Validity and reliability of simple measurement device to assess the velocity of the barbell during squats

The Impact of Velocity-Based Training on Load-Velocity Relationships in Leg Press and Chest Press for Older Persons

ABSTRACT

Calaway, C, Mishra, S, Parrino, R, Martinez, KJ, Mann, JB, and Signorile, JF. Velocity-based training affects the load-velocity relationship in leg press and chest press for older persons. J Strength Cond Res 38(6): 1136-1143, 2024-This study examined the impact of 3 months of velocity-based training (VBT) on chest press (CP) and leg press (LP) maximal strength (1 repetition maximum [1RM]), peak power (PP), and percentage load where PP was achieved (%1RMPP) in older adults. Twenty-nine subjects were assigned to either a velocity-deficit (VD) group or a force-deficit (FD) group for each exercise depending on their load-velocity (LV) curves. Changes in load were determined by the ability to maintain either 90% (VD) or 70% (FD) of their PP during training. Subjects' powers were tested before and after the training intervention at loads between 40 and 80%1RM. Separate 2 (group) × 2 (time) ANOVA was used to examine changes in each variable by group for each exercise. Wilcoxon signed-rank tests were used to determine whether significant changes in %1RMPP for each exercise and group. For chest press 1 repetition maximum, there were no significant main effects or interaction. Significant main effects for time were observed for leg press 1 repetition maximum ( p < 0 .001, η2 = 0.547) and chest press peak power ( p = 0.009, η2 = 0.243). For LPPP, there were no significant main effects or interactions. For %1RMPP, CP median scores revealed no significant changes for either group. Significant declines in %1RMPP were observed for leg press velocity-deficit and leg press force-deficit ( p < 0.03) groups. Velocity-based training was effective at improving 1RM, PP, and shifting %1RMPP in the LP groups. These results have implications for targeting power improvements at specific areas of the LV curve. Health care providers and trainers should consider these findings when constructing exercise programs to counter age-related declines in older adults.

The validity of the Push Band 2.0 to determine speed and power during progressively loaded squat jumps

ABSTARCTThe PUSH band 2.0 is a wearable technology used to measure mean and peak velocity and power in strength-based movements. The agreement between the PUSH band 2.0 and the criterion measure (force plates) during progressively loaded squat jumps was assessed. Fifteen participants performed 3 squat jumps at increasing loads. Linear regression and Bland-Altman plots assessed data simultaneously recorded from both devices. Mean velocity and power showed deviation from the identity line and an overestimation of 7.40% and 25%, respectively. Peak velocity and power showed an overestimation of 14% and underestimation of 6%, respectively. The results support the use of Push Band 2.0 to measure velocity during ballistic squat movements. However, errors in power measurement are greater than acceptable to support in-field use. While peak velocity maintains a consistent overestimation bias across various velocities, mean velocity error increases at higher velocities and can only be considered valid at slow velocities.

Velocity-Based Strength Training: The Validity and Personal Monitoring of Barbell Velocity with the Apple Watch

Velocity-based training (VBT) is a method to monitor resistance training based on measured kinematics. Often, measurement devices are too expensive for non-professional use. The purpose of this study was to determine the accuracy and precision of the Apple Watch 7 and the Enode Pro device for measuring mean, peak, and propulsive velocity during the free-weighted back squat (in comparison to Vicon as the criterion). Velocity parameters from Vicon optical motion capture and the Apple Watch were derived by processing the motion data in an automated Python workflow. For the mean velocity, the barbell-mounted Apple Watch (r = 0.971-0.979, SEE = 0.049), wrist-worn Apple Watch (r = 0.952-0.965, SEE = 0.064) and barbell-mounted Enode Pro (r = 0.959-0.971, SEE = 0.059) showed an equal level of validity. The barbell-mounted Apple Watch (Vpeak: r = 0.952-0.965, SEE = 0.092; Vprop: r = 0.973-0.981, SEE = 0.05) was found to be the most valid for assessing propulsive and peak lifting velocity. The present results on the validity of the Apple Watch are very promising, and may pave the way for the inclusion of VBT applications in mainstream consumer wearables.

Development and Evaluation of a Full-Waveform Resistance Training Monitoring System Based on a Linear Position Transducer

Recent advances in training monitoring are centered on the statistical indicators of the concentric phase of the movement. However, those studies lack consideration of the integrity of the movement. Moreover, training performance evaluation needs valid data on the movement. Thus, this study presents a full-waveform resistance training monitoring system (FRTMS) as a whole-movement-process monitoring solution to acquire and analyze the full-waveform data of resistance training. The FRTMS includes a portable data acquisition device and a data processing and visualization software platform. The data acquisition device monitors the barbell's movement data. The software platform guides users through the acquisition of training parameters and provides feedback on the training result variables. To validate the FRTMS, we compared the simultaneous measurements of 30-90% 1RM of Smith squat lifts performed by 21 subjects with the FRTMS to similar measurements obtained with a previously validated three-dimensional motion capture system. Results showed that the FRTMS produced practically identical velocity outcomes, with a high Pearson's correlation coefficient, intraclass correlation coefficient, and coefficient of multiple correlations and a low root mean square error. We also studied the applications of the FRTMS in practical training by comparing the training results of a six-week experimental intervention with velocity-based training (VBT) and percentage-based training (PBT). The current findings suggest that the proposed monitoring system can provide reliable data for refining future training monitoring and analysis.

Sit-to-Stand Power Across the Lifespan: A Cross-Sectional Analysis

Lower-body power measured by a linear position transducer during the sit-to-stand (STS) movement declines with age and may be a predictor of physical disability in older adults. The purpose of this study was to establish normative data for STS power across the lifespan and to determine if differences exist between age cohorts, sexes, and age cohort-sex subgroups. Adults (N = 557) aged 18-89 were divided into five age cohorts and performed the STS connected to a linear position transducer, which calculated power and velocity during the movement. Significantly lower (p < .01) velocity was observed in a younger age cohort in females than males, whereas males saw a significant average power decrement (p < .01) in a younger age cohort than females. STS power norms give clinicians a metric predicting physical disability and may be of particular interest to males as their power production begins to decline at an earlier age.

Validity and Effects of Placement of Velocity-Based Training Devices

Velocity-based training (VBT) is a resistance training method by which training variables are manipulated based on kinematic outcomes, e.g., barbell velocity. The better precision for monitoring and manipulating training variables ascribed to VBT assumes that velocity is measured and communicated correctly. This study assessed the validity of several mobile and one stationary VBT device for measuring mean and peak concentric barbell velocity over a range of velocities and exercises, including low- and high-velocity, ballistic and non-ballistic, and plyometric and non-plyometric movements, and to quantify the isolated effect of device attachment point on measurement validity. GymAware (r = 0.90-1, standard error of the estimate, SEE = 0.01-0.08 m/s) and Quantum (r = 0.88-1, SEE = 0.01-0.18 m/s) were most valid for mean and peak velocity, with Vmaxpro (r = 0.92-0.99, SEE = 0.02-0.13 m/s) close behind. Push (r = 0.69-0.96, SEE = 0.03-0.17 m/s) and Flex (r = 0.60-0.94, SEE = 0.02-0.19 m/s) showed poorer validity (especially for higher-velocity exercises), although typical errors for mean velocity in exercises other than hang power snatch were acceptable. Effects of device placement were detectable, yet likely small enough (SEE < 0.1 m/s) to be negligible in training settings.

Validation of a Smartwatch-Based Workout Analysis Application in Exercise Recognition, Repetition Count and Prediction of 1RM in the Strength Training-Specific Setting

The goal of this study was to assess the validity, reliability and accuracy of a smartwatch-based workout analysis application in exercise recognition, repetition count and One Repetition Maximum (1RM) prediction in the strength training-specific setting. Thirty recreationally trained athletes performed four consecutive sets of barbell deadlift, barbell bench press and barbell back squat exercises with increasing loads from 60% to 80% of their estimated 1RM with maximum lift velocity. Data was measured using an Apple Watch Sport and instantaneously analyzed using an iOS workout analysis application called StrengthControl. The accuracies in exercise recognition and repetition count, as well as the reliability in predicting 1RM, were statistically analyzed and compared. The correct strength exercise was recognised in 88.4% of all the performed sets (N = 363) with accurate repetition count for the barbell back squat (p = 0.68) and the barbell deadlift (p = 0.09); however, repetition count for the barbell bench press was poor (p = 0.01). Only 8.9% of attempts to predict 1RM using the StrengthControl app were successful, with failed attempts being due to technical difficulties and time lag in data transfer. Using data from a linear position transducer instead, significantly different 1RM estimates were obtained when analysing repetition to failure versus load-velocity relationships. The present results provide new perspectives on the applicability of smartwatch-based strength training monitoring to improve athlete performance.

Comparison of Joint and Muscle Biomechanics in Maximal Flywheel Squat and Leg Press

The aim was to compare the musculoskeletal load distribution and muscle activity in two types of maximal flywheel leg-extension resistance exercises: horizontal leg press, during which the entire load is external, and squat, during which part of the load comprises the body weight. Nine healthy adult habitually strength-training individuals were investigated. Motion analysis and inverse dynamics-based musculoskeletal modelling were used to compute joint loads, muscle forces, and muscle activities. Total exercise load (resultant ground reaction force; rGRF) and the knee-extension net joint moment (NJM) were slightly and considerably greater, respectively, in squat than in leg press (p ≤ 0.04), whereas the hip-extension NJM was moderately greater in leg press than in squat (p = 0.03). Leg press was performed at 11° deeper knee-flexion angle than squat (p = 0.01). Quadriceps muscle activity was similar in squat and leg press. Both exercise modalities showed slightly to moderately greater force in the vastii muscles during the eccentric than concentric phase of a repetition (p ≤ 0.05), indicating eccentric overload. That the quadriceps muscle activity was similar in squat and leg press, while rGRF and NJM about the knee were greater in squat than leg press, may, together with the finding of a propensity to perform leg press at deeper knee angle than squat, suggest that leg press is the preferable leg-extension resistance exercise, both from a training efficacy and injury risk perspective.

Concurrent Validity of Field-Based Diagnostic Technology Monitoring Movement Velocity in Powerlifting Exercises

ABSTRACT

Mitter, B, Hölbling, D, Bauer, P, Stöckl, M, Baca, A, and Tschan, H. Concurrent validity of field-based diagnostic technology monitoring movement velocity in powerlifting exercises. J Strength Cond Res 35(8): 2170-2178, 2021-The study was designed to investigate the validity of different technologies used to determine movement velocity in resistance training. Twenty-four experienced powerlifters (18 male and 6 female; age, 25.1 ± 5.1 years) completed a progressive loading test in the squat, bench press, and conventional deadlift until reaching their 1 repetition maximum. Peak and mean velocity were simultaneously recorded with 4 field-based systems: GymAware (GA), FitroDyne (FD), PUSH (PU), and Beast Sensor (BS). 3D motion capturing was used to calculate specific gold standard trajectory references for each device. GA provided the most accurate output across exercises (r = 0.99-1, ES = -0.05 to 0.1). FD showed similar results for peak velocity (r = 1, standardized mean bias [ES] = -0.1 to -0.02) but considerably less validity for mean velocity (r = 0.92-0.95, ES = -0.57 to -0.29). Reasonably valid to highly valid output was provided by PU in all exercises (r = 0.91-0.97, ES = -0.5 to 0.28) and by BS in the bench press and for mean velocity in the squat (r = 0.87-0.96, ES = -0.5 to -0.06). However, BS did not reach the thresholds for reasonable validity in the deadlift and for peak velocity in the squat, mostly due to high standardized mean bias (ES = -0.78 to -0.63). In conclusion, different technologies should not be used interchangeably. Practitioners who require negligible measurement error in their assessment of movement velocity are advised to use linear position transducers over inertial sensors.

Validity and Reliability of the Inertial Measurement Unit for Barbell Velocity Assessments: A Systematic Review

The use of inertial measurement unit (IMU) has become popular in sports assessment. In the case of velocity-based training (VBT), there is a need to measure barbell velocity in each repetition. The use of IMUs may make the monitoring process easier; however, its validity and reliability should be established. Thus, this systematic review aimed to (1) identify and summarize studies that have examined the validity of wearable wireless IMUs for measuring barbell velocity and (2) identify and summarize studies that have examined the reliability of IMUs for measuring barbell velocity. A systematic review of Cochrane Library, EBSCO, PubMed, Scielo, Scopus, SPORTDiscus, and Web of Science databases was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. From the 161 studies initially identified, 22 were fully reviewed, and their outcome measures were extracted and analyzed. Among the eight different IMU models, seven can be considered valid and reliable for measuring barbell velocity. The great majority of IMUs used for measuring barbell velocity in linear trajectories are valid and reliable, and thus can be used by coaches for external load monitoring.

Using Field Based Data to Model Sprint Track Cycling Performance

Cycling performance models are used to study rider and sport characteristics to better understand performance determinants and optimise competition outcomes. Performance requirements cover the demands of competition a cyclist may encounter, whilst rider attributes are physical, technical and psychological characteristics contributing to performance. Several current models of endurance-cycling enhance understanding of performance in road cycling and track endurance, relying on a supply and demand perspective. However, they have yet to be developed for sprint-cycling, with current athlete preparation, instead relying on measures of peak-power, speed and strength to assess performance and guide training. Peak-power models do not adequately explain the demands of actual competition in events over 15-60 s, let alone, in World-Championship sprint cycling events comprising several rounds to medal finals. Whilst there are no descriptive studies of track-sprint cycling events, we present data from physiological interventions using track cycling and repeated sprint exercise research in multiple sports, to elucidate the demands of performance requiring several maximal sprints over a competition. This review will show physiological and power meter data, illustrating the role of all energy pathways in sprint performance. This understanding highlights the need to focus on the capacity required for a given race and over an event, and therefore the recovery needed for each subsequent race, within and between races, and how optimal pacing can be used to enhance performance. We propose a shift in sprint-cyclist preparation away from training just for peak power, to a more comprehensive model of the actual event demands.

Maximal Strength, Muscle Activation, and Bar Velocity Comparisons Between Squatting With a Traditional or Safety Squat Bar

ABSTRACT

Vantrease, WC, Townsend, JR, Sapp, PA, Henry, RN, and Johnson, KD. Maximal strength, muscle activation, and bar velocity comparisons between squatting with a traditional or safety squat bar. J Strength Cond Res 35(2S): S1-S5, 2021-The purpose of this study was to compare strength, muscle activation, and bar velocity between the traditional (TRAD) and safety squat bar (SSB) back squat. Thirty-two men (21.94 ± 3.1 years, 1.78 ± 0.8 m, 81.7 ± 10.1 kg) volunteered to complete this randomized, crossover-design study. Subjects completed 2 separate 1 repetition maximum (1RM) sessions using either the TRAD or SSB. Subsequently, subjects completed 1 session of 3 repetitions at 65 and 85% of their 1RM for each squat condition (SSB & TRAD). Peak muscle activation of 7 muscles from the lower body and trunk was recorded through surface electromyography (EMG), and mean velocity (MV) was recorded by a linear transducer. Electromyography and MV were analyzed by a 2 × 2 (bar × load) repeated-measures analysis of variance. A Pearson correlation was used to determine the relationship of 1RM load between bars. Squat 1RM was significantly higher (p < 0.001; 11.6%) for TRAD (144.7 kg) compared with SSB (128.8 kg), and a strong correlation (r = 0.94) was observed between 1RM values of each bar. A significant main effect was seen in EMG (p < 0.001) and MV for load (p < 0.001). No significant bar × load interaction was observed between conditions for any EMG or bar velocity measure (p > 0.05). The SSB produces similar muscle activation and bar velocities compared with the TRAD at relative intensities. However, absolute loads should be adjusted when changing squat bars during a training cycle.

The Validity and Reliability of Commercially Available Resistance Training Monitoring Devices: A Systematic Review

Background

Monitoring resistance training has a range of unique difficulties due to differences in physical characteristics and capacity between athletes, and the indoor environment in which it often occurs. Traditionally, methods such as volume load have been used, but these have inherent flaws. In recent times, numerous portable and affordable devices have been made available that purport to accurately and reliably measure kinetic and kinematic outputs, potentially offering practitioners a means of measuring resistance training loads with confidence. However, a thorough and systematic review of the literature describing the reliability and validity of these devices has yet to be undertaken, which may lead to uncertainty from practitioners on the utility of these devices.

Objective

A systematic review of studies that investigate the validity and/or reliability of commercially available devices that quantify kinetic and kinematic outputs during resistance training.

Methods

Following PRISMA guidelines, a systematic search of SPORTDiscus, Web of Science, and Medline was performed; studies included were (1) original research investigations; (2) full-text articles written in English; (3) published in a peer-reviewed academic journal; and (4) assessed the validity and/or reliability of commercially available portable devices that quantify resistance training exercises.

Results

A total of 129 studies were retrieved, of which 47 were duplicates. The titles and abstracts of 82 studies were screened and the full text of 40 manuscripts were assessed. A total of 31 studies met the inclusion criteria. Additional 13 studies, identified via reference list assessment, were included. Therefore, a total of 44 studies were included in this review.

Conclusion

Most of the studies within this review did not utilise a gold-standard criterion measure when assessing validity. This has likely led to under or overreporting of error for certain devices. Furthermore, studies that have quantified intra-device reliability have often failed to distinguish between technological and biological variability which has likely altered the true precision of each device. However, it appears linear transducers which have greater accuracy and reliability compared to other forms of device. Future research should endeavour to utilise gold-standard criterion measures across a broader range of exercises (including weightlifting movements) and relative loads.

Electronic supplementary material

The online version of this article (10.1007/s40279-020-01382-w) contains supplementary material, which is available to authorized users.

Concentric and eccentric inertia-velocity and inertia-power relationships in the flywheel squat

The aim of this study was to evaluate the effects of varying flywheel inertia on velocity and power during flywheel squats. Fifteen healthy physically active males performed 6 maximal effort flywheel half-squats at each of 0.029, 0.061, 0.089 and 0.121 kg·m², with velocity recorded via 3D motion capture and power recorded via inbuilt transducer. Peak concentric velocity (χ2 = 37.9; p < 0.001), peak eccentric velocity (χ2 = 24.9; p < 0.001), mean concentric velocity (F(3) = 52.7; p < 0.001) and mean eccentric velocity (χ2 = 16.8; p < 0.001) all tended to decrease with increases in flywheel inertia, whereas the ratio of peak eccentric to peak concentric power (F(3) = 4.26; p = 0.010) tended to increase. Flywheel inertia had no significant effect on peak concentric or eccentric power, or the ratio of eccentric to concentric peak or mean velocities. The best fit subject-specific inertia-velocity relationships were reported for peak concentric velocity (median linear R² = 0.95, median logarithmic R² = 0.97). The results suggest that velocity, rather than power, should be used to prescribe and monitor flywheel squat exercise intensities, and that individualized linear relationships between inertia and peak concentric velocity can be used for this purpose.

Construct Validity, Test-Retest Reliability, and Repeatability of Performance Variables Using a Flywheel Resistance Training Device

Bollinger, LM, Brantley, JT, Tarlton, JK, Baker, PA, Seay, RF, and Abel, MG. Construct validity, test-retest reliability, and repeatability of performance variables using a flywheel resistance training device. J Strength Cond Res 34(11): 3149-3156, 2020-Power production is highly associated with physical performance; however, the ability to quantitatively measure power output during resistance exercise is lacking. The purpose of this study was to determine the validity and test-retest reliability of flywheel-based performance testing. Twelve young, resistance trained subjects completed 2 bouts of resistance exercise using a flywheel resistance training device (Exxentric kbox 4 Pro). Each session consisted of 3 sets of 3 exercise (bent-over row, Romanian deadlift, and biceps curl) with varying moments of inertia (0.050, 0.075, and 0.100 kg·m, respectively) in random order. Each set consisted of 5 maximal effort repetitions with 3-minute recovery between sets. Average power, peak concentric and eccentric power, average force, average speed, and total work for each set were recorded. Regression analysis revealed a near-perfect relationship between measured and predicted power, force, and work at given workloads. Pearson's r between trials 1 and 2 revealed good (≥0.70) to excellent (≥0.90) test-retest reliability for all outcomes with the exception of peak eccentric power for biceps curls (r = 0.69), which narrowly missed the cutoff for acceptable reliability. Bland-Altman plots revealed small (approximately 5-15%), but statistically significant bias between the 2 trials for some measures. Coefficient of repeatability for all outcomes was relatively high, indicating poor repeatability. Flywheel-based performance testing provides valid data. However, reliability varies between individual lifts and specific outcomes. Given the poor repeatability between trials, it is likely that subjects who are unaccustomed to this modality may require multiple testing sessions or a thorough familiarization period to ensure accurate measures of power, force, speed, and work during flywheel-based performance testing.

Does Eccentric-only and Concentric-only Activation Increase Power Output?

PURPOSE

The aim of study was to evaluate changes in power output and bar velocity in the bench press throw (BPT) following the bench press (BP) exercise as a conditioning activity (CA) with concentric only (CONONLY) and eccentric only (ECCONLY) contractions.

METHODS

Thirty-two (n = 32) healthy strength-trained men participated in this study (age, 28.4 ± 4.5 yr; height, 177 ± 7.6 cm; body mass, 93.5 ± 9.3 kg; BP one-repetition maximum (1RM), 143.6 ± 17.5 kg). The experiment was performed following a randomized crossover design, where each participant performed 2 sets of 2 repetitions using the BP exercise as the CA at 90% 1RM ECCONLY, 90% 1RM CONONLY, 110% 1RM ECCONLY, or 130% 1RM ECCONLY contraction. The BPT was performed to assess changes in peak power (PP), mean power (MP), and peak velocity (PV), mean velocity (MV) before and after CA. The differences between analyzed variables before and after the CA were verified using ANOVA with repeated measures. Statistical significance was set at P < 0.05.

RESULTS

There were statistically significant differences between baseline and postactivation value of PP and PV in the BPT (P < 0.05) after the CA with ECCONLY contraction at 110% 1RM and at 130% 1RM as well between baseline and postactivation value of MV in the BPT (P < 0.05) after CA with contraction at 110% 1RM. There were no significant differences between baseline and postactivation values of PP, MP, PV, and MV in the BPT after the CA with CONONLY contraction at 90% 1RM and CA with ECCONLY contraction at 90% 1RM.

CONCLUSIONS

Partial movement with ECCONLY contraction is effective in short-term power output development, but only when the load used in the CA exceeds 100% 1RM.

CONCURRENT VALIDITY OF INSTRUMENTS FOR MEASURING SPEED OF MOVEMENT IN LEG PRESS EXERCISES

ABSTRACT Introduction Adequate measurement of movement velocity in strength exercises can assist in the prescription and evaluation of training effects. Objective The objectives of the present study were to analyze the reliability (test-retest) and concurrent validity of the movement velocity measured by means of the electrogoniometer and accelerometer during horizontal leg press exercise at different intensities (40, 60, 80% of a maximum repetition - 1RM). Methods Eighteen young women attended the laboratory on five occasions. After determining the maximum dynamic force, two visits (separated by 48-72 hours) were used to verify the reliability (test-retest) for different speed variables in the three intensities. Results The mean propulsive velocity obtained by the goniometer showed higher Intraclass correlation coefficients (ICC) and lower coefficients of variation compared to the accelerometer. The same behavior was observed for both the mean velocity and the peak velocity. The propulsive time was more reproducible and with less variation for the accelerometer and bad CCI for both sensors were observed at 60% of 1RM. When the sensors are compared, the mean and average propulsive velocities presented moderate ratios with a large to very large standardized medium bias. Conclusion The potentiometer of the electrogoniometer can be used to estimate the velocity in the horizontal leg press exercise, especially for loads of 60 and 80%. The performance of the accelerometer was inferior to that of the potentiometer. Level of evidence II; Diagnostic studies.

Reliability and Criterion Validity of the Assess2Perform Bar Sensei

The Assess2Perform Bar Sensei is a device used to measure barbell velocity for velocity-based training that has not yet been validated. The purpose of this study was to determine criterion validity and reliability of the Assess2Perform Bar Sensei in barbell back squats by comparing it against the GymAware PowerTool, a previously validated instrument. Sixteen injury-free, resistance-trained subjects (eleven males and five females) were recruited. Subjects were tested for their back squat one repetition maximum (1RM). Then, on two separate days, subjects performed two sets of three repetitions at loads of 45%, 60% and 75% 1RM. The GymAware PowerTool and Bar Sensei were attached to the barbell in similar locations for concurrent collection of mean concentric velocity (MCV) and peak concentric velocity (PCV). The Bar Sensei and PowerTool showed generally fair to poor agreement for MCV and PCV when subjects lifted 45% of 1RM (intraclass correlation;ICC 0.4–0.59), and they showed poor agreement when subjects lifted 60% and 75% of 1RM (ICC 0.3–0.4). Inter-repetition/within-set reliability for the Bar Sensei ranged between ICC = 0.273–0.451 for MCV and PCV compared to the far more reliable PowerTool (ICC = 0.651–0.793). Currently, the Bar Sensei is not a reliable or valid tool for measuring barbell velocity in back squats.

Validity and Reliability of Kinematics Measured with PUSH Band vs. Linear Encoder in Bench Press and Push-Ups

BACKGROUND

The aim of this study was to compare the validity and reliability of a PUSH band device with a linear encoder to measure movement velocity with different loads during the push-up and bench press exercises.

METHODS

Twenty resistance-trained athletes performed push-up and bench press exercises with four different loads: without weight vest, 10-20-30 kg weight vest, bench press: 50-82% of their assumed 1 repetition maximum (1 RM) in steps of 10 kg. A linear encoder (Musclelab) and the PUSH band measured mean and peak velocity during both exercises. Several statistical analyses were used to investigate the validity and reliability of the PUSH band with the linear encoder.

RESULTS

The main findings of this study demonstrated only moderate associations between the PUSH band and linear encoder for mean velocity (r = 0.62, 0.70) and peak velocity (r = 0.46, 0.49) for both exercises. Furthermore, a good level of agreement (peak velocity: ICC = 0.60, 0.64; mean velocity: ICC = 0.77, 0.78) was observed between the two measurement devices. However, a significant bias was found with lower velocity values measured with the PUSH band in both exercises. In the push-up, both the linear encoder and PUSH band were deemed very reliable (ICC > 0.98; the coefficient of variation (CV): 5.9-7.3%). Bench press reliability decreased for the PUSH band (ICC < 0.95), and the coefficient of variance increased to (12.8-13.3%) for the velocity measures. Calculated 1 RM with the two devices was the same for the push-up, while in bench press the PUSH band under-estimated the 1 RM by 14 kg compared to the linear encoder.

CONCLUSIONS

It was concluded that the PUSH band will show decreased reliability from velocity measures in a bench press exercise and underestimate load-velocity based 1 RM predictions. For training, the PUSH band can be used during push-ups, however caution is suggested when using the device for the purposes of feedback in bench press at increasing loads.

Reliability and Concurrent Validity of Seven Commercially Available Devices for the Assessment of Movement Velocity at Different Intensities During the Bench Press

Pérez-Castilla, A, Piepoli, A, Delgado-García, G, Garrido-Blanca, G, and García-Ramos, A. Reliability and concurrent validity of seven commercially available devices for the assessment of movement velocity at different intensities during the bench press. J Strength Cond Res 33(5): 1258-1265, 2019-The aim of this study was to compare the reliability and validity of 7 commercially available devices to measure movement velocity during the bench press exercise. Fourteen men completed 2 testing sessions. One-repetition maximum (1RM) in the bench press exercise was determined in the first session. The second testing session consisted of performing 3 repetitions against 5 loads (45, 55, 65, 75, and 85% of 1RM). The mean velocity was simultaneously measured using an optical motion sensing system (Trio-OptiTrack; "gold-standard") and 7 commercially available devices: 1 linear velocity transducer (T-Force), 2 linear position transducers (Chronojump and Speed4Lift), 1 camera-based optoelectronic system (Velowin), 1 smartphone application (PowerLift), and 2 inertial measurement units (IMUs) (PUSH band and Beast sensor). The devices were ranked from the most to the least reliable as follows: (a) Speed4Lift (coefficient of variation [CV] = 2.61%); (b) Velowin (CV = 3.99%), PowerLift (3.97%), Trio-OptiTrack (CV = 4.04%), T-Force (CV = 4.35%), and Chronojump (CV = 4.53%); (c) PUSH band (CV = 9.34%); and (d) Beast sensor (CV = 35.0%). A practically perfect association between the Trio-OptiTrack system and the different devices was observed (Pearson's product-moment correlation coefficient (r) range = 0.947-0.995; p < 0.001) with the only exception of the Beast sensor (r = 0.765; p < 0.001). These results suggest that linear velocity/position transducers, camera-based optoelectronic systems, and the smartphone application could be used to obtain accurate velocity measurements for restricted linear movements, whereas the IMUs used in this study were less reliable and valid.

Agreement between the Open Barbell and Tendo Linear Position Transducers for Monitoring Barbell Velocity during Resistance Exercise

To determine the agreement between the Open Barbell (OB) and Tendo weightlifting analyzer (TWA) for measuring barbell velocity, eleven men (19.4 ± 1.0 y) performed one set of 2–3 repetitions at four sub-maximal percentage loads, [i.e., 30, 50, 70, and 90% one-repetition maximum (1RM)] in the back (BS) and front squat (FS) exercises. During each repetition, peak and mean barbell velocity were recorded by OB and TWA devices, and the average of the 2–3 repetitions was used for analyses. Although the repeated measures analysis of variance revealed significantly (p ≤ 0.005) greater peak and mean velocity scores from OB across all intensities, high intraclass correlation coefficients (ICC_2,K = 0.790–0.998), low standard error of measurement (SEM_2,K = 0.040–0.119 m·s⁻¹), and coefficients of variation (CV = 2–4%) suggested consistency between devices. Positive (r = 0.491–0.949) Pearson correlations between averages and differences (between devices) in peak velocity, as well as associated Bland-Altman plots, showed greater differences occurred as the velocity increased, particularly at low-moderate intensity loads. OB consistently provides greater barbell velocity scores compared to TWA, and the differences between devices were more apparent as the peak velocity increased with low-to-moderate loads. Strength coaches and athletes may find better agreement between devices if the mean velocity scores are only considered.

Reproducibility and Repeatability of Five Different Technologies for Bar Velocity Measurement in Resistance Training

This study aimed to analyze the agreement between five bar velocity monitoring devices, currently used in resistance training, to determine the most reliable device based on reproducibility (between-device agreement for a given trial) and repeatability (between-trial variation for each device). Seventeen resistance-trained men performed duplicate trials against seven increasing loads (20-30-40-50-60-70-80 kg) while obtaining mean, mean propulsive and peak velocity outcomes in the bench press, full squat and prone bench pull exercises. Measurements were simultaneously registered by two linear velocity transducers (LVT), two linear position transducers (LPT), two optoelectronic camera-based systems (OEC), two smartphone video-based systems (VBS) and one accelerometer (ACC). A comprehensive set of statistics for assessing reliability was used. Magnitude of errors was reported both in absolute (m s^-1) and relative terms (%1RM), and included the smallest detectable change (SDC) and maximum errors (MaxError). LVT was the most reliable and sensitive device (SDC 0.02-0.06 m s^-1, MaxError 3.4-7.1% 1RM) and the preferred reference to compare with other technologies. OEC and LPT were the second-best alternatives (SDC 0.06-0.11 m s^-1), always considering the particular margins of error for each exercise and velocity outcome. ACC and VBS are not recommended given their substantial errors and uncertainty of the measurements (SDC > 0.13 m s^-1).

The "Journal of Functional Morphology and Kinesiology" Journal Club Series: Highlights on Recent Papers in Athletic Training

We are glad to introduce the tenth Journal Club. This edition is focused on several relevant studies published in the last years in the field of athletic training, chosen by our Editorial Board members and their colleagues. We hope to stimulate your curiosity in this field and to share with you the passion for the sport seen also from the scientific point of view. The Editorial Board members wish you an inspiring lecture.