Different dietary proteins affect whole body protein anabolism and accretion and therefore, have the potential to influence results obtained from resistance training. This study examined the effects of supplementation with two proteins, hydrolyzed whey isolate (WI) and casein (C), on strength, body composition, and plasma glutamine levels during a 10 wk, supervised resistance training program. In a double-blind protocol, 13 male, recreational bodybuilders supplemented their normal diet with either WI or C (1.5 gm/kg body wt/d) for the duration of the program. Strength was assessed by 1-RM in three exercises (barbell bench press, squat, and cable pull-down). Body composition was assessed by dual energy X-ray absorptiometry. Plasma glutamine levels were determined by the enzymatic method with spectrophotometric detection. All assessments occurred in the week before and the week following 10 wk of training. Plasma glutamine levels did not change in either supplement group following the intervention. The WI group achieved a significantly greater gain (P < 0.01) in lean mass than the C group (5.0 ± 0.3 vs. 0.8 ± 0.4 kg for WI and C, respectively) and a significant (P < 0.05) change in fat mass (−1.5 ± 0.5 kg) compared to the C group (+0.2 ± 0.3 kg). The WI group also achieved significantly greater (P < 0.05) improvements in strength compared to the C group in each assessment of strength. When the strength changes were expressed relative to body weight, the WI group still achieved significantly greater (P < 0.05) improvements in strength compared to the C group.
Paul J. Cribb, Andrew D. Williams, Michael F. Carey and Alan Hayes
Brett S. Nickerson, Michael R. Esco, Phillip A. Bishop, Brian M. Kliszczewicz, Kyung-Shin Park and Henry N. Williford
The purpose of this study was twofold: 1) compare body volume (BV) estimated from dual energy X-ray absorptiometry (DXA) to BV from a criterion underwater weighing (UWW) with simultaneous residual lung volume (RLV), and 2) compare four-compartment (4C) model body fat percentage (BF%) values when deriving BV via DXA (4CDXA) and UWW (4CUWW) in physically active men and women. One hundred twenty-two adults (62 men and 60 women) who self-reported physical activity levels of at least 1,000 MET·min·wk-1 volunteered to participate (age = 22 ± 5 years). DXA BV was determined with the recent equation from Smith-Ryan et al. while criterion BV was determined from UWW with simultaneous RLV. The mean BV values for DXA were not significant compared with UWW in women (p = .80; constant error [CE] = 0.0L), but were significantly higher in the entire sample and men (both p < .05; CE = 0.3 and 0.7L, respectively). The mean BF% values for 4CDXA were not significant for women (p = .56; CE = –0.3%), but were significantly higher in the entire sample and men (both p < .05; CE = 0.9 and 2.0%, respectively). The standard error of estimate (SEE) ranged from 0.6–1.2L and 3.9–4.2% for BV and BF%, respectively, while the 95% limits of agreement (LOA) ranged from ±1.8–2.5L for BV and ±7.9–8.2% for BF%. 4CDXA can be used for determining group mean BF% in physically active men and women. However, due to the SEEs and 95% LOAs, the current study recommends using UWW with simultaneous RLV for BV in a criterion 4C model when high individual accuracy is desired.
Johann C. Bilsborough, Kate Greenway, Steuart Livingston, Justin Cordy and Aaron J. Coutts
The purpose of this study was to examine the seasonal changes in body composition, nutrition, and upper-body (UB) strength in professional Australian Football (AF) players. The prospective longitudinal study examined changes in anthropometry (body mass, fat-free soft-tissue mass [FFSTM], and fat mass) via dual-energy X-ray absorptiometry 5 times during an AF season (start preseason, midpreseason, start season, midseason, end season) in 45 professional AF players. Dietary intakes and strength (bench press and bench pull) were also assessed at these time points. Players were categorized as experienced (>4 y experience, n = 23) or inexperienced (<4 y experience, n = 22). Fat mass decreased during the preseason but was stable through the in-season for both groups. %FFSTM was increased during the preseason and remained constant thereafter. UB strength increased during the preseason and was maintained during the in-season. Changes in UB FFSTM were related to changes in UB-strength performance (r = .37−.40). Total energy and carbohydrate intakes were similar between the experienced and inexperienced players during the season, but there was a greater ratio of dietary fat intake at the start-preseason point and an increased alcohol, reduced protein, and increased total energy intake at the end of the season. The inexperienced players consumed more fat at the start of season and less total protein during the season than the experienced players. Coaches should also be aware that it can take >1 y to develop the appropriate levels of FFSTM in young players and take a long-term view when developing the physical and performance abilities of inexperienced players.
ZáNean McClain and E. Andrew Pitchford
moderate-to-vigorous physical activity (MVPA) is small and nonsignificant. The measurement of body composition may influence the ability to detect this relationship. This study examined associations between adiposity (via dual-energy X-ray absorptiometry) and MVPA (via accelerometer) in 22 adolescents with
Mina Dimov, Jane Khoury and Reginald Tsang
Pregnancy may stress calcium economy in women through fetal calcium requirements, and increasing maternal body weight. Bone is stimulated by compression forces. Playing tennis may decrease bone resorption through intermittent mechanical loading. This study tests the thesis that maternal bone mineral changes during pregnancy in women who play tennis are less compromised compared with nontennis playing controls.
This is a prospective cohort study, a pilot study of 18 healthy pregnant women: 8 tennis players and 10 controls, ages 18 to 39 years. Calcanei bone mineral density (BMD) and ultrasound (Stiffness Index (SI)) measurements, were made at 12 weeks gestation and 2 to 4 weeks postpartum. SI was also measured at 20 to 24, and 33 to 36 weeks gestation. Statistical analysis included analysis of variance and covariance.
Age, height, and weight at study entry were not different between tennis players and controls. At 12 weeks, BMD was higher in tennis players versus controls 0.57 ± 0.02, 0.43 ± 0.03 g/cm2, (P = .003); but not postpartum. SI Z-scores fell significantly during pregnancy in both groups, but were consistently higher in tennis players.
Bone measures dropped overall during pregnancy, but were significantly higher in tennis players versus controls at 12 weeks and through gestation.
Alisa Nana, Gary J. Slater, Will G. Hopkins, Shona L. Halson, David T. Martin, Nicholas P. West and Louise M. Burke
The implications of undertaking DXA scans using best practice protocols (subjects fasted and rested) or a less precise but more practical protocol in assessing chronic changes in body composition following training and a specialized recovery technique were investigated.
Twenty-one male cyclists completed an overload training program, in which they were randomized to four sessions per week of either cold water immersion therapy or control groups. Whole-body DXA scans were undertaken with best practice protocol (Best) or random activity protocol (Random) at baseline, after 3 weeks of overload training, and after a 2-week taper. Magnitudes of changes in total, lean and fat mass from baseline-overload, overload-taper and baseline-taper were assessed by standardization (Δmean/SD).
The standard deviations of change scores for total and fat-free soft tissue mass (FFST) from Random scans (2–3%) were approximately double those observed in the Best (1–2%), owing to extra random errors associated with Random scans at baseline. There was little difference in change scores for fat mass. The effect of cold water immersion therapy on baseline-taper changes in FFST was possibly harmful (-0.7%; 90% confidence limits ±1.2%) with Best scans but unclear with Random scans (0.9%; ±2.0%). Both protocols gave similar possibly harmful effects of cold water immersion therapy on changes in fat mass (6.9%; ±13.5% and 5.5%; ±14.3%, respectively).
An interesting effect of cold water immersion therapy on training-induced changes in body composition might have been missed with a less precise scanning protocol. DXA scans should be undertaken with Best.
Nathan F. Meier, Yang Bai, Chong Wang and Duck-chul Lee
Body composition is a significant health indicator. A wide range of devices and methods are available for its measurement, such as underwater weighing, skinfold testing, body mass index, dual-energy X-ray absorptiometry (DXA), and bioelectrical impedance analysis (BIA). Changes in body composition
Brock Laschowski, Naser Mehrabi and John McPhee
a height of 0.19 m. 9 Table 1 Body segment parameters of the Paralympic wheelchair curler as experimentally measured using dual-energy x-ray absorptiometry 8 Parameter Head and Neck Torso Upper Arm Forearm Hand Length (m) 0.265 ± 0.005 0.588 ± 0.008 0.291 ± 0.005 0.276 ± 0.002 0.123 ± 0.002 Mass (kg
Job Fransen, Stephen Bush, Stephen Woodcock, Andrew Novak, Dieter Deprez, Adam D.G. Baxter-Jones, Roel Vaeyens and Matthieu Lenoir
considerable exposure to radiation or may be considered invasive in some cultures. Therefore, more recently dual-energy X-ray absorptiometry has been used as an alternative to the X-ray method ( 25 ) as it only exposes participants to one-tenth of the radiation dose ( 9 ) or about 0.001 mSv, with the average
Bryan Holtzman, Adam S. Tenforde, Allyson L. Parziale and Kathryn E. Ackerman
’s Institutional Review Board. Informed consent was obtained from participants ≥18 years old and parents of participants <18 years old; participants <18 years old provided informed assent. Retrospective chart review assessed BMD and body fat (measured by dual-energy x-ray absorptiometry [DXA]), laboratory