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This study investigated chronic changes in cell free DNA (cf-DNA) and other biochemical markers throughout a college soccer season. Twenty three NCAA Division I male collegiate soccer players volunteered to participate in this study. Athletes were divided into two groups based upon their weekly average game time rating of session rating of perceived exertion (sRPE). Group 1 (G1, n = 13, age 21.7 ± 1.5 years, height 178.8 ± 6.9 cm, body mass 77.9 ± 6.5 kg), consisted mostly of starters, averaged greater than a weekly 1500 game time sRPE over a fifteen week Fall season. Group 2 (G2, n =10, age 20.6 ± 1.0 years, height 181.8 ± 7.4 cm, body mass 82.5 ± 10.5 kg) averaged less than 1500 game time sRPE. Venous blood samples were taken three times; preseason, approximately midseason and postseason. In G1, cf-DNA (P = 0.001), CRP (P = 0.000), CK (P = 0.003), cf-DNA %∆ (P = 0.002), CRP %∆ (P = 0.002), CK %∆ (P = 0.002) were all significantly higher than T1 at T2 and T3. In G2, CRP %∆ (P = 0.039) was significantly higher at T2 than T1. Despite the lack of statistically significant differences across all three testing times, cf-DNA %∆, CRP %∆ and CK %∆ increased throughout the season in G1. In G2, cf-DNA %∆, CRP %∆ and CK %∆ were all higher at T2 and T3 than T1 but fewer significant differences were present. This may suggest that cf-DNA is a useful marker to reflect accumulated soccer training and competitive stressors.

Purpose: The purpose of this investigation was to examine the effects of a submaximal running warm-up on running performance in male endurance athletes (n = 16, Mage = 21 ± 2 years, MVO2max = 69.3 ± 5.1 mL/kg/min). Method: Endurance performance was determined by a 30-min distance trial after control and submaximal running warm-up conditions in a randomized crossover fashion. The warm-up began with 5 min of quiet sitting, followed by 6 min of submaximal running split into 2-min intervals at speeds corresponding to 45%, 55%, and 65% maximal oxygen consumption (VO2max). A 2-min walk at 3.2 km/hr concluded the 13-min warm-up protocol. For the control condition, participants sat quietly for 13 min. VO2 and heart rate (HR) were determined at Minutes 0, 5, and 13 of the pre-exercise protocol in each condition. Results: At the end of 13 min prior to the distance trial, mean VO2 (warm-up = 14.1 ± 2.2 mL/kg/min vs. control = 5.5 ± 1.7 mL/kg/min) and mean HR (warm-up = 105 ± 11 bpm vs. control = 67 ± 11 bpm) were statistically greater (p < .001) in the warm-up condition compared with the control condition. The distance run did not statistically differ (p = .37) between the warm-up (7.8 ± 0.5 km) and control (7.7 ± 0.6 km) conditions; however, effect size calculation revealed a small effect (d = 0.2) in favor of the warm-up condition. Thus, the warm-up employed may have important and practical implications to determine placing among high-level athletes in close races. Conclusions: These findings suggest a submaximal running warm-up may have a small but critical effect on a 30-min distance trial in competitive endurance athletes. Further, the warm-up elicited increases in physiological variables VO2 and HR prior to performance; thus, a submaximal specific warm-up should warrant consideration.

INTRODUCTION: Monitoring an athlete’s psychological, physiological, and performance level is important when preparing for a major competition. No study to date has tracked a high-level weightlifter peaking for a major competition all the way up to the day of competition. Assessing performance at a competition is vital to ascertain if the athlete has reached a peaked and if peak performance will actually be expressed during the competition. PURPOSE: Therefore, the purpose of this study was to determine when peak jumping performance was achieved and whether psychological or physiological variables explained any jump performance changes in a high-level female weightlifter preparing for a national competition. We hypothesized that jumping performance would peak on competition day corresponding with improved recovery and stress states and preserved muscle cross-sectional area (CSA) relative to baseline values. METHODS: A USA national-level female weightlifter (23.5y; 54.0±0.6kg; 155.4cm) participated in this investigation. Laboratory testing was carried out over a 7-month period as part of an ongoing long-term athlete monitoring program. At 11-weeks out, testing was administered twice a week for each week leading up to competition, at the competition, and returning from the competition. Each testing session evaluated body mass, recovery-stress inventories using the short recovery and stress scale (SRSS), and vastus lateralis CSA via ultrasonography followed by a standardized warm-up preceding unloaded squat jumps (SJ) performed on dual force plates sampling at 1kHz. Hopkin’s effects size (ES) classifications for each data point was used to determine the potential magnitude of change observed for each test relative to baseline values. The smallest worthwhile change was used to determine a meaningful change relative to baseline values. This typical error and smallest worthwhile change were used to quantify the probability (i.e., precision) of performance change that took place. Values greater or less than baseline values with precision >95% signified a very likely change for each testing session relative to the competition. RESULTS: Weightlifting performance goals were met for the national championship (snatch=67kg, clean and jerk=92kg, total=159kg). Jumping performance (precision=99%,ES=2.7) was almost certainly peaked on competition day with increased recovery (ES=0.7) and decreased stress scores (ES=0.5). However, the athlete possibly exhibited a small decrease in muscle CSA (precision=64.8%;ES=0.4) the week of competition that corresponded with very large changes in body mass (precision=99%;ES=2.8). CONCLUSIONS: The training program was effective in ensuring the athlete was peaked the day of competition based on jumping performance and recovery-stress scores despite small decreases in CSA. Thus, weightlifting coaches and sport scientists working with high-level athletes should monitor jumping performance and recovery-stress state to ensure athletes peak at an appropriate time. PRACTICAL APPLICATIONS: SRSS and SJ testing can be used as monitoring tools for high-level weightlifters preparing for important competitions.

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Abstract available in the Medicine & Science in Sports & Exercise.

PURPOSE: To determine the relative contribution of vastus lateralis (VL) and lateral gastrocnemius (LG) cross-sectional area (CSA) to countermovement jump height (JH) in collegiate athletes. METHODS: Sixty-nine male (n=33, 20.43 ± 1.68 y, 180.34 ± 11.39 cm, 77.54 ± 14.45 kg) and female (n=36, 19.79 ± 1.09 y, 168.46 ± 10.07 cm, 67.33 ± 9.48 kg) collegiate athletes competing in basketball, tennis, cross-country, weightlifting, and volleyball were recruited for the study. Testing was conducted as part of an on-going athlete monitoring program. Athletes were tested on measures of VL and LG CSA using β-mode ultrasonography, and JH measured on force platforms sampling at 1000Hz. Jump height was regressed on age, sex, body mass, VL and LG CSA using a simultaneous multiple linear regression after testing regression assumptions. A relative importance analysis was conducted to determine the relative contribution of each independent variable. The alpha level for all analyses was set at p≤0.05. RESULTS: The model explained 48% of the variance in JH (p<0.001, observed statistical power=0.99). Body mass (B=-0.16, p=0.01), sex (B=-5.10, p<0.001), and VL CSA (B=0.66, p<0.001) were statistical predictors of JH. Age, LG CSA, body mass, sex, and VL CSA contributed 3%, 3%, 7%, 32%, and 55% of the total variance explained by the model, respectively. CONCLUSIONS: Vastus lateralis CSA has a greater contribution to JH than LG CSA while controlling for the variance of age, sex, and body mass. Therefore, greater emphasis should be placed on developing VL CSA than LG CSA for athletes whose goal is to improve JH. Athletes who lose body mass without losing VL CSA may also improve JH.

PURPOSE: To examine changes in muscle architecture, reactive strength, and explosive ability in collegiate volleyball players throughout a competitive season. METHODS: Ten female volleyball players (20.4 ± 1.1 y, 178.3 ± 4.8 cm, 72.6 ± 5.3 kg) were recruited for the study. Athletes were tested at pre-season (T1), pre-taper (T2), and post-taper (T3) on measures of vastus lateralis muscle thickness (MT), pennation angle (PA), and fascicle length (FL) using ultrasonography, countermovement jump reactive strength index modified (RSImod), and peak power allometrically scaled (PPa). Training load (TL: session RPEduration) and strength training volume-load times displacement (VLd) were monitored for 15 wks. One-way repeated measures ANOVAs were used for analysis with alpha level set at p≤0.05. RESULTS: There was a reduction in VLd/wk (p<0.001, d=3.1) and TL/wk (p<0.001, d=2.7) between in-season (T1-T2) and tapering (T2-T3) training phases. There were time effects for MT (p<0.001) and PA (p=0.03). Post-hoc pairwise comparisons revealed changes in MT (increase T1-T2: p<0.001, d=2.8 and T1-T3: p<0.001, d=1.7; decrease T2-T3: p=0.01, d=0.6), PA (increase T1-T2: p=0.02, d=3.9), and no changes in FL or PPa. Despite no time effect, RSImod showed an increasing trend from T2-T3: p=0.04, d=0.23. CONCLUSIONS: In-season training resulted in favorable changes in muscle architecture, which remained elevated above pre-season values following the taper. These changes coupled with the reductions in TL and VLd during the taper may be related to changes in stretch-shortening cycle function during a sport-specific task as inferred from the changes in RSImod

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