scholarly journals Dynamic Strength Index: Relationships with Common Performance Variables and Contextualization of Training Recommendations

2020 ◽  
Vol 74 (1) ◽  
pp. 59-70
Author(s):  
Timothy J. Suchomel ◽  
Christopher J. Sole ◽  
Christopher R. Bellon ◽  
Michael H. Stone
Keyword(s):  
Peak Power ◽  
Female Athletes ◽  
Training Stimulus ◽  
Monitoring Program ◽  
Collegiate Athletes ◽  
Dynamic Strength ◽  
Peak Force ◽  
Power Performance ◽  
Strength Index

Abstract The purposes of this study were to examine the relationships between dynamic strength index (DSI) and other strength-power performance characteristics and to contextualize DSI scores using case study comparisons. 88 male and 67 female NCAA division I collegiate athletes performed countermovement jumps (CMJ) and isometric mid-thigh pulls (IMTP) during a pre-season testing session as part of a long-term athlete monitoring program. Spearman’s correlations were used to assess the relationships between DSI and CMJ peak force, height, modified reactive strength index, peak power and IMTP peak force and rate of force development (RFD). Very large relationships existed between DSI and IMTP peak force (r = -0.848 and -0.746), while small-moderate relationships existed between DSI and CMJ peak force (r = 0.297 and 0.313), height (r = 0.108 and 0.167), modified reactive strength index (r = 0.174 and 0.274), and IMTP RFD (r = -0.341 and -0.338) for men and women, respectively. Finally, relationships between DSI and CMJ peak power were trivial-small for male (r = 0.008) and female athletes (r = 0.191). Case study analyses revealed that despite similar DSI scores, each athlete’s percentile rankings for each variable and CMJ force-time characteristics were unique, which may suggest different training emphases are needed. Based on the explained variance, an athlete’s IMTP performance may have a larger influence on their DSI score compared to the CMJ. DSI scores should be contextualized using additional performance data to ensure each individual athlete receives the appropriate training stimulus during different training phases throughout the year.

scholarly journals Changes in Dynamic Strength Index in Response to Strength Training

Sports ◽  
2018 ◽  
Vol 6 (4) ◽  
pp. 176 ◽  
Author(s):  
Paul Comfort ◽  
Christopher Thomas ◽  
Thomas Dos’Santos ◽  
Timothy Suchomel ◽  
Paul Jones ◽  
...  
Keyword(s):  
Strength Training ◽  
Collegiate Athletes ◽  
Dynamic Strength ◽  
Minimal Change ◽  
Peak Force ◽  
Effect Sizes ◽  
Strength Index ◽  
Countermovement Jump ◽  
Strength Based ◽  
Moderate Difference

The primary aim of this investigation was to determine the effects of a four-week period of in-season strength training on the dynamic strength index (DSI). Pre and post a four-week period of strength-based training, twenty-four collegiate athletes (age = 19.9 ± 1.3 years; height = 1.70 ± 0.11 m; weight 68.1 ± 11.8 kg) performed three isometric mid-thigh pulls and countermovement jumps to permit the calculation of DSI. T-tests and Cohen’s effect sizes revealed a significant but small (p = 0.009, d = 0.50) decrease in DSI post-training (0.71 ± 0.13 N·N−1) compared to pre-training (0.65 ± 0.11 N·N−1); however, when divided into high and low DSI groups, differential responses were clear. The low DSI group exhibited no significant or meaningful (p = 1.000, d = 0.00) change in DSI pre to post-training (0.56 ± 0.05 N·N−1, 0.56 ± 0.09 N·N−1, respectively), whereas the high DSI group demonstrated a significant and large decrease (p = 0.034, d = 1.29) in DSI pre to post-training (0.85 ± 0.05 N·N−1, 0.74 ± 0.11 N·N−1, respectively), resulting in a significant and moderate difference (p = 0.034, d = 1.29) in the change in DSI between groups. These results demonstrate that DSI decreases in response to strength training, as expected, due to an increase in isometric mid-thigh pull peak force, with minimal change in dynamic (countermovement jump) peak force.

Reliability of the Dynamic Strength Index in College Athletes

2015 ◽  
Vol 10 (5) ◽  
pp. 542-545 ◽  
Author(s):  
Christopher Thomas ◽  
Paul A. Jones ◽  
Paul Comfort
Keyword(s):  
College Athletes ◽  
Intraclass Correlation ◽  
Force Production ◽  
Dynamic Strength ◽  
Peak Force ◽  
Dynamic Force ◽  
Strength Index ◽  
Training Interventions ◽  
Change In The Mean ◽  
Change In Mean

Purpose:To determine the reliability of the Dynamic Strength Index (DSI) in college athletes.Method:Nineteen male college athletes performed the squat jump (SJ) and isometric midthigh pull (IMTP) to determine peak force, on 2 separate days. Reliability was assessed by intraclass correlation coefficient (ICC), typical error (TE), percentage change in the mean, smallest worthwhile change (SWC), and coefficient of variation (%CV).Results:Peak force for the SJ was 2137 ± 499 N and 2781 ± 435 N for the IMTP, resulting in a mean DSI of 0.78 ± 0.19. Peak forces in the SJ (ICC = .99, TE = 57.22 N, change in mean = 0.2%, SWC = 4.7%, CV = 2.6%) and IMTP (ICC = .95, TE = 104.22 N, change in mean = 0.5%, SWC = 3.1%, CV = 3.8%) were considered highly reliable between sessions. However, IMTP peak force was the only variable with an overall TE < SWC. The DSI was also highly reliable (ICC = .97, TE = 0.03, change in mean = −0.3%, SWC = 5.1%, CV = 4.6%) between sessions.Conclusion:This study demonstrates that peak force in the SJ and IMTP are reliable, resulting in a reliable assessment of dynamic-force-production capabilities via the DSI. The DSI may be used to guide individualized training interventions and monitor specific adaptations to training. Changes in SJ peak force, IMTP peak force, and DSI were >4.67%, 3.13%, and 5.13%, respectively, identifying meaningful changes in response to training or competition.

scholarly journals PREDICTING MAXIMAL COUNTERMOVEMENT JUMP HEIGHT FROM UPRIGHT AND SQUAT POSITIONS HEAD TITLE: UPRIGHT AND SQUAT MAXIMUM JUMP HEIGHT PREDICTORS

2021 ◽  
Vol 2 (2021) ◽  
pp. 3-16
Author(s):  
David N. Suprak ◽  
◽  
Tal Amasay ◽  
Keyword(s):  
Peak Power ◽  
Collegiate Athletes ◽  
Arm Movement ◽  
Peak Force ◽  
Rate Of Force Development ◽  
Jump Height ◽  
Countermovement Jump ◽  
Jump Performance ◽  
Force Development ◽  
Height Prediction

Introduction. Countermovement jump is common in sport and testing and performed from various starting positions. Little is known about effective contributors to maximal countermovement jump height from various starting positions. Purpose and Objectives. Determine effective jump height predictors and effect of starting position on countermovement jump height. Applied Methodology. Forty-nine collegiate athletes performed maximal height countermovement jumps from upright and squatting positions with arm movement. Several variables were calculated from kinetic data. Correlation and regression determined variables related to and predictive of jump height in both conditions. Paired t-tests evaluated differences in jump height. Achieved Major Results. Upright condition jump height positively correlated with peak force and power, eccentric and concentric impulses, and countermovement depth. Jump height prediction included peak force and power, and eccentric and concentric impulses. Squat condition jump height positively correlated with peak force and power, mean rate of force development, force generated at the beginning of propulsion, and concentric impulse. Jump height prediction equation included mean rate of force development, force at the beginning of propulsion, and peak power. Jump height was higher in the upright condition. Conclusions. Higher jumps are achieved from the upright position. Peak force, peak power, and concentric and eccentric impulses best contribute to upright jump height. Mean rate of force development, force at the beginning of propulsion, and peak power best predicted squat jump height. Limitations. We did not restrict arm movement, to encourage natural motion. Depth was not controlled, rather advising a comfortable depth. Subjects were recruited from various collegiate sports. Practical implications. Maximal jump height from various positions may be achieved through efforts to maximize jump peak power and increase musculotendinous loading in sport-specific starting positions. Originality/Value. This is the first study to explore the predictors of upright and squat countermovement jumps. These results can guide jump performance training.

Design and performance of deep well dewatering: a case study

1998 ◽  
Vol 35 (1) ◽  
pp. 81-95 ◽  
Author(s):  
D W Sargent ◽  
R D Beckie ◽  
G Smith
Keyword(s):  
Soil Mechanics ◽  
Data Gathering ◽  
Monitoring Program ◽  
Treatment Plant ◽  
Pumping Test ◽  
Observational Method ◽  
Design Development ◽  
Deep Well ◽  
And Performance

This paper reviews the process used to design the construction dewatering system at the Influent Pumping Station at Annacis Island Wastewater Treatment Plant. The design process followed the "observational method," as applied to soil mechanics by K. Terzaghi and set out by R.B. Peck in the Ninth Rankine Lecture. The design was based on a working hypothesis of behaviour anticipated under the most probable conditions identified in the data gathering and assessment program. The sensitivity of the design was evaluated by considering potentially unfavourable conditions evident in the available data. The design development included a review of monitoring feedback obtained during the pumping-well installation, a pumping test, and the dewatering system start-up. The monitoring program and review process are presented.Key words: dewatering, observational method, case study, pumping test.

scholarly journals Influence of Warm-Up Music Preference on Anaerobic Exercise Performance in Division I NCAA Female Athletes

2021 ◽  
Vol 6 (3) ◽  
pp. 64
Author(s):  
Corinne E. Meglic ◽  
Caroline M. Orman ◽  
Rebecca R. Rogers ◽  
Tyler D. Williams ◽  
Christopher G. Ballmann
Keyword(s):  
Perceived Exertion ◽  
Female Athletes ◽  
Recovery Period ◽  
Collegiate Athletes ◽  
Anaerobic Exercise ◽  
Division I ◽  
Total Work ◽  
Active Recovery ◽  
Mean Power ◽  
Warm Up

The purpose of this study was to investigate the effects of listening to preferred versus non-preferred warm-up music on anaerobic sprint performance in Division I NCAA female athletes. Female collegiate athletes (n = 14) were recruited for this study. In a counterbalanced, crossover study design, participants completed two separate visits, each with a different warm-up music condition: preferred (Pref) or non-preferred (Non-pref). During each visit, participants completed a 3 min standardized cycling warm-up at 50 Watts while listening to Pref or Non-pref music. Following this, participants completed 3 × 15 s Wingate Anaerobic Tests (WAnTs) with a 2 min active recovery period in between tests. Motivation to exercise was measured immediately following the warm-up (WU), WAnT1, WAnT2, and WAnT3. The rate of perceived exertion (RPE) was also measured after each WAnT. Each visit was separated by a minimal recovery period of 48 h. Mean power, total work, RPE, and motivation were analyzed. Mean power (p = 0.044; d = 0.91) and total work (p = 0.045; d = 0.78) were significantly higher during the Pref music condition versus Non-pref. RPE remained unchanged regardless of condition (p = 0.536; d = 0.01). Motivation was significantly higher with Pref warm-up music compared to Non-pref (p < 0.001; d = 1.55). These results show that listening to Pref warm-up music has an ergogenic benefit during repeated sprints in comparison to Non-pref music and improves motivation to exercise. Listening to warm-up music prior to high-intensity repeated exercise may aid in optimizing performance and training in collegiate athletes.

Impulse-Based Dynamic Strength Index

2021 ◽  
Vol Publish Ahead of Print ◽  
Author(s):  
Michael H. Haischer ◽  
John Krzyszkowski ◽  
Stuart Roche ◽  
Kristof Kipp
Keyword(s):  
Dynamic Strength ◽  
Strength Index

Force-velocity and force-power properties of single muscle fibers from elite master runners and sedentary men

1996 ◽  
Vol 271 (2) ◽  
pp. C676-C683 ◽  
Author(s):  
J. J. Widrick ◽  
S. W. Trappe ◽  
D. L. Costill ◽  
R. H. Fitts
Keyword(s):  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Power Output ◽  
Peak Power ◽  
Isometric Force ◽  
Peak Force ◽  
Peak Power Output ◽  
Type I ◽  
Shortening Velocity ◽  
Force Velocity

Gastrocnemius muscle fiber bundles were obtained by needle biopsy from five middle-aged sedentary men (SED group) and six age-matched endurance-trained master runners (RUN group). A single chemically permeabilized fiber segment was mounted between a force transducer and a position motor, subjected to a series of isotonic contractions at maximal Ca2+ activation (15 degrees C), and subsequently run on a 5% polyacrylamide gel to determine myosin heavy chain composition. The Hill equation was fit to the data obtained for each individual fiber (r2 > or = 0.98). For the SED group, fiber force-velocity parameters varied (P < 0.05) with fiber myosin heavy chain expression as follows: peak force, no differences: peak tension (force/fiber cross-sectional area), type IIx > type IIa > type I; maximal shortening velocity (Vmax, defined as y-intercept of force-velocity relationship), type IIx = type IIa > type I; a/Pzero (where a is a constant with dimensions of force and Pzero is peak isometric force), type IIx > type IIa > type I. Consequently, type IIx fibers produced twice as much peak power as type IIa fibers, whereas type IIa fibers produced about five times more peak power than type I fibers. RUN type I and IIa fibers were smaller in diameter and produced less peak force than SED type I and IIa fibers. The absolute peak power output of RUN type I and IIa fibers was 13 and 27% less, respectively, than peak power of similarly typed SED fibers. However, type I and IIa Vmax and a/Pzero were not different between the SED and RUN groups, and RUN type I and IIa power deficits disappeared after power was normalized for differences in fiber diameter. Thus the reduced absolute peak power output of the type I and IIa fibers from the master runners was a result of the smaller diameter of these fibers and a corresponding reduction in their peak isometric force production. This impairment in absolute peak power production at the single fiber level may be in part responsible for the reduced in vivo power output previously observed for endurance-trained athletes.

Analysis of Sport Orientation of Female Collegiate Athletes

1998 ◽  
Vol 86 (2) ◽  
pp. 647-650 ◽  
Author(s):  
Mel E. Finkenberg ◽  
F. Michael Moode ◽  
James M. DrNucci
Keyword(s):  
Women Athletes ◽  
Female Athletes ◽  
Collegiate Athletes ◽  
Control Group ◽  
Female Collegiate Athletes ◽  
Sport Orientation

Scores on three subscales of the Sport Orientation Questionnaire were analyzed to assess whether competitive orientation of 40 female athletes differed from that of 36 nonparticipants and whether competitive orientation differentiated among athletes participating in different sports. Intercollegiate women athletes from three sports (basketball = 12; Softball = 16; and volleyball = 12) and a control group of 36 women who did not participate in athletics were respondents. Scores on Win and Competition significantly discriminated among groups. Scores of the control group were significantly lower than those of each group of athletes. No other comparisons were significant.

Collegiate Athletes’ Gendered Perceptions of a Hypothetical Male and Female Coach

2010 ◽  
Vol 3 (1) ◽  
pp. 42-55
Author(s):  
Lori Rittenhouse-Wollmuth ◽  
Cindra S. Kamphoff ◽  
Jon Lim
Keyword(s):  
Female Athletes ◽  
Collegiate Athletes ◽  
Physical Contact ◽  
Head Coach ◽  
Male Athletes ◽  
Male And Female ◽  
Female Head ◽  
Study Results ◽  
Female Collegiate Athletes ◽  
Female Coaches

Historically, the world of sport is considered a masculine domain characterized by power, aggression, and physical contact (Hall, 1996). The exclusionary elements of the male culture of sport have created gender inequities in participation (Birrell & Theberge, 1994), and a gendered perception of male and female coaches (Frankl & Babitt, 1998; Weinberg, Reveles, & Jackson, 1984). The purpose of this study was to examine the perceptions of male and female collegiate athletes of a hypothetical male and female coach, and to determine if female coaches are more accepted compared to Weinberg et al.’s study investigating male and female athletes’ perceptions of a hypothetical coach. The Attitudinal Questionnaire (Weinberg, Reveles, & Jackson, 1984) was utilized to determine athletes’ attitudes about a hypothetical coach. A 2 × 2 MANOVA indicated a significant interaction between the gender of a hypothetical head coach and the gender of an athlete, and a significant main effect for gender. Univariate ANOVA results indicate that males and females differed in their attitudes and perceptions of both a hypothetical male and female head coach. The female athletes, compared to male athletes, were more likely to be accepting of coaches regardless of the coaches’ gender. Furthermore, male athletes were less accepting of female coaches. In addition, when comparing the means of the current study to Weinberg et al.’s (1984) study, results indicate that female coaches were not more accepted than in 1984.

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