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  • Author: Bradley C. Nindl x
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Anne Z. Beethe, Elizabeth F. Nagle, Mita Lovalekar, Takashi Nagai, Bradley C. Nindl and Christopher Connaboy

Purpose: To examine strength, range of motion, anthropometric, and physiological contributions to novice surface-combat-swimming (sCS) performance and establish differences from freestyle-swimming (FS) performance to further understand the transition of FS to sCS performance. Methods: A total of 13 competitive swimmers (7 male and 6 female; 27.7 [2.3] y; 176.2 [2.6] cm; 75.4 [3.9] kg) completed 8 testing sessions consisting of the following: physiological land-based measurements for maximal anaerobic and aerobic capacity and upper- and lower-extremity strength and range of motion, an sCS anaerobic capacity swim test measuring peak and mean force and fatigue index, 2 aerobic capacity tests measuring maximal aerobic capacity for both FS and sCS, and four 500-m performance swims for time, 1 FS, and 3 sCS. Separate multiple linear-regression analysis was used to analyze predictors of both sCS and FS performance models. Results: FS performance was predicted by the final FS maximal oxygen uptake with an R2 of 42.03% (F1,10 = 7.25; P = .0226), whereas sCS performance was predicted by isometric hip-extension peak strength with an R2 of 41.46% (F1,11 = 7.79; P = .0176). Conclusions: Results demonstrate that different physiological characteristics predict performance, suggesting that an altered strategy is used for novice sCS than FS. It is suggested that this may be due to the added constraints as mandated by mission requirements including boots, weighted gear, and clandestine requirements with hips lowered beneath the surface. Further research should examine the kinematics of the sCS flutter kick to improve performance by developing training strategies specific for the task.

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Kim Beals, Katherine A. Perlsweig, John E. Haubenstriker, Mita Lovalekar, Chris P. Beck, Darcie L. Yount, Matthew E. Darnell, Katelyn Allison and Bradley C. Nindl

Special operation forces participating in mountain warfare/cold weather (MWCW) training have higher energy demands, but adequate fueling is difficult to achieve. The purpose of the study was to determine energy expenditure relative to energy intake and examine fueling patterns during 3 days of MWCW training in Naval Special Warfare Sea, Air, Land (SEAL) Qualification Training (SQT) students. Ten SQT students (age: 23.3 ± 1.8 years, height: 182.3 ± 6.4 cm, and weight: 83.6 ± 4.5 kg) were fitted for heart rate and accelerometer monitors during MWCW training. Total daily energy expenditure was determined using a combination of direct observation and heart rate-VO2 regression. Total daily energy intake was collected using the Automated Self-Administered 24 (ASA24) assessment tool. Total daily energy expenditure for river crossing, alpine skills, and mountain patrol were 3,913 ± 293, 4,207 ± 400, and 5,457 ± 828 kcals, respectively. Reported total daily energy intakes were 2,854 ± 657 (river crossing) and 2,289 ± 680 kcals (mountain patrol), producing 1,044 ± 784 and 3,112 ± 1,420 kcal deficits, respectively. SQT students consumed 258 ± 95 g (3.1 ± 1.3 g·kg−1·day−1) of carbohydrates, 130 ± 55 g (1.6 ± 0.7 g·kg−1·day−1) of protein, and 113 ± 39 g (1.4 ± 0.5 g·kg−1·day−1) of fat. MWCW training evolutions elicited high total daily energy expenditure and inadequate energy intake, especially before and during active training sessions, which may lead to decreased work output, early onset fatigue, and increased risk of injury. Increasing total daily energy intake by providing fuel/fluids, primarily carbohydrates, during the planned breaks and “downtime” of each training evolution and focusing on provision of the balance of calories/macronutrients needed for a more complete and expedited recovery over dinner and evening snacks will help bridge the energy gap.

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Bradley C. Nindl, William J. Kraemer, Lincoln A. Gotshalk, James O. Marx, Jeff S. Volek, Jill A. Bush, Keijo Häkkinen, Robert U. Newton and Steve J. Fleck

Regional fat distribution (RFD) has been associated with metabolic derangements in populations with obesity. For example, upper body fat patterning is associated with higher levels of free testosterone (FT) and lower levels of sex-hormone binding globulin (SHBG). We sought to determine the extent to which this relationship was true in a healthy (i.e., non-obese) female population and whether RFD influenced androgen responses to resistance exercise. This study examined the effects of RFD on total testosterone (TT), FT, and SHBG responses to an acute resistance exercise test (ARET) among 47 women (22 ± 3 years; 165 ± 6 cm; 62 ± 8 kg; 25 ± 5 %BF; 23 ± 3 BMI). RFD was characterized by 3 separate indices: waist-to-hip ratio (WHR), ratio of upper arm fat to mid-thigh fat assessed with magnetic resonance imaging (MRI ratio), and ratio of subscapular to triceps ratio (SB/TRi ratio). Skinfolds were measured for the triceps, chest, subscapular, mid-axillary, suprailaic, abdomen, and thigh regions. The ARET consisted of 6 sets of 10 RM squats separated by 2-min rest periods. Blood was obtained pre- and post- ARET. TT, FT, and SHBG concentrations were determined by radioimmunoassay. Subjects were divided into tertiles from the indices of RFD, and statistical analyses were performed by an ANOVA with repeated measures (RFD and exercise as main effects). Significant (p < .05) increases following the AHRET were observed for TT (~25%), FT (~25%), and SHBG (4%). With multiple regression analysis, anthropometric measures significantly predicted pre- concentrations of FT, post-concentrations of TT, and pre-concentrations of SHBG. The SB/TRi and MRI ratios but not the WHR, were discriminant for hormonal concentrations among the tertiles. In young, healthy women, resistance exercise can induce transient increases in testosterone, and anthropometric markers of adiposity correlate with testosterone concentrations.