Body fat of competitive volleyball players: a systematic review with meta-analysis.

BACKGROUND: Reference values of body fat for competitive volleyball players are lacking, making it difficult to interpret measurement results. This review systematically summarized published data on the relative body fat of volleyball players and calculated potential differences between sex, measurement method, and competitive level. METHODS: The protocol followed the Preferred Reported Items for Systematic Reviews and Meta-Analysis guidelines. The literature search was conducted using five electronic databases to retrieve all relevant publications from January 1, 2010, to July 1, 2021. The 63 studies including 2607 players that met the inclusion criteria were analyzed using random-effects models. Data were reported as pooled mean body fat with 95% confidence intervals. RESULTS: Body fat for males and females was 12.8% (11.9-13.8%) and 22.8% (21.9-23.7%), respectively. Body fat was 18.3% (16.3-20.4%) measured via skinfolds, 18.4% (15.6-21.2%) via bioelectrical impedance analysis, 24.2% (20.4-28.0%) via dual-energy x-ray absorptiometry and 21.6% (17.4-25.8%) via densitometry. Regional, national, and international-level players had body fat values of 19.5% (17.8-21.2%), 20.3% (18.6-22.0%), and 17.9% (15.7-20.4%), respectively. When the meta-regression was adjusted for the variables sex, measurement method, and competitive level, a significant difference between sex (p < 0.001), dual-energy x-ray absorptiometry and skinfolds (p = 0.02), and national and international-level players (p = 0.02) was found. However, sensitivity analysis revealed that findings regarding measurement method and competitive level were not robust and should, therefore, be interpreted with caution. CONCLUSIONS: Despite the limitations of published data, this meta-analysis provided pooled values for body fat of male and female volleyball players for different competitive levels and measurement methods.

An ecological investigation of average and peak external load intensities of basketball skills and game-based training drills.

This study quantified average and peak external intensities of various basketball training drills. Thirteen youth male basketball players (age: 15.2 ± 0.3 years) were monitored (BioHarness-3 devices) to obtain average and peak external load per minute (EL · min-1; peak EL · min-1) during team-based training sessions. Researchers coded the training sessions by analysing the drill type (skills, 1vs1, 2vs2, 3vs0, 3vs3, 4vs0, 4vs4, 5vs5, 5vs5-scrimmage), court area per player, player's involvement in the drill (in percentage), playing positions (backcourt; frontcourt) and competition rotation status (starter; rotation; bench). Separate linear mixed models were run to assess the influence of training and individual constraints on average and peak EL · min-1. Drill type influenced average and peak EL · min-1 (p < 0.05), but with different directions of effects. EL · min-1 was higher in skills and 4vs0 drills, while higher peak EL · min-1 values were obtained in 5vs5 and 5vs5-scrimmage. Similarly, EL · min-1 was higher when involvement % increased (p = 0.001), while there was an opposite trend for peak EL · min-1 (lower with higher involvement %). Court area per player influenced peak (p = 0.025) but not average demands. No effects were found for playing position or competition rotation status (all p > 0.05), except for a moderately higher EL · min-1 in starters compared to bench players. The external load intensities of basketball training drills substantially vary depending on the load indicator chosen, the training content, and task and individual constraints. Practitioners should not interchangeably use average and peak external intensity indicators to design training but considering them as separate constructs could help to gain a better understanding of basketball training and competition demands.

Analysis of Dietary Intake and Body Composition of Collegiate Runners / Análisis de la Ingesta Dietética y Composición Corporal de Corredores Universitarios

SUMMARY: The aim of this cross-sectional study was to compare dietary intake to published recommendations and to analyze the potential relationship between body composition and dietary intake in collegiate athletes. Eighteen healthy male middle- and long- distance runners (age 20.11 ± 2.72 y; height, 174.7 ± 6.1 cm; body mass, 64.0 ± 7.7 kg), were recruited from a Mexican university track and field team at the beginning of the general preparation phase for national competitions. Participants completed three 24-hour dietary recalls, which were used to estimate dietary intake. Body composition was measured by Dual-energy X-ray absorptiometry (DXA). Athletes displayed high body fat values. Protein intake was significantly higher than published recommendations. Iron, zinc, sodium, and vitamin C intake were significantly higher than recommended values, while potassium and calcium intake were below established recommendations. No significant correlations between body composition variables (i.e body fat, lean body mass, bone mineral content) and dietary intake (i.e energy, macronutrients and selected vitamins and minerals) could be found. These findings suggest that coaches and practitioners should pay close attention to dietary intake and body composition of endurance athletes starting general preparation for competition. Future studies on changes of dietary intake and body composition during off-season and competitive phase, which also track physical activity, are warranted.

El objetivo de este estudio transversal fue comparar la ingesta dietética con las recomendaciones publicadas y analizar la relación potencial entre la composición corporal y la ingesta dietética en corredores universitarios. Dieciocho atletas masculinos sanos de media y larga distancia (edad 20,11 ± 2,72 años; altura, 174,7 ± 6,1 cm; masa corporal, 64,0 ± 7,7 kg), fueron reclutados de un equipo de atletismo de una universidad mexicana al comienzo de la fase de preparación general de competiciones nacionales. Los participantes completaron tres recordatorios dietéticos de 24 horas, que se utilizaron para estimar la ingesta dietética. La composición corporal se midió mediante absorciometría de rayos X de energía dual (DXA). Los atletas mostraron altos valores de grasa corporal. La ingesta de proteínas fue significativamente mayor que las recomendaciones publicadas. La ingesta de hierro, zinc, sodio y vitamina C fue significativamente superior a los valores recomendados, mientras que la ingesta de potasio y calcio estuvo por debajo de las recomendaciones establecidas. No se encontraron correlaciones significativas entre las variables de composición corporal (es decir, grasa corporal, masa corporal magra, contenido mineral óseo) y la ingesta dietética (es decir, energía, macronutrientes y vitaminas y minerales seleccionados). Estos hallazgos sugieren que los entrenadores y los practicantes deberían prestar mucha atención a la ingesta dietética y la composición corporal de los atletas de resistencia que comienzan la preparación general para la competencia. Se justifican estudios futuros sobre los cambios en la ingesta dietética y la composición corporal durante la fase fuera de temporada y competitiva, como también un seguimiento de la actividad física.

Body Composition of Competitive Bodybuilders: A Systematic Review of Published Data and Recommendations for Future Work.

ABSTRACT: Bauer, P, Majisik, A, Mitter, B, Csapo, R, Tschan, H, Hume, P, Martínez-Rodríguez, A, and Makivic, B. Body composition of competitive bodybuilders: a systematic review of published data and recommendations for future work. J Strength Cond Res 37(3): 726-732, 2023-The purpose of this review was to systematically summarize studies measuring the body composition of competitive bodybuilding athletes to provide recommended values for preparation and during competition. The protocol was preregistered with PROSPERO (CRD42020197921) and followed the guidelines of the Preferred Reported Items for Systematic Reviews and Meta-Analysis. A search of 5 electronic databases (PubMed, Web of Science, SportDiscus, CINAHL, and Scopus) was conducted to retrieve all relevant publications from January 1, 2000, up to June 13, 2021. Of 16 studies meeting the inclusion criteria, 6 presented longitudinal data on competition preparation and were discussed in detail. In the general preparation phase, body fat levels of bodybuilding athletes ranged between 15.3 and 25.2% (female) and from 9.6 to 16.3% (male). Close to competition, however, body fat levels were substantially lower, ranging from 8.1 to 18.3% for female and 5.8-10.7% for male athletes. All studies comparing relative body fat values at various time points during competition preparation found significant reductions between 30 and 60% in relative body fat, whereas lean mass was mostly maintained. Findings from the studies included in this review suggest that most bodybuilding competitors keep resistance training volume high while increasing aerobic training volume when preparing for competition. Findings on energy intake and macronutrient distribution were unclear and should be addressed in future studies. Further research, especially on contest preparation, is warranted and should include more details about training programs, nutritional strategies, psychosocial situation, anabolic androgen steroid, and supplement use as well as measurement protocols and preparation.

Body Fat of Basketball Players: A Systematic Review and Meta-Analysis.

BACKGROUND: This study aimed to provide reference values for body fat (BF) of basketball players considering sex, measurement method, and competitive level. METHODS: A systematic literature research was conducted using five electronic databases (PubMed, Web of Science, SPORTDiscus, CINAHL, Scopus). BF values were extracted, with analyses conducted using random-effects models and data reported as percentages with 95% confidence intervals (CI). RESULTS: After screening, 80 articles representing 4335 basketball players were selected. Pooled mean BF was 13.1% (95% CI 12.4-13.8%) for male players and 20.7% (95% CI 19.9-21.5%) for female players. Pooled mean BF was 21.4% (95% CI 18.4-24.3%) measured by dual-energy X-ray absorptiometry (DXA), 15.2% (95% CI 12.8-17.6%) via bioelectrical impedance analysis (BIA), 12.4% (95% CI 10.6-14.2%) via skinfolds and 20.0% (95% CI 13.4-26.6%) via air displacement plethysmography. Pooled mean BF across competitive levels were 13.5% (95% CI 11.6-15.3%) for international, 15.7% (95% CI 14.2-17.2%) for national and 15.1% (95% CI 13.5-16.7%) for regional-level players. As the meta-regression revealed significant effects of sex, measurement method and competitive level on BF, the meta-analysis was adjusted for these moderators. The final model revealed significant differences in BF between male and female players (p < 0.001). BF measured by DXA was significantly higher than that measured by BIA or skinfolds (p < 0.001). International-level players had significantly lower BF than national and regional-level players (p < 0.05). CONCLUSIONS: Despite the limitations of published data, this meta-analysis provides reference values for BF of basketball players. Sex, measurement method and competitive level influence BF values, and therefore must be taken into account when interpreting results.

Acute Effects of Back Squats on Countermovement Jump Performance Across Multiple Sets of a Contrast Training Protocol in Resistance-Trained Men.

Bauer, P, Sansone, P, Mitter, B, Makivic, B, Seitz, LB, and Tschan, H. Acute effects of back squats on countermovement jump performance across multiple sets of a contrast training protocol in resistance-trained men. J Strength Cond Res 33(4): 995-1000, 2019-This study was designed to evaluate the voluntary postactivation potentiation (PAP) effects of moderate-intensity (MI) or high-intensity (HI) back squat exercises on countermovement jump (CMJ) performance across multiple sets of a contrast training protocol. Sixty resistance-trained male subjects (age, 23.3 ± 3.3 years; body mass, 86.0 ± 13.9 kg; and parallel back squat 1-repetition maximum [1-RM], 155.2 ± 30.0 kg) participated in a randomized, crossover study. After familiarization, the subjects visited the laboratory on 3 separate occasions. They performed a contrast PAP protocol comprising 3 sets of either MI (6 × 60% of 1-RM) or HI back squats (4 × 90% of 1-RM) or 20 seconds of recovery (CTRL) alternated with 7 CMJs that were performed at 15 seconds, and 1, 3, 5, 7, 9 and 11 minutes after the back squats or recovery. Jump height and relative peak power output recorded with a force platform during MI and HI conditions were compared with those recorded during control condition to calculate the voluntary PAP effect. Countermovement jump performance was decreased immediately after the squats but increased across all 3 sets of MI and HI between 3 and 7 minutes after recovery. However, voluntary PAP effects were small or trivial, and no difference between the 3 sets could be found. These findings demonstrate that practitioners can use MI and HI back squats to potentiate CMJs across a contrast training protocol, but a minimum of 3 minutes of recovery after the squats is needed to benefit from voluntary PAP.