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
Paul Comfort, Christopher Thomas, Thomas Dos’Santos, Paul A. Jones, Timothy J. Suchomel, and John J. McMahon
Marcelo Danillo Matos dos Santos, Felipe J. Aidar, Raphael Fabrício de Souza, Jymmys Lopes dos Santos, Andressa da Silva de Mello, Henrique P. Neiva, Daniel A. Marinho, and Mário C. Marques
. The study was carried out over 5 weeks, in the morning (9 AM–12 AM). The first one was used for familiarization with the maximal dynamic strength, maximal isometric strength (MIS), and surface electromyography (sEMG) experimental procedures. The evaluations occurred in the following weeks, on
Christopher Thomas, Paul A. Jones, and Paul Comfort
To determine the reliability of the Dynamic Strength Index (DSI) in college athletes.
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).
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.
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.
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
Irineu Loturco, Lucas A. Pereira, Tomás T. Freitas, Chris Bishop, Fernando Pareja-Blanco, and Michael R. McGuigan
distance traveled over a measured time interval. A 5-minute rest interval was allowed between the 2 attempts, and the fastest time was considered for subsequent analyses. Progressive Loading Test in the Half-Squat Exercise Maximum dynamic strength was assessed using the HS 1RM test, as described previously
Irineu Loturco, Lucas A. Pereira, Cesar C. Cal Abad, Saulo Gil, Katia Kitamura, Ronaldo Kobal, and Fábio Y. Nakamura
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.
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.
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.
This equation can be used to predict HS 1-RM on a Smith machine with a high degree of accuracy.
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.
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
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
Piia Kaikkonen, Esa Hynynen, Arto Hautala, and Juha P. Ahtiainen
strength (basal2). The basal measurements were performed to control the possible changes in strength performance during normal life, as no control group was included in the study. In addition to isometric strength, dynamic strength (1-repetition maximum [1-RM] leg press, leg press repetitions at 80% 1-RM