability of multiangle isometric force-time characteristics provides the purpose of this article. Three sessions of isometric knee extensions at 40°, 70°, and 100° of flexion were performed by 26 subjects across 51 limbs. All assessments were repeated on 3 occasions separated by 5-8 days. Variability was qualified by doubling the typical error of measurement (TEM), with thresholds of 0.2-0.6 (small), 0.6-1.2 (moderate), 1.2-2.0 (large), 2.0-4.0 (very large), and >4.0 (extremely large). In addition, variability was deemed large when the intraclass correlation coefficient (ICC) was <0.67 and coefficient of variation (CV) >10%; moderate when ICC >0.67 or CV <10% (but not both); and small when both ICC >0.67 and CV <10%. Small to moderate between-session variability (ICC = 0.68-0.95, CV = 5.2-18.7%, TEM = 0.24-0.49) was associated with isometric peak force, regardless of angle. Moderate to large variability was seen in early-stage (0-50 ms) RFD and impulse (ICC = 0.60-0.80, CV = 22.4-63.1%, TEM = 0.62-0.74). Impulse and RFD at 0-100 ms, 0-200 ms, and 100-200 ms were moderately variable (ICC = 0.71-0.89, CV = 11.8-42.1%, TEM = 0.38-0.60) at all joint angles. Isometric peak force and late-stage isometric RFD and impulse measurements were found to have low intersession variability regardless of joint angle. However, practitioners need to exercise caution when making inferences about early-stage RFD and impulse measures due to moderate-large variability.

Short-term neuromuscular, morphological, and architectural responses to eccentric quasi-isometric muscle actions.

PURPOSE: Eccentric quasi-isometric (EQI) contractions have been proposed as a novel training method for safely exposing the musculotendinous system to a large mechanical load/impulse, with few repetitions. However, understanding of this contraction type is rudimentary. We aimed to compare the acute effects of a single session of isotonic EQIs with isokinetic eccentric (ECC) contractions. METHODS: Fifteen well-trained men performed a session of impulse-equated EQI and ECC knee extensions, with each limb randomly allocated to one contraction type. Immediately PRE, POST, 24/48/72 h, and 7 days post-exercise, regional soreness, quadriceps swelling, architecture, and echo intensity were evaluated. Peak concentric and isometric torque, rate of torque development (RTD), and angle-specific impulse were evaluated at each time point. RESULTS: There were substantial differences in the number of contractions (ECC: 100.8 ± 54; EQI: 3.85 ± 1.1) and peak torque (mean: ECC: 215 ± 54 Nm; EQI: 179 ± 28.5 Nm). Both conditions elicited similar responses in 21/53 evaluated variables. EQIs resulted in greater vastus intermedius swelling (7.1-8.8%, ES = 0.20-0.29), whereas ECC resulted in greater soreness at the distal and middle vastus lateralis and distal rectus femoris (16.5-30.4%, ES = 0.32-0.54) and larger echogenicity increases at the distal rectus femoris and lateral vastus intermedius (11.9-15.1%, ES = 0.26--0.54). Furthermore, ECC led to larger reductions in concentric (8.3-19.7%, ES = 0.45-0.62) and isometric (6.3-32.3%, ES = 0.18-0.70) torque and RTD at medium-long muscle lengths. CONCLUSION: A single session of EQIs resulted in less soreness and smaller reductions in peak torque and RTD versus impulse-equated ECC contractions, yet morphological shifts were largely similar. Long-term morphological, architectural, and neuromuscular adaptations to EQI training requires investigation.

Implementation and Efficacy of Plyometric Training: Bridging the Gap Between Practice and Research.

ABSTRACT: Watkins, CM, Storey, A, McGuigan, M, and Gill, ND. Implementation and efficacy of plyometric training: Bridging the gap between practice and research. J Strength Cond Res 35(5): 1244-1255, 2021-Plyometric training is an effective method for improving speed and acceleration. However, a gap seems to exist between research recommendations and practitioner's actual programs. Some reports suggest as many as 400 jumps per session, while anecdotally some strength and conditioning coaches are using as few as 15-40 jumps even with elite athletes. Thus, the purposes of this study were to obtain a clearer understanding of the practitioner's perspective on plyometric training strategies as compared to literary recommendations and to compare any trends across competition level or sport categories. An integrative mixed-methods model was used. Globally, 61 strength and conditioning practitioners completed an anonymous online survey, containing 5 sections: 1. Sport and coaching background information, 2. Plyometric training focus, 3. Periodization strategy, 4. Plyometric program details, and 5. Efficacy of plyometrics for sport performance. Questions included yes/no, multiple choice, Likert scale, percentage-based, and open-ended questions. The majority (70.5%) of respondents reported regularly implementing plyometric training and overwhelmingly (96.7%) reported positive athlete feedback surrounding its perceived efficacy. Findings confirmed that many practitioners regularly use significantly lower session volumes than previous literary recommendations (p < 0.05). In addition, significant differences were noted in many program details across competition level and sport category including volume periodization, exercise choice, and plyometric intensity. Practitioners may want to reflect on these reported group differences when building training programs best suited for their athletes. Meanwhile, future research should consider these reported perspectives when formulating interventions in attempts of bridging the gap between practice and theory.

Horizontal Force-Velocity-Power Profiling of Rugby Players: A Cross-Sectional Analysis of Competition-Level and Position-Specific Movement Demands.

ABSTRACT: Watkins, CM, Storey, A, McGuigan, MR, Downes, P, and Gill, ND. Horizontal force-velocity-power profiling of rugby players: A cross-sectional analysis of competition-level and position-specific movement demands. J Strength Cond Res 35(6): 1576-1585, 2021-Speed and acceleration are crucial to competitive success in all levels of rugby union. However, positional demands affect an athlete's expression of force and velocity during the match. This study investigated maximal sprint performance and horizontal force-velocity (FV) profiles in 176 rugby union players participating in amateur club, professional, and international competitions. Rugby players were divided into 5 positional groups: tight-5 forwards (n = 63), loose forwards (n = 35), inside backs (n = 29), midbacks (n = 22), and outside (n = 27) backs. Sprint performance was averaged across 2 trials of a maximal 30-m sprint, separated by a 3-minute rest. The results demonstrated differences in sprint performance and FV profile characteristics across competitions and positional groups. Specifically, both international and professional players possessed significantly faster split times and superior FV profiles than club players (p < 0.01; effect size [ES]: 0.22-1.42). International players were significantly faster across 0-10 m than professional players (p = 0.03; ES: 0.44-0.47), whereas professional players had faster 10-20 m times (p = 0.03; ES: 0.37-0.41) and a more force-dominant profile (p < 0.01; ES: 0.71-1.00). Across positions, split times decreased and maximal velocity characteristics increased in proportion with increasing positional number, with outside backs being the fastest (ES: 0.38-2.22). On the other hand, both forwards groups had more force-dominant profiles and average sprint momentum across all distances than all backs positions. Interestingly, loose forwards had a more forceful profile and slower 10-, 20-, and 30-m split times but similar maximal velocity characteristics to inside backs, highlighting unique positional demands and physical attributes.

The Effect of Low-Volume Preseason Plyometric Training on Force-Velocity Profiles in Semiprofessional Rugby Union Players.

ABSTRACT: Watkins, CM, Gill, ND, Maunder, E, Downes, P, Young, JD, McGuigan, MR, and Storey, AG. The effect of low-volume preseason plyometric training on force-velocity profiles in semiprofessional rugby union players. J Strength Cond Res 35(3): 604-615, 2021-Rugby union is a physically demanding and complex team sport requiring athletes across all positions to express speed and acceleration. Plyometrics can effectively improve speed profiles by enhancing both force- and velocity-(FV) characteristics; however, the optimal dose and exercise direction for trained athletes is still relatively unknown. Therefore, the aim of this investigation was to determine the efficacy of a low-dose, directionally specific plyometric training program for improving speed profiles in semiprofessional rugby players. Players were randomly allocated to one of 2 plyometric training groups that performed low-volume (40-60 ground contacts per session) plyometrics twice weekly, or a control group that did not participate in any plyometric training. The 2 training groups underwent reverse back-to-back three-week vertically and horizontally focused plyometric training programs, with a 12-day washout. Body composition, aerobic capacity, and sprint performance (10-, 20-, 30-m split time, horizontal FV profile) were measured. During the intervention, HV-1 (horizontal/vertical training group 1) improved sprint performance (n = 12; ∆30 m = -0.020 seconds; p = 0.038), VH-2 (vertical/horizontal training group 2) maintained sprint performance (n = 8; ∆30 m = +0.049 seconds; p = 0.377), and the control group progressively declined in sprint performance (n = 12; ∆30 m = +0.071; p = 0.019). In addition, vertical plyometrics may preferentially benefit secondary acceleration (∆10-20 m split time: -0.01 seconds; p = 0.03) and many force-oriented FV profile characteristics. Correlational analyses (r2 = -0.568 to 0.515) showed sprint improvements were hindered in athletes with lower initial aerobic fitness, suggesting accumulated fatigue may have limited the magnitude of adaptation. Therefore, including low-volume plyometric training may be beneficial for improving sprint profiles or attenuating decrements realized during periods of high-volume sport-specific training.

Isometric training and long-term adaptations: Effects of muscle length, intensity, and intent: A systematic review.

Isometric training is used in the rehabilitation and physical preparation of athletes, special populations, and the general public. However, little consensus exists regarding training guidelines for a variety of desired outcomes. Understanding the adaptive response to specific loading parameters would be of benefit to practitioners. The objective of this systematic review, therefore, was to detail the medium- to long-term adaptations of different types of isometric training on morphological, neurological, and performance variables. Exploration of the relevant subject matter was performed through MEDLINE, PubMed, SPORTDiscus, and CINAHL databases. English, full-text, peer-reviewed journal articles and unpublished doctoral dissertations investigating medium- to long-term (≥3 weeks) adaptations to isometric training in humans were identified. These studies were evaluated further for methodological quality. Twenty-six research outputs were reviewed. Isometric training at longer muscle lengths (0.86%-1.69%/week, ES = 0.03-0.09/week) produced greater muscular hypertrophy when compared to equal volumes of shorter muscle length training (0.08%-0.83%/week, ES = -0.003 to 0.07/week). Ballistic intent resulted in greater neuromuscular activation (1.04%-10.5%/week, ES = 0.02-0.31/week vs 1.64%-5.53%/week, ES = 0.03-0.20/week) and rapid force production (1.2%-13.4%/week, ES = 0.05-0.61/week vs 1.01%-8.13%/week, ES = 0.06-0.22/week). Substantial improvements in muscular hypertrophy and maximal force production were reported regardless of training intensity. High-intensity (≥70%) contractions are required for improving tendon structure and function. Additionally, long muscle length training results in greater transference to dynamic performance. Despite relatively few studies meeting the inclusion criteria, this review provides practitioners with insight into which isometric training variables (eg, joint angle, intensity, intent) to manipulate to achieve desired morphological and neuromuscular adaptations.

Scientific Basis for Eccentric Quasi-Isometric Resistance Training: A Narrative Review.

Oranchuk, DJ, Storey, AG, Nelson, AR, and Cronin, JB. The scientific basis for eccentric quasi-isometric resistance training: A narrative review. J Strength Cond Res 33(10): 2846-2859, 2019-Eccentric quasi-isometric (EQI) resistance training involves holding a submaximal, yielding isometric contraction until fatigue causes muscle lengthening and then maximally resisting through a range of motion. Practitioners contend that EQI contractions are a powerful tool for the development of several physical qualities important to health and sports performance. In addition, several sports involve regular quasi-isometric contractions for optimal performance. Therefore, the primary objective of this review was to synthesize and critically analyze relevant biological, physiological, and biomechanical research and develop a rationale for the value of EQI training. In addition, this review offers potential practical applications and highlights future areas of research. Although there is a paucity of research investigating EQIs, the literature on responses to traditional contraction types is vast. Based on the relevant literature, EQIs may provide a practical means of increasing total volume, metabolite build-up, and hormonal signaling factors while safely enduring large quantities of mechanical tension with low levels of peak torque. Conversely, EQI contractions likely hold little neuromuscular specificity to high velocity or power movements. Therefore, EQI training seems to be effective for improving musculotendinous morphological and performance variables with low injury risk. Although speculative due to the limited specific literature, available evidence suggests a case for future experimentation.

The High-Bar and Low-Bar Back-Squats: A Biomechanical Analysis.

Glassbrook, DJ, Brown, SR, Helms, ER, Duncan, S, and Storey, AG. The high-bar and low-bar back-squats: a biomechanical analysis. J Strength Cond Res 33(7S): S1-S18, 2019-No previous study has compared the joint angle and ground reaction force (vertical force [Fv]) differences between the high-bar back-squat (HBBS) and low-bar back-squat (LBBS) above 90% 1 repetition maximum (1RM). Six male powerlifters (POW) (height: 179.2 ± 7.8 cm; mass: 87.1 ± 8.0 kg; age: 21-33 years) of international level, 6 male Olympic weightlifters (OLY) (height: 176.7 ± 7.7 cm; mass: 83.1 ± 13 kg; age: 22-30 years) of national level, and 6 recreationally trained male athletes (height: 181.9 ± 8.7 cm; mass: 87.9 ± 15.3 kg; age: 23-33 years) performed the LBBS, HBBS, and both LBBS and HBBS (respectively) up to and including 100% 1RM. Small to moderate (d = 0.2-0.5) effect size differences were observed between the POW and OLY in joint angles and Fv, although none were statistically significant. However, significant joint angle results were observed between the experienced POW/OLY and the recreationally trained group. Our findings suggest that practitioners seeking to place emphasis on the stronger hip musculature should consider the LBBS. Also, when the goal is to lift the greatest load possible, the LBBS may be preferable. Conversely, the HBBS is more suited to replicate movements that exhibit a more upright torso position, such as the snatch and clean, or to place more emphasis on the associated musculature of the knee joint.

Rating of Perceived Exertion as a Method of Volume Autoregulation Within a Periodized Program.

Helms, ER, Cross, MR, Brown, SR, Storey, A, Cronin, J, and Zourdos, MC. Rating of perceived exertion as a method of volume autoregulation within a periodized program. J Strength Cond Res 32(6): 1627-1636, 2018-The purpose of this investigation was to observe how a rating of perceived exertion (RPE)-based autoregulation strategy impacted volume performed by powerlifters. Twelve (26 ± 7 years, n = 9 men, n = 3 women) nationally qualified powerlifters performed the back squat, bench press, and deadlift 3x per week on nonconsecutive days in a session order of hypertrophy, power, and then strength; for 3 weeks. Each session subjects performed an initial top set for a prescribed number of repetitions at a target RPE. A second top set was performed if the RPE score was too low, then subsequent back-off sets at a reduced load were performed for the same number of repetitions. When the prescribed RPE was reached or exceeded, sets stopped; known as an "RPE stop." The percentage load reduction for back-off sets changed weekly: there were 2, 4, or 6% RPE stop reductions from the top set. The order in which RPE stop weeks were performed was counterbalanced among subjects. Weekly combined relative volume load (squat + bench press + deadlift), expressed as sets x repetitions x percentage 1-repetition maximum was different between weeks (p < 0.001): 2% = 74.6 ± 22.3; 4% = 88.4 ± 23.8; 6% = 114.4 ± 33.4. Combined weekly bench press volume (hypertrophy + power + strength) was significantly higher in accordance with load reduction magnitude (2% > 4% > 6%; p ≤ 0.05), combined squat volume was greater in 6 vs. 2% (p ≤ 0.05), and combined deadlift volume was greater in 6 vs. 2% and 4% (p ≤ 0.05). Therefore, it does seem that volume can be effectively autoregulated using RPE stops as a method to dictate number of sets performed.

Acute effects of heated resistance exercise in female and male power athletes.

PURPOSE: To determine the effects of heated resistance exercise on thermal strain, neuromuscular function and hormonal responses in power athletes. METHODS: Sixteen (n = 8 female; 8 male) highly trained power athletes completed a combined strength and power resistance exercise session in hot (HOT ~30 °C) and temperate (CON ~20 °C) conditions. Human growth hormone (hGH), cortisol and testosterone concentrations in plasma, peak power (counter-movement jump, CMJ) and peak force (isometric mid-thigh pull) were measured before and after each training session; thermoregulatory responses were monitored during training. RESULTS: Skin temperature, thermal sensation and thermal discomfort were higher in HOT compared with CON. Sweat rate was higher in HOT for males only. Compared with CON, HOT had trivial effects on core temperature and heart rate. During HOT, there was a possible increase in upper-body power (medicine ball throw) in females [3.4% (90% CL -1.5, 8.6)] and males [(3.3% (-0.1, 6.9)], while lower-body power (vertical jump) was enhanced in males only [3.2% (-0.4, 6.9)]. Following HOT, CMJ peak power [4.4% (2.5; 6.3)] and strength [8.2% (3.1, 13.6)] were enhanced in female athletes, compared with CON, while effects in males were unclear. Plasma hGH concentration increased in females [83% (18; 183)] and males [107% (-21; 444)] in HOT compared with CON, whereas differential changes occurred for cortisol and testosterone. CONCLUSION: Heated resistance exercise enhanced power and increased plasma hGH concentration in female and males power athletes. Further research is required to assess the ergogenic potential of resistance exercise in the heat.

A Review of the Biomechanical Differences Between the High-Bar and Low-Bar Back-Squat.

Glassbrook, DJ, Helms, ER, Brown, SR, and Storey, AG. A review of the biomechanical differences between the high-bar and low-bar back-squat. J Strength Cond Res 31(9): 2618-2634, 2017-The back-squat is a common exercise in strength and conditioning for a variety of sports. It is widely regarded as a fundamental movement to increase and measure lower-body and trunk function, as well as an effective injury rehabilitation exercise. There are typically 2 different bar positions used when performing the back-squat: the traditional "high-bar" back-squat (HBBS) and the "low-bar" back-squat (LBBS). Different movement strategies are used to ensure that the center of mass remains in the base of support for balance during the execution of these lifts. These movement strategies manifest as differences in (a) joint angles, (b) vertical ground reaction forces, and (c) the activity of key muscles. This review showed that the HBBS is characterized by greater knee flexion, lesser hip flexion, a more upright torso, and a deeper squat. The LBBS is characterized by greater hip flexion and, therefore, a greater forward lean. However, there are limited differences in vertical ground reaction forces between the HBBS and LBBS. The LBBS can also be characterized by a greater muscle activity of the erector spinae, adductors, and gluteal muscles, whereas the HBBS can be characterized by greater quadriceps muscle activity. Practitioners seeking to develop the posterior-chain hip musculature (i.e., gluteal, hamstring, and erector muscle groups) may seek to use the LBBS. In comparison, those seeking to replicate movements with a more upright torso and contribution from the quadriceps may rather seek to use the HBBS in training.

Self-Rated Accuracy of Rating of Perceived Exertion-Based Load Prescription in Powerlifters.

This study assessed male (n = 9) and female (n = 3) powerlifters' (18-49 years) ability to select loads using the repetitions in reserve-based rating of perceived exertion (RPE) scale for a single set for squat, bench press, and deadlift. Subjects trained 3× per week. For 3 weeks on nonconsecutive days in the weekly order of hypertrophy (8 repetitions at 8 RPE), power (2 repetitions at 8 RPE), and strength (3 repetitions at 9 RPE), using subject-selected loads intended to match the target RPE. Bench press and squat were performed every session and deadlift during strength and power only. Mean absolute RPE differences (|reported RPE-target RPE|) ranged from 0.22-0.44, with a mean of 0.33 ± 0.28 RPE. There were no significant RPE differences within lifts between sessions for squat or deadlift. However, bench press was closer to the target RPE for strength (0.15 ± 0.42 RPE) vs. power (-0.21 ± 0.35 RPE, p = 0.05). There were no significant differences within session between lifts for power and strength. However, bench press was closer (0.14 ± 0.44 RPE) to the target RPE than squat (-0.19 ± 0.21 RPE) during hypertrophy (p = 0.02). Squat power was closer to the target RPE in week 3 (0.08 ± 0.29 RPE) vs. 1 (-0.46 ± 0.69 RPE, p = 0.03). It seems that powerlifters can accurately select loads to reach a prescribed RPE. However, accuracy for 8-repetition sets at 8 RPE may be better for bench press compared with squat. Rating squat power-type training may take 3 weeks to reach peak accuracy. Finally, bench press RPE accuracy seems better closer rather than further from failure (i.e., 3-repetition 9 RPE sets vs. 2-repetition 8 RPE sets).

RPE and Velocity Relationships for the Back Squat, Bench Press, and Deadlift in Powerlifters.

Helms, ER, Storey, A, Cross, MR, Browm, SR, Lenetsky, S, Ramsay, H, Dillen, C, and Zourdos, MC. RPE and velocity relationships for the back squat, bench press, and deadlift in powerlifters. J Strength Cond Res 31(2): 292-297, 2017-The purpose of this study was to compare average concentric velocity (ACV) and rating of perceived exertion (RPE) based on repetitions in reserve on the squat, bench press, and deadlift. Fifteen powerlifters (3 women and 12 men, mean age 28.4 ± 8.5 years) worked up to a one repetition maximum (1RM) on each lift. Rating of perceived exertion was recorded on all sets, and the ACV was recorded for all sets performed at 80% of estimated 1RM and higher, up to 1RM. Rating of perceived exertion at 1RM on squat, bench press, and deadlift was 9.6 ± 0.5, 9.7 ± 0.4, and 9.6 ± 0.5, respectively and was not significantly different (p > 0.05). The ACV at 1RM on squat, bench press and deadlift was 0.23 ± 0.05, 0.10 ± 0.04, and 0.14 ± 0.05 m·second, respectively. Squat was faster than both bench press and deadlift (p > 0.001), and deadlift was faster than bench press (p = 0.05). Very strong relationships (r = 0.88-0.91) between percentage 1RM and RPE were observed on each lift. The ACV showed strong (r = -0.79 to -0.87) and very strong (r = -0.90 to 92) inverse relationships with RPE and percentage 1RM on each lift, respectively. We conclude that RPE may be a useful tool for prescribing intensity for squat, bench press, and deadlift in powerlifters, in addition to traditional methods such as percentage of 1RM. Despite high correlations between percentage 1RM and ACV, a "velocity load profile" should be developed to prescribe intensity on an individual basis with appropriate accuracy.

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.

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.

The effects of regional quadriceps architecture on angle-specific rapid force expression.

Evaluating anatomical contributions to performance can increase understanding of muscle mechanics and guide physical preparation. While the impact of anatomy on muscular performance is well studied, the effects of regional quadriceps architecture on rapid torque or force expression are less clear. Regional (proximal, middle, and distal) quadriceps (vastus lateralis, rectus femoris, and vastus intermedius) thickness (MT), pennation angle (PA), and fascicle length (FL) of 24 males (48 limbs) were assessed via ultrasonography. Participants performed maximal isometric knee extensions at 40°, 70°, and 100° of knee flexion to evaluate rate of force development from 0 to 200 ms (RFD0-200). Measurements were repeated on three occasions with the greatest RFD0-200 and mean muscle architecture measures used for analysis. Linear regression models predicting angle-specific RFD0-200 from regional anatomy provided adjusted correlations (√adjR2) with bootstrapped compatibility limits. Mid-rectus femoris MT (√adjR2 = 0.41-0.51) and proximal vastus lateralis FL (√adjR2 = 0.42-0.48) were the best single predictors of RFD0-200, and the only measures to reach precision with 99% compatibility limits. Small simple correlations were found across all regions and joint angles between RFD0-200 and vastus lateralis MT (√adjR2 = 0.28 ± 0.13; mean ± SD), vastus lateralis FL (√adjR2 = 0.33 ± 0.10), rectus femoris MT (√adjR2 = 0.38 ± 0.10), and lateral vastus intermedius MT (√adjR2 = 0.24 ± 0.10). Between-correlation comparisons are reported within the article. Researchers should measure mid-region rectus femoris MT and vastus lateralis FL to efficiently and robustly evaluate potential anatomical contributions to rapid knee extension force changes, with distal and proximal measurements providing little additional value. However, correlations were generally small to moderate, suggesting that neurological factors may be critical in rapid force expression.

Divergent muscle functional and architectural responses to two successive high intensity resistance exercise sessions in competitive weightlifters and resistance trained adults.

Peak force (PF), contractile rate of force development (RFD) and contractile impulse (CI) are of great importance to competitive weightlifters (WL). These athletes routinely perform successive bouts of high-intensity resistance exercise (HIRE) within the same day (double-day training) with the aim of improving muscular function and weightlifting performance. The purpose of this investigation was to determine and compare the PF, contractile RFD and CI responses to double-day training between WL and resistance trained (RT) adults (n = 16 per group). Furthermore, we sought to establish whether acute changes in muscle function were associated with acute changes in muscle architecture. Isometric front squat PF, contractile RFD, CI and the pennation angle (θ(p)), anatomical and physiological thickness of the m. vastus lateralis (VL) were determined before and after two equivalent HIRE sessions separated by 4-6 h rest. Each session consisted of ten single repetitions of the dynamic barbell front squat interspersed with 2-min rest, using a load equivalent to 90% of the pre-session PF. Weightlifters demonstrated greater PF at all time points when compared to RT adults and exhibited no significant within or between session changes in PF, contractile RFD or CI. Conversely, RT adults demonstrated within- and between-session decreases in PF and between-session increases in contractile RFD and CI. As no correlations were found between the relative within-session changes in muscle function and the concomitant changes in muscle architecture, other factors must contribute to the divergent responses in PF, contractile RFD and CI between WL and RT adults.

Reliability of cable downswing load-velocity performance in golf swings.

The cable-pulley downswing is a movement similar to the golf downswing, and therefore may offer a valuable golf specific rotational diagnostic and training tool. However, to be of value, measurements need to be stable across testing occasions. Therefore, the aim of this study was to quantify the test-retest reliability of the cable downswing across a spectrum of load-velocities. Ten male participants (21.7 ± 3.0 years, 84.6 ± 9.8 kg, 1.80 ± 0.05 m) volunteered to participate over 3 testing sessions' separated by a minimum of 3 days. Participants performed maximal velocity cable downswings across eight loads (1.25-18.75 kg), which were incrementally increased by 2.5 kg. Vertical cable stack velocity was collected at 50 Hz via a GymAware linear position transducer. Downswing velocity across all eight loads was observed to be extremely reliable (change in mean = -5.1% to 2.9%, coefficient of variation = 1.5-6.4% and intra-class correlation = 0.70-0.98), with reliability increasing with increasing trials. In conclusion, the cable downswing is a reliable method of tracking rotational ability similar to the golf downswing. Practitioners should establish an upper load relative to the apparatus and participant. Future research should determine the utility and sensitivity of this measure.

The effect of regional quadriceps anatomical parameters on angle-specific isometric torque expression.

The length-tension relationship affects knee extension performance; however, whether anatomical variations in different quadriceps regions affect this relationship is unknown. Regional (proximal, middle, distal) quadriceps thickness (MT), pennation angle, and fascicle length of 24 males (48 limbs) were assessed via ultrasonography. Participants also performed maximal voluntary isometric torque (MVIT) assessments at 40°, 70°, and 100° of knee flexion. Measures were recorded on 3 separate occasions. Linear regression models predicting angle-specific torque from regional anatomy provided adjusted simple and multiple correlations (√adjR2) with bootstrapped compatibility limits to assess magnitude. Middle vastus lateralis MT and MVIT at 100° (√adjR2 = 0.64) was the largest single correlation, with distal vastus lateralis MT having the greatest mean correlations regardless of angle (√adjR2 = 0.61 ± 0.05, mean ± SD). Lateral distal MT and architecture had larger (Δ√adjR2 = 0.01 to 0.43) single and multiple correlations with MVIT than the lateral proximal (√adjR2 = 0.15 to 0.69 vs -0.08 to 0.65). Conversely, middle anterior MT had greater (Δ√adjR2 = 0.08 to 0.38) single and multiple correlations than proximal MT (√adjR2 = 0.09 to 0.49 vs -0.21 to 0.14). The length-tension relationship was trivially affected by regional quadriceps architecture. The middle and distal quadriceps were the strongest predictors of MVIT at all joint angles. Therefore, researchers may wish to focus on middle and distal lateral quadriceps anatomy when performing ultrasonographic evaluations. Novelty: The length-tension relationship is minimally affected by regional quadriceps anatomical parameters. Middle and distal vastus lateralis and lateral vastus intermedius anatomy were consistently the best predictors of torque. Practitioners may focus their assessments on the middle and distal regions of the lateral quadriceps' musculature.