Isometric Mid-thigh Pull Research Articles

Not Lower-Limb Joint Strength and Stiffness but Vertical Stiffness and Isometric Force-Time Characteristics Correlate With Running Economy in Recreational Male Runners.

Neuromuscular characteristics, such as lower-limb joint strength, the ability to reuse elastic energy, and to generate force are essential factors influencing running performance. However, their relationship with running economy (RE) remains unclear. The aim of this study was to evaluate the correlations between isokinetic lower-limb joint peak torque (PT), lower-limb stiffness, isometric force-time characteristics and RE among recreational-trained male runners. Thirty male collegiate runners (aged 20–22 years, VO2max: 54.02 ± 4.67 ml·kg−1·min−1) participated in test sessions on four separate days. In the first session, the body composition and RE at 10 km·h−1 were determined. In the second session, leg and vertical stiffness (Kleg and Kvert), knee and ankle stiffness (Kknee and Kankle) were evaluated. In the third session, isokinetic knee and ankle joint PT at velocity of 60°s−1 were tested. The force-time characteristics of isometric mid-thigh pull (IMTP) were evaluated in the final session. The Pearson’s product-moment correlations analysis shows that there were no significant relationships between knee and ankle joint concentric and eccentric PT, Kknee and Kankle, Kleg, and RE at 10 km·h−1. However, Kvert (r = −0.449, p < 0.05) and time-specific rate of force development (RFD) for IMTP from 0 to 50 to 0–300 ms (r = −0.434 to −0.534, p < 0.05) were significantly associated with RE. Therefore, superior RE in recreational runners may not be related to knee and ankle joint strength and stiffness. It seems to be associated with vertical stiffness and the capacity to rapidly produce force within 50–300 ms throughout the lower limb.

The Influence of Instruction on Isometric Mid-Thigh Pull Force-Time Variables

Purpose: The isometric mid-thigh pull (IMTP) is commonly used to assess maximal and rapid (i.e., explosive) strength in athlete populations. The conventional IMTP instruction is to pull “as hard and fast as possible” (CON). However, previous studies using other isometric tests indicate that the use of ‘hard’ and ‘fast’ independently can result in different test outcomes. This investigation assessed the impact of a ‘hard’ only (HARD) and ‘fast’ only (FAST) instruction on IMTP kinetics when compared to the conventional combined instruction. Methods: Over three separate testing sessions, 17 National level, male, youth footballers (age: 16.4±1.3yr, mass: 69.7±8.0kg, height: 1.75±0.07m) completed three trials of the IMTP under each instruction. Peak force (N) and rapid force production, measured as impulse (N.s-1) over 50ms, 75ms, 100ms, 150ms, and 200ms were extracted and brought forward for analysis. To determine the presence of a statistical difference between conditions, a repeated measures ANOVA was employed while Cohen’s d effects sizes were used to quantify the magnitude of practical difference between each condition. Results: There was no significant or practically relevant impact of instruction condition on peak force (P &gt; 0.05, d=0.08-0.27), or impulse over any time frame (P &gt; 0.05, d=0.01-0.16). Conclusion: Practitioners can be confident that the conventional IMTP instruction is suitable for continued use in this athlete population.

Analyzing Force-Time Curves: Comparison of Commercially Available Automated Software and Custom MATLAB Analyses.

Merrigan, JJ, Stone, JD, Galster, SM, and Hagen, JA. Analyzing force-time curves: Comparison of commercially available automated software and custom MATLAB analyses. J Strength Cond Res 36(9): 2387-2402, 2022-With the growing prevalence of commercial force plate solutions providing automated force-time curve analysis, it is critical to understand the level of agreement across techniques. Thus, this study directly compared commercial and custom software analyses across force-time curves. Twenty-four male and female subjects completed 6 trials of countermovement, squat, and drop jumps, and isometric mid-thigh pulls on the same force plate. Vertical ground reaction forces were analyzed by automated software from Vald Performance, Hawkin Dynamics, and custom MATLAB scripts. Trials were visually assessed to verify proper landmark identifications. Systematic and proportional bias among analyses were compared via least products regressions, Bland-Altman plots, and percent error. Hawkin Dynamics had subtle differences in analysis procedures and demonstrated low percent errors across all tests (<3% error), despite demonstrating systematic and proportional bias for several metrics. ForceDecks demonstrated larger percent differences and greater biases for several metrics. These errors likely result from different identification of movement initiation, system weight, and integration techniques, which causes error to subsequent landmark identifications (e.g., braking/propulsive phases) and respective force-time metrics. Many metrics were in agreement between devices, such as isometric mid-thigh pull peak force consistently within 1 N across analyses, but some metrics are difficult and incomparable across software analyses (i.e., rate of force development). Overall, many metrics were in agreement across each commercial software and custom MATLAB analyses after visually confirming landmarks. However, because of inconsistencies, it is important to only compare metrics that are in agreement across software analyses when absolutely necessary.

Low-Load Blood Flow Restriction Squat as Conditioning Activity Within a Contrast Training Sequence in High-Level Preadolescent Trampoline Gymnasts.

To investigate the effects of implementing low-load blood flow restriction exercises (LL-BFRE) instead of high-load exercises (HL-RE) in a contrast training program on strength and power performance of high-level young gymnasts. Fifteen high-level pre-pubescent trampoline gymnasts (national level, Tanner Stage II, intermediate experience in strength training) were divided into two groups to complete the same structure of a ten-week contrast strength training program differing only in the configuration of the first resistance exercise of the contrast sequence. The LL-BFRE group (n = 7, four girls, 13.9 ± 0.4 y) performed the first resistance exercise of the contrast with LL-BFRE (20%–30% 1RM, perceived pressure of 7 on a scale from 0 to 10). The HL-RE group (n = 8, four girls, 13.8 ± 0.5 y) trained the first resistance exercise of the contrast sequence with moderate-to-high load (60%–85% 1RM). Before and after the training period, isometric mid-thigh pull (IMTP), squat jump (SJ), counter movement jump (CMJ), and drop-jump (DJ) were performed to evaluate the effect of the intervention on strength and power capacities as primary outcomes. Changes in participants’ anthropometric measures, muscle mass, left and right thigh girth, IMTP relative to bodyweight (IMTP-R), eccentric utilization ratio (EUR), and reactive strength index (RSI) were assessed as secondary outcomes. There was no significant interaction (p > 0.05) between group x time in any power and strength outcome, although SJ and EUR showed a trend to significant interaction (p = 0.06 and p = 0.065, respectively). There was an overall effect of time (p < 0.05) in all power and strength variables (CMJ, SJ, EUR, DJ, RSI, IMTP, and IMTP-R). There was a significant interaction in muscle mass (MM) [β = 0.57 kg, 95% CI = (0.15; 0.98), t13 = 2.67, p = 0.019], revealing that participants in LL-BFRE increased their muscle mass (6.6 ± 3.1%) compared to HL-RE (3.6 ± 2.0%). Anthropometric variables did not present any group or interaction effect. However, there was a time effect (p < 0.05). Implementing LL-BFRE in place of HL-RE as a conditioning activity in a contrast training sequence might be equally effective in improving lower-body strength and power in preadolescent trampoline gymnasts.

Relationship between isometric force-time curve variables and serve velocity in young tennis players

ABSTRACT This study aimed to investigate the associations between serve velocity (SV), maximal absolute and relative isometric voluntary contraction (MVC and RMVC), peak rate of force development (PRFD), rate of force development (RFD) and impulse (IMP) at different stages of contraction (≤200 ms). Sixteen players performed four maximum isometric tests in positions involved in the tennis serve motion. Variables tested included MVC, PRFD, RFD and IMP at 50, 100, 150 and 200 ms while performing a 90º shoulder internal rotation (SHIR), shoulder flexion (SHF), horizontal shoulder abduction (SHABD) and an isometric mid-thigh pull (IMTP). Significant (p ≤ 0.05) moderate-to-very-large correlations were found between SV, MVC and PRFD. RFD at different time intervals showed positive associations with SV, except in the SHF0-200 ms and IMTP0-200 ms. Accordingly, IMP values positively correlated with SV in all positions except in the SHIR0-50 ms and the IMTP in late contraction stages. Results indicate that the combination of maximum isometric strength in several body positions involved in the serve kinetic chain alongside RFD and IMP in short periods of time (≤200 ms) positively influences SV in young participants.

Assessing Physical Fitness of Athletes in a Confined Environment during Prolonged Self-Isolation: Potential Usefulness of the Test of Maximal Number of Burpees Performed in 3 Minutes.

Due to a prolonged period of quarantine during the COVID-19 pandemic, it is essential to monitor the physical condition of athletes isolated at home with a fitness tool that measures various aspects of physical fitness, which does not require any special equipment, and can be performed within a small space. This study assessed the reliability and validity of the test of performing the maximal number of burpees in 3 min (or 3-MBT) to monitor strength, power, and aerobic endurance in trained athletes. For Part I (reliability of the 3-MBT), 20 (10 male, 10 female) national athletes from various sports performed the 3-MBT on two separate test sessions. Athletes performed as many burpees as possible within 3 min and the primary performance criteria was the number of burpees completed (where a higher number reflected a better performance). The 3-MBT displayed excellent relative reliability in the athletes, with an intraclass correlation coefficient (ICC) and coefficient of variation (CV %) of >0.92, and <3.0%, respectively. For Part II (validity of the 3-MBT), 40 (20 M, 20 F) athletes performed the 3-MBT, and the countermovement jump (CMJ), isometric mid-thigh pull (IMTP), seated medicine ball throw (SMBT), isometric bench (IBP) and maximal aerobic power (VO2max) tests on separate sessions. When data of male and female athletes were pooled, there were significant correlations between relative 3-MBT and relative CMJ height (r = 0.65, large; p < 0.001), relative IMPT peak force (r = 0.50, large; p < 0.001), relative IBP peak force (r = 0.36, moderate, p = 0.02), and relative VO2max (r = 0.50, large; p < 0.001). In conclusion, the 3-MBT is a reliable and reasonably useful test and is a valid assessment of lower body power and strength, upper body strength and aerobic fitness in trained male and female athletes.

Comparing the Effects of Long-Term vs. Periodic Inclusion of Isometric Strength Training on Strength and Dynamic Performances.

Lum, D, Joseph, R, Ong, KY, Tang, JM, and Suchomel, TJ. Comparing the effects of long-term vs. periodic inclusion of isometric strength training on strength and dynamic performances. J Strength Cond Res 37(2): 305-314, 2023-This study compared the effects of including isometric strength training (IST) for consecutive 24 weeks (CIST) against a periodic inclusion (PIST) of this mode of training on strength and dynamic performances. Twenty-four floorball athletes (age: 23 ± 2.7 years, stature: 1.74 ± 2.08 m, and body mass: 72.7 ± 14.4 kg) were randomly assigned to the control (CON), CIST, or PIST group. Athletes completed 20-m sprint, countermovement jump (CMJ), and isometric midthigh pull (IMTP) during pre-test and were tested on weeks 6, 12, 18, and 24. All groups performed a similar strength training program twice per week. However, 2 sets of squats were replaced with isometric squat in CIST for all 24 weeks but only on weeks 1-6 and 13-18 for PIST. A significant main effect for time was observed for 5-, 10-, and 20-m sprint time, CMJ height, peak force, peak power, time to take-off, modified reactive strength index, IMTP peak force, relative peak force, and force at 200 milliseconds ( p = <0.001-0.037). Isometric strength training for 24 consecutive weeks resulted in greater improvement in 5-m sprint time than CON at week 24 ( p = 0.024, g = 1.17). Both CIST and PIST resulted in greater improvements in 10-m sprint time than CON at various time points ( p = 0.007-0.038 and 0.038, g = 1.07-1.44 and 1.18, respectively). Isometric strength training for 24 consecutive weeks and PIST resulted in greater improvements in 20-m sprint time than CON at week 6 ( p = 0.007 and 0.025, g = 1.65 and 1.40, respectively). The results showed that the inclusion of IST resulted in greater improvements in sprint performance than CON but no significant difference in all measured variables with PIST.

Force-Time Curve Variable Outcomes Following a Simulated Tennis Match in Junior Players.

This study examined the alterations induced by a simulated tennis competition on maximal isometric voluntary contraction (MVC), peak rate of force development (PRFD) and rate of force development (RFD) at different stages of contraction. Twenty junior tennis players performed an 80-minute simulated tennis match and two (pre and post) muscular performance tests. Variables tested included MVC, PRFD and RFD at 50, 100, 150 and 200 ms while performing a 90º shoulder internal rotation (IR90), 90º shoulder external rotation (ER90), shoulder horizontal adduction (ADD), shoulder horizontal abduction (ABD) and isometric mid-thigh pull (IMTP). Serve velocity (SV) was also registered. No significant changes were found regarding MVC, PRFD or SV. Non-significant moderate effect size (ES) towards a decrease in the IR90 RFD at 50 ms could be observed (16%; ES = 0.5) alongside an increase in the ADD and IMTP RFD at 150 ms (-15.8%, -8.2%; ES = -0.53, -0.54) and IMTP RFD at 200 ms (-13%; ES = -0.54). Results indicate that MVC, PRFD, RFD at different time intervals and SV are unaltered following an 80-minute simulated match, possibly due to insufficient alterations triggered on key factors affecting the tested variables.

Effects of Isometric Strength and Plyometric Training on Running Performance: A Randomized Controlled Study

ABSTRACT Purpose: The aim of the study was to compare the effects of isometric strength (IST) and plyometric training (PT) on endurance running performance. Methods: Twenty-six endurance runners (18 males and 8 females; age 36 ± 6 years, stature 1.69 ± 0.05 m body mass 61.6 ± 8.0 kg, VO2max 50.4 ± 5.8 ml·kg−1·min−1) completed the countermovement jump (CMJ), isometric mid-thigh pull (IMTP), 2.4 km run time trial (2.4kmTT), running economy test (RE) and a graded exercise test measures at baseline. They were then randomly assigned to three groups, the control (CON), PT or IST group, and completed the circuit, plyometric or isometric training, respectively, twice a week for 6 weeks, while still continuing to perform their planned running training. They then completed the same set of measures performed at baseline post-intervention. Results: Significant time x group interactions and time main effect were observed for 2.4kmTT (P = .002, ƞ2 p = .45 and P < .001, ƞ2 =0.72), maximal aerobic speed (MAS) (P = .006, ƞ2 p = .39), CMJ height (P < .001, ƞ2 p = .55) and IMTP relative peak force (P = .001, ƞ2 p = .50) in favor of PT and IST. Significant main effect for time was observed for 2.4kmTT (P < .001, ƞ2 p = .72), RE (P = .048, ƞ2 p = .17), VO2max (P = .047, ƞ2 p = .18), MAS (P < .001, ƞ2 p = .63), CMJ height (P < .001, ƞ2 p = .51) and IMTP relative peak force (P < .001, ƞ2 p = .58). Conclusion: In conclusion, both PT and IST were similarly effective at enhancing running endurance performance. However, IST resulted in greater improvement to RE.

The Reliability and Magnitude of Time-Dependent Force-Time Characteristics During the Isometric Midthigh Pull Are Affected by Both Testing Protocol and Analysis Choices.

Guppy, SN, Kotani, Y, Brady, CJ, Connolly, S, Comfort, P, and Haff, GG. Title: The reliability and magnitude of time-dependent force-time characteristics during the isometric mid-thigh pull are impacted by both testing protocol and analysis choices. J Strength Cond Res 36(5): 1191-1199, 2022-This study aimed to investigate whether the use of short-duration (SHORT) isometric midthigh pull (IMTP) trials resulted in greater reliability and magnitude of time-dependent force-time characteristics than traditionally performed IMTP trials (TRAD). Fourteen subjects with >6 months' training experience with the power clean volunteered to take part in the study. Subjects performed five ∼1-second IMTP trials (SHORT) and five 5-second IMTP trials (TRAD). SHORT resulted in substantially more reliable rate of force development (RFD) measures (intraclass correlation coefficient [ICC] = 0.97-0.99; coefficient of variation [CV] = 2.6-7.0%), particularly during time bands from force-onset to 150 ms, compared with TRAD when trials were selected for analysis based on peak force (ICC = 0.66-0.83; CV = 14.1-38.5%). Selecting TRAD trials based on RFD0-200 resulted in similar reliability compared with SHORT of those same epochs (ICC = 0.97-0.99; CV = 2.5-7.8%). Furthermore, SHORT resulted in significantly greater force at specific time points, RFD, and impulse compared with TRAD trials (p = 0.001-0.033; g = -0.16 to -0.66). Based on these results, strength and conditioning professionals should use specific testing protocols (i.e., TRAD and SHORT) depending on the component of an athlete's force-generating capacity that they wish to assess and remain aware of the effect analysis choices they have on the reliability of IMTP force-time characteristics.

Improved performance in youth netballers using two different length netball specific warm-ups

Purpose Neuromuscular warm-up has been shown to reduce injury risk and improve performance; however, barriers to implementation are common. To improve uptake by coaches Netball New Zealand developed two warm-ups of differing complexity and duration. This multi-site trial investigated the association between two netball specific warm-ups and improvements in performance outcome in youth netball players. Methods Twelve teams from six schools performed either the NetballSmart Dynamic Warm-up (NSDW, n = 37); or Power warm-up (PWU, n = 40), three times a week for 12 weeks. Performance was measured using 505 change-of-direction (COD), isometric mid-thigh pull (IMTP), Y-balance, vertical jump (VJ) and horizontal jump (HJ) tests. Paired t-tests assessed mean differences pre and post the interventions. Generalised linear mixed effects models evaluated effects between the NSDW and PWU groups. Results There was no significant difference between the NSDW or PWU for any of the outcomes (all p &gt; 0.05). Significant improvements were found in Y-balance (NSDW: Right (R) = 6.4 cm, Left (L) = 7.5 cm, p = 0.001; PWU: R = 4.2 cm, p = 0.004, L = 4.2, p = 0.006) and IMTP (NSDW: 162N; p = 0.001 PWU: 151N, p = 0.001) for both warm-up groups, and the NSDW also enhanced 505 performance (-0.07 s, p = 0.024). VJ and HJ failed to improve for either warm-up. Conclusion Based on performance outcomes coaches should be free to choose the warm-up they feel best fits their team environment, reducing barriers to implementation. Additionally, they may benefit from adding further COD, horizontal and vertical jumping movements to either their warm-up or skills training sessions.

Effects of a 10-Month Neuromuscular Training Program on Strength, Power, Speed, and Vault Performance in Young Female Gymnasts.

This study aimed to evaluate a 10-month neuromuscular training (NMT) intervention on isometric and dynamic kinetics, standing long jump (SLJ) distance, speed, and sport-specific performance. Forty-three prepubertal female gymnasts were allocated into either a gymnastics + NMT (gNMT; n = 16), gymnastics only (GYM, n = 15), or maturity-matched control (CON; n = 12) group. The gNMT followed a 10-month, twice-weekly NMT program that targeted movement competency, strength, power, and speed. Vaulting vertical take-off velocity, speed, SLJ distance, and kinetics during an isometric mid-thigh pull (IMTP), countermovement jump (CMJ), and drop jump (DJ) were measured at baseline and thereafter at 4, 7, and 10 months. Within-group differences were calculated using 3 × 4 repeated-measures ANCOVA. Interaction effects were observed for SLJ distance and various IMTP, DJ, and vaulting variables. The gNMT showed significant improvements in IMTP absolute force and SLJ distance after 4 months and each subsequent testing session. IMTP relative force and various CMJ and DJ kinetics significantly improved in the gNMT from 7 months. Significant gains in speed and vaulting take-off velocity occurred after 10 months. The GYM group achieved some significant improvements in CMJ impulse, absolute isometric strength, and DJ spring-like behavior, whereas the CON group did not experience any changes. The addition of NMT to gymnastics training improved various isometric and dynamic kinetics, SLJ distance, speed, and vaulting take-off velocity in the gNMT, changes that were not equally evidenced for GYM or CON. The threshold for most of the training-induced adaptations observed in IMTP relative force, CMJ and DJ kinetics, sprint speed, and vaulting were achieved after 7 months, emphasizing the efficacy of long-term NMT programs for young gymnasts.

Relationship Between Isokinetic Lower-Limb Joint Strength, Isometric Time Force Characteristics, and Leg-Spring Stiffness in Recreational Runners.

Neuromuscular characteristics, such as lower-limb joint strength and the ability to rapidly generate force, may play an important role in leg-spring stiffness regulation. This study aimed to investigate the relationship between isokinetic knee and ankle joint peak torque (PT), the force-time characteristics of isometric mid-thigh pull (IMTP), and leg stiffness (Kleg)/vertical stiffness (Kvert) in recreationally trained runners. Thirty-one male runners were recruited and underwent three separate tests. In the first session, the body composition, Kleg, and Kvert at running speeds of 12 and 14 km⋅h–1 were measured. In the second session, isokinetic knee and ankle joint PT at 60°⋅s–1 were tested. The force-time characteristics of the IMTP were evaluated in the final session. Pearson’s product-moment correlations, with the Benjamini–Hochberg correction procedure, showed that the knee flexor concentric and eccentric and extensor concentric PT (r = 0.473–0.654, p < 0.05) were moderate to largely correlated with Kleg and Kvert at 12 and 14 km⋅h–1. The knee extensor eccentric PT (r = 0.440, p = 0.050) was moderately correlated with the 14 km⋅h–1 Kvert. The ankle plantar flexor concentric and dorsiflexor eccentric PT (r = 0.506–0.571, p < 0.05) were largely correlated with Kleg at 12 km⋅h–1. The ankle plantar flexor concentric and eccentric and dorsiflexor eccentric PT (r = 0.436–0.561, p < 0.05) were moderate to largely correlated with Kvert at 12 and 14 km⋅h–1. For IMTP testing, high correlation was only found between the IMPT peak force (PF) and Kvert at 14 km⋅h–1 (r = 0.510, p = 0.014). Thus, superior leg-spring stiffness in recreational runners may be related to increased knee and ankle joint strength, eccentric muscular capacity, and maximal force production.

Comparing the effects of plyometric and isometric strength training on dynamic and isometric force-time characteristics.

The purpose of the study was to compare the change in dynamic and isometric force-time characteristics after plyometric (PLYO) or isometric strength training (ISO). Twenty-two endurance runners (age = 37 ± 6 years, stature = 1.71 ± 0.05 m, body mass = 62.7 ± 8.6 kg, weekly mileage = 47.3 ± 10.8 km) performed a countermovement jump (CMJ) and isometric mid-thigh pull (IMTP) test during pre- and post-tests. They were then randomly assigned to either PLYO or ISO group and completed 12 sessions of intervention over six weeks. The PLYO included drop jump, single leg bounding and split jump, and the ISO included IMTP and isometric ankle plantar flexion. Significant and large time x group interactions were observed for CMJ countermovement depth (P = 0.037, ƞ²p = 0.21) and IMTP and relative peak force (PF) (P = 0.030, ƞ²p = 0.22). Significant and large main effects for time were observed in CMJ height, peak power, propulsive phase duration, countermovement depth, reactive strength index modified, IMTP PF and relative PF (P < 0.05, 0.20 ≤ ƞ²p ≤ 0.65). Effect for time showed small improvement in CMJ height for both PLYO (P < 0.001, d = 0.48) and ISO (P = 0.009, d = 0.47), small improvement in CMJ PP in PLYO (P = 0.020, d = 0.21), large increase in countermovement depth (P = 0.004, d = 1.02) and IMTP relative PF (P < 0.001, d = 0.87), and moderate increase in propulsive phase duration (P = 0.038, d = 0.65) and IMTP PF (P < 0.001, d = 0.55) in ISO. There were large differences between groups for percentage change in countermovement depth (P = 0.003, d = 0.96) and IMTP relative PF (P = 0.047, d = 0.90). In conclusion, both PLYO and ISO improved CMJ jump height via different mechanisms, while only ISO resulted in improved IMTP PF and relative PF.

Effect of Previous-Day Alcohol Ingestion on Muscle Function and Performance of Severe-Intensity Exercise.

Many athletes report consuming alcohol the day before their event, which might negatively affect their performance. However, the effects of previous-day alcohol ingestion on performance are equivocal, in part, due to no standardization of alcohol dose in previous studies. The purpose of this study was to examine the impact of a standardized previous-day alcohol dose and its corresponding impact on morning-after muscular strength, muscular power, and muscular fatigue in a short-duration test and on performance of severe-intensity exercise. On 2 occasions, 12 recreationally active individuals reported to the Applied Physiology Laboratory in the evening and ingested a beverage containing either 1.09 g ethanol·kg-1 fat-free body mass (ALC condition) or water (PLA condition). The following morning, they completed a hangover symptom questionnaire, vertical jumps, isometric midthigh pulls, biceps curls, and a constant-power cycle ergometer test to exhaustion. The responses from ALC and PLA were compared using paired-means t tests. Time to exhaustion in the cycle ergometer tests was less (P = .03) in the ALC condition (181 [39] s vs 203 [34] s; -11%, Cohen d = 0.61). There was no difference in performance in vertical jump test, isometric midthigh pulls, and biceps curls tests between the ALC and PLA conditions. Previous-day alcohol consumption significantly reduces morning-after performance of severe-intensity exercise. Practitioners should educate their athletes, especially those whose events rely on anaerobic capacity and/or a rapid response of the aerobic pathways, of the adverse effect of previous-day alcohol consumption on performance.

Intrasession and Intersession Reliability of Isometric Squat, Midthigh Pull, and Squat Jump in Resistance-Trained Individuals.

Ishida, A, Suarez, DG, Travis, SK, Slaton, JA, White, JB, Bazyler, CD, and Stone, MH. Intrasession and intersession reliability of isometric squat, midthigh pull, and squat jump in resistance-trained individuals. J Strength Cond Res 37(1): 18-26, 2023-The purposes of this study were to investigate intrasession and intersession reliability of variables obtained from squat jump (SJ), shortened isometric midthigh pull (IMTP), and isometric squat (ISQ) protocols and to evaluate relationships between isometric and dynamic performance and 1 repetition maximum (1RM) back squat (BSQ). Eleven moderately resistance-trained men participated (27.8 ± 3.9 years; 175.0 ± 7.2 cm; 87.2 ± 11.4 kg). Subjects completed familiarization in the IMTP and ISQ, followed by 1RM BSQ at least 48 hours before the first performance test. Two performance tests occurred at 7-day intervals including SJ, IMTP, and ISQ. SJ variables included jump height (SJH), body mass (BM), peak force (PF), and peak power (PP). Isometric midthigh pull and ISQ variables included isometric peak force (IPF); relative IPF; rate of force development at 90, 200, and 250 milliseconds; and impulse at 90, 200, and 250 milliseconds. SJ, IMTP, and ISQ kinetic variables were considered reliable if intraclass correlations (ICCs) and coefficients of variations (CVs) were >0.80 and <10%. Intrasession and intersession reliability criteria were met for SJH, BM, PF, and PP (ICC = 0.91-1.00, CV = 0.5-9.1%). Isometric peak force and impulse at 200 and 250 milliseconds met intrasession and intersession reliability criteria for IMTP and ISQ (ICC = 0.90-0.99, CV = 2.1-8.1%). Significant large correlation was observed between 1RM BSQ and ISQ peak force (p = 0.038, r = 0.63), but not between 1RM BSQ and shortened IMTP peak force (p = 0.11, r = 0.50). Shortened IMTP and ISQ peak force and impulse are reliable kinetic variables, and ISQ peak force is indicative of 1RM BSQ in moderately resistance-trained men.

Post-activation Performance Enhancement after a Bout of Accentuated Eccentric Loading in Collegiate Male Volleyball Players.

The purpose of this study was to investigate the benefit of post-activation performance enhancement (PAPE) after accentuated eccentric loading (AEL) compared to traditional resistance loading (TR). Sixteen male volleyball athletes were divided in AEL and TR group. AEL group performed 3 sets of 4 repetitions (eccentric: 105% of concentric 1RM, concentric: 80% of concentric 1RM) of half squat, and TR group performed 3 sets of 5 repetitions (eccentric & concentric: 85% of 1RM). Countermovement jump (CMJ), spike jump (SPJ), isometric mid-thigh pull (IMTP), and muscle soreness test were administered before (Pre) exercise, and 10 min (10-min), 24 h (24-h), and 48 h (48-h) after exercise. A two-way repeated measures analysis of variance was used to analyze the data. Peak force and rate of development (RFD) of IMTP in AEL group were significantly greater (p < 0.05) than TR group. The height, peak velocity, and RFD of CMJ, height of SPJ, and muscle soreness showed no interaction effects (p > 0.05) groups x time. AEL seemed capable to maintain force production in IMTP, but not in CMJ and SPJ. It is recommended the use of accentuated eccentric loading protocols to overcome the fatigue.

Comparisons and Intercorrelations of Physical Performance Variables of Operational Preparedness in Special Operations Forces.

Marine Forces Special Operations Command (MARSOC) deploys teams of operators (OP) and enablers (EN) to accomplish special operations missions. OP and EN are required to train and deploy together to accomplish these missions; however, they have different training and selection pipelines. Advanced strength and conditioning training strategies are applied to both OP and EN to enhance physical preparedness; however, it is unclear how the selection pipeline of these two personnel types affects overall physical preparedness and the relationships between performance variables. The purpose of this study is to gain a greater understanding of the relationships of a wide array of physical preparedness variables in OP and EN in an effort to streamline testing and training strategies. For this study, 155 male (82 OP, 73 EN) MARSOC personnel (age: 29.5 ± 4.9 years, mass: 87.9 ± 11.1 kg, height: 1.79 ± 0.07 m) completed a physical preparedness assessment that included a DEXA assessment of body composition (BF%), 27.4 m sprint (30 yd), countermovement jump (VJ), 5-10-5 pro-agility (Agility), medicine ball toss (UBP), isometric mid-thigh pull (IMTP), and a 30 second (AnC) and 5 minute (AC) non-motorized treadmill run. Independent samples t tests, Mann-Whitney U tests, and Spearman's Rank correlations were used to compare variables between OP and EN. OP demonstrated greater VJ, UBP, IMTP, AnC, and AC (P < 0.05); and significantly lower BF% and agility time (P < 0.05). Measurements of mass, height, body mass index, and 30 yd were not significantly different (P > 0.05). Weak to moderate correlations were seen between anthropometric and performance variables. OP and EN demonstrated similar correlations for most performance and anthropometric variables. These results suggest that MARSOC OP demonstrate better physical preparedness over EN, while similar trends are observed between performance variables. Tests with moderate to high correlations may be removed from the protocol to account for testing time constraints. Height, weight, and BF% variables are poorly correlated with performance, particularly in OP, questioning their value in physical performance assessments in this population.

Which physical attributes discriminate between faster and slower elite cricket pace bowlers of each sex?

Background: Ball release speed is an important quality of successful performance in pace bowlers. There is limited evidence available regarding the association between physical attributes and ball release speed in elite male pace bowlers, and no studies that have investigated the physical attributes associated with ball release speed in female pace bowlers. The purpose of this study therefore, was to elucidate which physical attributes discriminates between faster and slower elite cricket pace bowlers of each sex. Methods: Ball release speed and physical testing data from sixty-three elite male and thirty-one elite female pace bowlers from the 2014/15 season to the 2020/21 season were retrospectively analysed. Pace bowlers were classified as either “slower” (females: < 97.8 km/h; males: < 122.9 km/h) or “faster” (females: > 97.8 km/h; males: > 122.9 km/h) via a median split. From the five physical tests, six absolute variables were collected. Each absolute variable was normalised to body weight resulting in a total of twelve physical attributes. These twelve physical attributes were compared between the slower and faster groups for each sex. The differences between groups were compared using magnitude-based inferences (Cohen’s d). Results: Faster male bowlers produced greater absolute (d = 0.25) and relative (d = 0.62) peak force in the isometric mid-thigh pull (IMTP), as well as greater absolute (d = 0.39) and relative (d = 0.61) countermovement jump (CMJ) height compared to their slower counterparts. Faster female bowlers also produced greater absolute (d = 0.68) and relative (d = 0.77) peak force in the IMTP, greater 1RM bench pull strength (d = 0.45) and superior run of three performance (relative average, d = 1.22; relative best, d = 1.12; average, d = 0.49; and best d = 0.40) and superior 1RM bench pull strength (d = 0.45). Discussion: Greater lower body maximal isometric strength discriminates between faster and slower bowlers, irrespective of sex. Lower body power (assumed via CMJ height) appears to be an important physical attribute for faster male bowlers. Superior anaerobic capacities separated faster female pace bowlers from their slower counterparts. Further research should assess rate of force development qualities of the lower and upper body musculature associated with desirable biomechanics, to provide a more complete understanding of the physical attributes that may distinguish between slower and faster bowlers of each sex. Conflict of interest statement: The authors would like to acknowledge Dr Anna Saw, Dr Kevin Sims and Dr Alex Kountouris from Cricket Australia, for the support, access and use of ball speed and physical testing data. This work was supported by a Deakin University Postgraduate Research Scholarship as a part of a doctorate degree.

Effects of Training Frequency During a 6-Month Neuromuscular Training Intervention on Movement Competency, Strength, and Power in Male Youth.

Background:Youth populations benefit from neuromuscular training; however, the extent to which training frequency, baseline fitness, and maturity status moderate the response to long-term neuromuscular training in male youth remains unclear.Hypothesis:Twice-weekly training (G2x) would induce larger improvements in movement competency and strength and power kinetics compared with once-weekly training (G1x). Maturity status and baseline fitness would also moderate the training response in strength and power kinetics.Study Design:Nonrandomized, repeated-measures design.Level of Evidence:Level 3Methods:Ninety-five male athletes of varying maturity status (pre– or post–peak height velocity) were divided into G2x, G1x, or control (CON) groups. Training groups received G2x or G1x for 28 weeks. Back squat assessment (BSA) movement competency and isometric mid-thigh pull (IMTP), squat jump (SJ), and countermovement jump (CMJ) kinetics were measured pre- and postintervention.Results:The G2x achieved significantly greater adaptations in BSA total score, IMTP allometrically scaled peak force (PFallo), IMTP peak rate-of-force development (PRFD), SJ PFallo and PRFD compared with G1x and CON (P < 0.05; d = 0.3-0.9). Baseline fitness, training frequency and maturity status were significant predictors of IMTP PFallo (R2 = 27.5%) and PRFD (R2 = 42.9%), while a combination of training frequency and baseline fitness explained a small amount of variance in SJ PFallo (R2 = 12.2%) and SJ PRFD (R2 = 6.5%). There were no significant predictors of CMJ kinetics.Conclusion:G2x achieved significantly larger improvements in movement competency, isometric strength and concentric jump variables compared with G1x, with the training response greater in those youth with lower baseline fitness and more advanced maturity status.Clinical Relevance:Exposure to neuromuscular training twice-weekly elicits a greater response than G1x in young male athletes. Practitioners should take maturity status, training frequency, and baseline fitness levels of young male athletes into account when interpreting testing data, as these variables appear to moderate training responsiveness.