Peer Review #2 of "Effects of 12-week cadence retraining on impact peak, load rates and lower extremity biomechanics in running (v0.1)"

Background Excessive impact peak forces and vertical load rates are associated with running injuries and have been targeted in gait retraining studies. This study aimed to determine the effects of 12-week cadence retraining on impact peak, vertical load rates and lower extremity biomechanics during running. Methods Twenty-four healthy male recreational runners were randomised into either a 12-week cadence retraining group (n = 12), which included those who ran with a 7.5% increase in preferred cadence, or a control group (n = 12), which included those who ran without any changes in cadence. Kinematics and ground reaction forces were recorded simultaneously to quantify impact force variables and lower extremity kinematics and kinetics. Results Significantly decreased impact peak (1.86 ± 0.30 BW vs. 1.67 ± 0.27 BW, P = 0.003), vertical average load rates (91.59 ± 18.91 BW/s vs. 77.31 ± 15.12 BW/s, P = 0.001) and vertical instantaneous load rates (108.8 ± 24.5 BW/s vs. 92.8 ± 18.5 BW/s, P = 0.001) were observed in the cadence retraining group, while no significant differences were observed in the control group. Foot angles (18.27° ± 5.59° vs. 13.74° ± 2.82°, P = 0.003) and vertical velocities of the centre of gravity (CoG) (0.706 ± 0.115 m/s vs. 0.652 ± 0.091 m/s, P = 0.002) significantly decreased in the cadence retraining group at initial contact, but not in the control group. In addition, vertical excursions of the CoG (0.077 ± 0.01 m vs. 0.069 ± 0.008 m, P = 0.002) and peak knee flexion angles (38.6° ± 5.0° vs. 36.5° ± 5.5°, P < 0.001) significantly decreased whilst lower extremity stiffness significantly increased (34.34 ± 7.08 kN/m vs. 38.61 ± 6.51 kN/m, P = 0.048) in the cadence retraining group. However, no significant differences were observed for those variables in the control group. Conclusion Twelve-week cadence retraining significantly increased the cadence of the cadence retraining group by 5.7%. This increased cadence effectively reduced impact peak and vertical average/instantaneous load rates. Given the close relationship between impact force variables and running injuries, increasing the cadence as a retraining method may potentially reduce the risk of impact-related running injuries.

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Lower Extremity Biomechanics Predicts Major League Baseball Player Performance

Orthopaedic Journal of Sports Medicine ◽

10.1177/23259671211015237 ◽

2021 ◽

Vol 9 (7) ◽

pp. 232596712110152

Author(s):

Lucas G. Teske ◽

Edward C. Beck ◽

Garrett S. Bullock ◽

Kristen F. Nicholson ◽

Brian R. Waterman

Keyword(s):

Lower Extremity ◽

Major League Baseball ◽

Reaction Force ◽

Regression Trees ◽

Minimal Detectable Change ◽

Vertical Force ◽

Baseball Players ◽

Major League ◽

Lower Extremity Biomechanics ◽

Statistical Metrics

Background: Although lower extremity biomechanics has been correlated with traditional metrics among baseball players, its association with advanced statistical metrics has not been evaluated. Purpose: To establish normative biomechanical parameters during the countermovement jump (CMJ) among Major League Baseball (MLB) players and evaluate the relationship between CMJ-developed algorithms and advanced statistical metrics. Study Design: Cohort study; Level of evidence, 3. Methods: MLB players in 2 professional organizations performed the CMJ at the beginning of each baseball season from 2013 to 2017. We collected ground-reaction force data including the eccentric rate of force development (“load”), concentric vertical force (“explode”), and concentric vertical impulse (“drive”) as well as the Sparta Score. The advanced statistical metrics from each baseball season (eg, fielding independent pitching [FIP], weighted stolen base runs [wSB], and weighted on-base average) were also gathered for the study participants. The minimal detectable change (MDC) was calculated for each CMJ variable to establish normative parameters. Pearson coefficient analysis and regression trees were used to evaluate associations between CMJ data and advanced statistical metrics for the players. Results: A total of 151 pitchers and 138 batters were included in the final analysis. The MDC for “load,” “explode,” “drive,” and the Sparta Score was 10.3, 8.1, 8.7, and 4.6, respectively, and all demonstrated good reliability (intraclass correlation coefficient > 0.75). There was a weak but statistically significant correlation between the Sparta Score and wSB ( r = 0.23; P = .007); however, there were no significant correlations with any other advanced metrics. Regression trees demonstrated superior FIP with higher Sparta Scores in older pitchers compared with younger pitchers. Conclusion: There was a positive but weak correlation between the Sparta Score and base-stealing performance among professional baseball players. Additionally, older pitchers with a higher Sparta Score had statistically superior FIP compared with younger pitchers with a similar Sparta Score after adjusting for age.

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Do intermediate- and higher-order principal components contain useful information to detect subtle changes in lower extremity biomechanics during running?

Human Movement Science ◽

10.1016/j.humov.2015.08.018 ◽

2015 ◽

Vol 44 ◽

pp. 91-101 ◽

Cited By ~ 26

Author(s):

Angkoon Phinyomark ◽

Blayne A. Hettinga ◽

Sean Osis ◽

Reed Ferber

Keyword(s):

Lower Extremity ◽

Principal Components ◽

Higher Order ◽

Lower Extremity Biomechanics

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Lower-Extremity Biomechanics and Maintenance of Vertical-Jump Height During Prolonged Intermittent Exercise

Journal of Sport Rehabilitation ◽

10.1123/jsr.2013-0065 ◽

2014 ◽

Vol 23 (4) ◽

pp. 319-329

Author(s):

Randy J. Schmitz ◽

John C. Cone ◽

Timothy J. Copple ◽

Robert A. Henson ◽

Sandra J. Shultz

Keyword(s):

Lower Extremity ◽

Outcome Measures ◽

Principal Components ◽

Intermittent Exercise ◽

Vertical Jump ◽

The Body ◽

Rating Of Perceived Exertion ◽

Jump Height ◽

Lower Extremity Biomechanics ◽

Biomechanical Factors

Context:Potential biomechanical compensations allowing for maintenance of maximal explosive performance during prolonged intermittent exercise, with respect to the corresponding rise in injury rates during the later stages of exercise or competition, are relatively unknown.Objective:To identify lower-extremity countermovement-jump (CMJ) biomechanical factors using a principal-components approach and then examine how these factors changed during a 90-min intermittent-exercise protocol (IEP) while maintaining maximal jump height.Design:Mixed-model design.Setting:Laboratory.Participants:Fifty-nine intermittent-sport athletes (30 male, 29 female) participated in experimental and control conditions.Interventions:Before and after a dynamic warm-up and every 15 min during the 1st and 2nd halves of an individually prescribed 90-min IEP, participants were assessed on rating of perceived exertion, sprint/cut speed, and 3-dimensional CMJ biomechanics (experimental). On a separate day, the same measures were obtained every 15 min during 90 min of quiet rest (control).Main Outcome Measures:Univariate piecewise growth models analyzed progressive changes in CMJ performance and biomechanical factors extracted from a principal-components analysis of the individual biomechanical dependent variables.Results:While CMJ height was maintained during the 1st and 2nd halves, the body descended less and knee kinetic and energetic magnitudes decreased as the IEP progressed.Conclusions:The results indicate that vertical-jump performance is maintained along with progressive biomechanical changes commonly associated with decreased performance. A better understanding of lower-extremity biomechanics during explosive actions in response to IEP allows us to further develop and individualize performance training programs.

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