Propulsive Velocity Research Articles

Variations in mean propulsive velocity responses during bench press exercise across different inter-set rest intervals

Variations in mean propulsive velocity responses during bench press exercise across different inter-set rest intervals

Acute Effect of Fixed vs. Self-Selected Rest Interval Between Sets on Physiological and Performance-Related Responses.

Background: Although the comparison between self-managed rest and fixed rest periods in subjects experienced in lower-limb strength training has been investigated, the results remain unclear due to controversies among some studies. Therefore, the present study aimed to analyze the role of self-managed rest versus fixed rest in athletic performance, mean propulsive velocity, velocity loss, muscle oxygen saturation, and rest time in trained subjects; Methods: Thirteen subjects with a minimum of one year of training experience (age (years): 26.31 ± 3.84; height (cm): 175.46 ± 5.61; weight (kg): 79.24 ± 6.83) were randomly assigned to two groups (self-selected rest group [SR] = 7 and fixed rest group [FR] = 6). The subjects underwent a session for evaluation (one maximum repetition (1RM) estimation, familiarization, and data collection) and another day for a traditional strength training session for the back squat, consisting of five sets of four repetitions at 80% of 1RM. One group took a fixed 2 min break, while the other group managed their breaks autonomously (resuming when they felt ready to perform the next set at maximum velocity). Mean propulsive velocity (MPV) was monitored using a linear position transducer, and muscle oxygen saturation (SmO2) was measured with a near-infrared spectroscopy device; Results: Significant differences between the groups were found for the rest time between the first and second sets (SR 97.29 ± 23.70 seg vs. FR 120 ± 0.00 seg). However, no differences were found for MPV, velocity loss, or SmO2; Conclusions: Given the similarities in performance and physiological outcomes between fixed and self-selected rest conditions, both can be used equally depending on the preferences and training goals of coaches and athletes.

Submaximal force–velocity relationships during mountain ultramarathon: Data from the field

ABSTRACT This study presents a novel method for evaluating the submaximal velocity-force (V(F)) relationship in mountain ultramarathon races using crowdsourced data from Strava.com. The dataset includes positional data from 408 participants of the 171-km UTMB® 2023 race (9,850-m D+). The race was divided into 100-m segments. The mean net propulsive force and velocity were computed for each segment to describe the submaximal V(F) relationship as a rational function of three parameters. F1: propulsive force at 1 m · s−1; V0: theoretical maximum velocity on flat terrain; C: curvature parameter (the lower C, the more linear the V(F) relationship). The V(F) profile parameters were found to be F1 = 1.80 ± 0.33 N · kg−1, V0 = 2.36 ± 0.42 m · s−1, and C = 0.66 ± 1.81, with good independence between the parameters within a group of homogeneous performance. The best athletes had the highest F1, V0, and C values. V(F) parameters were affected by fatigue during the race, with decreases of 20.9%, 32.0%, and 59.8% between the first and second parts of the race respectively. These findings suggest that the V(F) relationship is an interesting original approach for studying performance and fatigability during mountain ultra-endurance races.

Validity and Concordance of a Linear Position Transducer (Vitruve) for Measuring Movement Velocity during Resistance Training.

This study aimed to analyze the intra-device agreement of a new linear position transducer (Vitruve, VT) and the inter-device agreement with a previously validated linear velocity transducer (T-Force System, TF) in different range of velocities. A group of 50 healthy, physically active men performed a progressive loading test during a bench press (BP) and full-squat (SQ) exercise with a simultaneous recording of two VT and one TF devices. The mean propulsive velocity (MPV) and peak of velocity (PV) were recorded for subsequent analysis. A set of statistics was used to determine the degree of agreement (Intraclass correlation coefficient [ICC], Lin's concordance correlation coefficient [CCC], mean square deviation [MSD], and variance of the difference between measurements [VMD]) and the error magnitude (standard error of measurement [SEM], smallest detectable change [SDC], and maximum errors [ME]) between devices. The established velocity ranges were as follows: >1.20 m·s-1; 1.20-0.95 m·s-1; 0.95-0.70 m·s-1; 0.70-0.45 m·s-1; ≤0.45 m·s-1 for BP; and >1.50 m·s-1; 1.50-1.25 m·s-1; 1.25-1.00 m·s-1; 1.00-0.75 m·s-1; and ≤0.75 m·s-1 for SQ. For the MPV, the VT system showed high intra- and inter-device agreement and moderate error magnitude with pooled data in both exercises. However, the level of agreement decreased (ICC: 0.790-0.996; CCC: 0.663-0.992) and the error increased (ME: 2.8-13.4% 1RM; SEM: 0.035-0.01 m·s-1) as the velocity range increased. For the PV, the magnitude of error was very high in both exercises. In conclusion, our results suggest that the VT system should only be used at MPVs below 0.45 m·s-1 for BP and 0.75 m·s-1 for SQ in order to obtain an accurate and reliable measurement, preferably using the MPV variable instead of the PV. Therefore, it appears that the VT system may not be appropriate for objectively monitoring resistance training and assessing strength performance along the entire spectrum of load-velocity curve.

Influence of menstrual cycle and oral contraceptive phases on strength performance, neuromuscular fatigue, and perceived exertion.

The primary aim of the study was to assess differences in strength performance, neuromuscular fatigue, and perceived exertion across phases of the menstrual cycle [MC; early follicular (eFP), late follicular (lFP), and mid-luteal phase (mLP)] and oral contraceptives [OCs; active pill phase (aPP) and nonactive pill phase (nPP)]. The secondary aim was to analyze the influence of fluctuating serum 17β-estradiol and progesterone concentrations on these parameters in naturally menstruating women. Thirty-four women (21 with a natural MC and 13 using OCs) completed three or two experimental sessions, respectively. Mean propulsive velocity (MPVmean) and total number of repetitions (REPtotal) were assessed during a power [3 × 8 at 60% 1RM (one-repetition maximum)] and hypertrophy squat loading (3 sets to failure at 70% 1RM), respectively. Changes in bench press and squat MPV at 60% 1RM in response to the loadings were used as surrogates for nonlocal and local fatigue, respectively. Total blood lactate accumulation (BLAA) and markers of perceived exertion were assessed in each session. No significant differences between any of the MC or OC phases were observed for MPVmean, REPtotal, nonlocal and local fatigue, and markers of perceived exertion (all P > 0.050). A higher intraindividual 17β-estradiol concentration was significantly associated with a lower MPVmean (P = 0.019). BLAA was significantly higher in the lFP than in the mLP (P = 0.019) and negatively associated with the intraindividual progesterone concentration (P = 0.005). Although 17β-estradiol may negatively influence the MPV, it appears that fluctuations of both sex hormones across the MC and OC phases are not prominent enough to induce significant or practically relevant changes in the assessed parameters.NEW & NOTEWORTHY Although a high intraindividual 17β-estradiol concentration was associated with a lower movement velocity, markers of strength performance and surrogates for nonlocal and local fatigue remained unaffected by MC and OC phases. Blood lactate accumulation was significantly reduced in the mLP. Furthermore, our findings suggest that the impact of the MC phases varies greatly among individuals. Individuals with high fluctuations in sex hormone concentrations may experience relevant changes in the assessed parameters.

Exploring the validity of perceived velocity in lower-limb resistance exercises with a cluster-set configuration

This feasibility study aimed to explore the relationship between mean propulsive velocity (MPV) and a scale of perceived velocity (SPV) in back-squat and deadlift exercises performed with heavy loads during a cluster-sets resistance training (CS-RT). Twelve resistance trained males (24.1[2.94] years; 80.7[9.05] kg; 172[4.7] cm; 19.1[6.17] %BF; 4.71[2.72] years of training experience) participated. Participants visited the laboratory three times, spaced 72 to 96 hours. Load-velocity profiles for each exercise were measured in first visit. During the second and third visits, participants engaged in CS-RT sessions with different intra-set rest period (20 vs 40 seconds, randomly), and consisted of three sets of squat and deadlift exercises at 80%1-RM. Each set concluded upon reaching a 10% velocity loss on two occasions. Bayesian Pearson correlation coefficients (r), 95% credible intervals (95%CrI) and Bayes factors (BF10) were computed to assess the relationship between variables. A low positive correlation was observed between MPV and SPV in deadlift (r=0.368, 95%CrI [0.144, 0.544]), with strong evidence supporting the alternative hypothesis (BF10=20.7). Interestingly, moderate correlation values were observed in the 40-second CS-RT configuration (r=0.47, 95%CrI [0.144, 0.544]) and in the first set of the deadlift (r=0.44, 95%CrI [0.118, 0.654]). Conversely, a negligible Bayesian correlation was identified for squat (r=0.101, 95%CrI [-0.132, 0.319]), with substantial evidence favoring the null hypothesis (BF10=0.208). In conclusion, a positive correlation between MPV and SPV in deadlift during a CS-RT configuration, indicating potential utility for perceived velocity. However, velocity feedback prior SPV use and validity for squatting warrants further investigation. Keywords: Strength training, Perception, Powerlifting, Physical performance, Cluster training.

Exerting force at the maximal speed drives the increase in power output in elite athletes after 4weeks of resistance training.

In the present study, we examined how a 4-week intervention of maximal intended velocity (MIVRT) and controlled velocity resistance training (CRT)-induced task-specific responses in expert individuals. Twenty elite athletes were randomly assigned to either a MIVRT (n = 10) or CRT (n = 10) group, both following the same volume-load training based on the back-squat three times a week but with different intentions in moving load (force-exertion speed). We assessed one-repetition maximum (1RM), mean propulsive velocity (MPV), and mean propulsive power (MPP) using a progressive-loading test before and after the intervention. A linear position transducer was used to monitor propulsive velocity in training and testing sessions. Both groups significantly increased their 1RM (CRT: + 12.3%, p < 0.001, d = 0.39; MIVRT: + 12.5%, p < 0.001, d = 0.45). Only the MIVRT group showed a significant improvement in MPV (p < 0.01) across different stepping loads, while both groups improved in MPP (MIVRT: + 22.4%, p < 0.001, d = 0.54; CRT: + 8.1%, p = 0.04, d = 0.17). MIVRT induced significant adaptations in MPV and MPP at various loads (%1RM), underlining its specificity in targeting these parameters. Despite similar enhancements in 1RM, the distinct training protocols suggest that strength gains may stem from either maximal intent in moving loads or longer times under tension. This study highlights the role of execution speed in optimizing power outcomes, emphasizing task specificity as paramount to elicit physiological adaptations in chronically strength-trained individuals.

Analysis of Velocity, Power and Skin Temperature in Paralympic Powerlifting Athletes with Fixed and Variable Resistance.

To analyze the use of currents (VRT) and the traditional method (TRAD) on speed, power and temperature in a training session. Fourteen paralympic powerlifting (PP) athletes took part over three weeks. In week 1, familiarization and 1RM tests took place, and, in weeks 2 and 3, pre- and post-training took place, where the propulsive mean velocity and power and temperatures were assessed before and after, at 24 h and 48 h. There was a difference in the sternal pectoral temperatures before and after VRT (p = 0.040) and at 48 h for TRAD and VRT (p = 0.018); in the clavicular pectoralis before and after VRT and TRAD (p = 0.003); in the anterior deltoid after and at 48 h for TRAD and VRT (p = 0.026 and p = 0.017); and in the triceps after and at 24 h and 48 h between TRAD and VRT (p = 0.005). In the training series, the MPV was significant in TRAD between Set1 and Set5 (p = 0.003), in training (VRT) between Set1 and Set5 (p = 0.001) and in Set5 between the methods (p = 0.047). For power, there was a difference between Set1 and 5 in TRAD (p = 0.016) and VRT (p = 0.002). We conclude that training with currents (VRT) promoted greater muscle fatigue when compared to traditional training.

Optimizing resistance training intensity in supportive care for survivors of breast cancer: velocity-based approach in the row exercise.

Resistance training mitigates side effects during and after cancer treatment. To provide a new approach for precisely and safely assessing and prescribing the intensity of resistance training in supportive cancer care, the purpose of this study was to evaluate the load-velocity relationship during the row exercise in women survivors of breast cancer. Twenty women survivors of breast cancer who had undergone surgery and had completed core breast cancer treatment within the previous 10years completed an incremental loading test until the one repetition maximum (1RM) in the row exercise. The velocity was measured during the concentric phase of each repetition with a linear velocity transducer, and their relationship with the relative load was analyzed by linear and polynomial regression models. A strong relationship was observed between movement velocity and relative load for all measured velocity variables using linear and polynomial regression models (R2 > 0.90; SEE < 6.00%1RM). The mean velocity and mean propulsive velocity of 1RM was 0.40 ± 0.03m·s-1, whereas the peak velocity at 1RM was 0.64 ± 0.07m·s1. In women survivors of breast cancer, monitoring movement velocity during the row exercise can facilitate precise assessment and prescription of resistance training intensity in supportive cancer care.

The Impact of Exercise Order on Velocity Performance in the Bench Press and the Squat: A Comparative Study

We analyzed the influence of exercise order using the bench press and squat as the first or second exercise of the session on velocity performance. Ten male trained individuals (20.9 ± 0.7 years) randomly performed two protocols of three sets of six repetitions at 80% of their one-repetition maximum with different exercise sequences: the bench press followed by the squat (BP + S) and the squat followed by the bench press (S + BP). A linear velocity transducer attached to the Smith machine barbell measured the mean propulsive velocity (MPV), peak velocity (PV), and time to peak velocity. Additionally, blood lactate and heart rate were measured. Regarding the bench press, differences were found in the MPV in the first (BP + S: 0.50 ± 0.07 m·s−1 vs. S + BP: 0.42 ± 0.08 m·s−1; p = 0.03, g = 0.72) and second sets (0.50 ± 0.06 m·s−1 vs. 0.42 ± 0.07 m·s−1; p = 0.03, g = 0.73), and in the PV in the second set (0.74 ± 0.09 m·s−1 vs. 0.63 ± 0.09 m·s−1; p = 0.02, g = 0.86). Regarding the squat, although the S + BP sequence tended to show higher velocities, no significant differences were found between protocols. These results showed that squatting first decreased subsequent bench press velocity performance. On the other hand, squat velocity performance was not impaired when preceded by the bench press.

Influence of Grip Width on the Load-Velocity Relationship and 1 Repetition Maximum Value in the Bench Press Exercise: A Comparative and Reliability Analysis of Mean Velocity Vs. Mean Propulsive Velocity Vs. Peak Velocity.

Herrera-Bermudo, JC, Puente-Alcaraz, C, Díaz-Sánchez, P, González-Badillo, JJ, and Rodríguez-Rosell, D. Influence of grip width on the load-velocity relationship and 1 repetition maximum value in the bench press exercise: a comparative and reliability analysis of mean velocity vs. mean propulsive velocity vs. peak velocity. J Strength Cond Res XX(X): 000-000, 2024-This study aimed to analyze the reliability and compare the load (percentage of 1 repetition maximum [%1RM])-velocity relationship, bar displacement (DIS), the 1RM, and the velocity attained against the 1RM value (V1RM) in the bench press exercise using 3 different bar grip widths: narrow (120% of the biacromial distance [BD]), medium (160%), and wide (200%). A group of 54 healthy, physically active men randomly performed a total of 6 incremental tests (1 week apart) up to 1RM (2 with each bar grip width) on a Smith machine. The mean velocity (MV), mean propulsive velocity (MPV), peak velocity, and DIS were recorded for the subsequent analysis. The 3 velocity variables showed high relative (intraclass correlation coefficient: 0.90-0.97) and absolute (coefficient of variation: 2.21-9.38%) reliability in all grip widths against all relative loads. The 1RM value and the V1RM present high absolute and relative reliability in all grip widths. There are no significant differences in the value of 1RM and V1RM between grip widths. High relationships were observed between the relative load (%1RM) and velocity variables, with MPV showing the best fit. Significant greater values in MPV, MV, and DIS associated with each %1RM were observed for narrow and medium compared with wide grip width. In conclusion, our results suggest that the 3 velocity variables were highly reliable at the different grip widths used against all relative loads. In addition, there was a tendency to reach higher MV, MPV, and DIS values as the grip width decreased. Therefore, this factor should be considered for the assessment and design of training.

Direct measurement of self-diffusiophoretic force generated by active colloids of different patch coverage using optical tweezers

Hypothesis: Synthetic micro/nanomotors are gaining extensive attention for various biomedical applications (especially in drug delivery) due to their ability to mimic the motion of biological micro/nanoscale swimmers. The feasibility of these applications relies on tight control of propulsion speed, direction, and type of motion (translation, circular, etc.) along with the exerted self-propulsive force. We propose to exploit the variation of both self-propulsion speed and force of active colloids with different patch coverages (with and without supporting layer) for engineering diffusiophoretic micro/nanomotors.Experiments: The microswimmers were designed at various patch coverages (10°, 30°, and 90°) with (Ti/Pt) and without (Pt) an adhesion layer for the catalytic patch through glancing angle metal deposition (GLAD) technique. Mean-square displacement (MSD) analysis was performed to obtain the self-propulsion parameters like speed and angular speed. Using optical tweezers (OT), the self-propulsive force was measured from the force power spectral density.Findings: The findings of our experiments suggest the non-requirement of any adhesion layer preceding the catalyst deposition since the Pt 10° colloidal batch had the maximal self-propulsion speed (4.61±0.3μm/s) and force (345±57fN) for 5% w/v H2O2 fuel concentration. Moreover, the self-propulsion speed and force decreased with increasing patch size, contrary to theoretical estimates. Also, the self-propulsive force obtained from MSD is 2 to 4 times lower in magnitude than the OT based force values. We believe that the self-propelling motion of the micromotors is possibly hindered due to interactions with the surface of the quartz cuvette during the optical microscopic analysis. Further, the MSD is limited to the self-propulsive motion in two dimensions. On the other hand, OT based force measurement involve trapping the particles in the bulk of the solution entirely avoiding the particle–substrate interactions. Hence, OT based force measurements are better than the propulsion velocity based stokes drag force estimates. We believe that this study can lay the foundation in designing efficient micro/nanomotors for translational biomedical applications.

Acute Metabolic Response, Neuromuscular Activity, and Mechanical Performance to Different Set.

The aim of this study was to examine the acute metabolic response, neuromuscular activity, and mechanical performance of different set configurations in bench-press (BP). Twenty-two resistance-trained men performed three resistance exercise protocols consisting of 3 x 12 BP repetitions at 60% 1RM, with 4 minutes of rest between sets, but with different set configurations: (a) traditional set (TS), without rest within the set; (b) cluster-6 (CS6), with 30-second intraset rest after the sixth repetition in each set; and (c) cluster-2 (CS2), with 30-second intraset rest every two repetitions. Mean propulsive force (MPF), velocity (MPV), power (MPP), and electromyography (EMG) values were recorded for each repetition. Blood lactate, maximal voluntary isometric BP contraction, and dynamic strength in BP were assessed pre- and post-exercise. The CS2 protocol resulted in greater mechanical performance (i. e. MPF, MPV, and MPP) and lower alterations of EMG parameters (i. e. root mean square and median frequency) during the exercise compared to CS6 and TS (TS<CS6<CS2). The CS2 protocol induced smaller increases in lactate compared to TS and CS6. No significant "protocol x time" interactions were observed for the MVIC (maximal voluntary isometric BP contraction) variables. Introducing short but frequent intraset rest periods alleviates training-induced fatigue assessed by better performance maintenance.

Kinetic Predictors of Weightlifting Performance in Young Weightlifters.

Morris, SJ, Oliver, JL, Pedley, JS, Radnor, JM, Haff, GG, Cooper, S-M, and Lloyd, RS. Kinetic predictors of weightlifting performance in young weightlifters. J Strength Cond Res 38(9): 1551-1560, 2024-Relationships between force-generating capabilities and weightlifting performance ( e.g ., snatch, clean and jerk [C&J], and combined total) have previously been explored in adult weightlifters; however, associations in young athletes are unknown. The purpose of this study was twofold: (a) to examine the relationships between countermovement jump (CMJ) and isometric midthigh pull (IMTP) kinetics and weightlifting performance in young weightlifters and (b) to determine the proportion of weightlifting performance that could be accounted for by CMJ and IMTP kinetics using principal component analysis (PCA). Thirty-seven young weightlifters (12-18 years of age) completed 3 trials of CMJ and 2 trials of the IMTP assessments on dual force plates. Recent competition maximum loads, obtained within 2 weeks of the data collection, for the C&J and snatch were also recorded. Pearson's zero-order correlation coefficients demonstrated moderate to very high correlations ( r = 0.359-0.801; all p ≤ Benjamini-Hochberg critical values [ B-Hα ]) between CMJ kinetic variables, including jump height, average braking force, average braking velocity, absolute and relative braking net impulse, absolute and relative force at minimum displacement, absolute and relative propulsive force, absolute and relative propulsive net impulse and average propulsive velocity, and weightlifting performance. High to very high correlations were evident between IMTP peak force and relative peak force and all weightlifting performance metrics (snatch, C&J, combined total, combined total [kg]/body mass [kg -0.67 ], and Sinclair's total; r = 0.538-0.796; p ≤ B-Hα ). Components from the PCA were used to conduct stepwise, multiple, linear regression analyses. Moderate (45.8-52.9%) and large percentages (79.1-81.3%) of variance in absolute measures of weightlifting performance were explained by IMTP peak force variables and CMJ propulsive variables, respectively. These novel findings indicate that IMTP peak force variables and CMJ propulsive variables could provide valuable insight for talent identification and long-term athletic development in junior weightlifting pathways.

Load-Velocity Relationship in the Bulgarian Split-Squat Exercise.

Rabal-Pelay, J, Gutiérrez, H, Bascuas, P-J, Pareja-Blanco, F, and Marco-Contreras, LA. Load-velocity relationship in the Bulgarian split-squat exercise. J Strength Cond Res XX(X): 000-000, 2024-The objective of the current research was to analyze the load-velocity relationship in the Bulgarian split-squat (BSS) exercise and to compare these relationships between the dominant and nondominant legs. Twenty-one strength-trained men (age: 27.3 ± 7.3 years) performed a progressive loading test in the BSS exercise using a Smith machine for each leg. The protocol began with a load of 30 kg, incrementally adding 10 kg until the mean propulsive velocity (MPV) fell below 0.4 m·s-1. At that point, 5 kg increments were employed, with a final addition of 2.5 kg for the last estimated attempt one-repetition maximum (1RM). A total of 324 lifts were analyzed. Subjects exhibited a relative strength ratio of 1.23 ± 0.10, a 1RM of 91.3 ± 14.2 kg, and a mean range of motion of 44.7 ± 3.7 cm. Polynomial regression analysis showed a robust relationship with an R2 value of 0.945 (ρ ≤ 0.001) between the relative load (%1RM) and MPV. Despite the differences in 1RM between the dominant and nondominant legs, there were no significant differences in MPV at the %1RM between both legs. These findings suggest that training intensity can be prescribed via the MPV during the BSS exercise. Moreover, the load-velocity relationship is stable between limbs despite the potential differences in absolute strength levels.

Associations of strength indices and cycling economy in young adults

Abstract Objectives Cycling economy is associated with muscle strength in athletes. However, the relationship between strength capacity (i.e. maximal and explosive strength) and cycling economy in previously untrained but healthy individuals remains unclear. Therefore, this study aimed to assess the associations between cycling economy and strength performance in a population of recreationally active but untrained healthy individuals. Methods A total of 155 recreationally active individuals (95 males and 60 females) were included. Strength capacity was assessed through an incremental one-repetition maximum test, from which the one-repetition maximum, mean propulsive velocity, and mean propulsive power were derived as strength indices. Cycling economy was assessed using a step protocol on a cycle ergometer and gross oxygen cost and caloric unit cost were determined at submaximal intensities. Results Marginal R2 ranged between 0.013 and 0.062 for the gross oxygen cost and between 0.022 and 0.103 for the gross caloric unit cost, respectively. Greater cycling economy is related to higher strength levels. However, the relationship is relatively weak, explaining only 1.3–6.2 % of the variance in gross oxygen cost and 2.2–10.3 % of the variance in gross caloric unit cost. Conclusions Greater cycling economy in recreationally active males and females is related to higher strength levels (i.e. one-repetition maximum, mean propulsive velocity, mean propulsive power).

Load carriage does not reduce absolute mechanical power output but reduces agility in elite military police officers

Objectives. The main objective of this study was to evaluate mean propulsive velocity (MPV), mean propulsive force (MPF) and mean propulsive power (MPP) in elite police officers under LOADED and UNLOADED conditions. The study also investigated the association of body composition and strength levels under the same load conditions. Methods. Twenty-one men from an elite unit in Brazil participated in the study, performing Smith machine half squats and an agility test. Dual energy X-ray absorptiometry measured body composition; a linear encoder measured MPV, MPF and MPP during the half squats; and a manual chronometer registered agility test performance. Results. The results showed that wearing and carrying occupational loads did not alter the squat exercise’s MPP, MPV and MPF but reduced the performance of relative MPP and agility (p < 0.05). The results also showed that MPP had a higher association with force (i.e., MPF and one-repetition maximum [1RM]) than velocity (i.e., MPV and agility) under the LOADED condition (p < 0.05). Among the body composition variables, only lean body mass was associated with MPP under the LOADED condition (p < 0.05). Conclusion. These findings suggest that load carriage does not reduce absolute mechanical power output, but reduces the relative MPP and agility in military police officers.

Sex-related differences in the load-velocity and load-power relationships of the decline bench press exercise

ABSTRACT The purpose of this study was to analyse the load-velocity and load-power relationships of the decline bench press exercise (DBPE) and to compare sex-related differences. Twelve young healthy men and women performed a progressive loading test for the determination of 1RM strength and individual load-velocity and load-power relationship in the DBPE. A very close relationship between mean propulsive velocity (MPV) and %1RM was observed (R 2 = 0.94). This relationship improved when plotting data separately by sex (R 2 = 0.96–97). Individual load-velocity profiles gave an R 2 = 0.99 ± 0.01. The relationship between mean propulsive power (MPP) and %1RM was R 2 = 0.23. When separating data by sex, R 2 = 0.64–73 were obtained. Individual load-power profiles gave an R 2 of 0.93 ± 0.07. Significant sex-related differences were found for MPV, with males having faster velocities than females from 30% to 40% 1RM (p = 0.01) and for MPP, with males having greater MPP (W) than females from 30% to 95% 1RM (p < 0.001). The results of this study show that a strong correlation exists between relative load and MPV/MPP in the DBPE, allowing the possibility of using one to predict the other with great precision, especially when a sex-specific equation is used.

Monitoring Bar Velocity to Quantify Fatigue in Resistance Training.

We analyzed the effects of load magnitude and bar velocity variables on sensitivity to fatigue. Seventeen resistance-trained men (age=25.7±4.9 years; height=177.0±7.2 cm; body mass=77.7±12.3 kg; back-squat 1RM=145.0±33.9 kg; 1RM/body mass=1.86) participated in the study. Pre- and post-exercise changes in the mean propulsive velocity (MPV) and peak velocity (PV) in the back-squat at different intensities were compared with variations in the countermovement jump (CMJ). CMJ height decreased significantly from pre- to post-exercise (∆%=-7.5 to -10.4; p<0.01; ES=0.37 to 0.60). Bar velocity (MPV and PV) decreased across all loads (∆%=-4.0 to -12.5; p<0.01; ES=0.32 to 0.66). The decrease in performance was similar between the CMJ, MPV (40% and 80% 1RM; p=1.00), and PV (80% 1RM; p=1.00). The magnitude of reduction in CMJ performance was greater than MPV (60% 1RM; p=0.05) and PV (40% and 60% 1RM; p<0.01) at the post-exercise moment. Low systematic bias and acceptable levels of agreement were only found between CMJ and MPV at 40% and 80% 1RM (bias=0.35 to 1.59; ICC=0.51 to 0.71; CV=5.1% to 8.5%). These findings suggest that the back-squat at 40% or 80% 1RM using MPV provides optimal sensitivity to monitor fatigue through changes in bar velocity.

Enhancement of swimmer diffusion through regular kicks: analytic mapping of a scale-independent parameter space

Depending on their mechanism of self-propulsion, active particles can exhibit time-dependent, often periodic, propulsion velocity. The precise propulsion velocity profile determines their mean square displacement and their effective diffusion coefficient at long times. Here, we demonstrate that any periodic propulsion profile results in a larger diffusion coefficient than the corresponding case with constant propulsion velocity. We investigate, in detail, periodic exponentially decaying velocity pulses, expected in propulsion mechanisms based on sudden absorption of finite amounts of energy. We show, both analytically and with numerical simulations, that in these cases the effective diffusion coefficient can be arbitrarily enhanced with respect to the case with constant velocity equal to the average speed. Our results may help interpret, in a new light observations on the diffusion enhancement of active particles.