Reliability and Validity of the 30-15 Intermittent Field Test With and Without a Soccer Ball.

Objective: The purpose of this study was to examine the reliability and validity of the 30-15 Intermittent Field Test (30-15IFT) with and without a ball. Methods: Twenty-four collegiate female soccer players (19.46 ± 1.22 years; 167.01 ± 7.23 cm; 60.95 ± 7.84 kg) performed 1 trial of the Yo-Yo Intermittent Recovery (YYIR) test, 3 trials of the 30-15IFT, and 3 trials of the 30-15IFT with a ball (30-15IFT-B), separated by a minimum 48 hours. Maximal intermittent running velocity (VIFT), heart rate at exhaustion (HRpeak), and rating of perceived exertion (RPE) were collected. Results: Intraclass correlation coefficients (ICCs) between trials demonstrated good reliability during the 30-15IFT in VIFT (ICC = 0.88) and HRpeak (ICC = 0.89), in addition to the 30-15IFT-B VIFT (ICC = 0.83) and HRpeak (ICC = 0.87). VIFT was significantly reduced in 30-15IFT-B (15.82 km h-1) compared to 30-15IFT (17.52 km h-1; p < .001), regardless of trial. HR and RPE were significantly greater in 30-15IFT compared to 30-15IFT-B (p < .05). Estimated maximal oxygen consumption (VO2max) YYIR and estimated VO2max of 30-15IFT and 30-15IFT-B was very strongly (r = 0.82) and strongly (r = 0.68) correlated. Conclusion: The 30-15IFT is considered valid and reliable and the 30-15IFT-B was reliable in female soccer players.

Observation of Women Soccer Players' Physiology During a Single Season.

Paulsen, KM, Butts, CL, and McDermott, BP. Observation of women soccer players' physiology during a single season. J Strength Cond Res 32(6): 1702-1707, 2018-The purpose of this study was to observe heart rate (HR) responses in match settings over the course of a conference season in National Collegiate Athletic Association Division I women's soccer. Twenty-one female collegiate soccer players were provided a HR monitor and instructed to wear it for the duration of match play. Player positions included 6 defenders (DEF), 6 midfielders (MID), and 9 forwards (FWD). Defenders were further identified as either center defenders (CD) or outside defenders (OD). A 1-way analysis of variance was used to determine if mean HR varied between FWD, MID, and DEF. An independent t-test was used to determine if there was a difference between CD and OD HRs. The FWD, MID, and DEF did have significantly different mean HR (p ≤ 0.05), but post-hoc analysis revealed no significant differences (p ≥ 0.05). However, CD demonstrated significantly lower HRs than OD (p = 0.009). Player position, specifically in the CD and OD role, impact the intensity of exercise in match settings and may be used to specify training and conditioning sessions.

Effectiveness of Ice-Sheet Cooling Following Exertional Hyperthermia.

BACKGROUND: The procedure of wrapping a heat casualty in ice-water soaked bed sheets to reduce core temperature has received little investigation, despite the practice and recommendation for its use in some military settings. Thus, the purpose of this study was to investigate the cooling efficacy of ice-sheet cooling (ISC) following exertional hyperthermia. METHODS: 13 (11 males, 2 females) participants (age = 23 ± 3 years, height = 176.5 ± 10.3 cm, mass = 78.6 ± 15.3 kg, body fat = 19.6 ± 8.6%, and body surface area = 1.95 ± 0.22 m2) volunteered to complete 2 randomized, crossover design trials on an outdoor recreation field (34.4 ± 1.4°C, 54.4 ± 4.1% relative humidity). Each trial consisted of exercise (self-paced 400-m warm-up, 1,609-m run, and 100-m sprints) followed by 15 minutes of either lying supine in the shade with no treatment (control [CON]) or being treated with ice-water soaked sheets wrapped around their body (ISC). Physiological (rectal temperature [Tre], heart rate, mean-weighted skin temperature) and perceptual measures (thermal sensation, rating of perceived exertion) were assessed after each exercise protocol, every 3 minutes during treatment, and every 5 minutes during recovery. FINDINGS: By design, there were no differences during exercise between ISC and CON for Tre (p = 0.16), skin temperature (p = 0.52), heart rate (p = 0.62), thermal sensation (p = 0.89), or rating of perceived exertion (p = 0.99). There were greater decreases in Tre at 3 (ISC 0.33 ± 0.26°C vs. CON 0.03 ± 0.30°C, p = 0.01) and 6 minutes (ISC 0.47 ± 0.27°C vs. CON 0.30 ± 0.19°C, p = 0.05) of treatment; however, the overall rate of cooling was not different between trials (CON 0.05 ± 0.02°C/min vs. ISC 0.06 ± 0.02°C/min, p = 0.72). Skin temperature (Tsk) was significantly reduced from 3 minutes (ISC 34.4 ± 1.7°C vs. CON 36.6 ± 0.5°C, p = 0.007) through 15 minutes (ISC 32.4 ± 1.5 vs. CON 36.1 ± 0.4°C, p < 0.001) of treatment. There was a trend for lower heart rate with ISC (p = 0.051). Thermal sensation was reduced from 3 minutes of treatment (ISC 3.5 ± 0.9 vs. CON 4.5 ± 0.6, p = 0.002) through 15 minutes (ISC 2.8 ± 1.0 vs. CON 3.9 ± 0.4, p = 0.005). DISCUSSION: ISC does not provide effective reduction in Tre following exertional hyperthermia compared to no treatment. However, perceptual benefits may warrant the use of ISC in settings where rapid reductions in core temperature are not a concern (i.e., recovery from exercise). Thus, clinicians should continue to utilize validated techniques (i.e., cold-water immersion) for the treatment of exertional heat illnesses.