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  • Author: Sarah Hurst x
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Jennifer Ostrowski, Angelina Purchio, Maria Beck, JoLynn Leisinger, Mackenzie Tucker and Sarah Hurst

Context: Previous research has found ice bags are more effective at lowering intramuscular temperature than gel packs. Recent studies have evaluated intramuscular temperature cooling decreases with ice bag versus Game Ready and with the PowerPlay system wetted ice bag inserts; however, intramuscular temperature decreases elicited by PowerPlay with the standard frozen gel pack inserts have not been examined. Objective: Evaluate the rate and magnitude of cooling using PowerPlay with frozen gel pack (PP-gel) option, PowerPlay with wetted ice bag (PP-ice) option, and control (no treatment) on skin and intramuscular temperature (2 cm subadipose). Design: Repeated-measures counterbalanced study. Setting: University research laboratory. Patients or Other Participants: Twelve healthy college-aged participants (4 men and 8 women; age = 23.08 (1.93) y, height = 171.66 (9.47) cm, mass = 73.67 (13.46) kg, and subcutaneous thickness = 0.90 (0.35) cm). Intervention(s): PowerPlay (70 mm Hg) with either wetted ice bag or frozen gel pack was applied to posterior aspect of nondominant calf for 30 minutes; control lay prone for 30 minutes. Participants underwent each treatment in counterbalanced order (minimum 4 d, maximum 10 d between). Main Outcome Measure(s): Muscle temperature was measured via 21-gauge catheter thermocouple (IT-21; Physitemp Instruments, Inc). Skin temperature was measured via surface thermocouple (SST-1; Physitemp Instruments, Inc). Results: Significant treatment-by-time interaction for muscle cooling (F 10,80 = 11.262, P = .01, ηp2=.585, observed β = 0.905) was observed. PP-ice cooled faster than both PP-gel and control from minutes 12 to 30 (all Ps < .05); PP-gel cooled faster than control from minutes 18 to 30 (all Ps < .05). Mean decreases from baseline: PP-ice = 4.8°C (2.8°C), PP-gel = 2.3°C (0.8°C), and control = 1.1°C (0.4°C). Significant treatment-by-time interaction for skin cooling (F 10,80 = 23.920, P = .001, ηp2=.857, observed β = 0.998) was observed. PP-ice cooled faster than both PP-gel and control from minutes 6 to 30 (all Ps < .05); PP-gel cooled faster than control from minutes 12 to 30 (all Ps < .05). Mean decreases from baseline: PP-ice = 14.6°C (4.8°C), PP-gel = 4.0°C (0.9°C), and control = 1.0°C (1.0°C). Conclusions: PP-ice produces clinically and statistically greater muscle and skin cooling compared with PP-gel and control.

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Kathryn L. Beck, Sarah Mitchell, Andrew Foskett, Cathryn A Conlon and Pamela R. Von Hurst

Ballet dancing is a multifaceted activity requiring muscular power, strength, endurance, flexibility, and agility; necessitating demanding training schedules. Furthermore dancers may be under aesthetic pressure to maintain a lean physique, and adolescent dancers require extra nutrients for growth and development. This cross-sectional study investigated the nutritional status of 47 female adolescent ballet dancers (13–18 years) living in Auckland, New Zealand. Participants who danced at least 1 hr per day 5 days per week completed a 4-day estimated food record, anthropometric measurements (Dual-energy X-ray Absorptiometry) and hematological analysis (iron and vitamin D). Mean BMI was 19.7 ± 2.4kg/m2 and percentage body fat, 23.5 ± 4.1%. The majority (89.4%) of dancers had a healthy weight (5th-85th percentile) using BMI-for-age growth charts. Food records showed a mean energy intake of 8097.3 ± 2155.6kJ/day (48.9% carbohydrate, 16.9% protein, 33.8% fat, 14.0% saturated fat). Mean carbohydrate and protein intakes were 4.8 ± 1.4 and 1.6 ± 0.5g/kg/day respectively. Over half (54.8%) of dancers consumed less than 5g carbohydrate/kg/day, and 10 (23.8%) less than 1.2 g protein/kg/day. Over 60% consumed less than the estimated average requirement for calcium, folate, magnesium and selenium. Thirteen (28.3%) dancers had suboptimal iron status (serum ferritin (SF) <20μg/L). Of these, four had iron deficiency (SF < 12μg/L, hemoglobin (Hb) ≥ 120g/L) and one iron deficiency anemia (SF < 12μg/L, Hb < 120g/L). Mean serum 25-hydroxy vitamin D was 75.1 ± 18.6nmol/L, 41 (91.1%) had concentrations above 50nmol/L. Female adolescent ballet dancers are at risk for iron deficiency, and possibly inadequate nutrient intakes.