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

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.Conflicts of Interest The authors declare no conflict of interest. Funding This research received no external funding.Ye

Countermovement Jump Inter-Limb Asymmetries in Collegiate Basketball Players

The purpose of the present study was to establish the intrasession and intersession reliability of variables obtained from a force plate that was used to quantitate lower extremity inter-limb asymmetry during the bilateral countermovement jump (CMJ). Secondarily, a comparison was performed to determine the influence of the jump protocol CMJ with or without an arm swing (CMJ AS and CMJ NAS, respectively) on inter-limb asymmetries. Twenty-two collegiate basketball players performed three CMJ AS and three CMJ NAS on dual force platforms during two separate testing sessions. A majority of variables met the acceptable criterion of intersession and intrasession relative reliability (ICC > 0.700), while fewer than half met standards established for absolute reliability (CV < 10%). CMJ protocol appeared to influence asymmetries; Concentric Impulse-100 ms, Eccentric Braking Rate of Force Development, Eccentric Deceleration, and Force at Zero velocity were significantly di erent between jumping conditions (CMJAS versus CMJ NAS; p < 0.05). The present data establish the reliability and smallest worthwhile change of inter-limb asymmetries during the CMJ, while also identifying the influence of CMJ protocol on inter-limb asymmetries, which can be useful to practitioners and clinicians in order to e ectively monitor changes associated with performance, injury risk, and return-to-play strategies.Open Access fees paid for in whole or in part by the University of Oklahoma LibrariesYe

Comparing the Acute Effects of Intermittent and Continuous Whole-Body Vibration Exposure on Neuromuscular and Functional Measures in Sarcopenia and Nonsarcopenic Elderly Women

This investigation examined the acute effects of continuous whole-body vibration (CWBV) and intermittent whole-body vibration (IWBV) on neuromuscular and functional measures in women with sarcopenia and nonsarcopenic women. Continuous whole-body vibration was one 6-minute exposure, while IWBV consisted of six 60-second exposures to rest intervals (30 Hz, 2-4 mm amplitude). Factorial analyses revealed group × exposure × time interactions for jump height (JH; F = 10.8, P = .002), grip strength (GS; F = 15.5, P < .001), timed up and go test (F = 11.7, P = .002), and sit and reach test (S&R; F = 9.7, P = .004). Both JH and GS significantly improved post-WBV in women with sarcopenia (P < .001), with post-IWBV significantly greater (P < .001) than post-CWBV. Timed up and go test and S&R significantly improved post-IWBV in both the groups (P < .001) with post-IWBV significantly better than post-CWBV (P < .001). Bench press power at 20% one repetition maximum (1RM) revealed an exposure × time interaction (F = 4.6, P = .04) illuminating that IWBV significantly improved muscular power (P < .001). Bench press power at 40% 1RM revealed group × exposure (F = 6.4, P = .016) and exposure × time interactions (F = 5.8, P = .022). Individuals with sarcopenia significantly increased power output (P < .001) post-IWBV which was significantly greater than post-CWBV (P = .037). Bench press power at 60% 1RM revealed an exposure × time interaction (F = 8.6, P = .006), indicating that power was significantly improved post-IWBV (P = .027) and decreased post-CWBV. Berg Balance scale revealed a time main effect (F = 6.64, P = .015), and pain discomfort was significantly lower post-IWBV. These data indicate IWBV may provide a more efficacious exposure pattern in older women when compared to CWBV.The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article. Article processing charges funded in part by University of Oklahoma Libraries.YesTwo expert reviewers using single-blind process (reviewers' names and information is withheld from the authors). Established Ethics Policy with regards to who can review someone's work. The authors may nominate reviewers but the Editorial Board makes the final decision

Associations Between Two Athlete Monitoring Systems Used to Quantify External Training Loads in Basketball Players

Monitoring external training load (eTL) has become popular for team sport for managing fatigue, optimizing performance, and guiding return-to-play protocols. During indoor sports, eTL can be measured via inertial measurement units (IMU) or indoor positioning systems (IPS). Though each device provides unique information, the relationships between devices has not been examined. Therefore, the purpose of this study was to assess the association of eTL between an IMU and IPS used to monitor eTL in team sport. Retrospective analyses were performed on 13 elite male National Collegiate Athletic Association (NCAA) Division I basketball players (age: 20.2 ± 1.2 years, height: 201.1 ± 7.6 cm, mass: 96.8 ± 8.8 kg) from three practices during the off-season training phase. A one-way analysis of variance was used to test differences in eTL across practices. Pearson’s correlation examined the association between the Distance traveled during practice captured by IPS compared to PlayerLoad (PL), PlayerLoad per Minute (PL/Min), 2-Dimensional PlayerLoad (PL2D), 1-Dimensional PlayerLoad Forward (PL1D-FWD), Side (PL1D-SIDE), and Up (PL1D-UP) captured from the IMU. Regression analyses were performed to predict PL from Distance traveled. The eTL characteristics during Practice 1: PL = 420.4 ± 102.9, PL/min = 5.8 ± 1.4, Distance = 1645.9 ± 377.0 m; Practice 2: PL = 472.8 ± 109.5, PL/min = 5.1 ± 1.2, Distance = 1940.0 ± 436.3 m; Practice 3: PL = 295.1 ± 57.8, PL/min = 5.3 ± 1.0, Distance = 1198.2 ± 219.2 m. Significant (p ≤ 0.05) differences were observed in PL, PL2D, PL1D-FWD, PL1D-SIDE, PL1D-UP, and Distance across practices. Significant correlations (p ≤ 0.001) existed between Distance and PL parameters (Practice 1: r = 0.799–0.891; Practice 2: r = 0.819–0.972; and Practice 3: 0.761–0.891). Predictive models using Distance traveled accounted for 73.5–89.7% of the variance in PL. Significant relationships and predictive capacities exists between systems. Nonetheless, each system also appears to capture unique information that may still be useful to performance practitioners regarding the understanding of eTL.Open Access fees paid for in whole or in part by the University of Oklahoma Libraries.Ye

Monitoring External Training Loads and Neuromuscular Performance for Division I Basketball Players over the Preseason

Limited research has paralleled concomitant changes in external training load (eTL) and countermovement jump (CMJ) performance. Therefore, this investigation characterized eTL and CMJ performance changes across preseason training in Division 1 male collegiate basketball athletes, while examining the influence of position (Guard vs. Forward/Center) and scholarship status (Scholarship = S vs. Walk-on = WO). During 22 practices, eTL was monitored in 14 male athletes, with weekly CMJs performed to quantify neuromuscular performance (Jump Height [JH], Flight Time:Contraction Time [FT:CT], Reactive Strength Index Modified [RSIMod ]). PlayerLoad per minute was significantly higher during W1 and W2 (5.4 ± 1.3au and 5.3 ± 1.2au, respectively; p < 0.05) compared to subsequent weeks, but no additional differences in eTL parameters across time were observed. Scholarship athletes displayed greater PlayerLoad (S = 777.1 ± 35.6, WO = 530.1 ± 56.20; Inertial Movement Analysis (IMA) IMA_High (S = 70.9 ± 15.2, WO = 41.3 ± 15.2); IMA_Medium (S = 159.9 ± 30.7, WO = 92.7 ± 30.6); and IMA_Low (S = 700.6 ± 105.1, WO = 405 ± 105.0;) (p < 0.05), with no observed differences in eTL by position. Moderate decreases in FT:CT and RSIMod paralleled increased eTL. Significant increases in practice intensity (W1 and W2) did not impact CMJ performance, suggesting athletes could cope with the prescribed training loads. However, moderate perturbations in FT:CT and RSIMod paralleled the weeks with intensified training. Cumulatively, scholarship status appears to influence eTL while player position does not.The authors would like to thank Mr. Brady Brown and Mr. Keldon Peak for their assistance with this project. Additionally, the authors thank the Basketball Programs at the University of Oklahoma for their continued support of research directed at enhancing athlete performance, while also improving overall student-athlete welfare. Finally, the authors would also like to thank all of the student-athletes that graciously volunteered their time to enroll and participate in this study. The experiments comply with the current laws of the country in which they were performed. The authors have no conflict of interest to declare. Open Access fees paid for in whole or in part by the University of Oklahoma Libraries.Ye

Muscle Performance Changes with Age in Active Women

The purpose of this study was to examine age-related differences in muscle performance in women divided into young (YW, 20–39 years, n = 29) middle-aged (MAW, 40–59 years, n = 33), and older (OW, ≥60 years, n = 40) age groups. Methods: Hand grip strength, vertical jump performance, and knee extensor (KE) strength (0 deg/s, 60 deg/s, and 240 deg/s), speed of movement (SoM; at 1 Nm, 20%, 40%, and 60% isometric strength), and endurance (30-repetition test at 60 degs/s and 240 deg/s) were assessed. Computed tomography-acquired muscle cross-sectional area (mCSA) was measured and included to determine specific strength (KE strength/mCSA). Results: Hand grip strength was similar across groups, while jump performance declined with age (YW and MAW \u3e OW, p \u3c 0.001). KE strength declined significantly with age (all conditions p \u3c 0.01), while specific strength was similar across groups. SoM was significantly higher for YW and MAW compared to OW (both p \u3c 0.01). An age × velocity interaction revealed YW KE endurance was similar between conditions, whereas MAW and OW displayed significantly better endurance during the 60 deg/s condition. OW displayed impaired KE endurance at 240 deg/s (vs. YW and MAW, p \u3c 0.01) but improved at 60 deg/s (vs. YW, p \u3c 0.01). Dynamic torque decline increased with age (YW \u3c OW, p = 0.03) and was associated with intramuscular adipose tissue (r = 0.21, p = 0.04). Conclusions: Performance declines were most evident among OW, but few performance deficits had emerged in MAW. Interestingly, strength declines disappeared after normalizing to mCSA and endurance appears to be velocity-dependent

Acute and Chronic Effects of Whole-Body Vibration on Balance, Postural Stability, and Mobility in Women With Multiple Sclerosis

The acute and chronic effects of whole-body vibration (WBV) on balance, postural stability, and mobility were evaluated in 21 women with relapsing-remitting multiple sclerosis (MS) randomly assigned to control (n = 9) or experimental (n = 12) groups. To assess acute responses, outcome variables were assessed before and immediately after a session of WBV (five 30-second bouts of vibration; frequency 30 Hz; amplitude 3 mm; 1-minute rest intervals) during their first visit (week 1) using field (Timed-Up and Go; 500-m walk; Berg Balance Scale) and laboratory tests (NeuroCom Balance Master and EquiTest System—Sensory Organization Test, Adaptation Test, Limits of Stability, Modified Clinical Test for Sensory Integration of Balance, Unilateral Stance, Tandem Walk, Step/Quick Turn). Acute responses were also measured after their fifth visit for only the Adaptation and Sensory Organization tests. For the chronic responses, participants were exposed to the WBV protocol once a week, for a total of 5 weeks, and then at week 5, were reassessed with the Adaptation and the Sensory Organization tests. Neither acute nor chronic exposure to the WBV protocols used in this study resulted in significant improvements (P > .05) in balance, postural stability, or mobility as assessed by either field or laboratory tests. However, based on promising results from other studies that have used WBV with other clinical populations, either alone or in conjunction with exercise, additional studies that increase the dose of vibration exposure, both acutely and chronically, should be conducted in patients with MS.Declaration of Conflicting Interests The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article. Funding The author(s) received no financial support for the research, authorship, and/or publication of this article.Ye

Acute Neuromuscular and Endocrine Responses Following High and Low External Training Loads in Collegiate Basketball Players

INTRODUCTION: Elite athletes undergo aggressive training regimens containing strategically induced fatigue in an attempt to maximize adaptation and performance improvements to meet the individual demands of the various sport. Athlete monitoring strategies are often used to track training loads and subsequent changes in performance. Inertial measurement units are often utilized to quantify the external training loads (eTL), also known as the biomechanical or locomotive stress, during indoor team sport activities, while the countermovement jump (CMJ) is employed to evaluate acute neuromuscular fatigue and performance. Little data exist examining the dose response of eTL and subsequent change in neuromuscular fatigue and performance, especially in basketball players. Additionally, although the CMJ is a commonly used field measure, exploring specific alterations in the CMJ force-time characteristics rather than gross output measures has been proposed to provide more insight with regards to changes in neuromuscular fatigue and performance compared to only considering gross output parameters, however this is yet to be explored among basketball players. PURPOSE: Therefore, the purpose of this dissertation was to examine the acute neuromuscular function and endocrine responses to High versus Low eTL basketball practices in a cohort of collegiate basketball players. A secondary aim sought to examine if neuromuscular alteration were primary central or peripheral in origin in response to a sport-specific basketball training session. METHODS: This dissertation was divided into two parts. Part I included 16 NCAA Division I basketball players (Male = 12; Female = 4) that performed a High and Low eTL practice, in a cross-over study design, where practice intensity measured using IMUs and intensity was characterized by PlayerLoad/minute (PL/min). Prior to each practice, participants provided a salivary sample used to assess testosterone, cortisol, and Testosterone:Cortisol ratio, as well as performed 3 CMJs on a dual cell force platform. At the conclusion of each practice, participants provided another salivary sample and perform 3 more CMJs. Participants returned 24-hours following practice to provide another salivary sample and perform 3 more CMJs. Perceived fatigue and muscle soreness were assessed using subject recovery questionnaires prior to practice and 24-Hours following practice. Part II include 15 NCAA Division I basketball players (Male = 9; Female = 6) underwent neuromuscular performance assessments before, immediately-after, and 24-hours following a team practice. The eTL of each practice was captured using an IMU. Maximal voluntary contraction (MVC) and twitch responses to electrical neuromuscular stimulation were assessed during the isometric knee extensor contraction and at rest to measure central (voluntary activation) and peripheral (twitch torque) fatigue, as well as responses in twitch torque at rest were used examine the prevalence of low frequency fatigue. In addition, participants performed 3 CMJs at each time point to characterize neuromuscular fatigue and performance. STATISTICAL ANALYSIS: Data normality was confirmed using descriptive and graphical information supplemented by the Shapiro-Wilk test statistic. In Part I, a 2-way (Sex [male, female]) × Condition [high load, low load)] repeated measures (RM) analysis of variance (ANOVA), evaluate differences in eTL. Data from the recovery questionnaire exhibited a non-normal distribution, therefore the equivalent nonparametric test was utilized. Friedman's non-parametric test was used to test for significant differences in the median rank scores across the different conditions and time points. A 3-way (Sex [male, female] x Condition [high load, low load) x Time [pre-, immediately post, 24 hours-]) RM ANOVA was used to assess sex, condition, and time main effects, as well as the interaction between Sex, Condition, and Time for each CMJ variable. Additionally, a 2-way (Condition × Time) RM ANOVA was also used to evaluate Sex × Condition, Sex × Time, and Condition × Time interactions, with significant interactions examined using a post-hoc pairwise comparison with a Bonferroni correction to isolate simple effects. In Part II, an independent T-Test was used to evaluate differences in Training Loads during practice between sexes. A 2-way (Sex [male, female] × Time [Pre, 24 hours-post exercise]) was utilized to evaluate difference in Recovery questionnaire parameters, with post-hoc pairwise comparison using Bonferroni corrections used when a significant difference was detected. A 2-way (Sex [male, female] × Time [Pre, immediately post, 24 hours-post exercise]) RM ANOVA was used to examine Sex and Time main effects and the interaction between sex and time for each variable: CMJ variables, MVC, voluntary activation, twitch characteristics and Low frequency fatigue. If a significant Sex × Time interaction was verified, the statistical model was decomposed by examining the simple effects with separate one-way repeated measures ANOVAs with Bonferroni correction factors for each group and time point. For both Part I and Part II, statistical significance was set at p 0.05. When comparing three or more groups, partial eta-squared (ηp2) effect sizes were calculated and interpreted as small (0.0099), medium (0.0588) and large (0.1379). When comparing between two groups, Cohen’s d (d) effect sizes were utilized and interpreted as trivial (0–0.19), small (0.20–0.49), medium (0.50–0.79), and large (≥0.80). RESULTS: In Part I, there were significant differences in eTL during the High compared to the Low condition, including PlayerLoad per Minute and PlayerLoad (p 0.0.5) 4) In men, there were significant increases in testosterone from Pre to Post-Practice that returned to baseline at 24-hour following practice (p 0.05), but no differences in percent voluntary activation. CONCLUSIONS: These findings suggest High eTL practice evoke a small acute effect on CMJ variables immediately following practice, which resolve to baseline by 24-hours, whereas Low eTL seems to induce no alteration in CMJ performance. In men, practices stimulated acute increase in testosterone and cortisol, while no changes occurred in T:C ratio. Varying eTL did not influence these acute responses in testosterone and cortisol. In women, testosterone, cortisol, and T:C ratio remained unchanged by both High and Low eTLs. Sport-specific practice appears to increase MVC and central components of neuromuscular function (voluntary activation), especially 24-hours following the exposure. Only small signs of mild peripheral fatigue occur following practice, which included low frequency fatigue appear immediately after practice, but resolved by 24-hours following the practice exposure

Countermovement Jump Inter-Limb Asymmetries in Collegiate Basketball Players

The purpose of the present study was to establish the intrasession and intersession reliability of variables obtained from a force plate that was used to quantitate lower extremity inter-limb asymmetry during the bilateral countermovement jump (CMJ). Secondarily, a comparison was performed to determine the influence of the jump protocol CMJ with or without an arm swing (CMJ AS and CMJ NAS, respectively) on inter-limb asymmetries. Twenty-two collegiate basketball players performed three CMJ AS and three CMJ NAS on dual force platforms during two separate testing sessions. A majority of variables met the acceptable criterion of intersession and intrasession relative reliability (ICC &gt; 0.700), while fewer than half met standards established for absolute reliability (CV &lt; 10%). CMJ protocol appeared to influence asymmetries; Concentric Impulse-100 ms, Eccentric Braking Rate of Force Development, Eccentric Deceleration, and Force at Zero velocity were significantly different between jumping conditions (CMJAS versus CMJ NAS; p &lt; 0.05). The present data establish the reliability and smallest worthwhile change of inter-limb asymmetries during the CMJ, while also identifying the influence of CMJ protocol on inter-limb asymmetries, which can be useful to practitioners and clinicians in order to effectively monitor changes associated with performance, injury risk, and return-to-play strategies