Our purpose was to assess muscular adaptations during 6 weeks of resistance training in 36 males randomly assigned to supplementation with whey protein (W; 1.2 g/kg/day), whey protein and creatine monohydrate (WC; 0.1 g/kg/day), or placebo (P; 1.2 g/kg/day maltodextrin). Measures included lean tissue mass by dual energy x-ray absorptiometry, bench press and squat strength (1-repetition maximum), and knee extension/flexion peak torque. Lean tissue mass increased to a greater extent with training in WC compared to the other groups, and in the W compared to the P group (p < .05). Bench press strength increased to a greater extent for WC compared to W and P (p < .05). Knee extension peak torque increased with training for WC and W (p < .05), but not for P. All other measures increased to a similar extent across groups. Continued training without supplementation for an additional 6 weeks resulted in maintenance of strength and lean tissue mass in all groups. Males that supplemented with whey protein while resistance training demonstrated greater improvement in knee extension peak torque and lean tissue mass than males engaged in training alone. Males that supplemented with a combination of whey protein and creatine had greater increases in lean tissue mass and bench press than those who supplemented with only whey protein or placebo. However, not all strength measures were improved with supplementation, since subjects who supplemented with creatine and/or whey protein had similar increases in squat strength and knee flexion peak torque compared to subjects who received placebo.
Darren G. Burke, Philip D. Chilibeck, K. Shawn Davison, Darren C. Candow, Jon Farthing and Truis Smith-Palmer
Whitney R.D. Duff, Philip D. Chilibeck, Julianne J. Rooke, Mojtaba Kaviani, Joel R. Krentz and Deborah M. Haines
Bovine colostrum is the first milk secreted by cows after parturition and has high levels of protein, immunoglobulins, and various growth factors. We determined the effects of 8 weeks of bovine colostrum supplementation versus whey protein during resistance training in older adults. Males (N = 15, 59.1 ± 5.4 y) and females (N = 25, 59.0 ± 6.7 y) randomly received (double-blind) 60g/d of colostrum or whey protein complex (containing 38g protein) while participating in a resistance training program (12 exercises, 3 sets of 8–12 reps, 3 days/week). Strength (bench press and leg press 1-RM), body composition (by dual energy x-ray absorptiometry), muscle thickness of the biceps and quadriceps (by ultrasound), cognitive function (by questionnaire), plasma insulin-like growth factor-1 (IGF-1) and C-reactive protein (CRP, as a marker of inflammation), and urinary N-telopeptides (Ntx, a marker of bone resorption) were determined before and after the intervention. Participants on colostrum increased leg press strength (24 ± 29 kg; p < .01) to a greater extent than participants on whey protein (8 ± 16 kg) and had a greater reduction in Ntx compared with participants on whey protein (–15 ± 40% vs. 10 ± 42%; p < .05). Bench press strength, muscle thickness, lean tissue mass, bone mineral content, and cognitive scores increased over time (p < .05) with no difference between groups. There were no changes in IGF-1 or CRP. Colostrum supplementation during resistance training was beneficial for increasing leg press strength and reducing bone resorption in older adults. Both colostrum and whey protein groups improved upper body strength, muscle thickness, lean tissue mass, and cognitive function.
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.
Theocharis Ispoglou, Roderick F.G.J. King, Remco C.J. Polman and Cathy Zanker
To investigate the effects of daily oral L-leucine ingestion on strength, bone mineral-free lean tissue mass (LTM) and fat mass (FM) of free living humans during a 12-wk resistance-training program.
Twenty-six initially untrained men (n = 13 per group) ingested either 4 g/d of L-leucine (leucine group: age 28.5 ± 8.2 y, body mass index 24.9 ± 4.2 kg/m2) or a corresponding amount of lactose (placebo group: age 28.2 ± 7.3 y, body mass index 24.9 ± 4.2 kg/m2). All participants trained under supervision twice per week following a prescribed resistance training program using eight standard exercise machines. Testing took place at baseline and at the end of the supplementation period. Strength on each exercise was assessed by fve repetition maximum (5-RM), and body composition was assessed by dual energy X-ray absorptiometry (DXA).
The leucine group demonstrated significantly higher gains in total 5-RM strength (sum of 5-RM in eight exercises) and 5-RM strength in five out of the eight exercises (P < .05). The percentage total 5-RM strength gains were 40.8% (± 7.8) and 31.0% (± 4.6) for the leucine and placebo groups respectively. Significant differences did not exist between groups in either total percentage LTM gains or total percentage FM losses (LTM: 2.9% ± 2.5 vs 2.0% ± 2.1, FM: 1.6% ± 15.6 vs 1.1% ± 7.6).
These results suggest that 4 g/d of L-leucine supplementation may be used as a nutritional supplement to enhance strength performance during a 12-week resistance training program of initially untrained male participants.
Joseph M. Kindler, Hannah L. Ross, Emma M. Laing, Christopher M. Modlesky, Norman K. Pollock, Clifton A. Baile and Richard D. Lewis
Assessment of physical activity in clinical bone studies is essential. Two bone-specific physical activity scoring methods, the Bone Loading History Questionnaire (BLHQ) and Bone-Specific Physical Activity Questionnaire (BPAQ), have shown correlations with bone density and geometry, but not architecture. The purpose of this study was to determine relationships between physical activity scoring methods and bone architecture in non-Hispanic white adolescent females (N = 24; 18-19 years of age). Bone loading scores (BLHQ [hip and spine] and past BPAQ) and energy expenditure (7-day physical activity recall) were determined from respective questionnaires. Estimates of trabecular and cortical bone architecture at the nondominant radius and tibia were assessed via magnetic resonance imaging. Total body and regional areal bone mineral density (aBMD), as well as total body fat mass and fat-free soft tissue (FFST) mass were assessed via dual energy X-ray absorptiometry. Pearson’s correlations and partial correlations adjusting for height, total body fat mass, and FFST were performed. Hip BLHQ scores were correlated with midtibia cortical volume (r = .43; p = .03). Adjusted hip and spine BLHQ scores were correlated with all midtibia cortical measures (r = .50-0.58; p < .05) and distal radius apparent trabecular number (r = .46-0.53; p < .05). BPAQ scores were correlated with all midtibia cortical (r = .41-0.51; p < .05) and most aBMD (r = .47-0.53; p < .05) measures. Energy expenditure was inversely associated with femoral neck aBMD only after statistical adjustment (r = .49, p < .05). These data show that greater load-specific physical activity scores, but not energy expenditure, are indicative of greater midtibia cortical bone quality, thus supporting the utility of these instruments in musculoskeletal research.
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
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.
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.
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