The Influence of Countermovement Jump Protocol on Reactive Strength Index Modified and Flight Time: Contraction Time in Collegiate Basketball Players

Abstract

The purpose of the present investigation was to evaluate differences in Reactive Strength Index Modified (RSIMod) and Flight Time to Contraction Time Ratio (FT:CT) during the countermovement jump (CMJ) performed without the arm swing (CMJNAS) compared to the CMJ with the arm swing (CMJAS), while exploring the relationship within each variable between jump protocols. A secondary purpose sought to explore the relationship between RSIMod and FT:CT during both jump protocols. Twenty-two collegiate basketball players performed both three CMJNAS and three CMJAS on a force plate, during two separate testing sessions. RSIMod was calculated by the flight-time (RSIModFT) and impulse-momentum methods (RSIModIMP). CMJ variables were significantly greater during the CMJAS compared to CMJNAS (p < 0.001). There were large to very large correlations within each variable between the CMJAS and CMJNAS. There were significant positive correlations among RSIModFT, RSIModIMP, and FT:CT during both the CMJAS (r ≥ 0.864, p < 0.001) and CMJNAS (r ≥ 0.960, p < 0.001). These findings identify an increase in RSIMod or FT:CT during the CMJAS, that may provide independent information from the CMJNAS. In addition, either RSIMod or FT:CT may be utilized to monitor changes in performance, but simultaneous inclusion may be unnecessary.

Seasonal Variations in Game Activity Profiles and Players' Neuromuscular Performance in Collegiate Division I Basketball: Non-conference vs. Conference Tournament

“…Previous research has shown that loads imposed during training can elicit neuromuscular fatigue resulting in decreased JH and increased ground CT in elite basketball athletes (Edwards et al, 2018a , b ; Heishman et al, 2019 , 2020 ), as well as top level Australian Football (Cormack et al, 2008 , 2013 ) and Rugby League (McLean et al, 2010 ) using a CMJ. Despite the CMJ being the jump test most frequently found in the scientific literature (Edwards et al, 2018a , b ; Heishman et al, 2019 , 2020 ), the repeated-hop test was used herein and, hence, direct comparisons between studies must be performed with caution. However, the rebounding aspect of a repeat-hop test has an extremely high level of specificity as it relates to the sporting activity of basketball and that is the reason why the coaching staff opted to use this assessment throughout the season.…”

“…In fact, it has been suggested that the ability to produce high levels of force in short amounts of time is paramount and may differentiate basketballers from superior competition levels (Ziv and Lidor, 2010 ). For this reason, coaches and sport scientists have long been interested in the study of basketball game demands (McInnes et al, 1995 ; Abdelkrim et al, 2010a , b ; Sampaio et al, 2015 ; Puente et al, 2017 ; Ferioli et al, 2018 ; Svilar et al, 2018 , 2019 ; Vázquez-Guerrero et al, 2018 , 2019 ) and the players' neuromuscular profile (Caterisano et al, 1997 ; Gonzalez et al, 2013 ; Edwards et al, 2018a , b ; Heishman et al, 2019 , 2020 ). A deeper knowledge on these topics could have huge implications on the global responses relative to stress imposed by competition on, for example, players' jumping or reactive strength capabilities.…”

“…Conversely, Gonzalez et al ( 2013 ) observed that players who played more than ~25 min per game across an entire NBA season increased vertical jump power and improved their reaction time from pre- to post-season. Given these inconsistencies, more research is needed to better understand the fluctuation of neuromuscular performance parameters throughout the basketball season as it may provide valuable information regarding players' recovery needs and readiness to compete (McInnes et al, 1995 ; Abdelkrim et al, 2010b ; Puente et al, 2017 ; Neal et al, 2018 ; Vázquez-Guerrero et al, 2018 ; Heishman et al, 2019 , 2020 ; Svilar et al, 2019 ).…”

“…However, based on the need for rapid stretch shortening cycle actions in basketball, it may be interesting to explore a repeated-hop test to assess players readiness and fatigue levels during the competitive phase of the season (Klusemann et al, 2013 ). Variables obtained from this type of evaluation (e.g., peak force or reactive strength index [RSI]) can provide important information in sports that require the production of large amounts of vertical force in a short amount of time; moreover, they can reflect potential neuromuscular fatigue elicited by basketball competition (Cormack et al, 2008 , 2013 ; Gerodimos et al, 2008 ; McMahon et al, 2018 ; Heishman et al, 2019 , 2020 ).…”

The prediction of swim start performance based on squat jump force-time characteristics

“…The SJ trial with the highest jump height was kept for data analysis. Jump height was determined by the conventional impulse-momentum method (Jump Height = v 2 /2g, where v = velocity at take-off and g = gravitational acceleration) (Heishman et al, 2019). Ground reaction force data from the SJs were analysed using the commercially available ForceDecks software (ForceDecks, London, United Kingdom).…”