This study assessed the effect of resistive training (RT), with or without high-dose chromium picolinate (Cr-pic) supplementation, on body composition and skeletal muscle size of older women. Seventeen sedentary women, age range 54-71 years. BMI 28.8±2.4 kg/m2. were randomly assigned (double-blind) to groups (Cr-pic. n = 9; Placebo, n = 8) that consumed either 924 μg Cr/d as Cr-pic or a low-Cr placebo (<0.2 μg Cr/d) during a 12-week RT program (2 day/ week, 3 sets · exercise−1 · d1,80% of 1 repetition maximum). Urinary chromium excretion was 60-fold higher in the Cr-pic group, compared to the Placebo group (p < .001), during the intervention. Resistive training increased maximal strength of the muscle groups trained by 8 to 34% (p < .001), and these responses were not influenced by Cr-pic supplementation. Percent body fat and fat-free mass were unchanged with RT in these weight-stable women, independent of Cr-pic supplementation. Type I and type II muscle fiber areas of the m. vastus lateralis were not changed over time and were not influenced by Cr-pic supplementation. These data demonstrate that high-dose Cr-pic supplementation did not increase maximal strength above that of resistive training alone in older women. Further, these data show that, under these experimental conditions, whole body composition and skeletal muscle size were not significantly changed due to resistive training and were not influenced by supplemental chromium picolinate.
Wayne W. Campbell, Lyndon J.O. Joseph, Richard A. Anderson, Stephanie L. Davey, Jeremy Hinton and William J. Evans
Kaelin C. Young, Kristina L. Kendall, Kaitlyn M. Patterson, Priyanka D. Pandya, Ciaran M. Fairman and Samuel W. Smith
To assess changes in body composition, lumbar-spine bone mineral density (BMD), and rowing performance in collegelevel rowers over a competition season.
Eleven Division I college rowers (mean ± SD 21.4 ± 3.7 y) completed 6 testing sessions throughout the course of their competition season. Testing included measurements of fat mass, bone-free lean mass (BFLM), body fat (%BF), lumbar-spine BMD, and 2000-m time-trial performance. After preseason testing, rowers participated in a periodized training program, with the addition of resistance training to the traditional aerobic-training program.
Significant (P < .05) improvements in %BF, total mass, and BFLM were observed at midseason and postseason compared with preseason. Neither lumbar-spine BMD nor BMC significantly changed over the competitive season (P > .05). Finally, rowing performance (as measured by 2000-m time and average watts achieved) significantly improved at midseason and postseason compared with preseason.
Our results highlight the efficacy of a seasonal concurrent training program serving to improve body composition and rowing performance, as measured by 2000-m times and average watts, among college-level rowers. Our findings offer practical applications for coaches and athletes looking to design a concurrent strength and aerobic training program to improve rowing performance across a season.
Claudia Ridel Juzwiak, Olga Maria Silverio Amancio, Maria Sylvia Souza Vitalle, Vera Lúcia Szejnfeld and Marcelo Medeiros Pinheiro
In this prospective, cross-sectional study male adolescent tennis players (44) and nonathletic controls (32) were evaluated to determine the effects of physical activity, dietary nutrient intakes, sexual maturation, and body composition on bone-mineral density (BMD). Dietary nutrient intakes and physical activity expenditure were estimated by 4-d diaries. Total body composition, bone-mineral content (BMC), and BMD (L1–L4, femur, and nondominant forearm) were assessed by dual-energy X-ray absorptiometry. Tennis players had significantly greater lean body mass (mean [SEM] 50.6 [1.6] kg vs. 45.1 [1.7] kg, p = .022), trochanter BMD (1.0 [0.02] g/cm2 vs. 0.9 [0.03] g/cm2, p = .032), and dominant forearm BMC (173.7 [7.4] g vs. 146.5 [9.3] g) but lower BMD in the nondominant forearm (0.7 [0.02] g/cm2 vs. 0.8 [0.03] g/cm2, p = .028). Daily average calcium intake was below the recommendation in both groups. No correlation was found between BMD and calcium intake and exercise. Lean body mass was the best predictor of BMD and BMC for both tennis players and controls (R 2 = .825, .628, and .693 for L1–L4, total femur, and nondominant forearm, respectively). Based on these results the authors conclude that lean body mass is the best predictor of BMD and BMC for both tennis players and others. Tennis exerts a site-specific effect, and training should focus on ways minimize this effect. Although calcium intake showed no effect on BMD, nutrition education for young athletes should focus on promoting a balanced diet, providing energy and nutrients in adequate amounts.
Michelle Walsh, Laura Cartwright, Clare Corish, Sheila Sugrue and Ruth Wood-Martin
This study examined the body composition, nutritional knowledge, behaviors, attitudes, and educational needs of senior schoolboy rugby players in Ireland.
Participants included 203 male rugby players age 15–18 yr competing at Senior School’s Cup level in Leinster, Ireland. Estimation of body composition included measurement of height, weight, and percentage body fat (PBF; using bioelectrical impedance analysis, Tanita BC-418). Nutritional knowledge, behaviors, attitudes, and education needs were assessed by questionnaire.
The range of PBF was 5.1–25.3%. Sixty-eight percent of the players in this study had a healthy PBF (10–20%), 32 (22%) were classified as underweight (<10% body fat), and 9.7% (n = 14) were overweight. Assessment of nutritional knowledge demonstrated poor knowledge of the foods required for refueling, appropriate use of sports drinks, and the role of protein in muscle formation. Alcohol consumption and dietary supplement use were reported by 87.7% and 64.5%, respectively. A perception that greater body size enhances sport performance did not predict dietary supplement use. Nutritional advice had been previously sought by 121 players from coaches (66.9%), magazines (42.1%), Web sites (38.8%), peers (35.5%), family (28.1%), sport organizations (16.5%), and health professionals (8.2%). Nutritional knowledge was no better in these players, nor did better nutritional knowledge correlate with positive dietary behaviors or attitudes.
Most players had a healthy PBF. Despite a positive attitude toward nutrition, poor nutritional knowledge and dietary practices were observed in many players. Young athletes’ nutritional knowledge and dietary practices may benefit from appropriate nutritional education.
Ina Garthe, Truls Raastad, Per Egil Refsnes, Anu Koivisto and Jorunn Sundgot-Borgen
When weight loss (WL) is necessary, athletes are advised to accomplish it gradually, at a rate of 0.5–1 kg/wk. However, it is possible that losing 0.5 kg/wk is better than 1 kg/wk in terms of preserving lean body mass (LBM) and performance. The aim of this study was to compare changes in body composition, strength, and power during a weekly body-weight (BW) loss of 0.7% slow reduction (SR) vs. 1.4% fast reduction (FR). We hypothesized that the faster WL regimen would result in more detrimental effects on both LBM and strength-related performance. Twenty-four athletes were randomized to SR (n = 13, 24 ± 3 yr, 71.9 ± 12.7 kg) or FR (n = 11, 22 ± 5 yr, 74.8 ± 11.7 kg). They followed energy-restricted diets promoting the predetermined weekly WL. All athletes included 4 resistance-training sessions/wk in their usual training regimen. The mean times spent in intervention for SR and FR were 8.5 ± 2.2 and 5.3 ± 0.9 wk, respectively (p < .001). BW, body composition (DEXA), 1-repetition-maximum (1RM) tests, 40-m sprint, and countermovement jump were measured before and after intervention. Energy intake was reduced by 19% ± 2% and 30% ± 4% in SR and FR, respectively (p = .003). BW and fat mass decreased in both SR and FR by 5.6% ± 0.8% and 5.5% ± 0.7% (0.7% ± 0.8% vs. 1.0% ± 0.4%/wk) and 31% ± 3% and 21 ± 4%, respectively. LBM increased in SR by 2.1% ± 0.4% (p < .001), whereas it was unchanged in FR (–0.2% ± 0.7%), with significant differences between groups (p < .01). In conclusion, data from this study suggest that athletes who want to gain LBM and increase 1RM strength during a WL period combined with strength training should aim for a weekly BW loss of 0.7%.
Alisa Nana, Gary J. Slater, Will G. Hopkins and Louise M. Burke
Dual-energy X-ray absorptiometry (DXA) is becoming a popular tool to measure body composition, owing to its ease of operation and comprehensive analysis. However, some people, especially athletes, are taller and/or broader than the active scanning area of the DXA bed and must be scanned in sections. The aim of this study was to investigate the reliability of DXA measures of whole-body composition summed from 2 or 3 partial scans. Physically active young adults (15 women, 15 men) underwent 1 whole-body and 4 partial DXA scans in a single testing session under standardized conditions. The partial scanning areas were head, whole body from the bottom of the chin down, and right and left sides of the body. Body-composition estimates from whole body were compared with estimates from summed partial scans to simulate different techniques to accommodate tall and/or broad subjects relative to the whole-body scan. Magnitudes of differences in the estimates were assessed by standardization. In simulating tall subjects, summation of partial scans that included the head scan overestimated whole-body composition by ~3 kg of lean mass and ~1 kg of fat mass, with substantial technical error of measurement. In simulating broad subjects, summation of right and left body scans produced no substantial differences in body composition than those of the whole-body scan. Summing partial DXA scans provides accurate body-composition estimates for broad subjects, but other strategies are needed to accommodate tall subjects.
Timothy G. Lohman, Melanie Hingle and Scott B. Going
Aaron P. Crombie, Pei-Yang Liu, Michael J. Ormsbee and Jasminka Z. Ilich
To examine relationships between changes in body weight, body composition, and fitness level in male students of the general population and those in the Army Reserve Officer Training Corps (ROTC) program during the freshman year of college.
Thirty-seven (18.4 ± 0.7 yr) healthy, nonsmoking, first-semesterresident male students were divided into 3 groups: low active (LA), high active (HA), and ROTC. Baseline (beginning of freshman year) and 6-month follow-up measurements included anthropometry, body composition (by DXA), 3-day food records, and physical activity (PA) assessment.
Weight and body-mass index did not change significantly within or among groups. HA participants compared with LA and ROTC had a significant decrease in body fat (–1.6% ± 2.5% vs. 1.9% ± 1.2% and 0.8% ± 2.2%, respectively). They also had a significant increase in lean mass compared with LA and ROTC (1.8 ± 1.1 kg vs. –0.2 ± 2.0 kg and 0.2 ± 1.7 kg, respectively). All p values were <.05. ROTC and LA participants were similar in all measures of body composition and PA and had significantly lower PA levels than the HA group. No significant relationships were observed between dietary variables and body-composition changes.
These results suggest that higher PA was the most powerful determinant in achieving favorable body-composition outcomes. In addition, current physical training conducted by ROTC at Florida State University (which seems to be a practice nationwide) might not be sufficient to offset gains in body fat.
Michael H. Stone, Kimberly Sanborn, Lucille L. Smith, Harold S. O'Bryant, Tommy Hoke, Alan C. Utter, Robert L. Johnson, Rhonda Boros, Joseph Hruby, Kyle C. Pierce, Margaret E. Stone and Brindley Garner
The purpose of this investigation was to study the efficacy of two dietary supplements on measures of body mass, body composition, and performance in 42 American football players. Group CM (n = 9) received creatine monohy-drate, Group P (n = 11) received calcium pyruvate. Group COM (n = 11) received a combination of calcium pyruvate (60%) and creatine (40%), and Group PL received a placebo. Tests were performed before (Tl) and after (T2) the 5-week supplementation period, during which the subjects continued their normal training schedules. Compared to P and PL. CM and COM showed significantly greater increases for body mass, lean body mass, 1 repetition maximum (RM) bench press, combined 1 RM squat and bench press, and static vertical jump (SVJ) power output. Peak rate of force development for SVJ was significantly greater for CM compared to P and PL. Creatine and the combination supplement enhanced training adaptations associated with body mass/composition, maximum strength, and SVJ; however, pyruvate supplementation alone was ineffective.
Sidnei Jorge Fonseca-Junior, Aldair J. Oliveira, Luiz Lannes Loureiro and Anna Paola Trindade Pierucci
Body composition of adolescent athletes is often evaluated scientifically and in sports by using reference equations developed from nonathlete adolescent populations. The aim of this study was to analyze the validity of predictive equations based on skinfold measurements, as compared with dual-energy X-ray absorptiometry (DXA), to estimate body fat in adolescent modern pentathlon athletes.
51 athletes, 27 male (mean age = 15.1 years; standard deviation, SD = 1.5 years) and 24 female (mean age = 14.2 years; SD = 2.5 years), were assessed using DXA, anthropometric parameters, sports practice anamnesis, and pubertal stages. Agreement between methods was tested with boxplots of mean comparisons using Student’s t test (p < .05), and Bland-Altman plots.
The body density equations of Durnin & Rahaman (1967) and Durnin & Womersley (1974) showed better agreement with DXA than the other predictive equations, for both females (difference between means=-2.03; 2SD = 8.44) and males (difference between means = 0.98; 2SD = 7.30). There were no mean differences between these equations and the reference method (DXA; p > .05), but they did display high variability (2SD).
The high variability among results indicated imprecision. Predictive skinfold equations developed for nonathlete adolescents do not offer good validity for modern adolescent pentathlon athletes, and should be avoided.