scholarly journals Associations between Well-Being State and Match External and Internal Load in Amateur Referees

2021 ◽  
Vol 18 (6) ◽  
pp. 3322
Author(s):  
Eñaut Ozaeta ◽  
Javier Yanci ◽  
Carlo Castagna ◽  
Estibaliz Romaratezabala ◽  
Daniel Castillo
Keyword(s):  
External Load ◽  
Contact Time ◽  
Well Being ◽  
Ground Contact ◽  
Internal Load ◽  
Match Play ◽  
Power Meter ◽  
Ground Contact Time ◽  
Training Impulse ◽  
External Loads

The main aim of this paper was to examine the association between prematch well-being status with match internal and external load in field (FR) and assistant (AR) soccer referees. Twenty-three FR and 46 AR participated in this study. The well-being state was assessed using the Hooper Scale and the match external and internal loads were monitored with Stryd Power Meter and heart monitors. While no significant differences were found in Hooper indices between match officials, FR registered higher external loads (p < 0.01; ES: 0.75 to 5.78), spent more time in zone 4 and zone 5, and recorded a greater training impulse (TRIMP) value (p < 0.01; ES: 1.35 to 1.62) than AR. Generally, no associations were found between the well-being variables and external loads for FR and AR. Additionally, no associations were found between the Hooper indices and internal loads for FR and AR. However, several relationships with different magnitudes were found between internal and external match loads, for FR, between power and speed with time spent in zone 2 (p < 0.05; r = −0.43), ground contact time with zone 2 and zone 3 (p < 0.05; r = 0.50 to 0.60) and power, speed, cadence and ground contact time correlated with time spent in zone 5 and TRIMP (p < 0.05 to 0.01; r = 0.42 to 0.64). Additionally, for AR, a relationship between speed and time in zone 1 was found (p < 0.05; r = −0.30; CL = 0.22). These results suggest that initial well-being state is not related to match officials’ performances during match play. In addition, the Stryd Power Meter can be a useful device to calculate the external load on soccer match officials.

scholarly journals External and internal training load relationships in soccer players: the metabolic power approach

2020 ◽  
Vol 45 ◽  
pp. 36-45
Author(s):  
Eser Çalı ◽  
Utku Alemdaroğlu
Keyword(s):  
External Load ◽  
High Speed ◽  
Training Load ◽  
Soccer Players ◽  
Metabolic Power ◽  
Internal Load ◽  
Total Distance ◽  
Metabolic Distance ◽  
Training Impulse ◽  
External Loads

The aim of the present study was to examine the relationships between internal training loads (TL) (Banister, Edwards Training-Impulse (TRIMP), session RPE (s-RPE)) and external TL (Total distance (TD), high speed distance (HSD), high metabolic distance (HMD) in amateur soccer players. Nine male amateur soccer players (age = 28.74±5.2 years; height 173.74± 8.04 cm; weight 72.73±5.5 kg) voluntarily participated in the study. Individual field-based training sessions were monitored over 8 weeks. The results showed that there were moderate and very large correlations between s-RPE and both Edwards and Banister’s TRIMP (respectively, r = 0.42-0.86; r= 0.45-0.85). Additionally, from large to nearly perfect correlations were observed between the HR-based methods (r= 0.58-0.98). We also found moderate to very large correlations between s-RPE and HMD and large to nearly perfect correlations between HR-based TL methods and HMD. Correlations between internal load and external load parameters was weaker in HSD than TD. In the light of the results of the current study, internal and external loads should not be used interchangeable and HMD seems to be appropriate to monitor TL in soccer players because its equations include both speed and acceleration values.

scholarly journals Validity of the Stryd Power Meter in Measuring Running Parameters at Submaximal Speeds

Sports ◽  
2020 ◽  
Vol 8 (7) ◽  
pp. 103
Author(s):  
Frank Imbach ◽  
Robin Candau ◽  
Romain Chailan ◽  
Stephane Perrey
Keyword(s):  
Motion Capture ◽  
Contact Time ◽  
Ground Contact ◽  
Spring Stiffness ◽  
Test Power ◽  
Power Meter ◽  
System A ◽  
Linear Relationships ◽  
Ground Contact Time ◽  
Recreational Runners

This study assessed the Stryd running power meter validity at sub-maximal speeds (8 to 19 km/h). Six recreational runners performed an incremental indoor running test. Power output (PO), ground contact time (GCT) and leg spring stiffness (LSS) were compared to reference measures recorded by portable metabolic analyser, force platforms and motion capture system. A Bayesian framework was conducted for systems validity and comparisons. We observed strong and positive linear relationships between Stryd PO and oxygen consumption ( R 2 = 0.82 , B F 10 > 100 ), and between Stryd PO and external mechanical power ( R 2 = 0.88 , B F 10 > 100 ). Stryd power meter underestimated PO ( B F 10 > 100 ) whereas GCT and LSS values did not show any significant differences with the reference measures ( B F 10 = 0.008 , B F 10 = 0.007 , respectively). We conclude that the Stryd power meter provides valid measures of GCT and LSS but underestimates the absolute values of PO.

Single-Leg Jump Performance Before and After Exercise in Healthy and Anterior Cruciate Ligament Reconstructed Individuals

2020 ◽  
Vol 29 (7) ◽  
pp. 879-885
Author(s):  
Haley Bookbinder ◽  
Lindsay V. Slater ◽  
Austin Simpson ◽  
Jay Hertel ◽  
Joseph M. Hart
Keyword(s):  
Anterior Cruciate Ligament ◽  
Repeated Measures ◽  
Contact Time ◽  
Cruciate Ligament ◽  
Ground Contact ◽  
Jump Height ◽  
Before And After ◽  
Healthy Control ◽  
Ground Contact Time ◽  
Anterior Cruciate

Context: Many clinicians measure lower-extremity symmetry after anterior cruciate ligament reconstruction (ACLR); however, testing is completed in a rested state rather than postexercise. Testing postexercise may better model conditions under which injury occurs. Objective: To compare changes in single-leg performance in healthy and individuals with history of ACLR before and after exercise. Design: Repeated-measures case-control. Setting: Laboratory. Patients: Fifty-two subjects (25 control and 27 ACLR). Intervention: Thirty minutes of exercise. Main Outcome Measures: Limb symmetry and involved limb performance (nondominant for healthy) for single-leg hop, ground contact time, and jump height during the 4-jump test. Cohen d effect sizes were calculated for all differences identified using a repeated-measures analysis of variance. Results: Healthy controls hopped farther than ACLR before (d = 0.65; confidence interval [CI], 0.09 to 1.20) and after exercise (d = 0.60; CI, 0.04 to 1.15). Those with ACLR had longer ground contact time on the reconstructed limb compared with the uninvolved limb after exercise (d = 0.53; CI, −0.02 to 1.09), and the reconstructed limb had greater ground contact time compared with the healthy control limb after exercise (d = 0.38; CI, −0.21 to 0.73). ACLR were less symmetrical than healthy before (d = 0.38; CI, 0.17 to 0.93) and after exercise (d = 0.84; CI, 0.28 to 1.41), and the reconstructed limb demonstrated decreased jump height compared with the healthy control limbs before (d = 0.75; CI, 0.19 to 1.31) and after exercise (d = 0.79; CI, 0.23 to 1.36). Conclusions: ACLR became more symmetric, which may be from adaptations of the reconstructed limb after exercise. Changes in performance and symmetry may provide additional information regarding adaptations to exercise after reconstruction.

scholarly journals The Relationships between Internal and External Load Measures for Division I College Football Practice

Sports ◽  
2020 ◽  
Vol 8 (12) ◽  
pp. 165
Author(s):  
Eric J. Sobolewski
Keyword(s):  
Heart Rate ◽  
External Load ◽  
Perceived Exertion ◽  
American Football ◽  
Division I ◽  
Football Players ◽  
Internal Load ◽  
Total Distance ◽  
Meaningful Relationships ◽  
Training Impulse

The aim of this study is to explore the relationships between internal and external load measures in American football. Thirty football players wore a portable integrated monitor unit for 10 weeks during the fall football season. Relationships between internal and external load measurements were determined. Internal load consisted of heart rate zones and heart rate-derived measures and session Ratings of Perceived Exertion (sRPE). External load consisted of distance in different speed zones, total distance traveled, and accelerations. There were many significant positive relationships, but the meaningful relationships (r > 0.5) were between heart rate-derived measures of load (Training Impulse and heart rate reserve) and low-intensity movement and total distance. Only accelerations between 1 and 1.99 m·s−2 were moderately correlated to heart rate-derived internal load. RPE values alone did not correlate strong enough with any of the measure but sRPE training load (sRPE-TL) correlated to most external values. Overall, moderate correlations were present between heart rate-derived internal load to total distance and lower intensity movement. sRPE-TL values had high correlations but were highly dependent on duration, not perceived exertion. When addressing load in American football, duration of the session is a key component in determining internal load as HR data and sRPE alone do not correlate highly with external loads.

External and internal Load and their Effects on Professional Volleyball Training

2020 ◽  
Vol 41 (07) ◽  
pp. 468-474
Author(s):  
Ricardo Franco Lima ◽  
Ana Silva ◽  
José Afonso ◽  
Henrique Castro ◽  
Filipe Manuel Clemente
Keyword(s):  
External Load ◽  
Inertial Measurement Unit ◽  
Perceived Exertion ◽  
Measurement Unit ◽  
Internal Load ◽  
Monitoring Process ◽  
Accurate Perception ◽  
Positive Correlations ◽  
The Impact ◽  
External Loads

AbstractThe purpose of this study was twofold: (i) characterize the external and internal training load of professional volleyball players with a focus on intra-week changes and (ii) test the relationships between internal and external load measures. Eight male professional players (age: 23.0±5.22 yo; body mass: 84.5 ± 7.58 kg; height: 193.0±9.71 cm; BMI: 22.0±0.02 kg/m2) were monitored daily over 15 weeks. The monitoring process included both internal (rate of perceived exertion [RPE] and session-RPE [s-RPE]) and external load variables, which were measured by an inertial measurement unit. Results revealed that, within-week variations revealed that RPE was significantly higher during MD-2 (d=0.59) and MD-3 (d=0.56) than MD-1. A significantly higher number of jumps was observed on MD-2 than MD-1 (d=0.69). Considering the relationships between internal and external load measures, small positive correlations were found between RPE and the number of jumps (r=0.17) and between s-RPE and the number of jumps (r=0.49). In conclusion, a tapering strategy was observed on the day before a match, as internal and external loads decreased. Both internal and external load measures are necessary to provide an accurate perception of the impact of training stimuli on players.

scholarly journals Sacral acceleration can predict whole-body kinetics and stride kinematics across running speeds

2021 ◽  
Author(s):  
Ryan Alcantara ◽  
Evan Day ◽  
Michael Hahn ◽  
Alena Grabowski
Keyword(s):  
Risk Factors ◽  
Contact Time ◽  
Injury Risk ◽  
Stress Fractures ◽  
Whole Body ◽  
Accelerometer Data ◽  
Ground Contact ◽  
Wearable Sensor ◽  
Ground Contact Time ◽  
Injury Risk Factors

Background. Stress fractures are injuries caused by repetitive loading during activities such as running. The application of advanced analytical methods such as machine learning to data from multiple wearable sensors has allowed for predictions of biomechanical variables associated with running-related injuries like stress fractures. However, it is unclear if data from a single wearable sensor can accurately estimate variables that characterize external loading during running such as peak vertical ground reaction force (vGRF), vertical impulse, and ground contact time. Predicting these biomechanical variables with a single wearable sensor could allow researchers, clinicians, and coaches to longitudinally monitor biomechanical running-related injury risk factors without expensive force-measuring equipment.Purpose. We quantified the accuracy of applying quantile regression forest (QRF) and linear regression (LR) models to sacral-mounted accelerometer data to predict peak vGRF, vertical impulse, and ground contact time across a range of running speeds.Methods. Thirty-seven collegiate cross country runners (24 females, 13 males) ran on a force-measuring treadmill at 3.8 – 5.4 m/s while wearing an accelerometer clipped posteriorly to the waistband of their running shorts. We cross-validated QRF and LR models by training them on acceleration data, running speed, step frequency, and body mass as predictor variables. Trained models were then used to predict peak vGRF, vertical impulse, and contact time. We compared predicted values to those calculated from a force-measuring treadmill on a subset of data (n = 9) withheld during model training. We quantified prediction accuracy by calculating the root mean square error (RMSE) and mean absolute percentage error (MAPE).Results. The QRF model predicted peak vGRF with a RMSE of 0.150 body weights (BW) and MAPE ± SD of 4.27 ± 2.85%, predicted vertical impulse with a RMSE of 0.004 BW*s and MAPE of 0.80 ± 0.91%, and predicted contact time with a RMSE of 0.011 s and MAPE of 4.68 ± 3.00%. The LR model predicted peak vGRF with a RMSE of 0.139 BW and MAPE of 4.04 ± 2.57%, predicted vertical impulse with a RMSE of 0.002 BW*s and MAPE of 0.50 ± 0.42%, and predicted contact time with a RMSE of 0.008 s and MAPE of 3.50 ± 2.27%. There were no statistically significant differences between QRF and LR model prediction MAPE for peak vGRF (p = 0.549) or vertical impulse (p = 0.073), but the LR model’s MAPE for contact time was significantly lower than the QRF model’s MAPE (p = 0.0497).Conclusions. Our findings indicate that the QRF and LR models can accurately predict peak vGRF, vertical impulse, and contact time (MAPE &lt; 5%) from a single sacral-mounted accelerometer across a range of running speeds. These findings may be beneficial for researchers, clinicians, or coaches seeking to monitor running-related injury risk factors without force-measuring equipment.

Shorter Ground Contact Time and Better Running Economy

2018 ◽  
Vol Publish Ahead of Print ◽  
Author(s):  
Martin Mooses ◽  
Diresibachew W. Haile ◽  
Robert Ojiambo ◽  
Meshack Sang ◽  
Kerli Mooses ◽  
...  
Keyword(s):  
Contact Time ◽  
Running Economy ◽  
Ground Contact ◽  
Ground Contact Time

Hopping frequency in humans: a test of how springs set stride frequency in bouncing gaits

1991 ◽  
Vol 71 (6) ◽  
pp. 2127-2132 ◽  
Author(s):  
C. T. Farley ◽  
R. Blickhan ◽  
J. Saito ◽  
C. R. Taylor
Keyword(s):  
Elastic Energy ◽  
Contact Time ◽  
The Body ◽  
Force Platform ◽  
Stride Frequency ◽  
Ground Contact ◽  
Muscular Force ◽  
Mass System ◽  
Ground Contact Time ◽  
The Cost

The storage and recovery of elastic energy in muscle-tendon springs is important in running, hopping, trotting, and galloping. We hypothesized that animals select the stride frequency at which they behave most like simple spring-mass systems. If higher or lower frequencies are used, they will not behave like simple spring-mass systems, and the storage and recovery of elastic energy will be reduced. We tested the hypothesis by having humans hop forward on a treadmill over a range of speeds and hop in place over a range of frequencies. The body was modeled as a simple spring-mass system, and the properties of the spring were measured by use of a force platform. Our subjects used nearly the same frequency (the “preferred frequency,” 2.2 hops/s) when they hopped forward on a treadmill and when they hopped in place. At this frequency, the body behaved like a simple spring-mass system. Contrary to our predictions, it also behaved like a simple spring-mass system when the subjects hopped at higher frequencies, up to the maximum they could achieve. However, at the higher frequencies, the time available to apply force to the ground (the ground contact time) was shorter, perhaps resulting in a higher cost of generating muscular force. At frequencies below the preferred frequency, as predicted by the hypothesis, the body did not behave in a springlike manner, and it appeared likely that the storage and recovery of elastic energy was reduced. The combination of springlike behavior and a long ground contact time at the preferred frequency should minimize the cost of generating muscular force.

scholarly journals NFL Draft Prep Players Improve 40-Yard Run Times and Foot-Ground Kinetics

2021 ◽  
Vol 1 (1) ◽  
Author(s):  
Monique Mokha ◽  
Tobin Silver ◽  
Pete Bommarito
Keyword(s):  
Contact Time ◽  
National Football League ◽  
Reaction Force ◽  
American Football ◽  
Football Players ◽  
Ground Contact ◽  
Vertical Ground Reaction Force ◽  
Linear Speed ◽  
Vertical Ground ◽  
Ground Contact Time

Introduction: Linear speed is a discriminant factor between drafted and undrafted American football players into the National Football League. Linear speed is influenced by foot-ground contact time and the magnitude of vertical ground reaction force. The aim of this study was to determine if foot-ground kinetics during speed running could be modified through participating in a 6-week NFL draft preparation camp. Methods:  To evaluate foot-ground kinetics, 16 American football players ran on an instrumented treadmill for 5 seconds at 6.5 m/s.  Linear speed was measured during a 40-yard (36.6 m) outdoor run. Pre- and post-camp linear speed times, stance-averaged vertical ground reaction forces (vGRF, kg/N), foot-ground contact time (msec), and vertical impulse (kg/N * s) were examined using paired t-tests, p<.05. Results: Linear speed times significantly improved [(pre, 4.8±0.2 vs. post, 4.6±0.2 sec), t(15)=13.8, p<.001)], and foot-ground contact time significantly decreased for the right limb [(pre, 177+3.2 vs. post, 168+2.2 ms), t(15)=2.21, p=.043]. Mean vertical impulse and stance-averaged GRF for both limbs remained unchanged, p>.05. Conclusions: Linear speed and selected foot-ground kinetics are modifiable in NFL draft prep players. Training appears to lower 40-yard run times and foot-ground contact time.

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