Search

Background/objectives The purpose was to determine if skinfolds (SF) and bioelectrical impedance analysis (BIA) could provide accurate estimates of body volume (BV) and total body water (TBW), respectively, for use in a 3-compartment (3-C) model to estimate percent body fat (BF%) when compared to laboratory derived measures. Subjects/methods A sample of sixty-four men (age = 22.9 [plus or minus] 5.4 years) and 59 women (age = 21.6 [plus or minus] 4.3 years) participated in the study. Laboratory 3-C (3C.sub.LAB) model BF% was determined with underwater weighing for body volume (BV) and bioimpedance spectroscopy for total body water (TBW). The 3-C field (3C.sub.FIELD) estimates of BF% included BV from the 7-site SF technique and TBW from hand-to-foot BIA. Results A significant difference in BF% (p < 0.01) was found between the 3C.sub.LAB and 3C.sub.FIELD in the entire sample and within the men, but the effect sizes (ES) were small (0.09 and 0.17, respectively). The difference between means was not significant in the women (ES = 0.05, p = 0.332). Compared to the 3C.sub.LAB, the total error (TE) ranged 2.2-2.4% for 3C.sub.FIELD, 5.7-5.8% for SF, and 4.0-4.6% for BIA. Conclusions The findings suggest that BV and TBW derived from SF and BIA, respectively, can be used in a 3C.sub.FIELD model to increase the accuracy of BF% estimates over SF and BIA alone., Author(s): Michael R. Esco [sup.1] , Brett S. Nickerson [sup.2] , Michael V. Fedewa [sup.1] , Jordan R. Moon [sup.3] , Ronald L. Snarr [sup.1] Author Affiliations: (1) Department of [...]

Energy drink use has grown despite limited research to support efficacy or safety and amid concerns when combined with exercise. The purpose of this study was to assess the effects of 10 weeks of once-daily energy drink consumption or energy drink consumption with exercise on measures of body composition, cardiorespiratory fitness, strength, mood, and safety in previously sedentary males. Thirty-eight males were randomly assigned to energy drink + exercise (EX-A), energy drink (NEX-A), placebo + exercise (EX-B), or placebo (NEX-B). All participants consumed 1 drink per day for 10 weeks; EX-A and EX-B participated in 10 weeks of resistance and endurance exercise. Testing was performed before (PRE) and after (POST) the 10-week intervention. No significant (p > 0.05) changes were observed for body composition, fitness, or strength in NEX-A; however, significantly greater decreases in fat mass and percentage body fat and increases in [VO.sub.2]peak were observed in EX-A versus EX-B. Ventilatory threshold (VT), minute ventilation, [[??]O.sub.2] at VT, and power output at VT improved significantly PRE to POST in EX-A but not in EX-B or nonexercising groups. Clinical markers for hepatic, renal, cardiovascular, and immune function, as determined by PRE and POST blood work revealed no adverse effects in response to the energy drink. Mood was not affected by energy drink use. Absent energy restriction or other dietary controls, chronic ingestion of a once-daily low-calorie energy drink appears ineffective at improving body composition, cardiorespiratory fitness, or strength in sedentary males. However, when combined with exercise, preworkout energy drink consumption may significantly improve some physiological adaptations to combined aerobic and resistance training. KEY WORDS caffeine, thermogenic, body composition, taurine, EGCG, green tea

J Strength Cond Res 24(1): 109-113, 2010--The submaximal electromyographic fatigue threshold test ([EMG.sub.FT]) has been shown to be highly correlated to ventilatory threshold (VT) as determined from maximal graded exercise tests (GXTs). Recently, a prediction equation was developed using the [EMG.sub.FT] value to predict VT. The aim of this study, therefore, was to determine if this new equation could accurately track changes in VT after high-intensity interval training (HILT). Eighteen recreationally trained men (mean [+ or -] SD; age 22.4 [+ or -] 3.2 years) performed a GXT to determine maximal oxygen consumption rate ([Vo.sub.2]peak) and VT using breath-by-breath spirometry. Participants also completed a discontinuous incremental cycle ergometer test to determine their [EMG.sub.FT] value. A total of four 2-minute work bouts were completed to obtain 15-second averages of the electromyographic amplitude. The resulting slopes from each successive work bout were used to calculate [EMG.sub.FT]. The [EMG.sub.FT] value from each participant was used to estimate VT from the recently developed equation. All participants trained 3 days a week for 6 weeks. Training consisted of 5 sets of 2-minute work bouts with 1 minute of rest in between. Repeated-measures analysis of variance indicated no significant difference between actual and predicted VT values after 3 weeks of training. However, there was a significant difference between the actual and predicted VT values after 6 weeks of training. These findings suggest that the EMGFT may be useful when tracking changes in VT after 3 weeks of HIIT in recreationally trained individuals. However, the use of [EMG.sub.FT] to predict VT does not seem to be valid for tracking changes after 6 weeks of HILT. At this time, it is not recommended that [EMG.sub.FT] be used to predict and track changes in VT. KEY WORDS cardiorespiratory fitness, muscle fatigue, interval training, cycling

The critical power test provides 2 measures, critical power (CP) and anaerobic working capacity (AWC). In theory, the CP measurement represents the maximal power output that can be maintained without fatigue, and AWC is an estimate of work capacity associated with muscle energy reserves. High-intensity interval training (HIIT) has been shown to be an effective training method for improving endurance performance, including V[O.sub.2PEAK]. In addition, creatine (Cr) supplementation has been reported to improve AWC without training; however, it has shown no effect on CP. The purpose of this study was to examine the effects of 4 weeks of HIIT with Cr supplementation on CP and AWC. Forty-two recreationally active men volunteered to participate in this study. Participants were randomly assigned to 1 of 3 groups: Cr (n = 16), 10 g Cr + 10 g dextrose; placebo (PL, n = 16), 20 g dextrose; control (CON, n = 10), no treatment. Before and after supplementation, each participant performed a maximal oxygen consumption test (V[O.sub.2PEAK]) on a cycle ergometer to establish peak power output (PPO). Participants then completed a CP test involving 3 exercise bouts with the workloads set as a percentage of their PPO to determine CP and AWC. After a 2-week familiarization period of training and supplementing, PPO, CP, and AWC were remeasured before an additional 4 weeks of HIIT and supplementation were completed. Training consisted of 5 sets of 2-minute exercise bouts with 1 minute rest in between performed on the cycle ergometer, with intensities based on PPO. A significant improvement in CP was observed in the Cr group (6.72% [+ or -] 2.54%), whereas PL showed no significant change (3.87% [+ or -] 2.30%), and CON significantly decreased (6.27% [+ or -] 2.38%). Furthermore, no changes in AWC were observed in any of the groups after treatment. The current findings suggest that Cr supplementation may enhance the effects of intense interval endurance training on endurance performance changes. KEY WORDS ergogenic aids, cycle ergometry, muscle buffering capacity, endurance performance

Anthropometric equations, based on 2-compartment models, have been routinely used to estimate body composition in female college athletes; however, these equations are not without error. In an attempt to decrease the error associated with anthropometric equations, updated equations were developed using multiple-compartment models, although the validity of these equations has not yet been established. The purpose of the current investigation was to determine the validity of the updated anthropometric equations and compare them with previously validated generalized equations for estimating percent fat (%fat) in female athletes. Twenty-nine white female NCAA Division I athletes (20 [+ or -] 1 years) volunteered to have their %fat estimated using anthropometric measurements. Skinfold equations included generalized and updated equations and a height and weight--based equation. %fat values were compared with a criterion 4-compartment model. All equations produced low total error (TE) ([less than or equal to] 3.38%fat) and SEE values ([less than or equal to]2.97%fat) and high r values (r [greater than or equal to] 0.78). The 2 updated skinfold equations produced the highest constant error (CE) values, but the tightest limits of agreement ([less than or equal to] 1.58 [+ or -] 4.86%fat; CE [+ or -] 2SD) compared with the 3 generalized Jackson et al. equations ([less than or equal to] 0.92 [+ or -] 5.34%fat), whereas the limits of agreement for the height and weight--based equation ([+ or -] 6.00 %fat) were the widest. Compared with the updated skinfold equations, the generalized Jackson et al. skinfold equations produced nearly identical TE values. Results suggest that the updated skinfold equations are valid but not superior to the generalized Jackson et al. equations, and the height and weight-based equation of Fornetti et al. is not recommended due to the large individual error in this population. Additionally, more than 3 skinfold sites did not improve %fat values. Therefore, the Jackson et al. sum of 3 skinfold equation is the suggested skinfold equation in the white female NCAA Division I athletes. KEY WORDS multi-compartment model; skinfold, field method, body composition; sports

The purpose of this study was to validate the percentage of body fat (%BF) values estimated from the BOD POD (BP) with those obtained from hydrostatic weighing (HW) in athletic American high school boys. Additionally, the %BF values measured via near-infrared interactance (NIR), bioelectrical impedance (BIA), and skinfold (SF) were compared to HW to determine the validity of these measures. Thirty white boys (mean age [+ or -] SD = 15.8 [+ or -] 1.0 years) who where currently participating in organized sports volunteered to have their %BF estimated. Measurements were obtained from NIR, BP, BIA, and SF in random order and concluded with HW. The findings from the present study indicated that the NIR and BIA instruments produced significant (P < 0.008) constant error (CE) and total error (TE) values that were too large to be of practical value (TE > 4.0%BF). The BP produced a significantly (P < 0.008) higher CE with acceptable TE values compared to HW, but compared to all three SF estimations, the BP TE values were higher. Two of the SF equations were nonsignificant (P > 0.008) and had the lowest TE values compared to HW. These data suggest that the BP can produce acceptable body fat measures for athletic white boys but is not superior to estimates made by the SF equations used in this study. KEY WORDS air d splacement plethysmography, near-infrared interactance youth, biolectrical impedance, skinfold