MUSCULAR STRENGTH AS A PREDICTOR OF BONE MINERAL DENSITY IN COLLEGIATE FEMALE ATHLETES

Emily V. Witte1, Henry N. Williford2, FACSM, Michael R. Esco3, FACSM & Matthew D. Leatherwood2. 1Emporia State University, Emporia, KS; 2Auburn University at Montgomery, Montgomery, AL; 3University of Alabama, Tuscaloosa, AL; e-mail: [email protected] It has been well established that the frequency and duration of impact loading, age, body weight, and body composition are independently correlated with bone mineral density (BMD) in female athletes. However, very little is known about the relationship of strength, in addition to other anthropometric measures, and BMD. PURPOSE: The purpose of this study was to examine the relationship between muscular strength, muscular endurance, sport specific impact loading, age, body composition and body weight simultaneously in regards to BMD in collegiate female athletes. METHODS: Participants included apparently healthy collegiate female athletes from a variety of sports; tennis (n=7), basketball (n=8), soccer (n=7), cross country (n=2), cheer (n=2), and volleyball (n=4). Each subject reported twice during a seven day span to complete the assessments. During the first session, descriptive statistics such as height, weight, BMD and body composition were recorded. Additionally, objective assessments for muscular strength (hand-grip strength, one-repetition max bench press and squat strength), muscular endurance (push-ups and curl-ups) were performed. The second session included the evaluation of maximal oxygen consumption, obtained from a graded exercise test and open circuit spirometry. RESULTS: Using a Pearson correlation, bench press strength displayed the greatest relationship with BMD (r = 0.826). Significant relationships also existed between BMD and fat-free mass (r = 0.739), maximal squat strength (r = 0.666) and hand-grip strength (r = 0.597). A stepwise regression model revealed maximal bench press strength as the most significant variable for predicting total BMD in respect to the variables being measured. In addition, a negative relationship was displayed between BMD and partial curl-ups (r = -0.387) and maximal oxygen uptake (r = -0.360). CONCLUSIONS: These results indicate that the relationship between BMD and muscular strength, particularly maximal bench press strength, may be greater than previously indicated

ABSOLUTE PEAK OXYGEN CONSUMPTION IS INDEPENDENTLY CORRELATED WITH FAT-FREE MASS IN YOUTH SOCCER PLAYERS

Casey J. Metoyer, Oleg Sinelnikov, Michael V. Fedewa, Michael R. Esco, FACSM. The University of Alabama, Tuscaloosa, AL. BACKGROUND: It has been suggested that the relationship between body mass (BM) and peak oxygen consumption (VO2peak) is explained by fat-free mass (FFM) and not fat mass (FM). However, most of the research has occurred in children and adults with obesity, and hence, little is known about these relationships in youth athletes. Therefore, the purpose of the study was to determine the extent of variation in absolute VO2peak that can be independently explained by BM, FM, and FFM in youth soccer players. METHODS: A sample of 20 young male soccer players (age = 13.7 ± 0.8 years, height = 167.0 ± 7.9 cm, weight = 56.2 ± 8.4 kg) participated in this study. Absolute VO2peak was determined from a maximal graded exercise test on a treadmill. Dual-energy x-ray absorptiometry was used to measure FM and FFM. Pearson correlation procedures were used to determine the relationships between absolute VO2peak and the body composition metrics. Stepwise regression was used to determine which body composition metric (BM, FM, or FFM) explained the greatest variation in absolute VO2peak. RESULTS: The average absolute VO2peak, FM, and FFM was 3.1 ± 0.6 L/min, 11.1 ± 2.9 kg, and 46.0 ± 6.9 kg, respectively. Significant correlations were found between VO2peak and BM (r = 0.88, p \u3c 0.001), FM (r = 0.46, p = 0.02), and FFM (r = 0.90, p \u3c 0.001). Stepwise regression showed that only FFM significantly explained the variance in absolute VO2peak (R2 = 0.81, p \u3c 0.001). CONCLUSIONS: The results of this study suggest that FFM explains the relationship between BM and absolute VO2peak in youth soccer players. FM does not display an independent relationship with VO2peak. Therefore, fatness and absolute VO2peak appear to be independent qualities in male youth soccer players. Further research is needed to verify these findings and clarify the relationship between body composition and oxygen consumption in youth athletes

THE TEST-RETEST RELIABILITY OF BODY COMPOSITION MEASURED USING DIGITAL IMAGES FROM A SMARTPHONE APPLICATION

Madeline L. Schwing, Casey J. Metoyer, Katherine Sullivan, Mary E. Lovelady, Michael R. Esco, FACSM, Michael V. Fedewa, FACSM. University of Alabama, Tuscaloosa, AL, AL. BACKGROUND: The ability to measure and track changes in muscle and fat is important for practitioners in the Allied Health and Sports Performance fields. An automated image analysis program was recently developed to measure muscle and fat from a single digital image using a smartphone application. However, the reliability of the application has yet to be assessed. PURPOSE: The purpose of this study was to evaluate the test-retest reliability of %Fat estimates from a single digital image when measured on two consecutive days. METHODS: A convenience sample of participants were included in the study (n=12, 83.33% female, 83.33% Caucasian 31.25±10.49 yrs, 24.82 kg/m2). Data collection occurred on two consecutive days with no more than 36 hours between visits. On Day 1, age, gender, and race were assessed via self-report. A full-body image from the posterior view was taken using an iPad Air 2 (Apple Inc., Cupertino, CA) against a white photography backdrop. A light meter (MT-912, Shenzhen Flus Technology Co., Ltd., Shenzhen, China) was used to measure brightness in Lux and ensure that testing conditions were consistent across both days. Participants returned on Day 2 and performed a second %Fat measurement under similar lighting and backdrop conditions. Images were analyzed using an automated smartphone application (made Health and Fitness LLC, Birmingham, AL. version 1.1.3), which provided estimates of %Fat using a proprietary algorithm. A paired samples t-test was used to assess potential mean differences in %Fat across the two trials. The test-retest reliability across the trials was measured using Pearson’s r, and described as weak, moderate, strong, or near-perfect (r=0.2, 0.5, 0.8, or 0.9, respectively). Data are presented as mean± standard deviation, with statistical significance set at p\u3c0.05. RESULTS: No significant mean differences were observed between measurements obtained on Day 1 (27.16±5.08 %Fat) and Day 2 (27.04±5.49 %Fat) (p=0.65). In addition, a near-perfect correlation was observed between the trials (r=0.99, p\u3c0.001). CONCLUSION: Given the negligible difference between measures and the near-perfect correlation, an inexpensive and portable technique to measure %Fat in field settings may be a valuable alternative when traditional assessment techniques are not available. Future research should examine the reliability across multiple camera types, image resolutions, lighting conditions, and color backgrounds

ESTIMATION OF TOTAL BODY WATER USING SINGLE FREQUENCY BIOIMPEDANCE ANALYSIS: A SYSTEMATIC REVIEW AND META-ANALYSIS

Zackary S. Cicone1, Michael V. Fedewa2, Clifton J. Holmes3, Michael R. Esco, FACSM2, Hayley V. MacDonald2. 1Shenandoah University, Winchester, VA. 2The University of Alabama, Tuscaloosa, AL. 3Washington University in St. Louis, St. Louis, MO. BACKGROUND: Single frequency bioimpedance analysis (SFBIA) is a simple alternative to isotope dilution techniques for assessing total body water (TBW). How characteristics related to the sample (e.g., age, health status) and SFBIA methodology (e.g., criterion technique, device, frequency, index) influence SFBIA accuracy has yet to be comprehensively examined. The aims of this systematic review and meta-analysis were to 1) quantify the accuracy of SFBIA for predicting TBW and 2) determine the potential impact of study-level effect modifiers. METHODS: Five electronic databases were searched for studies that compared isotope dilution TBW values to SFBIA. Standardized mean difference (SMD) effect sizes were calculated using the Gibbons method for each comparison and an overall estimate was generated using a three-level random-effects model. Within- and between-study level variance was evaluated using one-sided log-likelihood-ratio tests. When appropriate, subgroup analyses were performed to identify potential study-level moderators. RESULTS: Aggregate-level data from 51 studies (255 individual effects) were included in the final analysis. Study samples included predominantly healthy participants with large ranges in mean age (0 to 82 y) and body mass index (14.1 to 50.2 kg/m2). The overall SMD indicated a negligible difference between SFBIA and criterion dilution methods (SMD=-0.04, p=0.67), but lacked homogeneity at both the within- (σ2=0.45) and between-study (σ2=0.26) levels (all p\u3c0.001). Moderator analysis revealed that the interaction between frequency and index (p\u3c0.01) influenced the observed error between SFBIA and criterion methods. Resistance index (Ht2/R) produced less error than impedance index (Ht2/Z) across all frequencies (all p\u3e0.10), with Ht2/R at 50 kHz producing the most accurate estimate of TBW (β=0.06, p\u3e0.05). Additionally, there was a small yet significant effect for sample sex (% women, β=-0.003, p\u3c0.05), suggesting that SFBIA may underestimate TBW in samples that are predominantly women. No main effects were observed for other study-level factors (e.g., sample characteristics or BIA methodology). CONCLUSION: Overall, Ht2/R produced less error in TBW estimation than Ht2/Z, with Ht2/R at 50 kHz providing the smallest mean difference in TBW when compared to isotope dilution. These results suggest that SFBIA may provide acceptable estimates of TBW across a range of diverse samples

RELIABILITY OF BODY COMPOSITION MEASURED USING A SMARTPHONE APPLICATION AND DIFFERENT CAMERA RESOLUTIONS

Mary E. Lovelady, Casey J. Metoyer, Katherine Sullivan, Jacob Broeckel, Michael R. Esco, FACSM, Michael V. Fedewa. University Of Alabama, Tuscaloosa, AL. BACKGROUND: Many traditional laboratory methods of measuring body fat percentage (%Fat) are inaccessible to healthcare professionals due to the cost, complexity, time, and portability. Recently, a new smartphone application was developed that allows for an accurate estimate of %Fat by analyzing a single 2-dimensional digital image. Although the validity of the application has been previously examined, the reliability across different camera resolutions has not been thoroughly tested. PURPOSE: The aim of this study was to evaluate the reliability of %Fat estimates from digital images captured using devices with different megapixel cameras. METHODS: A convenience sample of adult participants was recruited for the study (n=12, 83.33% female, 83.33% Caucasian, 31.25±10.49 yrs., 69.44±11.77 kg/m2). Age, gender, and race/ethnicity were assessed via self-report. Height was measured to the nearest 0.1 cm using a stadiometer (SECA 213, Seca Ltd., Hamburg, Germany). Weight was measured to the nearest 0.1 kg using a calibrated digital scale (Tanita BWB-800, Tanita Corporation, Tokyo, Japan). A full-body digital image was taken from the posterior view, with participants standing in front of a white background, using a 12-megapixel iPhone 12 (Apple Inc., Cupertino, CA) (%Fat12mp) and an 8-megapixel iPad Air 2 (Apple Inc., Cupertino, CA) (%Fat8mp). %Fat was derived using an automated smartphone application and a proprietary algorithm (made Health and Fitness, LLC, Birmingham, AL). A paired samples t-test was used to examine potential mean differences between %Fat12mp and %Fat8mp. The reliability was also measured using Pearson’s r, and described as weak, moderate, strong, or near-perfect (r=0.2, 0.5, 0.8, or 0.9 respectively). Data are presented as mean±standard deviation, with an alpha level set to p\u3c0.05. RESULTS: No significant mean differences in %Fat were observed between %Fat12mp and %Fat8mp (26.92±4.96 %Fat and 27.16±3.08 %Fat, respectively; p=0.37). Near-perfect correlations were observed between %Fat12mp and %Fat8mp (r=0.99, p\u3c0.001). DISCUSSION: Based on the results of this study, the smartphone application provides a reliable estimate of %Fat across devices with different megapixel cameras. Future studies should explore other conditions, including different lighting, different color backgrounds, and other devices, as well as within a larger more diverse sample

ASSOCIATION BETWEEN HEALTH-RELATED COMPONENTS AND BODY DISSATISFACTION IN WOMEN

Katherine Sullivan, Jacob Broeckel, Casey J. Metoyer, Andrew D. Fields, Madelyn K. Simmang, Michael R. Esco, FACSM, Michael V. Fedewa. University of Alabama, Tuscaloosa, AL. BACKGROUND: Body dissatisfaction refers to a negative perception or evaluation of one’s body or physical appearance. Higher body dissatisfaction negatively impacts self-esteem, perceived quality of life, and can increase the risk of disordered eating, substance abuse, anxiety, and depression. PURPOSE: To examine the association between body dissatisfaction and health-related components among women. METHODS: A convenience sample of 29 female adults were included in our analysis (90% Caucasian, 24.8±9.2 yrs., 24.9±3.6 kg/m2). Body mass and height were measured and used to calculate body mass index (BMI). Body dissatisfaction scores (BDS) were calculated using the body dissatisfaction subscale of the eating disorder inventory II (EDI-BD). Where applicable, EDI-BD items were reverse scored such that, higher BDS scores indicate greater body dissatisfaction. Health-related components included waist and hip circumference (cm), number of push-ups completed until exhaustion, average dominant and non-dominant hand-grip strength (kg), participant’s perceived functional ability to walk, jog, or run a one-mile and three-mile distance, BMI (kg/m2), physical activity (MET-minutes/week) derived from the short form International Physical Activity Questionnaire, and relative adiposity (%Fat) derived from Dual X-ray Absorptiometry. Bivariate correlations were used to examine the direction and strength of the association between BDS and health-related components. The strength of each r value was considered weak (r=0.2), moderate (r=0.5), or strong (r=0.8). Data are presented as mean±standard deviation, with p\u3c0.05 used to determine statistical significance. RESULTS: No statistically significant correlations (p\u3e.05 for all) were observed between BDS and waist or hip circumference (r=.144, r=.282, respectively), push-ups (r=-.215), dominant or non-dominant hand-grip strength (r=-.121, r=-.086, respectively), perceived ability to complete one-mile or three-miles (r=-.289, r=-.258), BMI (r=.240), or physical activity (r=.094). Significant, moderate correlations were observed between BDS and %Fat (r=.426, p=.021). CONCLUSIONS: Our results indicate a moderate, linear relationship between %Fat and body dissatisfaction. Given the relatively homogenous age, race, and BMI characteristics of the current study, the association between body dissatisfaction and health-related components should be further examined within a larger and more diverse sample

RELIABILITY OF LIGHTING CONDITIONS FOR MEASURING BODY FAT PERCENTAGE VIA IMAGE CAPTURE

Madelyn K. Simmang, Katherine Sullivan, Casey J. Metoyer, Jacob Broeckel, Andrew D. Fields, Mary Lovelady, Maddy Schwing, Michael V. Fedewa, Michael R. Esco, FACSM. University of Alabama, Tuscaloosa, AL. BACKGROUND: A smartphone application has been previously validated to estimate metrics of body composition (%Fat) from a full-body digital image. However, the reliability of the automated image analysis program has not been extensively examined under varying lighting conditions. PURPOSE: The aim of this study was to evaluate the reliability of %Fat estimates measured under Low(LL) Ambient(AL), Moderate(ML), and Bright-Light(BL) conditions. METHODS: A convenience sample of participants were included in the study (n=12, 83.3% female, 83.3% Caucasian, 31.25±10.49 yrs, 24.82±2.85 kg/m2). Age, gender, and race were assessed via self-report. Full-body digital images were taken in front of a white photography backdrop under LL, AL, ML, and BL lighting conditions (\u3c50 Lux, 300-400 Lux, 600-800 Lux, and \u3e900 Lux, respectively). Images were taken from the posterior view and were captured using an iPad Air 2 (Apple Inc., Cupertino, CA). A light meter (MT-912, Shenzhen Flus Technology Co., Ltd., Shenzhen China) was used to measure the level of illuminance in Lux. Images were analyzed using an automated smartphone application (made Health and Fitness LLC, Birmingham AL. version 1.1.3), which provided estimates of %Fat using a proprietary algorithm. A repeated measures ANOVA was used to assess potential mean differences in %Fat across the four lighting conditions, with the reliability assessed using a 2-way ICC with absolute agreement. The strength of the ICC value was considered weak, moderate, strong, or near-perfect (r=0.2, 0.5, 0.8, and 0.9 respectively). Data are presented as mean±standard deviation, with statistical significance set at p\u3c.05. RESULTS: Significant differences were observed across conditions (p=.047), such that %FatLL (27.62±4.95 %Fat) was slightly higher than the %FatBL (26.94±5.44 %Fat) (p=.018), but not different than the %FatAL (27.16±5.08 %Fat) or %FatML (27.31±5.23 %Fat) conditions (both p\u3e.05). No other differences were observed between conditions (all p\u3e.05). Near-perfect agreement between %FatLL and the %FatAL, %FatML, and %FatBL conditions (ICC=0.984, 0.985 0.991, respectively; all p\u3c.001) was observed. CONCLUSION: Based on the results of the study, a small difference was observed between %Fat estimates obtained under LL and BL conditions. However, the agreement between all conditions was near-perfect. These results suggest that %Fat can be estimated from a single digital image using a smartphone application across various lighting conditions with acceptable reliability

RELATIONSHIPS OF BODY COMPOSITION FACTORS WITH COMPONENTS OF PHYSICAL ACTIVITY AND MUSCULAR FITNESS

Andrew D. Fields, Katherine Sullivan, Casey Metoyer, Jacob Broeckel, Madelyn K. Simmang, Mary Lovelady, Maddy Schwing, Michael V. Fedewa, Michael R. Esco, FACSM. University of Alabama, Tuscaloosa, AL. BACKGROUND: It is commonly accepted that body composition is related to physical activity (PA) and muscular fitness (MF). However, it is not as well understood if metrics of PA and MF can explain the variance in both fat mass (FM) and fat-free mass (FFM). PURPOSE: The purpose of this investigation was to determine the extent of variation in FM and FFM that can be explained by specific components of PA and MF. METHODS: A convenience sample of participants was recruited for this study (n=37, 27.03% Female, 22.35±3.76 yrs.). All metrics were assessed during a single visit to the Exercise Physiology Lab. Body mass (BM) was measured to the nearest 0.1 kg with a calibrated digital scale (Tanita BWB-800, Tanita Corporation, Tokyo, Japan). Results from the International Physical Activity Questionnaire (IPAQ) Short-Form were converted to calculate the intensity and amount of weekly PA in MET-minutes per week (MET-min/wk). Intensities were categorized into vigorous, moderate, and walking based on IPAQ standards. FM was estimated using brightness-mode ultrasound (Philips iU22, Philips Medical Systems, Andover, MA, USA) across seven standardized sites. FFM was derived from subtracting FM from BM. Handgrip strength (HGS) was assessed on dominant hand via a hydraulic hand dynamometer (Alphamed Inc., Lakewood, NJ, USA) as a metric of muscular strength, and a maximum-rep push-up test was administered to quantify muscular endurance. The correlations between PA, MF, FM, and FFM were assessed using Pearson’s r, and described as weak, moderate, or strong (r=0.2, 0.5, or 0.8, respectively). Data are presented as mean±standard deviation, with an alpha level set to p\u3c0.05. RESULTS: There were no significant correlations found between FM and any of the PA or MF measures, (r=-0.28 to 0.24, all p\u3e0.05). FFM was moderately correlated with vigorous MET-min/wk (r=0.34, p=0.04) and walking MET-min/wk, (r=-0.37, p=0.02), and strongly correlated with and HGS (r=0.80, p\u3c0.001). Stepwise regression analysis showed that only HGS and vigorous MET-min/wk were included in the model that explained the variance in FFM (R2=0.74, p\u3c0.001). DISCUSSION: The results indicate that muscular strength and vigorous PA have stronger relationships with FFM than muscular endurance or other, lower-intensity metrics of PA. FM does not appear to be related to either MF parameters or IPAQ-derived PA