Aortic stiffness increases during prolonged sitting independent of intermittent standing or prior exercise.

INTRODUCTION: Adverse vascular responses can occur during prolonged sitting, including stiffening of the aortic artery which may contribute to cardiovascular disease. Few studies have investigated the impact of intermittent standing and/or prior exercise as strategies to attenuate these potentially deleterious vascular changes. PURPOSE: To investigate central vascular health responses during prolonged sitting, with and without intermittent standing and/or prior exercise. METHODS: Fifteen males aged 18 to 31 years were recruited. Subjects completed a control condition [Sitting Only (SO)], and three randomized strategy conditions [Sitting Plus Standing (SSt), Exercise Plus Sitting (ES), Exercise Plus Sitting Plus Standing (ESSt)]. For all conditions, measurements of carotid-femoral pulse wave velocity (cfPWV) were taken at pre- and post-intervention, and brachial and central blood pressure (BP) at pre-, 1-h, 2-h, and 3-h intervention. RESULTS: cfPWV significantly increased from pre- to post-intervention for all conditions (all p ≤ 0.043), as did brachial mean arterial pressure (MAP) and diastolic BP, and central MAP and diastolic BP for the control condition (all p ≤ 0.022). Brachial and central systolic BP were significantly higher during SO compared to ESSt at 1 h, and compared to ES for central systolic BP (all p ≤ 0.036). CONCLUSIONS: Strategies of intermittent standing and/or prior exercise may not prevent aortic stiffening during sitting but may attenuate BP elevations in the brachial and aortic arteries. Future research should investigate causal mechanistic links between sitting and aortic stiffening, and other attenuation strategies.

Examining Countermovement Jump Strategies Between Women's NCAA Division I Sports.

ABSTRACT: Donahue, PT, Peel, SA, Rush, M, McInnis, AK, Littlefield, T, Calci, C, and Brutofsky, T. Examining countermovement jump strategies between women's NCAA Division I sports. J Strength Cond Res 37(10): 2052-2057, 2023-The purpose of this study was to examine countermovement vertical jump performance among female athletes who rely heavily on vertical jump performance within their given sport. Forty-five female athletes representing 3 teams (basketball, volleyball, and beach volleyball) competing at the NCAA Division I level completed 2 maximal effort countermovement jumps (CMJ) using a portable force platform. A 1-way analysis of variance was used to compare groups across each variable. Statistically significant differences were found between the groups regarding propulsive duration and time to takeoff with basketball showing the shortest time and beach volleyball having the longest times ( p < 0.05). In addition, differences were seen in countermovement depth and mean propulsive force between the groups with basketball displaying the smallest countermovement and highest force ( p < 0.05). No differences were seen in jump height and reactive strength index modified. Greater force and shorter durations in basketball athletes versus the low force and long durations in the beach volleyball athletes suggest that sporting backgrounds play a large role in how the CMJ is performed. This information can aid strength and conditioning practitioners in the design of training programs that are sport specific to the strategies used by the athlete.

Examination of Countermovement Jump Performance Changes in Collegiate Female Volleyball in Fatigued Conditions.

The purpose of this investigation was to examine changes in countermovement vertical jump performance after a single sport-specific training session in a sample of collegiate female volleyball athletes. Eleven NCAA Division I volleyball athletes performed countermovement vertical jumps with and without an arm swing prior to and immediately after a sport-specific training session. Each participant completed two jumps in each condition using a portable force platform. Paired samples t-tests were performed within each jump condition. When using an arm swing, mean braking force was the only variable to display a statistically significant change (p < 0.05). In the no-arm-swing condition, mean propulsive force, propulsive net impulse, jump height and reactive strength index modified all statistically increased (p < 0.05). Time to takeoff was statistically reduced (p < 0.05). Additionally, a single-subject analysis was performed across all eleven participants resulting in general trends seen in the no-arm-swing condition, whereas the arm-swing condition displayed inconsistent findings across participants.

Impact of acute caffeine ingestion on isometric squat and vertical jump performance.

BACKGROUND: Caffeine is the most widely used consumed ergogenic aid in athletic populations. With the raise in athlete monitoring protocols, caffeine usage may provide cause misinterpretation of monitoring data. Thus, the purpose of this investigation was to examine the potential impact of an acute dose of caffeine on vertical jump and isometric squat performance. METHODS: A single-blinded randomized crossover design of 12 (6 male and 6 female) recreationally trained participants was used. Each participant was given either a 400 mg dose of caffeine anhydrous or placebo condition 30 minutes prior to performing three trials of an isometric squat, countermovement vertical jump (CMJ), and squat jump (SJ) testing using a force platform. Mean values of the three trials were statistical compared between conditions using paired sample t-test for each variable of interest. RESULTS: Caffeine significantly increased peak force during the isometric squat (P=0.024). In the CMJ caffeine increased jump height (P=0.3), peak power (P=0.03), RSIm (P=0.001) and time to peak force (P=0.04). SJ mean force (P=0.04) and RSI (P=0.04) showed significant increases after caffeine consumption. CONCLUSIONS: This data suggests that caffeine affects the CMJ to a greater extent than the SJ. Furthermore, the variables that appear to be impacted during the CMJ, are those used commonly in protocols to assess the fatigue or readiness of athletes. Thus, the consumption of caffeine prior to monitoring protocols may negatively influence the interpretation of results and the subsequent prescription of training.

Association of anthropometrics and physical performance measures to golf-specific variables in collegiate male golfers.

BACKGROUND: As physical fitness has become more of a central component of competitive golf it is important to have an understanding of the relationship between anthropometric and physical performance on actual golf performance. Thus, the purpose of this investigation was to determine the relationship between measures of anthropometrics and physical performance to golf swing performance. METHODS: Fourteen division I collegiate golfers performed a battery of tests including the vertical jump, grip strength, rotational medicine ball toss, and sit and reach test in addition to anthropometric measure measurements. Golf specific variables included clubhead speed (CHS), ball velocity (BV) and carry distance (CD) using the participants own driver. Pearson product moment correlations were used to assess the level of relationship between all variables. RESULTS: Statistically significant large positive relationships were found between grip strength and all golf specific variables. Height also showed large significant positive relationship with both CHS and BV. CONCLUSIONS: The association between anthropometrics and physical performance and golf specific variables appear to be limited in a group of collegiate male golfers, outside of grip strength. However, this does not mean that physical fitness is irrelevant to golf performance, but caution should be taken in assuming increase in physical performance will have a direct impact on the golf specific variables.

Comparison of Countermovement and Squat Jumps Performance in Recreationally Trained Males.

The vertical jump has been shown to be an effective tool in assessing neuromuscular fatigue. The two most common iterations of the vertical jump are the countermovement and squat jumps. This investigation sought to identify if differences exist between the two jumping strategies with regard to electromyography (EMG) and kinetics in a group of recreationally trained males. Twenty-two participants completed one experimental session, where three countermovement (CMJ) and three squat jumps (SJ) were performed using a counterbalanced within-subject design. Jump performance was evaluated with data obtained using a force platform. Additionally, EMG was collected on the vastus lateralis (VL), vastus medialis (VM), semitendinosus (ST) and medial gastrocnemius (MG). Greater EMG values were seen in the CMJ for ST as well as percentage of activation in the MG (p < 0.05). Increased values of mean force and mean power were observed in the SJ, while the CMJ showed greater peak and mean velocity. Greater jump heights in the CMJ were present as well (p < 0.05). These findings suggest that the increase in CMJ jump height due to the increase in propulsive velocity is not due to increases in knee extensors muscle activation.

Impact of Hydration Status on Jump Performance in Recreationally Trained Males.

The vertical jump is commonly used as a means of evaluating athlete readiness. Athletes have been shown to arrive to training and competition in a hypohydrated state. Thus, this investigation sought to examine the impact of hydration status on both countermovement (CMJ) and squat jump (SJ) performance. Twenty-five recreationally trained males completed three CMJ and SJ in a euhydrated, hypohydrated and control condition. Conditions were separated by a minimum of 24 hours. Hydration status was assessed using urine specific gravity. Jump performance was evaluated using both kinematic and kinetic data obtained from a force platform. A repeated-measures ANOVA was performed for each variable of interest in both the CMJ and SJ. CMJ peak and mean force values were significantly greater in the euhydrated condition compared to the hypohydrated condition (p < 0.05), with no differences between the control condition and either experimental condition. SJ showed reductions in jump height, peak and mean velocity, peak and mean power and impulse from control and euhydrated conditions (p < 0.05). The findings of this investigation show that when performing jump testing, specifically SJ, that hydration status of the individual may impact commonly used variables to assess the readiness of the individual for a given day.

Motor adaption during repeated motor control testing: Attenuated muscle activation without changes in response latencies.

With repeated exposure to postural perturbations the human postural control system can adapt and create efficient strategies to counteract these perturbations. The Motor Control Test (MCT) is commonly used to elicit reactionary postural movements. Though this device has been assessed for possible learning effects and reliability of composite scores, yet no study has evaluated possible neuromuscular alterations repeated bouts might elicit. Twenty participants (age: 25 ±â€¯4.73 years; height: 183.8 ±â€¯8.5 cm; mass: 85.2 ±â€¯15.6 kg) volunteered and, following familiarization, performed five full-randomized MCTs over six testing sessions. The first five sessions occurred on consecutive days, with the sixth occurring two days later. Electromyography (EMG) was recorded on right lower extremity knee flexors and extensors, and ankle plantarflexors and dorsiflexors. Response latencies and Mean and RMS muscle activity were calculated and analyzed using 1 × 5 (within days) and 1 × 6 (across days) RM ANOVA. Decreases in muscle activation of proximal musculature were noted between days and trials within days, however these changes were not maintained after the two-day retention period. No differences were detected for MCT scores. These results suggest repeated MCT exposure modifies neuromuscular responses to maintain similar reaction time through a postural control strategy shift.