Associations of Changes in Body Composition and Athletic Performance in Collegiate American Football Players

Football practitioners ubiquitously employ offseason resistance training to improve on-field performance. Early offseason training is frequently designed to emphasize accretion of lean and total body mass. While this is a main objective of sport-specific conditioning, there are few investigations comparing correlated changes in body composition, maximal strength, and football-specific performance tests after an early-offseason training program. PURPOSE: The purpose of this analysis was to quantify the relationship between changes in athletic performance and body composition in collegiate American football players. METHODS: Before and after a 7-week offseason training program, body composition and athletic performance were assessed in NCAA Division III American football players. Body composition was estimated using dual-energy X-ray absorptiometry (DXA; Hologic Horizon). One-repetition maximum (1RM) strength was assessed for the barbell back squat and front squat exercises. Vertical jump height, 40-yard dash time, broad jump distance, and pro agility shuffle time were also assessed. The sample size ranged from 17 to 19, depending on the specific performance test. Using Pearson’s product-moment correlations, the relationships between percent changes in DXA variables and athletic performance outcomes were examined.RESULTS: A trend for a positive correlation between changes in lower body FFM and front squat 1RM (r: 0.43, p: 0.08), but not back squat 1RM (r: -0.03, p: 0.92), was observed. Additionally, a significant positive correlation was observed between pro agility shuffle time and DXA BM (r: 0.50, p: 0.03) and total FFM (r: 0.49, p: 0.04), but not FM (r: 0.06, p: 0.80). In contrast, no correlations between changes in body composition variables and changes in vertical jump height, 40-yard dash time, or broad jump height were observed (range of r: -0.36 to 0.31, p\u3e0.05 for all).CONCLUSION: Increases in FFM may predict improvements in front squat 1RM but impairments in pro agility shuffle performance, with no relationships observed for vertical jump height, 40-yard dash time or back squat. Additional phases of training that specialize in developing maximal power and velocity are likely necessary to maximize athletic development

Offseason Body Composition Changes Detected by Dual-Energy X-Ray Absorptiometry Versus Multifrequency Bioelectrical Impedance Analysis in Collegiate American Football Athletes

In American football, offseason training is designed to promote increases in muscle strength and size in athletes. Tracking changes in body composition may confer key information about the effectiveness of training programs to football practitioners. PURPOSE: The present study assessed the relationship between body composition changes estimated by dual-energy x-ray absorptiometry (DXA) and bioelectrical impedance analysis (BIA) in football players during the initial period of an offseason training program. METHODS: Body composition in 29 NCAA Division III American football players (mean ± SD; age: 19.7 ± 1.5 y; height: 179.8 ± 6.6 cm; body mass [BM]: 96.1 ± 12.6 kg; DXA body fat: 20.9 ± 4.4%) was estimated using BIA (InBody 770) and DXA (Hologic Horizon) before and after a seven-week training intervention. Repeated measures analysis of variance, concordance correlation coefficients, and Bland-Altman analysis alongside linear regression were used to detect differences in cross-sectional estimates and change values, the strength of correlation, and determine the degree of proportional bias between methods, respectively. RESULTS: Significant method by time interactions were observed for BM (p = 0.03), arms fat-free mass (FFM) (p = 0.03), and legs FFM (p = 0.01). Post hoc comparisons indicated that DXA – but not BIA – detected increases in FFM of the arms and legs. Time main effects indicated an increase in total FFM (p = 0.004) and trunk FFM (p = 0.002) from pre to post. Finally, method main effects indicated higher leg FM values for DXA (p \u3c 0.001) and higher trunk FM values for BIA (p \u3c 0.001). No significant effects were observed for total FM (p = 0.92) or arms FM (p = 0.13). Changes in total BM (CCC = 0.96), FFM (CCC = 0.49), and fat mass (CCC = 0.50) were significantly correlated between BIA and DXA. CONCLUSION: DXA and BIA may similarly track increases in whole-body FFM in American collegiate football players; however, BIA may possess less sensitivity to detect segmental FFM increases, particularly in the appendages

Performance and Body Composition Changes Following an Offseason Training Period in DIII Collegiate American Football Athletes

Current literature shows that body composition and increased muscle mass correlate with improved performance for American football players thus assessment of these variables at appropriate times throughout competitive cycle are important for tracking individual adaptions but also in assessing the effectiveness of the prescribed training program. PURPOSE: This study assessed changes in anaerobic performance, total body mass (BM), fat-free mass (FFM), and percent body fat (PBF) in football players following a seven-week offseason mesocycle. METHODS: 29 NCAA Division III football players (mean ± SD; age: 19.7 ± 1.5 y; height: 179.8 ± 6.6 cm; body mass [BM]: 96.1 ± 12.6 kg; DXA body fat: 20.9 ± 4.4%) participated in assessments of performance and body composition body pre- and post- mesocycle. Performance testing was assessed at pre- and post-training timepoints on a subset of athletes that were not restricted (injury, etc.) from maximal testing at these timepoints. This data was from the initial cycle of their offseason training program which included seven weeks of hypertrophy focused training volumes. Performance tests administered included: bench press 1 RM (BP), bench press reps (BPR), incline bench press, back squat 1RM (BS), front squat 1 RM (FS), hang clean 3 RM, 40-yard dash (YD), broad jump, vertical jump (VJ), and pro agility shuttle. BM, FFM, and PBF were estimated via dual x-ray absorptiometry (DXA). RESULTS: Performance improved in all tests except for broad jump and pro agility shuttle. Post-mesocycle performance increases were observed in BP (p \u3c 0.001), BPR (p \u3c0.001), BS (p \u3c0.001), FS (p \u3c 0.001), YD (p \u3c 0.001), and VJ (p \u3c 0.001). Significant training induced changes were observed for: BM increased 1.12kg (p \u3c 0.01962), PBF decreased by 0.686 kg (p \u3c0.004), and FFM increased by 1.57 kg (p \u3c 0.0001). CONCLUSION: This study confirms that a well-structured strength and conditioning program for Division III football players will improve performance in a variety of strength and power related assessments. These changes, though observed over a relatively short amount of time, can translate to competitive performance in conjunction with improved body composition and fat-free mass increases

Relationship Between Changes in Upper Body Fat-Free Mass and Bench Press Performance in American Football Players

Horizontal pushing strength and strength endurance are relevant attributes for blocking and block shedding in American football. Since most positions in American football require the ability to either block or shed a block, and since bench press repetitions to failure (RTF) with 225 pounds is a component of the NFL draft combine, improving horizontal pushing strength and strength endurance have been key areas of emphasis for strength and conditioning coaches working with these athletes. PURPOSE: The purpose of this analysis was to quantify the relationship between changes in upper body fat-free mass (FFM) and metrics of bench press performance in American football players. METHODS: Body composition and muscular performance were assessed in NCAA Division III American football players. Upper body FFM was obtained from dual-energy X-ray absorptiometry (DXA; Hologic Horizon) before and after a seven-week offseason training period. Barbell bench press one-repetition maximum (1RM), incline barbell bench press 1RM, and RTF with 225 pounds on the barbell bench press were also determined before and after the training period. Using Spearman’s rank correlations, the relationships between percent changes in upper body FFM and bench press 1RM (n=19), bench press RTF with 225 pounds (n=15), and incline bench press 1RM (n=18) were evaluated. RESULTS: Relative changes in bench press 1RM and DXA upper body FFM exhibited a weak, non-significant correlation (ρ: 0.38, p: 0.11). However, there was a moderate strength, significant correlation between relative changes in bench press RTF with 225 pounds and DXA upper body FFM (ρ: 0.53, p: 0.04). For relative changes in incline bench press 1RM, there was a weak, non-significant correlation with DXA upper body FFM (ρ: 0.24, p: 0.36). CONCLUSION: Of the performance tests assessed, only changes in bench press RTF with 225 pounds and changes in DXA upper body FFM were positively correlated. Therefore, strength and conditioning coaches working with athletes who plan on entering the NFL draft may want to consider dedicating time to increasing upper body FFM gains prior to the draft as it appears to be positively correlated with performance on this NFL combine test

The Effect of Body Composition Methodology on Resulting Energy Availability Assessments

Energy availability (EA) is defined as the total daily energy available to an individual after accounting for that expended during exercise and standardized to fat-free mass (FFM). Generally, EA values less than 30 kcal/kg FFM/day are considered “low” and have been associated with deleterious effects on reproductive and hormonal health in females. However, it is unclear whether the method used to estimate FFM influences the resulting EA values to a degree that may affect interpretation and clinical decision-making. PURPOSE: To determine the effect of FFM values derived from various methods of body composition assessment on the resulting range and interpretation of EA values. METHODS: Four EA estimates were generated in 38 healthy females (mean ± SD age: 25.6 ± 6.2 years; height: 163.6 ± 7.4 cm; weight: 64.7 ± 13.8 kg) using different combinations within a reasonable range of lower and higher (25 and 35 kcal/kg bodyweight, respectively) energy intake values and lower and higher (3.5 and 7 kcal/kg bodyweight, respectively) exercise energy expenditure values. Resulting estimates were then standardized to FFM values from air displacement plethysmography (ADP), bioelectrical impedance spectroscopy (BIS), and bioelectrical impedance analysis (BIA) from both a research-grade (multi-frequency) and consumer-grade (dual-frequency) device. Resulting EA values were then compared to those using FFM from dual-energy x-ray absorptiometry (DXA). Each estimate was assigned to one of three EA “zones”: “low” (less than 30 kcal/kg FFM), “reduced” (30-44.9 kcal/kg FFM), or “adequate” (≥45 kcal/kg FFM). Individual EA estimates that were in different zones when compared between two devices were considered discordant. RESULTS: When compared to DXA-derived estimates, EA values were discordant in up to 13-16% of individuals depending on body composition method used. Discordant values were generally more common in the plots assuming higher (35 kcal/kg bodyweight) energy intake values and were most likely to be considered “adequate” using DXA-derived FFM versus “reduced” using alternate methods. CONCLUSION: EA estimates are generally robust to the method of body composition assessment used. However, divergent interpretations may occur in a small minority of individuals in which alternate methods may provide lower EA values than DXA

A Between-sex Comparison of the Validity of Body Fat Percentage Estimates From Four Bioelectrical Impedance Analyzers

Bioelectrical impedance analysis (BIA) devices administer electrical currents through surface electrodes in contact with the hands and/or feet. The measured reactance and resistance of various bodily tissues to these currents are then used to estimate body fat percentage (BFP) and other body composition values of interest based on algorithms derived from validation data. Owing to different patterns of fat distribution between sexes, it is unclear whether the configuration of electrodes (i.e., hand-to-hand, foot-to-foot, or hand-to-foot) may affect the validity of these devices in males versus females. PURPOSE: The purpose of this study was to determine the validity of BFP values across four BIA devices – one consumer-grade foot-to-foot device (RENPHO Smart Bathroom Scale), one consumer-grade hand-to-hand device (Omron HBF-306), one consumer-grade octapolar device (InBody H20N), and one research-grade octapolar device (Seca mBCA 515/514) – against a criterion four-compartment model (4C), and to compare these values between males and females. METHODS: Seventy-four healthy participants (35 males and 39 females) were included in this analysis. Participants abstained from all food, fluid, caffeine, and alcohol for at least 8 hours prior to each visit. Total error (TE) was calculated as the root mean square error between the estimate of each BIA device and that of the 4C model. Standard error of the estimate (SEE) was defined as the residual standard error value from ordinary least squares regression. Constant error (CE) was calculated as the average difference between the estimate of each BIA device and that of the 4C model. RESULTS: Participants had a mean ±SD age of 27.2 ±7.3 years, height of 168.1 ±8.9 cm, weight of 72.2 ±16.7 kg, and 4C BFP of 24.9 ±9.2%. In the entire sample, ranges for validity metrics of interest were as follows: TE: 3.2% (Seca) to 7.2% (RENPHO); SEE: 3.3% (Seca) to 5.7% (RENPHO); CE: -0.02 ±3.4% (InBody) to -3.46 ±4.1% (Omron). Across all devices, both TE and SEE were lower in females, with the largest between-sex differences observed for the InBody and RENPHO. Both octapolar devices (InBody and Seca) exhibited low group-level error in males and females (all CE within ±0.32%). Meanwhile, the RENPHO and Omron devices generally underestimated BFP with a greater degree of underestimation in females (CE of -2.6% and -3.7%, respectively) than males (CE of -0.1% and -3.2%, respectively), particularly for the RENPHO. CONCLUSION: Among the four BIA devices investigated, octapolar devices tended to have higher validity overall. All devices demonstrated lower TE and SEE in females, with the greatest between-sex differences observed in the InBody and RENPHO models. Users should be aware that commercially available hand-to-hand or foot-to-foot BIA devices such as the Omron and RENPHO models used in this study may systematically underestimate BFP compared to a criterion 4C model. In contrast, hand-to-foot octapolar analyzers exhibit strong group-level validity in both sexes

Validity of Hand-to-Foot and Foot-to-Foot Consumer Bioimpedance Analyzers: A Four-Compartment Model Comparison

Body fat percentage (BF%) is a useful variable for predicting disease risk and determining overall fitness. Consumer-grade bioimpedance analyzers seek to provide accurate body composition data while remaining affordable and accessible. PURPOSE: The purpose of this study was to compare body fat percentages obtained from hand-to-foot and foot-to-foot consumer bioimpedance analyzers to a gold standard 4-compartment (4C) model. METHODS: Seventy-five adults (40 F, 35 M; age: 27.2 ± 7.3 y; height: 168.1 ± 8.8 cm; BM: 72.1 ± 16.6 kg; 4C model BF%: 25.0 ± 9.2%) were evaluated by a 4C model, a consumer-grade hand-to-foot bioimpedance analyzer (BIA-HF; Tanita BC568) and two consumer-grade foot-to-foot bioimpedance analyzers (BIA-FF; Tanita BC554 and Tanita UM081). The 4C model comprised dual-energy X-ray absorptiometry, air displacement plethysmography, and bioimpedance spectroscopy. BF% estimates obtained by each bioimpedance analyzer were compared to the criterion 4C using the coefficient of determination (R2), standard error of the estimate (SEE), and Bland-Altman analysis. RESULTS: BIA-HF underestimated BF% by 1.4 ± 4.1%, and both BIA-FF overestimated BF% by 0.5 to 0.6 ± 5.7%. The R2 value was higher for BIA-HF as compared to both BIA-FF analyzers (0.81 vs. 0.64). The SEE and 95% limits of agreement (LOA) were lower for BIA-HF (SEE: 4.0%; LOA: 8.1%) as compared to both BIA-FF (SEE: 5.6%; LOA: 11.2%). No method demonstrated proportional bias based on Bland-Altman analysis. CONCLUSION: While both hand-to-foot and foot-to-foot consumer-grade bioimpedance analyzers demonstrated potentially meaningful errors when compared to a gold standard method, the hand-to-foot device exhibited better overall performance. Specifically, a stronger linear agreement with the 4C model and lower individual-level errors were observed with the hand-to-foot model as compared to both foot-to-foot models from the same manufacturer. The superior performance of the hand-to-foot analyzer could be due to its direct testing of both the upper and lower body, which is more similar to the methods used in the 4C model and a better representation of an individual’s overall body composition

Alpha-Cyclodextrin-Containing Beverages for Hydration Enhancement in Humans

A substantial portion of the world’s population may be inadequately hydrated, and dehydration is associated with several disease states and acute impairments in exercise performance. As such, there is continued interest in novel strategies to promote adequate hydration. The carbohydrate alpha-cyclodextrin has recently been shown to enhance water uptake through human aquaporins expressed in a single-cell model and promote longevity in model multicellular organisms. However, there is no relevant human research examining the potential hydrating effects of alpha-cyclodextrin-containing beverages. PURPOSE: To determine if novel beverage formulations containing alpha-cyclodextrin improve a bioimpedance-based hydration marker in humans. METHODS: In a randomized, double-blind, crossover design, eight adults (5 M, 3 F; [mean ± SD] age: 24.9 ± 4.2 years; height: 169.6 ± 5.5 cm; weight: 71.2 ± 13.2 kg; body mass index: 24.6 ± 3.2 kg/m2; body fat: 17.0 ± 5.6%) completed trials including the ingestion of 1 liter of still water (control; CON), still water plus alpha-cyclodextrin (CD), or still water plus alpha- cyclodextrin and complexing agents (B-vitamins and amino acids; Complex). Before beverage ingestion, and every 15 minutes for two hours following beverage ingestion, bioimpedance spectroscopy was performed to estimate phase angle values as a noninvasive marker of cellular hydration. Phase angle was calculated as: arctan(/) × (180°/), where Xc is the reactance (indicative of the capacitive properties of the cell membrane) and R is resistance (opposition to flow of electrical current), both obtained from bioimpedance spectroscopy. Due to the pilot nature of this trial, data were analyzed using descriptive statistics only (data presented as median ± interquartile range). RESULTS: Two hours after completion of beverage ingestion, median ± interquartile range changes in phase in angle were 3.4 ± 1.7% for CON, 4.6 ± 1.2% for CD, and 5.4 ± 3.3% for Complex. Xc changes were 9.9 ± 2.9% for CON, 10.9 ± 3.0% for CD, and 11.1 ± 3.1% for Complex. R changes were 6.5 ± 1.4% for CON, 6.8 ± 1.9% for CD, and 5.6 ± 1.1% for Complex. CONCLUSION: The results of this pilot study indicate the potential for alpha-cyclodextrin- containing beverages to improve a bioimpedance-based hydration marker, phase angle, in humans, with the potential that B-vitamins and amino acids may further enhance hydration beyond alpha-cyclodextrin alone. The larger improvements in phase angle in the Complex group were due to a greater increase in bioelectrical reactance alongside a smaller increase in bioelectrical resistance. Future research with larger sample sizes should examine the potential for these beverages to improve human hydration and health

Comparison of Laboratory-Grade and Consumer-Grade Hand-to-Foot Bioelectrical Impedance Analyzers for Body Composition Estimation

Bioelectrical impedance analysis (BIA) is a simple and effective technique to estimate body composition, including body fat percentage (BFP). While these analyzers are a popular method of describing a person’s body composition, laboratory-grade devices are expensive and inaccessible to most people. As a result, they may be an unrealistic method for consumers to use. However, consumer-grade devices are increasingly available. PURPOSE: The purpose of this study was to compare laboratory-grade and consumer-grade bioelectrical impedance analyzers. METHODS: Seventy-five adults (40 F, 35 M) were evaluated using a laboratory-grade, hand-to-foot, multifrequency bioelectrical impedance analyzer (BIALAB; Seca mBCA 515) and a consumer-grade, hand-to-foot, single frequency bioelectrical impedance analyzer (BIACON; Omron HBF-516). Both devices administer undetectable electrical pulses through one extremity that are measured at another extremity, where the voltage drop (impedance) is determined. This information is used to estimate body fluids and composition. RESULTS: A strong, statistically significant correlation between devices was observed for BFP (r: 0.93, R2: 0.87, pCON overestimated BFP by 3.5 ± 3.4% (mean ± SD) relative to BIALAB (BIACON: 28.3 ± 9.6%; BIALAB: 24.8 ± 9.3%; pCONCLUSION: These results collectively suggest that while the laboratory-grade and consumer-grade analyzers in our study exhibit strong correlations when assessing a group of individuals, the consumer-grade device overestimates BFP. Additionally, the SEE indicates that 3.4% error can be expected with the consumer-grade device. Overall, the Omron HBF-516 consumer-grade device may be an adequate and affordable option to estimate body composition in some contexts, but results should be interpreted cautiously when used in individuals

Day-to-Day Precision Error and Least Significant Change for Two Commonly Used Bioelectrical Impedance Analysis Devices

Bioelectrical impedance analysis (BIA) devices administer electrical currents through surface electrodes to estimate overall body fluids from the measured resistance and reactance of bodily tissues. The proportion of fat versus fat-free mass can be further estimated by these devices using algorithms developed from reference data. BIA devices are commonly used in field as well as laboratory settings due to their convenience, ease of use, and relatively low cost. PURPOSE: The purpose of this study was to determine the day-to-day precision error (PE) and least significant change (LSC) of the percent body fat (PBF), fat mass (FM), and fat-free mass (FFM) estimated by two commonly used BIA devices, the InBody 770 and the Omron HBF-306. METHODS: Seventeen healthy participants (7 males, 10 females) were included in this analysis. Participants visited the laboratory on two separate occasions no more than 48 hours apart and abstained from all food, fluid, caffeine, and alcohol for at least 8 hours prior to each visit. Height and weight were measured using a Seca 769 stadiometer and digital scale. PE was calculated as , where SD is the within-subject standard deviation. LSC was calculated as 2.77 * PE to reflect a 95% confidence level. RESULTS: Participants had a mean ±SD age of 27.1 ±8.3 years, height of 171.6 ±8.5 cm, and weight of 68.0 ±10.6 kg. PE for the InBody was 1.0%, 0.7 kg, and 0.9 kg for PBF, FM, and FFM, respectively; PE for the Omron was 0.6%, 0.4 kg, and 0.6 kg for the same variables. The LSC values of each variable for the InBody were 2.8%, 1.9 kg, and 2.4 kg for PBF, FM, and FFM, respectively; the LSC values for these variables were 1.5%, 1.0 kg, and 1.6 kg for the Omron device. CONCLUSION: Individuals looking to use BIA as a method of detecting true changes in body composition over time should be aware that day-to-day measurement error between estimates were as as high as 1.0% for body fat, 0.7 kg for fat mass, and 0.9 kg for fat-free mass in the current study; therefore, changes within these parameters likely reflect error of measurement and not true physiological differences. Additionally, changes over time between estimates from an InBody 770 device should meet or exceed a difference of at least 2.8% body fat, 1.9 kg FM, or 2.4 kg FFM to increase confidence that the differences are a reflection of physiological changes rather than between-day measurement error; differences between readings from an Omron should meet or exceed 1.5% body fat, 1.0 kg FM, or 1.6 kg FFM for this purpose. The InBody 770 demonstrated higher precision error and thus may entail a higher least significant change to meaningfully detect true physiological changes between time points. However, the observed differences in these values between the InBody 770 and Omron HBF-306 may also indicate that the InBody 770 is more sensitive to small but real changes in bioelectrical impedance values between days. Longitudinal studies are needed to elucidate the comparative tracking validity of these commonly used BIA devices in healthy populations