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Paul Comfort, Christopher Thomas, Thomas Dos’Santos, Paul A. Jones, Timothy J. Suchomel and John J. McMahon

produced during a squat jump (SJ) or a countermovement jump (CMJ) to PF during the IMTP has been discussed in the literature. 9 , 10 , 18 – 21 This ratio is commonly referred to as the Dynamic Strength Index (DSI) or the dynamic-strength deficit and has been reported to be highly reliable (intraclass

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Christopher Thomas, Paul A. Jones and Paul Comfort

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.

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Mark G.L. Sayers and Stephen Bishop

), intraclass correlation coefficients (ICC) and coefficient of variation (CV%) procedures. 24 The influence of medicine ball load on the various kinematic and dynamic strength variables were determined via a series of t -tests. Levene’s test for the homogeneity of variance was applied as part of the analyses

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Irineu Loturco, Lucas A. Pereira, Cesar C. Cal Abad, Saulo Gil, Katia Kitamura, Ronaldo Kobal and Fábio Y. Nakamura

Purpose:

To determine whether athletes from different sport disciplines present similar mean propulsive velocity (MPV) in the half-squat (HS) during submaximal and maximal tests, enabling prediction of 1-repetition maximum (1-RM) from MPV at any given submaximal load.

Methods:

Sixty-four male athletes, comprising American football, rugby, and soccer players; sprinters and jumpers; and combat-sport strikers attended 2 testing sessions separated by 2–4 wk. On the first visit, a standardized 1-RM test was performed. On the second, athletes performed HSs on Smith-machine equipment, using relative percentages of 1-RM to determine the respective MPV of submaximal and maximal loads. Linear regression established the relationship between MPV and percentage of 1-RM.

Results:

A very strong linear relationship (R 2 ≈ .96) was observed between the MPV and the percentages of HS 1-RM, resulting in the following equation: %HS 1-RM = −105.05 × MPV + 131.75. The MPV at HS 1-RM was ~0.3 m/s.

Conclusion:

This equation can be used to predict HS 1-RM on a Smith machine with a high degree of accuracy.

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Ecosse L. Lamoureux, Aron Murphy, Anthony Sparrow and Robert U. Newton

This study examined the effects of improved strength on an obstacle course (OC) simulating gait tasks commonly encountered by community-living older adults. Forty-five adults (mean age 68.2 ± 1.5 years) were randomly assigned to a control (10 women, 5 men) or an experimental group (EXP; 19 women, 10 men) and trained 3 days/week for 12 weeks. Using a 1-repetition-maximum (1-RM) method, 6 leg-strength measures were evaluated pre- and posttest. The times to walk an OC of 4 gait tasks (stepping over and across an obstacle, negotiating a raised surface, and foot targeting) set at 3 progressively challenging levels were also assessed. Significant Group × Time interactions were found on all 1-RM tests, with only EXP recording significant improvements (124–147%; p < .001). Strength gains in EXP were accompanied by significant improvements in the times to negotiate all gait stations and walk the entire OC (6-15%; p = .001–.014). This study showed that improving strength is an effective strategy to improve community locomotion, which might decrease the risks of falls in community-living older adults.

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Thaís Reichert, Rodrigo Sudatti Delevatti, Alexandre Konig Garcia Prado, Natália Carvalho Bagatini, Nicole Monticelli Simmer, Andressa Pellegrini Meinerz, Bruna Machado Barroso, Rochelle Rocha Costa, Ana Carolina Kanitz and Luiz Fernando Martins Kruel

risks and discomfort related to the tests prior to signing an informed consent form. After pretraining evaluations, the participants were allocated into 3 groups by stratified randomization ( randomization.com site) using a 1∶1∶1 ratio based on the maximum dynamic strength of knee extension. The groups

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Irineu Loturco, Lucas A. Pereira, Ciro Winckler, Weverton L. Santos, Ronaldo Kobal and Michael McGuigan

perform laborious and time-consuming maximum dynamic strength assessments. Further studies should be conducted to examine the force–velocity relationship in other Paralympic classes and sports, as well as to test these correlations in powerlifters without disabilities. Conclusions The load

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Aline C. Tritto, Salomão Bueno, Rosa M.P. Rodrigues, Bruno Gualano, Hamilton Roschel and Guilherme G. Artioli

composition, maximal dynamic strength, maximal voluntary isometric contraction (MVIC), muscle cross-sectional area (CSA), and food intake. The intervention consisted of a supervised resistance training program accompanied by supplementation with HMB-FA, HMB-Ca, or placebo (PL). MVIC and delayed onset muscle

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Mário C. Marques, Roland van den Tillaar, Jason D. Vescovi and Juan José González-Badillo

Purpose:

The purpose of this study was to examine the relationship between ball-throwing velocity during a 3-step running throw and dynamic strength, power, and bar velocity during a concentric-only bench-press exercise in team-handball players.

Methods:

Fourteen elite senior male team-handball players volunteered to participate. Each volunteer had power and bar velocity measured during a concentric-only bench-press test with 26, 36, and 46 kg, as well as having 1-repetition-maximum (1-RMBP) strength determined. Ball-throwing velocity was evaluated with a standard 3-step running throw using a radar gun.

Results:

Ball-throwing velocity was related to the absolute load lifted during the 1-RMBP (r = .637, P = .014), peak power using 36 kg (r = .586, P = .028) and 46 kg (r = .582, P = .029), and peak bar velocity using 26 kg (r = .563, P = .036) and 36 kg (r = .625, P = .017).

Conclusions:

The results indicate that throwing velocity of elite team-handball players is related to maximal dynamic strength, peak power, and peak bar velocity. Thus, a training regimen designed to improve ball-throwing velocity in elite male team-handball players should include exercises that are aimed at increasing both strength and power in the upper body.

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George Vagenas and T. Blaine Hoshizaki

The sprint starts of 15 skilled sprinters were filmed and their sprinting times recorded while they were performing four 20-meter sprinting trials. They employed their natural hand-block spacings with alternative leg placements in the front starting block. The subjects were tested for dynamic strength on a force platform and their stronger leg was determined. Selected qualitative variables concerning certain perceived characteristics of lateral dominance and preferred leg for some basic motor skills were identified using a questionnaire. Significantly greater takeoff velocities and faster sprinting times were found when the stronger leg was placed in the front block. Previous empirical methods used in determining the best front leg in the start were found unreliable. Even some experienced sprinters fail to use their optimal leg in the forward position. Dynamic lower limb strength asymmetry was established as the key determinant in optimizing leg placement in the sprint start.