Muscle Damage, Soreness, and Stress During Preseason Training in Collegiate Swimmers.

BACKGROUND: In 2014, 6 collegiate swimmers were hospitalized for symptomatic exertional rhabdomyolysis. OBJECTIVE: To serially monitor and assess relationships between skeletal muscle membrane disruption, upper body soreness (UBS) and lower body soreness (LBS), and stress during the first 6 weeks (timepoints) of preseason training in collegiate male and female swimmers. DESIGN: Prospective observational study. SETTING: College/university. PARTICIPANTS: Forty swimmers. INDEPENDENT VARIABLES: Upper and lower body soreness rating (0-10); testosterone (T), cortisol (C), and T/C ratio. MAIN OUTCOME MEASURES: Creatine kinase (CK) and myoglobin (over time) versus independent variables. RESULTS: Weekly training load consisted of ∼87% swimming, ∼5% running, and ∼8% weight training, which increased from 15.8 hours to 20.5 total training hours per week over the first 6 weeks of training. Muscle damage in collegiate swimmers was modest and peaked after the first week of training (week 2) for men (CK = 438 ± 259 U/L; P < 0.0001; r2 = 0.28; myoglobin = 47 ± 18 ng/mL; P = 0.001; r2 = 0.22) and women (CK = 446 ± 723 U/L; P < 0.01; r2 = 0.13; myoglobin = 63 ± 140 ng/mL, not significant) with high variability. Data were presented as peak mean ± SD, significant P value, and r2 from repeated-measures analysis of variance. A temporal disconnect was noted between muscle damage and UBS, which peaked at week 5 in both men (5 ± 2; P < 0.0001; r2 = 0.44) and women (6 ± 2; P < 0.0001; r2 = 0.57). The serum cortisol level decreased over time, which peaked at week 1 (baseline) in men (15 ± 6 µg/dL; P = 0.0004; r2 = 0.38) and women (19 ± 10 µg/dL; P < 0.0001; r2 = 0.49). The testosterone level remained unchanged, which promoted an anabolic hormonal environment that peaked at week 6 (increasing T/C ratio) in men (58 ± 32; P = 0.0003; r2 = 0.31) and women (4 ± 3; P = 0.04; r2 = 0.18) despite gradual increases in training and soreness. CONCLUSIONS: Muscle soreness does not parallel muscle membrane disruption. A 1-week "transition" period is required for muscles to adapt to intense/novel training.

Rate of and factors affecting sonographic visualization of the appendix in asymptomatic children.

Reported sonographic visualization rates of the appendix in children are variable. Visualization rates may be affected by patient's age and various patients' physical characteristics. The purpose of this study is to determine the frequency of sonographic visualization of the appendix by pediatric sonographers, to assess factors that may affect visualization of the appendix, and to define the characteristics of the appendix and periappendiceal region in asymptomatic children. Asymptomatic children between the ages of 2 and 18 were prospectively enrolled and evaluated for 15 min by pediatric sonographers. Of the 123 patients, the entire appendix was seen in 68 patients (55.2 %) and at least partially visualized in an additional 14 for a total of 82 patients (66.7 %). Visualization rate was not affected by body mass index, age, or gender. Appendiceal characteristics and periappendiceal findings were similar to previously published data. The average time required to initially detect the appendix was 275.2 + 211.3 s.

Dehydration is how you define it: comparison of 318 blood and urine athlete spot checks.

Clinical medicine defines dehydration using blood markers that confirm hypertonicity (serum sodium concentration ([Na+])>145 mmol/L) and intracellular dehydration. Sports medicine equates dehydration with a concentrated urine as defined by any urine osmolality (UOsm) ≥700 mOsmol/kgH2O or urine specific gravity (USG) ≥1.020. OBJECTIVE: To compare blood versus urine indices of dehydration in a cohort of athletes undergoing routine screenings. METHODS: 318 collegiate athletes (193 female) provided blood and urine samples and asked to rate how thirsty they were on a 10-point visual analogue scale. Serum was analysed for [Na+], while serum and UOsm were measured using an osmometer. USG was measured using a Chemstrip. Data were categorised into dehydrated versus hydrated groupings based on these UOsm and USG thresholds. RESULTS: Using UOsm ≥700 mOsmol/kgH2O to define dehydration, 55% of athletes were classified as dehydrated. Using any USG ≥1.020 to define dehydration, 27% of these same athletes were classified as dehydrated. No athlete met the clinical definition for dehydration (hypertonicity; serum [Na+]>145 mmol/L). Normonatremia (serum [Na+] between 135 mmol/L and 145 mmol/L) was maintained in 99.7% of athletes despite wide variation in UOsm (110-1298 mOsmol/kgH2O). A significant correlation was confirmed between serum [Na+] versus UOsm (r=0.18; P<0.01), although urine concentration extremes did not reflect derangement in serum markers or thirst rating. CONCLUSION: Urine concentration thresholds classified 27%-55% of collegiate athletes as dehydrated, while no athlete was dehydrated according to blood [Na+] measurement. Practitioners should caution against using urine indices to diagnose or monitor dehydration, because urinary output is a response rather than a reflection of (tightly regulated) blood tonicity.