Comparison of External Load across Multi-Day Tournaments in Female Youth Volleyball Athletes

Several youth volleyball tournaments are played across multiple consecutive days with athletes averaging 3–4 matches/day. This study evaluated the differences in workload of female youth volleyball athletes across days and by position during multi-day tournaments. Athletes (n = 22, 16.4 ± 0.4 years) wore an accelerometer during 12 two- and three-day tournaments. Workload was measured via kinetic energy (KE, J/lb), total jumps (TJ), high jumps (HJ, >51 cm), average jump height (cm), and percentage of high stress movements (%) via VERT accelerometers. Data were analyzed across days and by position as an average per day and analyzed via repeated measures analyses of variance. Across days, workload averages ranged 484.8–558.0 J/lb for KE, 27.3–31.2 TJ/match, 37.5–37.9 cm/jump, 5.2–6.5 HJ/match, and 20.1–20.7% high stress movements/match, with no difference (p = 0.300). Setters (49.2 ± 24.3 jumps) jumped more than liberos (13.0 ± 6.8 TJ, p = 0.005), and middles (45.8 ± 4.1 cm) jumped higher than all other positions (setters: 28.8 ± 3.6 cm, outside hitters: 41.3 ± 4.2 cm, and liberos: 27.0 ± 4.1 cm, p = 0.000–0.044). Athletes appeared to perform and recover sufficiently between days of play such that their external load was not affected. The level of competition tends to become more evenly matched as the tournament progresses, thus there may have been less physical demand early in the tournaments due to unequal competition levels compared to the final day of the tournament

Salivary C-Reactive Protein and Cortisol Analysis in Collegiate Female Lacrosse Athletes during a 2-Game Week

Cortisol (CORT) and C-reactive protein (CRP) are two indicators of stress and are linked to tissue inflammation and illness. Increased stress and inflammation have been shown to decrease cognitive functioning, leading to diminished performance for athletes. Subjectively, athletes indicate fluctuations in stress, but few studies have assessed the physiological response of training and competition in elite female athletes. PURPOSE: The primary aim was to assess the acute response of CORT and CRP in Division I female lacrosse athletes during a high-stress week, including two games and three practices during the competitive season. The secondary aim was to assess the relationships between the evening measures of CORT and CRP with objective workload measures. METHODS: Saliva samples were collected from the 14 Division I female lacrosse players each morning and evening over the course of a week during competition season. Days 2, 4, and 5 consisted of afternoon/evening (PM) practices lasting approximately two hours, with days 3 and 6 consisting of PM games. Day 1 was a resistance training day and day 7 was a rest day. Workload was measured using wearable global positioning system (GPS) units. Variables included were total distance (m), high-intensity distance (m, \u3e60% max sprint speed), sprints (count, \u3e90% max sprint speed), accelerations (count, \u3e3 m/s2), decelerations (count, \u3e3 m/s2), and sprint distance (m. \u3e 90% max sprint speed) RESULTS: CORT levels increased after the first game (0.36 ± 0.54 µg/dl) and peaked on the morning of Day 5 (1.03 ±0.08 µg/dl). The two significantly low CORT readings were observed in the morning on Day 3 (0.051±0.068 µg/dl) and on Day 4 PM (0.36 ± 0.48 µg/dl) (approximately 24 hours post-game collection, low workload day). Significantly higher salivary CORT concentrations were measured in the morning on Days 1 (0.61 ± 0.46 µg/dl), 5 (1.03 ±0.08 µg/dl), and 6 (0.76 ± 0.60 µg/dl). CRP levels fluctuated during the sampling period without a clear relationship to the game days. Significantly lower CRP salivary concentrations were seen in the morning on Day 5 (5.15 ± 4.03 pg/ml), and significantly higher CRP salivary concentrations on Days 2 (9.88 ± 2.83 pg/ml) and 3 PM (9.37 ± 3.72 pg/ml) (post-game, high workload). Repeated measures Pearson correlation analyses indicated trivial to low correlations between CORT and workload (r = 0.028 to 0.201, p = 0.167 to 0.847) and low correlations between CRP and workload (r = 0.182 to 0.274, p = .051 to 0.102). CONCLUSION: CRP and cortisol levels fluctuated greatly on a day-to-day basis. CRP tended to have a more direct response to load, with higher values directly after games. CORT values were less predictable in relation to workload and may therefore be affected by other factors such as academic load or the athlete’s personal life. Future research should consider the role of travel and academic load and their effects on CORT and CRP in a student athlete

Assessment of Relationships Between External Load Metrics and Game Performance in Women’s Lacrosse

International Journal of Exercise Science 15(6): 488-497, 2022. The purpose of this study was to analyse the relationship between external load metrics with game performance for Division I collegiate female lacrosse. Data were collected using microtechnology during 26 games with 13 athletes (attackers n = 5, midfielders n = 8). External load variables included: total distance (TD), distance rate (DR), high-intensity (HI) distance, speed, HI sprints, accelerations, decelerations, metabolic equivalent distance (MED), and sprints. For attackers, goals, points, shots, and shots on goal (SOG) had low, positive associations with TD (r = 0.32 to 0.42) and MED (r = 0.39 to 0.45). For midfielders, goals, shots, and draw controls had low, positive relationships with TD (r = 0.34 to 0.41), DR (r = 0.33 to 0.45), and decelerations (r = 0.30 to 0.35). Points and SOG had low associations with TD (r = 0.35), DR (r = 0.33), accelerations (r = 0.31), and decelerations (r = 0.32 to 0.35). Turnovers demonstrated low, positive relationships with HI distance (r = 0.31) and HI sprints (r = 0.41). Though the correlations were low, they still revealed insights into workload metrics and offensive game statistics in the sport of lacrosse. Training for attackers should focus on agility and a training base for TD. Training for midfielders should focus on HI endurance and sprinting

Salivary Cortisol Analysis in Collegiate Female Lacrosse Athletes

International Journal of Exercise Science 16(6): 242-251, 2023. Cortisol is a hormone that corresponds to physiological and emotional stress. The purpose of this study was to 1) evaluate the changes in cortisol in female Division I collegiate lacrosse players (n = 15) throughout the competitive season, and 2) evaluate the correlation between cortisol and athlete wellness and workload. Salivary cortisol samples were collected weekly in the morning throughout the entirety of the 2021 competitive season (12 weeks). Subjective athlete total wellness scores and sub-scores (muscle soreness, sleep quality, fatigue, and stress) were taken on the same days. Objective total weekly Athlete Load (AL, an amalgam workload metric) were tabulated from the previous training week. A significant effect of time was found on wellness (p \u3c 0.001) and AL (p \u3c 0.001) over the twelve weeks with weekly differences, such as weeks with more than one game, weeks with no games, weeks with students in quarantine (not competing), or weeks with academic stressors such as final exams. There were no weekly differences in cortisol (p = 0.058). Cortisol had negligible correlations with wellness (r = -0.010, p = 0.889) and AL (r = 0.083, p = 0.272) during the competitive season. These findings suggest that cortisol changed little for athletes throughout the season although training volume and wellness did. Thus, assessing acute responses of cortisol may prove to be more beneficial to evaluating athletes’ stress

Evaluation of Earbud and Wristwatch Heart Rate Monitors during Aerobic and Resistance Training

International Journal of Exercise Science 12(4): 374-384, 2019. Assessment of biometrics during exercise is evolving to create devices that are “all-inclusive , in an effort to decrease the number of devices required during exercise while providing comprehensive and accurate biometric measures. The purpose of this study was to determine the accuracy of two optical heart rate monitors, the Jabra earbud and the Mio Alpha wristwatch, during aerobic and anaerobic exercise. Twenty-two recreationally active participants (25.4 ± 6.9 years, 171 ± 11 cm, 73.9 ± 3.1 kg, and 25.2 ± 9.2% body fat) completed this study. Participants completed 30 minutes of treadmill activity, 25 minutes of high-intensity interval exercise (HIT), and 40 minutes of continuous outdoor activity of their choice, walking or running. Three heart rate (HR) monitors, (Polar chest strap, Mio Alpha, Jabra earbud) were worn during all exercises, with the Polar chest strap serving as the benchmark. HR was assessed in one-second intervals. Analyses included mean bias, mean absolute percent error (MAPE), and Lin’s concordance coefficient. Overall, the Mio Alpha had a MAPE of 5.73 ± 10.19% and a moderate correlation with the benchmark, r(c) = 0.771, performing better in the treadmill and outdoor conditions. The Jabra earbud had a MAPE of 3.14 ± 6.13%, and a high correlation with the benchmark, r(c) = 0.939, performing well in all three conditions. Placing a HR monitor in an earbud is a viable option for obtaining an accurate HR assessment during different types of exercise. The accuracy of the Mio Alpha was likely affected by wrist movements during the HIT training

Accuracy Assessment of a GPS Device for Maximum Sprint Speed

International Journal of Exercise Science 13(4): 273-280, 2020. Global positioning system (GPS) technology can capture maximum sprint speed (MSS) using fewer resources than electronic timing gates (ETG). Yet,errors with GPS technology are typically 1.01 km∙hr-1for instantaneous velocity, potentially limiting GPS accuracy. The purpose of this study was to compare MSS values obtained from GPS technology to those obtained from ETG. The MSS of 24 female athletes was determined using two tests that both began with a 20-m fly-in followed by: 1) 80-m maximal sprint with ETG placed at the start line, 30 m, 60 m, and 80 m, and 2) 30-m maximal sprint with ETG placed every 10 m. Sprint speed was calculated from each timing segment, and the fastest segment for each test was used for the calculated MSS. MSS was also obtained using a GPS unit measuring at 10 Hz. Mean bias and mean absolute percent error (MAPE) of the GPS was lower for the 80-m test (0.09 ± 1.24km∙hr-1,3.5 ±3.1%) than the 30-m test(1.58 ± 0.80 km∙hr-1, 5.5 ± 2.6%).Lin’s concordance agreement was found to be poor for both tests. The equivalence test indicated that the GPS was equivalent for both short and long distances, p\u3c .05, meaning the two results were within a 5% equivalence interval. The GPS devices were within the acceptable range of accuracy at short (10-m) and long (30-m) distances. These results can guide coaching staff regarding how to test their athlete’s metrics and the reliability of those results

The Effects of Warm-up Duration on Cycling Time Trial Performance in Trained Cyclists

. The purpose of this study was to assess the effects of three different warm-up condi-tions on a 5K cycling time trial (TT). Sixteen trained cyclists completed the study. At the first testing session, participants completed a maximal graded exercise test to assess maximal oxygen consumption (VO2max) and a familiarization of the TT. At three subse-quent visits, the participants completed the TT after no warm up, short warm-up of three minutes at 60% VO2max, or long warm-up of ten minutes at 60% VO2max. The warm-up was assigned in randomized order. VO2, heart rate (HR), lactate, power, and speed were assessed after the warm-up, 1K, and completion of the 5K TT. There was no dif-ference between type of warm-up for time, power, cadence, speed, VO2, HR, or lactate levels at the end of the TT. There was no significant difference between type of warm-up for time, VO2 or HR at the end of the 1K split. Warm-up length was not impactful on 5K TT performance or during the first km of the TT in trained cyclists. These results con-flict with previous evidence indicating that a warm-up in endurance events primarily improved VO2 kinetics at the onset of the exercise

Differences in Physiological Influences on Heart Rate Recovery between Trained and Untrained Adults

The purpose of this study was to evaluate differences in heart rate recovery (HRr) in trained and untrained adults, while assessing the role of physiological and emotional factors. Eighteen untrained and 21 trained participants completed a maximal exercise test and a 20-min treadmill exercise at 55–70% heart rate reserve, and emotional state was assessed prior to exercise. Multiple regression was used to assess relationships between heart rate recovery and physiological and emotional assessments. The trained group had a higher relative maximal oxygen consumption (p < 0.001), lower resting heart rate (p < 0.001), and faster short- and long-term heart rate recovery (p < 0.05) than the untrained group. Resting heart rate was the most predictive measure with HRr for the trained group (R = 0.551–0.818), whereas resting heart rate, maximal heart rate, and fitness were predictors of recovery in the untrained group (R = 0.764–0.977). The results show the predominant parasympathetic influence on HRr in the trained group, but indicates influence of fitness and exercise intensity on recovery in the untrained group. Thus, fitness appears to influence HRr in those only with low fitness. This notion may help influence the behavior of untrained individuals to improve fitness to reduce risk of mortality and morbidity

Peripheral Artery Disease and Activity-Induced Shifts in Quadriceps Median Frequency during Treadmill Walking: A Preliminary Study

Peripheral artery disease (PAD) is associated with altered gait biomechanics. No previous research study has investigated the effect of activity on muscle activation in individuals with PAD. The purpose of this study was to investigate the effect of PAD on muscle activation in response to a ten-minute walking task. METHODS: Ten healthy young adults, ten healthy older adults and ten individuals with PAD performed a ten-minute treadmill walking trial at a self-selected velocity. Surface EMG was recorded from the vastus lateralis and medial gastrocnemius during five steps in the first and tenth minutes of the walking trial. EMG signals were rectified and smoothed using the root mean squared (RMS) with a 20 ms smoothing window. Peak RMS EMG and median frequencies (MdF) were calculated. Mixed-model ANOVAs with Tukey&rsquo;s post-hoc was used to determine effects of group and activity on peak RMS EMG and MdF. RESULTS: PAD was associated with significantly greater reductions in MdF of the vastus lateralis compared to healthy young and healthy older adults. No significant differences were observed in peak RMS EMG. DISCUSSION: PAD is associated with exaggerated rates of fatigue in the quadriceps but not the gastrocnemius. Efficacy of evidence-based therapeutic interventions should be further investigated

Natural Supergravity inflation

We identify a new mechanism in supergravity theories which leads to successful inflation without any need for fine tuning. The simplest model yields a spectrum of density fluctuations tilted away from scale-invariance and negligible gravitational waves. We demonstrate that this is consistent with the observed large-scale structure for a cold dark matter dominated, critical density universe. The model can be tested through measurements of microwave background anisotropy on small angular scales.Comment: 14 pages (revtex) including 3 figures (epsf); Minor changes to Introduction and discussion and modified Figure 1; to appear in Phys. Lett. B; Postscript also available from ftp://ftp.physics.ox.ac.uk/pub/local/users/sarkar/SugraInfl.ps.g